1
|
Zhang C, Wang J, Wang H, Li J. Interference of the Circular RNA Sperm Antigen With Calponin Homology and Coiled-Coil Domains 1 Suppresses Growth and Promotes Apoptosis of Breast Cancer Cells Partially Through Targeting miR-1236-3p/Chromobox 8 Pathway. Clin Breast Cancer 2024; 24:e138-e151.e2. [PMID: 38341369 DOI: 10.1016/j.clbc.2023.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/12/2023] [Accepted: 11/28/2023] [Indexed: 02/12/2024]
Abstract
Noncoding RNAs and RNA modifiers are implicated in cancer radiotherapy. Here, we aimed to investigate the role of sperm antigen with calponin homology and coiled-coil domains 1 (SPECC1)-derived circular RNA (circSPECC1; hsa_circ_0000745) in breast cancer (BC) cells under radiation treatment. Based on quantitative real-time PCR, circSPECC1 was highly upregulated in BC patients' tumors and cells, and circSPECC1 expression was further increased with the dosage of radiation in BC cells. Moreover, circSPECC1 upregulation was found to be concomitant with higher chromobox 8 (CBX8) and lower microRNA (miR)-1236-3p expression. Functionally, 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU) and colony formation assays showed that circSPECC1 interference suppressed cell proliferation and long-term survival in BC cells and irradiated BC cells. Xenograft tumor model experiments showed that circSPECC1 knockdown restrained BC tumor growth in vivo. Meanwhile, flow cytometry assay and western blotting revealed an enhanced apoptosis by silencing circSPECC1. Moreover, miR-1236-3p overexpression, similar to circSPECC1 silencing, displayed anti-growth and proapoptosis roles in irradiated BC cells. Mechanistically, dual-luciferase reporter assay and RNA immunoprecipitation assay identified a target relationship between miR-1236-3p and circSPECC1 or CBX8. Also, CBX8 expression could be modulated by circSPECC1 via miR-1236-3p regulation. Collectively, we indicated that inhibiting circSPECC1 could suppress growth and promote apoptosis of BC cells in both irradiated and nonirradiated conditions at least partially via miR-1236-3p/CBX8 axis, confirming that circSPECC1 might be target to develop anticancer drug in BC.
Collapse
Affiliation(s)
- Cuipeng Zhang
- Department of Oncology, Second Affiliated Hospital of Guizhou Medical University, Guizhou Province, China.
| | - Jing Wang
- Department of Oncology, The Second People's Hospital of Liaocheng, Linqing, Shandong Province, China
| | - Hongwei Wang
- Department of Oncology, Lianyungang No. 2 Hospital of Jiangsu Province, China
| | - Jing Li
- Department of Oncology, Shandong Energy Zaozhuang Mining Group Central Hospital, China
| |
Collapse
|
2
|
Cai X, Lv Y, Pan J, Cao Z, Zhang J, Li Y, Zheng H. CBX8 Promotes Epithelial-mesenchymal Transition, Migration, and Invasion of Lung Cancer through Wnt/β-catenin Signaling Pathway. Curr Protein Pept Sci 2024; 25:CPPS-EPUB-137648. [PMID: 38265409 DOI: 10.2174/0113892037273375231204080906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 01/25/2024]
Abstract
BACKGROUND Lung cancer (LC) is primarily responsible for cancer-related deaths worldwide. Epithelial-mesenchymal transition (EMT) is a process in which epithelial cells acquire mesenchymal features and is associated with the development of tumors. CBX8, a member of the PcG protein family, plays a critical role in various cancers, containing LC. However, specific regulatory mechanisms of CBX8 in LC progression are not fully understood. This study aimed to investigate the regulatory role of CBX8 in LC progression. METHOD Bioinformatics was used to analyze the relationship between CBX8 level and tumor and the enrichment pathway of CBX8 enrichment. qRT-PCR was used to detect the differential expression of CBX8 in LC cells and normal lung epithelial cells. The effects of knockdown or overexpression of CBX8 on the proliferation, migration and invasion of LC cells were evaluated by CCK- -8 assay and Transwell assay, and the levels of proteins associated with the EMT pathway and Wnt/β-catenin signaling pathway were detected by western blot. RESULT Bioinformatics analysis revealed that CBX8 was highly expressed in LC and enriched on the Wnt/β-catenin signaling pathway. The expression level of CBX8 was significantly elevated in LC cells. Knockdown of CBX8 significantly inhibited cell proliferation, migration and invasion, and decreased the expression levels of EMT-related proteins and Wnt/β-catenin pathway-related proteins. Conversely, overexpression of CBX8 promoted cell proliferation, migration and invasion, and increased the expression levels of EMT-related proteins and Wnt/β-catenin pathway-related proteins. The Wnt inhibitor IWP-4 alleviated the effects produced by overexpression of CBX8. CONCLUSION Collectively, these data demonstrated that CBX8 induced EMT through Wnt/β-- catenin signaling, driving migration and invasion of LC cells.
Collapse
Affiliation(s)
- Xiaoping Cai
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| | - Yuankai Lv
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| | - Jiongwei Pan
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| | - Zhuo Cao
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| | - Junzhi Zhang
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| | - Yuling Li
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| | - Hao Zheng
- Department of Respiratory, Six affiliated Hospital of Wenzhou Medical University, Lishui People's Hospital, Lishui 323000, China
| |
Collapse
|
3
|
Zhang F, Zhu T, Wu C, Shen D, Liu L, Chen X, Guan Y, Ding H, Tong X. TRIM28 recruits E2F1 to regulate CBX8-mediated cell proliferation and tumor metastasis of ovarian cancer. Hum Cell 2023; 36:2113-2128. [PMID: 37709991 DOI: 10.1007/s13577-023-00983-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/03/2023] [Indexed: 09/16/2023]
Abstract
Chromobox protein homolog 8 (CBX8) is a transcriptional suppressor participated in various cancers. However, the function and mechanism of CBX8 in the progression of ovarian cancer (OC) are unclear. In this study, we found that CBX8 was upregulated in OC tissues originating from GEPIA and TNM databases, OC patients' samples from hospital, and OC cell lines. Furthermore, CBX8 knockdown by short hairpin RNA (shRNA) technology markedly inhibited proliferation and invasion, induced migration, cell cycle arrest, and apoptosis in vitro. Mechanistically, CBX8 activated PI3K/AKT/mTOR signaling pathway to take effect. In addition, TRIM28 and E2F1 were enriched in OC tissues from the TNM database and OC patients' samples similar to the results of CBX8. Correlation analysis indicated positive correlations among TRIM28, E2F1, and CBX8. E2F1 was proved to bind to the promoter regions of CBX8 and TRIM28, while TRIM28 recruited E2F1 to increase the expression of CBX8 to further increase cell viability, proliferation, and invasion, and decrease migration, apoptosis, and cell cycle progression. Finally, CBX8 or TRIM28 knockdown repressed tumor growth and metastasis of OC in vivo. Therefore, our study showed that the promoting effect of CBX8 on tumor growth and metastasis of OC was participated in the PI3K/AKT/mTOR signaling, TRIM28 and E2F1. Our findings suggested that CBX8 could serve as a potential marker and therapeutic target for OC patients.
