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Neumann S, Kuteykin-Teplyakov K, Heumann R. Neuronal Protection by Ha-RAS-GTPase Signaling through Selective Downregulation of Plasmalemmal Voltage-Dependent Anion Channel-1. Int J Mol Sci 2024; 25:3030. [PMID: 38474278 DOI: 10.3390/ijms25053030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/14/2024] Open
Abstract
The small GTPase RAS acts as a plasma membrane-anchored intracellular neurotrophin counteracting neuronal degeneration in the brain, but the underlying molecular mechanisms are largely unknown. In transgenic mice expressing constitutively activated V12-Ha-RAS selectively in neurons, proteome analysis uncovered a 70% decrease in voltage-dependent anion channel-1 (VDAC-1) in the cortex and hippocampus. We observed a corresponding reduction in the levels of mRNA splicing variant coding for plasma membrane-targeted VDAC-1 (pl-VDAC-1) while mRNA levels for mitochondrial membrane VDAC-1 (mt-VDAC-1) remained constant. In primary cortical neurons derived from V12-Ha-RAS animals, a decrease in pl-VDAC-1 mRNA levels was observed, accompanied by a concomitant reduction in the ferricyanide reductase activity associated with VDAC-1 protein. Application of MEK inhibitor U0126 to transgenic cortical neurons reconstituted pl-VDAC-1 mRNA to reach wild-type levels. Excitotoxic glutamate-induced cell death was strongly attenuated in transgenic V12-Ha-RAS overexpressing cortical cultures. Consistently, a neuroprotective effect could also be achieved in wild-type cortical cultures by the extracellular application of channel-blocking antibody targeting the N-terminus of VDAC-1. These results may encourage novel therapeutic approaches toward blocking pl-VDAC-1 by monoclonal antibody targeting for complementary treatments in transplantation and neurodegenerative disease.
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Affiliation(s)
- Sebastian Neumann
- Department of Biochemistry II-Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Konstantin Kuteykin-Teplyakov
- Department of Biochemistry II-Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801 Bochum, Germany
| | - Rolf Heumann
- Department of Biochemistry II-Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801 Bochum, Germany
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2
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Roy R, Chatterjee N, Khan MS, Sultana F, Roy A, Naskar S, Guha R, Sen S, Chakrabarti J, Chatterjee BP, Panda CK, Dutta S. High prevalence of CD44 and its ligand low molecular weight hyaluronan in plasma of HNSCC patients: clinical significance. Mol Biol Rep 2024; 51:157. [PMID: 38252332 DOI: 10.1007/s11033-023-08950-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 11/08/2023] [Indexed: 01/23/2024]
Abstract
BACKGROUND This study aims to evaluate the role of cancer stem cell marker, CD44, and its ligand HA as potential molecular biomarker for early detection of HNSCC. METHODS AND RESULTS The expression profile (mRNA/Protein) of CD44 variants were analysed in primary HNSCC lesions and plasma of the patients. Then, prevalence of HA variants was analysed in plasma of the patients. The mRNA expression of CD44 variants, CD44S and CD44v3, were significantly high in both early (stage I/II) and late (stage III/IV) invasive lesions, with predominant expression of CD44v3 in the late-stage lesions. In plasma of HNSCC patients, increased levels of SolCD44, CD44-ICD and unique 62 KD CD44 variants with respect to standard CD44S were seen, in comparison to their prevalence in plasma of normal individuals. The abundance of CD44-ICD and 62 KD variants were significantly high in plasma of late stage HNSCC patients. Interestingly, significantly high level of low molecular weight HA(LMW HA) with respect to high molecular weight HA(HMW HA) was seen in plasma of HNSCC patients irrespective of clinical stages. On the contrary, high HMW HA level in plasma of normal individuals was seen. The high level of LMW HA in plasma of HNSCC patients might be due to combinatorial effect of increased mRNA expression of HA synthesizing enzyme HAS1/2/3 and HA degrading enzyme HYAL1/2, as seen in the primary HNSCC samples. CONCLUSION Thus, our data revealed the importance of specific CD44 and HA variants in plasma of HNSCC patients during its development as potential non-invasive molecular biomarker of the disease.
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Affiliation(s)
- Rituparna Roy
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Nilanjana Chatterjee
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Md Sadi Khan
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Farhin Sultana
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Arindam Roy
- Department of Surgical Oncology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Sukanya Naskar
- Department of Head and Neck Surgical Oncology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Rajdeep Guha
- Department of Head and Neck Surgical Oncology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Sagar Sen
- Department of Surgical Oncology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Jayanta Chakrabarti
- Department of Surgical Oncology, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Bishnu Pada Chatterjee
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India
| | - Chinmay Kumar Panda
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India.
| | - Sankhadeep Dutta
- Department of Oncogene Regulation, Chittaranjan National Cancer Institute, Kolkata, West Bengal, India.
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3
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Goto N, Suzuki H, Zheng L, Okano Y, Okita Y, Watanabe Y, Kato Y, Kato M. Promotion of squamous cell carcinoma tumorigenesis by oncogene-mediated THG-1/TSC22D4 phosphorylation. Cancer Sci 2023; 114:3972-3983. [PMID: 37607779 PMCID: PMC10551599 DOI: 10.1111/cas.15934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/24/2023] Open
Abstract
Carcinoma cells possess high proliferative and invasive potentials and exhibit a resilience against stresses, metabolic disorder, and therapeutic efforts. These properties are mainly acquired by genetic alterations including driver gene mutations. However, the detailed molecular mechanisms have not been fully elucidated. Here, we provide a novel mechanism connecting oncogenic signaling and the tumorigenic properties by a transforming growth factor-β1-stimulated clone 22 (TSC-22) family protein, THG-1 (also called as TSC22D4). THG-1 is localized at the basal layer of normal squamous epithelium and overexpressed in squamous cell carcinomas (SCCs). THG-1 knockdown suppressed SCC cell proliferation, invasiveness, and xenograft tumor formation. In contrast, THG-1 overexpression promoted the EGF-induced proliferation and stratified epithelium formation. Furthermore, THG-1 is phosphorylated by the receptor tyrosine kinase (RTK)-RAS-ERK pathway, which promoted the oncogene-mediated tumorigenesis. Moreover, THG-1 involves in the alternative splicing of CD44 variants, a regulator of invasiveness, stemness, and oxidative stress resistance under the RTK pathway. These findings highlight the pivotal roles of THG-1 as a novel effector of SCC tumorigenesis, and the detection of THG-1 phosphorylation by our established specific antibody could contribute to cancer diagnosis and therapy.
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Affiliation(s)
- Nohara Goto
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
- Ph.D. Program in Human Biology, School of Integrative and Global MajorsUniversity of TsukubaTsukubaJapan
| | - Hiroyuki Suzuki
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
- Department of Antibody Drug DevelopmentTohoku University Graduate School of MedicineSendaiJapan
| | - Ling Zheng
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yasuhito Okano
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yukari Okita
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yukihide Watanabe
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
| | - Yukinari Kato
- Department of Antibody Drug DevelopmentTohoku University Graduate School of MedicineSendaiJapan
| | - Mitsuyasu Kato
- Department of Experimental Pathology, Faculty of MedicineUniversity of TsukubaTsukubaJapan
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4
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Suzuki H, Ozawa K, Tanaka T, Kaneko MK, Kato Y. Development of a Novel Anti-CD44 Variant 7/8 Monoclonal Antibody, C44Mab-34, for Multiple Applications against Oral Carcinomas. Biomedicines 2023; 11:biomedicines11041099. [PMID: 37189717 DOI: 10.3390/biomedicines11041099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/29/2023] [Accepted: 04/03/2023] [Indexed: 04/08/2023] Open
Abstract
Cluster of differentiation 44 (CD44) has been investigated as a cancer stem cell (CSC) marker as it plays critical roles in tumor malignant progression. The splicing variants are overexpressed in many carcinomas, especially squamous cell carcinomas, and play critical roles in the promotion of tumor metastasis, the acquisition of CSC properties, and resistance to treatments. Therefore, each CD44 variant (CD44v) function and distribution in carcinomas should be clarified for the establishment of novel tumor diagnosis and therapy. In this study, we immunized mouse with a CD44 variant (CD44v3–10) ectodomain and established various anti-CD44 monoclonal antibodies (mAbs). One of the established clones (C44Mab-34; IgG1, kappa) recognized a peptide that covers both variant 7- and variant 8-encoded regions, indicating that C44Mab-34 is a specific mAb for CD44v7/8. Moreover, C44Mab-34 reacted with CD44v3–10-overexpressed Chinese hamster ovary-K1 (CHO) cells or the oral squamous cell carcinoma (OSCC) cell line (HSC-3) by flow cytometry. The apparent KD of C44Mab-34 for CHO/CD44v3–10 and HSC-3 was 1.4 × 10−9 and 3.2 × 10−9 M, respectively. C44Mab-34 could detect CD44v3–10 in Western blotting and stained the formalin-fixed paraffin-embedded OSCC in immunohistochemistry. These results indicate that C44Mab-34 is useful for detecting CD44v7/8 in various applications and is expected to be useful in the application of OSCC diagnosis and therapy.
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Affiliation(s)
- Hiroyuki Suzuki
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
| | - Kazuki Ozawa
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
| | - Tomohiro Tanaka
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
| | - Mika K. Kaneko
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
| | - Yukinari Kato
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Miyagi, Japan
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5
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Zhu H, Zhou W, Wan Y, Lu J, Ge K, Jia C. CD44V3, an Alternatively Spliced Form of CD44, Promotes Pancreatic Cancer Progression. Int J Mol Sci 2022; 23:ijms232012061. [PMID: 36292918 PMCID: PMC9603666 DOI: 10.3390/ijms232012061] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 09/25/2022] [Accepted: 10/02/2022] [Indexed: 12/24/2022] Open
Abstract
Pancreatic cancer is one of the most lethal malignant tumors. However, the molecular mechanisms responsible for its progression are little known. This study aimed to understand the regulatory role of CD44V3 in pancreatic cancer. A Kaplan–Meier analysis was performed to reveal the correlation between CD44/CD44V3 expression and the prognosis of pancreatic cancer patients. CD44V3 and U2AF1 were knocked down using shRNAs. The proliferation, migration, invasion, and stemness of two pancreatic cell lines, BxPC-3 and AsPC-1, were examined. The expression of CD44V3, cancer-associated markers, and the activation of AKT signaling were detected by qRT-PCR and Western blot. Both CD44 and CD44V3 expression levels were associated with a poor prognosis in pancreatic cancer patients. Interestingly, the expression of CD44V3, instead of CD44, was greatly increased in tumor tissues. CD44V3 knockdown inhibited the proliferation, migration, invasion, and stemness of cancer cells. CD44V3 splicing was regulated by U2AF1 and downregulation of U2AF1 enhanced CD44V3 expression, which promoted pancreatic cancer progression. CD44V3 is an important cancer-promoting factor, which may serve as a potential candidate for pancreatic cancer intervention.
