1
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Zhang P, Zhang W, Wang X, Li L, Lin Y, Wu N, Mao R, Lin J, Kang M, Ding C. BCLAF1 drives esophageal squamous cell carcinoma progression through regulation of YTHDF2-dependent SIX1 mRNA degradation. Cancer Lett 2024; 591:216874. [PMID: 38636894 DOI: 10.1016/j.canlet.2024.216874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 04/01/2024] [Accepted: 04/07/2024] [Indexed: 04/20/2024]
Abstract
Esophageal cancer ranks among the most prevalent malignant tumors, and esophageal squamous cell carcinoma (ESCC) constitutes its predominant histological form. Despite its impact, a thorough insight into the molecular intricacies of ESCC's development is still incomplete, which hampers the advancement of targeted molecular diagnostics and treatments. Recently, B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) has come under investigation for its potential involvement in tumor biology, yet its specific role and mechanism in ESCC remain unclear. In this study, we observed a marked increase in BCLAF1 expression in ESCC tissues, correlating with advanced tumor stages and inferior patient outcomes. Our comprehensive in vitro and in vivo studies show that BCLAF1 augments glycolytic activity and the proliferation, invasion, and spread of ESCC cells. By employing mass spectrometry, we identified YTHDF2 as a key protein interacting with BCLAF1 in ESCC, with further validation provided by colocalization, co-immunoprecipitation, and GST pull-down assay. Further investigations involving MeRIP-seq and RIP-seq, alongside transcriptomic analysis, highlighted SIX1 mRNA as a molecule significantly upregulated and modified by N6-methyladenosine (m6A) in BCLAF1 overexpressing cells. BCLAF1 was found to reduce the tumor-suppressive activities of YTHDF2, and its effects on promoting glycolysis and cancer progression were shown to hinge on SIX1 expression. This research establishes that BCLAF1 fosters glycolysis and tumor progression in ESCC through the YTHDF2-SIX1 pathway in an m6A-specific manner, suggesting a potential target for future therapeutic intervention.
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Affiliation(s)
- Peipei Zhang
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Weiguang Zhang
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Xiaoqing Wang
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Lingling Li
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Institutes of Biomedical Sciences, Human Phenome Institute, Fudan University, Shanghai, 200433, China
| | - Ye Lin
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Ningzi Wu
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Renyan Mao
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Jihong Lin
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Mingqiang Kang
- Department of Thoracic Surgery, Fujian Medical University Union Hospital, Fuzhou, 350001, China; Department of Cardiothoracic Surgery, Affiliated Hospital of Putian University, Putian, 351100, China; Key Laboratory of Gastrointestinal Cancer (Fujian Medical University), Ministry of Education, Fuzhou, 350108, China.
| | - Chen Ding
- State Key Laboratory of Genetic Engineering and Collaborative Innovation Center for Genetics and Development, School of Life Sciences, Institutes of Biomedical Sciences, Human Phenome Institute, Fudan University, Shanghai, 200433, China.
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2
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Rafiq A, Aashaq S, Jan I, Ali M, Rakshan R, Bashir A, Haq E, Beigh MA. GSK3β phosphorylates Six1 transcription factor and regulates its APC/C Cdh1 mediated proteosomal degradation. Cell Signal 2024; 115:111030. [PMID: 38163577 DOI: 10.1016/j.cellsig.2023.111030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 12/19/2023] [Accepted: 12/29/2023] [Indexed: 01/03/2024]
Abstract
Sine oculis homeobox homolog 1 (Six1) is a developmentally important transcription factor that regulates cellular proliferation, apoptosis, and dissemination during embryogenesis. Six1 overexpression as reported in multiple cancers modulates expression of a repertoire of its target genes causing an increase in proliferation, metastasis and survival of cancer cells. Six1 exists as a cell cycle regulated nuclear phosphoprotein and its cellular turnover is regulated by APC/C (Anaphase promoting complex / Cyclosome) complex mediated proteolysis. However, the kinases that regulate Six1 proteolysis have not been identified and the mechanistic details that cause its overproduction in various cancers are lacking. Here, we report that Six1 is a physiological GSK3β substrate. GSK3β interacts with Six1 and phosphorylates it at Ser221 within the conserved consensus sequence in its carboxy terminus. Using pharmacological inhibition, siRNA mediated knockdown and protein overexpression of GSK3β; we show that GSK3β regulates Six1 protein stability. Pulse chase analysis of Six1 revealed that GSK3β regulates its ubiquitin proteolysis such that Six1 phosphomimicking mutant (Six1S221E) for Ser221 site had dramatically increased half-life than its phosphodeficient (Six1S221A) and wild type variants. Furthermore, we demonstrate that GSK3β rescues Six1 from APC dependent proteolysis by regulating its binding with APC/C co-activator protein Cdh1. Importantly, strong positive correlation exists between GSK3β and Six1 protein levels throughout the cell cycle and in multiple cancers indicating that GSK3β activation may in part contribute to Six1 overproduction in a subset of human cancers.
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Affiliation(s)
- Asma Rafiq
- Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India
| | - Sabreena Aashaq
- Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India; Department of Immunology and Molecular Medicine, SKIMS, Srinagar 190011, India
| | - Iqra Jan
- Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India
| | - Mahvish Ali
- Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India
| | - Rabia Rakshan
- Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India
| | - Asma Bashir
- Faculty of Biology, Fatima College of Health Sciences, Al-Raqaib 2, Ajman 3798, United Arab Emirates
| | - Ehtishamul Haq
- Department of Biotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India
| | - Mushtaq A Beigh
- Department of Nanotechnology, School of Biological Sciences, University of Kashmir-, Srinagar 190006, India.
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3
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Liu Y, Kong WY, Yu CF, Shao ZL, Lei QC, Deng YF, Cai GX, Zhuang XF, Sun WS, Wu SG, Wang R, Chen X, Chen GX, Huang HB, Liao YN. SNS-023 sensitizes hepatocellular carcinoma to sorafenib by inducing degradation of cancer drivers SIX1 and RPS16. Acta Pharmacol Sin 2023; 44:853-864. [PMID: 36261513 PMCID: PMC10043269 DOI: 10.1038/s41401-022-01003-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 09/20/2022] [Indexed: 11/08/2022] Open
Abstract
Hepatocellular carcinoma (HCC) remains challenging due to the lack of efficient therapy. Promoting degradation of certain cancer drivers has become an innovative therapy. The nuclear transcription factor sine oculis homeobox 1 (SIX1) is a key driver for the progression of HCC. Here, we explored the molecular mechanisms of ubiquitination of SIX1 and whether targeting SIX1 degradation might represent a potential strategy for HCC therapy. Through detecting the ubiquitination level of SIX1 in clinical HCC tissues and analyzing TCGA and GEPIA databases, we found that ubiquitin specific peptidase 1 (USP1), a deubiquitinating enzyme, contributed to the lower ubiquitination and high protein level of SIX1 in HCC tissues. In HepG2 and Hep3B cells, activation of EGFR-AKT signaling pathway promoted the expression of USP1 and the stability of its substrates, including SIX1 and ribosomal protein S16 (RPS16). In contrast, suppression of EGFR with gefitinib or knockdown of USP1 restrained EGF-elevated levels of SIX1 and RPS16. We further revealed that SNS-023 (formerly known as BMS-387032) induced degradation of SIX1 and RPS16, whereas this process was reversed by reactivation of EGFR-AKT pathway or overexpression of USP1. Consequently, inactivation of the EGFR-AKT-USP1 axis with SNS-032 led to cell cycle arrest, apoptosis, and suppression of cell proliferation and migration in HCC. Moreover, we showed that sorafenib combined with SNS-032 or gefitinib synergistically inhibited the growth of Hep3B xenografts in vivo. Overall, we identify that both SIX1 and RPS16 are crucial substrates for the EGFR-AKT-USP1 axis-driven growth of HCC, suggesting a potential anti-HCC strategy from a novel perspective.
