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Yang X, Zhu Q. SPOP in Cancer: Phenomena, Mechanisms and Its Role in Therapeutic Implications. Genes (Basel) 2022; 13:2051. [PMID: 36360288 PMCID: PMC9690554 DOI: 10.3390/genes13112051] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Revised: 10/14/2022] [Accepted: 11/04/2022] [Indexed: 11/15/2023] Open
Abstract
Speckle-type POZ (pox virus and zinc finger protein) protein (SPOP) is a cullin 3-based E3 ubiquitin ligase adaptor protein that plays a crucial role in ubiquitin-mediated protein degradation. Recently, SPOP has attracted major research attention as it is frequently mutated in a range of cancers, highlighting pleiotropic tumorigenic effects and associations with treatment resistance. Structurally, SPOP contains a functionally critical N-terminal meprin and TRAF homology (MATH) domain for many SPOP substrates. SPOP has two other domains, including the internal Bric-a-brac-Tramtrack/Broad (BTB) domain, which is linked with SPOP dimerization and binding to cullin3, and a C-terminal nuclear localization sequence (NLS). The dysregulation of SPOP-mediated proteolysis is associated with the development and progression of different cancers since abnormalities in SPOP function dysregulate cellular signaling pathways by targeting oncoproteins or tumor suppressors in a tumor-specific manner. SPOP is also involved in genome stability through its role in the DNA damage response and DNA replication. More recently, studies have shown that the expression of SPOP can be modulated in various ways. In this review, we summarize the current understanding of SPOP's functions in cancer and discuss how to design a rational therapeutic target.
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Affiliation(s)
| | - Qing Zhu
- Department of Abdominal Oncology, West China Hospital of Sichuan University, Chengdu 610041, China
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2
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Wu L, Yu K, Cue Y, Zhu X, Yang Z, Ma J. [Speckle-type POZ protein up-regulates c-Jun protein expression and promotes proliferation and invasion of renal carcinoma cells]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2021; 41:447-452. [PMID: 33849838 DOI: 10.12122/j.issn.1673-4254.2021.03.19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the effect of speckle-type POZ protein (SPOP) on proliferation, apoptosis, migration and invasion of renal cell carcinoma (RCC) and explore the potential mechanisms. OBJECTIVE Renal carcinoma cell lines (786-O, A704, and Caki-2) cultured in vitro were transfected with a SPOP-overexpressing plasmid, and the changes in proliferation of the cells were detected using colony formation and MTT assay; TUNEL assay was used to assess apoptosis of the cells. The changes in migration and invasion abilities of the cells were examined using wound healing assay and Transwell assay. The mRNA and protein levels of SPOP and c-Jun in the transfected cells were measured using real-time PCR and Western blotting. OBJECTIVE SPOP over-expression obviously promoted the proliferation, migration and invasion of 786-O, A704 and Caki-2 cells (P < 0.05). Compared with the control cells, 786-o and Caki-2 cells over-expressing SPOP exhibited significantly lowered apoptosis rates (P < 0.05). The results of real-time PCR demonstrated that the transfected cells did not show obvious changes in the mRNA level of c-Jun, but the protein expressions of SPOP and c-jun increased significantly as shown by Western blotting (P < 0.05). OBJECTIVE SPOP can promote proliferation, migration, and invasion and suppress apoptosis of renal carcinoma cells possibly by promoting the expression of c-Jun.