Collapse
Affiliation(s)
- Fubin Zhang
- Department of Obstetrics and Gynecology, Tongji Hospital, School of Medicine, Tongji University, No. 389 Xincun Road, Shanghai, 200065, China
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Ningbo University, No. 59 Liuting Street, Ningbo, 315010, Zhejiang Province, China
| | - Tianhong Zhu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Ningbo University, No. 59 Liuting Street, Ningbo, 315010, Zhejiang Province, China
| | - Chenghao Wu
- Department of Obstetrics and Gynecology, Tongji Hospital, School of Medicine, Tongji University, No. 389 Xincun Road, Shanghai, 200065, China
| | - Dongsheng Shen
- Department of Obstetrics and Gynecology, Tongji Hospital, School of Medicine, Tongji University, No. 389 Xincun Road, Shanghai, 200065, China
| | - Lixiao Liu
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Ningbo University, No. 59 Liuting Street, Ningbo, 315010, Zhejiang Province, China
| | - Xueqin Chen
- Department of Traditional Medicine, The First Affiliated Hospital of Ningbo University, No. 59 Liuting Street, Ningbo, 315010, Zhejiang Province, China
| | - Yutao Guan
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Ningbo University, No. 59 Liuting Street, Ningbo, 315010, Zhejiang Province, China.
| | - Huiqing Ding
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Ningbo University, No. 59 Liuting Street, Ningbo, 315010, Zhejiang Province, China.
| | - Xiaowen Tong
- Department of Obstetrics and Gynecology, Tongji Hospital, School of Medicine, Tongji University, No. 389 Xincun Road, Shanghai, 200065, China.
| |
Collapse
|
4
|
Chen H, Su Y, Yang L, Xi L, Li X, Lan B, Liu M, Xuan C. CBX8 promotes lung adenocarcinoma growth and metastasis through transcriptional repression of CDKN2C and SCEL. J Cell Physiol 2023; 238:2710-2723. [PMID: 37733753 DOI: 10.1002/jcp.31124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/28/2023] [Accepted: 09/07/2023] [Indexed: 09/23/2023]
Abstract
Dysregulation of polycomb group (PcG) proteins that mediate epigenetic gene silencing contributes to tumorigenesis. As core components of the polycomb repressive complex 1 (PRC1), chromobox (CBX) proteins recognize H3K27me3 to recruit PRC1 to maintain a repressive transcriptional state. However, the individual biological functions of these CBX proteins in tumorigenesis warrant in-depth investigation. In this study, we analyzed the mRNA expression of CBX family genes across multiple cancers using The Cancer Genome Atlas data and found different expression patterns of the five CBX genes in different types of cancer. This analyses together with the result of immunohistochemistry indicated that CBX8 expression was significantly higher in lung adenocarcinoma (LUAD) tissues compared to adjacent nontumor tissues. Overexpression approaches demonstrated that CBX8 facilitated LUAD cell proliferation and migration in vitro. Consistently, CBX8 knockdown reduced LUAD cell proliferation and migration in both cell culture and mouse models. RNA sequencing combined with real-time RT-PCR assays revealed CDKN2C and SCEL as target genes of CBX8. Furthermore, chromatin immunoprecipitation assays indicated that CBX8 directly bound to the promoters of CDKN2C and SCEL to establish H2AK119ub. CBX8 depletion reduced the enrichment of H2AK119ub on CDKN2C and SCEL promoters. Moreover, depletion of CDKN2C and SCEL restored the repressed growth and invasion ability of LUAD cells caused by CBX8 knockdown. These findings demonstrate that CBX8 promotes LUAD growth and metastasis through the transcriptional repression of CDKN2C and SCEL. Our study uncovers the oncogenic role of CBX8 in LUAD progression and provides a new target for the diagnosis and therapy of LUAD.
Collapse
Affiliation(s)
- Hao Chen
- Haihe Laboratory of Cell Ecosystem, College of Life Sciences, Nankai University, Tianjin, China
- Department of Biochemistry and Molecular Biology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Yijie Su
- Department of Biochemistry and Molecular Biology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Lihong Yang
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, Tianjin, China
| | - Lishan Xi
- Department of Biochemistry and Molecular Biology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Xuanyuan Li
- Department of Biochemistry and Molecular Biology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Bei Lan
- Department of Biochemistry and Molecular Biology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| | - Min Liu
- Haihe Laboratory of Cell Ecosystem, College of Life Sciences, Nankai University, Tianjin, China
| | - Chenghao Xuan
- Department of Biochemistry and Molecular Biology, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, Tianjin Medical University, Tianjin, China
| |
Collapse
|
5
|
Ng L, Li HS, Man ATK, Chow AKM, Foo DCC, Lo OSH, Pang RWC, Law WL. High Expression of a Cancer Stemness-Related Gene, Chromobox 8 ( CBX8), in Normal Tissue Adjacent to the Tumor (NAT) Is Associated with Poor Prognosis of Colorectal Cancer Patients. Cells 2022; 11:cells11111852. [PMID: 35681547 PMCID: PMC9180723 DOI: 10.3390/cells11111852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 05/27/2022] [Accepted: 06/02/2022] [Indexed: 02/05/2023] Open
Abstract
Background: Several studies have demonstrated that the molecular profile of normal tissue adjacent to the tumor (NAT) is prognostic for recurrence in patients with different cancers. This study investigated the clinical significance of CBX8 gene expression, a cancer stemness-related gene, in tumor and NAT tissue of colorectal cancer (CRC) patients. Methods: The gene level of CBX8 in paired CRC and NAT specimens from 95 patients was determined by quantitative PCR. CBX8 protein level in CRC and NAT specimens from 66 patients was determined by immunohistochemistry. CBX8 gene and protein levels were correlated with the patients’ clinicopathological parameters and circulatory immune cell profiles. The association between CBX8 and pluripotency-associated genes was analyzed using the TCGA database. Results: NAT CBX8 gene level positively correlated with TNM stage, tumor invasion, lymph node metastasis and distant metastasis, indicating its association with tumor progression and metastasis. There was no correlation between NAT CBX8 protein level and clinicopathological parameters. Moreover, a high level of CBX8 gene and protein in NAT both correlated with poor DFS and OS. There was an inverse correlation between CBX8 gene level and post-operative platelet counts and platelet to lymphocyte level, suggesting its association with systematic inflammation. Finally, TCGA analysis showed that CBX8 level was correlated with a couple of pluripotency-associated genes, supporting its association with cancer stemness. Conclusions: High NAT CBX8 is a poor prognostic factor for tumor progression and survival in CRC patients.
Collapse
Affiliation(s)
- Lui Ng
- Correspondence: (L.N.); (W.-L.L.)
