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Fu AB, Xiang SF, He QJ, Ying MD. Kelch-like proteins in the gastrointestinal tumors. Acta Pharmacol Sin 2023; 44:931-939. [PMID: 36266566 PMCID: PMC10104798 DOI: 10.1038/s41401-022-01007-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 09/22/2022] [Indexed: 11/08/2022] Open
Abstract
Gastrointestinal tumors have become a worldwide health problem with high morbidity and poor clinical outcomes. Chemotherapy and surgery, the main treatment methods, are still far from meeting the treatment needs of patients, and targeted therapy is in urgent need of development. Recently, emerging evidence suggests that kelch-like (KLHL) proteins play essential roles in maintaining proteostasis and are involved in the progression of various cancers, functioning as adaptors in the E3 ligase complex and promoting the specific degradation of substrates. Therefore, KLHL proteins should be taken into consideration for targeted therapy strategy discovery. This review summarizes the current knowledge of KLHL proteins in gastrointestinal tumors and discusses the potential of KLHL proteins as potential drug targets and prognostic biomarkers.
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Affiliation(s)
- An-Bo Fu
- Institute of Pharmacology and Toxicology, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
- Institute of Gastroenterology, Zhejiang University, Hangzhou, 310002, China
- Department of Gastroenterology, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, 310002, China
| | - Sen-Feng Xiang
- Institute of Pharmacology and Toxicology, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
| | - Qiao-Jun He
- Institute of Pharmacology and Toxicology, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
- Cancer Center, Zhejiang University, Hangzhou, 310058, China.
| | - Mei-Dan Ying
- Institute of Pharmacology and Toxicology, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China.
- Cancer Center, Zhejiang University, Hangzhou, 310058, China.
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Transcription factor ZEB1 regulates PLK1-mediated SKA3 phosphorylation to promote lung cancer cell proliferation, migration and cell cycle. Anticancer Drugs 2022:00001813-990000000-00152. [PMID: 36728910 DOI: 10.1097/cad.0000000000001477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Lung cancer (LC) is one of the most common malignancies worldwide with low 5-year survival rate. The mechanism of spindle and kinetochore-associated complex subunit 3 (SKA3) in LC tumorgenesis remains largely unclear. The expression of SKA3 in LC cells was detected by quantitative PCR. Cell proliferation, migration and cell cycle were evaluated by functional assays including 5-ethynyl-2'-deoxyuridine, wound healing, transwell assays and flow cytometry analysis. Bioinformatics analysis, chromatin immunoprecipitation, luciferase reporter, co-immunoprecipitation and in vitro phosphorylation assays were applied to explore the interactions between zinc finger E-box binding homeobox 1 (ZEB1) and SKA3/polo-like kinase 1 (PLK1). SKA3 is highly expressed in LC cell lines and drives LC cell proliferation, migration and cell cycle. PLK1 also enhances the malignancy of LC cells. PLK1 can mediate SKA3 phosphorylation and enhance the stability of SKA3 protein, thus promoting LC progression. Besides, we found that transcription factor ZEB1 transcriptionally activates SKA3/PLK1 expression, contributing to LC cell malignancy. This study demonstrated that transcription factor ZEB1 modulates PLK1-mediated SKA3 phosphorylation to accelerate LC cell growth, migration and cycle, which might offer novel insight into LC treatment.
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Single-cell transcriptomics reveals the role of Macrophage-Naïve CD4 + T cell interaction in the immunosuppressive microenvironment of primary liver carcinoma. J Transl Med 2022; 20:466. [PMID: 36221095 PMCID: PMC9552358 DOI: 10.1186/s12967-022-03675-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 09/28/2022] [Indexed: 11/30/2022] Open
Abstract
Background Liver carcinoma generally presents as an immunosuppressive microenvironment that promotes tumor evasion. The intercellular crosstalk of immune cells significantly influences the construction of an immunosuppressive microenvironment. This study aimed to investigate the important interactions between immune cells and their targeting drugs in liver carcinoma, by using single-cell and bulk transcriptomic data. Methods Single-cell and bulk transcriptomic data were retrieved from Gene Expression Omnibus (GSE159977, GSE136103, and GSE125449) and The Cancer Genome Atlas (TGCA-LIHC), respectively. Quality control, dimension reduction, clustering, and annotation were performed according to the Scanpy workflow based on Python. Cell–cell interactions were explored using the CellPhone database and CellChat. Trajectory analysis was executed using a partition-based graph abstraction method. The transcriptomic factors (TFs) were predicted using single-cell regulatory network inference and clustering (SCENIC). The target genes from TFs were used to establish a related score based on the TCGA cohort; this score was subsequently validated by survival, gene set enrichment, and immune cell infiltration analyses. Drug prediction was performed based on the Cancer Therapeutics Response Portal and PRISM Repurposing datasets. Results Thirty-one patients at four different states, including health, hepatitis, cirrhosis, and cancer, were enrolled in this study. After dimension reduction and clustering, twenty-two clusters were identified. Cell–cell interaction analyses indicated that macrophage-naive CD4 + T cell interaction significantly affect cancerous state. In brief, macrophages interact with naive CD4 + T cells via different pathways in different states. The results of SCENIC indicated that macrophages present in cancer cells were similar to those present during cirrhosis. A macrophage-naive CD4 + T cell (MNT) score was generated by the SCENIC-derived target genes. Based on the MNT score, five relevant drugs (inhibitor of polo-like kinase 1, inhibitor of kinesin family member 11, dabrafenib, ispinesib, and epothilone-b) were predicted. Conclusions This study reveals the crucial role of macrophage-naive CD4 + T cell interaction in the immunosuppressive microenvironment of liver carcinoma. Tumor-associated macrophages may be derived from cirrhosis and can initiate liver carcinoma. Predictive drugs that target the macrophage-naive CD4 + T cell interaction may help to improve the immunosuppressive microenvironment and prevent immune evasion. The relevant mechanisms need to be further validated in experiments and cohort studies. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12967-022-03675-2.
