Probing the effects of retinoblastoma Binding Protein 6 (RBBP6) knockdown on the sensitivity of cisplatin in cervical cancer cells.
Moela, P.1*, Mehta, H.1, Ambele, M. A.2,3, and Mokgautsi, N.1
1 Department of Biochemistry, Genetics and Microbiology, University of Pretoria, South Africa
2 Department of Immunology and SAMRC Extramural Unit for Stem Cell Research and Therapy, University of Pretoria, Pretoria, South Africa
3 Department of Oral and Maxillofacial Pathology, University of Pretoria, Pretoria 0001, South Africa
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. Retinoblastoma binding protein 6 (RBBP6) is a potential biomarker associated with cell proliferation and is up-regulated in cervical cancer sites, exhibiting apoptosis and dysregulated p53 expression and has been demonstrated to sensitize cancer cells to radiation and certain chemotherapeutic agents by regulating the Bcl-2 gene, thus suggesting a cross-talk 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. Cells co-treated with cisplatin and siRBBP6 were subsequently analyzed for apoptosis induction and real-time growth monitoring. Cancer cells in the co-treatment group showed a reduction in apoptosis compared to the cisplatin-treated group. Moreover, the cells had a reduced growth rate in the RBBP6-knockdown group 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. Findings from this study suggest that RBBP6 expression promotes cisplatin sensitivity in HeLa cells through Bcl-2 downregulation.
Keywords: RBBP6, BCl-2, cervical cancer, cisplatin, drug resistance