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6
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Grande V, Hathazi D, O'Connor E, Marteau T, Schara-Schmidt U, Hentschel A, Gourdon G, Nikolenko N, Lochmüller H, Roos A. Dysregulation of GSK3β-Target Proteins in Skin Fibroblasts of Myotonic Dystrophy Type 1 (DM1) Patients. J Neuromuscul Dis 2021; 8:603-619. [PMID: 33682722 DOI: 10.3233/jnd-200558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is the most common monogenetic muscular disorder of adulthood. This multisystemic disease is caused by CTG repeat expansion in the 3'-untranslated region of the DM1 protein kinase gene called DMPK. DMPK encodes a myosin kinase expressed in skeletal muscle cells and other cellular populations such as smooth muscle cells, neurons and fibroblasts. The resultant expanded (CUG)n RNA transcripts sequester RNA binding factors leading to ubiquitous and persistent splicing deregulation. The accumulation of mutant CUG repeats is linked to increased activity of glycogen synthase kinase 3 beta (GSK3β), a highly conserved and ubiquitous serine/threonine kinase with functions in pathways regulating inflammation, metabolism, oncogenesis, neurogenesis and myogenesis. As GSK3β-inhibition ameliorates defects in myogenesis, muscle strength and myotonia in a DM1 mouse model, this kinase represents a key player of DM1 pathobiochemistry and constitutes a promising therapeutic target. To better characterise DM1 patients, and monitor treatment responses, we aimed to define a set of robust disease and severity markers linked to GSK3βby unbiased proteomic profiling utilizing fibroblasts derived from DM1 patients with low (80- 150) and high (2600- 3600) CTG-repeats. Apart from GSK3β increase, we identified dysregulation of nine proteins (CAPN1, CTNNB1, CTPS1, DNMT1, HDAC2, HNRNPH3, MAP2K2, NR3C1, VDAC2) modulated by GSK3β. In silico-based expression studies confirmed expression in neuronal and skeletal muscle cells and revealed a relatively elevated abundance in fibroblasts. The potential impact of each marker in the myopathology of DM1 is discussed based on respective function to inform potential uses as severity markers or for monitoring GSK3β inhibitor treatment responses.
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Affiliation(s)
- Valentina Grande
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Denisa Hathazi
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Emily O'Connor
- Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Theo Marteau
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Ulrike Schara-Schmidt
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Andreas Hentschel
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany
| | - Genevieve Gourdon
- Centre de Recherche en Myologie, Association Institut de Myologie, Sorbonne Université, Inserm UMR 974, Paris, France
| | - Nikoletta Nikolenko
- National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, UK
| | - Hanns Lochmüller
- Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Centro Nacional de AnálisisGenómico, Center for Genomic Regulation (CNAG-CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Andreas Roos
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany.,Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
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7
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Fibronectin in development and wound healing. Adv Drug Deliv Rev 2021; 170:353-368. [PMID: 32961203 DOI: 10.1016/j.addr.2020.09.005] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 08/26/2020] [Accepted: 09/15/2020] [Indexed: 01/15/2023]
Abstract
Fibronectin structure and composition regulate contextual cell signaling. Recent advances have been made in understanding fibronectin and its role in tissue organization and repair. This review outlines fibronectin splice variants and their functions, evaluates potential therapeutic strategies targeting or utilizing fibronectin, and concludes by discussing potential future directions to modulate fibronectin function in development and wound healing.
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8
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Zhang Y, Qian J, Gu C, Yang Y. Alternative splicing and cancer: a systematic review. Signal Transduct Target Ther 2021; 6:78. [PMID: 33623018 PMCID: PMC7902610 DOI: 10.1038/s41392-021-00486-7] [Citation(s) in RCA: 168] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 09/24/2020] [Accepted: 09/28/2020] [Indexed: 01/31/2023] Open
Abstract
The abnormal regulation of alternative splicing is usually accompanied by the occurrence and development of tumors, which would produce multiple different isoforms and diversify protein expression. The aim of the present study was to conduct a systematic review in order to describe the regulatory mechanisms of alternative splicing, as well as its functions in tumor cells, from proliferation and apoptosis to invasion and metastasis, and from angiogenesis to metabolism. The abnormal splicing events contributed to tumor progression as oncogenic drivers and/or bystander factors. The alterations in splicing factors detected in tumors and other mis-splicing events (i.e., long non-coding and circular RNAs) in tumorigenesis were also included. The findings of recent therapeutic approaches targeting splicing catalysis and splicing regulatory proteins to modulate pathogenically spliced events (including tumor-specific neo-antigens for cancer immunotherapy) were introduced. The emerging RNA-based strategies for the treatment of cancer with abnormally alternative splicing isoforms were also discussed. However, further studies are still required to address the association between alternative splicing and cancer in more detail.
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Affiliation(s)
- Yuanjiao Zhang
- The Third Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jinjun Qian
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Chunyan Gu
- The Third Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China.
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China.
| | - Ye Yang
- The Third Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China.
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China.
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9
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Martín Moyano P, Němec V, Paruch K. Cdc-Like Kinases (CLKs): Biology, Chemical Probes, and Therapeutic Potential. Int J Mol Sci 2020; 21:E7549. [PMID: 33066143 PMCID: PMC7593917 DOI: 10.3390/ijms21207549] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022] Open
Abstract
Protein kinases represent a very pharmacologically attractive class of targets; however, some members of the family still remain rather unexplored. The biology and therapeutic potential of cdc-like kinases (CLKs) have been explored mainly over the last decade and the first CLK inhibitor, compound SM08502, entered clinical trials only recently. This review summarizes the biological roles and therapeutic potential of CLKs and their heretofore published small-molecule inhibitors, with a focus on the compounds' potential to be utilized as quality chemical biology probes.
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Affiliation(s)
- Paula Martín Moyano
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic; (P.M.M.); (V.N.)
| | - Václav Němec
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic; (P.M.M.); (V.N.)
- International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne’s University Hospital in Brno, 602 00 Brno, Czech Republic
| | - Kamil Paruch
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic; (P.M.M.); (V.N.)
- International Clinical Research Center, Center for Biomolecular and Cellular Engineering, St. Anne’s University Hospital in Brno, 602 00 Brno, Czech Republic
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10
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Cherry S, Lynch KW. Alternative splicing and cancer: insights, opportunities, and challenges from an expanding view of the transcriptome. Genes Dev 2020; 34:1005-1016. [PMID: 32747477 PMCID: PMC7397854 DOI: 10.1101/gad.338962.120] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Over the past decade there has been increased awareness of the potential role of alternative splicing in the etiology of cancer. In particular, advances in RNA-Sequencing technology and analysis has led to a wave of discoveries in the last few years regarding the causes and functional relevance of alternative splicing in cancer. Here we discuss the current understanding of the connections between splicing and cancer, with a focus on the most recent findings. We also discuss remaining questions and challenges that must be addressed in order to use our knowledge of splicing to guide the diagnosis and treatment of cancer.
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Affiliation(s)
- Sara Cherry
- Department of Pathology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Kristen W Lynch
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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11
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Prolactin-Responsive Circular RNA circHIPK3 Promotes Proliferation of Mammary Epithelial Cells from Dairy Cow. Genes (Basel) 2020; 11:genes11030336. [PMID: 32245109 PMCID: PMC7141114 DOI: 10.3390/genes11030336] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/18/2020] [Accepted: 03/18/2020] [Indexed: 12/15/2022] Open
Abstract
The highly expressed circHIPK3 is a circular RNA that has been previously reported to regulate the growth of human cells. In this study, we found an increased expression of circHIPK3 in bovine mammary epithelial cells treated with prolactin (PRL) in high-throughput sequencing data. Thus, we further investigated the effect of circHIPK3 on the proliferation and differentiation of mammary epithelial cells. We used qRT-PCR/Cell Counting Kit-8 (CCK-8) and a Western blotting analysis to evaluate the effects on cell proliferation. We found that circHIPK3 promotes the proliferation of mammary epithelial cells. The STAT5 signaling pathway was previously associated with the prolactin response and when the STAT5 was suppressed, the expression of circHIPK3 decreased. The results suggest that the response to prolactin and the associated STAT5 signaling pathway affect the expression of circHIPK3, which subsequently affects the proliferation of mammary epithelial cells in dairy cows.
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12
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The Oncogene Metadherin Interacts with the Known Splicing Proteins YTHDC1, Sam68 and T-STAR and Plays a Novel Role in Alternative mRNA Splicing. Cancers (Basel) 2019; 11:cancers11091233. [PMID: 31450747 PMCID: PMC6770463 DOI: 10.3390/cancers11091233] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/13/2019] [Accepted: 08/21/2019] [Indexed: 11/16/2022] Open
Abstract
Oncogenic metadherin is a key contributor to tumourigenesis with metadherin expression and cytoplasmic localisation previously linked to poor survival. A number of reports have shown metadherin localises specifically to nuclear speckles known to be rich in RNA-binding proteins including the splicing proteins YTHDC1, Sam68 and T-STAR, that have been shown to select alternative splice sites in mRNA of tumour-associated proteins including BRCA, MDM2 and VEGF. Here we investigate the interaction and relationship between metadherin and the splice factors YTHDC1, T-STAR and Sam68. Using a yeast two-hybrid assay and immunoprecipitation we show that metadherin interacts with YTHDC1, Sam68 and T-STAR and demonstrate that T-STAR is significantly overexpressed in prostate cancer tissue compared to benign prostate tissue. We also demonstrate that metadherin influences splice site selection in a dose-dependent manner in CD44v5-luc minigene reporter assays. Finally, we demonstrate that prostate cancer patients with higher metadherin expression have greater expression of the CD44v5 exon. CD44v5 expression could be used to discriminate patients with poor outcomes following radical prostatectomy. In this work we show for the first time that metadherin interacts with, and modulates, the function of key components of splicing associated with cancer development and progression.
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13
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Differential Interleukin-2 Transcription Kinetics Render Mouse but Not Human T Cells Vulnerable to Splicing Inhibition Early after Activation. Mol Cell Biol 2019; 39:MCB.00035-19. [PMID: 31160491 DOI: 10.1128/mcb.00035-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 05/28/2019] [Indexed: 12/24/2022] Open
Abstract
T cells are nodal players in the adaptive immune response against pathogens and malignant cells. Alternative splicing plays a crucial role in T cell activation, which is analyzed mainly at later time points upon stimulation. Here we have discovered a 2-h time window early after stimulation where optimal splicing efficiency or, more generally, gene expression efficiency is crucial for successful T cell activation. Reducing the splicing efficiency at 4 to 6 h poststimulation significantly impaired murine T cell activation, which was dependent on the expression dynamics of the Egr1-Nab2-interleukin-2 (IL-2) pathway. This time window overlaps the time of peak IL-2 de novo transcription, which, we suggest, represents a permissive time window in which decreased splicing (or transcription) efficiency reduces mature IL-2 production, thereby hampering murine T cell activation. Notably, the distinct expression kinetics of the Egr1-Nab2-IL-2 pathway between mouse and human render human T cells refractory to this vulnerability. We propose that the rational temporal modulation of splicing or transcription during peak de novo expression of key effectors can be used to fine-tune stimulation-dependent biological outcomes. Our data also show that critical consideration is required when extrapolating mouse data to the human system in basic and translational research.
