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Kumar S, Arwind DA, Kumar B H, Pandey S, Nayak R, Vithalkar MP, Kumar N, Pai KSR. Inhibition of STAT3: A promising approach to enhancing the efficacy of chemotherapy in medulloblastoma. Transl Oncol 2024; 46:102023. [PMID: 38852276 PMCID: PMC11220551 DOI: 10.1016/j.tranon.2024.102023] [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: 02/03/2024] [Revised: 05/27/2024] [Accepted: 06/01/2024] [Indexed: 06/11/2024] Open
Abstract
Medulloblastoma is a type of brain cancer that primarily affects children. While chemotherapy has been shown to be effective in treating medulloblastoma, the development of chemotherapy resistance remains a challenge. One potential therapeutic approach is to selectively inhibit the inducible transcription factor called STAT3, which is known to play a crucial role in the survival and growth of tumor cells. The activation of STAT3 has been linked to the growth and progression of various cancers, including medulloblastoma. Inhibition of STAT3 has been shown to sensitize medulloblastoma cells to chemotherapy, leading to improved treatment outcomes. Different approaches to STAT3 inhibition have been developed, including small-molecule inhibitors and RNA interference. Preclinical studies have shown the efficacy of STAT3 inhibitors in medulloblastoma, and clinical trials are currently ongoing to evaluate their safety and effectiveness in patients with various solid tumors, including medulloblastoma. In addition, researchers are also exploring ways to optimize the use of STAT3 inhibitors in combination with chemotherapy and identify biomarkers that can predict treatment that will help to develop personalized treatment strategies. This review highlights the potential of selective inhibition of STAT3 as a novel approach for the treatment of medulloblastoma and suggests that further research into the development of STAT3 inhibitors could lead to improved outcomes for patients with aggressive cancer.
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Affiliation(s)
- Sachindra Kumar
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, India
| | - Dube Aakash Arwind
- Department of Pharmacology and toxicology, National Institute of Pharmaceutical Education and Research, Hajipur, Vaishali-844102, Bihar, India
| | - Harish Kumar B
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, India
| | - Samyak Pandey
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, India
| | - Raksha Nayak
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, India
| | - Megh Pravin Vithalkar
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, India
| | - Nitesh Kumar
- Department of Pharmacology and toxicology, National Institute of Pharmaceutical Education and Research, Hajipur, Vaishali-844102, Bihar, India
| | - K Sreedhara Ranganath Pai
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal 576104, India.
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Adesoye T, Tripathy D, Hunt KK, Keyomarsi K. Exploring Novel Frontiers: Leveraging STAT3 Signaling for Advanced Cancer Therapeutics. Cancers (Basel) 2024; 16:492. [PMID: 38339245 PMCID: PMC10854592 DOI: 10.3390/cancers16030492] [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: 10/18/2023] [Revised: 12/21/2023] [Accepted: 12/25/2023] [Indexed: 02/12/2024] Open
Abstract
Signal Transducer and Activator of Transcription 3 (STAT3) plays a significant role in diverse physiologic processes, including cell proliferation, differentiation, angiogenesis, and survival. STAT3 activation via phosphorylation of tyrosine and serine residues is a complex and tightly regulated process initiated by upstream signaling pathways with ligand binding to receptor and non-receptor-linked kinases. Through downstream deregulation of target genes, aberrations in STAT3 activation are implicated in tumorigenesis, metastasis, and recurrence in multiple cancers. While there have been extensive efforts to develop direct and indirect STAT3 inhibitors using novel drugs as a therapeutic strategy, direct clinical application remains in evolution. In this review, we outline the mechanisms of STAT3 activation, the resulting downstream effects in physiologic and malignant settings, and therapeutic strategies for targeting STAT3. We also summarize the pre-clinical and clinical evidence of novel drug therapies targeting STAT3 and discuss the challenges of establishing their therapeutic efficacy in the current clinical landscape.
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Affiliation(s)
- Taiwo Adesoye
- Department of Breast Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA;
| | - Debasish Tripathy
- Department of Breast Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA;
| | - Kelly K. Hunt
- Department of Breast Surgical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA;
| | - Khandan Keyomarsi
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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3
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Shamir I, Tsarfaty I, Paret G, Nevo-Caspi Y. Differential silencing of STAT3 isoforms leads to changes in STAT3 activation. Oncotarget 2023; 14:366-376. [PMID: 37097001 DOI: 10.18632/oncotarget.28412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023] Open
Abstract
Signal transducer and activator of transcription 3 (STAT3) is a transcription factor involved in multiple fundamental biological processes and a key player in cancer development and progression. STAT3 is activated upon tyrosine phosphorylation and is constitutively active in various malignancies; therefore, the expression of pSTAT3 has been recognized as a predictor of poor survival. STAT3 encodes two alternatively-spliced STAT3 isoforms: the full-length STAT3α isoform and the truncated STAT3β isoform. These isoforms have been suggested as the reason for the occasionally observed opposing roles of STAT3 in cancer: an oncogene, on one hand, and a tumor suppressor on the other. To investigate their roles in aggressive breast cancer, we separately silenced each isoform and found that they affect each other's activation, impacting cell viability, cytokine expression, and migration. Silencing specific isoforms can lead to a more favorable balance of activated STAT3 proteins in the cell. Distinguishing between the two isoforms and their active forms is crucial for STAT3-related cancer diagnosis and therapy.
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Affiliation(s)
- Inbal Shamir
- Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center, Ramat-Gan, Israel
| | - Ilan Tsarfaty
- Department of Clinical Microbiology and Immunology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Gidi Paret
- Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center, Ramat-Gan, Israel
| | - Yael Nevo-Caspi
- Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center, Ramat-Gan, Israel
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Zheng ZY, Yang PL, Luo W, Yu SX, Xu HY, Huang Y, Li RY, Chen Y, Xu XE, Liao LD, Wang SH, Huang HC, Li EM, Xu LY. STAT3β Enhances Sensitivity to Concurrent Chemoradiotherapy by Inducing Cellular Necroptosis in Esophageal Squamous Cell Carcinoma. Cancers (Basel) 2021; 13:cancers13040901. [PMID: 33670049 PMCID: PMC7926856 DOI: 10.3390/cancers13040901] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/12/2021] [Accepted: 02/14/2021] [Indexed: 02/05/2023] Open
Abstract
Concurrent chemoradiotherapy (CCRT), especially platinum plus radiotherapy, is considered to be one of the most promising treatment modalities for patients with advanced esophageal cancer. STAT3β regulates specific target genes and inhibits the process of tumorigenesis and development. It is also a good prognostic marker and a potential marker for response to adjuvant chemoradiotherapy (ACRT). We aimed to investigate the relationship between STAT3β and CCRT. We examined the expression of STAT3α and STAT3β in pretreatment tumor biopsies of 105 ESCC patients who received CCRT by immunohistochemistry. The data showed that ESCC patients who demonstrate both high STAT3α expression and high STAT3β expression in the cytoplasm have a significantly better survival rate, and STAT3β expression is an independent protective factor (HR = 0.424, p = 0.003). Meanwhile, ESCC patients with high STAT3β expression demonstrated a complete response to CCRT in 65 patients who received platinum plus radiation therapy (p = 0.014). In ESCC cells, high STAT3β expression significantly inhibits the ability of colony formation and cell proliferation, suggesting that STAT3β enhances sensitivity to CCRT (platinum plus radiation therapy). Mechanistically, through RNA-seq analysis, we found that the TNF signaling pathway and necrotic cell death pathway were significantly upregulated in highly expressed STAT3β cells after CCRT treatment. Overall, our study highlights that STAT3β could potentially be used to predict the response to platinum plus radiation therapy, which may provide an important insight into the treatment of ESCC.
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Affiliation(s)
- Zhen-Yuan Zheng
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, China
| | - Ping-Lian Yang
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
| | - Wei Luo
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
| | - Shuai-Xia Yu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
| | - Hong-Yao Xu
- Departments of Radiation Oncology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou 515041, China; (H.-Y.X.); (H.-C.H.)
| | - Ying Huang
- Departments of Pathology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou 515041, China; (Y.H.); (S.-H.W.)
| | - Rong-Yao Li
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, China
| | - Yang Chen
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
| | - Xiu-E Xu
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
| | - Lian-Di Liao
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
| | - Shao-Hong Wang
- Departments of Pathology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou 515041, China; (Y.H.); (S.-H.W.)
| | - He-Cheng Huang
- Departments of Radiation Oncology, Shantou Central Hospital, Affiliated Shantou Hospital of Sun Yat-sen University, Shantou 515041, China; (H.-Y.X.); (H.-C.H.)
| | - En-Min Li
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, China
- Correspondence: (E.-M.L.); (L.-Y.X.)
| | - Li-Yan Xu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, China; (Z.-Y.Z.); (P.-L.Y.); (W.L.); (S.-X.Y.); (R.-Y.L.); (Y.C.)
- Institute of Oncologic Pathology, Shantou University Medical College, Shantou 515041, China; (X.-E.X.); (L.-D.L.)
- Correspondence: (E.-M.L.); (L.-Y.X.)