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Affiliation(s)
- L Wu
- Key Laboratory of Cancer Research and Clinical Laboratory Diagnosis, Bengbu 233030, China
| | - K Yu
- Key Laboratory of Cancer Research and Clinical Laboratory Diagnosis, Bengbu 233030, China
| | - Y Cue
- Department of Clinical Laboratory, Fuyang Women and Children's Hospital, Fuyang 236000, China
| | - X Zhu
- Department of Laboratory Medicine, Bengbu 233030, China
| | - Z Yang
- Department of Laboratory Medicine, Bengbu 233030, China
| | - J Ma
- Department of Biochemistry and Molecular Biology, School of Laboratory Medicine, Bengbu Medical College, Bengbu 233030, China
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Abstract
Multiple studies have confirmed that speckle-type pox virus and zinc finger (POZ) protein (SPOP) functions as a substrate adaptor of cullin 3-based E3 ligase and has a crucial role in various cellular processes via specific targeting of proteins for ubiquitination and subsequent proteasomal degradation. Dysregulation of SPOP-mediated proteolysis might be involved in the development and progression of human prostate and kidney cancers. In prostate cancer, SPOP seems to function as a tumour suppressor by targeting several proteins, including androgen receptor (AR), steroid receptor coactivator 3 (SRC3) and BRD4, for degradation, whereas it might function as an oncoprotein in kidney cancer, for example, by targeting phosphatase and tensin homologue (PTEN) for proteasomal degradation. In addition, nuclear SPOP targets AR for degradation and has a role as a tumour suppressor in prostate cancer; however, in kidney cancer, SPOP largely accumulates in the cytoplasm and fails to promote degradation of AR located in the nucleus, resulting in activation of AR-driven pathways and cancer progression. Owing to the context-dependent function of SPOP in human malignancies, further assessment of the molecular mechanisms involving SPOP in prostate and kidney cancers is needed to improve our understanding of its role in the development of these cancer types. Treatments that target SPOP might become therapeutic strategies in these malignancies in the future.
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Clark A, Burleson M. SPOP and cancer: a systematic review. Am J Cancer Res 2020; 10:704-726. [PMID: 32266086 PMCID: PMC7136909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 02/27/2020] [Indexed: 06/11/2023] Open
Abstract
The initiation and progression of cancer is dependent on the acquisition of mutations in oncogenes or tumor suppressor genes that ultimately leads to the dysregulation of key regulatory pathways. Though these mutations often occur in direct regulators of such pathways, some may confer tumorigenic potential by indirectly targeting several pathways congruently thereby exerting pleiotropic effects. In recent years, the tumor suppressor gene Speckle Type POZ Protein (SPOP) has gained a lot of attention as it has been found to be altered in a variety of different cancers. SPOP appears to exert pleiotropic tumorigenic effects as multiple different regulatory pathways become dysregulated upon SPOP alterations. SPOP has been identified as an E3 ubiquitin ligase substrate binding subunit of the proteasome complex. Since protein degradation is critical in regulating proper cellular function it is not surprising that the proteasome pathway is often found to be disrupted in cancer. Many studies have now indicated that mutations or changes in the expression of SPOP are one of several underlying reasons of proteasome pathway disruption in different cancers. Ultimately, either SPOP downregulation or mutation promotes stabilization of direct SPOP targets which subsequently promotes cancer through the dysregulation of key regulatory pathways. In this review, we will discuss the current literature on cancer-specific SPOP alterations as well the SPOP targets that are stabilized, and the pathways that are dysregulated, as a result.
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Affiliation(s)
- Alison Clark
- Department of Biology, University of Texas at San AntonioSan Antonio, TX, USA
| | - Marieke Burleson
- Department of Biology, University of The Incarnate WordSan Antonio, TX, USA
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Song Y, Xu Y, Pan C, Yan L, Wang ZW, Zhu X. The emerging role of SPOP protein in tumorigenesis and cancer therapy. Mol Cancer 2020; 19:2. [PMID: 31901237 DOI: 10.1186/s12943019-1124-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/23/2019] [Indexed: 05/26/2023] Open
Abstract
The nuclear speckle-type pox virus and zinc finger (POZ) protein (SPOP), a representative substrate-recognition subunit of the cullin-RING E3 ligase, has been characterized to play a dual role in tumorigenesis and cancer progression. Numerous studies have determined that SPOP suppresses tumorigenesis in a variety of human malignancies such as prostate, lung, colon, gastric, and liver cancers. However, several studies revealed that SPOP exhibited oncogenic function in kidney cancer, suggesting that SPOP could exert its biological function in a cancer type-specific manner. The role of SPOP in thyroid, cervical, ovarian, bone and neurologic cancers has yet to be determined. In this review article, we describe the structure and regulation of SPOP in human cancer. Moreover, we highlight the critical role of SPOP in tumorigenesis based on three major categories: physiological evidence (animal models), pathological evidence (human cancer specimens) and biochemical evidence (downstream ubiquitin substrates). Furthermore, we note that SPOP could be a promising therapeutic target for cancer treatment.
