Functional studies of the RBBP6 (retinoblastoma binding protein 6) gene and its related genes in breast and cervical cancer : a promising diagnostic and management assay for cancer progression

A thesis submitted to the Faculty of Science under the school of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Doctor of Philosophy. Gauteng, Johannesburg, 2016.Overexpression of RBBP6 in cancers of the colon, lung and oesophagus makes it a potential target in anticancer therapy. This is especially important because it associates with the tumour suppressor gene p53, inactivation of which has been linked to over 50% of all cancer types. Cancer is an enormous burden of a disease globally. Today, more people die from cancer than HIV/AIDS, tuberculosis and malaria combined. And in females, breast and cervical malignancies remain the most common types. Currently, cervical cancer is the most diagnosed gynaecological cancer type, whose mortality rate is the highest in developing countries due to the asymptomatic nature of the disease coupled with inadequate cancer control tools and facilities. Breast cancer incidence rate has increased beyond that of lung cancer, making it the most common malignancy among women.GR201

Apoptotic Molecular Advances in Breast Cancer Management

Breast cancer is the most common cancer type amongst women, accounting for most female cancer deaths second to cervical cancer worldwide. It is, therefore, highly crucial to understand the molecular biology and explore other pathways involved in carcinogenesis in order to select appropriate treatment not only for breast cancer but for other cancers as well. Cancer progression is favoured by DNA damage and in most cases a consequent disruption of the apoptotic pathway, thus leading to uncontrolled cell proliferation. Therefore, current therapeutic strategies aim at targeting the apoptotic pathways in order to combat cancer. In this manuscript, we discuss the ways in which evasion of apoptosis during carcinogenesis occurs and the types of current therapeutic strategies as well as promising future approaches against breast cancer

Silencing RBBP6 (Retinoblastoma Binding Protein 6) sensitizes breast cancer cells to staurosporine and camptothecin-induced cell death

A dissertation submitted to the Faculty of Science, University of Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science. Gauteng, Johannesburg, 2013.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 (Ntwasa, 2008). 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. To achieve these methodologies, the following techniques were used: RT-PCR, western blotting, xCELLigence system and flow cytometry. Our studies indicate that the knockdown of RBBP6 expression by siRNA modulates p53 gene involved in cell death pathways and apoptosis, showing statistically significant gene expression differences. RBBP6siRNA significantly reduced cell index (CI) compared to the control samples and we observed an inhibition of cellular proliferation in the interval of between 24 and 48 h, as shown in the data obtained by dynamic evaluation using the xCELLigence System. These results were further confirmed by flow cytometry 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 there was only 8.8% increase in apoptosis. These findings suggest that silencing RBBP6 may be a novel strategy to promote staurosporine- and camptothecin-induced apoptosis in breast cancer cells. Keywords: Retinoblastoma Binding Protein 6, staurosporine, camptotheci

Investigating the effects of RBBP6 gene expression on telomerase activity in cervical cancer cells

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.South Africa Medical Research Councilhttp://www.dovepress.com/cancer-management-and-research-journalpm2021Biochemistr

Advancing global equity in cancer genomics – challenges and opportunities in Sub-Saharan Africa

Developments in genomics in the last decade has improved our understanding of the role of genetics in health and disease. One area where the impact of genomics is very noticeable is in oncology, specifically in terms of diagnosis and elucidating genetic predisposition to rare and common cancers. Sub-Saharan Africa (SSA) stands to benefit from cancer genomics, given recent spikes in the incidence of various types of cancers in the region. This mini review presents, from a health and science equity perspective, how genomics could shape cancer research and clinical care in SSA. We highlight some pan-African genomics and cancer initiatives that are facilitating cancer genomics research in SSA. We conclude with recommendations on how the ideals of equity may be advanced in cancer genomics initiatives in SSA.The Sickle Africa Data Coordinating Centre, the South Africa Medical Research Council and the National Research Foundation.http://www.current-opinion.com/journals/current-opinion-in-genetics-and-developmenthj2022ImmunologyOral Pathology and Oral Biolog

Antibacterial and cytotoxic activities of undescribed cassiaric acid and other constituents from Cassia arereh stem barks

Please read abstract in the article.The South African Medical Research Council Self-Initiated Research (SAMRC) and the National Research Foundation Thuthuka.https://www.tandfonline.com/loi/gnpl20hj2023BiochemistryChemistryGeneticsMicrobiology and Plant Patholog

RBBP6 expressional effects on cell proliferation and apoptosis in breast cancer cell lines with distinct p53 statuses

INTRODUCTION : Breast cancer is the most common malignancy amongst women and has a higher incidence rate than lung cancer. Its tumor progression partially results from inactivation of p53 which is caused by overexpression of ubiquitous regulatory proteins possessing p53-binding domain. RBBP6 is regarded as one of the ubiquitous proteins because of its RING finger-like domain which enables it to possess E3 ligase activity. Thus, it has become a potential target in cancer treatment as it is highly expressed in various malignancies including cancer. However, it is not clearly defined whether the effect of RBBP6 on cell growth and apoptosis is cell linedependent, more especially in breast cancer cell lines that have distinct p53 expression profiles. This study aims at evaluating the effects of RBBP6 on cell growth and apoptosis in breast cancer cell lines with different p53 expressions. METHODS : Following the analysis at mRNA and protein levels in breast cancer tissue, RBBP6 expression was successfully manipulated using gene silencing and protein overexpression techniques in MCF-7 and MDA-MB-231 cell lines. The cells were co-treated with siRBBP6 and anticancer agents following apoptosis detection, which was confirmed by caspase 3/7 activity and quantification of apoptotic genes. RESULTS : RBBP6 was overexpressed in breast cancer tissues that were classified as stages 3 and 4, while in stage 1, its expression was much lower. The MCF-7 cell line which expresses wild-type p53 was more sensitive to apoptosis induction than MDA-MB-231 which is a mutant p53-expressing cell line. These data suggest that RBBP6 silencing triggers significant levels of intrinsic apoptosis, and its overexpression appears to promote cell proliferation in wild-type p53-expressing MCF-7 cell line as opposed to MDA-MB-231 cells. CONCLUSION : The effect of RBBP6 on cell proliferation and apoptosis induction in breast cancer seems to be cell line-dependent based on p53 status.The South African Medical Research Council (MRC)https://www.dovepress.com/cancer-management-and-research-journalam2019Genetic