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Sommerhalder C, Cummins CB, Wang X, Ramdas D, Lopez ON, Gu Y, Zhou J, Radhakrishnan RS. HJC0416 Attenuates Fibrogenesis in Activated Hepatic Stellate Cells via STAT3 and NF-κB Pathways. J Surg Res 2021; 261:334-342. [PMID: 33486415 DOI: 10.1016/j.jss.2020.12.045] [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: 02/28/2020] [Revised: 10/31/2020] [Accepted: 12/04/2020] [Indexed: 10/22/2022]
Abstract
BACKGROUND Hepatic fibrosis is wound-healing response that is the result of hepatic stellate cell (HSC) activation and subsequent excess extracellular matrix deposition. HSCs can be activated by a variety of inflammatory stimuli as well as through the signal transducer and activator of transcription 3 (STAT3) pathway. HJC0416 is a novel, orally bioavailable small-molecule inhibitor of STAT3 that was developed by our team using a fragment-based drug design approach. Previously, our team has shown that HJC0416 has antifibrogenic effects in activated HSCs. Recently, increasing evidence suggests that nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) plays an important role in the activation of HSCs. In the present study, we examined the role of NF-κB inhibition of HSC activation by HJC0416. METHODS LX-2 (human) and HSC-T6 (rat) cell lines were used. Expression levels of extracellular proteins, NF-κB and STAT3 expression and DNA binding, and inflammatory cytokine levels were determined using western blot, ELISA, and immunofluorescence assay. RESULTS HJC0416 decreased cell viability in a dose-dependent manner in both cell lines and arrested the cell cycle at the S phase. Increased apoptosis was seen in LX-2 cells through Yo-Pro-1 and propidium iodide immunofluorescent stating. HJC0416 significantly decreased expression of fibronectin and collagen I as well as markedly decreased α-SMA and laminin. HJC0416 inhibited the STAT3 pathway by decreasing phosphorylation of STAT3, as well as signal transduction pathway activation. Notably, HJC0416 also inhibited the classic and alternative pathways of NF-κB activation. HJC0416 inhibited LPS-induced p65 nuclear translocation and DNA binding, as well as prevented phosphorylation and degradation of inhibitory protein IκBα. HJC0416 also prevented phosphorylation of serine residue 536 on p65. CONCLUSIONS HJC0416, an inhibitor of STAT3, was found to have antifibrogenic properties in activated hepatic stellate cell lines. In addition, HJC0416 was found to inhibit the NF-κB pathway. Owing to this double effect, HJC0416 demonstrates promise for in vivo experimentation as an antifibrosis treatment.
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Affiliation(s)
| | - Claire B Cummins
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas
| | - Xiaofu Wang
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas
| | - Divya Ramdas
- School of Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Omar Nunez Lopez
- Department of Surgery, University of Texas Medical Branch, Galveston, Texas
| | - Yanping Gu
- Department of Neuroscience, University of Texas Medical Branch, Galveston, Texas
| | - Jia Zhou
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas
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STAT3β is a tumor suppressor in acute myeloid leukemia. Blood Adv 2020; 3:1989-2002. [PMID: 31270081 DOI: 10.1182/bloodadvances.2018026385] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 05/04/2019] [Indexed: 12/17/2022] Open
Abstract
Signal transducer and activator of transcription 3 (STAT3) exists in 2 alternatively spliced isoforms, STAT3α and STAT3β. Although truncated STAT3β was originally postulated to act as a dominant-negative form of STAT3α, it has been shown to have various STAT3α-independent regulatory functions. Recently, STAT3β gained attention as a powerful antitumorigenic molecule in cancer. Deregulated STAT3 signaling is often found in acute myeloid leukemia (AML); however, the role of STAT3β in AML remains elusive. Therefore, we analyzed the STAT3β/α messenger RNA (mRNA) expression ratio in AML patients, where we observed that a higher STAT3β/α mRNA ratio correlated with a favorable prognosis and increased overall survival. To gain better understanding of the function of STAT3β in AML, we engineered a transgenic mouse allowing for balanced Stat3β expression. Transgenic Stat3β expression resulted in decelerated disease progression and extended survival in PTEN- and MLL-AF9-dependent AML mouse models. Our findings further suggest that the antitumorigenic function of STAT3β depends on the tumor-intrinsic regulation of a small set of significantly up- and downregulated genes, identified via RNA sequencing. In conclusion, we demonstrate that STAT3β plays an essential tumor-suppressive role in AML.
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7
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Gu Y, Mohammad IS, Liu Z. Overview of the STAT-3 signaling pathway in cancer and the development of specific inhibitors. Oncol Lett 2020; 19:2585-2594. [PMID: 32218808 PMCID: PMC7068531 DOI: 10.3892/ol.2020.11394] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 12/19/2019] [Indexed: 12/11/2022] Open
Abstract
Signal transducer and activator of transcription (STAT) proteins represent novel therapeutic targets for the treatment of cancer. In particular, STAT-3 serves critical roles in several cellular processes, including the cell cycle, cell proliferation, cellular apoptosis and tumorigenesis. Persistent activation of STAT-3 has been reported in a variety of cancer types, and a poor prognosis of cancer may be associated with the phosphorylation level of STAT-3. Furthermore, elevated STAT-3 activity has been demonstrated in a variety of mammalian cancers, both in vitro and in vivo. This indicates that STAT-3 serves an important role in the progression of numerous cancer types. A significant obstacle in developing STAT-3 inhibitors is the demonstration of the antitumor efficacy in in vivo systems and the lack of animal models for human tumors. Therefore, it is crucial to determine whether available STAT-3 inhibitors are suitable for clinical trials. Moreover, further preclinical studies are necessary to focus on the impact of STAT-3 inhibitors on tumor cells. When considering STAT-3 hyper-activation in human cancer, selective targeting to these proteins holds promise for significant advancement in cancer treatment. In the present study, advances in our knowledge of the structure of STAT-3 protein and its regulatory mechanisms are summarized. Moreover, the STAT-3 signaling pathway and its critical role in malignancy are discussed, in addition to the development of STAT-3 inhibitors in various cancer types.
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Affiliation(s)
- Yuchen Gu
- Department of Pharmacy, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233000, P.R. China.,College of Pharmacy, Bengbu Medical College, Bengbu, Anhui 233000, P.R. China
| | - Imran Shair Mohammad
- School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou, Guangdong 510006, P.R. China
| | - Zhe Liu
- Department of Pharmacy, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui 233000, P.R. China.,College of Pharmacy, Bengbu Medical College, Bengbu, Anhui 233000, P.R. China
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A deep intronic splice mutation of STAT3 underlies hyper IgE syndrome by negative dominance. Proc Natl Acad Sci U S A 2019; 116:16463-16472. [PMID: 31346092 DOI: 10.1073/pnas.1901409116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Heterozygous in-frame mutations in coding regions of human STAT3 underlie the only known autosomal dominant form of hyper IgE syndrome (AD HIES). About 5% of familial cases remain unexplained. The mutant proteins are loss-of-function and dominant-negative when tested following overproduction in recipient cells. However, the production of mutant proteins has not been detected and quantified in the cells of heterozygous patients. We report a deep intronic heterozygous STAT3 mutation, c.1282-89C>T, in 7 relatives with AD HIES. This mutation creates a new exon in the STAT3 complementary DNA, which, when overexpressed, generates a mutant STAT3 protein (D427ins17) that is loss-of-function and dominant-negative in terms of tyrosine phosphorylation, DNA binding, and transcriptional activity. In immortalized B cells from these patients, the D427ins17 protein was 2 kDa larger and 4-fold less abundant than wild-type STAT3, on mass spectrometry. The patients' primary B and T lymphocytes responded poorly to STAT3-dependent cytokines. These findings are reminiscent of the impaired responses of leukocytes from other patients with AD HIES due to typical STAT3 coding mutations, providing further evidence for the dominance of the mutant intronic allele. These findings highlight the importance of sequencing STAT3 introns in patients with HIES without candidate variants in coding regions and essential splice sites. They also show that AD HIES-causing STAT3 mutant alleles can be dominant-negative even if the encoded protein is produced in significantly smaller amounts than wild-type STAT3.
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STAT3 isoforms: Alternative fates in cancer? Cytokine 2019; 118:27-34. [DOI: 10.1016/j.cyto.2018.07.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 07/10/2018] [Accepted: 07/11/2018] [Indexed: 02/04/2023]
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10
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Zhang HX, Yang PL, Li EM, Xu LY. STAT3beta, a distinct isoform from STAT3. Int J Biochem Cell Biol 2019; 110:130-139. [PMID: 30822557 DOI: 10.1016/j.biocel.2019.02.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Revised: 02/08/2019] [Accepted: 02/20/2019] [Indexed: 02/05/2023]
Abstract
STAT3β is an isoform of STAT3 (signal transducer and activator of transcription 3) that differs from the STAT3α isoform by the replacement of the C-terminal 55 amino acid residues with 7 specific residues. The constitutive activation of STAT3α plays a pivotal role in the activation of oncogenic pathways, such as cell proliferation, maturation and survival, while STAT3β is often referred to as a dominant-negative regulator of cancer. STAT3β reveals a "spongy cushion" effect through its cooperation with STAT3α or forms a ternary complex with other co-activators. Especially in tumour cells, relatively high levels of STAT3β lead to some favourable changes. However, there are still many mechanisms that have not been clearly explained in contrast to STAT3α, such as STAT3β nuclear retention, more stable heterodimers and the prolonged Y705 phosphorylation. In addition to its transcriptional activities, STAT3β may also function in the cytosol with respect to the mitochondria, cytoskeleton rearrangements and metastasis of cancer cells. In this review, we summarize the mechanisms that underlie the unique roles of STAT3β combined with total STAT3 to enlighten and draw the attention of researchers studying STAT3 and discuss some interesting questions that warrant answers.
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Affiliation(s)
- Hui-Xiang Zhang
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, Guangdong, PR China; Institute of Oncological Pathology, Shantou University Medical College, Shantou, Guangdong, PR China
| | - Ping-Lian Yang
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, Guangdong, PR China; Institute of Oncological Pathology, Shantou University Medical College, Shantou, Guangdong, PR China
| | - En-Min Li
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, Guangdong, PR China; Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, Guangdong, PR China.
| | - Li-Yan Xu
- The Key Laboratory of Molecular Biology for High Cancer Incidence Coastal Chaoshan Area, Shantou University Medical College, Shantou 515041, Guangdong, PR China; Institute of Oncological Pathology, Shantou University Medical College, Shantou, Guangdong, PR China.