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Affiliation(s)
- Yizuo Song
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Yichi Xu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Chunyu Pan
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Linzhi Yan
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Zhi-Wei Wang
- Center of Scientific Research, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China.
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
| | - Xueqiong Zhu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China.
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Song Y, Xu Y, Pan C, Yan L, Wang ZW, Zhu X. The emerging role of SPOP protein in tumorigenesis and cancer therapy. Mol Cancer 2020; 19:2. [PMID: 31901237 PMCID: PMC6942384 DOI: 10.1186/s12943-019-1124-x] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/23/2019] [Indexed: 12/24/2022] Open
Abstract
The nuclear speckle-type pox virus and zinc finger (POZ) protein (SPOP), a representative substrate-recognition subunit of the cullin-RING E3 ligase, has been characterized to play a dual role in tumorigenesis and cancer progression. Numerous studies have determined that SPOP suppresses tumorigenesis in a variety of human malignancies such as prostate, lung, colon, gastric, and liver cancers. However, several studies revealed that SPOP exhibited oncogenic function in kidney cancer, suggesting that SPOP could exert its biological function in a cancer type-specific manner. The role of SPOP in thyroid, cervical, ovarian, bone and neurologic cancers has yet to be determined. In this review article, we describe the structure and regulation of SPOP in human cancer. Moreover, we highlight the critical role of SPOP in tumorigenesis based on three major categories: physiological evidence (animal models), pathological evidence (human cancer specimens) and biochemical evidence (downstream ubiquitin substrates). Furthermore, we note that SPOP could be a promising therapeutic target for cancer treatment.
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Affiliation(s)
- Yizuo Song
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Yichi Xu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Chunyu Pan
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Linzhi Yan
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China
| | - Zhi-Wei Wang
- Center of Scientific Research, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China. .,Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
| | - Xueqiong Zhu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, No. 109 Xueyuan Xi Road, Wenzhou, 325027, Zhejiang, China.
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7
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Cuneo MJ, Mittag T. The ubiquitin ligase adaptor SPOP in cancer. FEBS J 2019; 286:3946-3958. [PMID: 31495053 DOI: 10.1111/febs.15056] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/20/2019] [Accepted: 09/03/2019] [Indexed: 12/20/2022]
Abstract
The dysregulation of ubiquitin-mediated proteasomal degradation has emerged as an important mechanism of pathogenesis in several cancers. The speckle-type POZ protein (SPOP) functions as a substrate adaptor for the cullin3-RING ubiquitin ligase and controls the cellular persistence of a diverse array of protein substrates in hormone signalling, epigenetic control and cell cycle regulation, to name a few. Mutations in SPOP and the resulting dysregulation of this proteostatic pathway play causative roles in the pathogenesis of prostate and endometrial cancers, whereas overexpression and mislocalization are associated with kidney cancer. Understanding the molecular mechanism of the normal function of SPOP as well as the cause of SPOP-mediated oncogenesis is thus critical for eventual therapeutic targeting of SPOP and other related pathways. Here, we will review SPOP structure, function and the molecular mechanism of how this function is achieved. We will then review how mutations and protein mislocalization contribute to cancer pathogenesis and will provide a perspective on how SPOP may be targeted therapeutically.
