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Cao K, Liu Z, Liu J, Hu Q, Shan W, Hu B, Shi H, Zhang B. Constitutive photomorphogenic protein 1 ubiquitinates interleukin-1 receptor accessory protein in human liver cancer. J Cancer Res Clin Oncol 2023; 149:16247-16260. [PMID: 37700160 DOI: 10.1007/s00432-023-05367-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Accepted: 08/29/2023] [Indexed: 09/14/2023]
Abstract
BACKGROUND Constitutive photomorphogenic protein 1 (COP1) plays a pivotal role in the development and progression of several human cancers and is reported to be upregulated in liver cancer. However, the role of COP1 in human liver cancer is unclear. METHODS We analyzed the COP1 expression in normal liver and liver cancer tissue samples using western blot and immunohistochemical analysis. We overexpressed and silenced COP1 in HepG2 and Huh7 cells and analyzed the effect on liver cancer cell proliferation. Additionally, COP1 was used as a bait to screen COP1-interacting proteins in a human cDNA library in a yeast two-hybrid screen and the results were confirmed with co-immunoprecipitation (co-IP) assays. Moreover, immunofluorescence staining was performed to assess co-localization. The protein levels of COP1 and mIL1RAcP were determined in clinical samples. RESULTS COP1 was upregulated in liver cancer samples compared to that in normal tissue samples. COP1 overexpression promoted proliferation of liver cancer cells, while COP1 knockdown exerted the opposite effect. Yeast two-hybrid screen identified interleukin-1 receptor accessory protein (IL1RAP) as a potential COP1-interacting protein. Co-IP assays further confirmed that COP1 interacts with both preIL1RAP and membrane-bound form of IL1RAP (mIL1RAP). Furthermore, COP1 upregulated mIL1RAP protein levels and promoted nuclear translocation and activation of the nuclear factor kappa B (NF-κB) (p50/p65) dimer. Additionally, we demonstrated that COP1 regulated mIL1RAP expression through K63-linked polyubiquitination, suggesting that COP1 plays a role in stabilizing mIL1RAP. Finally, the protein levels of COP1 and mIL1RAcP were found to be positively correlated in clinical samples. CONCLUSION COP1 regulates IL1RAP, which in turn results in activation of the NF-κB signaling. Our findings suggest that the COP1/IL1RAP/NF-κB axis promotes proliferation of liver cancer cells and is a potential target for the treatment of liver cancer.
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Affiliation(s)
- Kuan Cao
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Zhiyi Liu
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Jin Liu
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Hepatobiliary Pancreatic Surgery, The Second Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Qinghe Hu
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Wengang Shan
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Bin Hu
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Hengliang Shi
- Institute of Digestive Diseases, Xuzhou Medical University, No. 84 West Huaihai Road, Xuzhou, 221002, Jiangsu, China.
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
- Central Laboratory, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
| | - Bin Zhang
- Research Center of Digestive Diseases, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
- Department of General Surgery, The Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China.
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Zhao B, Wu J, Cha X, Mao G, Shi H, Fei S, Miao B. Effect of COP1 in Promoting the Tumorigenesis of Gastric Cancer by Down-Regulation of CDH18 via PI3K/AKT Signal Pathway. Anal Cell Pathol (Amst) 2023; 2023:5617875. [PMID: 37025097 PMCID: PMC10072965 DOI: 10.1155/2023/5617875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/21/2023] [Accepted: 03/10/2023] [Indexed: 03/30/2023] Open
Abstract
In recent years, the involvement of E3 ubiquitin ligase constitutive photomorphogenesis 1 (COP1) in the tumorigenesis of gastric cancer (GC) has been elucidated. However, the exact underlying mechanism remains to be clarified. In the present study, the expression profiles of COP1 in GC were derived from the Gene Expression Omnibus (GEO) and the Cancer Genome Atlas (TCGA) databases, followed by verification via immunohistochemical staining (IHC), Western blotting (WB), and quantitative real-time polymerase chain reaction (qRT-PCR) reaction assays on clinical samples. In vitro, the gain- and loss-of-function experiments of COP1 protein were conducted to explore its role in GC cell lines HGC-27 and SGC-7901. Furthermore, we screened the interaction protein of COP1 by yeast two-hybrid experiment and verified their combination by co-immunoprecipitation (co-IP). We preliminary explored the possible underlying mechanisms of COP1 protein in GC cell lines via WB. COP1 was upregulated in GC tissues compared with the corresponding non-carcinoma tissues. In vitro, the upregulation of COP1 protein promoted the proliferation and migration of GC cells. The yeast two-hybrid experiment and co-IP indicated that Cadherin 18 (CDH18) could constitute a complex with COP1. Moreover, cells with COP1 over-expression showed low levels of CDH18 expression, with the intracellular PI3K/AKT pathway activated and the malignancy of GC cell lines enhanced. Our findings demonstrated that COP1 promoted the GC tumorigenesis by downregulated CDH18 with the involvement of PI3K/AKT signaling pathway in cell lines, suggesting the potential of COP1 as a prognostic biomarker and therapeutic target for GC.