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KAWAI TAKEO, IWATA KEISUKE, SHINOTSUKA YUNA, KUBO SAYAKA, MASUOKA HIROO, YABUTA TOMONORI, HIROKAWA MITSUYOSHI, NAKAMURA HIROTOSHI, MIYAUCHI AKIRA, KOMAI KOICHIRO. CD44v8-10 and CD44s Are Age-dependently Expressed in Primary Cultured Papillary Thyroid Carcinoma Cells and Are Associated with Cell Proliferation. THE KOBE JOURNAL OF MEDICAL SCIENCES 2019; 65:E1-E9. [PMID: 31341151 PMCID: PMC6668591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 01/07/2019] [Indexed: 06/10/2023]
Abstract
Papillary thyroid carcinoma (PTC) is the most common endocrine malignancy, arising from follicular cells, and accounts for more than 80% of all thyroid malignant tumors. Although age is the strongest prognostic factor of PTC, and various cut-off ages (40-55 years) were suggested in previous studies, the molecular mechanisms causing age-related changes of PTC cell proliferation remain unclear. CD44 is a major cell surface receptor for hyaluronate and is known as a cancer stem cell marker. However, the association between CD44 and PTC is still unknown. Therefore, we determined the proliferation of primary cultured cells obtained from patients with PTC, and the CD44 mRNA expression profile to elucidate age-related association of CD44 with PTC. The results showed that cell proliferation was significantly decreased according to age. We also found that CD44v8-10 and CD44 splice variants were expressed dominantly in patients with PTC. Moreover, the CD44v8-10/CD44s mRNA expression ratio was significantly increased according to age, and there was a significant negative correlation between this expression ratio and cell proliferation. Our findings suggest that the CD44v8-10/CD44s expression ratio in PTC cells is useful for screening for aggressive PTC and may provide clinically valuable information.
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Affiliation(s)
- TAKEO KAWAI
- Division of Medical Biophysics, Department of Biophysics, Graduate School of Health Sciences, Kobe University, Kobe, Japan
- Department of Clinical Laboratory, Kuma Hospital, Kobe, Japan
| | - KEISUKE IWATA
- Division of Medical Biophysics, Department of Biophysics, Graduate School of Health Sciences, Kobe University, Kobe, Japan
| | - YUNA SHINOTSUKA
- Division of Medical Biophysics, Department of Biophysics, Graduate School of Health Sciences, Kobe University, Kobe, Japan
| | - SAYAKA KUBO
- Division of Medical Biophysics, Department of Biophysics, Graduate School of Health Sciences, Kobe University, Kobe, Japan
| | | | | | | | | | | | - KOICHIRO KOMAI
- Division of Medical Biophysics, Department of Biophysics, Graduate School of Health Sciences, Kobe University, Kobe, Japan
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15
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Kashyap T, Pramanik KK, Nath N, Mishra P, Singh AK, Nagini S, Rana A, Mishra R. Crosstalk between Raf-MEK-ERK and PI3K-Akt-GSK3β signaling networks promotes chemoresistance, invasion/migration and stemness via expression of CD44 variants (v4 and v6) in oral cancer. Oral Oncol 2018; 86:234-243. [PMID: 30409306 DOI: 10.1016/j.oraloncology.2018.09.028] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 08/28/2018] [Accepted: 09/28/2018] [Indexed: 12/28/2022]
Abstract
BACKGROUND The cell-surface glycoprotein CD44 is an important oral cancer stem cell (OCSC) marker and plays significant role in oral squamous cell carcinoma (OSCC) aggressiveness, however, the regulation of CD44 is incompletely understood. METHODS In the present study, 145 fresh human OSCC tissue specimens, including 18 adjacent normal, 42 noninvasive (N0), 53 invasive tumor samples (N1-3) and 32 chemo-radiation resistant samples (RCRT), were included. The expression of CD44 standard (CD44s) and variants (CD44v4, CD44v6); the activation of pERK1/2, GSK3β, NICD (Notch) pathways; the cell viability; and the MMP-9/-2 activity were assessed using RT-PCR, immunohistochemistry, Western blotting, MTT assay and gelatin zymography. OSCC cell lines, including parental (SCC9/SCC4) and Cisplatin-resistant (CisR-SCC9/-SCC4) cells, were used. Knock down of CD44v4/CD44v6 (by siRNA) or inactivation of MAPK/PI3K pathways using specific PD98059/LY294002 was achieved for in vitro analysis of chemoresistance and invasion/migration. RESULTS Elevated CD44 variants were associated with overall OSCC progression, chemoresistance and invasion. Positive correlations were observed, mainly between the expression of CD44v4 and the activation of ERK1/2 causing chemoresistance, whereas CD44v6 expression and inactivation of GSK3β caused invasiveness of OSCC. Cisplatin resistant, CisR-SCC9/SCC4 cell lines showed OCSC properties. Inhibition of MEK/ERK1/2 by SMI or knock down (KD) of CD44v4 by siRNA reversed cisplatin-resistance, whereas blocking the PI3K/Akt/GSK3β pathway by SMI or KD of CD44v6 isoforms by respective siRNA diminished invasion/metastasis potential. CONCLUSION Collectively, our results demonstrated that CD44v4 expression is more linked with ERK1/2 activation and promote cisplatin resistance, whereas CD44v6 expression is associated primarily with PI3K/Akt/GSK3β activation and driving tumor invasion/migration.
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Affiliation(s)
- Tanushree Kashyap
- Centre for Life Sciences, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835205, Jharkhand, India
| | - Kamdeo K Pramanik
- Centre for Life Sciences, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835205, Jharkhand, India
| | - Nidhi Nath
- Centre for Life Sciences, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835205, Jharkhand, India
| | - Prajna Mishra
- Centre for Applied Chemistry, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835205, Jharkhand, India
| | - Abhay K Singh
- Centre for Life Sciences, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835205, Jharkhand, India
| | - Siddavaram Nagini
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar 608 002, Tamil Nadu, India
| | - Ajay Rana
- Division of Surgical Oncology, Department of Surgery, College of Medicine, The University of Illinois at Chicago 840 S. Wood Street, Suite 601 Clinical Sciences Building, MC 958, Chicago, IL 60612 USA
| | - Rajakishore Mishra
- Centre for Life Sciences, School of Natural Sciences, Central University of Jharkhand, Ratu-Lohardaga Road, Brambe, Ranchi 835205, Jharkhand, India.
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Schaub A, Glasmacher E. Splicing in immune cells-mechanistic insights and emerging topics. Int Immunol 2018; 29:173-181. [PMID: 28498981 PMCID: PMC5890895 DOI: 10.1093/intimm/dxx026] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 04/27/2017] [Indexed: 11/26/2022] Open
Abstract
Differential splicing of mRNAs not only enables regulation of gene expression levels, but also ensures a high degree of gene-product diversity. The extent to which splicing of mRNAs is utilized as a mechanism in immune cells has become evident within the last few years. Still, only a few of these mechanisms have been well studied. In this review, we discuss some of the best-understood mechanisms, for instance the differential splicing of CD45 in T cells, as well as immunoglobulin genes in B cells. Beyond that we provide general mechanistic insights on how, when and where this process takes place and discuss the current knowledge regarding these topics in immune cells. We also highlight some of the reported links to immune-related diseases, genome-wide sequencing studies that revealed thousands of differentially spliced transcripts, as well as splicing studies on immune cells that remain mechanistically not fully understood. We thereby display potential emerging topics for future studies centered on splicing mechanisms in immune cells.
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Affiliation(s)
- Annalisa Schaub
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
| | - Elke Glasmacher
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Center for Diabetes Research (DZD), 85764 München-Neuherberg, Germany
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17
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Rios de la Rosa JM, Tirella A, Tirelli N. Receptor-Targeted Drug Delivery and the (Many) Problems We Know of: The Case of CD44 and Hyaluronic Acid. ACTA ACUST UNITED AC 2018. [DOI: 10.1002/adbi.201800049] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Julio M. Rios de la Rosa
- NorthWest Centre for Advanced Drug Delivery (NoWCADD); School of Health Sciences; University of Manchester; Oxford Road Manchester M13 9PT UK
| | - Annalisa Tirella
- NorthWest Centre for Advanced Drug Delivery (NoWCADD); School of Health Sciences; University of Manchester; Oxford Road Manchester M13 9PT UK
| | - Nicola Tirelli
- NorthWest Centre for Advanced Drug Delivery (NoWCADD); School of Health Sciences; University of Manchester; Oxford Road Manchester M13 9PT UK
- Laboratory of Polymers and Biomaterials; Fondazione Istituto Italiano di Tecnologia; Genova 16163 Italy
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18
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Nakka K, Ghigna C, Gabellini D, Dilworth FJ. Diversification of the muscle proteome through alternative splicing. Skelet Muscle 2018; 8:8. [PMID: 29510724 PMCID: PMC5840707 DOI: 10.1186/s13395-018-0152-3] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/15/2018] [Indexed: 12/16/2022] Open
Abstract
Background Skeletal muscles express a highly specialized proteome that allows the metabolism of energy sources to mediate myofiber contraction. This muscle-specific proteome is partially derived through the muscle-specific transcription of a subset of genes. Surprisingly, RNA sequencing technologies have also revealed a significant role for muscle-specific alternative splicing in generating protein isoforms that give specialized function to the muscle proteome. Main body In this review, we discuss the current knowledge with respect to the mechanisms that allow pre-mRNA transcripts to undergo muscle-specific alternative splicing while identifying some of the key trans-acting splicing factors essential to the process. The importance of specific splicing events to specialized muscle function is presented along with examples in which dysregulated splicing contributes to myopathies. Though there is now an appreciation that alternative splicing is a major contributor to proteome diversification, the emergence of improved “targeted” proteomic methodologies for detection of specific protein isoforms will soon allow us to better appreciate the extent to which alternative splicing modifies the activity of proteins (and their ability to interact with other proteins) in the skeletal muscle. In addition, we highlight a continued need to better explore the signaling pathways that contribute to the temporal control of trans-acting splicing factor activity to ensure specific protein isoforms are expressed in the proper cellular context. Conclusions An understanding of the signal-dependent and signal-independent events driving muscle-specific alternative splicing has the potential to provide us with novel therapeutic strategies to treat different myopathies. Electronic supplementary material The online version of this article (10.1186/s13395-018-0152-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kiran Nakka
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada
| | - Claudia Ghigna
- Istituto di Genetica Molecolare-Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
| | - Davide Gabellini
- Unit of Gene Expression and Muscular Dystrophy, Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, DIBIT2, 5A3-44, via Olgettina 58, 20132, Milan, Italy.
| | - F Jeffrey Dilworth
- Sprott Centre for Stem Cell Research, Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, ON, K1H 8L6, Canada. .,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada. .,Sprott Centre for Stem Cell Research, Ottawa Hospital Research Institute, 501 Smyth Rd, Mailbox 511, Ottawa, ON, K1H 8L6, Canada.
