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Mehta H, Ambele MA, Mokgautsi N, Moela P. Probing the Effects of Retinoblastoma Binding Protein 6 (RBBP6) Knockdown on the Sensitivity of Cisplatin in Cervical Cancer Cells. Cells 2024; 13:700. [PMID: 38667315 PMCID: PMC11049397 DOI: 10.3390/cells13080700] [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: 01/03/2024] [Revised: 04/05/2024] [Accepted: 04/13/2024] [Indexed: 04/28/2024] Open
Abstract
Cervical cancer is a major cause of death in women despite the advancement of current treatment modalities. The conventional therapeutic agent, cisplatin (CCDP), is the standard treatment for CC; however, resistance often develops due to the cancer's heterogeneity. Therefore, a detailed elucidation of the specific molecular mechanisms driving CC is crucial for the development of targeted therapeutic strategies. Retinoblastoma binding protein 6 (RBBP6) is a potential biomarker associated with cell proliferation and is upregulated in cervical cancer sites, exhibiting apoptosis and dysregulated p53 expression. Furthermore, RBBP6 has been demonstrated to sensitize cancer cells to radiation and certain chemotherapeutic agents by regulating the Bcl-2 gene, thus suggesting a crosstalk among RBBP6/p53/BCL-2 oncogenic signatures. The present study, therefore, investigated the relationship between cisplatin and RBBP6 expression in CC cells. Herein, we first explored bioinformatics simulations and identified that the RBBP6/p53/BCL-2 signaling pathway is overexpressed and correlated with CC. For further analysis, we explored the Genomics of Drug Sensitivity in Cancer (GDSC) and found that most of the CC cell lines are sensitive to CCDP. To validate these findings, RBBP6 was silenced in HeLa and Vero cells using RNAi technology, followed by measurement of wild-type p53 and Bcl-2 at the mRNA level using qPCR. Cells co-treated with cisplatin and siRBBP6 were subsequently analyzed for apoptosis induction and real-time growth monitoring using flow cytometry and the xCELLigence system, respectively. Cancer cells in the co-treatment group showed a reduction in apoptosis compared to the cisplatin-treated group. Moreover, the real-time growth monitoring revealed a reduced growth rate in RBBP6 knockdown cells treated with cisplatin. Although wild-type p53 remained unchanged in the co-treatment group of cancer cells, Bcl-2 was completely repressed, suggesting that RBBP6 is necessary for sensitizing cervical cancer cells to cisplatin treatment by downregulating Bcl-2. The Vero cell population, which served as a non-cancerous control cell line in this study, remained viable following treatment with both siRBBP6 and cisplatin. Findings from this study suggest that RBBP6 expression promotes cisplatin sensitivity in HeLa cells through Bcl-2 downregulation. Knockdown of RBBP6 limits apoptosis induction and delays cell growth inhibition in response to cisplatin. The knowledge obtained here has the potential to help improve cisplatin efficacy through personalized administration based on the expression profile of RBBP6 among individual patients.
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Affiliation(s)
- Harshini Mehta
- Division of Genetics, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa; (H.M.); (N.M.)
| | - Melvin Anyasi Ambele
- Institute for Cellular and Molecular Medicine, Department of Immunology and SAMRC Extramural Unit for Stem Cell Research and Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0001, South Africa;
- Department of Oral and Maxillofacial Pathology, School of Dentistry, Faculty of Health Sciences, University of Pretoria, Pretoria 0001, South Africa
| | - Ntlotlang Mokgautsi
- Division of Genetics, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa; (H.M.); (N.M.)
| | - Pontsho Moela
- Division of Genetics, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria 0002, South Africa; (H.M.); (N.M.)
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Ebrahimi M, Ebrahimi M, Vergroesen JE, Aschner M, Sillanpää M. Environmental exposures to cadmium and lead as potential causes of eye diseases. J Trace Elem Med Biol 2024; 82:127358. [PMID: 38113800 DOI: 10.1016/j.jtemb.2023.127358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/21/2023]
Abstract
Humans are exposed to cadmium and lead in various regions of the world daily due to industrial development and climate change. Increasing numbers of preclinical and clinical studies indicate that heavy metals, such as cadmium and lead, play a role in the pathogenesis of eye diseases. Excessive exposure to heavy metals such as cadmium and lead can increase the risk of impaired vision. Therefore, it is essential to better characterize the role of these non-essential metals in disease etiology and progression. This article discusses the potential role of cadmium and lead in the development of age-related eye diseases, including age-related macular degeneration, cataracts, and glaucoma. Furthermore, we discuss how cadmium and lead affect ocular cells and provide an overview of putative pathological mechanisms associated with their propensity to damage the eye.
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Affiliation(s)
- Moein Ebrahimi
- School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Network of Immunity in Infection, Malignancy, and Autoimmunity, Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Maryam Ebrahimi
- Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Tehran, Iran
| | - Joëlle E Vergroesen
- Department of Ophthalmology, Erasmus MC University Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands; Department of Epidemiology, Erasmus MC University Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands.
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Mika Sillanpää
- Department of Chemical Engineering, School of Mining, Metallurgy and Chemical Engineering, University of Johannesburg, P. O. Box 17011, Doornfontein 2028, South Africa; International Research Centre of Nanotechnology for Himalayan Sustainability (IRCNHS), Shoolini University, Solan 173212, Himachal Pradesh, India; Zhejiang Rongsheng Environmental Protection Paper Co. LTD, NO.588 East Zhennan Road, Pinghu Economic Development Zone, Zhejiang 314213, PR China; Department of Civil Engineering, University Centre for Research & Development, Chandigarh University, Gharuan, Mohali, Punjab, India
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3
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Knockdown of RBBP6 enhances radiosensitivity of gastric cancer cells through p53 pathway. Mol Cell Toxicol 2022. [DOI: 10.1007/s13273-022-00233-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Zhang S, Liu J, He J, Yi N. MicroRNA‑193a‑5p exerts a tumor suppressive role in epithelial ovarian cancer by modulating RBBP6. Mol Med Rep 2021; 24:582. [PMID: 34132380 PMCID: PMC8223108 DOI: 10.3892/mmr.2021.12221] [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: 04/03/2020] [Accepted: 06/26/2020] [Indexed: 12/16/2022] Open
Abstract
Epithelial ovarian cancer (EOC), a gynecological tumor, is associated with high mortality. MicroRNAs (miRs) serve a crucial role in EOC; however, the mechanisms underlying the effect of miRNA-193a-5p in EOC are not completely understood. Therefore, the present study aimed to investigate the expression levels of miR-193a-5p in serum samples of patients with EOC and to determine the role of miR-193a-5p in EOC. Reverse transcription-quantitative PCR was used to analyze the expression levels of miR-193a-5p in serum samples of patients with EOC and EOC cell lines. The effects of miR-193a-5p and RB binding protein 6, ubiquitin ligase (RBBP6) on the biological functions of EOC were determined by conducting a series of in vitro cell function experiments. The results indicated that the expression levels of miR-193a-5p were significantly decreased in serum samples obtained from patients with EOC and EOC cell lines compared with healthy individuals and normal cells, respectively. Further investigations indicated that RBBP6 was a target gene of miR-193a-5p. The expression levels of RBBP6 were significantly increased in patients with EOC compared with healthy individuals. In addition, in vitro analysis suggested that miR-193a-5p mimic significantly decreased SKOV3 cell proliferation, migration and invasion, and promoted SKOV3 cell apoptosis compared with the control and mimic-negative control groups. In addition, RBBP6 overexpression reversed miR-193a-5p mimic-mediated effects. In conclusion, the results of the present study suggested that downregulated expression levels of miR-193a-5p may serve an inhibitory role in EOC by inhibiting cell proliferation and metastasis, and promoting apoptosis.