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Affiliation(s)
- Yuan Liu
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Wei-Yao Kong
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Cui-Fu Yu
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Zhen-Long Shao
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Qiu-Cheng Lei
- Department of Hepatopancreatic Surgery, The First People's Hospital of Foshan, Foshan, 528000, China
| | - Yuan-Fei Deng
- Department of Pathology, The First People's Hospital of Foshan, Foshan, 528000, China
| | - Geng-Xi Cai
- Department of Breast Surgery, The First People's Hospital of Foshan, Foshan, 528000, China
| | - Xue-Fen Zhuang
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Wen-Shuang Sun
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China
| | - Shi-Gang Wu
- Department of Pathology, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China
| | - Rong Wang
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China
| | - Xiang Chen
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China
| | - Guo-Xing Chen
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China.
| | - Hong-Biao Huang
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China.
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China.
| | - Yu-Ning Liao
- Department of General Surgery, The Sixth Affiliated Hospital of Guangzhou Medical University, Qingyuan People's Hospital, Qingyuan, 511500, China.
- Affiliated Cancer Hospital & Institute of Guangzhou Medical University, Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, 511436, China.
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4
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Rafiq A, Aashaq S, Jan I, Beigh MA. SIX1 transcription factor: A review of cellular functions and regulatory dynamics. Int J Biol Macromol 2021; 193:1151-1164. [PMID: 34742853 DOI: 10.1016/j.ijbiomac.2021.10.133] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 10/17/2021] [Accepted: 10/18/2021] [Indexed: 10/19/2022]
Abstract
Sine Oculis Homeobox 1 (SIX1) is a member of homeobox transcription factor family having pivotal roles in organismal development and differentiation. This protein functionally acts to regulate the expression of different proteins that are involved in organ development during embryogenesis and in disorders like cancer. Aberrant expression of this homeoprotein has therefore been reported in multiple pathological complexities like hearing impairment and renal anomalies during development and tumorigenesis in adult life. Most of the cellular effects mediated by it are mostly due to its role as a transcription factor. This review presents a concise narrative of its structure, interaction partners and cellular functions vis a vis its role in cancer. We thoroughly discuss the reported molecular mechanisms that govern its function in cellular milieu. Its post-translational regulation by phosphorylation and ubiquitination are also discussed with an emphasis on yet to be explored mechanistic insights regulating its molecular dynamics to fully comprehend its role in development and disease.
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Affiliation(s)
- Asma Rafiq
- Department of Nanotechnology, University of Kashmir, Hazratbal Campus, Srinagar JK-190006, India
| | - Sabreena Aashaq
- Department of Immunology and Molecular Medicine, Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar JK-190011, India
| | - Iqra Jan
- Department of Nanotechnology, University of Kashmir, Hazratbal Campus, Srinagar JK-190006, India
| | - Mushtaq A Beigh
- Department of Nanotechnology, University of Kashmir, Hazratbal Campus, Srinagar JK-190006, India.
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5
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Zhu G, Liu Y, Zhao L, Lin Z, Piao Y. The Significance of SIX1 as a Prognostic Biomarker for Survival Outcome in Various Cancer Patients: A Systematic Review and Meta-Analysis. Front Oncol 2021; 11:622331. [PMID: 34745930 PMCID: PMC8567106 DOI: 10.3389/fonc.2021.622331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 09/30/2021] [Indexed: 11/17/2022] Open
Abstract
Sine Oculis Homeobox Homolog 1 (SIX1) is reported to promote cancer initiation and progression in many preclinical models and is demonstrated in human cancer tissues. However, the correlation between SIX1 and cancer patients’ prognosis has not yet been systematically evaluated. Therefore, we performed a systematic review and meta-analysis in various human cancer types and extracted some data from TCGA datasets for further verification and perfection. We constructed 27 studies and estimated the association between SIX1 expression in various cancer patients’ overall survival and verified with TCGA datasets. Twenty-seven studies with 4899 patients are include in the analysis of overall, and disease-free survival, most of them were retrospective. The pooled hazard ratios (HRs) for overall and disease-free survival in high SIX1 expression patients were 1.54 (95% CI: 1.32-1.80, P<0.00001) and 1.83 (95% CI: 1.31-2.55, P=0.0004) respectively. On subgroup analysis classified in cancer type, high SIX1 expression was associated with poor overall survival in patients with hepatocellular carcinoma (HR 1.50; 95% CI: 1.17-1.93, P =0.001), breast cancer (HR 1.31; 95% CI: 1.10-1.55, P =0.002) and esophageal squamous cell carcinoma (HR 1.89; 95% CI: 1.42-2.52, P<0.0001). Next, we utilized TCGA online datasets, and the consistent results were verified in various cancer types. SIX1 expression indicated its potential to serve as a cancer biomarker and deliver prognostic information in various cancer patients. More works still need to improve the understandings of SIX1 expression and prognosis in different cancer types.