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Affiliation(s)
- Matthew J Cuneo
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Tanja Mittag
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
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8
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Hai L, Szwarc MM, He B, Lonard DM, Kommagani R, DeMayo FJ, Lydon JP. Uterine function in the mouse requires speckle-type poz protein. Biol Reprod 2019; 98:856-869. [PMID: 29546395 DOI: 10.1093/biolre/ioy060] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 03/06/2018] [Indexed: 12/19/2022] Open
Abstract
Speckle-type poz protein (SPOP) is an E3-ubiquitin ligase adaptor for turnover of a diverse number of proteins involved in key cellular processes such as chromatin remodeling, transcriptional regulation, and cell signaling. Genomic analysis revealed that SPOP somatic mutations are found in a subset of endometrial cancers, suggesting that these mutations act as oncogenic drivers of this gynecologic malignancy. These studies also raise the question as to the role of wild-type SPOP in normal uterine function. To address this question, we generated a mouse model (Spopd/d) in which SPOP is ablated in uterine cells that express the PGR. Fertility studies demonstrated that SPOP is required for embryo implantation and for endometrial decidualization. Molecular analysis revealed that expression levels of the PGR at the protein and transcript level are significantly reduced in the Spopd/d uterus. While this result was unexpected, this finding explains in part the dysfunctional phenotype of the Spopd/d uterus. Moderate increased levels of the ESR1, GATA2, and SRC2 were detected in the Spopd/d uterus, suggesting that SPOP is required to maintain the proteome for normal uterine function. With age, the Spopd/d endometrium exhibits large glandular cysts with foci of epithelial proliferation, further supporting a role for SPOP in maintaining a healthy uterus. Collectively, studies on the Spopd/d mouse support an important role for SPOP in normal uterine function and suggest that this mouse model may prove useful to study the role of SPOP-loss-of-function mutations in the etiopathogenesis of endometrial cancer.
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Affiliation(s)
- Lan Hai
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Maria M Szwarc
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Bin He
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - David M Lonard
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Ramakrishna Kommagani
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Francesco J DeMayo
- Reproductive and Developmental Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - John P Lydon
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
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9
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Wei X, Fried J, Li Y, Hu L, Gao M, Zhang S, Xu B. Functional roles of Speckle-Type Poz (SPOP) Protein in Genomic stability. J Cancer 2018; 9:3257-3262. [PMID: 30271484 PMCID: PMC6160670 DOI: 10.7150/jca.25930] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/27/2018] [Indexed: 12/27/2022] Open
Abstract
Understanding the functional significance of the essential elements in maintaining genomic stability provides insights into the process of tumor initiation and progression, and predicts therapeutic responses. One such element that has recently attracted significant attention is the Speckle-Type Poz Protein (SPOP), an E3 ubiquitin ligase adaptor protein. SPOP is frequently mutated or has altered expression in various cancers, including prostate, renal and endometrial. SPOP is involved in the regulation of proteasome-mediated degradation of several oncoproteins. Moreover, recent data also indicate SPOP's direct involvement in the DNA damage response. SPOP mutants induce alternations in the DNA damage repair pathway by promoting the error-prone Non-homologous end joining (NHEJ) pathway. SPOP has been linked with significant functions in cellular signaling pathways and cancer suppression. This mini-review will discuss recent findings regarding SPOP's role in genomic stability in the pathological setting.
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Affiliation(s)
- Xi Wei
- Department of Diagnostic and Therapeutic Ultrasonography, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
| | - Joshua Fried
- Department of Oncology, Southern Research Institute and Cancer Cell Biology Program, University of Alabama at Birmingham Graduate School, Birmingham, AL, 35205.,Cancer Cell Biology Program, University of Alabama at Birmingham Comprehensive Cancer Center Birmingham, AL 35205, USA
| | - Ying Li
- The Third Department of Breast Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
| | - Linfei Hu
- Department of Thyroid and Cervical Tumor, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
| | - Ming Gao
- Department of Thyroid and Cervical Tumor, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
| | - Sheng Zhang
- Department of Diagnostic and Therapeutic Ultrasonography, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center of Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
| | - Bo Xu