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PARP-1 Is Critical for Recruitment of Dendritic Cells to the Lung in a Mouse Model of Asthma but Dispensable for Their Differentiation and Function. Mediators Inflamm 2019; 2019:1656484. [PMID: 31178661 PMCID: PMC6507252 DOI: 10.1155/2019/1656484] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/15/2018] [Accepted: 01/02/2019] [Indexed: 02/01/2023] Open
Abstract
Dendritic cells (DCs) are critical in asthma and many other immune diseases. We previously demonstrated a role for PARP-1 in asthma. Evidence on PARP-1 playing a role in Th2-associated DC function is not clear. In this study, we examined whether PARP-1 is critical for DC differentiation and function using bone marrow progenitors and their migration to the lung in an ovalbumin-based mouse model of asthma. Results show that changes in PARP-1 levels during GM-CSF-induced DC differentiation from bone marrow progenitors were cyclic and appear to be part of an array of changes that included STAT3/STAT5/STAT6/GRAIL/RAD51. Interestingly, PARP-1 gene deletion affected primarily STAT6 and γH2AX. PARP-1 inhibition significantly reduced the migration of DCs to the lungs of ovalbumin-challenged mice, which was associated with a concomitant reduction in lung levels of the adhesion molecule VCAM-1. The requirement of PARP-1 for VCAM-1 expression was confirmed using endothelial and lung smooth muscle cells. PARP-1 expression and activity were also required for VCAM-1 in differentiated DCs. An assessment of CD11b+/CD11c+/MHCIIhigh DCs in spleens and lymph nodes of OVA-sensitized mice revealed that PARP-1 inhibition genetically or by olaparib exerted little to no effect on DC differentiation, percentage of CD80+/CD86+/CD40+-expressing cells, or their capacity to promote proliferation of ovalbumin-primed (OTII) CD4+ T cells. These findings were corroborated using GM-CSF-induced differentiation of DCs from the bone marrow. Surprisingly, the PARP-1−/− DCs exhibited a higher intrinsic capacity to induce OTII CD4+ T cell proliferation in the absence of ovalbumin. Overall, our results show that PARP-1 plays little to no role in DC differentiation and function and that the protective effect of PARP-1 inhibition against asthma is associated with a prevention of DC migration to the lung through a reduction in VCAM-1 expression. Given the current use of PARP inhibitors (e.g., olaparib) in the clinic, the present results may be of interest for the relevant therapies.
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Wang X, Du L, Wei H, Zhang A, Yang K, Zhou H. Identification of two Stat3 variants lacking a transactivation domain in grass carp: New insights into alternative splicing in the modification of teleost Stat3 signaling. FISH & SHELLFISH IMMUNOLOGY 2018; 77:13-21. [PMID: 29555584 DOI: 10.1016/j.fsi.2018.03.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 06/08/2023]
Abstract
Signal transducer and activator of transcription 3 (STAT3) is a member of the STAT family in response to cytokines and growth factors. In mammals, alternative splicing of STAT3 generates STAT3α and STAT3β, which have distinct and overlapping functions. In the previous study, we have identified two spliceforms of Stat3α (Stat3α1 and Stat3α2) possessing all functional domains of Stat3 in grass carp (Ctenopharyngodon idella). In the present study, two Stat3β variants (Stat3β1 and Stat3β2) without C-terminal transactivation domain were isolated from this species, and their transcripts were ubiquitously expressed in all examined tissues with the highest levels in liver. Further studies showed that Stat3β1/2 had the ability to translocate into the nucleus upon activation, indicating their roles in transcriptional regulation. In support of this notion, grass carp Stat3β1 and Stat3β2 displayed the abilities to inhibit Interleukin-10 (Il-10) signaling and competitively impaired the transcriptional activities of Stat3α1/2. In particular, similar to their mammalian counterparts, grass carp Stat3β1 and Stat3β2 could enhance Stat3α1/2 phosphorylation upon cytokine stimulation. Interestingly, stat3β1 and stat3β2 transcripts were also found in zebrafish (Danio rerio) and goldfish (Carassius auratus), and each variant in these teleosts is generated through similar alternative splicing events, including exon skipping and intron retention. This highlights a conserved splicing event of stat3 gene during vertebrate evolution and indicates a potential physiological significance of generating unique Stat3 variants in fish. These results, along with the findings regarding Stat3α1/2, demonstrate the existence of Stat3 isoforms with functional diversity and redundancy in teleosts. It leads to the hypothesis that teleost-specific spliceforms of Stat3 gene may contribute to the complexity of Stat3 signaling in fishes, thereby benefiting them to adapt to evolution and environmental changes.
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Affiliation(s)
- Xinyan Wang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
| | - Linyong Du
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
| | - He Wei
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
| | - Anying Zhang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
| | - Kun Yang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
| | - Hong Zhou
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
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Cummins CB, Wang X, Nunez Lopez O, Graham G, Tie HY, Zhou J, Radhakrishnan RS. Luteolin-Mediated Inhibition of Hepatic Stellate Cell Activation via Suppression of the STAT3 Pathway. Int J Mol Sci 2018; 19:ijms19061567. [PMID: 29795016 PMCID: PMC6032316 DOI: 10.3390/ijms19061567] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/18/2018] [Accepted: 05/22/2018] [Indexed: 12/31/2022] Open
Abstract
Hepatic stellate cell (HSC) activation is responsible for hepatic fibrogenesis and is associated with an overexpression of transcription 3 (STAT3). Luteolin, a common dietary flavonoid with potent anti-inflammatory properties, has previously demonstrated antifibrogenic properties in HSCs but the mechanism has not been fully elucidated. Activated human and rat hepatic stellate cell lines LX-2 and HSC-T6 were used to study the effects of luteolin on HSCs. Cellular proteins were determined by western blot and immunofluorescence. Cell proliferation was assessed with Alamar Blue assay. Luteolin significantly decreased LX-2 and HSC-T6 cell viability in a time-and-dose-dependent manner, as well as decreased HSC end-products α-smooth muscle actin (α-SMA), collagen I, and fibronectin. Luteolin decreased levels of total and phosphorylated STAT3, suppressed STAT3 nuclear translocation and transcriptional activity, and attenuated expression of STAT3-regulated proteins c-myc and cyclin D1. STAT3 specific inhibitors stattic and SH-4-54 demonstrated similar effects on HSC viability and α-SMA production. In LX-2 and HSC-T6 cells, luteolin demonstrates a potent ability to inhibit hepatic fibrogenesis via suppression of the STAT3 pathway. These results further elucidate the mechanism of luteolin as well as the effect of the STAT3 pathway on HSC activation.
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Affiliation(s)
- Claire B Cummins
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Xiaofu Wang
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Omar Nunez Lopez
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Gabriel Graham
- School of Medicine, Alabama College of Osteopathic Medicine, Dothan, AL 36303, USA.
| | - Hong-Yan Tie
- Department of Anatomy, College of Basic Medicine, Zhengzhou University, Zhengzhou 450066, China.
| | - Jia Zhou
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Ravi S Radhakrishnan
- Department of Surgery, University of Texas Medical Branch, Galveston, TX 77555, USA.
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14
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Goldberg L, Abutbul-Amitai M, Paret G, Nevo-Caspi Y. Alternative Splicing of STAT3 Is Affected by RNA Editing. DNA Cell Biol 2017; 36:367-376. [PMID: 28278381 DOI: 10.1089/dna.2016.3575] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A-to-I RNA editing, carried out by adenosine deaminase acting on RNA (ADAR) enzymes, is an epigenetic phenomenon of posttranscriptional modifications on pre-mRNA. RNA editing in intronic sequences may influence alternative splicing of flanking exons. We have previously shown that conditions that induce editing result in elevated expression of signal transducer and activator of transcription 3 (STAT3), preferentially the alternatively-spliced STAT3β isoform. Mechanisms regulating alternative splicing of STAT3 have not been elucidated. STAT3 undergoes A-to-I RNA editing in an intron residing in proximity to the alternatively spliced exon. We hypothesized that RNA editing plays a role in regulating alternative splicing toward STAT3β. In this study we extend our observation connecting RNA editing to the preferential induction of STAT3β expression. We study the involvement of ADAR1 in STAT3 editing and reveal the connection between editing and alternative splicing of STAT3. Deferoaxamine treatment caused the induction in STAT3 RNA editing and STAT3β expression. Silencing ADAR1 caused a decrease in STAT3 editing and expression with a preferential decrease in STAT3β. Cells transfected with a mutated minigene showed preferential splicing toward the STAT3β transcript. Editing in the STAT3 intron is performed by ADAR1 and affects STAT3 alternative splicing. These results suggest that RNA editing is one of the molecular mechanisms regulating the expression of STAT3β.
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Affiliation(s)
- Lior Goldberg
- 1 Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center , Tel Hashomer, Israel .,2 Sackler Medical School, Tel-Aviv University , Tel-Aviv, Israel
| | - Mor Abutbul-Amitai
- 1 Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center , Tel Hashomer, Israel .,2 Sackler Medical School, Tel-Aviv University , Tel-Aviv, Israel
| | - Gideon Paret
- 1 Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center , Tel Hashomer, Israel .,2 Sackler Medical School, Tel-Aviv University , Tel-Aviv, Israel
| | - Yael Nevo-Caspi
- 1 Department of Pediatric Critical Care Medicine, Safra Children's Hospital, Sheba Medical Center , Tel Hashomer, Israel
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15
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Tapia VS, Herrera‐Rojas M, Larrain J. JAK-STAT pathway activation in response to spinal cord injury in regenerative and non-regenerative stages of Xenopus laevis. REGENERATION (OXFORD, ENGLAND) 2017; 4:21-35. [PMID: 28316792 PMCID: PMC5350081 DOI: 10.1002/reg2.74] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/17/2017] [Accepted: 01/18/2017] [Indexed: 12/13/2022]
Abstract
Xenopus laevis tadpoles can regenerate the spinal cord after injury but this capability is lost during metamorphosis. Comparative studies between pre-metamorphic and metamorphic Xenopus stages can aid towards understanding the molecular mechanisms of spinal cord regeneration. Analysis of a previous transcriptome-wide study suggests that, in response to injury, the JAK-STAT pathway is differentially activated in regenerative and non-regenerative stages. We characterized the activation of the JAK-STAT pathway and found that regenerative tadpoles have an early and transient activation. In contrast, the non-regenerative stages have a delayed and sustained activation of the pathway. We found that STAT3 is activated in response to injury mainly in Sox2/3+ ependymal cells, motoneurons and sensory neurons. Finally, to study the role of temporal activation we generated a transgenic line to express a constitutively active version of STAT3. The sustained activation of the JAK-STAT pathway in regenerative tadpoles reduced the expression of pro-neurogenic genes normally upregulated in response to spinal cord injury, suggesting that activation of the JAK-STAT pathway modulates the fate of neural progenitors.