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Affiliation(s)
- Guang Zhu
- Guangdong Provincial Education Department Key Laboratory of Nano-Immunoregulation Tumour Microenvironment, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.,Tumor Research Center, Medical School of Yanbian University, Key Laboratory of Pathobiology of High Frequency Oncology in Ethnic Minority Areas (Yanbian University), State Ethnic Affairs Commission, Yanji, China
| | - Ying Liu
- Tumor Research Center, Medical School of Yanbian University, Key Laboratory of Pathobiology of High Frequency Oncology in Ethnic Minority Areas (Yanbian University), State Ethnic Affairs Commission, Yanji, China
| | - Lei Zhao
- Tumor Research Center, Medical School of Yanbian University, Key Laboratory of Pathobiology of High Frequency Oncology in Ethnic Minority Areas (Yanbian University), State Ethnic Affairs Commission, Yanji, China
| | - Zhenhua Lin
- Tumor Research Center, Medical School of Yanbian University, Key Laboratory of Pathobiology of High Frequency Oncology in Ethnic Minority Areas (Yanbian University), State Ethnic Affairs Commission, Yanji, China.,Key Laboratory of Science and Technology Department of Jilin Province, Key Laboratory of Changbai Mountain Natural Medicine of Ministry of Education, Yanbian University, Yanji, China
| | - Yingshi Piao
- Tumor Research Center, Medical School of Yanbian University, Key Laboratory of Pathobiology of High Frequency Oncology in Ethnic Minority Areas (Yanbian University), State Ethnic Affairs Commission, Yanji, China.,Key Laboratory of Science and Technology Department of Jilin Province, Key Laboratory of Changbai Mountain Natural Medicine of Ministry of Education, Yanbian University, Yanji, China
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6
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Liao Y, Liu Y, Shao Z, Xia X, Deng Y, Cai J, Yao L, He J, Yu C, Hu T, Sun W, Liu F, Tang D, Liu J, Huang H. A new role of GRP75-USP1-SIX1 protein complex in driving prostate cancer progression and castration resistance. Oncogene 2021; 40:4291-4306. [PMID: 34079090 DOI: 10.1038/s41388-021-01851-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 05/05/2021] [Accepted: 05/20/2021] [Indexed: 01/23/2023]
Abstract
Prostate cancer (PC) is the second most common cancer with limited treatment option in males. Although the reactivation of embryonic signals in adult cells is one of the characteristics of cancer, the underlying protein degradation mechanism remains elusive. Here, we show that the molecular chaperone GRP75 is a key player in PC cells by maintaining the protein stability of SIX1, a transcription factor for embryonic development. Mechanistically, GRP75 provides a platform to recruit the deubiquitinating enzyme USP1 to inhibit K48-linked polyubiquitination of SIX1. Structurally, the C-terminus of GRP75 (433-679 aa) contains a peptide binding domain, which is required for the formation of GRP75-USP1-SIX1 protein complex. Functionally, pharmacological or genetic inhibition of the GRP75-USP1-SIX1 protein complex suppresses tumor growth and overcomes the castration resistance of PC cells in vitro and in xenograft mouse models. Clinically, the protein expression of SIX1 in PC tumor tissues is positively correlated with the expression of GRP75 and USP1. These new findings not only enhance our understanding of the protein degradation mechanism, but also may provide a potential way to enhance the anti-cancer activity of androgen suppression therapy.
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Affiliation(s)
- Yuning Liao
- Affiliated Cancer Hospital & institute of Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Yuan Liu
- Affiliated Cancer Hospital & institute of Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Zhenlong Shao
- Affiliated Cancer Hospital & institute of Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Xiaohong Xia
- Affiliated Cancer Hospital & institute of Guangzhou Medical University, Guangzhou, Guangdong, China.,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Yuanfei Deng
- Department of Pathology, First People's Hospital of Foshan, Foshan, Guangdong, China
| | - Jianyu Cai
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Leyi Yao
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Jinchan He
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Cuifu Yu
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Tumei Hu
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Wenshuang Sun
- Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Fang Liu
- Department of Pathology, First People's Hospital of Foshan, Foshan, Guangdong, China
| | - Daolin Tang
- Department of Surgery, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jinbao Liu
- Affiliated Cancer Hospital & institute of Guangzhou Medical University, Guangzhou, Guangdong, China. .,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China.
| | - Hongbiao Huang
- Affiliated Cancer Hospital & institute of Guangzhou Medical University, Guangzhou, Guangdong, China. .,Guangzhou Municipal and Guangdong Provincial Key Laboratory of Protein Modification and Degradation, School of Basic Medical Sciences, Guangzhou Medical University, Guangzhou, Guangdong, China.
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7
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Chu Y, Jiang M, Wu N, Xu B, Li W, Liu H, Su S, Shi Y, Liu H, Gao X, Fu X, Chen D, Li X, Wang W, Liang J, Nie Y, Fan D. O-GlcNAcylation of SIX1 enhances its stability and promotes Hepatocellular Carcinoma Proliferation. Am J Cancer Res 2020; 10:9830-9842. [PMID: 32863962 PMCID: PMC7449927 DOI: 10.7150/thno.45161] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/17/2020] [Indexed: 12/14/2022] Open
Abstract
It is universally accepted that aberrant metabolism facilitates tumor growth. However, how cancer cells coordinate glucose metabolism and tumor proliferation is largely unknown. Sine oculis homeobox homolog 1 (SIX1) is a transcription factor that belongs to the SIX family and is believed to play an important role in the regulation of the Warburg effect in tumors. However, whether the role of SIX1 and the molecular mechanisms that regulate its activity are similar in hepatocellular carcinoma (HCC) still needs further investigation. Methods: Western blotting was performed to determine the levels of SIX1 and O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) in HCC tissues. Cell Counting Kit 8 (CCK8), colony formation and mouse tumor model assays were used to establish the role of SIX1 and O-GlcNAcylation in HCC processes. Mass spectrometry, immunoprecipitation and site-directed mutagenesis were performed to confirm the O-GlcNAcylation of SIX1. Results: Here, we demonstrated that SIX1, the key transcription factor regulating the Warburg effect in cancer, promotes HCC growth in vitro and in vivo. Furthermore, we revealed that SIX1 could also enhance the levels of a posttranslational modification called O-GlcNAcylation. Importantly, we found that SIX1 was also highly modified by O-GlcNAcylation and that O-GlcNAcylation inhibited the ubiquitination degradation of SIX1. In addition, site-directed mutagenesis at position 276 (T276A) decreased the O-GlcNAcylation level and reversed the protumor effect of SIX1. Conclusions: We conclude that O-GlcNAcylation of SIX1 enhances its stability and promotes HCC proliferation. Our findings illustrate a novel feedback loop of SIX1 and O-GlcNAcylation and show that O-GlcNAcylation of SIX1 is an important way to coordinate glucose metabolism and tumor progression.
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8
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Kimata Y. APC/C Ubiquitin Ligase: Coupling Cellular Differentiation to G1/G0 Phase in Multicellular Systems. Trends Cell Biol 2019; 29:591-603. [DOI: 10.1016/j.tcb.2019.03.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 12/27/2022]
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9
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Liu Z, Mar KB, Hanners NW, Perelman SS, Kanchwala M, Xing C, Schoggins JW, Alto NM. A NIK-SIX signalling axis controls inflammation by targeted silencing of non-canonical NF-κB. Nature 2019; 568:249-253. [PMID: 30894749 PMCID: PMC6812682 DOI: 10.1038/s41586-019-1041-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 02/18/2019] [Indexed: 12/31/2022]
Abstract
The non-canonical NF-κB signalling cascade is essential for lymphoid organogenesis, B cell maturation, osteoclast differentiation, and inflammation in mammals1,2; dysfunction of this system is associated with human diseases, including immunological disorders and cancer3-6. Although expression of NF-κB-inducing kinase (NIK, also known as MAP3K14) is the rate-limiting step in non-canonical NF-κB pathway activation2,7, the mechanisms by which transcriptional responses are regulated remain largely unknown. Here we show that the sine oculis homeobox (SIX) homologue family transcription factors SIX1 and SIX2 are integral components of the non-canonical NF-κB signalling cascade. The developmentally silenced SIX proteins are reactivated in differentiated macrophages by NIK-mediated suppression of the ubiquitin proteasome pathway. Consequently, SIX1 and SIX2 target a subset of inflammatory gene promoters and directly inhibit the trans-activation function of the transcription factors RELA and RELB in a negative feedback circuit. In support of a physiologically pivotal role for SIX proteins in host immunity, a human SIX1 transgene suppressed inflammation and promoted the recovery of mice from endotoxic shock. In addition, SIX1 and SIX2 protected RAS/P53-driven non-small-cell lung carcinomas from inflammatory cell death induced by SMAC-mimetic chemotherapeutic agents (small-molecule activators of the non-canonical NF-κB pathway). Our findings identify a NIK-SIX signalling axis that fine-tunes inflammatory gene expression programs under both physiological and pathological conditions.