- Department of Oncology, Southern Research Institute and Cancer Cell Biology Program, University of Alabama at Birmingham Graduate School, Birmingham, AL, 35205.,Cancer Cell Biology Program, University of Alabama at Birmingham Comprehensive Cancer Center Birmingham, AL 35205, USA.,Key Laboratory of Breast Cancer Prevention and Therapy, Ministry of Education, National Clinical Research Center of Cancer, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
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10
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Functional analysis of Cullin 3 E3 ligases in tumorigenesis. Biochim Biophys Acta Rev Cancer 2017; 1869:11-28. [PMID: 29128526 DOI: 10.1016/j.bbcan.2017.11.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/06/2017] [Accepted: 11/06/2017] [Indexed: 12/14/2022]
Abstract
Cullin 3-RING ligases (CRL3) play pivotal roles in the regulation of various physiological and pathological processes, including neoplastic events. The substrate adaptors of CRL3 typically contain a BTB domain that mediates the interaction between Cullin 3 and target substrates to promote their ubiquitination and subsequent degradation. The biological implications of CRL3 adaptor proteins have been well described where they have been found to play a role as either an oncogene, tumor suppressor, or can mediate either of these effects in a context-dependent manner. Among the extensively studied CRL3-based E3 ligases, the role of the adaptor protein SPOP (speckle type BTB/POZ protein) in tumorigenesis appears to be tissue or cellular context dependent. Specifically, SPOP acts as a tumor suppressor via destabilizing downstream oncoproteins in many malignancies, especially in prostate cancer. However, SPOP has largely an oncogenic role in kidney cancer. Keap1, another well-characterized CRL3 adaptor protein, likely serves as a tumor suppressor within diverse malignancies, mainly due to its specific turnover of its downstream oncogenic substrate, NRF2 (nuclear factor erythroid 2-related factor 2). In accordance with the physiological role the various CRL3 adaptors exhibit, several pharmacological agents have been developed to disrupt its E3 ligase activity, therefore blocking its potential oncogenic activity to mitigate tumorigenesis.
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Wang XH, Chen ZG, Xu RL, Lv CQ, Liu J, Du B. TGF-β1 signaling pathway serves a role in HepG2 cell regulation by affecting the protein expression of PCNA, gankyrin, p115, XIAP and survivin. Oncol Lett 2017; 13:3239-3246. [PMID: 28529566 DOI: 10.3892/ol.2017.5814] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 11/11/2016] [Indexed: 02/06/2023] Open
Abstract
The transforming growth factor-β (TGF-β) signaling pathway serves a key role in the pathogenesis of liver cancer. To investigate the association between TGF-β1 and the following proteins: Proliferating cell nuclear antigen (PCNA), gankyrin, general vesicular transport factor p115 (p115), X-linked inhibitor of apoptosis protein (XIAP) and survivin, HepG2 liver cancer cells were transfected with small interfering RNA (siRNA) directed against TGF-β1, or were treated with exogenous TGF-β1. TGF-β1 protein expression levels were assessed at 72 and 96 h using western blotting, cell growth was evaluated using a Cell Counting kit-8 assay, and flow cytometry was used to examine cell cycle distribution and apoptosis. In addition, PCNA, gankyrin, p115, XIAP and survivin protein levels were evaluated using western blotting. TGF-β1 protein expression levels were decreased at 72 and 96 h following siRNA transfection, indicating that the siRNA against TGF-β1 was effective. In the TGF-β1-knockdown group, the HepG2 cells exhibited G1 or S-phase cell cycle arrest; therefore, the number of G2-phase cells was decreased, cell growth was inhibited and apoptotic peaks were observed. By contrast, no significant alteration in cell cycle distribution or apoptosis was observed in the cells treated with exogenous TGF-β1. In the exogenous TGF-β1 group, PCNA and XIAP protein expression levels were increased, whereas gankyrin, p115 and survivin protein expression was observed to be dependent on the duration of treatment. By contrast, PCNA, gankyrin, XIAP and survivin protein expression decreased following TGF-β1 knockdown; however, p115 protein expression increased. In conclusion, the TGF-β1 signaling pathway may affect cell growth, cell cycle distribution and apoptosis through the regulation of PCNA, gankyrin, p115, XIAP and survivin protein expression in liver cancer. The results of the present study may improve the current understanding of the role of the TGF-β signaling pathway during the pathogenesis of liver cancer.
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Affiliation(s)
- Xin-Hong Wang
- Department of Gastroenterology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Zhi-Guo Chen
- Center of Educational Technology and Information, Mudanjiang Medical University, Mudanjiang, Heilongjiang 157011, P.R. China
| | - Rui-Ling Xu
- Department of Gastroenterology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Cheng-Qian Lv
- Department of Gastroenterology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Jing Liu
- Department of Gastroenterology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
| | - Bing Du
- Department of Gastroenterology, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang 150086, P.R. China
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