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Affiliation(s)
- Victor S. Tapia
- Center for Aging and RegenerationMillennium Nucleus in Regenerative BiologyFacultad de Ciencias BiologicasPontificia Universidad Catolica de ChileSantiagoChile
| | - Mauricio Herrera‐Rojas
- Center for Aging and RegenerationMillennium Nucleus in Regenerative BiologyFacultad de Ciencias BiologicasPontificia Universidad Catolica de ChileSantiagoChile
| | - Juan Larrain
- Center for Aging and RegenerationMillennium Nucleus in Regenerative BiologyFacultad de Ciencias BiologicasPontificia Universidad Catolica de ChileSantiagoChile
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16
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Lopez ON, Bohanon FJ, Wang X, Ye N, Corsello T, Rojas-Khalil Y, Chen H, Chen H, Zhou J, Radhakrishnan RS. STAT3 Inhibition Suppresses Hepatic Stellate Cell Fibrogenesis: HJC0123, a Potential Therapeutic Agent for Liver Fibrosis. RSC Adv 2016; 6:100652-100663. [PMID: 28546859 PMCID: PMC5440088 DOI: 10.1039/c6ra17459k] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Hepatic Stellate Cells (HSCs) are the major source of the excessive extracellular matrix (ECM) production that replaces liver parenchyma with fibrous tissue during liver fibrosis. The signal transducer and activator of transcription 3 (STAT3) promotes HCSs survival, proliferation, and activation contributing to fibrogenesis. We have previously used a fragment-based drug design approach and have discovered a novel STAT3 inhibitor, HJC0123. Here, we explored the biological effects of HJC0123 on the fibrogenic properties of HSCs. HJC0123 treatment resulted in the inhibition of HSCs proliferation at submicromolar concentrations. HJC0123 reduced the phosphorylation, nuclear translocation, and transcriptional activity of STAT3. It decreased the expression of STAT3-regulated proteins, induced cell cycle arrest, promoted apoptosis and downregulated SOCS3. HJC0123 treatment inhibited HSCs activation and downregulated ECM protein fibronectin and type I collagen expression. In addition, HJC0123 increased IL-6 production and decreased TGF-β induced Smad2/3 phosphorylation. These results demonstrate that HJC0123 represents a novel STAT3 inhibitor that suppresses the fibrogenic properties of HSCs, suggesting its therapeutic potential in liver fibrosis.
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Affiliation(s)
- Omar Nunez Lopez
- Department of Surgery, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Fredrick J. Bohanon
- Department of Surgery, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Xiaofu Wang
- Department of Surgery, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Na Ye
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Tiziana Corsello
- Department of Surgery, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Yesenia Rojas-Khalil
- Department of Surgery, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Haijun Chen
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Haiying Chen
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Jia Zhou
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
- Department of Pediatrics, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
| | - Ravi S. Radhakrishnan
- Department of Surgery, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
- Department of Pediatrics, University of Texas Medical Branch, 301 University Blvd., Galveston, TX, USA, 77555
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17
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Lewis KM, Bharadwaj U, Eckols TK, Kolosov M, Kasembeli MM, Fridley C, Siller R, Tweardy DJ. Small-molecule targeting of signal transducer and activator of transcription (STAT) 3 to treat non-small cell lung cancer. Lung Cancer 2015; 90:182-90. [PMID: 26410177 PMCID: PMC4619129 DOI: 10.1016/j.lungcan.2015.09.014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/14/2015] [Accepted: 09/14/2015] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Lung cancer is the leading cause of cancer death in both men and women. Non-small cell lung cancer (NSCLC) has an overall 5-year survival rate of 15%. While aberrant STAT3 activation has previously been observed in NSCLC, the scope of its contribution is uncertain and agents that target STAT3 for treatment are not available clinically. METHODS We determined levels of activated STAT3 (STAT3 phosphorylated on Y705, pSTAT3) and the two major isoforms of STAT3 (α and β) in protein extracts of 8 NSCLC cell lines, as well as the effects of targeting STAT3 in vitro and in vivo in NSCLC cells using short hairpin (sh) RNA and two novel small-molecule STAT3 inhibitors, C188-9 and piperlongumine (PL). RESULTS Levels of pSTAT3, STAT3α, and STATβ were increased in 7 of 8 NSCLC cell lines. Of note, levels of pSTAT3 were tightly correlated with levels of STAT3β, but not STAT3α. Targeting of STAT3 in A549 cells using shRNA decreased tSTAT3 by 75%; this was accompanied by a 47-78% reduction in anchorage-dependent and anchorage-independent growth and a 28-45% reduction in mRNA levels for anti-apoptotic STAT3 gene targets. C188-9 and PL (@30 μM) each reduced pSTAT3 levels in all NSCLC cell lines tested by ≥50%, reduced anti-apoptotic protein mRNA levels by 25-60%, and reduced both anchorage-dependent and anchorage-independent growth of NSCLC cell lines with IC50 values ranging from 3.06 to 52.44 μM and 0.86 to 11.66 μM, respectively. Treatment of nude mice bearing A549 tumor xenografts with C188-9 or PL blocked tumor growth and reduced levels of pSTAT3 and mRNA encoding anti-apoptotic proteins. CONCLUSION STAT3 is essential for growth of NSCLC cell lines and tumors and its targeting using C188-9 or PL may be a useful strategy for treatment.
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Affiliation(s)
- Katherine M Lewis
- Section of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Uddalak Bharadwaj
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - T Kris Eckols
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Mikhail Kolosov
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Moses M Kasembeli
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Colleen Fridley
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Ricardo Siller
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - David J Tweardy
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, TX, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.
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18
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Kramer AH, Kadye R, Houseman PS, Prinsloo E. Mitochondrial STAT3 and reactive oxygen species: A fulcrum of adipogenesis? JAKSTAT 2015; 4:e1084084. [PMID: 27127727 DOI: 10.1080/21623996.2015.1084084] [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: 06/09/2015] [Revised: 08/07/2015] [Accepted: 08/11/2015] [Indexed: 02/08/2023] Open
Abstract
The balance between cellular lineages can be controlled by reactive oxygen species (ROS). Cellular differentiation into adipocytes is highly dependent on the production of ROS to initiate the process through activation of multiple interlinked factors that stimulate mitotic clonal expansion and cellular maturation. The signal transducer and activator of transcription family of signaling proteins have accepted roles in adipogenesis and associated lipogenesis. Non-canonical mitochondrial localization of STAT3 and other members of the STAT family however opens up new avenues for investigation of its role in the aforementioned processes. Following recent observations of differences in mitochondrially localized serine 727 phosphorylated STAT3 (mtSTAT3-pS727) in preadipocytes and adipocytes, here, we hypothesize and speculate further on the role of mitochondrial STAT3 in adipogenesis.
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Affiliation(s)
- Adam H Kramer
- Biotechnology Innovation Center; Rhodes University ; Grahamstown, South Africa
| | - Rose Kadye
- Biotechnology Innovation Center; Rhodes University ; Grahamstown, South Africa
| | | | - Earl Prinsloo
- Biotechnology Innovation Center; Rhodes University ; Grahamstown, South Africa
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19
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Wake MS, Watson CJ. STAT3 the oncogene - still eluding therapy? FEBS J 2015; 282:2600-11. [DOI: 10.1111/febs.13285] [Citation(s) in RCA: 152] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/04/2015] [Accepted: 03/26/2015] [Indexed: 02/06/2023]
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20
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Bharadwaj U, Eckols TK, Kolosov M, Kasembeli MM, Adam A, Torres D, Zhang X, Dobrolecki LE, Wei W, Lewis MT, Dave B, Chang JC, Landis MD, Creighton CJ, Mancini MA, Tweardy DJ. Drug-repositioning screening identified piperlongumine as a direct STAT3 inhibitor with potent activity against breast cancer. Oncogene 2015; 34:1341-53. [PMID: 24681959 PMCID: PMC4182178 DOI: 10.1038/onc.2014.72] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 02/15/2014] [Accepted: 02/17/2014] [Indexed: 12/12/2022]
Abstract
Signal transducer and activator of transcription (STAT) 3 regulates many cardinal features of cancer including cancer cell growth, apoptosis resistance, DNA damage response, metastasis, immune escape, tumor angiogenesis, the Warburg effect and oncogene addiction and has been validated as a drug target for cancer therapy. Several strategies have been used to identify agents that target Stat3 in breast cancer but none has yet entered into clinical use. We used a high-throughput fluorescence microscopy search strategy to identify compounds in a drug-repositioning library (Prestwick library) that block ligand-induced nuclear translocation of Stat3 and identified piperlongumine (PL), a natural product isolated from the fruit of the pepper Piper longum. PL inhibited Stat3 nuclear translocation, inhibited ligand-induced and constitutive Stat3 phosphorylation, and modulated expression of multiple Stat3-regulated genes. Surface plasmon resonance assay revealed that PL directly inhibited binding of Stat3 to its phosphotyrosyl peptide ligand. Phosphoprotein antibody array analysis revealed that PL does not modulate kinases known to activate Stat3 such as Janus kinases, Src kinase family members or receptor tyrosine kinases. PL inhibited anchorage-independent and anchorage-dependent growth of multiple breast cancer cell lines having increased pStat3 or total Stat3, and induced apoptosis. PL also inhibited mammosphere formation by tumor cells from patient-derived xenografts. PL's antitumorigenic function was causally linked to its Stat3-inhibitory effect. PL was non-toxic in mice up to a dose of 30 mg/kg/day for 14 days and caused regression of breast cancer cell line xenografts in nude mice. Thus, PL represents a promising new agent for rapid entry into the clinic for use in treating breast cancer, as well as other cancers in which Stat3 has a role.