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Affiliation(s)
- Shuangli Zhang
- Department of Gynecology, Beijing Ditan Hospital Capital Medical University, Beijing 100200, P.R. China
| | - Jun Liu
- Department of Gynecology, Beijing Ditan Hospital Capital Medical University, Beijing 100200, P.R. China
| | - Jie He
- Department of Gynecology, Beijing Liangxiang Hospital Capital Medical University, Beijing 100200, P.R. China
| | - Nuo Yi
- Department of Gynecology, Beijing Ditan Hospital Capital Medical University, Beijing 100200, P.R. China
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RBBP6 interactome: RBBP6 isoform 3/DWNN and Nek6 interaction is critical for cell cycle regulation and may play a role in carcinogenesis. INFORMATICS IN MEDICINE UNLOCKED 2021. [DOI: 10.1016/j.imu.2021.100522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Mosweu M, Motadi L, Moela P. Investigating the Effects of RBBP6 Gene Expression on Telomerase Activity in Cervical Cancer Cells. Cancer Manag Res 2020; 12:10725-10734. [PMID: 33149679 PMCID: PMC7605914 DOI: 10.2147/cmar.s261576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 09/03/2020] [Indexed: 12/24/2022] Open
Abstract
Background RBBP6 is one of the genes identified as a proliferative gene that plays a role in cancer development, On the other hand both RBBP6 and telomerase activity have been shown to be increase in various cancers. E6 protein of HPV and RBBP6 is known to enhance the progression of cancer cells by interacting with p53 and presenting it to be ubiquitinated by the proteasome thereby promoting cell proliferation and preventing apoptosis. Studies also show that HPV E6 protein can increase telomerase activity by activating the expression of human telomerase reverse transcriptase (hTERT), thus enabling the immortalization of the cells. With RBBP6 and hTERT showing a similar profile in cancer cells, we seek to investigate any possible effect of RBBP6 on telomerase activity. Results Using real-time qPCR and TRAPeze RT Telomerase detection kit (Merc) respectively. We used cervical cancer cell lines in which CaSki cell showed the reduction of hTERT expression and reduction in telomerase activity significantly in RBBP6-knockdown cells. While no significant changes were observed in HeLa cells. Real-time growth assay revealed a significant drop in cell growth in co-silenced RBBP6 and hTERT cells substantiating our observation that RBBP6 might be playing a role in cell proliferation. Conclusion Taken all together, the observed effect of RBBP6 gene silencing on telomerase activity in cervical cancer is cell line dependent.
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Affiliation(s)
- Mpho Mosweu
- University of Pretoria, Faculty of Natural and Agricultural Sciences, Department of Biochemistry, Hatfield, Pretoria 0002, South Africa
| | - Lesetja Motadi
- University of Johannesburg, Faculty of Science, Department of Biochemistry, Auckland Park Campus, Auckland Park, Johannesburg 2050, South Africa
| | - Pontsho Moela
- University of Pretoria, Faculty of Natural and Agricultural Sciences, Department of Biochemistry, Hatfield, Pretoria 0002, South Africa
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de Vries G, Rosas-Plaza X, Meersma GJ, Leeuwenburgh VC, Kok K, Suurmeijer AJH, van Vugt MATM, Gietema JA, de Jong S. Establishment and characterisation of testicular cancer patient-derived xenograft models for preclinical evaluation of novel therapeutic strategies. Sci Rep 2020; 10:18938. [PMID: 33144587 PMCID: PMC7641131 DOI: 10.1038/s41598-020-75518-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 08/03/2020] [Indexed: 12/11/2022] Open
Abstract
Testicular cancer (TC) is the most common solid tumour in young men. While cisplatin-based chemotherapy is highly effective in TC patients, chemoresistance still accounts for 10% of disease-related deaths. Pre-clinical models that faithfully reflect patient tumours are needed to assist in target discovery and drug development. Tumour pieces from eight TC patients were subcutaneously implanted in NOD scid gamma (NSG) mice. Three patient-derived xenograft (PDX) models of TC, including one chemoresistant model, were established containing yolk sac tumour and teratoma components. PDX models and corresponding patient tumours were characterised by H&E, Ki-67 and cyclophilin A immunohistochemistry, showing retention of histological subtypes over several passages. Whole-exome sequencing, copy number variation analysis and RNA-sequencing was performed on these TP53 wild type PDX tumours to assess the effects of passaging, showing high concordance of molecular features between passages. Cisplatin sensitivity of PDX models corresponded with patients' response to cisplatin-based chemotherapy. MDM2 and mTORC1/2 targeted drugs showed efficacy in the cisplatin sensitive PDX models. In conclusion, we describe three PDX models faithfully reflecting chemosensitivity of TC patients. These models can be used for mechanistic studies and pre-clinical validation of novel therapeutic strategies in testicular cancer.
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Affiliation(s)
- Gerda de Vries
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Ximena Rosas-Plaza
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Gert Jan Meersma
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Vincent C Leeuwenburgh
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Klaas Kok
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Albert J H Suurmeijer
- Department of Pathology, Cancer Research Center Groningen, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marcel A T M van Vugt
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Jourik A Gietema
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Steven de Jong
- Department of Medical Oncology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands.
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Rodríguez-Alonso A, Casas-Pais A, Roca-Lema D, Graña B, Romay G, Figueroa A. Regulation of Epithelial-Mesenchymal Plasticity by the E3 Ubiquitin-Ligases in Cancer. Cancers (Basel) 2020; 12:cancers12113093. [PMID: 33114139 PMCID: PMC7690828 DOI: 10.3390/cancers12113093] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/08/2020] [Accepted: 10/22/2020] [Indexed: 12/22/2022] Open
Abstract
The epithelial-mesenchymal plasticity (EMP) is a process by which epithelial cells acquire the ability to dynamically switch between epithelial and mesenchymal phenotypic cellular states. Epithelial cell plasticity in the context of an epithelial-to-mesenchymal transition (EMT) confers increased cell motility, invasiveness and the ability to disseminate to distant sites and form metastasis. The modulation of molecularly defined targets involved in this process has become an attractive therapeutic strategy against cancer. Protein degradation carried out by ubiquitination has gained attention as it can selectively degrade proteins of interest. In the ubiquitination reaction, the E3 ubiquitin-ligases are responsible for the specific binding of ubiquitin to a small subset of target proteins, and are considered promising anticancer drug targets. In this review, we summarize the role of the E3 ubiquitin-ligases that control targeted protein degradation in cancer-EMT, and we highlight the potential use of the E3 ubiquitin-ligases as drug targets for the development of small-molecule drugs against cancer.
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Affiliation(s)
- Andrea Rodríguez-Alonso
- Epithelial Plasticity and Metastasis Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Sergas, Universidade da Coruña (UDC), 15006 A Coruña, Spain; (A.R.-A.); (A.C.-P.); (D.R.-L.); (G.R.)
| | - Alba Casas-Pais
- Epithelial Plasticity and Metastasis Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Sergas, Universidade da Coruña (UDC), 15006 A Coruña, Spain; (A.R.-A.); (A.C.-P.); (D.R.-L.); (G.R.)
| | - Daniel Roca-Lema
- Epithelial Plasticity and Metastasis Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Sergas, Universidade da Coruña (UDC), 15006 A Coruña, Spain; (A.R.-A.); (A.C.-P.); (D.R.-L.); (G.R.)
| | - Begoña Graña
- Clinical Oncology Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Sergas, Universidade da Coruña (UDC), 15006 A Coruña, Spain;
| | - Gabriela Romay
- Epithelial Plasticity and Metastasis Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Sergas, Universidade da Coruña (UDC), 15006 A Coruña, Spain; (A.R.-A.); (A.C.-P.); (D.R.-L.); (G.R.)
| | - Angélica Figueroa
- Epithelial Plasticity and Metastasis Group, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Sergas, Universidade da Coruña (UDC), 15006 A Coruña, Spain; (A.R.-A.); (A.C.-P.); (D.R.-L.); (G.R.)
