Targeting mirna-protein regulatory networks to enhance chemotherapy response in BRCA1-mutated TNBCs

Breast cancer is the second most common cancer and the leading cause of cancer associated deaths in women worldwide. Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. BRCA1-mutated TNBC patients generally respond well to DNA cross-linking agents like Cisplatin. However, most of the patients acquire resistance and eventually die. Therefore, there is a dire need of developing promising approaches to enhance chemo-response, hence, extending the survival of TNBC patients. MicroRNAs (miRNAs) play active role in controlling proliferation, apoptosis, invasion and drug resistance in cancer. However, the role of miRNA-protein interactions as a regulatory network in determining chemotherapy response of TNBCs has not been elucidated yet. Thus, we aimed to delineate miRNAs and miRNA-protein regulatory networks controlling chemotherapy resistance/response in BRCA1–mutated TNBCs. We firstly confirmed that BRCA1-mutated breast cancer cells are more sensitive to Cisplatin as compared to BRCA1-competent cells. Afterwards, developing acquired chemotherapy resistant cell line model and using next generation sequencing technology (both miR-Seq and RNA-Seq), we have unravelled that p53 signalling is the upstream regulator of Cisplatin resistance. Moreover, with the use of Ingenuity Pathway Anlaysis (IPA) which uses omics data from a variety of experimental platforms, we analyzed, combined and modelled miRNA-mRNA interactions regulating Cisplatin resistance for the first time in a network manner. Interestingly, we identifed several network motifs e.g. coherent and incoherent feedforward loops centered around p53 protein which need further experimental validations. Again for the first time, this study has reported the re-sensitization effect of miR-455 family on Cisplatin resistance in breast cancer. Overall, findings of this study might be used as an alternative strategy for treatment of BRCA1-mutated TNBCs by modulating miRNAs and their targets to re-sensitize Cisplatin resistant tumors.