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19
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Weskamp K, Barmada SJ. TDP43 and RNA instability in amyotrophic lateral sclerosis. Brain Res 2018; 1693:67-74. [PMID: 29395044 DOI: 10.1016/j.brainres.2018.01.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/09/2018] [Accepted: 01/12/2018] [Indexed: 12/13/2022]
Abstract
The nuclear RNA-binding protein TDP43 is integrally involved in RNA processing. In accord with this central function, TDP43 levels are tightly regulated through a negative feedback loop, in which TDP43 recognizes its own RNA transcript, destabilizes it, and reduces new TDP43 protein production. In the neurodegenerative disorder amyotrophic lateral sclerosis (ALS), cytoplasmic mislocalization and accumulation of TDP43 disrupt autoregulation; conversely, inefficient TDP43 autoregulation can lead to cytoplasmic TDP43 deposition and subsequent neurodegeneration. Because TDP43 plays a multifaceted role in maintaining RNA metabolism, its mislocalization and accumulation interrupt several RNA processing pathways that in turn affect RNA stability and gene expression. TDP43-mediated disruption of these pathways-including alternative mRNA splicing, non-coding RNA processing, and RNA granule dynamics-may directly or indirectly contribute to ALS pathogenesis. Therefore, strategies that restore effective TDP43 autoregulation may ultimately prevent neurodegeneration in ALS and related disorders.
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Affiliation(s)
- Kaitlin Weskamp
- Neuroscience Graduate Program and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States
| | - Sami J Barmada
- Neuroscience Graduate Program and Department of Neurology, University of Michigan School of Medicine, Ann Arbor, MI, United States.
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20
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Abstract
Solid tumors are composed of mutually interacting cancer cells and tumor microenvironment. Many environmental components, such as extracellular matrix (ECM), mesenchymal stem cells, endothelial and immune cells, and various growth factors and cytokines, provide signals, either stimulatory or inhibitory, to cancer cells and determine their fates. Meanwhile, cancer cells can also educate surrounding cells or tissues to undergo changes that are in favorable of tumor progression. CD44, as a transmembrane receptor for hyaluronic acid (HA) and many other ECM components and a coreceptor for growth factors and cytokines, is a critical cell surface molecule that can sense, integrate, and transduce cellular microenvironmental signals to membrane-associated cytoskeletal proteins or to cell nucleus to regulate a variety of gene expressions that govern cell behaviors. Mounting evidence suggests that CD44, particularly CD44v isoforms, are cancer stem cell (CSC) markers and critical regulators of cancer stemness, including self-renewal, tumor initiation, and metastasis. Thus, CD44 is widely used alone or in combination with other cell surface markers to isolate or enrich CSCs through fluorescence-activated cell sorting of dissociated single cells that originate from the patient, xenograft tumor tissues, or tumor cell cultures. Sorted cells are cultured in a specialized culture medium for spheroid formation or inoculated into immunodeficient mice for the analysis of tumorigenic or metastatic potential. In this chapter, detailed experimental methods regarding CD44+ tumor cell isolation, spheroid culture, and characterization will be described.
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Affiliation(s)
- Liang Wang
- Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Unit 1466, 1515 Holcombe Blvd, Houston, TX, 77030, USA
| | - Xiangsheng Zuo
- Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Unit 956, 1515 Holcombe Blvd, Houston, TX, 77030, USA
| | - Keping Xie
- Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Unit 1466, 1515 Holcombe Blvd, Houston, TX, 77030, USA
| | - Daoyan Wei
- Department of Gastroenterology, Hepatology and Nutrition, The University of Texas MD Anderson Cancer Center, Unit 1466, 1515 Holcombe Blvd, Houston, TX, 77030, USA.
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21
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Abstract
Ribonucleic acid (RNA) homeostasis is dynamically modulated in response to changing physiological conditions. Tight regulation of RNA abundance through both transcription and degradation determines the amount, timing, and location of protein translation. This balance is of particular importance in neurons, which are among the most metabolically active and morphologically complex cells in the body. As a result, any disruptions in RNA degradation can have dramatic consequences for neuronal health. In this chapter, we will first discuss mechanisms of RNA stabilization and decay. We will then explore how the disruption of these pathways can lead to neurodegenerative disease.
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22
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Signaling Pathways Driving Aberrant Splicing in Cancer Cells. Genes (Basel) 2017; 9:genes9010009. [PMID: 29286307 PMCID: PMC5793162 DOI: 10.3390/genes9010009] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/07/2017] [Accepted: 12/18/2017] [Indexed: 12/17/2022] Open
Abstract
Aberrant profiles of pre-mRNA splicing are frequently observed in cancer. At the molecular level, an altered profile results from a complex interplay between chromatin modifications, the transcriptional elongation rate of RNA polymerase, and effective binding of the spliceosome to the generated transcripts. Key players in this interplay are regulatory splicing factors (SFs) that bind to gene-specific splice-regulatory sequence elements. Although mutations in genes of some SFs were described, a major driver of aberrant splicing profiles is oncogenic signal transduction pathways. Signaling can affect either the transcriptional expression levels of SFs or the post-translational modification of SF proteins, and both modulate the ratio of nuclear versus cytoplasmic SFs in a given cell. Here, we will review currently known mechanisms by which cancer cell signaling, including the mitogen-activated protein kinases (MAPK), phosphatidylinositol 3 (PI3)-kinase pathway (PI3K) and wingless (Wnt) pathways but also signals from the tumor microenvironment, modulate the activity or subcellular localization of the Ser/Arg rich (SR) proteins and heterogeneous nuclear ribonucleoproteins (hnRNPs) families of SFs.
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23
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Ghatak S, Markwald RR, Hascall VC, Dowling W, Lottes RG, Baatz JE, Beeson G, Beeson CC, Perrella MA, Thannickal VJ, Misra S. Transforming growth factor β1 (TGFβ1) regulates CD44V6 expression and activity through extracellular signal-regulated kinase (ERK)-induced EGR1 in pulmonary fibrogenic fibroblasts. J Biol Chem 2017; 292:10465-10489. [PMID: 28389562 DOI: 10.1074/jbc.m116.752451] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 04/06/2017] [Indexed: 01/06/2023] Open
Abstract
The appearance of myofibroblasts is generally thought to be the underlying cause of the fibrotic changes that underlie idiopathic pulmonary fibrosis. However, the cellular/molecular mechanisms that account for the fibroblast-myofibroblast differentiation/activation in idiopathic pulmonary fibrosis remain poorly understood. We investigated the functional role of hyaluronan receptor CD44V6 (CD44 containing variable exon 6 (v6)) for differentiation of lung fibroblast to myofibroblast phenotype. Increased hyaluronan synthesis and CD44 expression have been detected in numerous fibrotic organs. Previously, we found that the TGFβ1/CD44V6 pathway is important in lung myofibroblast collagen-1 and α-smooth-muscle actin synthesis. Because increased EGR1 (early growth response-1) expression has been shown to appear very early and nearly coincident with the expression of CD44V6 found after TGFβ1 treatment, we investigated the mechanism(s) of regulation of CD44V6 expression in lung fibroblasts by TGFβ1. TGFβ1-mediated CD44V6 up-regulation was initiated through EGR1 via ERK-regulated transcriptional activation. We showed that TGFβ1-induced CD44V6 expression is through EGR1-mediated AP-1 (activator protein-1) activity and that the EGR1- and AP-1-binding sites in the CD44v6 promoter account for its responsiveness to TGFβ1 in lung fibroblasts. We also identified a positive-feedback loop in which ERK/EGR1 signaling promotes CD44V6 splicing and found that CD44V6 then sustains ERK signaling, which is important for AP-1 activity in lung fibroblasts. Furthermore, we identified that HAS2-produced hyaluronan is required for CD44V6 and TGFβRI co-localization and subsequent CD44V6/ERK1/EGR1 signaling. These results demonstrate a novel positive-feedback loop that links the myofibroblast phenotype to TGFβ1-stimulated CD44V6/ERK/EGR1 signaling.
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Affiliation(s)
- Shibnath Ghatak
- From the Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425,
| | - Roger R Markwald
- From the Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Vincent C Hascall
- the Department of Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio 44195
| | - William Dowling
- From the Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425.,the College of Charleston, Charleston, South Carolina 29424
| | | | | | - Gyada Beeson
- Drug Discovery and Biomedical sciences, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Craig C Beeson
- Drug Discovery and Biomedical sciences, Medical University of South Carolina, Charleston, South Carolina 29425
| | - Mark A Perrella
- the Division of Pulmonary and Critical Care Medicine, Department of Medicine, and the Department of Pediatric Newborn Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, and
| | - Victor J Thannickal
- the Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294-0006
| | - Suniti Misra
- From the Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina 29425,
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Kemler D, Dahley O, Roßwag S, Litfin M, Kassel O. The LIM domain protein nTRIP6 acts as a co-repressor for the transcription factor MEF2C in myoblasts. Sci Rep 2016; 6:27746. [PMID: 27292777 PMCID: PMC4904203 DOI: 10.1038/srep27746] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 05/23/2016] [Indexed: 12/17/2022] Open
Abstract
The transcription factor Myocyte enhancer factor 2C (MEF2C) plays a key role in the late differentiation of skeletal muscle progenitor cells, the so-called myoblasts. During myoblast differentiation, both MEF2C expression and transcriptional activity are regulated. We have reported that nTRIP6, the nuclear isoform of the focal adhesion LIM domain protein TRIP6, acts as an adaptor transcriptional co-activator for several transcription factors. It interacts with the promoter-bound transcription factors and consequently mediates the recruitment of other co-activators. Based on a described interaction between MEF2C and TRIP6 in a yeast-two-hybrid screen, we hypothesised a co-regulatory function of nTRIP6 for MEF2C. In proliferating myoblasts, nTRIP6 interacted with MEF2C and was recruited together with MEF2C to the MEF2-binding regions of the MEF2C target genes Myom2, Mb, Tnni2 and Des. Silencing nTRIP6 or preventing its interaction with MEF2C increased MEF2C transcriptional activity and increased the expression of these MEF2C target genes. Thus, nTRIP6 acts as a co-repressor for MEF2C. Mechanistically, nTRIP6 mediated the recruitment of the class IIa histone deacetylase HDAC5 to the MEF2C-bound promoters. In conclusion, our results unravel a transcriptional co-repressor function for nTRIP6. This adaptor co-regulator can thus exert either co-activator or co-repressor functions, depending on the transcription factor it interacts with.