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Peng HH, Yang HC, Rupa D, Yen CH, Chiu YW, Yang WJ, Luo FJ, Yuan TC. ACK1 upregulated the proliferation of head and neck squamous cell carcinoma cells by promoting p27 phosphorylation and degradation. J Cell Commun Signal 2022; 16:567-578. [PMID: 35247157 PMCID: PMC9733751 DOI: 10.1007/s12079-022-00670-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 02/02/2022] [Indexed: 12/24/2022] Open
Abstract
Head and neck squamous cell carcinoma (HNSCC) is a malignancy with a worldwide distribution. Although intensive studies have been made, the underlying oncogenic mechanism of HNSCC requires further investigation. In this study, we examined the oncogenic role of activated Cdc42-associated kinase 1 (ACK1), an oncogenic tyrosine kinase, in regulating the proliferation of HNSCC cells and its underlying molecular mechanism. Results from immunohistochemical studies revealed that ACK1 was highly expressed in HNSCC tumors, with 77% (77/100) of tumors showing a high ACK1 immunoreactivity compared to 40% (8/20) of normal mucosa. Knockdown of ACK1 expression in HNSCC cells resulted in elevated p27 expression, reduced cell proliferation, and G1-phase cell cycle arrest. Rescue of ACK1 expression in the ACK1-knockdown cells suppressed p27 expression and restored cell proliferation. Compared to ACK1-knockdown cells, ACK1-rescued cells exhibited a restored p27 expression after MG132 treatment and showed an elevated level of ubiquitinated p27. Our data further showed that knockdown of ubiquitin ligase Skp2 resulted in elevated p27 expression. Importantly, the expression of p27(WT), p27(Y74F), or p27(Y89F) in ACK1-overexpressed 293T cells or ACK1-rescued SAS cells showed higher levels of tyrosyl-phosphorylated p27 and interaction with ACK1 or Skp2. However, the expression of p27(Y88F) mutant exhibited a relatively low phosphorylation level and barely bound with ACK1 or Skp2, showing a basal interaction as the control cells. These results suggested that ACK1 is highly expressed in HNSCC tumors and functions to promote cell proliferation by the phosphorylation and degradation of p27 in the Skp2-mediated mechanism.
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Affiliation(s)
- Hsuan-Hsiang Peng
- grid.260567.00000 0000 8964 3950Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301 Taiwan, Republic of China
| | - Hao-Chin Yang
- grid.260567.00000 0000 8964 3950Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301 Taiwan, Republic of China
| | - Darius Rupa
- grid.260567.00000 0000 8964 3950Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301 Taiwan, Republic of China
| | - Chun-Han Yen
- grid.260567.00000 0000 8964 3950Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301 Taiwan, Republic of China
| | - Ya-Wen Chiu
- grid.260567.00000 0000 8964 3950Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301 Taiwan, Republic of China
| | - Wei-Jia Yang
- grid.415323.20000 0004 0639 3300Department of Pathology, Mennonite Christian Hospital, Hualien, 970 Taiwan, Republic of China
| | - Fuh-Jinn Luo
- grid.415323.20000 0004 0639 3300Department of Pathology, Mennonite Christian Hospital, Hualien, 970 Taiwan, Republic of China
| | - Ta-Chun Yuan
- grid.260567.00000 0000 8964 3950Department of Life Science, National Dong Hwa University, No. 1, Sec. 2, Da Hsueh Rd., Shoufeng, Hualien, 974301 Taiwan, Republic of China
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He C, Wang T, Han Y, Zuo C, Wang G. E3 ubiquitin ligase COP1 confers neuroprotection in cerebral ischemia/reperfusion injury via regulation of transcription factor C/EBPβ in microglia. Int J Biol Macromol 2022; 222:1789-1800. [DOI: 10.1016/j.ijbiomac.2022.09.264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 09/01/2022] [Accepted: 09/28/2022] [Indexed: 11/05/2022]
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Jung SY, Yun HH, Lim JH, Lee DH, Seo SB, Baek JY, Lee J, Yoo K, Kim H, Kim HL, Lee JH. Hepatocyte-specific deletion of Bis causes senescence in the liver without deteriorating hepatic function. Biochem Biophys Res Commun 2022; 619:42-48. [PMID: 35732079 DOI: 10.1016/j.bbrc.2022.06.046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/11/2022] [Accepted: 06/14/2022] [Indexed: 11/02/2022]
Abstract
Bcl-2-interacting cell death suppressor (BIS), also called as BAG3, regulates numerous physiological processes, such as apoptosis, protein quality control, and senescence. Whole-body Bis-knockout (KO) mice exhibit early lethality following cardiac and skeletal muscle dysfunction. The first attempt to generate organ-specific knockout mice resulted in constitutive or inducible heart-specific Bis-knockout mice, which exhibited cardiac dilation and underwent premature death. Here, we generated hepatocyte-specific Bis-knockout (Bis-HKO) mice and found no abnormalities in metabolic function and survival. However, depletion of HSPB8 and accumulation of p62 indicated impaired autophagy in Bis-HKO livers. Interestingly, the number of peroxisomes wrapped by phagophore membranes increased as evidenced by transmission electron microscopy analysis, indicating defects in the progression of pexophagy. In addition, increased dihydroethidine intensities and histone H3 K9me3-positive nuclei indicated increased oxidative stress and senescence induction in Bis-HKO livers. Mechanistically, p27 was upregulated in Bis-HKO livers. In SNU368 hepatocellular carcinoma cells, BIS depletion led to p27 upregulation, and increase in histone H3 K9me3 levels and senescence-associated β-galactosidase staining; therefore, reproducing the in vivo senescence phenotype. Despite the observation of no metabolic abnormalities, BIS depletion led to defective autophagy, increased oxidative stress, and senescence in Bis-HKO livers. Collectively, our results suggest a role for BIS in maintaining liver regeneration potential under pathological conditions.
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Affiliation(s)
- Soon-Young Jung
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Hye Hyeon Yun
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Ji Hee Lim
- Division of Nephrology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Dong-Hyung Lee
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Sung Bin Seo
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Ji-Ye Baek
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Jeehan Lee
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Kyunghyun Yoo
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Hyungmin Kim
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Hong Lim Kim
- Integrative Research Support Center, Laboratory of Electron Microscope, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea
| | - Jeong-Hwa Lee
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea; Institute for Aging and Metabolic Diseases, College of Medicine, The Catholic University of Korea, Seoul, 06591, South Korea.