- Correspondence:
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Guan WY, Zhao S, Luo YN. Analysis of the expression and association of retinoblastoma binding protein 6 with the JNK signaling pathway in prostate cancers. Cell Biol Int 2020; 44:2107-2119. [PMID: 32662898 DOI: 10.1002/cbin.11419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 06/30/2020] [Accepted: 07/12/2020] [Indexed: 12/21/2022]
Abstract
This study aims to investigate the expression of retinoblastoma binding protein 6 (RBBP6) in prostate cancer (PCa) and its association with the c-Jun N-terminal kinase (JNK) pathway. Immunohistochemistry was used to detect RBBP6 and JNK1/2 expression in PCa and benign prostatic hyperplasia tissues. RBBP6 expression in PCa cells (LNCap, PC3, and DU145) and noncancerous prostate epithelial cells (RWPE-1) was determined by quantitative real-time polymerase chain reaction and western blot analysis. PC3 and DU145 cells were transfected with RBBP6 small interfering RNAs (siRNAs) to examine the biological characteristics. Anisomycin (a JNK activator) with/without RBBP6 siRNA was used to treat PC3 cells for further investigating the ramification of the RBBP6-mediated JNK pathway in PCa. PCa tissues and cells showed higher RBBP6 and JNK1/2 expression. RBBP6 was positively correlated with JNK1/2 in PCa tissues. Besides, RBBP6 expression was correlated to clinical tumor stage, lymph node metastasis, Gleason grade, preoperative prostate-specific antigen level, as well as prognosis of PCa. RBBP6 siRNA reduced cell proliferation, arrested cells at G2/M, and promoted cell apoptosis, and suppressed JNK pathway. In addition, migration and invasion decreased after the RBBP6 siRNA transfection with downregulated matrix metallopeptidase-2 (MMP-2) and MMP-9. Anisomycin promoted the proliferation, invasion, and migration of PC3 cells and inhibited PC3 cell apoptosis, which could be reversed by RBBP6 siRNA. RBBP6 expression was upregulated in PCa tissues and positively correlated with expression level of JNK1/2. With inhibition of RBBP6 expression, the proliferation, invasion, and migration of PCa cells decreased dramatically, while PC3 cell apoptosis increased appreciably, accompanied by the suppression of the JNK pathway.
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Affiliation(s)
- Wen-Ying Guan
- Myopia Laser Treatment Center, Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Sheng Zhao
- Department of Image Diagnostics, Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
| | - Yun-Na Luo
- Department of Physical Examination Center, Affiliated Hospital of Inner Mongolia Medical University, Hohhot, China
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Wang QS, Wei SR, Xiao HL. RBBP6 induces non-small cell lung cancer cell proliferation and high expression is associated with poor prognosis. Oncol Lett 2020; 19:2895-2901. [PMID: 32218844 PMCID: PMC7068609 DOI: 10.3892/ol.2020.11403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 01/07/2020] [Indexed: 12/02/2022] Open
Abstract
Lung cancer is the most common cause of cancer-associated mortality in China with 85% of patients having non-small cell lung cancer (NSCLC). Identifying NSCLC driver genes and prognostic markers is critical to reducing these numbers. The studies of retinoblastoma binding protein 6 (RBBP6) performed on NSCLC is limited. The present study aimed to investigate the molecular function and the prognostic potential of RBBP6 in NSCLC using the A549 cell line and patient samples, respectively. The functional effect on cancer cell proliferation and prognostic value of RBBP6 were examined in vitro and in vivo using reverse transcription-quantitative PCR, immunofluorescence, immunohistochemistry (IHC) and xenograft implantation. The results demonstrated that RBBP6 mRNA expression was significantly higher in NSCLC tissues compared with in adjacent normal samples. When RBBP6 mRNA expression was interfered with using short hairpin RNA, A549 cell proliferation and xenograft tumor growth were reduced. Additionally, IHC and survival analysis demonstrated that patients with NSCLC with high expression levels of RBBP6 had a shorter median overall survival time compared with patients with low RBBP6 expression (31 vs. 51.5 months), and this was more prominent in stage I–II patients (43 vs. >67 months). High expression levels of RBBP6 indicated poor prognosis in patients with NSCLC. This may be due to the ability of RBBP6 to promote cancer cell proliferation. RBBP6 may be a potential prognostic biomarker and a therapeutic target for NSCLC.
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Affiliation(s)
- Qiu-Shi Wang
- Department of Pathology, Daping Hospital and Research Institute of Surgery, Army Medical University, Chongqing 400042, P.R. China.,Department of Clinical Biobank, Daping Hospital and Research Institute of Surgery, Army Medical University, Chongqing 400042, P.R. China
| | - Shi-Rong Wei
- Department of Pathology, Daping Hospital and Research Institute of Surgery, Army Medical University, Chongqing 400042, P.R. China
| | - Hua-Liang Xiao
- Department of Pathology, Daping Hospital and Research Institute of Surgery, Army Medical University, Chongqing 400042, P.R. China
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RBBP6, a RING finger-domain E3 ubiquitin ligase, induces epithelial-mesenchymal transition and promotes metastasis of colorectal cancer. Cell Death Dis 2019; 10:833. [PMID: 31685801 PMCID: PMC6828677 DOI: 10.1038/s41419-019-2070-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 10/09/2019] [Accepted: 10/14/2019] [Indexed: 12/11/2022]
Abstract
RBBP6 has been implicated in tumorigenesis but its role in tumor metastasis and progression has not been evaluated. Interestingly, here we show that RBBP6 is upregulated in colorectal cancer (CRC) where its expression level is positively correlated with distant metastasis. In this study, we identified RBBP6, a RING Finger-domain E3 ubiquitin ligase, served as an independent prognostic factor and predicted poor outcome for CRC patients. RBBP6 promoted cell proliferation, migration, and invasion in CRC cells and promoted tumor growth, lung metastasis, and liver metastasis in mouse models. Mechanistically, we revealed that RBBP6 bound and ubiquitylated IκBα, an inhibitor of the NF-κB-signaling pathway. RBBP6-mediated ubiquitination and degradation of IκBα significantly enhanced p65 nuclear translocation, which triggered the activation of NF-κB pathway and then induced the epithelial–mesenchymal transition (EMT) process and cell metastasis. Furthermore, by DNA methylation results and ChIP analysis, we demonstrated that the promoter of RBBP6 was hypomethylated, and was activated by multi-oncogenic transcription factors. In conclusion, our findings suggest that RBBP6 may be a potential prognostic biomarker and therapeutic target for CRC invasion and metastasis.
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Makgoo L, Laka K, Mbita Z. Downregulation of RBBP6 variant 1 during arsenic trioxide-mediated cell cycle arrest and curcumin-induced apoptosis in MCF-7 breast cancer cells. Future Sci OA 2019; 5:FSO409. [PMID: 31534777 PMCID: PMC6745614 DOI: 10.2144/fsoa-2019-0047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Aim To determine the expression patterns of the RBBP6 spliced variants during arsenic trioxide-mediated cell cycle arrest and curcumin-induced apoptosis in MCF-7 cells. Materials & methods As2O3 and curcumin were used to study cytotoxicity, cell cycle arrest, apoptosis and the expression of RBBP6 variants. The MUSE Cell Analyser was used to analyze cell cycle arrest, apoptosis and multicaspase activity while apoptosis was further confirmed using microscopy. Semi-quantitative RT-PCR was employed to quantitate the expression of the RBBP6 variants. Results This study showed that the MCF-7 cells expressed RBBP6 variant 1 but lacked both variant 2 and variant 3. Both As2O3 and curcumin significantly downregulated RBBP6 variant 1 (p < 0.001). Conclusion RBBP6 variants are promising therapeutic targets.