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Affiliation(s)
- Denise Kemler
- Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics, Karlsruhe, Germany
| | - Oliver Dahley
- Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics, Karlsruhe, Germany
| | - Sven Roßwag
- Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics, Karlsruhe, Germany
| | - Margarethe Litfin
- Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics, Karlsruhe, Germany
| | - Olivier Kassel
- Karlsruhe Institute of Technology (KIT), Institute of Toxicology and Genetics, Karlsruhe, Germany
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The Role of Alternative Splicing in the Control of Immune Homeostasis and Cellular Differentiation. Int J Mol Sci 2015; 17:ijms17010003. [PMID: 26703587 PMCID: PMC4730250 DOI: 10.3390/ijms17010003] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 12/11/2015] [Accepted: 12/15/2015] [Indexed: 12/21/2022] Open
Abstract
Alternative splicing of pre-mRNA helps to enhance the genetic diversity within mammalian cells by increasing the number of protein isoforms that can be generated from one gene product. This provides a great deal of flexibility to the host cell to alter protein function, but when dysregulation in splicing occurs this can have important impact on health and disease. Alternative splicing is widely used in the mammalian immune system to control the development and function of antigen specific lymphocytes. In this review we will examine the splicing of pre-mRNAs yielding key proteins in the immune system that regulate apoptosis, lymphocyte differentiation, activation and homeostasis, and discuss how defects in splicing can contribute to diseases. We will describe how disruption to trans-acting factors, such as heterogeneous nuclear ribonucleoproteins (hnRNPs), can impact on cell survival and differentiation in the immune system.
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26
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Effect of CD44 gene polymorphisms on risk of transitional cell carcinoma of the urinary bladder in Taiwan. Tumour Biol 2015; 37:6971-7. [DOI: 10.1007/s13277-015-4566-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/01/2015] [Indexed: 10/22/2022] Open
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The splicing activator DAZAP1 integrates splicing control into MEK/Erk-regulated cell proliferation and migration. Nat Commun 2015; 5:3078. [PMID: 24452013 PMCID: PMC4146490 DOI: 10.1038/ncomms4078] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 12/06/2013] [Indexed: 01/15/2023] Open
Abstract
Alternative splicing of pre-messenger RNA (mRNA) is a critical stage of gene regulation in response to environmental stimuli. Here we show that DAZAP1, an RNA-binding protein involved in mammalian development and spermatogenesis, promotes inclusion of weak exons through specific recognition of diverse cis-elements. The carboxy-terminal proline-rich domain of DAZAP1 interacts with and neutralizes general splicing inhibitors, and is sufficient to activate splicing when recruited to pre-mRNA. This domain is phosphorylated by the MEK/Erk (extracellular signal-regulated protein kinase) pathway and this modification is essential for the splicing regulatory activity and the nuclear/cytoplasmic translocation of DAZAP1. Using mRNA-seq, we identify endogenous splicing events regulated by DAZAP1, many of which are involved in maintaining cell growth. Knockdown or over-expression of DAZAP1 causes a cell proliferation defect. Taken together, these studies reveal a molecular mechanism that integrates splicing control into MEK/Erk-regulated cell proliferation.
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28
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LOH TIINGJEN, MOON HEEGYUM, CHO SUNGHEE, JANG HANA, LIU YONGCHAO, TAI HONGMEI, JUNG DAWOON, WILLIAMS DARRENR, KIM HEYRAN, SHIN MYUNGGEUN, LIAO DJOSHUA, ZHOU JIANHUA, SHI WEI, ZHENG XUEXIU, SHEN HAIHONG. CD44 alternative splicing and hnRNP A1 expression are associated with the metastasis of breast cancer. Oncol Rep 2015; 34:1231-8. [DOI: 10.3892/or.2015.4110] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 05/20/2015] [Indexed: 11/06/2022] Open
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Lawrenson K, Mhawech-Fauceglia P, Worthington J, Spindler TJ, O'Brien D, Lee JM, Spain G, Sharifian M, Wang G, Darcy KM, Pejovic T, Sowter H, Timms JF, Gayther SA. Identification of novel candidate biomarkers of epithelial ovarian cancer by profiling the secretomes of three-dimensional genetic models of ovarian carcinogenesis. Int J Cancer 2015; 137:1806-17. [PMID: 25204737 DOI: 10.1002/ijc.29197] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 07/23/2014] [Accepted: 07/28/2014] [Indexed: 12/27/2022]
Abstract
Epithelial ovarian cancer (EOC) is still considered the most lethal gynecological malignancy and improved early detection of ovarian cancer is crucial to improving patient prognoses. To address this need, we tested whether candidate EOC biomarkers can be identified using three-dimensional (3D) in vitro models. We quantified changes in the abundance of secreted proteins in a 3D genetic model of early-stage EOC, generated by expressing CMYC and KRAS(G) (12) (V) in TERT-immortalized normal ovarian epithelial cells. Cellular proteins were labeled in live cells using stable isotopic amino acid analogues, and secreted proteins identified and quantified using liquid chromatography-tandem mass spectrometry. Thirty-seven and 55 proteins were differentially expressed by CMYC and CMYC+KRAS(G) (12) (V) expressing cells respectively (p < 0.05; >2-fold). We evaluated expression of the top candidate biomarkers in ∼210 primary EOCs: CHI3L1 and FKBP4 are both expressed by >96% of primary EOCs, and FASN and API5 are expressed by 86 and 75% of cases. High expression of CHI3L1 and FKBP4 was associated with worse patient survival (p = 0.042 and p = 0.002, respectively). Expression of LGALS3BP was positively associated with recurrence (p = 0.0001) and suboptimal debulking (p = 0.018) suggesting that these proteins may be novel prognostic biomarkers. Furthermore, within early stage tumours (I/II), high expression of API5, CHI3L1 and FASN was associated with high tumour grade (p = 3 × 10(-4) , p = 0.016, p = 0.010, respectively). We show in vitro cell biology models of early-stage cancer development can be used to identify novel candidate biomarkers for disease, and report the identification of proteins that represent novel potential candidate diagnostic and prognostic biomarkers for this highly lethal disease.
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Affiliation(s)
- Kate Lawrenson
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Paulette Mhawech-Fauceglia
- Departments of Medicine and Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Jenny Worthington
- Cancer Proteomics Group, Institute for Women's Health, University College London, London, United Kingdom
| | - Tassja J Spindler
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Darragh O'Brien
- Cancer Proteomics Group, Institute for Women's Health, University College London, London, United Kingdom
| | - Janet M Lee
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Georgia Spain
- Cancer Proteomics Group, Institute for Women's Health, University College London, London, United Kingdom
| | - Maryam Sharifian
- Departments of Medicine and Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Guisong Wang
- Women's Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale, VA
| | - Kathleen M Darcy
- Women's Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale, VA
| | - Tanja Pejovic
- Department of Obstetrics and Gynecology, Oregon Health and Science University, Portland, OR
| | - Heidi Sowter
- Biological and Forensic Science Department, University of Derby, Derby, United Kingdom
| | - John F Timms
- Cancer Proteomics Group, Institute for Women's Health, University College London, London, United Kingdom
| | - Simon A Gayther
- Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA
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Yan Y, Zuo X, Wei D. Concise Review: Emerging Role of CD44 in Cancer Stem Cells: A Promising Biomarker and Therapeutic Target. Stem Cells Transl Med 2015; 4:1033-43. [PMID: 26136504 DOI: 10.5966/sctm.2015-0048] [Citation(s) in RCA: 437] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 05/26/2015] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED The reception and integration of the plethora of signals a cell receives from its microenvironment determines the cell's fate. CD44 functions as a receptor for hyaluronan and many other extracellular matrix components, as well as a cofactor for growth factors and cytokines, and thus, CD44 is a signaling platform that integrates cellular microenvironmental cues with growth factor and cytokine signals and transduces signals to membrane-associated cytoskeletal proteins or to the nucleus to regulate a variety of gene expression levels related to cell-matrix adhesion, cell migration, proliferation, differentiation, and survival. Accumulating evidence indicates that CD44, especially CD44v isoforms, are cancer stem cell (CSC) markers and critical players in regulating the properties of CSCs, including self-renewal, tumor initiation, metastasis, and chemoradioresistance. Furthermore, there is ample evidence that CD44, especially CD44v isoforms, are valuable prognostic markers in various types of tumors. Therefore, therapies that target CD44 may destroy the CSC population, and this holds great promise for the cure of life-threatening cancers. However, many challenges remain to determining how best to use CD44 as a biomarker and therapeutic target. Here we summarize the current findings concerning the critical role of CD44/CD44v in the regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer. We also discuss the current challenges and future directions that may lead to the best use of CD44/CD44v for clinical applications. SIGNIFICANCE Mounting evidence indicates that cancer stem cells (CSCs) are mainly responsible for cancer aggressiveness, drug resistance, and tumor relapse. CD44, especially CD44v isoforms, have been identified as CSC surface markers for isolating and enriching CSCs in different types of cancers. The current findings concerning the critical role of CD44/CD44v in regulation of cancer stemness and the research status of CD44/CD44v as biomarkers and therapeutic targets in cancer are summarized. The current challenges and future directions that may lead to best use of CD44/CD44v for clinical applications are also discussed.
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Affiliation(s)
- Yongmin Yan
- Departments of Gastroenterology, Hepatology & Nutrition and Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA; School of Medical Sciences and Laboratory Medicine, Jiangsu University, Zhenjiang, People's Republic of China
| | - Xiangsheng Zuo
- Departments of Gastroenterology, Hepatology & Nutrition and Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA; School of Medical Sciences and Laboratory Medicine, Jiangsu University, Zhenjiang, People's Republic of China
| | - Daoyan Wei
- Departments of Gastroenterology, Hepatology & Nutrition and Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA; School of Medical Sciences and Laboratory Medicine, Jiangsu University, Zhenjiang, People's Republic of China
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Nuclear matrix-associated protein SMAR1 regulates alternative splicing via HDAC6-mediated deacetylation of Sam68. Proc Natl Acad Sci U S A 2015; 112:E3374-83. [PMID: 26080397 DOI: 10.1073/pnas.1418603112] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Pre-mRNA splicing is a complex regulatory nexus modulated by various trans-factors and their posttranslational modifications to create a dynamic transcriptome through alternative splicing. Signal-induced phosphorylation and dephosphorylation of trans-factors are known to regulate alternative splicing. However, the role of other posttranslational modifications, such as deacetylation/acetylation, methylation, and ubiquitination, that could modulate alternative splicing in either a signal-dependent or -independent manner remain enigmatic. Here, we demonstrate that Scaffold/matrix-associated region-binding protein 1 (SMAR1) negatively regulates alternative splicing through histone deacetylase 6 (HDAC6)-mediated deacetylation of RNA-binding protein Sam68 (Src-associated substrate during mitosis of 68 kDa). SMAR1 is enriched in nuclear splicing speckles and associates with the snRNAs that are involved in splice site recognition. ERK-MAPK pathway that regulates alternative splicing facilitates ERK-1/2-mediated phosphorylation of SMAR1 at threonines 345 and 360 and localizes SMAR1 to the cytoplasm, preventing its interaction with Sam68. We showed that endogenously, SMAR1 through HDAC6 maintains Sam68 in a deacetylated state. However, knockdown or ERK-mediated phosphorylation of SMAR1 releases the inhibitory SMAR1-HDAC6-Sam68 complex, facilitating Sam68 acetylation and alternative splicing. Furthermore, loss of heterozygosity at the Chr.16q24.3 locus in breast cancer cells, wherein the human homolog of SMAR1 (BANP) has been mapped, enhances Sam68 acetylation and CD44 variant exon inclusion. In addition, tail-vein injections in mice with human breast cancer MCF-7 cells depleted for SMAR1 showed increased CD44 variant exon inclusion and concomitant metastatic propensity, confirming the functional role of SMAR1 in regulation of alternative splicing. Thus, our results reveal the complex molecular mechanism underlying SMAR1-mediated signal-dependent and -independent regulation of alternative splicing via Sam68 deacetylation.