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COP1 Acts as a Ubiquitin Ligase for PCDH9 Ubiquitination and Degradation in Human Glioma. Mol Neurobiol 2022; 59:2378-2388. [PMID: 35084653 DOI: 10.1007/s12035-021-02634-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 11/02/2021] [Indexed: 10/19/2022]
Abstract
Constitutive photomorphogenic 1 (COP1, also known as RFWD2), a ring-finger-type E3 ubiquitin ligase, has been reported to play a pivotal role in the regulation of cell growth, apoptosis, and DNA repair. Accumulating evidence has suggested that COP1 plays a role in tumorigenesis by triggering the ubiquitination and degradation of its substrates, but the potential mechanism remains unclear. In this study, COP1 was used as a bait in a yeast two-hybrid experiment to screen COP1-interacting proteins in a human brain cDNA library, and the results indicated that protocadherin 9 (PCDH9) was a potential binding protein of COP1. The interaction between and colocalization of COP1 and PCDH9 was further confirmed by coimmunoprecipitation (co-IP) assay and immunofluorescent staining. Subsequently, we demonstrated that COP1 acted as an E3 ligase to promote the ubiquitination and degradation of PCDH9 through the proteasome pathway in glioma cells. Furthermore, we identified that the type of COP1 mediated PCDH9 ubiquitination was Lys48-linked polyubiquitination. Finally, we found that the COP1 protein level was inversely correlated with the PCDH9 protein level in human glioma tissues. Taken together, our results suggest that COP1 is an E3 ubiquitin ligase for PCDH9 and reveal an important mechanism for PCDH9 regulation in human glioma.
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[Effects of ring finger and tryptophan-aspartic acid 2 on dendritic spines and synapse formation in cerebral cortex neurons of mice]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2022; 42:78-85. [PMID: 35249873 PMCID: PMC8901395 DOI: 10.12122/j.issn.1673-4254.2022.01.09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE To clarify the functional effects of differential expression of ring finger and tryptophan-aspartic acid 2 (RFWD2) on dendritic development and formation of dendritic spines in cerebral cortex neurons of mice. METHODS Immunofluorescent staining was used to identify the location and global expression profile of RFWD2 in mouse brain and determine the co-localization of RFWD2 with the synaptic proteins in the cortical neurons. We also examined the effects of RFWD2 over-expression (RFWD2-Myc) and RFWD2 knockdown (RFWD2-shRNA) on dendritic development, dendritic spine formation and synaptic function in cultured cortical neurons. RESULTS RFWD2 is highly expressed in the cerebral cortex and hippocampus of mice, and its expression level was positively correlated with the development of cerebral cortex neurons and dendrites. RFWD2 expression was detected on the presynaptic membrane and postsynaptic membrane of the neurons, and its expression levels were positively correlated with the length, number of branches and complexity of the dendrites. In cultured cortical neurons, RFWD2 overexpression significantly lowered the expressions of the synaptic proteins synaptophysin (P < 0.01) and postsynapic density protein 95 (P < 0.01), while RFWD2 knockdown significantly increased their expressions (both P < 0.05). Compared with the control and RFWD2-overexpressing cells, the neurons with RFWD2 knockdown showed significantly reduced number of dendritic spines (both P < 0.05). CONCLUSION RFWD2 can regulate the expression of the synaptic proteins, the development of the dendrites, the formation of the dendritic spines and synaptic function in mouse cerebral cortex neurons through ubiquitination of Pea3 family members and c-Jun, which may serve as potential treatment targets for neurological diseases.
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The Involvement of Ubiquitination Machinery in Cell Cycle Regulation and Cancer Progression. Int J Mol Sci 2021; 22:ijms22115754. [PMID: 34072267 PMCID: PMC8198665 DOI: 10.3390/ijms22115754] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/12/2021] [Accepted: 05/26/2021] [Indexed: 02/07/2023] Open
Abstract
The cell cycle is a collection of events by which cellular components such as genetic materials and cytoplasmic components are accurately divided into two daughter cells. The cell cycle transition is primarily driven by the activation of cyclin-dependent kinases (CDKs), which activities are regulated by the ubiquitin-mediated proteolysis of key regulators such as cyclins, CDK inhibitors (CKIs), other kinases and phosphatases. Thus, the ubiquitin-proteasome system (UPS) plays a pivotal role in the regulation of the cell cycle progression via recognition, interaction, and ubiquitination or deubiquitination of key proteins. The illegitimate degradation of tumor suppressor or abnormally high accumulation of oncoproteins often results in deregulation of cell proliferation, genomic instability, and cancer occurrence. In this review, we demonstrate the diversity and complexity of the regulation of UPS machinery of the cell cycle. A profound understanding of the ubiquitination machinery will provide new insights into the regulation of the cell cycle transition, cancer treatment, and the development of anti-cancer drugs.
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Guo M, Ding P, Zhu Z, Fan L, Zhou Y, Yang S, Yang Y, Gu C. Targeting RFWD2 as an Effective Strategy to Inhibit Cellular Proliferation and Overcome Drug Resistance to Proteasome Inhibitor in Multiple Myeloma. Front Cell Dev Biol 2021; 9:675939. [PMID: 33968945 PMCID: PMC8097052 DOI: 10.3389/fcell.2021.675939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 03/30/2021] [Indexed: 12/15/2022] Open
Abstract
The potential to overcome resistance to proteasome inhibitors is greatly related with ubiquitin-proteasome system during multiple myeloma (MM) treatment process. The constitutive photomorphogenic 1 (RFWD2), referred to an E3 ubiquitin ligase, has been identified as an oncogene in multiple cancers, yet important questions on the role of RFWD2 in MM biology and treatment remain unclear. Here we demonstrated that MM patients with elevated RFWD2 expression achieved adverse outcome and drug resistance by analyzing gene expression profiling. Moreover, we proved that RFWD2 participated in the process of cell cycle, cell growth and death in MM by mass spectrometry analysis. In vitro study indicated that inducible knockdown of RFWD2 hindered cellular growth and triggered apoptosis in MM cells. Mechanism study revealed that RFWD2 controlled MM cellular proliferation via regulating the degradation of P27 rather than P53. Further exploration unveiled that RFWD2 meditated P27 ubiquitination via interacting with RCHY1, which served as an E3 ubiquitin ligase of P27. Finally, in vivo study illustrated that blocking RFWD2 in BTZ-resistant MM cells overcame the drug resistance in a myeloma xenograft mouse model. Taken together, these findings provide compelling evidence for prompting that targeting RFWD2 may be an effective strategy to inhibit cellular proliferation and overcome drug resistance to proteasome inhibitor in MM.