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Choi BH, Colon TM, Lee E, Kou Z, Dai W. CBX8 interacts with chromatin PTEN and is involved in regulating mitotic progression. Cell Prolif 2021; 54:e13110. [PMID: 34592789 PMCID: PMC8560621 DOI: 10.1111/cpr.13110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/14/2021] [Accepted: 07/27/2021] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVES Besides its role in regulating phosphatidylinositol-3 kinase (PI3K) signalling in the cytosol, PTEN also has a nuclear function. In this study, we attempted to understand the mechanism of chromatin PTEN in suppressing chromosomal instability during cell division. MATERIALS AND METHODS Immunocoprecipitation, ectopic expression, and deletional analyses were used to identify the physical interaction between Chromobox Homolog protein 8 (CBX8) and PTEN, as well as the functional domain(s) of PTEN mediating the interaction. Cell synchronization followed by immunoblotting was employed to study cell cycle regulation of CBX8 and the functional interaction between chromatin PTEN and CBX8. Small interfering RNAs (siRNAs) were used to study the role of PTEN and CBX8 in modulating histone epigenetic markers during the cell cycle. RESULTS Polycomb group (PcG) proteins including CBXs function to repress gene expression in a wide range of organisms including mammals. We recently showed that PTEN interacted with CBX8, a component of Polycomb Repressing Complex 1 (PRC1), and that CBX8 co-localized with PTEN in the nucleus. CBX8 levels were high, coinciding with its phosphorylation in mitosis. Phosphorylation of CBX8 was associated with monoubiquitinated PTEN and phosphorylated-BubR1 on chromatin. Moreover, CBX8 played an important role in cell proliferation and mitotic progression. Significantly, downregulation of either PTEN or CBX8 induced H3K27Me3 epigenetic marker in mitotic cells. CONCLUSION CBX8 is a new component that physically interacts with chromatin PTEN, playing an important role in regulating mitotic progression.
Collapse
Affiliation(s)
- Byeong Hyeok Choi
- Department of Environmental MedicineNew York University Grossman School of MedicineNew YorkNYUSA
| | - Tania Marlyn Colon
- Department of Environmental MedicineNew York University Grossman School of MedicineNew YorkNYUSA
| | - Eunji Lee
- Department of Environmental MedicineNew York University Grossman School of MedicineNew YorkNYUSA
| | - Ziyue Kou
- Department of Environmental MedicineNew York University Grossman School of MedicineNew YorkNYUSA
| | - Wei Dai
- Department of Environmental MedicineNew York University Grossman School of MedicineNew YorkNYUSA
- Department of Biochemistry and Molecular PharmacologyNew York University Langone Medical CenterNew YorkNYUSA
| |
Collapse
|
7
|
Milosevich N, Wilson CR, Brown TM, Alpsoy A, Wang S, Connelly KE, Sinclair KAD, Ponio FR, Hof R, Dykhuizen EC, Hof F. Polycomb Paralog Chromodomain Inhibitors Active against Both CBX6 and CBX8*. ChemMedChem 2021; 16:3027-3034. [PMID: 34174168 PMCID: PMC8497432 DOI: 10.1002/cmdc.202100262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/20/2021] [Indexed: 02/06/2023]
Abstract
Methyllysine reader proteins bind to methylated lysine residues and alter gene transcription by changing either the compaction state of chromatin or by the recruitment of other multiprotein complexes. The polycomb paralog family of methyllysine readers bind to trimethylated lysine on the tail of histone 3 (H3) via a highly conserved aromatic cage located in their chromodomains. Each of the polycomb paralogs are implicated in several disease states. CBX6 and CBX8 are members of the polycomb paralog family with two structurally similar chromodomains. By exploring the structure-activity relationships of a previously reported CBX6 inhibitor we have discovered more potent and cell permeable analogs. Our current report includes potent, dual-selective inhibitors of CBX6 and CBX8. We have shown that the -2 position in our scaffold is an important residue for selectivity amongst the polycomb paralogs. Preliminary cell-based studies show that the new inhibitors impact cell proliferation in a rhabdoid tumor cell line.
Collapse
Affiliation(s)
- Natalia Milosevich
- Department of Chemistry, University of Victoria, Victoria, BC, V8W 3V6, Canada
| | - Chelsea R. Wilson
- Department of Chemistry, University of Victoria, Victoria, BC, V8W 3V6, Canada
| | - Tyler M. Brown
- Department of Chemistry, University of Victoria, Victoria, BC, V8W 3V6, Canada
| | - Aktan Alpsoy
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 575 Stadium Mall Drive, West Lafayette, Indiana 47906, United States
| | - Sijie Wang
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 575 Stadium Mall Drive, West Lafayette, Indiana 47906, United States
| | - Katelyn E. Connelly
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 575 Stadium Mall Drive, West Lafayette, Indiana 47906, United States
| | | | - Felino R. Ponio
- Department of Chemistry, University of Victoria, Victoria, BC, V8W 3V6, Canada
| | - Rebecca Hof
- Department of Chemistry, University of Victoria, Victoria, BC, V8W 3V6, Canada
| | - Emily C. Dykhuizen
- Department of Medicinal Chemistry and Molecular Pharmacology, College of Pharmacy, Purdue University and Purdue University Center for Cancer Research, 575 Stadium Mall Drive, West Lafayette, Indiana 47906, United States
| | - Fraser Hof
- Department of Chemistry, University of Victoria, Victoria, BC, V8W 3V6, Canada
| |
Collapse
|
8
|
Shi D, Ao L, Yu H, Xia Y, Li J, Zhong W, Xia H. Chromobox Homolog 8 ( CBX8) in Human Tumor Carcinogenesis and Prognosis: A Pancancer Analysis Using Multiple Databases. Front Genet 2021; 12:745277. [PMID: 34567093 PMCID: PMC8458824 DOI: 10.3389/fgene.2021.745277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 08/12/2021] [Indexed: 12/12/2022] Open
Abstract
Some emerging studies have suggested that chromobox homolog 8 (CBX8) may play a critical role in carcinogenesis and prognosis in human cancer. Based on The Cancer Genome Atlas (TCGA)'s available data and the Gene Expression Omnibus (GEO) database, we conducted a systematic analysis of the carcinogenic effects of the CBX8 gene. We used TIMER2, GEPIA2, UALCAN, cBioPortal, Kaplan-Meier plotter, OncoLnc, STRING, HPA, and Oncomine data analysis websites and R data analysis software to analyze available data. The results show that the level of expression of CBX8 was significantly different among 27 different types of tumors and adjacent normal tissues. Moreover, we found that CBX8 expression had a close relationship with prognosis in some kinds of cancers. The phosphorylation level of some protein sites (such as S256) was significantly increased in tumors. CD8 + T-cell, B-cell and cancer-associated fibroblast infiltration levels were associated with CBX8 expression. The results of enrichment analysis indicated that the main biological activities of CBX8 are connected to gene transcription and repair of DNA damage. In conclusion, the level of expression of CBX8 was closely related to carcinogenesis and prognosis of some kinds of tumors, which needs further experimental verification.