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Ju G, Zhou T, Zhang R, Pan X, Xue B, Miao S. DUSP12 regulates the tumorigenesis and prognosis of hepatocellular carcinoma. PeerJ 2021; 9:e11929. [PMID: 34414037 PMCID: PMC8344690 DOI: 10.7717/peerj.11929] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/18/2021] [Indexed: 01/20/2023] Open
Abstract
Background Dual specificity protein phosphatase (DUSP)12 is an atypical member of the protein tyrosine phosphatase family, which are overexpressed in multiple types of malignant tumors. This protein family protect cells from apoptosis and promotes the proliferation and motility of cells. However, the pathological role of DUSP12 in hepatocellular carcinoma (HCC) is incompletely understood. Methods We analyzed mRNA expression of DUSP12 between HCC and normal liver tissues using multiple online databases, and explored the status of DUSP12 mutants using the cBioPortal database. The correlation between DUSP12 expression and tumor-infiltrating immune cells was demonstrated using the Tumor Immune Estimation Resource database and the Tumor and Immune System Interaction Database. Loss of function assay was utilized to evaluate the role of DUSP12 in HCC progression. Results DUSP12 had higher expression along with mRNA amplification in HCC tissues compared with those in normal liver tissues, which suggested that higher DUSP12 expression predicted shorter overall survival. Analyses of functional enrichment of differentially expressed genes suggested that DUSP12 regulated HCC tumorigenesis, and that knockdown of DUSP12 expression by short hairpin (sh)RNA decreased the proliferation and migration of HCC cells. Besides, DUSP12 expression was positively associated with the infiltration of cluster of differentiation (CD)4+ T cells (especially CD4+ regulatory T cells), macrophages, neutrophils and dendritic cells. DUSP12 expression was positively associated with immune-checkpoint moieties, and was downregulated in a C3 immune-subgroup of HCC (which had the longest survival). Conclusion These data suggest that DUSP12 may have a critical role in the tumorigenesis, infiltration of immune cells, and prognosis of HCC.
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Affiliation(s)
- Gaoda Ju
- Department of Medical Oncology, Beijing Cancer Hospital, Peking University, Beijing, China
| | - Tianhao Zhou
- Shanghai First People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Rui Zhang
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Xiaozao Pan
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Bing Xue
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining, China
| | - Sen Miao
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining, China
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5
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Pokorná Z, Vysloužil J, Hrabal V, Vojtěšek B, Coates PJ. The foggy world(s) of p63 isoform regulation in normal cells and cancer. J Pathol 2021; 254:454-473. [PMID: 33638205 DOI: 10.1002/path.5656] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/10/2021] [Accepted: 02/24/2021] [Indexed: 12/19/2022]
Abstract
The p53 family member p63 exists as two major protein variants (TAp63 and ΔNp63) with distinct expression patterns and functional properties. Whilst downstream target genes of p63 have been studied intensively, how p63 variants are themselves controlled has been relatively neglected. Here, we review advances in understanding ΔNp63 and TAp63 regulation, highlighting their distinct pathways. TAp63 has roles in senescence and metabolism, and in germ cell genome maintenance, where it is activated post-transcriptionally by phosphorylation cascades after DNA damage. The function and regulation of TAp63 in mesenchymal and haematopoietic cells is less clear but may involve epigenetic control through DNA methylation. ΔNp63 functions to maintain stem/progenitor cells in various epithelia and is overexpressed in squamous and certain other cancers. ΔNp63 is transcriptionally regulated through multiple enhancers in concert with chromatin modifying proteins. Many signalling pathways including growth factors, morphogens, inflammation, and the extracellular matrix influence ΔNp63 levels, with inconsistent results reported. There is also evidence for reciprocal regulation, including ΔNp63 activating its own transcription. ΔNp63 is downregulated during cell differentiation through transcriptional regulation, while post-transcriptional events cause proteasomal degradation. Throughout the review, we identify knowledge gaps and highlight discordances, providing potential explanations including cell-context and cell-matrix interactions. Identifying individual p63 variants has roles in differential diagnosis and prognosis, and understanding their regulation suggests clinically approved agents for targeting p63 that may be useful combination therapies for selected cancer patients. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Zuzana Pokorná
- Research Centre of Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, Brno, Czech Republic
| | - Jan Vysloužil
- Research Centre of Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, Brno, Czech Republic
| | - Václav Hrabal
- Research Centre of Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, Brno, Czech Republic.,Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Borˇivoj Vojtěšek
- Research Centre of Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, Brno, Czech Republic
| | - Philip J Coates
- Research Centre of Applied Molecular Oncology (RECAMO), Masaryk Memorial Cancer Institute, Brno, Czech Republic
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6
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Armstrong SR, Wu H, Wang B, Abuetabh Y, Sergi C, Leng RP. The Regulation of Tumor Suppressor p63 by the Ubiquitin-Proteasome System. Int J Mol Sci 2016; 17:ijms17122041. [PMID: 27929429 PMCID: PMC5187841 DOI: 10.3390/ijms17122041] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 11/23/2016] [Accepted: 11/30/2016] [Indexed: 12/18/2022] Open
Abstract
The protein p63 has been identified as a homolog of the tumor suppressor protein p53 and is capable of inducing apoptosis, cell cycle arrest, or senescence. p63 has at least six isoforms, which can be divided into two major groups: the TAp63 variants that contain the N-terminal transactivation domain and the ΔNp63 variants that lack the N-terminal transactivation domain. The TAp63 variants are generally considered to be tumor suppressors involved in activating apoptosis and suppressing metastasis. ΔNp63 variants cannot induce apoptosis but can act as dominant negative inhibitors to block the function of TAp53, TAp73, and TAp63. p63 is rarely mutated in human tumors and is predominately regulated at the post-translational level by phosphorylation and ubiquitination. This review focuses primarily on regulation of p63 by the ubiquitin E-3 ligase family of enzymes via ubiquitination and proteasome-mediated degradation, and introduces a new key regulator of the p63 protein.