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Affiliation(s)
- Mengjie Guo
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China.,Large Data Center, Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, China
| | - Pinggang Ding
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Zhen Zhu
- College of Health and Rehabilitation & College of Acupuncture and Massage, Nanjing University of Chinese Medicine, Nanjing, China
| | - Lu Fan
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yanyan Zhou
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Shu Yang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Ye Yang
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China
| | - Chunyan Gu
- School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China.,Large Data Center, Nanjing Hospital of Chinese Medicine affiliated to Nanjing University of Chinese Medicine, Nanjing, China
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Hou J, Cui H. CSN6: a promising target for cancer prevention and therapy. Histol Histopathol 2020; 35:645-652. [PMID: 32016946 DOI: 10.14670/hh-18-206] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
CSN6 has recently received increased attention as a multifunctional protein involved in protein stability. CSN6 plays an important role in controlling cellular proliferation, apoptosis and metastasis, modulating signal transduction, as well as regulating DNA damage and repair. Most studies have demonstrated that CSN6 is significantly upregulated in human malignant tumors such as cervical cancer, papillary thyroid cancer, colorectal cancer, breast cancer, lung adenocarcinoma, and glioblastoma, and its expression is usually correlated with poor prognosis. In this review, we summarize recent available findings regarding the oncogenic role of CSN6 in tumors, and provide a better understanding of CSN6 function at the molecular level and its potential therapeutic implications in combating human cancers.
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Affiliation(s)
- Jianbing Hou
- State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Biotechnology, Southwest University, Chongqing, China.,Cancer Center, Medical Research Institute, Southwest University, Chongqing, China.,Chongqing Engineering and Technology Research Centre for Silk Biomaterials and Regenerative Medicine, Chongqing, China
| | - Hongjuan Cui
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China.,Chongqing Engineering and Technology Research Centre for Silk Biomaterials and Regenerative Medicine, Chongqing, China.,State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, College of Biotechnology, Southwest University, Chongqing, China.
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Song Y, Liu Y, Pan S, Xie S, Wang ZW, Zhu X. Role of the COP1 protein in cancer development and therapy. Semin Cancer Biol 2020; 67:43-52. [PMID: 32027978 DOI: 10.1016/j.semcancer.2020.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 01/29/2020] [Accepted: 02/01/2020] [Indexed: 12/31/2022]
Abstract
COP1, an E3 ubiquitin ligase, has been demonstrated to play a vital role in the regulation of cell proliferation, apoptosis and DNA repair. Accumulated evidence has revealed that COP1 is involved in carcinogenesis via targeting its substrates, including p53, c-Jun, ETS, β-catenin, STAT3, MTA1, p27, 14-3-3σ, and C/EBPα, for ubiquitination and degradation. COP1 can play tumor suppressive and oncogenic roles in human malignancies, urging us to summarize the functions of COP1 in tumorigenesis. In this review, we describe the structure of COP1 and its known substrates. Moreover, we dissect the function of COP1 by physiological (mouse models), pathological (human tumor specimens) and biochemical (ubiquitin substrates) Evidence. Furthermore, we discuss COP1 as a potential therapeutic target for cancer therapy.
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Affiliation(s)
- Yizuo Song
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, China
| | - Yi Liu
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, China
| | - Shuya Pan
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, China
| | - Shangdan Xie
- Department of Obstetrics and Gynecology, The Second Affiliated Hospital of Wenzhou Medical University, Wenzhou, 325027, Zhejiang, China
| | - Zhi-Wei Wang
- Center of Scientific Research, The Second Affiliated Hospital of Wenzhou Medical University, 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, Wenzhou, 325027, Zhejiang, China.
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Mobini K, Banakar E, Tamaddon G, Mohammadi-Bardbori A. 6-Formylindolo[3,2-b]carbazole (FICZ) Enhances The Expression of Tumor Suppressor miRNAs, miR-22, miR-515-5p, and miR-124-3p in MCF-7 Cells. CELL JOURNAL 2019; 22:115-120. [PMID: 31606975 PMCID: PMC6791069 DOI: 10.22074/cellj.2020.6549] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 02/21/2019] [Indexed: 11/22/2022]
Abstract
Objective microRNAs (miRNAs) play bifunctional roles in the initiation and progression of cancer, and recent evidence
has confirmed that unusual expression of miRNAs is required for the progress of breast cancer. The regulatory role of
aryl hydrocarbon receptor (AhR) and its endogenous ligand, 6-formylindolo[3,2-b]carbazole (FICZ) on the expression
of tumor suppressor miRNAs, miR-22, miR-515-5p and miR-124-3p, as well as their association with the estrogen
receptor alpha (ERα) were the aims of this study.
Materials and Methods In this experimental study, the expression levels of miR-22, miR-515-5p, miR-124-3p and
miR-382-5p in MCF-7 cells were determined using the quantificational real time polymerase chain reaction (qRT-PCR)
assay.
Results Our results revealed that miR-22, miR-515-5p, and miR-124-3p expressions were significantly increased in
cells transfected with ERα siRNA. Our data also showed that miR-22, miR 515-5p, and miR-124-3p expression levels
were significantly increased following FICZ treatment. Here, we found that AhR/ERα cross-talk plays a critical role in
the expression of miR-22, miR-515-5p and miR-124-3p in MCF-7 cells.
Conclusion Overall, our data demonstrated that FICZ, as an AhR agonist could induce the expression of tumor
suppressor miRNAs, miR-22, miR-515-5p, and miR-124-3p; thus, FICZ might be regarded as a potential therapeutic
agent for breast cancer treatment.