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Affiliation(s)
- U Bharadwaj
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - T K Eckols
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - M Kolosov
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - M M Kasembeli
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - A Adam
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - D Torres
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - X Zhang
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, USA
| | - L E Dobrolecki
- Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, USA
| | - W Wei
- 1] Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, USA [2] Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - M T Lewis
- 1] Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX, USA [2] Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA [3] Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA [4] Department of Radiology, Baylor College of Medicine, Houston, TX, USA
| | - B Dave
- The Methodist Cancer Center, The Methodist Hospital Research Institute, Houston, TX, USA
| | - J C Chang
- The Methodist Cancer Center, The Methodist Hospital Research Institute, Houston, TX, USA
| | - M D Landis
- The Methodist Cancer Center, The Methodist Hospital Research Institute, Houston, TX, USA
| | - C J Creighton
- Section of Hematology-Oncology, Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - M A Mancini
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - D J Tweardy
- 1] Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX, USA [2] Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA [3] Department of Radiology, Baylor College of Medicine, Houston, TX, USA
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21
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Szafran AT, Mancini MA. The myImageAnalysis project: a web-based application for high-content screening. Assay Drug Dev Technol 2014; 12:87-99. [PMID: 24547743 DOI: 10.1089/adt.2013.532] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
A major challenge faced by screening centers developing image-based assays is the wide range of assays needed compared to the limited resources that are available to effectively analyze and manage them. To overcome this limitation, we have developed the web-based myImageAnalysis (mIA) application, integrated with an open database connectivity compliant database and powered by Pipeline Pilot (PLP) that incorporates dataset tracking, scheduling and archiving, image analysis, and data reporting. For system administrators, mIA provides automated methods for managing and archiving data. For the biologist, this application allows those without any programming or image analysis experience to quickly develop, validate, and share results of complex image-based assays. Further, the structure of the application within PLP allows those with experience in PLP programming to easily add additional analysis tools as required. The tools within mIA allow users to assess basic (cell count, protein per cell, protein subcellular localization) and more advanced (engineered cell lines analysis, cell toxicity) biological image-based assays that employ advanced statistics and provides key assay performance metrics.
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Affiliation(s)
- Adam T Szafran
- Department of Molecular and Cellular Biology, Baylor College of Medicine , Houston, Texas
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22
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Bharadwaj U, Kasembeli MM, Eckols TK, Kolosov M, Lang P, Christensen K, Edwards DP, Tweardy DJ. Monoclonal Antibodies Specific for STAT3β Reveal Its Contribution to Constitutive STAT3 Phosphorylation in Breast Cancer. Cancers (Basel) 2014; 6:2012-34. [PMID: 25268166 PMCID: PMC4276954 DOI: 10.3390/cancers6042012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 09/15/2014] [Accepted: 09/17/2014] [Indexed: 12/04/2022] Open
Abstract
Since its discovery in mice and humans 19 years ago, the contribution of alternatively spliced Stat3, Stat3β, to the overall functions of Stat3 has been controversial. Tyrosine-phosphorylated (p) Stat3β homodimers are more stable, bind DNA more avidly, are less susceptible to dephosphorylation, and exhibit distinct intracellular dynamics, most notably markedly prolonged nuclear retention, compared to pStat3α homodimers. Overexpression of one or the other isoform in cell lines demonstrated that Stat3β acted as a dominant-negative of Stat3α in transformation assays; however, studies with mouse strains deficient in one or the other isoform indicated distinct contributions of Stat3 isoforms to inflammation. Current immunological reagents cannot differentiate Stat3β proteins derived from alternative splicing vs. proteolytic cleavage of Stat3α. We developed monoclonal antibodies that recognize the 7 C-terminal amino acids unique to Stat3β (CT7) and do not cross-react with Stat3α. Immunoblotting studies revealed that levels of Stat3β protein, but not Stat3α, in breast cancer cell lines positively correlated with overall pStat3 levels, suggesting that Stat3β may contribute to constitutive Stat3 activation in this tumor system. The ability to unambiguously discriminate splice alternative Stat3β from proteolytic Stat3β and Stat3α will provide new insights into the contribution of Stat3β vs. Stat3α to oncogenesis, as well as other biological and pathological processes.
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Affiliation(s)
- Uddalak Bharadwaj
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Moses M Kasembeli
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
| | - T Kris Eckols
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Mikhail Kolosov
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Paul Lang
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Kurt Christensen
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Dean P Edwards
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - David J Tweardy
- Section of Infectious Disease, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
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23
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STAT3 in Cancer-Friend or Foe? Cancers (Basel) 2014; 6:1408-40. [PMID: 24995504 PMCID: PMC4190548 DOI: 10.3390/cancers6031408] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 06/19/2014] [Accepted: 06/20/2014] [Indexed: 12/25/2022] Open
Abstract
The roles and significance of STAT3 in cancer biology have been extensively studied for more than a decade. Mounting evidence has shown that constitutive activation of STAT3 is a frequent biochemical aberrancy in cancer cells, and this abnormality directly contributes to tumorigenesis and shapes many malignant phenotypes in cancer cells. Nevertheless, results from more recent experimental and clinicopathologic studies have suggested that STAT3 also can exert tumor suppressor effects under specific conditions. Importantly, some of these studies have demonstrated that STAT3 can function either as an oncoprotein or a tumor suppressor in the same cell type, depending on the specific genetic background or presence/absence of specific coexisting biochemical defects. Thus, in the context of cancer biology, STAT3 can be a friend or foe. In the first half of this review, we will highlight the “evil” features of STAT3 by summarizing its oncogenic functions and mechanisms. The differences between the canonical and non-canonical pathway will be highlighted. In the second half, we will summarize the evidence supporting that STAT3 can function as a tumor suppressor. To explain how STAT3 may mediate its tumor suppressor effects, we will discuss several possible mechanisms, one of which is linked to the role of STAT3β, one of the two STAT3 splicing isoforms. Taken together, it is clear that the roles of STAT3 in cancer are multi-faceted and far more complicated than one appreciated previously. The new knowledge has provided us with new approaches and strategies when we evaluate STAT3 as a prognostic biomarker or therapeutic target.
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Ng IHW, Bogoyevitch MA, Jans DA. Cytokine-induced slowing of STAT3 nuclear import; faster basal trafficking of the STAT3β isoform. Traffic 2014; 15:946-60. [PMID: 24903907 DOI: 10.1111/tra.12181] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 06/02/2014] [Accepted: 06/03/2014] [Indexed: 01/01/2023]
Abstract
The STAT3 signal transducer and activator of transcription is a key mediator of gene transcription in response to cytokines such as oncostatin M (OSM). We performed direct live cell imaging of GFP-tagged STAT3 proteins for the first time, showing transient relocalization of STAT3α to the nucleus following OSM exposure, in contrast to sustained nuclear relocalization of the shorter STAT3β spliceform. To explore this further, we applied fluorescence recovery after photobleaching (FRAP) to determine the nuclear import kinetics of STAT3α and β, as well as of a C-terminal truncation derivative STAT3ΔC comprising only the sequence shared by the spliceforms, in the absence or presence of OSM. The rates of basal nuclear import for STAT3β and STAT3ΔC were significantly faster than those for STAT3α. Strikingly, OSM slowed the import rates of all the three STAT3 proteins, whereas the import rates of GFP alone or a classical importin-mediated cargo were unaffected, with analysis of Y705F mutant derivatives for all the three STAT3 constructs, or of a S727A mutant within the unique C-terminus of STAT3α, reinforcing the contribution of specific phosphorylation to the cytokine-stimulated changes. The results introduce a new paradigm where cytokine treatment prolongs nuclear retention simultaneous with decreasing rather than increasing the rate of nuclear import.
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Affiliation(s)
- Ivan H W Ng
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, 3800, Australia; Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria, 3010, Australia
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Abstract
Silencing of abnormally activated genes can be accomplished in a highly specific manner using nucleic acid based approaches. The focus of this review includes the different nucleic acid based inhibition strategies such as antisense oligodeoxynucleotides, small interfering RNA (siRNA), dominant-negative constructs, G-quartet oligonucleotides and decoy oligonucleotides, their mechanism of action and the effectiveness of these approaches to targeting the STAT (signal transducer and activator of transcription) proteins in cancer. Among the STAT proteins, especially STAT3, followed by STAT5, are the most frequently activated oncogenic STATs, which have emerged as plausible therapeutic cancer targets. Both STAT3 and STAT5 have been shown to regulate numerous oncogenic signaling pathways including proliferation, survival, angiogenesis and migration/invasion.
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Affiliation(s)
- Malabika Sen
- Department of Otolaryngology; University of Pittsburgh School of Medicine; Pittsburgh, PA USA
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Qi QR, Yang ZM. Regulation and function of signal transducer and activator of transcription 3. World J Biol Chem 2014; 5:231-239. [PMID: 24921012 PMCID: PMC4050116 DOI: 10.4331/wjbc.v5.i2.231] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 01/07/2014] [Accepted: 01/20/2014] [Indexed: 02/05/2023] Open
Abstract
Signal transducer and activator of transcription 3 (STAT3), a member of the STAT family, is a key regulator of many physiological and pathological processes. Significant progress has been made in understanding the transcriptional control, posttranslational modification, cellular localization and functional regulation of STAT3. STAT3 can translocate into the nucleus and bind to specific promoter sequences, thereby exerting transcriptional regulation. Recent studies have shown that STAT3 can also translocate into mitochondria, participating in aerobic respiration and apoptosis. In addition, STAT3 plays an important role in inflammation and tumorigenesis by regulating cell proliferation, differentiation and metabolism. Conditional knockout mouse models make it possible to study the physiological function of STAT3 in specific tissues and organs. This review summarizes the latest advances in the understanding of the expression, regulation and function of STAT3 in physiological and tumorigenic processes.
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Ng IHW, Yeap YYC, Ong LSR, Jans DA, Bogoyevitch MA. Oxidative stress impairs multiple regulatory events to drive persistent cytokine-stimulated STAT3 phosphorylation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:483-94. [PMID: 24286865 DOI: 10.1016/j.bbamcr.2013.11.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 10/31/2013] [Accepted: 11/19/2013] [Indexed: 12/30/2022]
Abstract
Although cytokine-driven STAT3 phosphorylation and activation are often transient, persistent activation of STAT3 is a hallmark of a range of pathologies and underpins altered transcriptional responses. As triggers in disease frequently include combined increases in inflammatory cytokine and reactive oxygen species levels, we report here how oxidative stress impacts on cytokine-driven STAT3 signal transduction events. In the model system of murine embryonic fibroblasts (MEFs), combined treatment with the interleukin-6 family cytokine Leukemia Inhibitory Factor (LIF) and hydrogen peroxide (H2O2) drove persistent STAT3 phosphorylation whereas STAT3 phosphorylation increased only transiently in response to LIF alone and was not increased by H2O2 alone. Surprisingly, increases in transcript levels of the direct STAT3 gene target SOCS3 were delayed during the combined LIF + H2O2 treatment, leading us to probe the impact of oxidative stress on STAT3 regulatory events. Indeed, LIF + H2O2 prolonged JAK activation, delayed STAT3 nuclear localisation, and caused relocalisation of nuclear STAT3 phosphatase TC-PTP (TC45) to the cytoplasm. In exploring the nuclear import/ export pathways, we observed disruption of nuclear/cytoplasmic distributions of Ran and importin-alpha3 in cells exposed to H2O2 and the resultant reduced nuclear trafficking of Classical importin-alpha/3-dependent protein cargoes. CRM1-mediated nuclear export persisted despite the oxidative stress insult, with sustained STAT3 Y705 phosphorylation enhancing STAT3 nuclear residency. Our studies thus reveal for the first time the striking impact of oxidative stress to sustain STAT3 phosphorylation and nuclear retention following disruption of multiple regulatory events, with significant implications for STAT3 function.