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Dang H, Steinway SN, Ding W, Rountree CB. Induction of tumor initiation is dependent on CD44s in c-Met⁺ hepatocellular carcinoma. BMC Cancer 2015; 15:161. [PMID: 25886575 PMCID: PMC4380258 DOI: 10.1186/s12885-015-1166-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 03/05/2015] [Indexed: 12/16/2022] Open
Abstract
Background Hepatocellular carcinoma (HCC) patients with active hepatocyte growth factor (HGF)/c-Met signaling have a significantly worse prognosis. c-Met, a high affinity receptor for HGF, plays a critical role in cancer growth, invasion and metastasis. c-Met and CD44 have been utilized as cell surface markers to identify mesenchymal tumor-initiating stem-like cells (TISC) in several cancers including HCC. In this work, we examine the complex relationship between c-Met and CD44s (standard form), and investigate the specific role of CD44s as a tumor initiator and stemness marker in HCC. Methods Gene and protein expression assays were utilized to investigate the relationship between CD44s and c-Met in HCC cell lines. Tumor-sphere assays and in vivo tumor assays were performed to investigate the role of CD44+ cells as TISCs. Student’s t-test or one-way ANOVA with Tukeys post-hoc test was performed to test for differences amongst groups with a p < .05 as significant. Results In an immunohistochemical and immunoblot analysis of human HCC samples, we observed that more than 39% of human HCC samples express c-Met and CD44. To study the relationship between c-Met and CD44, we used MHCC97-H cells, which are CD44+/c-Met+. The knockdown of c-Met in MHCC97-H cells decreased CD44s, reduced TISC characteristics and decreased tumorsphere formation. Furthermore, we demonstrate that the inhibition of PI3K/AKT signaling decreased CD44s expression and subsequently decreased tumorsphere formation. The down-regulation of CD44s leads to a significant loss of a TISC and mesenchymal phenotype. Finally, the down-regulation of CD44s in MHCC97-H cells decreased tumor initiation in vivo compared with the scrambled control. Conclusions In summary, our data suggest that CD44s is modulated by the c-Met-PI3K-AKT signaling cascade to support a mesenchymal and TISC phenotype in HCC cells. Moreover, c-Met could be a potential therapeutic drug for targeting HCC cells with TISC and mesenchymal phenotypes. Electronic supplementary material The online version of this article (doi:10.1186/s12885-015-1166-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hien Dang
- Department of Pediatrics and Pharmacology, The Pennsylvania State University, College of Medicine, Penn State Children's Hospital, Hershey, PA, USA. .,Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, 37 Convent Drive, Bethesda, MD, 20892, USA.
| | - Steven N Steinway
- Department of Pediatrics and Pharmacology, The Pennsylvania State University, College of Medicine, Penn State Children's Hospital, Hershey, PA, USA.
| | - Wei Ding
- Department of Pediatrics and Pharmacology, The Pennsylvania State University, College of Medicine, Penn State Children's Hospital, Hershey, PA, USA.
| | - Carl B Rountree
- Department of Pediatrics and Pharmacology, The Pennsylvania State University, College of Medicine, Penn State Children's Hospital, Hershey, PA, USA. .,Bon Secours St. Mary's Hospital, 5875 Bremo Road, MOB South Suite 303, Richmond, VA, 23226, USA.
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Romanov VS, Brichkina AI, Morrison H, Pospelova TV, Pospelov VA, Herrlich P. Novel mechanism of JNK pathway activation by adenoviral E1A. Oncotarget 2015; 5:2176-86. [PMID: 24742962 PMCID: PMC4039154 DOI: 10.18632/oncotarget.1860] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The adenoviral oncoprotein E1A influences cellular regulation by interacting with a number of cellular proteins. In collaboration with complementary oncogenes, E1A fully transforms primary cells. As part of this action, E1A inhibits transcription of c-Jun:Fos target genes while promoting that of c-Jun:ATF2-dependent genes including jun. Both c-Jun and ATF2 are hyperphosphorylated in response to E1A. In the current study, E1A was fused with the ligand binding domain of the estrogen receptor (E1A-ER) to monitor the immediate effect of E1A activation. With this approach we now show that E1A activates c-Jun N-terminal kinase (JNK), the upstream kinases MKK4 and MKK7, as well as the small GTPase Rac1. Activation of the JNK pathway requires the N-terminal domain of E1A, and, importantly, is independent of transcription. In addition, it requires the presence of ERM proteins. Downregulation of signaling components upstream of JNK inhibits E1A-dependent JNK/c-Jun activation. Taking these findings together, we show that E1A activates the JNK/c-Jun signaling pathway upstream of Rac1 in a transcription-independent manner, demonstrating a novel mechanism of E1A action.
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Affiliation(s)
- Vasily S Romanov
- Leibniz Institute for Age Research - Fritz Lipmann Institute (FLI), Beutenbergstr. 11, D-07745 Jena, Germany
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CD44 gene polymorphisms on hepatocellular carcinoma susceptibility and clinicopathologic features. BIOMED RESEARCH INTERNATIONAL 2014; 2014:231474. [PMID: 24971320 PMCID: PMC4058263 DOI: 10.1155/2014/231474] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 05/13/2014] [Accepted: 05/15/2014] [Indexed: 12/12/2022]
Abstract
Hepatocellular carcinoma (HCC) is the second leading cause of cancer deaths in Taiwan. CD44, one of the well-known tumor markers, plays an essential role in tumor cell differentiation, invasion, and metastasis. We investigated the CD44 single-nucleotide polymorphisms (SNPs) with environmental risk factors related to HCC susceptibility and clinicopathological characteristics. Six SNPs of CD44 were analyzed using a real-time polymerase chain reaction (PCR) in 203 patients with HCC and in 561 cancer-free controls. We determined that the individuals carrying at least one G allele at CD44 rs187115 has higher risk of developing HCC than did wild-type (AA) carriers. We further observed that the CD44 rs187115 polymorphisms with at least one G allele had a higher frequency of distribution in nonsmoking stage III/IV HCC patients, compared with wild-type carriers. Our results suggested that patients with CD44 rs187115 variant genotypes (AG+GG) were associated with a higher risk of HCC development and that these patients might possess chemoresistance, causing more likely progression to late-stage HCC than wild-type carriers without the overexpression of CD44 induced by heavy smoking. CD44 rs187115 might be involved in CD44 isoform expression of p53 stress response in HCC and provide a marker for predicting worst-case prognosis of HCC.
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The LIM domain protein nTRIP6 recruits the mediator complex to AP-1-regulated promoters. PLoS One 2014; 9:e97549. [PMID: 24819052 PMCID: PMC4018362 DOI: 10.1371/journal.pone.0097549] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/18/2014] [Indexed: 01/25/2023] Open
Abstract
Several LIM domain proteins regulate transcription. They are thought to act through their LIM protein-protein interaction domains as adaptors for the recruitment of transcriptional co-regulators. An intriguing example is nTRIP6, the nuclear isoform of the focal adhesion protein TRIP6. nTRIP6 interacts with AP-1 and enhances its transcriptional activity. nTRIP6 is also essential for the transrepression of AP-1 by the glucocorticoid receptor (GR), by mediating GR tethering to promoter-bound AP-1. Here we report on the molecular mechanism by which nTRIP6 exerts these effects. Both the LIM domains and the pre-LIM region of nTRIP6 are necessary for its co-activator function for AP-1. Discrete domains within the pre-LIM region mediate the dimerization of nTRIP6 at the promoter, which enables the recruitment of the Mediator complex subunits THRAP3 and Med1. This recruitment is blocked by GR, through a competition between GR and THRAP3 for the interaction with the LIM domains of nTRIP6. Thus, nTRIP6 both positively and negatively regulates transcription by orchestrating the recruitment of the Mediator complex to AP-1-regulated promoters.
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Chou YE, Hsieh MJ, Hsin CH, Chiang WL, Lai YC, Lee YH, Huang SC, Yang SF, Lin CW. CD44 gene polymorphisms and environmental factors on oral cancer susceptibility in Taiwan. PLoS One 2014; 9:e93692. [PMID: 24699672 PMCID: PMC3974805 DOI: 10.1371/journal.pone.0093692] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 03/09/2014] [Indexed: 12/20/2022] Open
Abstract
Background Oral squamous cell carcinoma (OSCC) is the fourth leading cause of male cancer death in Taiwan. Exposure to environmental carcinogens is the primary risk factor for developing OSCC. CD44, a well-known tumor marker, plays a crucial role in tumor cell differentiation, invasion, and metastasis. This study investigated CD44 single-nucleotide polymorphisms (SNPs) with environmental risk factors to determine OSCC susceptibility and clinicopathological characteristics. Methodology/Principal Findings Real-time polymerase chain reaction (PCR) was used to analyze 6 SNPs of CD44 in 599 patients with oral cancer and 561 cancer-free controls. We determined that the CD44 rs187115 polymorphism carriers with the genotype AG, GG, or AG+GG were associated with oral cancer susceptibility. Among 731 smokers, CD44 polymorphisms carriers with the betel-nut chewing habit had a 10.30–37.63-fold greater risk of having oral cancer compared to CD44 wild-type (WT) carriers without the betel-nut chewing habit. Among 552 betel-nut chewers, CD44 polymorphisms carriers who smoked had a 4.23–16.11-fold greater risk of having oral cancer compared to those who carried the WT but did not smoke. Finally, we also observed that the stage III and IV oral cancer patients had higher frequencies of CD44 rs187115 polymorphisms with the variant genotype (AG+GG) compared with the wild-type (WT) carriers. Conclusion Our results suggest that gene–environment interactions between the CD44 polymorphisms and betel quid chewing and tobacco smoking increase the susceptibility to oral cancer development. Patients with CD44 rs187115 variant genotypes (AG+GG) were correlated with a higher risk of oral cancer development, and these patients may possess greater chemoresistance to advanced- to late-stage oral cancer than WT carriers do. The CD44 rs187115 polymorphism has potential predictive significance in oral carcinogenesis and also may be applied as factors to predict the clinical stage in OSCC patients.