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Affiliation(s)
- Keivan Mobini
- Department of Pharmacology and Toxicology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Elham Banakar
- Department of Pharmacology and Toxicology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Gholamhossein Tamaddon
- Diagnostic Laboratory Sciences and Technology Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Afshin Mohammadi-Bardbori
- Department of Pharmacology and Toxicology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.ElectronicAddress:
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13
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Chou CF, Hsieh YH, Grubbs CJ, Atigadda VR, Mobley JA, Dummer R, Muccio DD, Eto I, Elmets CA, Garvey WT, Chang PL. The retinoid X receptor agonist, 9-cis UAB30, inhibits cutaneous T-cell lymphoma proliferation through the SKP2-p27kip1 axis. J Dermatol Sci 2018; 90:343-356. [PMID: 29599065 PMCID: PMC6329374 DOI: 10.1016/j.jdermsci.2018.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 02/15/2018] [Accepted: 03/08/2018] [Indexed: 01/09/2023]
Abstract
BACKGROUND Bexarotene (Targretin®) is currently the only FDA approved retinoid X receptor (RXR) -selective agonist for the treatment of cutaneous T-cell lymphomas (CTCLs). The main side effects of bexarotene are hypothyroidism and elevation of serum triglycerides (TGs). The novel RXR ligand, 9-cis UAB30 (UAB30) does not elevate serum TGs or induce hypothyroidism in normal subjects. OBJECTIVES To assess preclinical efficacy and mechanism of action of UAB30 in the treatment of CTCLs and compare its action with bexarotene. METHODS With patient-derived CTCL cell lines, we evaluated UAB30 function in regulating growth, apoptosis, cell cycle check points, and cell cycle-related markers. RESULTS Compared to bexarotene, UAB30 had lower half maximal inhibitory concentration (IC50) values and was more effective in inhibiting the G1 cell cycle checkpoint. Both rexinoids increased the stability of the cell cycle inhibitor, p27kip1 protein, in part, through targeting components involved in the ubiquitination-proteasome system: 1) decreasing SKP2, a F-box protein that binds and targets p27kip1 for degradation by 26S proteasome and 2) suppressing 20S proteasome activity (cell line-dependent) through downregulation of PSMA7, a component of the 20S proteolytic complex in 26S proteasome. CONCLUSIONS UAB30 and bexarotene induce both early cell apoptosis and suppress cell proliferation. Inhibition of the G1 to S cell cycle transition by rexinoids is mediated, in part, through downregulation of SKP2 and/or 20S proteasome activity, leading to increased p27kip1 protein stability. Because UAB30 has minimal effect in elevating serum TGs and inducing hypothyroidism, it is potentially a better alternative to bexarotene for the treatment of CTCLs.
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Affiliation(s)
- Chu-Fang Chou
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Yu-Hua Hsieh
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Clinton J Grubbs
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Venkatram R Atigadda
- Department of Dermatology, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - James A Mobley
- Department of Surgery, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Reinhard Dummer
- Department of Dermatology, University Hospital of Zurich, Switzerland
| | - Donald D Muccio
- Department of Biochemistry, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Isao Eto
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Craig A Elmets
- Department of Dermatology, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - W Timothy Garvey
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA
| | - Pi-Ling Chang
- Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA; Department of Dermatology, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA; Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA.
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14
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Ka WH, Cho SK, Chun BN, Byun SY, Ahn JC. The ubiquitin ligase COP1 regulates cell cycle and apoptosis by affecting p53 function in human breast cancer cell lines. Breast Cancer 2018. [PMID: 29516369 DOI: 10.1007/s12282-018-0849-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND The E3 ubiquitin ligase constitutive photomorphogenic 1 (COP1) mediates cell survival, growth, and development, and interacts with the tumor suppressor protein p53 to induce its ubiquitination and degradation. Recent studies reported that COP1 overexpression is associated with increased cell proliferation, transformation, and disease progression in a variety of cancer types. In this study, we investigated whether COP1 regulates p53-mediated cell cycle arrest and apoptosis in human breast cancer cell lines. METHODS We downregulated COP1 expression using lentiviral particles expressing short hairpin RNA (shRNA) targeting COP1 and measured the effects of the knockdown in three different breast cancer cell lines. RESULTS COP1 silencing resulted in p53 activation, which induced the expression of p21 and p53-upregulated modulator of apoptosis (PUMA) expression, and reduced the levels of cyclin-dependent kinase 2 (CDK2). Notably, knockdown of COP1 was associated with cell cycle arrest during the G0/G1 phase. CONCLUSIONS The COP1-mediated degradation of p53 regulates cancer cell growth and apoptosis. Our results indicate that COP1 regulates human breast cancer cell proliferation and apoptosis in a p53-dependent manner. These findings suggest that COP1 might be a promising potential target for breast cancer-related gene therapy.
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Affiliation(s)
- Won Hye Ka
- WJ R&D Center, WOOJUNG BSC, Advanced Institutes of Convergence Technology, 145 Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 443-270, Republic of Korea
- Applied Biotechnology Department, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon, 16499, Republic of Korea
| | - Seok Keun Cho
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul, 03722, Republic of Korea
| | - Byung Nyun Chun
- WJ R&D Center, WOOJUNG BSC, Advanced Institutes of Convergence Technology, 145 Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 443-270, Republic of Korea
| | - Sang Yo Byun
- Applied Biotechnology Department, Ajou University, 206 Worldcup-ro, Yeongtong-gu, Suwon, 16499, Republic of Korea.
| | - Jong Cheol Ahn
- WJ R&D Center, WOOJUNG BSC, Advanced Institutes of Convergence Technology, 145 Gwanggyo-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 443-270, Republic of Korea.
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15
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Feng T, Shao F, Wu Q, Zhang X, Xu D, Qian K, Xie Y, Wang S, Xu N, Wang Y, Qi C. miR-124 downregulation leads to breast cancer progression via LncRNA-MALAT1 regulation and CDK4/E2F1 signal activation. Oncotarget 2017; 7:16205-16. [PMID: 26918449 PMCID: PMC4941308 DOI: 10.18632/oncotarget.7578] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Accepted: 02/05/2016] [Indexed: 12/28/2022] Open
Abstract
The long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been recently shown to be dysregulated in several cancers. However, the mechanisms underlying the role of MALAT1 in breast cancer remain unclear. Herein, we showed that MALAT1 was aberrantly increased in breast cancer tissues and cells. MALAT1-siRNA inhibited breast cancer cell proliferation and cell cycle progression in vitro and in vivo. Furthermore, MALAT1 acted as an endogenous potent regulator by directly binding to miR-124 and down-regulating miR-124 expression. In addition, MALAT1 reversed the inhibitory effect of miR-124 on breast cancer proliferation and was involved in the cyclin-dependent kinase 4 (CDK4) expression. Taken together, our data highlight the pivotal role of MALAT1 in breast cancer tumorigenesis. Moreover, the present study elucidated the MALAT1-miR-124-CDK4/E2F1 signaling pathway in breast cancer, which might provide a new approach for tackling breast cancer.