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Affiliation(s)
- Zixu Liu
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Katrina B Mar
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Natasha W Hanners
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sofya S Perelman
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Mohammed Kanchwala
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Chao Xing
- Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - John W Schoggins
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Neal M Alto
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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10
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Curtis NL, Bolanos-Garcia VM. The Anaphase Promoting Complex/Cyclosome (APC/C): A Versatile E3 Ubiquitin Ligase. Subcell Biochem 2019; 93:539-623. [PMID: 31939164 DOI: 10.1007/978-3-030-28151-9_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
Abstract
In the present chapter we discuss the essential roles of the human E3 ubiquitin ligase Anaphase Promoting Complex/Cyclosome (APC/C) in mitosis as well as the emerging evidence of important APC/C roles in cellular processes beyond cell division control such as regulation of genomic integrity and cell differentiation of the nervous system. We consider the potential incipient role of APC/C dysregulation in the pathophysiology of the neurological disorder Alzheimer's disease (AD). We also discuss how certain Deoxyribonucleic Acid (DNA) and Ribonucleic Acid (RNA) viruses take control of the host's cell division regulatory system through harnessing APC/C ubiquitin ligase activity and hypothesise the plausible molecular mechanisms underpinning virus manipulation of the APC/C. We also examine how defects in the function of this multisubunit protein assembly drive abnormal cell proliferation and lastly argue the potential of APC/C as a promising therapeutic target for the development of innovative therapies for the treatment of chronic malignancies such as cancer.
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Affiliation(s)
- Natalie L Curtis
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, England, UK
| | - Victor M Bolanos-Garcia
- Faculty of Health and Life Sciences, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, England, UK.
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11
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Chu Y, Jiang M, Du F, Chen D, Ye T, Xu B, Li X, Wang W, Qiu Z, Liu H, Nie Y, Liang J, Fan D. miR-204-5p suppresses hepatocellular cancer proliferation by regulating homeoprotein SIX1 expression. FEBS Open Bio 2018; 8:189-200. [PMID: 29435409 PMCID: PMC5794460 DOI: 10.1002/2211-5463.12363] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 11/08/2017] [Accepted: 11/15/2017] [Indexed: 01/16/2023] Open
Abstract
Fewer than 30% of patients with hepatocellular carcinoma (HCC) are eligible to receive curative therapies, and so a better understanding of the molecular mechanisms of HCC is needed to identify potential therapeutic targets. The role of microRNA (miRNA) in modulating tumour progression has been demonstrated, and therapies targeting miRNA appear promising. miR‐204‐5p has been shown to function in numerous types of cancer, but its role in HCC remains unclear. In this study, we found that miR‐204‐5p expression was downregulated in cancerous HCC tissues compared to nontumour tissues. Kaplan–Meier survival curve analysis also showed that low expression of miR‐204‐5p predicted worse outcomes of HCC patients. In addition, miR‐204‐5p expression was significantly lower in HCC cell lines. The function of miR‐204‐5p was also assessed both in vitro and in vivo. We demonstrated that ectopic expression of miR‐204‐5p in HCC cell lines inhibited HCC cell proliferation and clonogenicity using CCK8, BrdU and colony‐forming assays, while the inhibition of miR‐204‐5p enhanced proliferation and clonogenicity. Further in vivo studies in mice further confirmed the proliferation capacity of miR‐204‐5p. We also identified sine oculis homeobox homologue 1 (SIX1) as a direct target of miR‐204‐5p and showed that it was inversely correlated with miR‐204‐5p in both human and mouse HCC tissues. Transfection of miR‐204‐5p mimics in BEL‐7404 cells blocked the cell cycle by inhibiting the expression of cyclin‐D1 and cyclin‐A1, cell cycle‐related factors regulated by SIX1. More importantly, overexpression of the 3′UTR mutant SIX1 but not the wild‐type SIX1 abolished the suppressive effect of miR‐204‐5p, and downregulated SIX1 in BEL‐7402 cells that transfected with miR‐204 inhibitors could partly block the inhibitory effect of miR‐204‐5p on proliferation. Thus, we have demonstrated that miR‐204‐5p suppresses HCC proliferation by directly regulating SIX1 and its downstream factors.
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Affiliation(s)
- Yi Chu
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Mingzuo Jiang
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Feng Du
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Di Chen
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Tao Ye
- State Key Laboratory of Military Stomatology National Clinical Research Center for Oral Diseases Shannxi key Laboratory of Oral Diseases School of Stomatology The Fourth Military Medical University Xi'an China
| | - Bing Xu
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Xiaowei Li
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Weijie Wang
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Zhaoyan Qiu
- Department of General Surgery the General Hospital of the people's Liberation Army Beijing China
| | - Haiming Liu
- College of Computer Science and Technology Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University Changchun China
| | - Yongzhan Nie
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Jie Liang
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
| | - Daiming Fan
- State Key Laboratory of Cancer Biology & Institute of Digestive Diseases Xijing Hospital The Fourth Military Medical University Xi'an China
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12
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Xin X, Li Y, Yang X. SIX1 is overexpressed in endometrial carcinoma and promotes the malignant behavior of cancer cells through ERK and AKT signaling. Oncol Lett 2016; 12:3435-3440. [PMID: 27900017 DOI: 10.3892/ol.2016.5098] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 07/07/2016] [Indexed: 01/05/2023] Open
Abstract
The sineoculis homeobox homolog 1 (SIX1) protein has been found to be important for cancer progression. However, its biological role in human endometrial carcinomas remains unexplored. The potential mechanism of SIX1-induced cancer progression remains unclear. In the present study, SIX1 protein expression was examined in 84 cases of endometrial carcinoma tissues using immunohistochemisty, and SIX1 was found to be overexpressed in 51.1% (43/84) of cervical cancer cells. Small interfering RNA (siRNA) knockdown of SIX1 was also performed in Ishikawa cells with high endogenous SIX1 expression, and SIX1 was overexpressed in the HEC1B cell line with low endogenous expression. SIX1 overexpression promoted cell growth rate and colony formation ability, whereas SIX1 depletion inhibited cell growth and colony formation. Further analysis showed that SIX1 knockdown downregulated, and SIX1 overexpression upregulated, cyclin D1, cyclin E, phosphorylated (p-)extracellular signal-regulated kinase (ERK), and p-protein kinase B (AKT) expression. The ERK inhibitor, U0126, and AKT inhibitor treatments blocked the effect of SIX1 on proliferation. In conclusion, the present study found that SIX1 overexpression promotes cancer cell growth in endometrial carcinoma, possibly through ERK- and AKT-mediated pathways.