Collapse
Affiliation(s)
- Dongjie Shi
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Lei Ao
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hua Yu
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yongzhi Xia
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Juan Li
- Clinical Skill Training Center, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Wenjie Zhong
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Haijian Xia
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| |
Collapse
|
9
|
Chen Y, Xu R, Ruze R, Yang J, Wang H, Song J, You L, Wang C, Zhao Y. Construction of a prognostic model with histone modification-related genes and identification of potential drugs in pancreatic cancer. Cancer Cell Int 2021; 21:291. [PMID: 34090418 PMCID: PMC8178883 DOI: 10.1186/s12935-021-01928-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 04/07/2021] [Indexed: 12/24/2022] Open
Abstract
Background Pancreatic cancer (PC) is a highly fatal and aggressive disease with its incidence and mortality quite discouraging. An effective prediction model is urgently needed for the accurate assessment of patients’ prognosis to assist clinical decision-making. Methods Gene expression data and clinicopathological data of the samples were acquired from The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Gene Expression Omnibus (GEO) databases. Differential expressed genes (DEGs) analysis, univariate Cox regression analysis, least absolute shrinkage and selection operator (LASSO) regression analysis, random forest screening and multivariate Cox regression analysis were applied to construct the risk signature. The effectiveness and independence of the model were validated by time-dependent receiver operating characteristic (ROC) curve, Kaplan–Meier (KM) survival analysis and survival point graph in training set, test set, TCGA entire set and GSE57495 set. The validity of the core gene was verified by immunohistochemistry and our own independent cohort. Meanwhile, functional enrichment analysis of DEGs between the high and low risk groups revealed the potential biological pathways. Finally, CMap database and drug sensitivity assay were utilized to identify potential small molecular drugs as the risk model-related treatments for PC patients. Results Four histone modification-related genes were identified to establish the risk signature, including CBX8, CENPT, DPY30 and PADI1. The predictive performance of risk signature was validated in training set, test set, TCGA entire set and GSE57495 set, with the areas under ROC curve (AUCs) for 3-year survival were 0.773, 0.729, 0.775 and 0.770 respectively. Furthermore, KM survival analysis, univariate and multivariate Cox regression analysis proved it as an independent prognostic factor. Mechanically, functional enrichment analysis showed that the poor prognosis of high-risk population was related to the metabolic disorders caused by inadequate insulin secretion, which was fueled by neuroendocrine aberration. Lastly, a cluster of small molecule drugs were identified with significant potentiality in treating PC patients. Conclusions Based on a histone modification-related gene signature, our model can serve as a reliable prognosis assessment tool and help to optimize the treatment for PC patients. Meanwhile, a cluster of small molecule drugs were also identified with significant potentiality in treating PC patients. Supplementary Information The online version contains supplementary material available at 10.1186/s12935-021-01928-6.
Collapse
Affiliation(s)
- Yuan Chen
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Ruiyuan Xu
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Rexiati Ruze
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Jinshou Yang
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Huanyu Wang
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Jianlu Song
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Lei You
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China
| | - Chengcheng Wang
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China.
| | - Yupei Zhao
- Department of General Surgery, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, 100023, People's Republic of China.
| |
Collapse
|
10
|
van Wijnen AJ, Bagheri L, Badreldin AA, Larson AN, Dudakovic A, Thaler R, Paradise CR, Wu Z. Biological functions of chromobox (CBX) proteins in stem cell self-renewal, lineage-commitment, cancer and development. Bone 2021; 143:115659. [PMID: 32979540 DOI: 10.1016/j.bone.2020.115659] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 09/02/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Epigenetic regulatory proteins support mammalian development, cancer, aging and tissue repair by controlling many cellular processes including stem cell self-renewal, lineage-commitment and senescence in both skeletal and non-skeletal tissues. We review here our knowledge of epigenetic regulatory protein complexes that support the formation of inaccessible heterochromatin and suppress expression of cell and tissue-type specific biomarkers during development. Maintenance and formation of heterochromatin critically depends on epigenetic regulators that recognize histone 3 lysine trimethylation at residues K9 and K27 (respectively, H3K9me3 and H3K27me3), which represent transcriptionally suppressive epigenetic marks. Three chromobox proteins (i.e., CBX1, CBX3 or CBX5) associated with the heterochromatin protein 1 (HP1) complex are methyl readers that interpret H3K9me3 marks which are mediated by H3K9 methyltransferases (i.e., SUV39H1 or SUV39H2). Other chromobox proteins (i.e., CBX2, CBX4, CBX6, CBX7 and CBX8) recognize H3K27me3, which is deposited by Polycomb Repressive Complex 2 (PRC2; a complex containing SUZ12, EED, RBAP46/48 and the methyl transferases EZH1 or EZH2). This second set of CBX proteins resides in PRC1, which has many subunits including other polycomb group factors (PCGF1, PCGF2, PCGF3, PCGF4, PCGF5, PCGF6), human polyhomeotic homologs (HPH1, HPH2, HPH3) and E3-ubiquitin ligases (RING1 or RING2). The latter enzymes catalyze the subsequent mono-ubiquitination of lysine 119 in H2A (H2AK119ub). We discuss biological, cellular and molecular functions of CBX proteins and their physiological and pathological activities in non-skeletal cells and tissues in anticipation of new discoveries on novel roles for CBX proteins in bone formation and skeletal development.
Collapse
Affiliation(s)
- Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America; Biochemistry & Molecular Biology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America; Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, United States of America.
| | - Leila Bagheri
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America.
| | - Amr A Badreldin
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America.
| | - A Noelle Larson
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America.
| | - Amel Dudakovic
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America; Biochemistry & Molecular Biology, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America.
| | - Roman Thaler
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America.
| | - Christopher R Paradise
- Center for Regenerative Medicine, Mayo Clinic, Rochester, MN, United States of America; Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, United States of America
| | - Zhong Wu
- Department of Orthopedic Surgery, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN, United States of America
| |
Collapse
|
11
|
Song X, Ning W, Niu J, Zhang G, Liu H, Zhou L. CBX8 acts as an independent RNA-binding protein to regulate the maturation of miR-378a-3p in colon cancer cells. Hum Cell 2021; 34:515-29. [PMID: 33417156 DOI: 10.1007/s13577-020-00477-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/22/2020] [Indexed: 10/22/2022]
Abstract
CBX8 is the core component of the PCG family protein PRC1 complex. It is overexpressed in many solid tumors and plays an important role in the prognosis and biological behaviors of tumors such as occurrence, development, invasion, and metastasis. However, exploration of the role and molecular mechanism of CBX8 in tumors is still in its infancy. Our study found that the down-regulation of CBX8 expression by RNA interference induced differential expression of several microRNAs in human colon cancer cells. The 5 most differentially expressed miRNA precursors (pre-miRNA) (hsa-miR-363-3p, hsa-miR-378a-3p, hsa-miR-371b-3p, hsa-miR-361-3p, and hsa-miR-576-3p) share a common motif sequence: ARAAAKUGCMC. We selected miR-378a-3p and further revealed that the negative regulation of miRNA expression by CBX8 mainly occurs in the processing of pre-miRNA to mature miRNA. CBX8 uses its own RNA-binding domain to interact with pre-miRNA, and is dependent on its own nuclear localization characteristics to limit nucleoplasmic transport of pre-miRNA. Changing the characteristic sequence of pre-miRNA or mutating the RNA-binding domain and nuclear localization signal of CBX8 can effectively weaken the regulation of miR-378a-3p expression by CBX8. However, our experimental results showed that miR-378a-3p inhibited the malignant expression of human colon cancer cells by targeting PDIA4, resulting in increased activity of caspases-3 and -7. In summary, our study suggests that CBX8 acts as an independent RNA-binding protein to regulate miRNA expression. Simultaneously, this study shows the correlation between the CBX8/miR-378a-3p/PDIA4 pathway and the malignant biological properties of colorectal cancer, suggesting this proposed pathway as a possible therapeutic target for human cancers.