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Affiliation(s)
- Stephen R Armstrong
- 370 Heritage Medical Research Center, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
| | - Hong Wu
- 370 Heritage Medical Research Center, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
| | - Benfan Wang
- 370 Heritage Medical Research Center, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
| | - Yasser Abuetabh
- 370 Heritage Medical Research Center, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
| | - Consolato Sergi
- Department of Laboratory Medicine and Pathology (5B4. 09), University of Alberta, Edmonton, AB T6G 2B7, Canada.
| | - Roger P Leng
- 370 Heritage Medical Research Center, Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2S2, Canada.
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Posch C, Cholewa BD, Vujic I, Sanlorenzo M, Ma J, Kim ST, Kleffel S, Schatton T, Rappersberger K, Gutteridge R, Ahmad N, Ortiz/Urda S. Combined Inhibition of MEK and Plk1 Has Synergistic Antitumor Activity in NRAS Mutant Melanoma. J Invest Dermatol 2015; 135:2475-2483. [PMID: 26016894 PMCID: PMC4567913 DOI: 10.1038/jid.2015.198] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 05/08/2015] [Accepted: 05/18/2015] [Indexed: 02/08/2023]
Abstract
About one-third of cancers harbor activating mutations in rat sarcoma viral oncogene homolog (RAS) oncogenes. In melanoma, aberrant neuroblastoma-RAS (NRAS) signaling fuels tumor progression in about 20% of patients. Current therapeutics for NRAS-driven malignancies barely affect overall survival. To date, pathway interference downstream of mutant NRAS seems to be the most promising approach. In this study, data revealed that mutant NRAS induced Polo-like kinase 1 (Plk1) expression, and pharmacologic inhibition of Plk1 stabilized the size of NRAS mutant melanoma xenografts. The combination of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK) and Plk1 inhibitors resulted in a significant growth reduction of NRAS mutant melanoma cells in vitro, and regression of xenografted NRAS mutant melanoma in vivo. Independent cell cycle arrest and increased induction of apoptosis underlies the synergistic effect of this combination. Data further suggest that the p53 signaling pathway is of key importance to the observed therapeutic efficacy. This study provides in vitro, in vivo, and first mechanistic data that an MEK/Plk1 inhibitor combination might be a promising treatment approach for patients with NRAS-driven melanoma. As mutant NRAS signaling is similar across different malignancies, this inhibitor combination could also offer a previously unreported treatment modality for NRAS mutant tumors of other cell origins.
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Affiliation(s)
- C Posch
- University of California San Francisco, Department of Dermatology, Mt. Zion Cancer Research Center, 2340 Sutter Street N461, 94115 San Francisco – USA
- Brigham and Women's Hospital, Harvard Medical School, Department of Dermatology, 77 Avenue Louis Pasteur, 02115 Boston – USA
- The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Department of Dermatology, Juchgasse 25, 1030 Vienna – Austria
| | - BD Cholewa
- University of Wisconsin, Department of Dermatology, 7418 Wisconsin Institutes for Medical Research, 1111 Highland Ave, Madison, WI 53705 – USA
| | - I Vujic
- University of California San Francisco, Department of Dermatology, Mt. Zion Cancer Research Center, 2340 Sutter Street N461, 94115 San Francisco – USA
- The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Department of Dermatology, Juchgasse 25, 1030 Vienna – Austria
| | - M Sanlorenzo
- University of California San Francisco, Department of Dermatology, Mt. Zion Cancer Research Center, 2340 Sutter Street N461, 94115 San Francisco – USA
- Department of Medical Sciences, Section of Dermatology, University of Turin – Italy
| | - J Ma
- University of California San Francisco, Department of Dermatology, Mt. Zion Cancer Research Center, 2340 Sutter Street N461, 94115 San Francisco – USA
| | - ST Kim
- University of California San Francisco, Department of Dermatology, Mt. Zion Cancer Research Center, 2340 Sutter Street N461, 94115 San Francisco – USA
| | - S Kleffel
- Brigham and Women's Hospital, Harvard Medical School, Department of Dermatology, 77 Avenue Louis Pasteur, 02115 Boston – USA
| | - T Schatton
- Brigham and Women's Hospital, Harvard Medical School, Department of Dermatology, 77 Avenue Louis Pasteur, 02115 Boston – USA
| | - K Rappersberger
- The Rudolfstiftung Hospital, Academic Teaching Hospital, Medical University Vienna, Department of Dermatology, Juchgasse 25, 1030 Vienna – Austria
| | - R Gutteridge
- University of Wisconsin, Department of Dermatology, 7418 Wisconsin Institutes for Medical Research, 1111 Highland Ave, Madison, WI 53705 – USA
| | - N Ahmad
- University of Wisconsin, Department of Dermatology, 7418 Wisconsin Institutes for Medical Research, 1111 Highland Ave, Madison, WI 53705 – USA
| | - S Ortiz/Urda
- University of California San Francisco, Department of Dermatology, Mt. Zion Cancer Research Center, 2340 Sutter Street N461, 94115 San Francisco – USA
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8
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Li D, Li C, Wu M, Chen Q, Wang Q, Ren J, Zhang Y. PKCδ stabilizes TAp63 to promote cell apoptosis. FEBS Lett 2015; 589:2094-9. [PMID: 26112605 DOI: 10.1016/j.febslet.2015.06.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 06/01/2015] [Accepted: 06/05/2015] [Indexed: 12/25/2022]
Abstract
PKCδ and p63 are respectively reported to play important roles in cell apoptosis. But there is no report on interaction between them in regulation of apoptosis. In the present study, we found that PKCδ can directly associate and up-regulate TA isoforms of p63 (TAp63) proteins via increasing their stability. PKCδ kinase activity and Thr157 site in TAp63 are crucial for this PKCδ-induced accumulation of TAp63. PKCδ can also enhance TAp63-mediated transcription and cell apoptosis. Taken together, our data indicate that PKCδ phosphorylates TAp63 proteins at Thr157 to stabilize them and promote cell apoptosis.