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Affiliation(s)
- Ying-Erh Chou
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Ming-Ju Hsieh
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Cancer Research Center, Changhua Christian Hospital, Changhua, Taiwan
| | - Chung-Han Hsin
- School of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Department of Otolaryngology, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Whei-Ling Chiang
- School of Medical Laboratory and Biotechnology, Chung Shan Medical University, Taichung, Taiwan
| | - Yi-Cheng Lai
- School of Dentistry, Chung Shan Medical University, Taichung, Taiwan
| | - Yu-Hsien Lee
- School of Dentistry, Chung Shan Medical University, Taichung, Taiwan
- Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Shu-Ching Huang
- School of Dentistry, Chung Shan Medical University, Taichung, Taiwan
- Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Shun-Fa Yang
- Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan
- Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan
| | - Chiao-Wen Lin
- Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan
- Institute of Oral Sciences, Chung Shan Medical University, Taichung, Taiwan
- * E-mail:
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Gonçalves V, Henriques A, Pereira J, Neves Costa A, Moyer MP, Moita LF, Gama-Carvalho M, Matos P, Jordan P. Phosphorylation of SRSF1 by SRPK1 regulates alternative splicing of tumor-related Rac1b in colorectal cells. RNA (NEW YORK, N.Y.) 2014; 20:474-82. [PMID: 24550521 PMCID: PMC3964909 DOI: 10.1261/rna.041376.113] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/07/2014] [Indexed: 05/28/2023]
Abstract
The premessenger RNA of the majority of human genes can generate various transcripts through alternative splicing, and different tissues or disease states show specific patterns of splicing variants. These patterns depend on the relative concentrations of the splicing factors present in the cell nucleus, either as a consequence of their expression levels or of post-translational modifications, such as protein phosphorylation, which are determined by signal transduction pathways. Here, we analyzed the contribution of protein kinases to the regulation of alternative splicing variant Rac1b that is overexpressed in certain tumor types. In colorectal cells, we found that depletion of AKT2, AKT3, GSK3β, and SRPK1 significantly decreased endogenous Rac1b levels. Although knockdown of AKT2 and AKT3 affected only Rac1b protein levels suggesting a post-splicing effect, the depletion of GSK3β or SRPK1 decreased Rac1b alternative splicing, an effect mediated through changes in splicing factor SRSF1. In particular, the knockdown of SRPK1 or inhibition of its catalytic activity reduced phosphorylation and subsequent translocation of SRSF1 to the nucleus, limiting its availability to promote the inclusion of alternative exon 3b into the Rac1 pre-mRNA. Altogether, the data identify SRSF1 as a prime regulator of Rac1b expression in colorectal cells and provide further mechanistic insight into how the regulation of alternative splicing events by protein kinases can contribute to sustain tumor cell survival.
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Affiliation(s)
- Vânia Gonçalves
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Andreia Henriques
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Joana Pereira
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Ana Neves Costa
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | | | - Luís Ferreira Moita
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Margarida Gama-Carvalho
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Paulo Matos
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Peter Jordan
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
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Oana K, Oma Y, Suo S, Takahashi MP, Nishino I, Takeda S, Ishiura S. Manumycin A corrects aberrant splicing of Clcn1 in myotonic dystrophy type 1 (DM1) mice. Sci Rep 2013; 3:2142. [PMID: 23828222 PMCID: PMC3701899 DOI: 10.1038/srep02142] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 05/17/2013] [Indexed: 01/12/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is the most common muscular dystrophy in adults and as yet no cure for DM1. Here, we report the potential of manumycin A for a novel DM1 therapeutic reagent. DM1 is caused by expansion of CTG repeat. Mutant transcripts containing expanded CUG repeats lead to aberrant regulation of alternative splicing. Myotonia (delayed muscle relaxation) is the most commonly observed symptom in DM1 patients and is caused by aberrant splicing of the skeletal muscle chloride channel (CLCN1) gene. Identification of small-molecule compounds that correct aberrant splicing in DM1 is attracting much attention as a way of improving understanding of the mechanism of DM1 pathology and improving treatment of DM1 patients. In this study, we generated a reporter screening system and searched for small-molecule compounds. We found that manumycin A corrects aberrant splicing of Clcn1 in cell and mouse models of DM1.
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Affiliation(s)
- Kosuke Oana
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Tokyo, Japan
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Liu H, Tang L. Mechano-regulation of alternative splicing. Curr Genomics 2013; 14:49-55. [PMID: 23997650 PMCID: PMC3580779 DOI: 10.2174/138920213804999156] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 11/22/2012] [Accepted: 12/23/2012] [Indexed: 01/29/2023] Open
Abstract
Alternative splicing contributes to the complexity of proteome by producing multiple mRNAs from a single gene. Affymetrix exon arrays and experiments in vivo or in vitro demonstrated that alternative splicing was regulated by mechanical stress. Expression of mechano-growth factor (MGF) which is the splicing isoform of insulin-like growth factor 1(IGF-1) and vascular endothelial growth factor (VEGF) splicing variants such as VEGF121, VEGF165, VEGF206, VEGF189, VEGF165 and VEGF145 are regulated by mechanical stress. However, the mechanism of this process is not yet clear. Increasing evidences showed that the possible mechanism is related to Ca2+ signal pathway and phosphorylation signal pathway. This review proposes possible mechanisms of mechanical splicing regulation. This will contribute to the biomechanical study of alternative splicing.
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Affiliation(s)
- Huan Liu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, China
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Liu S, Cheng C. Alternative RNA splicing and cancer. WILEY INTERDISCIPLINARY REVIEWS. RNA 2013; 4:547-66. [PMID: 23765697 PMCID: PMC4426271 DOI: 10.1002/wrna.1178] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2013] [Revised: 05/10/2013] [Accepted: 05/11/2013] [Indexed: 01/04/2023]
Abstract
Alternative splicing of pre-messenger RNA (mRNA) is a fundamental mechanism by which a gene can give rise to multiple distinct mRNA transcripts, yielding protein isoforms with different, even opposing, functions. With the recognition that alternative splicing occurs in nearly all human genes, its relationship with cancer-associated pathways has emerged as a rapidly growing field. In this review, we summarize recent findings that have implicated the critical role of alternative splicing in cancer and discuss current understandings of the mechanisms underlying dysregulated alternative splicing in cancer cells.
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Affiliation(s)
- Sali Liu
- Department of Medicine, Robert H. Lurie Comprehensive Cancer Center, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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Combined inhibition of PI3K and activation of MAPK p38 signaling pathways trigger erythroid alternative splicing switch of 4.1R pre-mRNA in DMSO-induced erythroleukemia cells. Cell Signal 2013; 25:2453-61. [PMID: 23993958 DOI: 10.1016/j.cellsig.2013.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 08/23/2013] [Indexed: 01/09/2023]
Abstract
There is increasing evidence showing that many extracellular cues modulate pre-mRNA alternative splicing, through different signaling pathways. We here show that 4.1R exon 16 splicing is altered in response to specific signals. The switch from erythroblastic isoform lacking exon 16 to mature erythrocytic isoform containing this exon is tightly regulated during late erythroid differentiation, and blocage of this splicing switch in erythroleukemia cells is seen as a consequence of the deregulation of important regulatory pathways. We support that combined inhibition of PI3K and activation of p38 signaling pathways impinge on erythroid 4.1R pre-mRNA alternative splicing switch, and on cell differentiation as witnessed by hemoglobin production. By contrast, MEK/ERK signaling appeared not to affect neither cell hemoglobin production nor erythroid 4.1R pre-mRNA splicing. We also found that the signal-induced alternative splicing is not typically distinctive of EPO-non-responsive cells, but operates in EPO-responsive cells as well. Pre-mRNA splicing is a major regulatory mechanism at the crossroad between transcription and translation. We here provide evidence that inhibition of PI3K activates the splicing switch in a promoter-dependent manner, whereas p38 activation induces this event in a promoter-independent fashion. Our data further support that constitutive activation of EPO-R by the viral protein gp55 and the short form of the tyrosine kinase receptor Stk, transduces PI3K proliferation signal, but not MAPK p38 differentiation signal. Concurrently, this work lend credence to the concept that DMSO triggers transient activation of p38 signaling and irreversible inhibition of PI3K/AKT signaling pathway, hence uncovering an old conundrum regarding the mechanism by which DMSO induces erythroleukemia cell differentiation.
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Naro C, Sette C. Phosphorylation-mediated regulation of alternative splicing in cancer. Int J Cell Biol 2013; 2013:151839. [PMID: 24069033 PMCID: PMC3771450 DOI: 10.1155/2013/151839] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/26/2013] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing (AS) is one of the key processes involved in the regulation of gene expression in eukaryotic cells. AS catalyzes the removal of intronic sequences and the joining of selected exons, thus ensuring the correct processing of the primary transcript into the mature mRNA. The combinatorial nature of AS allows a great expansion of the genome coding potential, as multiple splice-variants encoding for different proteins may arise from a single gene. Splicing is mediated by a large macromolecular complex, the spliceosome, whose activity needs a fine regulation exerted by cis-acting RNA sequence elements and trans-acting RNA binding proteins (RBP). The activity of both core spliceosomal components and accessory splicing factors is modulated by their reversible phosphorylation. The kinases and phosphatases involved in these posttranslational modifications significantly contribute to AS regulation and to its integration in the complex regulative network that controls gene expression in eukaryotic cells. Herein, we will review the major canonical and noncanonical splicing factor kinases and phosphatases, focusing on those whose activity has been implicated in the aberrant splicing events that characterize neoplastic transformation.
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Affiliation(s)
- Chiara Naro
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Laboratories of Neuroembryology and of Cellular and Molecular Neurobiology, Fondazione Santa Lucia IRCCS, 00143 Rome, Italy
| | - Claudio Sette
- Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, 00133 Rome, Italy
- Laboratories of Neuroembryology and of Cellular and Molecular Neurobiology, Fondazione Santa Lucia IRCCS, 00143 Rome, Italy
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Hubert CG, Bradley RK, Ding Y, Toledo CM, Herman J, Skutt-Kakaria K, Girard EJ, Davison J, Berndt J, Corrin P, Hardcastle J, Basom R, Delrow JJ, Webb T, Pollard SM, Lee J, Olson JM, Paddison PJ. Genome-wide RNAi screens in human brain tumor isolates reveal a novel viability requirement for PHF5A. Genes Dev 2013; 27:1032-45. [PMID: 23651857 DOI: 10.1101/gad.212548.112] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
To identify key regulators of human brain tumor maintenance and initiation, we performed multiple genome-wide RNAi screens in patient-derived glioblastoma multiforme (GBM) stem cells (GSCs). These screens identified the plant homeodomain (PHD)-finger domain protein PHF5A as differentially required for GSC expansion, as compared with untransformed neural stem cells (NSCs) and fibroblasts. Given PHF5A's known involvement in facilitating interactions between the U2 snRNP complex and ATP-dependent helicases, we examined cancer-specific roles in RNA splicing. We found that in GSCs, but not untransformed controls, PHF5A facilitates recognition of exons with unusual C-rich 3' splice sites in thousands of essential genes. PHF5A knockdown in GSCs, but not untransformed NSCs, astrocytes, or fibroblasts, inhibited splicing of these genes, leading to cell cycle arrest and loss of viability. Notably, pharmacologic inhibition of U2 snRNP activity phenocopied PHF5A knockdown in GSCs and also in NSCs or fibroblasts overexpressing MYC. Furthermore, PHF5A inhibition compromised GSC tumor formation in vivo and inhibited growth of established GBM patient-derived xenograft tumors. Our results demonstrate a novel viability requirement for PHF5A to maintain proper exon recognition in brain tumor-initiating cells and may provide new inroads for novel anti-GBM therapeutic strategies.