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Affiliation(s)
- Lilian Makgoo
- Department of Biochemistry, Microbiology, & Biotechnology, University of Limpopo, Private Bag x1106, Sovenga, 0727, Polokwane, South Africa
| | - Kagiso Laka
- Department of Biochemistry, Microbiology, & Biotechnology, University of Limpopo, Private Bag x1106, Sovenga, 0727, Polokwane, South Africa
| | - Zukile Mbita
- Department of Biochemistry, Microbiology, & Biotechnology, University of Limpopo, Private Bag x1106, Sovenga, 0727, Polokwane, South Africa
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Dlamini Z, Ledwaba T, Hull R, Naicker S, Mbita Z. RBBP6 Is Abundantly Expressed in Human Cervical Carcinoma and May Be Implicated in Its Malignant Progression. BIOMARKERS IN CANCER 2019; 11:1179299X19829149. [PMID: 30886526 PMCID: PMC6415476 DOI: 10.1177/1179299x19829149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 01/16/2019] [Indexed: 01/18/2023]
Abstract
RBBP6 is a novel gene encoding splicing-associated proteins. There are 3 protein isoforms (isoforms 1-3). RBBP6 isoforms 1 has been shown to interact with both p53 and Rb. It also plays a role in the induction of apoptosis and the regulation of the cell cycle. The expression of RBBP6 has been documented in several cancers but RBBP6 expression in cervical cancer has not been well studied. The aim of this study was to establish expression levels and tissue distribution of the RBBP6 gene products at both protein and messenger RNA (mRNA) levels in cervical cancer by immunocytochemistry and in situ hybridization (ISH). A link between RBBP6 expression, apoptosis, and cervical cancer progression was also investigated. RBBP6 mRNA was expressed in the nuclei and cytoplasm of normal and tumour cervical epithelium. In general, expression was high in the cytoplasm and nuclei of moderately differentiated and invasive carcinoma. Immunolabelling results were confirmed by image analysis and ISH experiments. Apoptosis assays using TUNEL correlated with the expression of the RBBP6 gene in all examined cases. This is the first report on the abundant expression of RBBP6 in cervical cancer and its involvement in the malignant progression of cervical cancer. Because of the high expression and corresponding pro-apoptotic activity observed in cervical cancer cells in this study, we suggest that RBBP6 is involved in the malignant progression of cervical cancer. RBBP6 proteins can therefore be targeted for therapeutic interventions against cervical cancer.
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Affiliation(s)
- Zodwa Dlamini
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban, South Africa
| | - Thokozile Ledwaba
- National Institute for Communicable Diseases, Centre for HIV and STIs, Johannesburg, South Africa
| | - Rodney Hull
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban, South Africa
| | - Sarala Naicker
- Faculty of Health Sciences, Wits Medical School, Parktown, South Africa
| | - Zukile Mbita
- Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Sovenga, South Africa
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14
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Yang X, Zhang Q, Yang X, Zhao M, Yang T, Yao A, Tian X. PACT cessation overcomes ovarian cancer cell chemoresistance to cisplatin by enhancing p53-mediated apoptotic pathway. Biochem Biophys Res Commun 2019; 511:719-724. [PMID: 30827507 DOI: 10.1016/j.bbrc.2019.02.089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 02/16/2019] [Indexed: 12/18/2022]
Abstract
Ovarian cancer ranks as a lethal gynecological malignancy, and development of resistance to chemotherapy agents constitutes a major clinical challenge in ovarian carcinoma management. P53-associated cellular protein-testes derived (PACT) is recently proven to be expressed aberrantly in several cancers, and exerts a critical roles in cell proliferation, apoptosis and migration. Up to now, its function in chemoresistance of ovarian cancer remains poorly defined. In the present study, elevated expression of PACT was detected in cisplatin-resistant A2780/CP cells relative to cisplatin-sensitive A2780 cells. Moreover, exposure to cisplatin also increased PACT expression in A2780 cells. Functional assay confirmed that knockdown of PACT further aggravated the inhibitory effects of cisplatin on A2780 cell viability and enhanced cell apoptosis and caspase-3 activity in cisplatin-treated A2780 cells, indicating that PACT cessation elevates cell sensitivity to cisplatin in A2780 cells. Whilst, deletion of PACT affords little effects on cisplatin resistance in p53-defective SKOV3 cells. Mechanistic analysis corroborated that depression of PACT notably enhanced cisplatin-induced p53 expression, concomitant with the increases in p53-downstream Bax, p21 expression and decrease in Bcl-2 expression. Intriguingly, blocking the p53 pathway notably reversed PACT inhibition-increased cell sensitivity to cisplatin in A2780 cells by elevating cell viability and depressing cell apoptosis. Additionally, abrogation of p53 signaling also blunts PACT suppression-overcomed chemotherapy resistance to cisplatin in A2780/CP cells. Together, these findings confirm that targeting PACT may antagonize ovarian cancer cell resistance to cisplatin, supporting a promising therapeutic strategy to overcome the chemotherapy resistance in the treatment of ovarian cancer.
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Affiliation(s)
- Xuemei Yang
- Department of the Second of Gynecologic Oncology, Shaanxi Provincial Tumor Hospital, The Affiliated Hospital of Medical College of Xi'an JiaoTong University, Xi'an, Shannxi, 710061, PR China
| | - Qian Zhang
- Department of the First of Internal Medicine, Shaanxi Provincial Tumor Hospital, The Affiliated Hospital of Medical College of Xi'an JiaoTong University, Xi'an, Shannxi, 710061, PR China
| | - Xiaofeng Yang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, PR China.
| | - Minyi Zhao
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, PR China
| | - Ting Yang
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, PR China
| | - Anmei Yao
- Department of the Second of Gynecologic Oncology, Shaanxi Provincial Tumor Hospital, The Affiliated Hospital of Medical College of Xi'an JiaoTong University, Xi'an, Shannxi, 710061, PR China
| | - Xiaofei Tian
- Department of the Second of Gynecologic Oncology, Shaanxi Provincial Tumor Hospital, The Affiliated Hospital of Medical College of Xi'an JiaoTong University, Xi'an, Shannxi, 710061, PR China
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15
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Teng F, Ruan HJ, Xu J, Ni J, Qian B, Shen R, Gao LJ. RBBP6 promotes human cervical carcinoma malignancy via JNK signaling pathway. Biomed Pharmacother 2018; 101:399-405. [DOI: 10.1016/j.biopha.2018.02.083] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 02/08/2018] [Accepted: 02/19/2018] [Indexed: 02/06/2023] Open
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16
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Xiao C, Wang Y, Zheng M, Chen J, Song G, Zhou Z, Zhou C, Sun X, Zhong L, Ding E, Zhang Y, Yang L, Wu G, Xu S, Zhang H, Wang X. RBBP6 increases radioresistance and serves as a therapeutic target for preoperative radiotherapy in colorectal cancer. Cancer Sci 2018; 109:1075-1087. [PMID: 29369481 PMCID: PMC5891205 DOI: 10.1111/cas.13516] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 01/15/2018] [Accepted: 01/21/2018] [Indexed: 01/15/2023] Open
Abstract
Radiotherapy (RT) can be used as preoperative treatment to downstage initially unresectable locally rectal carcinoma, but radioresistance and recurrence remain significant problems. Retinoblastoma binding protein 6 (RBBP6) has been implicated in the regulation of cell cycle, apoptosis and chemoresistance both in vitro and in vivo. The present study investigated whether the inhibition of RBBP6 expression would improve radiosensitivity in human colorectal cancer cells. After SW620 and HT29 cells were exposed to radiation, the levels of RBBP6 mRNA and protein increased over time in both cells. Moreover, a significant reduction in clonogenic survival and a decrease in cell viability in parallel with an obvious increase in cell apoptosis were demonstrated in irradiated RBBP6‐knockdown cells. Transfection with RBBP6 shRNA improved the levels of G2‐M phase arrest, which blocked the cells in a more radiosensitive period of the cell cycle. These observations indicated that cell cycle and apoptosis mechanisms may be connected with tumor cell survival following radiotherapy. In vivo, the tumor growth rate of nude mice in the RBBP6‐knockdown group was significantly slower than that in other groups. These results indicated that RBBP6 overexpression could resist colorectal cancer cells against radiation by regulating cell cycle and apoptosis pathways, and inhibition of RBBP6 could enhance radiosensitivity of human colorectal cancer.