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Affiliation(s)
- Decai Li
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China
| | - Chenghua Li
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China
| | - Min Wu
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China
| | - Qiongqiong Chen
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China
| | - Qiao Wang
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China
| | - Jian Ren
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China
| | - Yujun Zhang
- Center of Growth, Metabolism and Aging, Key Laboratory of Biological Resources and Ecological Environment of Ministry of Education, College of Life Sciences, Chengdu 610065, China.
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9
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Receptor-type protein tyrosine phosphatase κ directly dephosphorylates CD133 and regulates downstream AKT activation. Oncogene 2014; 34:1949-60. [PMID: 24882578 DOI: 10.1038/onc.2014.141] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 04/02/2014] [Accepted: 04/10/2014] [Indexed: 12/21/2022]
Abstract
Although CD133 has been considered to be a molecular marker for cancer stem cells, its functional roles in tumorigenesis remain unclear. We here examined the molecular basis behind CD133-mediated signaling. Knockdown of CD133 resulted in the retardation of xenograft tumor growth of colon cancer-derived HT-29 and LoVo cells accompanied by hypophosphorylation of AKT, which diminished β-catenin/T-cell factor-mediated CD44 expression. As tyrosine residues of CD133 at positions 828 and 852 were phosphorylated in HT-29 and SW480 cells, we further addressed the significance of this phosphorylation in the tumorigenesis of SW480 cells expressing mutant CD133, with substitution of these tyrosine residues by glutamate (CD133-EE) or phenylalanine (CD133-FF). Forced expression of CD133-EE promoted much more aggressive xenograft tumor growth relative to wild-type CD133-expressing cells accompanied by hyperphosphorylation of AKT; however, CD133-FF expression had negligible effects on AKT phosphorylation and xenograft tumor formation. Intriguingly, the tyrosine phosphorylation status of CD133 was closely linked to the growth of SW480-derived spheroids. Using yeast two-hybrid screening, we finally identified receptor-type protein tyrosine phosphatase κ (PTPRK) as a binding partner of CD133. In vitro studies demonstrated that PTPRK associates with the carboxyl-terminal region of CD133 through its intracellular phosphatase domains and also catalyzes dephosphorylation of CD133 at tyrosine-828/tyrosine-852. Silencing of PTPRK elevated the tyrosine phosphorylation of CD133, whereas forced expression of PTPRK reduced its phosphorylation level markedly and abrogated CD133-mediated AKT phosphorylation. Endogenous CD133 expression was also closely associated with higher AKT phosphorylation in primary colon cancer cells, and ectopic expression of CD133 enhanced AKT phosphorylation. Furthermore, lower PTPRK expression significantly correlated with the poor prognosis of colon cancer patients with high expression of CD133. Thus, our present findings strongly indicate that the tyrosine phosphorylation of CD133, which is dephosphorylated by PTPRK, regulates AKT signaling and has a critical role in colon cancer progression.
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10
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Regulation of p63 protein stability via ubiquitin-proteasome pathway. BIOMED RESEARCH INTERNATIONAL 2014; 2014:175721. [PMID: 24822180 PMCID: PMC4009111 DOI: 10.1155/2014/175721] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2013] [Revised: 03/10/2014] [Accepted: 03/28/2014] [Indexed: 11/20/2022]
Abstract
The p53-related p63 gene encodes multiple protein isoforms, which are involved in a variety of biological activities. p63 protein stability is mainly regulated by the ubiquitin-dependent proteasomal degradation pathway. Several ubiquitin E3 ligases have been identified and some protein kinases as well as other kinds of proteins are involved in regulation of p63 protein stability. These regulators are responsive to diverse extracellular signaling, resulting in changes of the p63 protein levels and impacting different biological processes.