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Affiliation(s)
- Xiaochuan Xin
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Yue Li
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
| | - Xianghong Yang
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, Liaoning 110004, P.R. China
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13
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Six family of homeobox genes and related mechanisms in tumorigenesis protocols. TUMORI JOURNAL 2016; 2016:236-43. [PMID: 27056337 DOI: 10.5301/tj.5000495] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2016] [Indexed: 12/14/2022]
Abstract
In recent years, the homeobox gene superfamily has been introduced as a master regulator in downstream target genes related to cell development and proliferation. An indispensable role of this family involved in organogenesis development has been widely demonstrated since expression of Six family led to a distinct increase in development of various organs. These functions of Six family genes are primarily based on structure as well as regulatory role in response to external or internal stimuli. In addition to these roles, mutation or aberrant expression of Six family plays a fundamental role in initiation of carcinogenesis, a multistep process including transformation, proliferation, angiogenesis, migration, and metastasis. This suggests that the Six superfamily members can be considered as novel target molecules to inhibit tumor growth and progression. This review focuses on the structure, function, and mechanisms of the Six family in cancer processes and possible strategies to apply these family members for diagnostic, prognostic, and therapeutic purposes.
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14
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Liu Y, Han N, Zhou S, Zhou R, Yuan X, Xu H, Zhang C, Yin T, Wu K. The DACH/EYA/SIX gene network and its role in tumor initiation and progression. Int J Cancer 2015; 138:1067-75. [PMID: 26096807 DOI: 10.1002/ijc.29560] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 03/31/2015] [Indexed: 01/08/2023]
Abstract
The functional abnormality of developmental genes is a common phenomenon in cancer initiation and progression. The retinal determination gene network (RDGN) is a key signal in Drosophila eye specification, and this conservative pathway is also required for the development of multiple organs in mammalian species. Recent studies demonstrated that aberrant expressions of RDGN components in vertebrates, mainly Dach, Six, and Eya, represent a novel tumor signal. RDGN regulates proliferation, apoptosis, tumor growth and metastasis through interactions with multiple signaling pathways in a co-ordinated fashion; Dach acts as a tumor suppressor, whereas Six and Eya function as oncogenes. Clinical analyses demonstrated that the expression levels of RDGN correlate with tumor stage, metastasis and survival, suggesting that combinational detection of this pathway might be used as a promising biomarker for the stratification of therapy and for the prediction of the prognosis of cancer patients.
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Affiliation(s)
- Yu Liu
- Department of Geriatrics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Na Han
- Department of Oncology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Si Zhou
- Department of Geriatrics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Rong Zhou
- Department of Geriatrics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Xun Yuan
- Department of Oncology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Hanxiao Xu
- Department of Oncology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Cuntai Zhang
- Department of Geriatrics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Tiejun Yin
- Department of Geriatrics, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Kongming Wu
- Department of Oncology, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
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15
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Liu D, Zhang XX, Xi BX, Wan DY, Li L, Zhou J, Wang W, Ma D, Wang H, Gao QL. Sine oculis homeobox homolog 1 promotes DNA replication and cell proliferation in cervical cancer. Int J Oncol 2014; 45:1232-40. [PMID: 24970368 DOI: 10.3892/ijo.2014.2510] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 05/26/2014] [Indexed: 11/05/2022] Open
Abstract
Malignant proliferation is the fundamental trait of tumor cells. The initiation of DNA replication represents a key process for cell proliferation, and has a marked impact on tumorigenesis and progression. Here we report that Sine oculis homeobox homolog 1 (SIX1) functions as a master regulator in DNA replication of cervical cancer cells. The expression of SIX1 was induced by the E7 oncoprotein of human papillomaviruses in cervical intraepithelial neoplasia and cervical cancer. The increase of SIX1 expression resulted in the upregulation of multiple genes related to the initiation of DNA replication, including the genes coding for the proteins in minichromosome maintenance complex (MCM2, MCM3, MCM6), DNA polymerase α-primase complex (POLA1, PRIM1, PRIM2), clamp loader (RFC3, RFC4, RFC5), DNA polymerase δ complex (POLD3) and DNA polymerase ε complex (POLE2). In line with this, the increase of SIX1 expression enhanced DNA synthesis, accelerated G1 to S phase progression, and promoted the proliferation of cervical cancer cells and the growth of cervical cancer. Consistently, knockdown of SIX1 could hamper DNA synthesis, slow down G1 to S phase progression, and suppress tumor cell proliferation and tumor growth. Importantly, SIX1 could more efficiently promote anchorage-independent cell growth. These results suggest that the increase of SIX1 expression could promote tumorigenesis, progression and invasive growth of cervical cancer by promoting DNA replication, and that targeting SIX1 may have significant therapeutic value in cervical cancer treatment.
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Affiliation(s)
- Dan Liu
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Xiao-Xue Zhang
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Bi-Xin Xi
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Dong-Yi Wan
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Li Li
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Jin Zhou
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Wei Wang
- Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University Guangzhou, Guangzhou, P.R. China
| | - Ding Ma
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Hui Wang
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
| | - Qing-Lei Gao
- Cancer Biology Research Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P.R. China
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16
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Boulay K, Ghram M, Viranaicken W, Trépanier V, Mollet S, Fréchina C, DesGroseillers L. Cell cycle-dependent regulation of the RNA-binding protein Staufen1. Nucleic Acids Res 2014; 42:7867-83. [PMID: 24906885 PMCID: PMC4081104 DOI: 10.1093/nar/gku506] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Staufen1 (Stau1) is a ribonucleic acid (RNA)-binding protein involved in the post-transcriptional regulation of gene expression. Recent studies indicate that Stau1-bound messenger RNAs (mRNAs) mainly code for proteins involved in transcription and cell cycle control. Consistently, we report here that Stau1 abundance fluctuates through the cell cycle in HCT116 and U2OS cells: it is high from the S phase to the onset of mitosis and rapidly decreases as cells transit through mitosis. Stau1 down-regulation is mediated by the ubiquitin-proteasome system and the E3 ubiquitin ligase anaphase promoting complex/cyclosome (APC/C). Stau1 interacts with the APC/C co-activators Cdh1 and Cdc20 via its first 88 N-terminal amino acids. The importance of controlling Stau155 levels is underscored by the observation that its overexpression affects mitosis entry and impairs proliferation of transformed cells. Microarray analyses identified 275 Stau155-bound mRNAs in prometaphase cells, an early mitotic step that just precedes Stau1 degradation. Interestingly, several of these mRNAs are more abundant in Stau155-containing complexes in cells arrested in prometaphase than in asynchronous cells. Our results point out for the first time to the possibility that Stau1 participates in a mechanism of post-transcriptional regulation of gene expression that is linked to cell cycle progression in cancer cells.