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Affiliation(s)
- Chao Xiao
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yupeng Wang
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Miao Zheng
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jian Chen
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Guohe Song
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zhijie Zhou
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chongzhi Zhou
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xing Sun
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lin Zhong
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Erxun Ding
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yi Zhang
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Liu Yang
- Department of Obstetrics and Gynecology, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Gang Wu
- Department of General Surgery, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Shifeng Xu
- Department of General Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, China
| | - Hong Zhang
- School of Medicine, Örebro University, Örebro, Sweden
| | - Xiaoliang Wang
- Department of General Surgery, Shanghai General Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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17
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Varghese VK, Shukla V, Kabekkodu SP, Pandey D, Satyamoorthy K. DNA methylation regulated microRNAs in human cervical cancer. Mol Carcinog 2017; 57:370-382. [PMID: 29077234 DOI: 10.1002/mc.22761] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 10/17/2017] [Accepted: 10/23/2017] [Indexed: 01/19/2023]
Abstract
Regulation of miRNA gene expression by DNA promoter methylation may represent a key mechanism to drive cervical cancer progression. In order to understand the impact of DNA promoter methylation on miRNAs at various stages of cervical carcinogenesis, we performed DNA methylation microarray on Normal Cervical Epithelium (NCE), Cervical Intraepithelial Neoplasia (CIN I-III) and Squamous Cell Carcinoma (SCC) tissues to identify differentially methylated miRNAs followed by validation by bisulfite sequencing. Further, expression of miRNAs was analyzed by qRT-PCR in clinical tissues and cervical cancer cell lines. Transcriptional activity was determined by luciferase assay. We identified a total of 69 hypermethylated and hypomethylated miRNA promoters encompassing 78 CpG islands in all except Y chromosome, among the three groups. The candidate DNA promoters of miR-424 were significantly hypermethylated and miR-200b and miR-34c were significantly hypomethylated in SCC compared to NCE (P < 0.05). Expression of miR-424, miR-200b, and miR-34c were inversely correlated with promoter DNA methylation in tissue samples. Treatment of cell lines with 5-aza-2'-deoxycytidine showed differential expression in all three miRNAs. We observed a decrease in miRNA promoter activity following in vitro SssI methylase treatment of miR-424, miR-200b, and miR-34c. Luciferase assay demonstrated that miR-200b and miR-424 functionally interacts with 3'-UTR of HIPK3 and RBBP6 respectively and decreased their activity in presence of miR-200b and miR-424 mimics transfected in SiHa cells. Taken together, we have identified deregulation of miRNAs by aberrant DNA promoter methylation, leading to its transcriptional silencing during cervical carcinogenesis, which can be potential targets for diagnosis and therapy.
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Affiliation(s)
- Vinay K Varghese
- Department of Cell and Molecular Biology, School of Life Sciences, Manipal University, Manipal, Karnataka, India
| | - Vaibhav Shukla
- Department of Cell and Molecular Biology, School of Life Sciences, Manipal University, Manipal, Karnataka, India
| | - Shama P Kabekkodu
- Department of Cell and Molecular Biology, School of Life Sciences, Manipal University, Manipal, Karnataka, India
| | - Deeksha Pandey
- Department of Obstetrics and Gynecology, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
| | - Kapaettu Satyamoorthy
- Department of Cell and Molecular Biology, School of Life Sciences, Manipal University, Manipal, Karnataka, India
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18
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Vinayanuwattikun C, Le Calvez-Kelm F, Abedi-Ardekani B, Zaridze D, Mukeria A, Voegele C, Vallée M, Purnomosari D, Forey N, Durand G, Byrnes G, Mckay J, Brennan P, Scelo G. Elucidating Genomic Characteristics of Lung Cancer Progression from In Situ to Invasive Adenocarcinoma. Sci Rep 2016; 6:31628. [PMID: 27545006 PMCID: PMC4992872 DOI: 10.1038/srep31628] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 07/19/2016] [Indexed: 01/09/2023] Open
Abstract
To examine the diversity of somatic alterations and clonal evolution according to aggressiveness of disease, nineteen tumor-blood pairs of 'formerly bronchiolo-alveolar carcinoma (BAC)' which had been reclassified into preinvasive lesion (adenocarcinoma in situ; AIS), focal invasive lesion (minimally invasive adenocarcinoma; MIA), and invasive lesion (lepidic predominant adenocarcinoma; LPA and non-lepidic predominant adenocarcinoma; non-LPA) according to IASLC/ATS/ERS 2011 classification were explored by whole exome sequencing. Several distinct somatic alterations were observed compare to the lung adenocarcinoma study from the Cancer Genome Atlas (TCGA). There were higher numbers of tumors with significant APOBEC mutation fold enrichment (73% vs. 58% TCGA). The frequency of KRAS mutations was lower in our study (5% vs. 32% TCGA), while a higher number of mutations of RNA-splicing genes, RBM10 and U2AF1, were found (37% vs. 11% TCGA). We found neither mutational pattern nor somatic copy number alterations that were specific to AIS/MIA. We demonstrated that clonal cell fraction was the only distinctive feature that discriminated LPA/non-LPA from AIS/MIA. The broad range of clonal frequency signified a more branched clonal evolution at the time of diagnosis. Assessment of tumor clonal cell fraction might provide critical information for individualized therapy as a prognostic factor, however this needs further study.
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Affiliation(s)
- Chanida Vinayanuwattikun
- International Agency for Research on Cancer, Lyon, France
- Division of Medical Oncology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and The King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | | | | | - David Zaridze
- Russian N.N. Blokhin Cancer Research Centre, Moscow, Russian Federation
| | - Anush Mukeria
- Russian N.N. Blokhin Cancer Research Centre, Moscow, Russian Federation
| | | | - Maxime Vallée
- International Agency for Research on Cancer, Lyon, France
- Department of Molecular Medicine, CHUQ Research Center, Laval University, Quebec, Canada
| | - Dewajani Purnomosari
- International Agency for Research on Cancer, Lyon, France
- Department of Histology and Cell Biology and Molecular Biology Laboratory, Faculty of Medicine, Gadjah Mada University, Yogyakarta, Indonesia
| | - Nathalie Forey
- International Agency for Research on Cancer, Lyon, France
| | | | - Graham Byrnes
- International Agency for Research on Cancer, Lyon, France
| | - James Mckay
- International Agency for Research on Cancer, Lyon, France
| | - Paul Brennan
- International Agency for Research on Cancer, Lyon, France
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19
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Moela P, Motadi LR. RBBP6: a potential biomarker of apoptosis induction in human cervical cancer cell lines. Onco Targets Ther 2016; 9:4721-35. [PMID: 27536134 PMCID: PMC4973719 DOI: 10.2147/ott.s100964] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Overexpression of RBBP6 in cancers of the colon, lung, and esophagus makes it a potential target in anticancer therapy. This is especially important because RBBP6 associates with the tumor suppressor gene p53, the inactivation of which has been linked to over 50% of all cancer types. However, the expression of RBBP6 in cancer and its interaction with p53 are yet to be understood in order to determine whether or not RBBP6 is cancer promoting and therefore a potential biomarker. In this study, we manipulated RBBP6 expression levels followed by treatment with either camptothecin or γ-aminobutyric acid in cervical cancer cells to induce apoptosis or cell cycle arrest. We began by staining human cervical cancer tissue sections with anti-RBBP6 monoclonal antibody to evaluate the extent of expression of RBBP6 in patients’ specimens. We followed on with silencing the overexpression of RBBP6 and treatment with anticancer agents to evaluate how the specimens respond to combinational therapy. Apoptosis induction was evaluated through confocal microscope, and flow cytometry using annexin V staining, and also by checking the mitochondrial and caspase-3/7 activity. Cell cycle arrest was evaluated using flow cytometry through staining with propidium iodide. RBBP6 was highly expressed in cervical cancer tissue sections that were in stage II or III of development. Silencing RBBP6 followed by treatment with γ-aminobutyric acid and camptothecin seems to sensitize cells to apoptosis induction rather than cell cycle arrest. Overexpression of RBBP6 seems to promote S-phase in cell cycle and cell proliferation. These results predict a proliferative role of RBBP6 in cancer progression rather than as a cancer-causing gene. Furthermore, sensitization of cells to camptothecin-induced apoptosis by RBBP6 targeting suggests a promising tool for halting cervical cancer progression.