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11
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Abstract
Polo-like kinase 1 (Plk1) is a well-established mitotic regulator with a diverse range of biologic functions continually being identified throughout the cell cycle. Preclinical evidence suggests that the molecular targeting of Plk1 could be an effective therapeutic strategy in a wide range of cancers; however, that success has yet to be translated to the clinical level. The lack of clinical success has raised the question of whether there is a true oncogenic addiction to Plk1 or if its overexpression in tumors is solely an artifact of increased cellular proliferation. In this review, we address the role of Plk1 in carcinogenesis by discussing the cell cycle and DNA damage response with respect to their associations with classic oncogenic and tumor suppressor pathways that contribute to the transcriptional regulation of Plk1. A thorough examination of the available literature suggests that Plk1 activity can be dysregulated through key transformative pathways, including both p53 and pRb. On the basis of the available literature, it may be somewhat premature to draw a definitive conclusion on the role of Plk1 in carcinogenesis. However, evidence supports the notion that oncogene dependence on Plk1 is not a late occurrence in carcinogenesis and it is likely that Plk1 plays an active role in carcinogenic transformation.
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Affiliation(s)
- Brian D. Cholewa
- Department of Dermatology, University of Wisconsin, Madison, WI
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI
| | - Xiaoqi Liu
- Department of Biochemistry, Purdue University, West Lafayette, IN
| | - Nihal Ahmad
- Department of Dermatology, University of Wisconsin, Madison, WI
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, WI
- William S. Middleton Memorial VA Hospital, Madison, WI
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12
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Humphries LA, Godbersen JC, Danilova OV, Kaur P, Christensen BC, Danilov AV. Pro-apoptotic TP53 homolog TAp63 is repressed via epigenetic silencing and B-cell receptor signalling in chronic lymphocytic leukaemia. Br J Haematol 2013; 163:590-602. [PMID: 24117128 DOI: 10.1111/bjh.12580] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 08/21/2013] [Indexed: 02/05/2023]
Abstract
Chronic lymphocytic leukaemia (CLL) is an accumulative disorder marked by deficient apoptosis. The TP53 homolog TAp63 promotes apoptosis and chemosensitivity in solid tumours and its deregulation may contribute to CLL cell survival. We found that TAp63α was the most prevalent TP63 isoform in CLL. Compared to healthy B cells, TAp63 mRNA was repressed in 55·7% of CLL samples. TP63 promoter methylation was high in CLL and inversely correlated with TP63 protein expression in B-cell lymphoma cell lines. siRNA-mediated knockdown of TP63 resulted in partial protection from spontaneous apoptosis accompanied by reductions in PMAIP1 (NOXA), BBC3 (PUMA), and BAX mRNA in CLL cells and increased proliferation of Raji lymphoma cells. TAp63 mRNA levels were higher in CLL with unmutated IGHV. B-cell receptor (BCR) engagement led to repression of TP63 mRNA expression in malignant B cells, while pharmacological inhibition of BCR signalling prevented TP63 downregulation. MIR21, known to target TAp63, correlated inversely with TAp63 expression in CLL, and BCR-mediated downregulation of TP63 was accompanied by MIR21 upregulation in most CLL samples. Our data illustrate the pro-apoptotic function of TP63, provide insights into the mechanisms of BCR-targeting agents, and establish a rationale for designing novel approaches to induce TP63 in CLL and B-cell lymphoma.
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Louwen F, Yuan J. Battle of the eternal rivals: restoring functional p53 and inhibiting Polo-like kinase 1 as cancer therapy. Oncotarget 2013; 4:958-71. [PMID: 23948487 PMCID: PMC3759674 DOI: 10.18632/oncotarget.1096] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 07/11/2013] [Indexed: 01/09/2023] Open
Abstract
Polo-like kinase 1, a pivotal regulator of mitosis and cytokinesis, is highly expressed in a broad spectrum of tumors and its expression correlates often with poor prognosis, suggesting its potential as a therapeutic target. p53, the guardian of the genome, is the most important tumor suppressor. In this review, we address the intertwined relationship of these two key molecules by fighting each other as eternal rivals in many signaling pathways. p53 represses the promoter of Polo-like kinase 1, whereas Polo-like kinase 1 inhibits p53 and its family members p63 and p73 in cancer cells lacking functional p53. Plk1 inhibitors target all rapidly dividing cells irrespective of tumor cells or non-transformed normal but proliferating cells. Upon treatment with Plk1 inhibitors, p53 in tumor cells is activated and induces strong apoptosis, whereas tumor cells with inactive p53 arrest in mitosis with DNA damage. Thus, inactive p53 is not associated with a susceptible cytotoxicity of Polo-like kinase 1 inhibition and could rather foster the induction of polyploidy/aneuploidy in surviving cells. In addition, compared to the mono-treatment, combination of Polo-like kinase 1 inhibition with anti-mitotic or DNA damaging agents boosts more severe mitotic defects, effectually triggers apoptosis and strongly inhibits proliferation of cancer cells with functional p53. In this regard, restoration of p53 in tumor cells with loss or mutation of p53 will reinforce the cytotoxicity of combined Polo-like kinase 1 therapy and provide a proficient strategy for combating relapse and metastasis of cancer.