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Affiliation(s)
- Tongbao Feng
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China.,Department of Oncology, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China.,Department of General Surgery, the Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Fang Shao
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Qiyong Wu
- Department of General Surgery, the Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Xiaohang Zhang
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Dongqin Xu
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Keqing Qian
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China.,Department of Oncology, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Yewen Xie
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China.,Department of Oncology, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Shizhong Wang
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Ning Xu
- Section of Clinical Chemistry and Pharmacology, Department of Laboratory Medicine, Lund University, S-221 85 Lund, Sweden
| | - Yong Wang
- Department of General Surgery, the Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
| | - Chunjian Qi
- Medical Research Center, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China.,Department of Oncology, The Affiliated Hospital of Nanjing Medical University, Changzhou No.2 People's Hospital, Changzhou, 213003, China
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16
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Buuh ZY, Lyu Z, Wang RE. Interrogating the Roles of Post-Translational Modifications of Non-Histone Proteins. J Med Chem 2017; 61:3239-3252. [PMID: 28505447 DOI: 10.1021/acs.jmedchem.6b01817] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Post-translational modifications (PTMs) allot versatility to the biological functions of highly conserved proteins. Recently, modifications to non-histone proteins such as methylation, acetylation, phosphorylation, glycosylation, ubiquitination, and many more have been linked to the regulation of pivotal pathways related to cellular response and stability. Due to the roles these dynamic modifications assume, their dysregulation has been associated with cancer and many other important diseases such as inflammatory disorders and neurodegenerative diseases. For this reason, we present a review and perspective on important post-translational modifications on non-histone proteins, with emphasis on their roles in diseases and small molecule inhibitors developed to target PTM writers. Certain PTMs' contribution to epigenetics has been extensively expounded; yet more efforts will be needed to systematically dissect their roles on non-histone proteins, especially for their relationships with nononcological diseases. Finally, current research approaches for PTM study will be discussed and compared, including limitations and possible improvements.
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Affiliation(s)
- Zakey Yusuf Buuh
- Department of Chemistry , Temple University , 1901 N. 13th Street , Philadelphia , Pennsylvania 19122 , United States
| | - Zhigang Lyu
- Department of Chemistry , Temple University , 1901 N. 13th Street , Philadelphia , Pennsylvania 19122 , United States
| | - Rongsheng E Wang
- Department of Chemistry , Temple University , 1901 N. 13th Street , Philadelphia , Pennsylvania 19122 , United States
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17
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Zhu Y, Wu Y, Shi W, Wang J, Yan X, Wang Q, Liu Y, Yang L, Gao L, Li M. Inhibition of ubiquitin proteasome function prevents monocrotaline-induced pulmonary arterial remodeling. Life Sci 2017; 173:36-42. [PMID: 28212825 DOI: 10.1016/j.lfs.2017.02.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/06/2017] [Accepted: 02/13/2017] [Indexed: 11/28/2022]
Abstract
AIMS Previous study has indicated that inhibition of proteasome function ameliorates the development of pulmonary arterial hypertension (PAH), while its underlying mechanisms are still unclear. This study was performed to address these issues. MATERIAL AND METHODS Male Sprague-Dawley (SD) rats were divided into five groups: control group, PAH group, vehicle treated PAH group, MG-132 treated PAH group and bortezomib treated PAH group. PAH model was established by a single intraperitoneal injection of monocrotaline (MCT). MG-132 and bortezomib were administered to inhibit proteasome function. The right ventricular systolic pressure (RVSP), the right ventricle hypertrophy index (RVHI) and the percentage of medial wall thickness (%MT) were used to evaluate the development of PAH. Hematoxylin and eosin staining was performed to measure vascular remodeling. Immunoblotting was used to determine Akt phosphorylation, expression of PTEN and NEDD4, and the level of ubiquitinated-PTEN protein. KEY FINDINGS MCT increased RVSP, RVHI and %MT in rats, while these changes were suppressed by treatment of PAH rats with MG-132 or bortezomib. In PAH model, expression of PTEN was decreased and phosphorylation of Akt was increased, these were accompanied by an elevation of NEDD4 protein level. Treatment of PAH model with MG-132 or bortezomib increased PTEN expression and accumulation of ubiquitinated-PTEN protein and decreased Akt phosphorylation, while didn't change NEDD4 expression. SIGNIFICANCE Inhibition of proteasome function ameliorates pulmonary arterial remodeling by suppressing UPS-mediated PTEN degradation and subsequent inhibition of PI3K/Akt pathway, indicating that UPS might be a novel target for prevention of PAH.
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Affiliation(s)
- Yanting Zhu
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Yinxia Wu
- Wuhan University of Science and Technology, Wuhan, Hubei 430081, People's Republic of China
| | - Wenhua Shi
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Jian Wang
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Xin Yan
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Qingting Wang
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Ya Liu
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Lan Yang
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China
| | - Li Gao
- Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA
| | - Manxiang Li
- Department of Respiratory Medicine, First Affiliated Hospital of Xi'an JiaoTong University, Xi'an, Shaanxi 710061, People's Republic of China.