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Affiliation(s)
- Karine Boulay
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Mehdi Ghram
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Wildriss Viranaicken
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Véronique Trépanier
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Stéphanie Mollet
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Céline Fréchina
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
| | - Luc DesGroseillers
- Département de Biochimie, Faculté de médecine, Université de Montréal, 2900 Edouard Montpetit, Montréal, QC, H3T 1J4, Canada
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17
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Zhang J, Wan L, Dai X, Sun Y, Wei W. Functional characterization of Anaphase Promoting Complex/Cyclosome (APC/C) E3 ubiquitin ligases in tumorigenesis. Biochim Biophys Acta Rev Cancer 2014; 1845:277-93. [PMID: 24569229 DOI: 10.1016/j.bbcan.2014.02.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 02/09/2014] [Accepted: 02/12/2014] [Indexed: 12/25/2022]
Abstract
The Anaphase Promoting Complex/Cyclosome (APC/C) is a multi-subunit E3 ubiquitin ligase that primarily governs cell cycle progression. APC/C is composed of at least 14 core subunits and recruits its substrates for ubiquitination via one of the two adaptor proteins, Cdc20 or Cdh1, in M or M/early G1 phase, respectively. Furthermore, recent studies have shed light on crucial functions for APC/C in maintaining genomic integrity, neuronal differentiation, cellular metabolism and tumorigenesis. To gain better insight into the in vivo physiological functions of APC/C in regulating various cellular processes, particularly development and tumorigenesis, a number of mouse models of APC/C core subunits, coactivators or inhibitors have been established and characterized. However, due to their essential role in cell cycle regulation, most of the germline knockout mice targeting the APC/C pathway are embryonic lethal, indicating the need for generating conditional knockout mouse models to assess the role in tumorigenesis for each APC/C signaling component in specific tissues. In this review, we will first provide a brief introduction of the ubiquitin-proteasome system (UPS) and the biochemical activities and cellular functions of the APC/C E3 ligase. We will then focus primarily on characterizing genetic mouse models used to understand the physiological roles of each APC/C signaling component in embryogenesis, cell proliferation, development and carcinogenesis. Finally, we discuss future research directions to further elucidate the physiological contributions of APC/C components during tumorigenesis and validate their potentials as a novel class of anti-cancer targets.
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Affiliation(s)
- Jinfang Zhang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Lixin Wan
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Xiangpeng Dai
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Yi Sun
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
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18
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Wu W, Ren Z, Li P, Yu D, Chen J, Huang R, Liu H. Six1: A critical transcription factor in tumorigenesis. Int J Cancer 2014; 136:1245-53. [DOI: 10.1002/ijc.28755] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/15/2014] [Accepted: 01/20/2014] [Indexed: 12/16/2022]
Affiliation(s)
- Wangjun Wu
- Department of Animal Genetics; Breeding and Reproduction; College of Animal Science and Technology; Nanjing Agricultural University; Nanjing China
- Huaian Academy of Nanjing Agricultural University; Huaian Jiangsu China
| | - Zhuqing Ren
- Key Laboratory of Swine Genetics and Breeding; Ministry of Agriculture; Key Lab of Agriculture Animal Genetics; Breeding and Reproduction; Ministry of Education; College of Animal Science; Huazhong Agricultural University; Wuhan Hubei China
| | - Pinghua Li
- Department of Animal Genetics; Breeding and Reproduction; College of Animal Science and Technology; Nanjing Agricultural University; Nanjing China
| | - Debing Yu
- Department of Animal Genetics; Breeding and Reproduction; College of Animal Science and Technology; Nanjing Agricultural University; Nanjing China
| | - Jie Chen
- Department of Animal Genetics; Breeding and Reproduction; College of Animal Science and Technology; Nanjing Agricultural University; Nanjing China
| | - Ruihua Huang
- Department of Animal Genetics; Breeding and Reproduction; College of Animal Science and Technology; Nanjing Agricultural University; Nanjing China
| | - Honglin Liu
- Department of Animal Genetics; Breeding and Reproduction; College of Animal Science and Technology; Nanjing Agricultural University; Nanjing China
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19
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Musharraf A, Kruspe D, Tomasch J, Besenbeck B, Englert C, Landgraf K. BOR-syndrome-associated Eya1 mutations lead to enhanced proteasomal degradation of Eya1 protein. PLoS One 2014; 9:e87407. [PMID: 24489909 PMCID: PMC3906160 DOI: 10.1371/journal.pone.0087407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 12/27/2013] [Indexed: 11/18/2022] Open
Abstract
Mutations in the human EYA1 gene have been associated with several human diseases including branchio-oto (BO) and branchio-oto-renal (BOR) syndrome, as well as congenital cataracts and ocular anterior segment anomalies. BOR patients suffer from severe malformations of the ears, branchial arches and kidneys. The phenotype of Eya1-heterozygous mice resembles the symptoms of human patients suffering from BOR syndrome. The Eya1 gene encodes a multifunctional protein that acts as a protein tyrosine phosphatase and a transcriptional coactivator. It has been shown that Eya1 interacts with Six transcription factors, which are also required for nuclear translocation of the Eya1 protein. We investigated the effects of seven disease-causing Eya1 missense mutations on Eya1 protein function, in particular cellular localization, ability to interact with Six proteins, and protein stability. We show here that the BOR-associated Eya1 missense mutations S454P, L472R, and L550P lead to enhanced proteasomal degradation of the Eya1 protein in mammalian cells. Moreover, Six proteins lead to a significant stabilization of Eya1, which is caused by Six-mediated protection from proteasomal degradation. In case of the mutant L550P, loss of interaction with Six proteins leads to rapid protein degradation. Our observations suggest that protein destabilization constitutes a novel disease causing mechanism for Eya1.