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Affiliation(s)
- Frank Louwen
- Department of Gynecology and Obstetrics, School of Medicine, J. W. Goethe-University, Frankfurt, Germany
| | - Juping Yuan
- Department of Gynecology and Obstetrics, School of Medicine, J. W. Goethe-University, Frankfurt, Germany
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14
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Wierer M, Verde G, Pisano P, Molina H, Font-Mateu J, Di Croce L, Beato M. PLK1 signaling in breast cancer cells cooperates with estrogen receptor-dependent gene transcription. Cell Rep 2013; 3:2021-32. [PMID: 23770244 DOI: 10.1016/j.celrep.2013.05.024] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2012] [Revised: 04/04/2013] [Accepted: 05/13/2013] [Indexed: 11/23/2022] Open
Abstract
Polo-like kinase 1 (PLK1) is a key regulator of cell division and is overexpressed in many types of human cancers. Compared to its well-characterized role in mitosis, little is known about PLK1 functions in interphase. Here, we report that PLK1 mediates estrogen receptor (ER)-regulated gene transcription in human breast cancer cells. PLK1 interacts with ER and is recruited to ER cis-elements on chromatin. PLK1-coactivated genes included classical ER target genes such as Ps2, Wisp2, and Serpina3 and were enriched in developmental and tumor-suppressive functions. Performing large-scale phosphoproteomics of estradiol-treated MCF7 cells in the presence or absence of the specific PLK1 inhibitor BI2536, we identified several PLK1 end targets involved in transcription, including the histone H3K4 trimethylase MLL2, the function of which on ER target genes was impaired by PLK1 inhibition. Our results propose a mechanism for the tumor-suppressive role of PLK1 in mammals as an interphase transcriptional regulator.
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Affiliation(s)
- Michael Wierer
- Gene Regulation Stem Cells and Cancer Program, Center for Genomic Regulation (CRG), Dr. Aiguader 88, 08003 Barcelona, Spain
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15
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Lu D, Han C, Wu T. 15-hydroxyprostaglandin dehydrogenase-derived 15-keto-prostaglandin E2 inhibits cholangiocarcinoma cell growth through interaction with peroxisome proliferator-activated receptor-γ, SMAD2/3, and TAP63 proteins. J Biol Chem 2013; 288:19484-502. [PMID: 23687300 DOI: 10.1074/jbc.m113.453886] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Prostaglandin E2 (PGE2) is a potent lipid mediator that plays a key role in inflammation and carcinogenesis. NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) catalyzes the oxidation of the 15(S)-hydroxyl group of PGE2, which leads to PGE2 biotransformation. In this study, we showed that the 15-PGDH-derived 15-keto-PGE2 is an endogenous peroxisome proliferator-activated receptor-γ (PPAR-γ) ligand that causes PPAR-γ dissociation from Smad2/3, allowing Smad2/3 association with the TGF-β receptor I and Smad anchor for receptor activation and subsequent Smad2/3 phosphorylation and transcription activation in human cholangiocarcinoma cells. The 15-PGDH/15-keto-PGE2-induced Smad2/3 phosphorylation resulted in the formation of the pSmad2/3-TAP63-p53 ternary complex and their binding to the TAP63 promoter, inducing TAP63 autotranscription. The role of TAP63 in 15-PGDH/15-keto-PGE2-induced inhibition of tumor growth was further supported by the observation that knockdown of TAP63 prevented 15-PGDH-induced inhibition of tumor cell proliferation, colony formation, and migration. These findings disclose a novel 15-PGDH-mediated 15-keto-PGE2 signaling cascade that interacts with PPAR-γ, Smad2/3, and TAP63.
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Affiliation(s)
- Dongdong Lu
- Department of Pathology and Laboratory Medicine, Tulane University School of Medicine, New Orleans, Louisiana 70112, USA
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16
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Cherukuri P, DeCastro AJ, Balboni AL, Downey SL, Liu JY, Hutchinson JA, DiRenzo J. Phosphorylation of ΔNp63α via a novel TGFβ/ALK5 signaling mechanism mediates the anti-clonogenic effects of TGFβ. PLoS One 2012; 7:e50066. [PMID: 23166821 PMCID: PMC3500343 DOI: 10.1371/journal.pone.0050066] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 10/19/2012] [Indexed: 01/03/2023] Open
Abstract
Genetic analysis of TP63 implicates ΔNp63 isoforms in preservation of replicative capacity and cellular lifespan within adult stem cells. ΔNp63α is also an oncogene and survival factor that mediates therapeutic resistance in squamous carcinomas. These diverse activities are the result of genetic and functional interactions between TP63 and an array of morphogenic and morphostatic signals that govern tissue and tumor stasis, mitotic polarity, and cell fate; however the cellular signals that account for specific functions of TP63 are incompletely understood. To address this we sought to identify signaling pathways that regulate expression, stability or activity of ΔNp63α. An siRNA-based screen of the human kinome identified the Type 1 TGFβ receptor, ALK5, as the kinase required for phosphorylation of ΔNp63α at Serine 66/68 (S66/68). This activity is TGFβ-dependent and sensitive to either ALK5-directed siRNA or the ALK5 kinase inhibitor A83-01. Mechanistic studies support a model in which ALK5 is proteolytically cleaved at the internal juxtamembrane region resulting in the translocation of the C-terminal ALK5-intracellular kinase domain (ALK5IKD). In this study, we demonstrate that ALK5-mediated phosphorylation of ΔNp63α is required for the anti-clonogenic effects of TGFΒ and ectopic expression of ALK5IKD mimics these effects. Finally, we present evidence that ultraviolet irradiation-mediated phosphorylation of ΔNp63α is sensitive to ALK5 inhibitors. These findings identify a non-canonical TGFβ-signaling pathway that mediates the anti-clonogenic effects of TGFβ and the effects of cellular stress via ΔNp63α phosphorylation.
