Silencing RBBP6 (Retinoblastoma Binding Protein 6) sensitises breast cancer cells MCF7 to staurosporine and camptothecin-induced cell death.
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.
School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa.
Pontsho
P
Moela
School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa.
Mpho M S
MM
Choene
School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg 2050, South Africa. Electronic address: Lesetja.motadi@wits.ac.za.
Lesetja R
LR
Motadi
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics; D002166:Camptothecin / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D048708:Cell Growth Processes / Q000187:drug effects / Q000235:genetics; D003131:Combined Modality Therapy; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D005260:Female; D020868:Gene Silencing; D006801:Humans; D061986:MCF-7 Cells; D034741:RNA, Small Interfering / Q000235:genetics; D019311:Staurosporine / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases
D000972:Antineoplastic Agents, Phytogenic; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; C098584:RBBP6 protein, human; D044767:Ubiquitin-Protein Ligases; D019311:Staurosporine; D002166:Camptothecin
Apoptosis; Camptothecin; RNA interference; Retinoblastoma Binding Protein 6; Staurosporine