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Chatzimpaloglou A, Kolosov M, Eckols TK, Tweardy DJ, Sarli V. Synthetic and Biological Studies of Phaeosphaerides. J Org Chem 2014; 79:4043-54. [DOI: 10.1021/jo500545d] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Anthoula Chatzimpaloglou
- Faculty
of Chemistry, Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece
| | - Mikhail Kolosov
- Department
of Medicine, Section of Infectious Diseases, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, United States
| | - T. Kris Eckols
- Department
of Medicine, Section of Infectious Diseases, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, United States
| | - David J. Tweardy
- Department
of Medicine, Section of Infectious Diseases, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, United States
| | - Vasiliki Sarli
- Faculty
of Chemistry, Aristotle University of Thessaloniki, University Campus, 54124 Thessaloniki, Greece
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Kasembeli M, Lau WCY, Roh SH, Eckols TK, Frydman J, Chiu W, Tweardy DJ. Modulation of STAT3 folding and function by TRiC/CCT chaperonin. PLoS Biol 2014; 12:e1001844. [PMID: 24756126 PMCID: PMC3995649 DOI: 10.1371/journal.pbio.1001844] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 03/17/2014] [Indexed: 02/06/2023] Open
Abstract
Levels, folding, and function of the infamous cancer and inflammatory disease-related signaling molecule Stat3 are regulated by interaction with the chaperonin TRiC; manipulation of this interaction is a therapeutic avenue for exploration. Signal transducer and activator of transcription 3 (Stat3) transduces signals of many peptide hormones from the cell surface to the nucleus and functions as an oncoprotein in many types of cancers, yet little is known about how it achieves its native folded state within the cell. Here we show that Stat3 is a novel substrate of the ring-shaped hetero-oligomeric eukaryotic chaperonin, TRiC/CCT, which contributes to its biosynthesis and activity in vitro and in vivo. TRiC binding to Stat3 was mediated, at least in part, by TRiC subunit CCT3. Stat3 binding to TRiC mapped predominantly to the β-strand rich, DNA-binding domain of Stat3. Notably, enhancing Stat3 binding to TRiC by engineering an additional TRiC-binding domain from the von Hippel-Lindau protein (vTBD), at the N-terminus of Stat3, further increased its affinity for TRiC as well as its function, as determined by Stat3's ability to bind to its phosphotyrosyl-peptide ligand, an interaction critical for Stat3 activation. Thus, Stat3 levels and function are regulated by TRiC and can be modulated by manipulating its interaction with TRiC. Stat3 is a multidomain transcription factor that contributes to many cellular functions by transmitting signals for over 40 peptide hormones from the cell surface to the nucleus. Understanding how multidomain proteins achieve their fully folded and functional state is of substantial biological interest. As Stat3 signaling is up-regulated in many pathological conditions, including cancer and inflammatory diseases, insight into what controls its folding may be useful for the identification of vulnerabilities that can be therapeutically exploited. We demonstrate that the major protein-folding machine or chaperonin within eukaryotic cells, TRiC/CCT, is required for Stat3 to fold during its synthesis and for Stat3 to be fully functional within the cell. We also find that TRiC can refold chemically denatured Stat3 and provide evidence that the CCT3 subunit of TRiC binds to the DNA-binding domain of Stat3. We also show that Stat3 activity is decreased by down-modulating levels of TRiC and can be increased by increasing Stat3's interaction with TRiC. TRiC therefore regulates both Stat3 protein levels and its function, making Stat3 modulation by manipulation of its interaction with TRiC a potential approach for the treatment of cancer and inflammatory diseases.
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Affiliation(s)
- Moses Kasembeli
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wilson Chun Yu Lau
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Soung-Hun Roh
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - T. Kris Eckols
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - Judith Frydman
- Department of Biology and the BioX Program, Stanford University, Stanford, California, United States of America
| | - Wah Chiu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - David J. Tweardy
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Cellular and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Genetic Interactions of STAT3 and Anticancer Drug Development. Cancers (Basel) 2014; 6:494-525. [PMID: 24662938 PMCID: PMC3980611 DOI: 10.3390/cancers6010494] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 02/18/2014] [Accepted: 02/20/2014] [Indexed: 12/18/2022] Open
Abstract
Signal transducer and activator of transcription 3 (STAT3) plays critical roles in tumorigenesis and malignant evolution and has been intensively studied as a therapeutic target for cancer. A number of STAT3 inhibitors have been evaluated for their antitumor activity in vitro and in vivo in experimental tumor models and several approved therapeutic agents have been reported to function as STAT3 inhibitors. Nevertheless, most STAT3 inhibitors have yet to be translated to clinical evaluation for cancer treatment, presumably because of pharmacokinetic, efficacy, and safety issues. In fact, a major cause of failure of anticancer drug development is lack of efficacy. Genetic interactions among various cancer-related pathways often provide redundant input from parallel and/or cooperative pathways that drives and maintains survival environments for cancer cells, leading to low efficacy of single-target agents. Exploiting genetic interactions of STAT3 with other cancer-related pathways may provide molecular insight into mechanisms of cancer resistance to pathway-targeted therapies and strategies for development of more effective anticancer agents and treatment regimens. This review focuses on functional regulation of STAT3 activity; possible interactions of the STAT3, RAS, epidermal growth factor receptor, and reduction-oxidation pathways; and molecular mechanisms that modulate therapeutic efficacies of STAT3 inhibitors.
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Domoszlai T, Martincuks A, Fahrenkamp D, Schmitz-Van de Leur H, Küster A, Müller-Newen G. Consequences of the disease-related L78R mutation for dimerization and activity of STAT3. J Cell Sci 2014; 127:1899-910. [DOI: 10.1242/jcs.137422] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
STAT3 (signal transducer and activator of transcription 3) is a transcription factor centrally involved in diverse processes including hematopoiesis, immunity and cancer progression. In response to cytokine stimulation STAT3 is activated through phosphorylation of a single tyrosine residue. The phosphorylated STAT3 dimers are stabilized by intermolecular SH2 domain/phosphotyrosine interactions. These activated dimers accumulate in the nucleus and bind to specific DNA sequences resulting in target gene expression. We analysed and compared the structural organizations of the unphosphorylated latent and phosphorylated activated STAT3 dimers using Förster resonance energy transfer (FRET) in fixed and living cells. The latent dimers are stabilized by homotypic interactions between the N-terminal domains. A somatic mutation (L78R) found in inflammatory hepatocellular adenomas (IHCA) which is located in the N-terminal domain of STAT3 disturbs latent dimer formation. Applying intramolecular FRET we verify a functional role of the SH2 domain in latent dimer formation suggesting the parallel orientation of the protomers in the latent STAT3 dimer similar to activated STAT3 dimers but in contrast to the latent dimers of STAT1 and STAT5. Our findings reveal unique structural characteristics of STAT3 within the STAT family and contribute to the understanding of the L78R mutation found in IHCA.
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Xu Y, Shi Y, Yuan Q, Liu X, Yan B, Chen L, Tao Y, Cao Y. Epstein-Barr Virus encoded LMP1 regulates cyclin D1 promoter activity by nuclear EGFR and STAT3 in CNE1 cells. J Exp Clin Cancer Res 2013; 32:90. [PMID: 24499623 PMCID: PMC3843577 DOI: 10.1186/1756-9966-32-90] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 11/12/2013] [Indexed: 11/21/2022] Open
Abstract
The principal Epstein–Barr virus (EBV) oncoprotein, latent membrane protein 1 (LMP1) is strongly associated with nasopharyngeal carcinoma (NPC), a prevalent cancer in China. The epidermal growth factor receptor (EGFR) is important in carcinogenesis, as it is a ubiquitously expressed receptor tyrosine kinase. Signal transducer and activator of transcription 3 (STAT3) is a master transcriptional regulator in proliferation and apoptosis. Our previous study demonstrated that the nuclear EGFR could bind to the cyclin D1 promoter directly in the presence of LMP1, and the correlation between EGFR and STAT3 in NPC remains to be further explored. Here, we have shown that the interaction of EGFR and STAT3 increased in the nucleus in the presence of LMP1. LMP1 promoted both EGFR and STAT3 binding to the promoter region of cyclin D1, in turn, enhancing the promoter activity of cyclin D1. Furthermore, we demonstrated that both transcriptional activity and mRNA levels of cyclin D1 were decreased by small molecule interference of EGFR and STAT3 activity. These findings may provide a novel linkage between the EGFR and STAT3 signaling pathways and the activation of cyclin D1 by LMP1 in the carcinogenesis of NPC.
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Affiliation(s)
| | | | | | | | | | | | - Yongguang Tao
- Cancer Research Institute, Central South University, Changsha, Hunan 410078, China.