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Affiliation(s)
- Pratima Cherukuri
- Department of Pharmacology and Toxicology, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Andrew J. DeCastro
- Department of Pharmacology and Toxicology, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Program in Experimental Molecular Medicine, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Amanda L. Balboni
- Department of Pharmacology and Toxicology, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Program in Experimental Molecular Medicine, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Sondra L. Downey
- Department of Pharmacology and Toxicology, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Program in Experimental Molecular Medicine, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Jennifer Y. Liu
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, United States of America
| | - Justine A. Hutchinson
- Department of Pharmacology and Toxicology, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Program in Experimental Molecular Medicine, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - James DiRenzo
- Department of Pharmacology and Toxicology, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- Program in Experimental Molecular Medicine, The Audrey and Theodor Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
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17
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Xu WJ, Zhang S, Yang Y, Zhang N, Wang W, Liu SY, Tian HW, Dai L, Xie Q, Zhao X, Wei YQ, Deng HX. Efficient inhibition of human colorectal carcinoma growth by RNA interference targeting polo-like kinase 1 in vitro and in vivo. Cancer Biother Radiopharm 2011; 26:427-36. [PMID: 21797676 DOI: 10.1089/cbr.2010.0922] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Polo-like kinase 1 (PLK1) showing a high expression in various kinds of tumors is considered a candidate target for cancer therapy. The aim of our study was to explore the effects of silencing PLK1 gene on human colorectal carcinoma cell line HCT-116 in vitro and in vivo. In vitro, the plasmids generating short hairpin RNA (shRNA)-targeting PLK1 were transfected into HCT-116 by using FugeneHD reagent, and the silencing potency was measured by RT-PCR, western blot, flow cytometry, and Caspase-Glo 3/7 assay, respectively. In vivo, the growth inhibition capacity of PLK1-shRNA on HCT-116 xenograft was measured in nude mice. Then, the silencing effect of PLK1 was analyzed by RT-PCR, western blot, and immunohistochemistry, respectively. Apoptosis, angiogenesis, and proliferation in tumor tissues were measured by TUNEL, CD31, and PCNA stain, respectively. The RNA interference targeting PLK1 significantly decreased the expression of PLK1 in vitro. More importantly, anti-PLK1 treatment in HCT-116 xenograft decreased tumor weight by 81.58% compared with the control group (p<0.001), accompanied with decreased PLK1 mRNA and protein expression, increased cell apoptosis, and reduced angiogenesis and proliferation (p<0.001). Our study showed that knockdown of PLK1 by shRNA might be the potential therapeutic approach against human colorectal carcinoma.
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Affiliation(s)
- Wen-Jing Xu
- State Key Laboratory of Biotherapy, West China Hospital and West China Medical School, Sichuan University, Ke-yuan Road 4, No. 1 Gao-peng Street, Chengdu, Sichuan, The People's Republic of China
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18
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Ozaki T, Kubo N, Nakagawara A. p73-Binding Partners and Their Functional Significance. INTERNATIONAL JOURNAL OF PROTEOMICS 2011; 2010:283863. [PMID: 22084676 PMCID: PMC3195385 DOI: 10.1155/2010/283863] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 10/26/2010] [Indexed: 12/21/2022]
Abstract
p73 is one of the tumor-suppressor p53 family of nuclear transcription factor. As expected from the structural similarity between p53 and p73, p73 has a tumor-suppressive function. However, p73 was rarely mutated in human primary tumors. Under normal physiological conditions, p73 is kept at an extremely low level to allow cells normal growth. In response to a certain subset of DNA damages, p73 is induced dramatically and transactivates an overlapping set of p53-target genes implicated in the promotion of cell cycle arrest and/or apoptotic cell death. Cells undergo cell cycle arrest and/or apoptotic cell death depending on the type and strength of DNA damages. p73 is regulated largely through the posttranslational modifications such as phosphorylation and acetylation. These chemical modifications are tightly linked to direct protein-protein interactions. In the present paper, the authors describe the functional significance of the protein-protein interactions in the regulation of proapoptotic p73.
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Affiliation(s)
- Toshinori Ozaki
- Laboratory of Anti-tumor Research, Chiba Cancer Center Research Institute, Chiba 260-8717, Japan
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19
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Ozaki T, Nakagawara A. p53: the attractive tumor suppressor in the cancer research field. J Biomed Biotechnol 2010; 2011:603925. [PMID: 21188172 PMCID: PMC3004423 DOI: 10.1155/2011/603925] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 10/07/2010] [Indexed: 01/16/2023] Open
Abstract
p53 is one of the most studied tumor suppressors in the cancer research field. Of note, over 50% of human tumors carry loss of function mutations, and thus p53 has been considered to be a classical Knudson-type tumor suppressor. From the functional point of view, p53 is a nuclear transcription factor to transactivate a variety of its target genes implicated in the induction of cell cycle arrest, DNA repair, and apoptotic cell death. In response to cellular stresses such as DNA damage, p53 is activated and promotes cell cycle arrest followed by the replacement of DNA lesions and/or apoptotic cell death. Therefore, p53 is able to maintain the genomic integrity to prevent the accumulation of genetic alterations, and thus stands at a crossroad between cell survival and cell death. In this paper, we describe a variety of molecular mechanisms behind the regulation of p53.