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Affiliation(s)
- Christopher G Hubert
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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44
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Martinez NM, Lynch KW. Control of alternative splicing in immune responses: many regulators, many predictions, much still to learn. Immunol Rev 2013; 253:216-36. [PMID: 23550649 PMCID: PMC3621013 DOI: 10.1111/imr.12047] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Most mammalian pre-mRNAs are alternatively spliced in a manner that alters the resulting open reading frame. Consequently, alternative pre-mRNA splicing provides an important RNA-based layer of protein regulation and cellular function. The ubiquitous nature of alternative splicing coupled with the advent of technologies that allow global interrogation of the transcriptome have led to an increasing awareness of the possibility that widespread changes in splicing patterns contribute to lymphocyte function during an immune response. Indeed, a few notable examples of alternative splicing have clearly been demonstrated to regulate T-cell responses to antigen. Moreover, several proteins key to the regulation of splicing in T cells have recently been identified. However, much remains to be done to truly identify the spectrum of genes that are regulated at the level of splicing in immune cells and to determine how many of these are controlled by currently known factors and pathways versus unknown mechanisms. Here, we describe the proteins, pathways, and mechanisms that have been shown to regulate alternative splicing in human T cells and discuss what is and is not known about the genes regulated by such factors. Finally, we highlight unifying themes with regards to the mechanisms and consequences of alternative splicing in the adaptive immune system and give our view of important directions for future studies.
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Affiliation(s)
- Nicole M Martinez
- Department of Biochemistry and Biophysics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104-6059, USA
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45
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Abstract
Kras-induced non-small-cell lung adenocarcinoma is the major subtype of lung cancers and is associated with poor prognosis. Using a lung cancer mouse model that expresses a cre-mediated KrasG12D mutant, we identified a critical role for the cell surface molecule CD44 in mediating cell proliferation downstream of oncogenic Kras signaling. The deletion of CD44 attenuates lung adenocarcinoma formation and prolongs the survival of these mice. Mechanistically, CD44 is required for the activation of Kras-mediated signaling through the mitogen-activated protein kinase (MAPK) pathway and thus promotes tumor cell proliferation. Together, these results reveal an unrecognized role for CD44 in oncogenic Kras-induced lung adenocarcinoma and suggest that targeting CD44 could be an effective strategy for halting Kras-dependent carcinomas.
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46
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Rein-Smith CM, Anderson NW, Farrell DH. Differential regulation of fibrinogen γ chain splice isoforms by interleukin-6. Thromb Res 2012; 131:89-93. [PMID: 23036532 DOI: 10.1016/j.thromres.2012.09.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 09/14/2012] [Accepted: 09/20/2012] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Fibrinogen is a major structural protein in blood clots, and is also a well-known acute phase reactant. The γ chain gene of fibrinogen has two alternative splice variants, γA and γ' chains. γ' fibrinogen constitutes about 7% of total fibrinogen. Total fibrinogen levels and γ' fibrinogen levels have been associated with cardiovascular disease, but the mechanisms regulating the production of the two isoforms are unknown. Several inflammatory cytokines are known to influence the production of total fibrinogen, but the role of cytokines in the production of γ' fibrinogen has not been examined. However, epidemiologic studies have shown an association between γ' fibrinogen levels and inflammatory markers in humans. MATERIALS AND METHODS The expression of γ' fibrinogen and total fibrinogen by HepG2 liver cells was quantitated after treatment with interleukin-1β, transforming growth factor-β, tumor necrosis factor-α, and interleukin-6. RESULTS Interleukin-1β, transforming growth factor-β, and tumor necrosis factor-α, known down-regulators of total fibrinogen synthesis, also downregulate γ' fibrinogen synthesis in HepG2 cells. However, interleukin-6 differentially up-regulates the production of total and γ' fibrinogen, leading to a 3.6-fold increase in γA mRNA, but an 8.3-fold increase in γ' mRNA. CONCLUSIONS These findings indicate that γ' fibrinogen is disproportionately up-regulated by inflammatory responses induced by interleukin-6.
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Affiliation(s)
- Chantelle M Rein-Smith
- Department of Molecular and Medical Genetics, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA
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Arslan AD, He X, Wang M, Rumschlag-Booms E, Rong L, Beck WT. A high-throughput assay to identify small-molecule modulators of alternative pre-mRNA splicing. ACTA ACUST UNITED AC 2012; 18:180-90. [PMID: 22972848 DOI: 10.1177/1087057112459901] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Alternative splicing (AS) is an efficient mechanism that involves the generation of transcriptome and protein diversity from a single gene. Defects in pre-messenger RNA (mRNA) splicing are an important cause of numerous diseases, including cancer. AS of pre-mRNA as a target for cancer therapy has not been well studied. We have reported previously that a splicing factor, polypyrimidine tract-binding protein (PTB), is overexpressed in ovarian tumors compared with matched normal controls, and knockdown of PTB expression by short-hairpin RNA impairs ovarian tumor cell growth, colony formation, and invasiveness. Given the complexity of PTB's molecular functions, a chemical method for controlling PTB activity might provide a therapeutic and experimental tool. However, no commercially available PTB inhibitors have yet been described. To expand our ability to find novel inhibitors, we developed a robust, fluorometric, cell-based high-throughput screening assay in 96-well plates that reports on the splicing activity of PTB. In an attempt to use the cells for large-scale chemical screens to identify PTB modulators, we established cell lines stably expressing the reporter gene. Our results suggest that this high-throughput assay could be used to identify small-molecule modulators of PTB activity. Based on these findings and the role that upregulated PTB has on cell proliferation and malignant properties of tumors, targeting PTB for inhibition with small molecules offers a promising strategy for cancer therapy.
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Affiliation(s)
- Ahmet Dirim Arslan
- Department of Biopharmaceutical Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA
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Muñoz Ú, Puche JE, Hannivoort R, Lang UE, Cohen-Naftaly M, Friedman SL. Hepatocyte growth factor enhances alternative splicing of the Kruppel-like factor 6 (KLF6) tumor suppressor to promote growth through SRSF1. Mol Cancer Res 2012; 10:1216-27. [PMID: 22859706 DOI: 10.1158/1541-7786.mcr-12-0213] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Alternative splicing of the Krüppel-like factor 6 (KLF6) tumor suppressor into an antagonistic splice variant 1 (SV1) is a pathogenic event in several cancers including hepatocellular carcinoma (HCC) because elevated SV1 is associated with increased tumor metastasis and mortality. Ras activation is one factor that can enhance KLF6 splicing in cancer cells, however pathways driving KLF6 splicing are unknown. Splice site selection is regulated by splice factors that include serine/arginine-rich (SR) proteins such as SRSF1 (ASF-SF2), which in turn is controlled by phosphoinositide 3-kinase (PI3K)/Akt and the mitogen-activated protein kinase (MAPK) signaling pathway. Because signaling pathways downstream of the liver mitogen hepatocyte growth factor (HGF) include Akt, we explored whether HGF induces KLF6 alternative splicing. In HepG2 cells, HGF (25 ng/mL) significantly increases the ratio of SV1/KLF6 full by 40% through phosphorylation of Akt and subsequent downregulation of two splicing regulators, SRSF3 (SRp20) and SRSF1. Decreased SRSF3 levels regulate SRSF1 levels by alternative splicing associated with the nonsense-mediated mRNA decay pathway (AS-NMD), which stimulates cell growth by decreasing p21 levels. Enhanced cell replication through increased KLF6 alternative splicing is a novel growth-promoting pathway of HGF that could contribute to the molecule's mitogenic activity in physiologic liver growth and hepatocellular carcinoma.
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Affiliation(s)
- Úrsula Muñoz
- Division of Liver Diseases, Mount Sinai School of Medicine, New York, NY 10029, USA
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The Akt-SRPK-SR axis constitutes a major pathway in transducing EGF signaling to regulate alternative splicing in the nucleus. Mol Cell 2012; 47:422-33. [PMID: 22727668 DOI: 10.1016/j.molcel.2012.05.014] [Citation(s) in RCA: 199] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 04/09/2012] [Accepted: 05/10/2012] [Indexed: 11/21/2022]
Abstract
Pre-mRNA splicing is regulated by developmental and environmental cues, but little is known about how specific signals are transduced in mammalian cells to regulate this critical gene expression step. Here, we report massive reprogramming of alternative splicing in response to EGF signaling. By blocking individual branches in EGF signaling, we found that Akt activation plays a major role, while other branches, such as the JAK/STAT and ERK pathways, make minor contributions to EGF-induced splicing. Activated Akt next branches to SR protein-specific kinases, rather than mTOR, by inducing SRPK autophosphorylation that switches the splicing kinases from Hsp70- to Hsp90-containing complexes. This leads to enhanced SRPK nuclear translocation and SR protein phosphorylation. These findings reveal a major signal transduction pathway for regulated splicing and place SRPKs in a central position in the pathway, consistent with their reputed roles in a large number of human cancers.
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50
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Mitogen-activated protein kinase phosphorylation of splicing factor 45 (SPF45) regulates SPF45 alternative splicing site utilization, proliferation, and cell adhesion. Mol Cell Biol 2012; 32:2880-93. [PMID: 22615491 DOI: 10.1128/mcb.06327-11] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The regulation of alternative mRNA splicing factors by extracellular cues and signal transduction cascades is poorly understood. Using an engineered extracellular signal-regulated kinase 2 (ERK2) that can utilize ATP analogs, we have identified the alternative mRNA splicing factor 45 (SPF45), which is overexpressed in cancer, as a novel coimmunoprecipitating ERK2 substrate. ERK2 phosphorylated SPF45 on Thr71 and Ser222 in vitro and in cells in response to H-RasV12, B-RAF-V600E, and activated MEK1. Jun N-terminal kinase 1 (JNK1) and p38α also phosphorylated SPF45 in vitro and associated with SPF45 in cells. SPF45 was differentially phosphorylated in cells by all three mitogen-activated protein (MAP) kinases in response to phorbol myristate acid (PMA), H(2)O(2), UV, and anisomycin stimulation. ERK and p38 activation decreased SPF45-dependent exon 6 exclusion from fas mRNA in a minigene assay in cells. Stable overexpression of SPF45 in SKOV-3 cells dramatically inhibited cell proliferation in a phosphorylation-dependent manner through inhibition of ErbB2 expression. SPF45 overexpression also induced EDA inclusion into fibronectin transcripts and fibronectin expression in a phosphorylation-dependent and -independent manner, respectively, specifically affecting cellular adhesion to a fibronectin matrix. These data identify SPF45 as the first splicing factor regulated by multiple MAP kinase pathways and show effects of both SPF45 overexpression and phosphorylation.
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