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Affiliation(s)
- Amna Musharraf
- Leibniz Institute for Age Research - Fritz Lipmann Institute e. V. (FLI), Jena, Germany
| | - Dagmar Kruspe
- Leibniz Institute for Age Research - Fritz Lipmann Institute e. V. (FLI), Jena, Germany
| | - Jürgen Tomasch
- Leibniz Institute for Age Research - Fritz Lipmann Institute e. V. (FLI), Jena, Germany
| | - Birgit Besenbeck
- Leibniz Institute for Age Research - Fritz Lipmann Institute e. V. (FLI), Jena, Germany
| | - Christoph Englert
- Leibniz Institute for Age Research - Fritz Lipmann Institute e. V. (FLI), Jena, Germany
| | - Kathrin Landgraf
- Leibniz Institute for Age Research - Fritz Lipmann Institute e. V. (FLI), Jena, Germany
- * E-mail:
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20
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Kohrt D, Crary J, Zimmer M, Patrick AN, Ford HL, Hinds PW, Grossel MJ. CDK6 binds and promotes the degradation of the EYA2 protein. Cell Cycle 2013; 13:62-71. [PMID: 24196439 PMCID: PMC3925736 DOI: 10.4161/cc.26755] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cyclin-dependent kinase 6 (Cdk6) is a D-Cyclin-activated kinase that is directly involved in driving the cell cycle through inactivation of pRB in G1 phase. Increasingly, evidence suggests that CDK6, while directly driving the cell cycle, may only be essential for proliferation of specialized cell types, agreeing with the notion that CDK6 also plays an important role in differentiation. Here, evidence is presented that CDK6 binds to and promotes degradation of the EYA2 protein. The EYA proteins are a family of proteins that activate genes essential for the development of multiple organs, regulate cell proliferation, and are misregulated in several types of cancer. This interaction suggests that CDK6 regulates EYA2 activity, a mechanism that could be important in development and in cancer.
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Affiliation(s)
- Dawn Kohrt
- Department of Biology; Connecticut College; New London, CT USA
| | - Jennifer Crary
- Department of Biology; Connecticut College; New London, CT USA; Department of Developmental, Molecular, and Chemical Biology; Tufts University School of Medicine, and Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA
| | - Marc Zimmer
- Department of Chemistry; Connecticut College; New London, CT USA
| | - Aaron N Patrick
- Department of Pharmacology; University of Colorado School of Medicine; Aurora, CO USA
| | - Heide L Ford
- Department of Pharmacology; University of Colorado School of Medicine; Aurora, CO USA
| | - Philip W Hinds
- Department of Developmental, Molecular, and Chemical Biology; Tufts University School of Medicine, and Molecular Oncology Research Institute; Tufts Medical Center; Boston, MA USA
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The phosphatase-transcription activator EYA1 is targeted by anaphase-promoting complex/Cdh1 for degradation at M-to-G1 transition. Mol Cell Biol 2012; 33:927-36. [PMID: 23263983 DOI: 10.1128/mcb.01516-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The phosphatase and transactivator EYA family proteins are overexpressed in many cancer cell lines and are abundantly distributed in undifferentiated cells during development. Loss-of-function studies have shown that EYA1 is required for cell proliferation and survival during mammalian organogenesis. However, how EYA1 is regulated during development is unknown. Here, we report that EYA1 is regulated throughout the cell cycle via ubiquitin-mediated proteolysis. The level of EYA1 protein fluctuates in the cell cycle, peaking during mitosis and dropping drastically as cells exit into G(1). We found that EYA1 is efficiently degraded during mitotic exit in a Cdh1-dependent manner and that these two proteins physically interact. Overexpression of Cdh1 reduces the protein levels of ectopically expressed or endogenous EYA1, whereas depletion of Cdh1 by RNA interference stabilizes the EYA1 protein. Together, our results indicate that anaphase-promoting complex/cyclosome (APC/C)-Cdh1 specifically targets EYA1 for degradation during M-to-G(1) transition, failure of which may compromise cell proliferation and survival.
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Pandey RN, Rani R, Yeo EJ, Spencer M, Hu S, Lang RA, Hegde RS. The Eyes Absent phosphatase-transactivator proteins promote proliferation, transformation, migration, and invasion of tumor cells. Oncogene 2010; 29:3715-22. [PMID: 20418914 DOI: 10.1038/onc.2010.122] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The Eyes Absent (EYA) proteins combine transactivation, tyrosine phosphatase, and threonine phosphatase activities in their function as part of a conserved regulatory cascade involved in embryonic organ development. EYA tyrosine phosphatase activity contributes to fly eye development, and vertebrate EYA is involved in promoting DNA damage repair subsequent to genotoxic stress. EYAs are known to be expressed at elevated levels in ovarian and breast cancers. Here, we show that the tyrosine phosphatase activity of the EYAs promotes tumor cell migration, invasion, and transformation. These cellular effects are accompanied by alterations of the actin cytoskeleton and increased levels of active Rac and Cdc42. The invasiveness conferred by EYA is reflected in vivo by inhibition of metastasis seen when EYA3 expression is silenced in the invasive breast cancer cell line MDA-MB-231. Together, our data directly associate the tyrosine phosphatase activity of the EYAs with the oncogenesis-associated cellular properties of motility and invasiveness.
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Affiliation(s)
- R N Pandey
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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23
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Schlosser G. Making senses development of vertebrate cranial placodes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:129-234. [PMID: 20801420 DOI: 10.1016/s1937-6448(10)83004-7] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cranial placodes (which include the adenohypophyseal, olfactory, lens, otic, lateral line, profundal/trigeminal, and epibranchial placodes) give rise to many sense organs and ganglia of the vertebrate head. Recent evidence suggests that all cranial placodes may be developmentally related structures, which originate from a common panplacodal primordium at neural plate stages and use similar regulatory mechanisms to control developmental processes shared between different placodes such as neurogenesis and morphogenetic movements. After providing a brief overview of placodal diversity, the present review summarizes current evidence for the existence of a panplacodal primordium and discusses the central role of transcription factors Six1 and Eya1 in the regulation of processes shared between different placodes. Upstream signaling events and transcription factors involved in early embryonic induction and specification of the panplacodal primordium are discussed next. I then review how individual placodes arise from the panplacodal primordium and present a model of multistep placode induction. Finally, I briefly summarize recent advances concerning how placodal neurons and sensory cells are specified, and how morphogenesis of placodes (including delamination and migration of placode-derived cells and invagination) is controlled.
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Affiliation(s)
- Gerhard Schlosser
- Zoology, School of Natural Sciences & Martin Ryan Institute, National University of Ireland, Galway, Ireland
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24
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Weasner BP, Kumar JP. The non-conserved C-terminal segments of Sine Oculis Homeobox (SIX) proteins confer functional specificity. Genesis 2009; 47:514-23. [PMID: 19422020 DOI: 10.1002/dvg.20517] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Sine Oculis Homeobox (SIX) proteins play critical roles in organogenesis and are defined by the presence of two evolutionarily conserved functional motifs: a homeobox DNA binding domain and the SIX protein-protein interaction domain. Members of this transcription factor family can be divided into three subgroups: Six1/2, Six4/5, and Six3/6. This partitioning is based mainly on protein sequence similarity and genomic architecture, and not on specificities of DNA binding or binding partners. In fact, it is well demonstrated that members of the different subgroups can bind to and activate common transcriptional targets as well as form biochemical complexes with communal binding partners. Here we report that the C-terminal segment, which is not conserved across different SIX subfamilies, may serve to functionally distinguish individual SIX proteins. In particular, we have dissected the C-terminal region of Optix, the Drosophila ortholog of mammalian Six3/6, and identified three regions that distinguish Optix from Sine Oculis, the fly homolog of Six1/2. Two of these regions have been preserved in all Six3/6 family members while the third section is present only within Optix proteins in the Drosophilids. The activities of these regions are required, in unison, for Optix function. We suggest that biochemical/functional differences between members of large protein families as well as proteins encoded by duplicate genes can, in part, be attributed to the activities of nonconserved segments. Finally, we demonstrate that a subset of vertebrate SIX proteins has retained the ability to function during normal fly eye development but have lost the ability to induce the formation of ectopic eyes.