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Messenger SA, Moreau JM, Ciriello J. Effect of chronic intermittent hypoxia on leptin and leptin receptor protein expression in the carotid body. Brain Res 2013; 1513:51-60. [DOI: 10.1016/j.brainres.2013.03.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/18/2013] [Accepted: 03/20/2013] [Indexed: 01/20/2023]
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Elsarraj HS, Hong Y, Valdez K, Carletti M, Salah SM, Raimo M, Taverna D, Prochasson P, Bharadwaj U, Tweardy DJ, Christenson LK, Behbod F. A novel role of microRNA146b in promoting mammary alveolar progenitor cell maintenance. J Cell Sci 2013; 126:2446-58. [PMID: 23572509 DOI: 10.1242/jcs.119214] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In this report, we have shown that miR146b promotes the maintenance of pregnancy-derived mammary luminal alveolar progenitors. MiR146b expression was significantly higher in the mammary glands of pregnant and lactating mice than in virgin mice. Furthermore, miR146b levels were significantly higher in mouse mammary glands exposed to the sex hormones, estrogen and progesterone, compared with those of untreated control animals. Pregnancy-derived primary mouse mammary epithelial cells in which miR146b was knocked down showed a significant reduction in the number of hollow acinar organoid structures formed on three-dimensional Matrigel and in β-casein expression. This demonstrates that miR146b promotes the maintenance of pregnancy-derived mammary luminal alveolar progenitors. It has been shown that mouse mammary luminal progenitors give rise to hollow organoid structures, whereas solid organoid structures are derived from stem cells. Among several miR146b targets, miR146b knockdown resulted in preferential STAT3β overexpression. In the primary mouse mammary epithelial cells, overexpression of STAT3β isoform caused mammary epithelial cell death and a significant reduction in β-casein mRNA expression. Therefore, we conclude that during pregnancy miR146b is involved in luminal alveolar progenitor cell maintenance, at least partially, by regulating STAT3β.
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Affiliation(s)
- Hanan S Elsarraj
- Department of Pathology and Laboratory Medicine, The University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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Selective STAT3-α or -β expression reveals spliceform-specific phosphorylation kinetics, nuclear retention and distinct gene expression outcomes. Biochem J 2012; 447:125-36. [PMID: 22799634 PMCID: PMC3441131 DOI: 10.1042/bj20120941] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Phosphorylation of STAT3 (signal transducer and activator of transcription 3) is critical for its nuclear import and transcriptional activity. Although a shorter STAT3β spliceform was initially described as a negative regulator of STAT3α, gene knockout studies have revealed that both forms play critical roles. We have expressed STAT3α and STAT3β at comparable levels to facilitate a direct comparison of their functional effects, and have shown their different cytokine-stimulated kinetics of phosphorylation and nuclear translocation. Notably, the sustained nuclear translocation and phosphorylation of STAT3β following cytokine exposure contrasted with a transient nuclear translocation and phosphorylation of STAT3α. Importantly, co-expression of the spliceforms revealed that STAT3β enhanced and prolonged the phosphorylation and nuclear retention of STAT3α, but a STAT3β R609L mutant, with a disrupted SH2 (Src homology 2) domain, was not tyrosine phosphorylated following cytokine stimulation and could not cross-regulate STAT3α. The physiological importance of prolonged phosphorylation and nuclear retention was indicated by transcriptome profiling of STAT3−/− cells expressing either STAT3α or STAT3β, revealing the complexity of genes that are up- and down-regulated by the STAT3 spliceforms, including a distinct set of STAT3β-specific genes regulated under basal conditions and after cytokine stimulation. These results highlight STAT3β as a significant transcriptional regulator in its own right, with additional actions to cross-regulate STAT3α phosphorylation and nuclear retention after cytokine stimulation.
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Selective small molecule Stat3 inhibitor reduces breast cancer tumor-initiating cells and improves recurrence free survival in a human-xenograft model. PLoS One 2012; 7:e30207. [PMID: 22879872 PMCID: PMC3412855 DOI: 10.1371/journal.pone.0030207] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 12/12/2011] [Indexed: 01/05/2023] Open
Abstract
Metastasis and disease relapse are hypothesized to result from tumor initiating cells (TICs). Previously, we have defined a CD44+/CD24−/low mammosphere-forming tumorigenic 493-gene signature in breast cancer. Stat3 was identified as a critical node in self-renewal based on an ongoing lentiviral shRNA screen being conducted in two breast cancer cell lines SUM159 and BT549. In corroborating work, targeting the SH2 domain of Stat3 with a novel small molecule decreased the percentage of cells expressing TIC markers (CD44+/CD24−/low and ALDH+) and mammosphere formation in p-Stat3 overexpressing human breast cancer xenografts in SCID-beige mice. Importantly, we observed a four-fold improvement in the 30-day recurrence-free survival relative to docetaxel alone with the addition of the Stat3 inhibitor in the chemoresistant tumor model. Thus, these findings provide a strong impetus for the development of selective Stat3 inhibitors in order to improve survival in patients with p-Stat3 overexpressing tumors.
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Influence of conformationally restricted pyrimidines on the activity of 10–23 DNAzymes. Bioorg Med Chem 2012; 20:2581-6. [DOI: 10.1016/j.bmc.2012.02.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 02/14/2012] [Accepted: 02/20/2012] [Indexed: 01/05/2023]
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38
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Antitumorigenic potential of STAT3 alternative splicing modulation. Proc Natl Acad Sci U S A 2011; 108:17779-84. [PMID: 22006329 DOI: 10.1073/pnas.1108482108] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Signal transducer and activator of transcription 3 (STAT3) plays a central role in the activation of multiple oncogenic pathways. Splicing variant STAT3β uses an alternative acceptor site within exon 23 that leads to a truncated isoform lacking the C-terminal transactivation domain. Depending on the context, STAT3β can act as a dominant-negative regulator of transcription and promote apoptosis. We show that modified antisense oligonucleotides targeted to a splicing enhancer that regulates STAT3 exon 23 alternative splicing specifically promote a shift of expression from STAT3α to STAT3β. Induction of endogenous STAT3β leads to apoptosis and cell-cycle arrest in cell lines with persistent STAT3 tyrosine phosphorylation compared with total STAT3 knockdown obtained by forced splicing-dependent nonsense-mediated decay (FSD-NMD). Comparison of the molecular effects of splicing redirection to STAT3 knockdown reveals a unique STAT3β signature, with a down-regulation of specific targets (including lens epithelium-derived growth factor, p300/CBP-associated factor, CyclinC, peroxisomal biogenesis factor 1, and STAT1β) distinct from canonical STAT3 targets typically associated with total STAT3 knockdown. Furthermore, similar in vivo redirection of STAT3 alternative splicing leads to tumor regression in a xenograft cancer model, demonstrating how pharmacological manipulation of a single key splicing event can manifest powerful antitumorigenic properties and validating endogenous splicing reprogramming as an effective cancer therapeutic approach.
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Cimica V, Chen HC, Iyer JK, Reich NC. Dynamics of the STAT3 transcription factor: nuclear import dependent on Ran and importin-β1. PLoS One 2011; 6:e20188. [PMID: 21625522 PMCID: PMC3098288 DOI: 10.1371/journal.pone.0020188] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Accepted: 04/27/2011] [Indexed: 01/05/2023] Open
Abstract
The signal transducer and activator of transcription-3 (STAT3) induces transcription of genes that control differentiation, inflammation, proliferation, and tumor cell invasion. Cytokines such as interleukin-6 and interferon stimulate the specific tyrosine phosphorylation of STAT3, which confers its ability to bind consensus DNA targets. In addition, unphosphorylated STAT3 has been demonstrated to induce specific gene expression. STAT3 must gain entrance to the nucleus to impact transcription, however access to the nucleus is a tightly regulated process. Because nuclear trafficking is critical to the function of STAT3, we investigated the molecular mechanisms by which STAT3 is imported to the nucleus. Live cell imaging techniques were used with STAT3 tagged with green fluorescence protein (GFP) or photoactivatable GFP to follow the cellular dynamics of both unphosphorylated and tyrosine phosphorylated forms. Cytokine activation did not alter the rate of STAT3 nuclear import or nuclear export. In addition, Förster resonance energy transfer experiments revealed homomeric interaction of unphosphorylated STAT3 dependent on its amino terminus, but this dimerization is not necessary for its nuclear import. Previous work demonstrated the adapter importin-α3 binds to STAT3 and is required for nuclear import. To determine whether STAT3 nuclear import is mediated by the importin-α/importin-β1 heterodimer, the effects of siRNA to importin-β1 were evaluated. Results indicate STAT3 nuclear import is dependent on the function of importin-β1. Since the Ran GTPase is necessary to bind importin-β1 in the nucleus for release of importin-α-cargo, the effect of a GTPase deficient mutant of Ran was tested. Expression of the Ran interfering mutant inhibited STAT3 nuclear import. This study defines importin-α/importin-β1/Ran as the molecular mechanism by which STAT3 traffics to the nucleus.
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Affiliation(s)
- Velasco Cimica
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Hui-Chen Chen
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Janaki K. Iyer
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
| | - Nancy C. Reich
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York, United States of America
- * E-mail:
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Hannigan A, Qureshi AM, Nixon C, Tsimbouri PM, Jones S, Philbey AW, Wilson JB. Lymphocyte deficiency limits Epstein-Barr virus latent membrane protein 1 induced chronic inflammation and carcinogenic pathology in vivo. Mol Cancer 2011; 10:11. [PMID: 21291541 PMCID: PMC3041781 DOI: 10.1186/1476-4598-10-11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 02/03/2011] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The importance of the malignant cell environment to its growth and survival is becoming increasingly apparent, with dynamic cross talk between the neoplastic cell, the leukocyte infiltrate and the stroma. Most cancers are accompanied by leukocyte infiltration which, contrary to an anticipated immuno-protective role, could be contributing to tumour development and cancer progression. Epstein-Barr virus (EBV) associated cancers, including nasopharyngeal carcinoma and Hodgkin's Disease, show a considerable leukocyte infiltration which surrounds the neoplastic cells, raising the questions as to what role these cells play in either restricting or supporting the tumour and what draws the cells into the tumour. In order to begin to address this we have studied a transgenic model of multistage carcinogenesis with epithelial expression of the EBV primary oncoprotein, latent membrane protein 1 (LMP1). LMP1 is expressed particularly in the skin, which develops a hyperplastic pathology soon after birth. RESULTS The pathology advances with time leading to erosive dermatitis which is inflamed with a mixed infiltrate involving activated CD8+ T-cells, CD4+ T-cells including CD4+/CD25+/FoxP3+ Treg cells, mast cells and neutrophils. Also significant dermal deposition of immunoglobulin-G (IgG) is observed as the pathology advances. Along with NF-kappaB activation, STAT3, a central factor in inflammation regulation, is activated in the transgenic tissue. Several inflammatory factors are subsequently upregulated, notably CD30 and its ligand CD153, also leukocyte trafficking factors including CXCL10, CXCL13, L-selectin and TGFβ1, and inflammatory cytokines including IL-1β, IL-3 and the murine IL-8 analogues CXCL1, CXCL2 and CXCL5-6, amongst others. The crucial role of mature T- and/or B-lymphocytes in the advancing pathology is demonstrated by their elimination, which precludes mast cell infiltration and limits the pathology to an early, benign stage. CONCLUSIONS LMP1 can lead to the activation of several key factors mediating proliferation, angiogenesis and inflammation in vivo. With the initiation of an inflammatory programme, leukocyte recruitment follows which then itself contributes to the progressing pathology in these transgenic mice, with a pivotal role for B-and/or T-cells in the process. The model suggests a basis for the leukocyte infiltrate observed in EBV-associated cancer and its supporting role, as well as potential points for therapeutic intervention.