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18
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The Ubiquitin Ligase COP1 Promotes Glioma Cell Proliferation by Preferentially Downregulating Tumor Suppressor p53. Mol Neurobiol 2016; 54:5008-5016. [DOI: 10.1007/s12035-016-0033-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 08/01/2016] [Indexed: 12/31/2022]
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19
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Gao S, Fang L, Phan LM, Qdaisat A, Yeung SCJ, Lee MH. COP9 signalosome subunit 6 (CSN6) regulates E6AP/UBE3A in cervical cancer. Oncotarget 2016; 6:28026-41. [PMID: 26318036 PMCID: PMC4695042 DOI: 10.18632/oncotarget.4731] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 07/23/2015] [Indexed: 02/03/2023] Open
Abstract
Cervical cancer is one of the leading causes of cancer death in women. Human papillomaviruses (HPVs) are the major cause in almost 99.7% of cervical cancer. E6 oncoprotein of HPV and E6-associated protein (E6AP) are critical in causing p53 degradation and malignancy. Understanding the E6AP regulation is critical to develop treating strategy for cervical cancer patients. The COP9 signalosome subunit 6 (CSN6) is involved in ubiquitin-mediated protein degradation. We found that both CSN6 and E6AP are overexpressed in cervical cancer. We characterized that CSN6 associated with E6AP and stabilized E6AP expression by reducing E6AP poly-ubiquitination, thereby regulating p53 activity in cell proliferation and apoptosis. Mechanistic studies revealed that CSN6-E6AP axis can be regulated by EGF/Akt signaling. Furthermore, inhibition of CSN6-E6AP axis hinders cervical cancer growth in mice. Taken together, our results indicate that CSN6 is a positive regulator of E6AP and is important for cervical cancer development.
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Affiliation(s)
- Shujun Gao
- Obstetrics and Gynecology Hospital Fudan University, Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai 200011, China.,Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Lekun Fang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of Colorectal Surgery, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China
| | - Liem Minh Phan
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Aiham Qdaisat
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Sai-Ching J Yeung
- Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of Emergency Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA
| | - Mong-Hong Lee
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.,Department of Colorectal Surgery, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou 510655, China.,Program in Cancer Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.,Program in Genes and Development, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA
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20
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Sanchez-Barcelo EJ, Mediavilla MD, Vriend J, Reiter RJ. Constitutive photomorphogenesis protein 1 (COP1) and COP9 signalosome, evolutionarily conserved photomorphogenic proteins as possible targets of melatonin. J Pineal Res 2016; 61:41-51. [PMID: 27121162 DOI: 10.1111/jpi.12340] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 04/26/2016] [Indexed: 12/18/2022]
Abstract
The ubiquitin proteasome system has been proposed as a possible mechanism involved in the multiple actions of melatonin. COP1 (constitutive photomorphogenesis protein 1), a RING finger-type ubiquitin E3 ligase formerly identified in Arabidopsis, is a central switch for the transition from plant growth underground in darkness (etiolation) to growth under light exposure (photomorphogenesis). In darkness, COP1 binds to photomorphogenic transcription factors driving its degradation via the 26S proteasome; blue light, detected by cryptochromes, and red and far-red light detected by phytochromes, negatively regulate COP1. Homologues of plant COP1 containing all the structural features present in Arabidopsis as well as E3 ubiquitin ligase activity have been identified in mice and humans. Substrates for mammalian (m) COP1 include p53, AP-1 and c-Jun, p27(Kip1) , ETV1, MVP, 14-3-3σ, C/EBPα, MTA1, PEA3, ACC, TORC2 and FOXO1. This mCOP1 target suggests functions related to tumorigenesis, gluconeogenesis, and lipid metabolism. The role of mCOP1 in tumorigenesis (either as a tumor promoter or tumor suppressor), as well as in glucose metabolism (inhibition of gluconeogenesis) and lipid metabolism (inhibition of fatty acid synthesis), has been previously demonstrated. COP1, along with numerous other ubiquitin ligases, is regulated by the COP9 signalosome; this protein complex is associated with the oxidative stress sensor Keap1 and the deubiquitinase USP15. The objective of this review was to provide new information on the possible role of COP1 and COP9 as melatonin targets. The hypothesis is based on common functional aspects of melatonin and COP1 and COP9, including their dependence on light, regulation of the metabolism, and their control of tumor growth.
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Affiliation(s)
| | - Maria D Mediavilla
- Department of Physiology and Pharmacology, University of Cantabria, Santander, Spain
| | - Jerry Vriend
- Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, MB, Canada
| | - Russel J Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX, USA
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21
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Structural Basis for Substrate Selectivity of the E3 Ligase COP1. Structure 2016; 24:687-696. [PMID: 27041596 DOI: 10.1016/j.str.2016.03.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/19/2016] [Accepted: 03/04/2016] [Indexed: 12/25/2022]
Abstract
COP1 proteins are E3 ubiquitin ligases that regulate phototropism in plants and target transcription factors for degradation in mammals. The substrate-binding region of COP1 resides within a WD40-repeat domain that also binds to Trib proteins, which are adaptors for C/EBPα degradation. Here we report structures of the human COP1 WD40 domain in isolation, and complexes of the human and Arabidopsis thaliana COP1 WD40 domains with the binding motif of Trib1. The human and Arabidopsis WD40 domains are seven-bladed β propellers with an inserted loop on the bottom face of the first blade. The Trib1 peptide binds in an extended conformation to a highly conserved surface on the top face of the β propeller, indicating a general mode for recognition of peptide motifs by COP1. Together, these studies identify the structural basis and key interactions for motif recognition by COP1, and hint at how Trib1 autoinhibition is overcome to target C/EBPα for degradation.
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22
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Shin J, Phan L, Chen J, Lu Z, Lee MH. CSN6 positively regulates c-Jun in a MEKK1-dependent manner. Cell Cycle 2015; 14:3079-87. [PMID: 26237449 DOI: 10.1080/15384101.2015.1078030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
c-Jun is a proto-oncoprotein that is commonly overexpressed in many types of cancer and is believed to regulate cell proliferation, the cell cycle, and apoptosis by controlling AP-1 activity. Understanding the c-Jun regulation is important to develop treatment strategy for cancer. The COP9 signalosome subunit 6 (CSN6) plays a critical role in ubiquitin-mediated protein degradation. MEKK1 is a serine/threonine kinase and E3 ligase containing PHD/RING domain involved in c-Jun ubiquitination. Here, we show that CSN6 associates with MEKK1 and reduces MEKK1 expression level by facilitating the ubiquitin-mediated degradation of MEKK1. Also we show that CSN6 overexpression diminishes MEKK1-mediated c-Jun ubiquitination, which is manifested in mitigating osmotic stress-mediated c-Jun downregulation. Thus, CSN6 is involved in positively regulating the stability of c-Jun. Overexpression of CSN6 correlates with the upregulation of c-Jun target gene expression in cancer. These findings provide new insight into CSN6-MEKK1-c-Jun axis in tumorigenesis.