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Affiliation(s)
- Brandon P Weasner
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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25
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Patrick AN, Schiemann BJ, Yang K, Zhao R, Ford HL. Biochemical and functional characterization of six SIX1 Branchio-oto-renal syndrome mutations. J Biol Chem 2009; 284:20781-90. [PMID: 19497856 DOI: 10.1074/jbc.m109.016832] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Branchio-oto-renal syndrome (BOR) is an autosomal dominant developmental disorder characterized by hearing loss, branchial arch defects, and renal anomalies. Recently, eight mutations in the SIX1 homeobox gene were discovered in BOR patients. To characterize the effect of SIX1 BOR mutations on the EYA-SIX1-DNA complex, we expressed and purified six of the eight mutants in Escherichia coli. We demonstrate that only the most N-terminal mutation in SIX1 (V17E) completely abolishes SIX1-EYA complex formation, whereas all of the other mutants are able to form a stable complex with EYA. We further show that only the V17E mutant fails to localize EYA to the nucleus and cannot be stabilized by EYA in the cell. The remaining five SIX1 mutants are instead all deficient in DNA binding. In contrast, V17E alone has a DNA binding affinity similar to that of wild type SIX1 in complex with the EYA co-factor. Finally, we show that all SIX1 BOR mutants are defective in transcriptional activation using luciferase reporter assays. Taken together, our experiments demonstrate that the SIX1 BOR mutations contribute to the pathology of the disease through at least two different mechanisms that involve: 1) abolishing the formation of the SIX1-EYA complex or 2) diminishing the ability of SIX1 to bind DNA. Furthermore, our data demonstrate for the first time that EYA: 1) requires the N-terminal region of the SIX1 Six domain for its interaction, 2) increases the level of the SIX1 protein within the cell, and 3) increases the DNA binding affinity of SIX1.
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Affiliation(s)
- Aaron N Patrick
- Program in Molecular Biology, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA
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26
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Kumar JP. The sine oculis homeobox (SIX) family of transcription factors as regulators of development and disease. Cell Mol Life Sci 2009; 66:565-83. [PMID: 18989625 PMCID: PMC2716997 DOI: 10.1007/s00018-008-8335-4] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The sine oculis homeobox (SIX) protein family is a group of evolutionarily conserved transcription factors that are found in diverse organisms that range from flatworms to humans. These factors are expressed within, and play pivotal developmental roles in, cell populations that give rise to the head, retina, ear, nose, brain, kidney, muscle and gonads. Mutations within the fly and mammalian versions of these genes have adverse consequences on the development of these organs/tissues. Several SIX proteins have been shown to directly influence the cell cycle and are present at elevated levels during tumorigenesis and within several cancers. This review aims to highlight aspects of (1) the evolutionary history of the SIX family; (2) the structural differences and similarities amongst the different SIX proteins; (3) the role that these genes play in retinal development; and (4) the influence that these proteins have on cell proliferation and growth.
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Affiliation(s)
- J P Kumar
- Department of Biology, Indiana University, Bloomington, 47405, USA.
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27
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Christensen KL, Patrick AN, McCoy EL, Ford HL. The six family of homeobox genes in development and cancer. Adv Cancer Res 2009; 101:93-126. [PMID: 19055944 DOI: 10.1016/s0065-230x(08)00405-3] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The homeobox gene superfamily encodes transcription factors that act as master regulators of development through their ability to activate or repress a diverse range of downstream target genes. Numerous families exist within the homeobox gene superfamily, and are classified on the basis of conservation of their homeodomains as well as additional motifs that contribute to DNA binding and to interactions with other proteins. Members of one such family, the Six family, form a transcriptional complex with Eya and Dach proteins, and together these proteins make up part of the retinal determination network first identified in Drosophila. This network is highly conserved in both invertebrate and vertebrate species, where it influences the development of numerous organs in addition to the eye, primarily through regulation of cell proliferation, survival, migration, and invasion. Mutations in Six, Eya, and Dach genes have been identified in a variety of human genetic disorders, demonstrating their critical role in human development. In addition, aberrant expression of Six, Eya, and Dach occurs in numerous human tumors, and Six1, in particular, plays a causal role both in tumor initiation and in metastasis. Emerging evidence for the importance of Six family members and their cofactors in numerous human tumors suggests that targeting of this complex may be a novel and powerful means to inhibit both tumor growth and progression.
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Affiliation(s)
- Kimberly L Christensen
- Program in Molecular Biology, University of Colorado School of Medicine, Denver, Colorado, USA
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28
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Coletta RD, Christensen KL, Micalizzi DS, Jedlicka P, Varella-Garcia M, Ford HL. Six1 overexpression in mammary cells induces genomic instability and is sufficient for malignant transformation. Cancer Res 2008; 68:2204-13. [PMID: 18381426 DOI: 10.1158/0008-5472.can-07-3141] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Homeoproteins are transcription factors that act as master regulators of development and are frequently dysregulated in cancers. During embryogenesis, the Six1 homeoprotein is essential for the expansion of precursor cell populations that give rise to muscle and kidney, among other organs. Six1 overexpression is observed in numerous cancers, resulting in increased proliferation, survival, and metastasis. Here, we investigate whether Six1 can play a causal role in mammary tumor initiation. We show that Six1 overexpression in MCF12A mammary epithelial cells promotes multiple properties associated with malignant transformation, including increased proliferation, genomic instability, and anchorage-independent growth. We further show that this transformation is dependent on up-regulation of its transcriptional target, cyclin A1, which is normally expressed in the embryonic mammary gland but dramatically reduced in the adult gland. Six1-transformed MCF12A cells are tumorigenic in nude mice, forming aggressive tumors that are locally invasive and exhibit peritumoral lymphovascular invasion. In human breast carcinomas, expression of Six1 and cyclin A1 mRNA correlate strongly with each other (P < 0.0001), and expression of Six1 and cyclin A1 each correlate with Ki67, a marker of proliferation (P < 0.0001 and P = 0.014, respectively). Together, our data indicate that Six1 overexpression is sufficient for malignant transformation of immortalized, nontumorigenic mammary epithelial cells, and suggest that the mechanism of this transformation involves inappropriate reexpression of cyclin A1 in the adult mammary gland.
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Affiliation(s)
- Ricardo D Coletta
- Department of Obstretrics and Gynecology, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
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