Collapse
|
12
|
Jia Y, Wang Y, Zhang C, Chen MY. Upregulated CBX8 Promotes Cancer Metastasis via the WNK2/ MMP2 Pathway. Mol Ther Oncolytics 2020; 19:188-196. [PMID: 33251331 PMCID: PMC7666318 DOI: 10.1016/j.omto.2020.09.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 09/30/2020] [Indexed: 12/28/2022]
Abstract
Metastasis is associated with poor prognosis in cancer and is a multistep process that includes invasion and migration. Several epigenetic factors are involved in this process, including chromobox protein homolog 8 (CBX8). Here, we show that CBX8 is overexpressed in many cancers compared with normal tissues. Functional analyses indicated that CBX8 promoted invasion and migration in glioblastoma, breast cancer, and lung cancer in vitro and in vivo. WNK2 was identified as a target gene of CBX8, which interacted with the WNK2 promoter to suppress WNK2 expression and activity. WNK2 acted as an antioncogene, and decreased WNK2 levels resulted in high activity of matrix metalloprotease (MMP)-2 and RAC1, which play a central role in invasion and migration, respectively. There was a positive relationship between MMP2 and RAC1 activity in CBX8-modulated cell lines. In addition, WNK2 negatively regulated MMP2 and RAC1 activity. Collectively, the results indicated that CBX8 promoted invasion and migration by targeting WNK2, which resulted in increased RAC1 and MMP2 expression and activity. Therefore, CBX8 may be a novel therapeutic target to treat metastatic cancers.
Collapse
Affiliation(s)
- Yongsheng Jia
- Thyroid and Neck Department, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
- Division of Neurosurgery, City of Hope and Beckman Research Institute, Duarte, CA, USA
| | - Yujun Wang
- Division of Neurosurgery, City of Hope and Beckman Research Institute, Duarte, CA, USA
| | - Cuicui Zhang
- Department of Thoracic Oncology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
- Tianjin’s Clinical Research Center for Cancer, Tianjin, China
| | - Mike Yue Chen
- Division of Neurosurgery, City of Hope and Beckman Research Institute, Duarte, CA, USA
- Key Laboratory of Cancer Prevention and Therapy, Tianjin, China
- Corresponding author: Mike Yue Chen, Division of Neurosurgery, City of Hope and Beckman Research Institute, City of Hope, Duarte, CA 91010.
| |
Collapse
|
13
|
Badreldin AA, Bagheri L, Zhang B, Larson AN, van Wijnen AJ. Relative mRNA and protein stability of epigenetic regulators in musculoskeletal cell culture models. Gene 2020; 766:145032. [PMID: 32771387 DOI: 10.1016/j.gene.2020.145032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/04/2020] [Accepted: 08/04/2020] [Indexed: 11/19/2022]
Abstract
Control of gene expression by epigenetic regulators is fundamental to tissue development and homeostasis. Loss-of-function (LOF) studies using siRNAs for epigenetic regulators require that RNA interference rapidly reduces the cellular levels of the corresponding mRNAs and/or proteins. The most abundant chromatin structural proteins (i.e., the core histones H2A, H2B, H3 and H4) have relatively long half-lives and do not turn over rapidly, although their mRNAs are labile. The question arises whether epigenetic regulatory enzymes (e.g., Ezh2) or proteins that interact with histones via selective modifications (e.g., Cbx1 to Cbx8, Brd4) are stable or unstable. Therefore, we performed classical α-amanitin and cycloheximide inhibition assays that block, respectively, mRNA transcription and protein translation in mouse MC3T3 osteoblasts, ATDC5 chondrocytes and C2C12 myoblasts. We find that mRNA levels of Cbx proteins and Ezh2 were significantly depleted after 24 hrs, while their corresponding proteins remained relatively stable. As positive control, the half-life of the labile cyclin D1 protein was found to be less than 1 hr. Our study suggests that histone code readers and writers are relatively stable chromatin-related proteins, which is consistent with their long-term activities in maintaining chromatin organization and phenotype identity. These findings have conceptual ramifications for the interpretation of RNAi experiments that reduce the mRNA but not protein levels of epiregulatory proteins. We propose that siRNAs for at least some epigenetic regulatory proteins may exert their biological effects by blocking translation and new protein synthesis rather than by decreasing pre-existing protein pools.
Collapse
Affiliation(s)
- Amr A Badreldin
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
| | - Leila Bagheri
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
| | - Bangke Zhang
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA
| | - A Noelle Larson
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
| | - Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA.
| |
Collapse
|
14
|
Zhang Y, Kang M, Zhang B, Meng F, Song J, Kaneko H, Shimamoto F, Tang B. m 6A modification-mediated CBX8 induction regulates stemness and chemosensitivity of colon cancer via upregulation of LGR5. Mol Cancer 2019; 18:185. [PMID: 31849331 PMCID: PMC6918584 DOI: 10.1186/s12943-019-1116-x] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 12/03/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Colon cancer (CC) cells can exhibit stemness and expansion capabilities, which contribute to resistance to conventional chemotherapies. Aberrant expression of CBX8 has been identified in many types of cancer, but the cause of this aberrant CBX8 expression and whether CBX8 is associated with stemness properties in CC remain unknown. METHODS qRT-PCR and IHC were applied to examine CBX8 levels in normal and chemoresistant CC tissues. Cancer cell stemness and chemosensitivity were evaluated by spheroid formation, colony formation, Western blot and flow cytometry assays. RNA-seq combined with ChIP-seq was used to identify target genes, and ChIP, IP and dual luciferase reporter assays were applied to explore the underlying mechanisms. RESULTS CBX8 was significantly overexpressed in chemoresistant CC tissues. In addition, CBX8 could promote stemness and suppress chemosensitivity through LGR5. Mechanistic studies revealed that CBX8 activate the transcription of LGR5 in a noncanonical manner with assistance of Pol II. CBX8 recruited KMT2b to the LGR5 promoter, which maintained H3K4me3 status to promote LGR5 expression. Moreover, m6A methylation participated in the upregulation of CBX8 by maintaining CBX8 mRNA stability. CONCLUSIONS Upon m6A methylation-induced upregulation, CBX8 interacts with KMT2b and Pol II to promote LGR5 expression in a noncanonical manner, which contributes to increased cancer stemness and decreased chemosensitivity in CC. This study provides potential new therapeutic targets and valuable prognostic markers for CC.