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Affiliation(s)
- Pontsho Moela
- Department of Biochemistry, North-West University, Potchefstroom, South Africa
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20
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Dlamini Z, Rupnarain C, Naicker S, Hull R, Mbita Z. Expression analysis and association of RBBP6 with apoptosis in colon cancers. J Mol Histol 2016; 47:169-82. [DOI: 10.1007/s10735-016-9663-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/11/2016] [Indexed: 10/22/2022]
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21
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Masuda D, Masuda R, Matsuzaki T, Imamura N, Aruga N, Tanaka M, Inokuchi S, Kijima H, Iwazaki M. Ki-67 labeling index affects tumor infiltration patterns of lung squamous cell carcinoma. Mol Med Rep 2015; 12:7303-9. [PMID: 26459875 PMCID: PMC4626199 DOI: 10.3892/mmr.2015.4354] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 01/09/2015] [Indexed: 12/21/2022] Open
Abstract
Ki-67 is a nuclear protein that is expressed during the G1, S, G2 and M phases of the mitotic cell cycle. A previous study categorized tumor infiltration patterns (INF), of which INFc indicated cancer nests exhibiting infiltrative growth and an unclear boundary between tumor tissue and surrounding healthy tissue. The present study used the Ki-67 labeling index (Ki-67 LI) as an indicator of cell proliferation, in order to examine the factors affecting INF in lung squamous cell carcinoma (SqCC). SqCC specimens (89) were classified into two groups: High-grade cell proliferation (Ki-67 LI ≥30%) and low-grade cell proliferation (Ki-67 LI <30%). However, a high Ki-67 LI was significantly associated with cases that had an INFc component [INFc(+); P=0.03]. Univariate analyses indicated that INFc(+) was a predictor of venous invasion [P=0.032; odds ratio (OR), 2.615; 95% confidence interval (95% CI), 1.085–6.305], scirrhous stromal type (P<0.001; OR, 6.462; 95% CI, 2.483–16.817) and high Ki-67 LI (P=0.018; OR, 12.543; 95% CI, 1.531–102.777). Multivariate logistic analyses indicated that high Ki-67 LI was the strongest predictor of INFc(+) (P=0.028; OR, 8.027; 95% CI, 1.248–51.624). In conclusion, high-grade cell proliferation activity may contribute to aggressive infiltrative growth of lung SqCC.
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Affiliation(s)
- Daisuke Masuda
- Department of General Thoracic Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259‑1193, Japan
| | - Ryota Masuda
- Department of General Thoracic Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259‑1193, Japan
| | - Tomohiko Matsuzaki
- Department of General Thoracic Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259‑1193, Japan
| | - Naoko Imamura
- Department of General Thoracic Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259‑1193, Japan
| | - Naohiro Aruga
- Department of General Thoracic Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259‑1193, Japan
| | - Makiko Tanaka
- Department of Pathology and Bioscience, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori 036‑8562, Japan
| | - Sadaki Inokuchi
- Department of Pathology and Bioscience, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori 036‑8562, Japan
| | - Hiroshi Kijima
- Department of Pathology and Bioscience, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori 036‑8562, Japan
| | - Masayuki Iwazaki
- Department of General Thoracic Surgery, Tokai University School of Medicine, Isehara, Kanagawa 259‑1193, Japan
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22
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Hull R, Oosthuysen B, Cajee UF, Mokgohloa L, Nweke E, Antunes RJ, Coetzer THT, Ntwasa M. The Drosophila retinoblastoma binding protein 6 family member has two isoforms and is potentially involved in embryonic patterning. Int J Mol Sci 2015; 16:10242-66. [PMID: 25955646 PMCID: PMC4463644 DOI: 10.3390/ijms160510242] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 03/13/2015] [Indexed: 12/16/2022] Open
Abstract
The human retinoblastoma binding protein 6 (RBBP6) is implicated in esophageal, lung, hepatocellular and colon cancers. Furthermore, RBBP6 was identified as a strong marker for colon cancer prognosis and as a predisposing factor in familial myeloproliferative neoplasms. Functionally, the mammalian protein interacts with p53 and enhances the activity of Mdm2, the prototypical negative regulator of p53. However, since RBBP6 (known as PACT in mice) exists in multiple isoforms and pact-/- mice exhibit a more severe phenotype than mdm2-/- mutants, it must possess some Mdm2-independent functions. The function of the invertebrate homologue is poorly understood. This is complicated by the absence of the Mdm2 gene in both Drosophila and Caenorhabditis elegans. We have experimentally identified the promoter region of Snama, the Drosophila homologue, analyzed potential transcription factor binding sites and confirmed the existence of an additional isoform. Using band shift and co-immunoprecipitation assays combined with mass spectrometry, we found evidence that this gene may be regulated by, amongst others, DREF, which regulates hundreds of genes related to cell proliferation. The potential transcription factors for Snama fall into distinct functional groups, including anteroposterior embryonic patterning and nucleic acid metabolism. Significantly, previous work in mice shows that pact-/- induces an anteroposterior phenotype in embryos when rescued by simultaneous deletion of p53. Taken together, these observations indicate the significance of RBBP6 proteins in carcinogenesis and in developmental defects.
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Affiliation(s)
- Rodney Hull
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
| | - Brent Oosthuysen
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
| | - Umar-Faruq Cajee
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
| | - Lehlogonolo Mokgohloa
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
| | - Ekene Nweke
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
| | - Ricardo Jorge Antunes
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
| | - Theresa H T Coetzer
- School of Life Sciences, University of KwaZulu-Natal (Pietermaritzburg campus); 3209 Scottsville, South Africa.
| | - Monde Ntwasa
- School of Molecular & Cell Biology, University of the Witwatersrand, Johannesburg, South Africa Private Bag 3, WITS-2050 Johannesburg, South Africa.
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23
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Mbita Z, Naicker S, Goetsch S, Dlamini Z. The association of RBBP6 variant 3 expressions with apoptosis in human immunodeficiency virus-associated nephropathy (HIVAN). Exp Mol Pathol 2015; 99:74-80. [PMID: 25910411 DOI: 10.1016/j.yexmp.2015.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 04/18/2015] [Indexed: 11/25/2022]
Abstract
South Africa has one of the highest HIV infection rates in the world. One of the complications of HIV infection is the development of HIV-associated nephropathy (HIVAN), which is characterized by deregulation in tubular epithelial apoptosis. The pathways that HIV-1 promotes in the pathogenesis of HIVAN remain less understood. There are many genes that have not been characterized in the pathogenesis of HIVAN. On the other hand, RBBP6 has been shown to play a role in both promoting and inhibiting apoptosis in human cancers. This study was aimed at determining an association between RBBP6 isoform 3 expression and the levels of apoptosis in HIVAN cases. HIVAN biopsy tissues from Johannesburg patients in South Africa were used in this study. These tissues were stained for RBBP6 expression and apoptosis levels using immunohistochemistry staining and TUNEL method respectively. Image analysis was used for quantitative analysis and GraphPad Version 4 was used for statistical analysis. High expression levels of RBBP6 were found in HIVAN cases (n=30) relative to the normal tissues (n=10). High apoptosis levels were also obtained in the HIVAN tissues. This direct association between RBBP6 expression and apoptosis levels suggests that RBBP6 may play a role in HIVAN pathogenesis. RBBP6 may then be targeted for both diagnostic and therapeutic strategies in HIVAN.