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Affiliation(s)
- Toshinori Ozaki
- Laboratory of Anti-Tumor Research, Chiba Cancer Center Research Institute, Chiba 260-8717, Japan
| | - Akira Nakagawara
- Laboratory of Innovative Cancer Therapeutics, Chiba Cancer Center Research Institute, 666-2 Nitona, Chuoh-ku, Chiba 260-8717, Japan
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20
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Yao JY, Pao CC, Chen JK. Transcriptional activity of TAp63 promoter is regulated by c-jun. J Cell Physiol 2010; 225:898-904. [PMID: 20607803 DOI: 10.1002/jcp.22300] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The transcription factor p63 belongs to the p53 protein family and plays an important role in epithelial development. Recent studies showed that p63 is over-expressed in some human squamous cell carcinomas of the head and neck, suggesting a role in carcinogenesis. The p63 gene contains two promoters and alternative promoter usage generates two groups of proteins with (TAp63) or without (ΔNp63) the transactivation domain. Although the roles of TAp63 in epithelial development have been described in numerous recent studies, the regulation of its expression has not been elucidated. In this study, we showed that the transcriptional activity of the TAp63 promoter and TAp63 protein level were both up-regulated by an increased c-jun activity in Hep3B human hepatocellular carcinoma cell. Moreover, the elevated TAp63 expression was coincided with an increased binding of c-jun to the TAp63 promoter. Point mutation of the sp1 binding site within the TAp63 promoter region attenuated the effect of c-jun on TAp63 expression. Knockdown of TAp63 expression by shRNA led to increased proliferation of Hep3B cell compared to that of the mock cell, suggesting a growth suppressive effect of TAp63.
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Affiliation(s)
- Jeng-Yuan Yao
- Department of Physiology, College of medicine, Chang Gung University, Kweishan, Taoyuan, Taiwan
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21
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Shi Y, Takenobu H, Kurata K, Yamaguchi Y, Yanagisawa R, Ohira M, Koike K, Nakagawara A, Jiang LL, Kamijo T. HDM2 impairs Noxa transcription and affects apoptotic cell death in a p53/p73-dependent manner in neuroblastoma. Eur J Cancer 2010; 46:2324-34. [PMID: 20591651 DOI: 10.1016/j.ejca.2010.05.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 05/17/2010] [Accepted: 05/24/2010] [Indexed: 11/20/2022]
Abstract
HDM2, a human homologue of MDM2, is a major negative regulator of p53 function, and increased expression of HDM2 by its promoter polymorphism SNP309 resulted in p53 inactivation and an increased risk of several tumours, including neuroblastoma (NB). Herein, we show that increased expression of HDM2 is related to a worse prognosis in MYCN-amplified NB patients. HDM2 plays an important role in the expression of Noxa, a pro-apoptotic molecule of the Bcl-2 family, which induces NB cell apoptotic death after doxorubcin (Doxo) treatment. Knockdown of HDM2 by siRNA resulted in the upregulation of Noxa at mRNA/protein levels and improved the sensitivity of Doxo-resistant NB cells, although these were not observed in p53-mutant NB cells. Noxa-knockdown abolished the recovered Doxo-induced cell death by HDM2 reduction. Intriguingly, resistance to Doxo was up-regulated by over-expression of HDM2 in Doxo-sensitive NB cells. By HDM2 expression, p53 was inactivated but its degradation was not accelerated, suggesting that p53 was degraded in a proteasome-independent manner in NB cells; downstream effectors of p53, p21(Cip1/Waf1) and Noxa were suppressed by HDM2. Noxa transcription was considerably regulated by both p53 and p73 in NB cells. Furthermore, in vivo binding of p53 and p73 to Noxa promoter was suppressed and Noxa promoter activation was inhibited by HDM2. Taken together, our results may indicate that the HDM2-related resistance to chemotherapeutic drugs of NB is regulated by p53/p73-dependent Noxa expression in NB.
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Affiliation(s)
- Yun Shi
- Division of Biochemistry and Molecular Carcinogenesis, Chiba Cancer Center Research Institute, 666-2 Nitona, Chuoh-ku, Chiba 260-8717, Japan
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22
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Cytokinesis and cancer: Polo loves ROCK'n' Rho(A). J Genet Genomics 2010; 37:159-72. [PMID: 20347825 DOI: 10.1016/s1673-8527(09)60034-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Revised: 02/08/2010] [Accepted: 02/09/2010] [Indexed: 12/11/2022]
Abstract
Cytokinesis is the last step of the M (mitosis) phase, yet it is crucial for the faithful division of one cell into two. Cytokinesis failure is often associated with cancer. Cytokinesis can be morphologically divided into four steps: cleavage furrow initiation, cleavage furrow ingression, midbody formation and abscission. Molecular studies have revealed that RhoA as well as its regulators and effectors are important players to ensure a successful cytokinesis. At the same time, Polo-like kinase 1 (Plk1) is an important kinase that can target many substrates and carry out different functions during mitosis, including cytokinesis. Recent studies are beginning to unveil a closer tie between Plk1 and RhoA networks. More specifically, Plk1 phosphorylates the centralspindlin complex Cyk4 and MKLP1/CHO1, thus recruiting RhoA guanine nucleotide-exchange factor (GEF) Ect2 through its phosphopeptide-binding BRCT domains. Ect2 itself can be phosphorylated by Plk1 in vitro. Plk1 can also phosphorylate another GEF MyoGEF to regulate RhoA activity. Once activated, RhoA-GTP will activate downstream effectors, including ROCK1 and ROCK2. ROCK2 is among the proteins that associate with Plk1 Polo-binding domain (PBD) in a large proteomic screen, and Plk1 can phosphorylate ROCK2 in vitro. We review current understandings of the interplay between Plk1, RhoA proteins and other proteins (e.g., NudC, MKLP2, PRC1, CEP55) involved in cytokinesis, with particular emphasis of its clinical implications in cancer.
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