Collapse
Affiliation(s)
- Yi Zhang
- Department of Health Sciences, Hiroshima Shudo University, 1-1-1, Ozuka-higashi, Asaminami-ku, Hiroshima, 731-3195, Japan
- Department of General Surgery, Affiliated hospital of Xuzhou Medical University, Xuzhou, 221000, China
| | - Min Kang
- Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, 06510, USA
| | - Bin Zhang
- Department of Oncology, The First Affiliated Hospital of Dalian Medical University, Dalian, 116011, China
| | - Fanchao Meng
- Department of General Surgery, Affiliated hospital of Xuzhou Medical University, Xuzhou, 221000, China
| | - Jun Song
- Department of General Surgery, Affiliated hospital of Xuzhou Medical University, Xuzhou, 221000, China
| | - Hiroshi Kaneko
- Department of Health Sciences, Hiroshima Shudo University, 1-1-1, Ozuka-higashi, Asaminami-ku, Hiroshima, 731-3195, Japan
| | - Fumio Shimamoto
- Department of Health Sciences, Hiroshima Shudo University, 1-1-1, Ozuka-higashi, Asaminami-ku, Hiroshima, 731-3195, Japan.
| | - Bo Tang
- Department of Health Sciences, Hiroshima Shudo University, 1-1-1, Ozuka-higashi, Asaminami-ku, Hiroshima, 731-3195, Japan.
| |
Collapse
|
15
|
Xiao L, Zhou Z, Li W, Peng J, Sun Q, Zhu H, Song Y, Hou JL, Sun J, Cao HC, Zhongyi D, Wu D, Liu L. Chromobox homolog 8 ( CBX8) Interacts with Y-Box binding protein 1 (YBX1) to promote cellular proliferation in hepatocellular carcinoma cells. Aging (Albany NY) 2019; 11:7123-7149. [PMID: 31495785 PMCID: PMC6756871 DOI: 10.18632/aging.102241] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Accepted: 08/22/2019] [Indexed: 12/24/2022]
Abstract
Polycomb group (PcG) proteins have recently been identified as critical regulators in tumor initiation and development. However, the function of CBX8 in human hepatocellular carcinoma (HCC) remains largely unknown. Our study was designed to explore the biological function and clinical implication of CBX8 in HCC. We investigated the interplay between CBX8 and cell cycle through Gene Set Enrichment Analysis and western blotting. Bioinformatics tools and co-immunoprecipitation were used to explore cell cycle regulation. Finally, we studied the expression and clinical significance of CBX8 in HCC through 3 independent datasets. CBX8 was upregulated in HCC and its expression correlated with cell cycle progression. CyclinD1 was downregulated by CBX8 knockdown but upregulated by CBX8 overexpression. YBX1 interacted with CBX8 and regulated the cell cycle. Moreover, targeting YBX1 with specific siRNA impaired CBX8-mediated regulation of CyclinD1. CBX8 overexpression boosted HCC cell growth, while CBX8 knockdown suppressed cell proliferation. Further, YBX1 interacted with CBX8. YBX1 knockdown compromised the proliferation of CBX8 overexpressing cells. CBX8 promotes HCC cell proliferation through YBX1 mediated cell cycle progression and is related to poor HCC prognoses. Therefore, CBX8 may serve as a potential target for the diagnosis and treatment of HCC.
Collapse
Affiliation(s)
- Lushan Xiao
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Zixiao Zhou
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Wenwen Li
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jie Peng
- Department of Oncology, The Second Affiliated Hospital, Guizhou Medical University, Kaili, P.R. China
| | - Qingcan Sun
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Hongbo Zhu
- Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Medical Oncology, The First Affiliated Hospital of University of South China, Hengyang, Hunan 421001, P.R. China
| | - Yang Song
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jin-Lin Hou
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Jingyuan Sun
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Radiation Oncology, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Hui-Chuan Cao
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Radiation Oncology, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Dong Zhongyi
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Radiation Oncology, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Dehua Wu
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Radiation Oncology, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Li Liu
- State Key Laboratory of Organ Failure Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Nan Fang Hospital, Southern Medical University, Guangzhou 510515, China.,Department of Infectious Diseases, Nan fang Hospital, Southern Medical University, Guangzhou 510515, China
| |
Collapse
|
16
|
Zhan X, Yang J, Mao Z, Yu W. PIM1-catalyzed CBX8 phosphorylation promotes the oncogene-induced senescence of human diploid fibroblast. Biochem Biophys Res Commun 2019; 501:779-785. [PMID: 29763603 DOI: 10.1016/j.bbrc.2018.05.070] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 05/11/2018] [Indexed: 11/24/2022]
Abstract
The proto-oncogene PIM1 encodes Ser/Thr kinase and regulates cell growth, differentiation and apoptosis. However, more and more studies including ours have found that PIM1 can induce senescence in normal human diploid fibroblasts and behave as a tumor suppressor. But the relevant molecular mechanism of this process is not yet clear. It has been reported that Chromobox homolog 8 (CBX8) binds directly to INK4A as a transcriptional repressor, thereby suppressing stress-induced senescence. Here we report that PIM1 can phosphorylate CBX8 to promote its degradation, thereby up-regulating p16, during PIM1-induced cell senescence. Overexpression of CBX8 can inhibit PIM1-induced cell senescence. These data suggest that to promote CBX8 degradation may be an important molecular mechanism of PIM1-induced cell senescence.
Collapse
Affiliation(s)
- Xiangwen Zhan
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, People's Republic of China
| | - Jianming Yang
- Department of Immunology, School of Basic Medical Science, Tianjing Medical University, People's Republic of China
| | - Zebin Mao
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, People's Republic of China
| | - Wenhua Yu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, People's Republic of China.
| |
Collapse
|
17
|
Xu Y, Yao Y, Leng K, Ji D, Qu L, Liu Y, Cui Y. Increased Expression of Circular RNA circ_0005230 Indicates Dismal Prognosis in Breast Cancer and Regulates Cell Proliferation and Invasion via miR-618/ CBX8 Signal Pathway. Cell Physiol Biochem 2018; 51:1710-1722. [PMID: 30504704 DOI: 10.1159/000495675] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/22/2018] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND/AIMS Circular RNAs (circRNAs) are a class of non-coding RNAs. They have been proved to be critically involved in tumorigenesis and progression of malignancies through competing endogenous RNA (ceRNA) mechanism. Nevertheless, the exploration between circRNAs and pathogenesis of breast cancer (BC) is limited. Previously, circ_0005230 was identified upregulated in BC tissues screened by circRNA microarray. In the present study, we aimed to investigate the expression pattern, functional role, and mechanism of circ_0005230 in BC. METHODS qRT-PCR was conducted to elucidate the expression levels of circ_0005230 in BC tissues and cells. Additionally, the clinical severity and prognostic value were investigated. CCK-8, colony-forming, flow cytometric assays were performed. Animal study was conducted to validate the in vitro data. What's more, Transwell assays were induced to detect the cell metastatic properties of circ_0005230 exerts in BC cells. Luciferase reporter assay was used to measure the mechanism of circ_0005230. RESULTS circ_0005230 was overexpressed in BC tissue specimens and cell lines. The overexpression of circ_0005230 was related to adverse phenotypes in the patients with BC. In addition, circ_0005230 could be regarded as a prognostic predictor in BC patients. In vitro and in vivo data demonstrated the cell growth promoting role of circ_0005230. Moreover, circ_0005230 could also promote cell migratory and invasive capacities. For the mechanism investigation, circ_0005230 was proved to be a sponge of miR-618, and expression of miR-618 could regulate CBX8 expression via targeting the 3'UTR of CBX8. Rescue assays also illustrated an oncogenic function of circ_0005230 in BC via acting as a miR-618 sponge to promote CBX8 expression. CONCLUSION circ_0005230/miR-618/CBX8 axis might play a key role in BC tumorigenesis and development.