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Affiliation(s)
- Zukile Mbita
- Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Private Bag X 1106, Sovenga 0727, South Africa
| | - Sarala Naicker
- Faculty of Health Sciences, Wits Medical School, 7 York Road, Parktown, 2193, South Africa
| | - Stewart Goetsch
- Faculty of Health Sciences, Wits Medical School, 7 York Road, Parktown, 2193, South Africa
| | - Zodwa Dlamini
- Research, Innovation & Engagements Portfolio, Mangosuthu University of Technology, Durban, 4031, South Africa.
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24
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Di Giammartino DC, Li W, Ogami K, Yashinskie JJ, Hoque M, Tian B, Manley JL. RBBP6 isoforms regulate the human polyadenylation machinery and modulate expression of mRNAs with AU-rich 3' UTRs. Genes Dev 2014; 28:2248-60. [PMID: 25319826 PMCID: PMC4201286 DOI: 10.1101/gad.245787.114] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Campigli Di Giammartino et al. find that RBBP6 is a component of a large multisubunit protein complex that mediates polyadenylation of mRNA precursors. Genome-wide analyses following RBBP6 knockdown revealed decreased transcript levels, especially of mRNAs with AU-rich 3′ UTRs such as c-Fos and c-Jun, and increased usage of distal poly(A) sites. Polyadenylation of mRNA precursors is mediated by a large multisubunit protein complex. Here we show that RBBP6 (retinoblastoma-binding protein 6), identified initially as an Rb- and p53-binding protein, is a component of this complex and functions in 3′ processing in vitro and in vivo. RBBP6 associates with other core factors, and this interaction is mediated by an unusual ubiquitin-like domain, DWNN (“domain with no name”), that is required for 3′ processing activity. The DWNN is also expressed, via alternative RNA processing, as a small single-domain protein (isoform 3 [iso3]). Importantly, we show that iso3, known to be down-regulated in several cancers, competes with RBBP6 for binding to the core machinery, thereby inhibiting 3′ processing. Genome-wide analyses following RBBP6 knockdown revealed decreased transcript levels, especially of mRNAs with AU-rich 3′ untranslated regions (UTRs) such as c-Fos and c-Jun, and increased usage of distal poly(A) sites. Our results implicate RBBP6 and iso3 as novel regulators of 3′ processing, especially of RNAs with AU-rich 3′ UTRs.
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Affiliation(s)
| | - Wencheng Li
- Department of Biochemistry and Molecular Biology, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
| | - Koichi Ogami
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Jossie J Yashinskie
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Mainul Hoque
- Department of Biochemistry and Molecular Biology, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
| | - Bin Tian
- Department of Biochemistry and Molecular Biology, Rutgers New Jersey Medical School, Newark, New Jersey 07103, USA
| | - James L Manley
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA;
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25
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Rosvall KA, Peterson MP. Behavioral effects of social challenges and genomic mechanisms of social priming: What's testosterone got to do with it? Curr Zool 2014; 60:791-803. [PMID: 27721823 DOI: 10.1093/czoolo/60.6.791] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Social challenges from rival conspecifics are common in the lives of animals, and changes in an animal's social environment can influence physiology and behavior in ways that appear to be adaptive in the face of continued social instability (i.e. social priming). Recently, it has become clear that testosterone, long thought to be the primary mediator of these effects, may not always change in response to social challenges, an observation that highlights gaps in our understanding of the proximate mechanisms by which animals respond to their social environment. Here, our goal is to address the degree to which testosterone mediates organismal responses to social cues. To this end, we review the behavioral and physiological consequences of social challenges, as well as their underlying hormonal and gene regulatory mechanisms. We also present a new case study from a wild songbird, the dark-eyed junco (Junco hyemalis), in which we find largely divergent genome-wide transcriptional changes induced by social challenges and testosterone, respectively, in muscle and liver tissue. Our review underscores the diversity of mechanisms that link the dynamic social environment with an organisms' genomic, hormonal, and behavioral state. This diversity among species, and even among tissues within an organism, reveals new insights into the pattern and process by which evolution may alter proximate mechanisms of social priming.
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Affiliation(s)
- Kimberly A Rosvall
- Indiana University, Department of Biology and Center for the Integrative Study of Animal Behavior
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Hu D, Zhang S, Zhao Y, Wang S, Wang Q, Song X, Lu D, Mao Y, Chen H. Association of genetic variants in the retinoblastoma binding protein 6 gene with the risk of glioma: a case-control study in a Chinese Han population. J Neurosurg 2014; 121:1209-18. [PMID: 25127414 DOI: 10.3171/2014.6.jns132240] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The retinoblastoma binding protein 6 (RBBP6) gene plays an important role in the induction of apoptosis and regulation of the cell cycle, and interacts with both p53 and retinoblastoma protein in carcinogenesis. Recently, many studies investigating the function of the RBBP6 gene, including its roles in lung cancer and breast cancer, have been reported. However, the association between RBBP6 variants and glioma was unknown. Therefore, to uncover the association between single nucleotide polymorphisms (SNPs) of RBBP6 and glioma, a hospital-based case-control study was performed in a Chinese Han population. METHODS Ten common tagging SNPs of the RBBP6 gene (covering 100% of all SNPs) were genotyped with the Sequenom MassARRY iPLEX platform, including 992 cases and 1008 controls, according to the HapMap database based on a pairwise linkage disequilibrium r(2) threshold of 0.8, minor allele frequency of 0.05, and Hardy-Weinberg equilibrium of 0.05. RESULTS The authors found that 4 SNPs were significantly associated with glioma (rs2033214, p = 0.013, adjusted OR 2.46, 95% CI 1.18-5.14; rs11860248, p = 8.64 × 10-(6), adjusted OR 1.59, 95% CI 1.23-2.05; rs9933544, p = 3.65 × 10(-4), adjusted OR 1.39, 95% CI 1.13-1.87; rs13332653, p = 0.004, adjusted OR 1.49, 95% CI 1.14-1.95). Stratification analyses revealed that rs2033214 was only significantly associated with low-grade gliomas; rs9933544 and rs13332653 were only significantly associated with glioblastoma multiforme; and rs11860248 was significantly associated with both low-grade gliomas and glioblastoma multiforme, compared with the common wild-type homozygous genotype. Further stratified analysis revealed that rs11860248 was more pronounced in certain subgroups: adults, males, histological types, and family history of cancer. What's more, the haplotype and diplotype analyses consistently revealed that the subjects carrying 1 copy of haplotype CCGCC had a 53% increased glioma risk compared with their corresponding noncarriers (p = 0.018, adjusted OR 1.53, 95% CI 1.08-2.17). CONCLUSIONS The authors' results suggested that RBBP6 gene variants are associated with glioma and contribute to glioma susceptibility, which was first reported elsewhere. Individuals with the so-called risk alleles might have an increased risk of glioma. These results might provide new insight into the occurrence of glioma.
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Affiliation(s)
- Dezhi Hu
- State Key Laboratory of Genetic Engineering, Fudan-VARI Genetic Epidemiology Center and MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences andInstitutes for Biomedical Sciences, Fudan University, and
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Mthembu NN, Motadi LR. Apoptotic potential role of Agave palmeri and Tulbaghia violacea extracts in cervical cancer cells. Mol Biol Rep 2014; 41:6143-55. [DOI: 10.1007/s11033-014-3493-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 06/17/2014] [Indexed: 01/22/2023]
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The RBBP6/ZBTB38/MCM10 axis regulates DNA replication and common fragile site stability. Cell Rep 2014; 7:575-587. [PMID: 24726359 DOI: 10.1016/j.celrep.2014.03.030] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 01/17/2014] [Accepted: 03/09/2014] [Indexed: 11/23/2022] Open
Abstract
Faithful DNA replication is essential for the maintenance of genome integrity. Incomplete genome replication leads to DNA breaks and chromosomal rearrangements, which are causal factors in cancer and other human diseases. Despite their importance, the molecular mechanisms that control human genome stability are incompletely understood. Here, we report a pathway that is required for human genome replication and stability. This pathway has three components: an E3 ubiquitin ligase, a transcriptional repressor, and a replication protein. The E3 ubiquitin ligase RBBP6 ubiquitinates and destabilizes the transcriptional repressor ZBTB38. This repressor negatively regulates transcription and levels of the MCM10 replication factor on chromatin. Cells lacking RBBP6 experience reduced replication fork progression and increased damage at common fragile sites due to ZBTB38 accumulation and MCM10 downregulation. Our results uncover a pathway that ensures genome-wide DNA replication and chromosomal stability.