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Affiliation(s)
- Jihyun Shin
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Liem Phan
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Jian Chen
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Zhimin Lu
- b Molecular pathology; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
| | - Mong-Hong Lee
- a Departments of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
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23
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Phan L, Chou PC, Velazquez-Torres G, Samudio I, Parreno K, Huang Y, Tseng C, Vu T, Gully C, Su CH, Wang E, Chen J, Choi HH, Fuentes-Mattei E, Shin JH, Shiang C, Grabiner B, Blonska M, Skerl S, Shao Y, Cody D, Delacerda J, Kingsley C, Webb D, Carlock C, Zhou Z, Hsieh YC, Lee J, Elliott A, Ramirez M, Bankson J, Hazle J, Wang Y, Li L, Weng S, Rizk N, Wen YY, Lin X, Wang H, Wang H, Zhang A, Xia X, Wu Y, Habra M, Yang W, Pusztai L, Yeung SC, Lee MH. The cell cycle regulator 14-3-3σ opposes and reverses cancer metabolic reprogramming. Nat Commun 2015; 6:7530. [PMID: 26179207 PMCID: PMC4507299 DOI: 10.1038/ncomms8530] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/18/2015] [Indexed: 12/16/2022] Open
Abstract
Extensive reprogramming of cellular energy metabolism is a hallmark of cancer. Despite its importance, the molecular mechanism controlling this tumour metabolic shift remains not fully understood. Here we show that 14-3-3σ regulates cancer metabolic reprogramming and protects cells from tumorigenic transformation. 14-3-3σ opposes tumour-promoting metabolic programmes by enhancing c-Myc poly-ubiquitination and subsequent degradation. 14-3-3σ demonstrates the suppressive impact on cancer glycolysis, glutaminolysis, mitochondrial biogenesis and other major metabolic processes of tumours. Importantly, 14-3-3σ expression levels predict overall and recurrence-free survival rates, tumour glucose uptake and metabolic gene expression in breast cancer patients. Thus, these results highlight that 14-3-3σ is an important regulator of tumour metabolism, and loss of 14-3-3σ expression is critical for cancer metabolic reprogramming. We anticipate that pharmacologically elevating the function of 14-3-3σ in tumours could be a promising direction for targeted anticancer metabolism therapy development in future.
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Affiliation(s)
- Liem Phan
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Ping-Chieh Chou
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Guermarie Velazquez-Torres
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Ismael Samudio
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Kenneth Parreno
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yaling Huang
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Chieh Tseng
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Thuy Vu
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Chris Gully
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Chun-Hui Su
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Edward Wang
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Jian Chen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hyun-Ho Choi
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Enrique Fuentes-Mattei
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ji-Hyun Shin
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Christine Shiang
- 1] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA. [2] Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Brian Grabiner
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Marzenna Blonska
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Stephen Skerl
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yiping Shao
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Dianna Cody
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jorge Delacerda
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Charles Kingsley
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Douglas Webb
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Colin Carlock
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
| | - Zhongguo Zhou
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yun-Chih Hsieh
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jaehyuk Lee
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrew Elliott
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Marc Ramirez
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jim Bankson
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - John Hazle
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yongxing Wang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lei Li
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Shaofan Weng
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Nibal Rizk
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yu Ye Wen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Xin Lin
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Hua Wang
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Huamin Wang
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Aijun Zhang
- Methodist Hospital Research Institute, Houston, TX 77030, USA
| | - Xuefeng Xia
- Methodist Hospital Research Institute, Houston, TX 77030, USA
| | - Yun Wu
- Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mouhammed Habra
- Department of Endocrinology Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Wei Yang
- Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lajos Pusztai
- Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sai-Ching Yeung
- 1] Department of Endocrinology Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Department of Emergency Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Mong-Hong Lee
- 1] Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA. [2] Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX 77030, USA
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Choi HH, Guma S, Fang L, Phan L, Ivan C, Baggerly K, Sood A, Lee MH. Regulating the stability and localization of CDK inhibitor p27(Kip1) via CSN6-COP1 axis. Cell Cycle 2015; 14:2265-73. [PMID: 25945542 DOI: 10.1080/15384101.2015.1046655] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The COP9 signalosome subunit 6 (CSN6), which is involved in ubiquitin-mediated protein degradation, is overexpressed in many types of cancer. CSN6 is critical in causing p53 degradation and malignancy, but its target in cell cycle progression is not fully characterized. Constitutive photomorphogenic 1 (COP1) is an E3 ubiquitin ligase associating with COP9 signalosome to regulate important target proteins for cell growth. p27 is a critical G1 CDK inhibitor involved in cell cycle regulation, but its upstream regulators are not fully characterized. Here, we show that the CSN6-COP1 link is regulating p27(Kip1) stability, and that COP1 is a negative regulator of p27(Kip1). Ectopic expression of CSN6 can decrease the expression of p27(Kip1), while CSN6 knockdown leads to p27(Kip1) stabilization. Mechanistic studies show that CSN6 interacts with p27(Kip1) and facilitates ubiquitin-mediated degradation of p27(Kip1). CSN6-mediated p27 degradation depends on the nuclear export of p27(Kip1), which is regulated through COP1 nuclear exporting signal. COP1 overexpression leads to the cytoplasmic distribution of p27, thereby accelerating p27 degradation. Importantly, the negative impact of COP1 on p27 stability contributes to elevating expression of genes that are suppressed through p27 mediation. Kaplan-Meier analysis of tumor samples demonstrates that high COP1 expression was associated with poor overall survival. These data suggest that tumors with CSN6/COP1 deregulation may have growth advantage by regulating p27 degradation and subsequent impact on p27 targeted genes.
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Affiliation(s)
- Hyun Ho Choi
- a Department of Molecular and Cellular Oncology ; The University of Texas MD Anderson Cancer Center ; Houston , TX USA
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