Collapse
Affiliation(s)
- Yi Xu
- Department of Hepatopancreatobiliary Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin, China.,The Key Laboratory of Myocardial Ischemia, Harbin Medical University, Ministry of Education, Harbin, China
| | - Yue Yao
- Department of Endocrinology and Metabolism, Second Affiliated Hospital of Harbin Medical University, Harbin, China.,The Key Laboratory of Myocardial Ischemia, Harbin Medical University, Ministry of Education, Harbin, China
| | - Kaiming Leng
- Department of Hepatopancreatobiliary Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin, China.,The Key Laboratory of Myocardial Ischemia, Harbin Medical University, Ministry of Education, Harbin, China
| | - Daolin Ji
- Department of Hepatopancreatobiliary Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin, China.,The Key Laboratory of Myocardial Ischemia, Harbin Medical University, Ministry of Education, Harbin, China
| | - Lijun Qu
- Department of Ophthalmology, Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yueping Liu
- Department of Hepatopancreatobiliary Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin, China
| | - Yunfu Cui
- Department of Hepatopancreatobiliary Surgery, Second Affiliated Hospital of Harbin Medical University, Harbin,
| |
Collapse
|
18
|
Liu J, Wang D, Long Z, Liu J, Li W. CircRNA8924 Promotes Cervical Cancer Cell Proliferation, Migration and Invasion by Competitively Binding to MiR-518d-5p /519-5p Family and Modulating the Expression of CBX8. Cell Physiol Biochem 2018; 48:173-184. [PMID: 30007986 DOI: 10.1159/000491716] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 04/26/2018] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Circular RNAs (circRNAs) play a significant role in the development and progression of various human cancers. However, the expression and function of circRNAs in cervical cancer (CC) have rarely been explored. The aim of this study was to investigate the biological function of circRNA8924 in CC and elucidate the possible molecular mechanism involved. METHODS Quantitative polymerase chain reaction was used to determine mRNA expression of circRNA8924, miR-518d-5p/519-5p and CBX8 in CC tissues and cells. CBX8 protein expression was measured by Western blotting. The CCK-8 assay was used to evaluate cell proliferation, and the transwell assay to determine cell migration and invasion. The luciferase reporter assay was used to determine the direct regulation of miR-518d-5p/519-5p and circRNA8924 or CBX8 Results: The study demonstrated that the expression level of circRNA8924 in CC was significantly higher than that in the adjacent normal tissues (P < 0.001), and that it was also associated with tumor size, FIGO staging and myometrial invasion. The knockdown of circRNA8924 significantly inhibited the proliferation, migration and invasion of CC cells SiHa and HeLa. The expression level of miR-518d-5p/519-5p was negatively correlated with circRNA8924, and circRNA8924 regulated CBX8 by competitively binding to miR-518d-5p/519-5p. CONCLUSIONS CircRNA8924 is highly expressed in CC tissue and can be considered a competitive endogenous RNA of the miR-518d-5p/519-5p family to promote the malignant biological behavior of CC cells. It is suggested that it may serve as a new biomarker for CC diagnosis and disease progression and provide potential targets for targeted therapy.
Collapse
|
19
|
Yuan G, Chen X, Lu J, Feng Z, Chen S, Chen R, Wei W, Zhou F, Xie D. Chromobox homolog 8 is a predictor of muscle invasive bladder cancer and promotes cell proliferation by repressing the p53 pathway. Cancer Sci 2017; 108:2166-2175. [PMID: 28837252 PMCID: PMC5665758 DOI: 10.1111/cas.13383] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/08/2017] [Accepted: 08/16/2017] [Indexed: 12/16/2022] Open
Abstract
Chromobox homolog 8 (CBX8), also known as human polycomb 8, is a repressor that maintains the transcriptionally repressive state in various cellular genes, and has been reported to promote tumorigenesis. In the present study, we examined CBX8 expression in eight pairs of muscle invasive bladder cancer tissues and adjacent non-tumor tissues, and found that CBX8 was frequently upregulated in muscle invasive bladder cancer tissues when compared to adjacent non-tumor tissues. Analysis showed that high expression of CBX8 in 152 muscle invasive bladder cancer specimens was associated with progression of the T, N, and M stages (P = 0.004, 0.005, <0.001, respectively). Furthermore, Kaplan-Meier survival analysis and log-rank test showed that muscle invasive bladder cancer patients with high CBX8 expression had a poor rate of overall survival (P < 0.001) and 5-year recurrence-free survival (P < 0.001) compared to patients with low CBX8 expression. High CBX8 expression predicted poor overall survival and 5-year recurrence-free survival in T and N stages of muscle invasive bladder cancer patients. Moreover, knockdown of CBX8 inhibited cell proliferation of urothelial carcinoma of the bladder both in vitro and in vivo. In addition, CBX8 depletion resulted in cell cycle delay of urothelial carcinoma cells of the bladder at the G2/M phase by the p53 pathway. The data suggest that high expression of CBX8 plays a critical oncogenic role in aggressiveness of urothelial carcinoma cells of the bladder through promoting cancer cell proliferation by repressing the p53 pathway, and CBX8 could be used as a novel predictor for muscle invasive bladder cancer patients.
Collapse
Affiliation(s)
- Gang‐jun Yuan
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina,Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
| | - Xin Chen
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina,Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
| | - Jun Lu
- Department of UrologyThe First Affiliated Hospital of Sun Yat‐sen UniversityGuangzhouChina
| | - Zi‐hao Feng
- Department of UrologyThe First Affiliated Hospital of Sun Yat‐sen UniversityGuangzhouChina
| | - Si‐liang Chen
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
| | - Ri‐xin Chen
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| | - Wen‐su Wei
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
| | - Fang‐jian Zhou
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina,Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
| | - Dan Xie
- State Key Laboratory of Oncology in South ChinaCollaborative Innovation Center for Cancer MedicineSun Yat‐sen University Cancer CenterGuangzhouChina
| |
Collapse
|
20
|
Wang G, Tang J, Zhan W, Zhang R, Zhang M, Liao D, Wang X, Wu Y, Kang T. CBX8 Suppresses Tumor Metastasis via Repressing Snail in Esophageal Squamous Cell Carcinoma. Theranostics 2017; 7:3478-3488. [PMID: 28912889 PMCID: PMC5596437 DOI: 10.7150/thno.20717] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 06/15/2017] [Indexed: 12/31/2022] Open
Abstract
The poor clinical outcome and prognosis of esophageal squamous cell carcinoma (ESCC) is mainly attributed to its highly invasive and metastatic nature, making it urgent to further elicit the molecular mechanisms of the metastasis of ESCC. The function of each polycomb chromobox (CBX) protein in cancer is cell-type-dependent. Although CBX8 has been reported to promote the esophageal squamous cell carcinoma (ESCC) tumorigenesis, its role in ESCC metastasis has not been explored yet. In this study, we report that the inhibition of cell migration, invasion, and metastasis in ESCC requires CBX8-mediated repression of Snail, a key transcription factor that induces epithelial-to-mesenchymal transition (EMT), and that CBX8 inversely correlated with Snail in the ESCC tissues. Moreover, this novel function of CBX8 is dependent on its binding with the Snail promoter, which in turn suppresses the transcription of Snail. Collectively, CBX8 may play paradoxical roles in ESCC, inhibiting metastasis while promoting cell proliferation.