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Moela P, Choene MMS, Motadi LR. Silencing RBBP6 (Retinoblastoma Binding Protein 6) sensitises breast cancer cells MCF7 to staurosporine and camptothecin-induced cell death. Immunobiology 2014; 219:593-601. [PMID: 24703106 DOI: 10.1016/j.imbio.2014.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/27/2014] [Accepted: 03/12/2014] [Indexed: 12/23/2022]
Abstract
Retinoblastoma Binding Protein 6 (RBBP6) is a multi-domain protein that uses its ring finger domain to interact with p53 and pRb tumour suppressor genes. The mechanism by which RBBP6 uses to degrade p53 is still unknown; nonetheless it is well known that RBBP6 promotes cell proliferation in several cancers by negatively regulating p53 via its E3 ubiquitin ligase activity. Degradation of p53 by RBBP6 may compromise p53-mediated apoptosis in breast cancer. This study is intended to investigate, the potential applications of RNA interference (RNAi) to block RBBP6 expression, as well as its subsequent effect on cell growth and apoptosis. Our studies indicate that the knockdown of RBBP6 by siRNA modulates p53 gene expression involved in cell death pathways and apoptosis, showing statistically significant gene expression differences. RBBP6 siRNA significantly reduced cell growth compared to the control samples and inhibition of cellular proliferation was observed between 24 and 48h, as shown in the data obtained by real time cell analysis using the xCELLigence system. These results were further confirmed by flow cytometer which showed some apoptotic activity. About 20.7% increase in apoptosis was observed in cells co-treated with RBBP6 siRNA and camptothecin when compared to camptothecin-only whereas in siRBBP6 and staurosporine treated cells there was only an 8.8% increase in apoptosis. These findings suggest that silencing RBBP6 may be a novel strategy to promote camptothecin-induced apoptosis in breast cancer cells.
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Affiliation(s)
- Pontsho Moela
- School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Mpho M S Choene
- School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa
| | - Lesetja R Motadi
- School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa.
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Thafeni MA, Sayed Y, Motadi LR. Euphorbia mauritanica and Kedrostis hirtella extracts can induce anti-proliferative activities in lung cancer cells. Mol Biol Rep 2012; 39:10785-94. [PMID: 23086267 DOI: 10.1007/s11033-012-1972-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 10/01/2012] [Indexed: 11/28/2022]
Abstract
Cancer is a public health problem in the world accounting for most of the deaths. Currently, common treatment of cancer such as chemotherapy works by killing fast-growing cancer cells. Unfortunately, chemotherapy cannot tell the difference between cancer cells and fast-growing healthy cells, including red and white blood cells. As a result, one of the most serious potential side effects of some types of chemotherapy is a low white blood cell count that makes it unreliable (Parkin et al. [34]; Pauk et al. [3]). Even though intense research has been going on in recent years, successful therapeutic targets against this disease have been elusive. In this study, we evaluate the anti-proliferative activity of Euphorbia mauritanica and Kedrostis hirtella in lung cancer. In our assessment it was observed that E. mauritanica and K. hirtella were able to induce cell death at 5 μg/ml in A549 cells over 22 h and at 10 μg/ml over 24 h in the Lqr1 cell line. Molecular analysis of DNA fragmentation and Annexin V were used to examine the type of cell death induced by E. mauritanica and K. hirtella extracts. These results showed an increase in necrotic and apoptotic characteristics with both nuclear DNA fragmentation and smear. Therefore, these results suggest that E. mauritanica and K. hirtella may play a role in inducing cell death in lung cancer cells. However, further studies need to be conducted to ascertain these results.
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Affiliation(s)
- Makhosazana A Thafeni
- Apoptosis and Cancer Genetic Laboratory, School of Molecular Biology, University of the Witwatersrand, Johannesburg, South Africa
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Fieber LA, Greer JB, Guo F, Crawford DC, Rein KS. GENE EXPRESSION PROFILING OF HUMAN LIVER CARCINOMA (HepG2) CELLS EXPOSED TO THE MARINE TOXIN OKADAIC ACID. TOXICOLOGICAL AND ENVIRONMENTAL CHEMISTRY 2012; 24:1805-1821. [PMID: 23172983 PMCID: PMC3500632 DOI: 10.1080/02772248.2012.730199] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The marine toxin, okadaic acid (OA) is produced by dinoflagellates of the genera Prorocentrum and Dinophysis and is the causative agent of the syndrome known as diarrheic shellfish poisoning (DSP). In addition, OA acts as both a tumor promoter, attributed to OA-induced inhibition of protein phosphatases as well as an inducer of apoptosis. To better understand the potentially divergent toxicological profile of OA, the concentration dependent cytotoxicity and alterations in gene expression on the human liver tumor cell line HepG2 upon OA exposure were determined using RNA microarrays, DNA fragmentation, and cell proliferation assays as well as determinations of cell detachment and cell death in different concentrations of OA. mRNA expression was quantified for approximately 15,000 genes. Cell attachment and proliferation were both negatively correlated with OA concentration. Detached cells displayed necrotic DNA signatures but apoptosis also was broadly observed. Data suggest that OA has a concentration dependent effect on cell cycle, which might explain the divergent effects that at low concentration OA stimulates genes involved in the cell cycle and at high concentrations it stimulates apoptosis.
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Affiliation(s)
- Lynne A. Fieber
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Justin B. Greer
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Fujiang Guo
- Department of Chemistry and Biochemistry, 11200 SW 8 St, Florida International University, Miami, FL, USA33199
| | - Douglas C. Crawford
- Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL, USA 33149
| | - Kathleen S. Rein
- Department of Chemistry and Biochemistry, 11200 SW 8 St, Florida International University, Miami, FL, USA33199
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Mbita Z, Meyer M, Skepu A, Hosie M, Rees J, Dlamini Z. De-regulation of the RBBP6 isoform 3/DWNN in human cancers. Mol Cell Biochem 2011; 362:249-62. [PMID: 22139301 DOI: 10.1007/s11010-011-1150-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 11/03/2011] [Indexed: 01/30/2023]
Abstract
Retinoblastoma binding protein 6 (RBBP6) is a nuclear protein, previously implicated in the regulation of cell cycle and apoptosis. The human RBBP6 gene codes for three protein isoforms and isoform 3 consists of the domain with no name domain only whilst the other two isoforms, 1 and 2 comprise of additional zinc, RING, retinoblastoma and p53 binding domains. In this study, the localization of RBBP6 using RBBP6 variant 3 mRNA-specific probe was performed to investigate the expression levels of the gene in different tumours and find a link between RBBP6 and human carcinogenesis. Using FISH, real-time PCR and Western blotting analysis our results show that RBBP6 isoform 3 is down-regulated in human cancers. RBBP6 isoform 3 knock-down resulted in reduced G2/M cell cycle arrest whilst its over-expression resulted in increased G2/M cell cycle arrest using propidium iodide DNA staining. The results further demonstrate that the RBBP6 isoform 3 may be the cell cycle regulator and involved in mitotic apoptosis not the isoform 1 as previously reported for mice. In conclusion, these findings suggest that RBBP6 isoform 3 is a cell cycle regulator and may be de-regulated in carcinogenesis.
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Affiliation(s)
- Zukile Mbita
- College of Agriculture and Environmental Science, University of South Africa, Florida Campus, Johannesburg, South Africa
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