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Affiliation(s)
- Adele Hannigan
- College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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Signal transducer and activator of transcription 3β in pancreatic cancer. Open Life Sci 2010. [DOI: 10.2478/s11535-010-0029-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractSignal transducer and activator of transcription 3 (STAT3) has four isoforms: α, β, γ and δ. STAT3α and STAT3β are the transcriptionally active isoforms, while STAT3γ and STAT3δ are the products of STAT3 proteolytic degradation. STAT3 plays an important role in angiogenesis, cell proliferation and apoptosis. High levels of STAT3β in blood cells from acute leukaemia patients have been reported, suggesting that STAT3β may play an important role in cancerogenesis. Fourteen pancreatic cancer patients and six chronic pancreatitis patients were included in this pilot study. Levels of STAT3 isoforms from samples with pancreatic cancer and in adjacent histologically-normal pancreatic tissue were analysed. Pancreas from chronic pancreatitis patients served as a non-neoplastic tissue. Western-blot analysis of STAT3 proteins with the use of anti-STAT3 antibodies was performed. STAT3α and STAT3β isoforms in both cancerous and in adjacent normal tissues were found in 10 of 14. In chronic pancreatitis patients, only STAT3α and STAT3δ were detected. STAT3β was absent in pancreas from chronic pancreatitis patients, in contrast to pancreatic cancer patients. The presence of STAT3β in pancreatic cancer and in adjacent histologically-normal tissues, but not in inflamed tissues suggests that STAT3β may play a key role in cancer development.
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Benekli M, Baumann H, Wetzler M. Targeting signal transducer and activator of transcription signaling pathway in leukemias. J Clin Oncol 2009; 27:4422-32. [PMID: 19667270 DOI: 10.1200/jco.2008.21.3264] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Signal transducer and activator of transcription (STAT) proteins comprise a seven-member family of latent cytoplasmic transcription factors that are activated through tyrosine phosphorylation by a variety of cytokines and growth factors. Aberrant activation of STATs accompanies malignant cellular transformation with resultant leukemogenesis. Constitutive activation of STATs has been demonstrated in various leukemias. A better understanding of the mechanisms of dysregulation of the STAT pathway and understanding of the cause and effect relationship in leukemogenesis may serve as a basis for designing novel therapeutic strategies directed against STATs. Mechanisms of STAT activation, the potential role of STAT signaling in leukemogenesis, and recent advances in drug discovery targeting the STAT pathway are the focus of this review.
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Affiliation(s)
- Mustafa Benekli
- Department of Medical Oncology, Gazi University Faculty of Medicine, Ankara, Turkey
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Xu X, Kasembeli MM, Jiang X, Tweardy BJ, Tweardy DJ. Chemical probes that competitively and selectively inhibit Stat3 activation. PLoS One 2009; 4:e4783. [PMID: 19274102 PMCID: PMC2653189 DOI: 10.1371/journal.pone.0004783] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Accepted: 01/12/2009] [Indexed: 01/27/2023] Open
Abstract
Signal transducer and activator of transcription (Stat) 3 is an oncogene constitutively activated in many cancer systems where it contributes to carcinogenesis. To develop chemical probes that selectively target Stat3, we virtually screened 920,000 small drug-like compounds by docking each into the peptide-binding pocket of the Stat3 SH2 domain, which consists of three sites—the pY-residue binding site, the +3 residue-binding site and a hydrophobic binding site, which served as a selectivity filter. Three compounds satisfied criteria of interaction analysis, competitively inhibited recombinant Stat3 binding to its immobilized pY-peptide ligand and inhibited IL-6-mediated tyrosine phosphorylation of Stat3. These compounds were used in a similarity screen of 2.47 million compounds, which identified 3 more compounds with similar activities. Examination of the 6 active compounds for the ability to inhibit IFN-γ-mediated Stat1 phosphorylation revealed that 5 of 6 were selective for Stat3. Molecular modeling of the SH2 domains of Stat3 and Stat1 bound to compound revealed that compound interaction with the hydrophobic binding site was the basis for selectivity. All 5 selective compounds inhibited nuclear-to-cytoplasmic translocation of Stat3, while 3 of 5 compounds induced apoptosis preferentially of breast cancer cell lines with constitutive Stat3 activation. Thus, virtual ligand screening of compound libraries that targeted the Stat3 pY-peptide binding pocket identified for the first time 3 lead compounds that competitively inhibited Stat3 binding to its pY-peptide ligand; these compounds were selective for Stat3 vs. Stat1 and induced apoptosis preferentially of breast cancer cells lines with constitutively activated Stat3.
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Affiliation(s)
- Xuejun Xu
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - Moses M. Kasembeli
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - Xueqing Jiang
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - Benjamin J. Tweardy
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
| | - David J. Tweardy
- Section of Infectious Diseases, Department of Medicine, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Wagner T, Kraeussling M, Fedorov L, Reiss C, Kneitz B, Schartl M. STAT3 and SMAD1 Signaling in Medaka Embryonic Stem-Like Cells and Blastula Embryos. Stem Cells Dev 2009; 18:151-60. [DOI: 10.1089/scd.2007.0262] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- T.U. Wagner
- University of Wurzburg, Physiological Chemistry I, Wurzburg, Germany
| | - M. Kraeussling
- University of Wurzburg, Physiological Chemistry I, Wurzburg, Germany
| | - L.M. Fedorov
- University of Wurzburg, Physiological Chemistry I, Wurzburg, Germany
| | - C. Reiss
- University of Wurzburg, Physiological Chemistry I, Wurzburg, Germany
| | - B. Kneitz
- Department of Urology and Paediatric Urology, Bavarian Julius Maximilians University Medical School, Wurzburg, Germany
| | - M. Schartl
- University of Wurzburg, Physiological Chemistry I, Wurzburg, Germany
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Groner B, Lucks P, Borghouts C. The function of Stat3 in tumor cells and their microenvironment. Semin Cell Dev Biol 2008; 19:341-50. [PMID: 18621135 DOI: 10.1016/j.semcdb.2008.06.005] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2008] [Revised: 06/06/2008] [Accepted: 06/17/2008] [Indexed: 12/13/2022]
Abstract
Stat3 was initially recognized as a transcription factor and mediates the nuclear action of many different cytokines and growth factors. In addition to its roles in normal cell function, the inappropriate activation of Stat3 in tumor cells has attracted the attention of tumor biologists and has led to the consideration of Stat3 as a drug target. The induction of Stat3 activity under physiological circumstances is transient and many different levels of activation and deactivation have been defined. In addition to kinases and phosphatases, the SOCS proteins and the PIAS proteins have been recognized as negatively regulating components, which fine-tune the extent and the duration of Stat3 function. Its nuclear cytoplasmic shuttling is exquisitely regulated and adds to the complexity of Stat3 action. Newly discovered associations with cytoplasmic molecules suggest functions outside the conventional transcriptional regulation context. High molecular weight transcription complexes suggest that Stat3 might assume roles in transcriptional induction as well as in transcriptional suppression. The aberrant activation in tumor cells and the central function of Stat3 in the communication between cells of the immune system and tumor cells are of great interest for translational research projects and innovative drug development.
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Affiliation(s)
- Bernd Groner
- Georg-Speyer-Haus, Institute for Biomedical Research, Paul-Ehrlich-Strasse 42-44, D-60596 Frankfurt am Main, Germany.
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Beysen D, Moumné L, Veitia R, Peters H, Leroy BP, De Paepe A, De Baere E. Missense mutations in the forkhead domain of FOXL2 lead to subcellular mislocalization, protein aggregation and impaired transactivation. Hum Mol Genet 2008; 17:2030-8. [PMID: 18372316 DOI: 10.1093/hmg/ddn100] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mutations of the FOXL2 gene have been shown to cause blepharophimosis syndrome (BPES), characterized by an eyelid malformation associated with premature ovarian failure or not. Recently, polyalanine expansions and truncating FOXL2 mutations have been shown to lead to protein mislocalization, aggregation and altered transactivation. Here, we study the molecular consequences of 17 naturally occurring FOXL2 missense mutations. Most of them map to the conserved DNA-binding forkhead domain (FHD). The subcellular localization and aggregation pattern of the mutant FOXL2 proteins in COS-7 cells was variable and ranged from a diffuse nuclear distribution like the wild-type to extensive nuclear aggregation often in combination with cytoplasmic mislocalization and aggregation. We also studied the transactivation capacity of the mutants in FOXL2 expressing granulosa-like cells (KGN). Several mutants led to a loss-of-function, while others are suspected to induce a dominant negative effect. Interestingly, one mutant that is located outside the FHD (S217F), appeared to be hypermorphic and had no effect on intracellular protein distribution. This mutation gives rise to a mild BPES phenotype. In general, missense mutations located in the FHD lead to classical BPES and cannot be correlated with expression of the ovarian phenotype. However, a potential predictive value of localization and transactivation assays in the making of genotype-phenotype correlations is proposed. This is the first study to demonstrate that a significant number of missense mutations in the FHD of FOXL2 lead to mislocalization, protein aggregation and altered transactivation, and to provide insights into the pathogenesis associated with missense mutations of FOXL2 in human disease.
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Affiliation(s)
- Diane Beysen
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
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