Collapse
|
21
|
Oza J, Ganguly B, Kulkarni A, Ginjala V, Yao M, Ganesan S. A Novel Role of Chromodomain Protein CBX8 in DNA Damage Response. J Biol Chem 2016; 291:22881-22893. [PMID: 27555324 DOI: 10.1074/jbc.m116.725879] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Indexed: 12/18/2022] Open
Abstract
Induction of DNA damage induces a dynamic repair process involving DNA repair factors and epigenetic regulators. Chromatin alterations must occur for DNA repair factors to gain access to DNA lesions and restore original chromatin configuration to preserve the gene expression profile. We characterize the novel role of CBX8, a chromodomain-containing protein with established roles in epigenetic regulation in DNA damage response. CBX8 protein rapidly accumulates at the sites of DNA damage within 30 s and progresses to accumulate until 4 min before gradually dispersing back to its predamage distribution by 15 min. CBX8 recruitment to the sites of DNA damage is dependent upon PARP1 activation and not dependent on ATM activation. CBX8 biochemically interacts with TRIM33, and its recruitment to DNA damage is also dependent on the presence of TRIM33. Knockdown of CBX8 using siRNA significantly reduces the efficiency of both homologous and the other non-homologous recombination, as well as increases sensitivity of cells to ionizing radiation. These findings demonstrate that CBX8 functions in the PARP-dependent DNA damage response partly through interaction with TRIM33 and is required for efficient DNA repair.
Collapse
Affiliation(s)
- Jay Oza
- From the MD-PhD Program, Rutgers-Robert Wood Johnson Medical School, New Brunswick, New Jersey 08903.,the Department of Cellular and Molecular Pharmacology, Rutgers-Graduate School of Biomedical Sciences, Piscataway, New Jersey 08854.,the Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and.,the Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire 03766
| | - Bratati Ganguly
- the Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| | - Atul Kulkarni
- the Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| | - Vasudeva Ginjala
- the Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| | - Ming Yao
- the Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| | - Shridar Ganesan
- the Department of Cellular and Molecular Pharmacology, Rutgers-Graduate School of Biomedical Sciences, Piscataway, New Jersey 08854, .,the Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey 08903, and
| |
Collapse
|
22
|
Lee SH, Um SJ, Kim EJ. CBX8 antagonizes the effect of Sirtinol on premature senescence through the AKT-RB-E2F1 pathway in K562 leukemia cells. Biochem Biophys Res Commun 2015; 469:884-90. [PMID: 26718407 DOI: 10.1016/j.bbrc.2015.12.070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 01/08/2023]
Abstract
Although tyrosine kinase inhibitor (TKI) therapies are highly effective in the treatment of chronic myeloid leukemia (CML), frequent recurrence limits their usage and demands new approaches for CML therapy. Stress-induced premature senescence (SIPS) is considered a potential anticancer treatment, but the underlying mechanism remains elusive. Here, we report that Sirtinol, a known SIRT1 inhibitor, induces premature senescence and growth arrest in K562 CML cells. Chromobox homolog 8 (CBX8) suppresses the Sirtinol-induced premature senescence, which is reversed by CBX8 knockdown. Upon Sirtinol treatment, the phosphorylation of AKT1, p27KIP1 and RB is severely downregulated. However, CBX8 overexpression enhances phosphorylation and, thereby, promotes the transcriptional activity of E2F1, both of which are impaired upon CBX depletion. These data suggest that CBX8 modulates SIPS through the RB-E2F1 pathway in CML cells and provide important insight into its application in CML treatment.
Collapse
Affiliation(s)
- Sang Hyup Lee
- Department of Molecular Biology, Dankook University, Yongin-si, Gyeonggi-do, 448-701, South Korea
| | - Soo-Jong Um
- Department of Bioscience and Biotechnology/Institute of Bioscience, BK21 Graduate Program, Sejong University, Seoul, 143-747, South Korea
| | - Eun-Joo Kim
- Department of Molecular Biology, Dankook University, Yongin-si, Gyeonggi-do, 448-701, South Korea.
| |
Collapse
|
23
|
Xiao W, Ou C, Qin J, Xing F, Sun Y, Li Z, Qiu J. CBX8, a novel DNA repair protein, promotes tumorigenesis in human esophageal carcinoma. Int J Clin Exp Pathol 2014; 7:4817-4826. [PMID: 25197352 PMCID: PMC4152042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 08/02/2014] [Indexed: 06/03/2023]
Abstract
DNA damage response and repair are carried out by certain proteins following damage by environmental clastogens, such as ionizing radiation and reactive oxygen species. It has been reported that many carcinomas that are characterized by resistance to chemotherapy and poor outcomes show dysfunction of these proteins. Chromobox homologue 8 (CBX8), a member of the polycomb group of proteins, has been identified as a factor that protects tumor cells from the detrimental effects of ionizing radiation (IR) or hydrogen peroxide (H2O2). In this study, we found that CBX8 was up-regulated in esophageal carcinoma tissues compared with adjacent non-cancerous tissues (P<0.01) and correlated with TNM stage in esophageal squamous cell carcinoma patients. Depletion of CBX8 decreased cell proliferation both in vitro and in vivo and increased the phosphorylation levels of p21, Wee1, and CHK1, which result in cyclin-dependent kinase inhibition and cell-cycle delay. CBX8 depletion also led to accumulation of spontaneous DNA damage and raised the sensitivity of tumor cells to IR or H2O2. We also found that the total level of CBX8 in the cells was increased after treating tumor cells with clastogens. In addition, our data showed that decreased CBX8 expression was accompanied by the reduction of EZH2 and EED, which have been reported to participate in DNA damage repair. Collectively, CBX8 might emerge as an oncogene for promoting the proliferation of tumor cells and raising the resistance of neoplasms to chemotherapy.
Collapse
Affiliation(s)
- Weifan Xiao
- Department of Gynaecology and Obstetrics, Shanghai Tenth People’s Hospital of Tongji UniversityShanghai 200072, China
| | - Chao Ou
- Department of Clinical Laboratory, The Affiliated Tumor Hospital of Guangxi Medical UniversityNanning 530021, Guangxi Province, China
| | - Jinlong Qin
- Department of Gynaecology and Obstetrics, Shanghai Tenth People’s Hospital of Tongji UniversityShanghai 200072, China
| | - Feng Xing
- Department of Gynaecology and Obstetrics, Shanghai Tenth People’s Hospital of Tongji UniversityShanghai 200072, China
| | - Yi Sun
- Department of Gynaecology and Obstetrics, Shanghai Tenth People’s Hospital of Tongji UniversityShanghai 200072, China
| | - Zhi Li
- Department of Clinical Laboratory Medicine, Shanghai Yangpu District Central HospitalShanghai 200433, China
| | - Jin Qiu
- Department of Gynaecology and Obstetrics, Shanghai Tenth People’s Hospital of Tongji UniversityShanghai 200072, China
| |
Collapse
|