Effects of a ribosome inactivating plant protein (riproximin) on transcriptomic profile of apoptosis pathway genes in breast cancer cells

Background: Treatment options for breast cancer are limited and the available possibilities are largely palliative in nature. In this context, searching for more effective therapeutic compounds is inevitable. Riproximin, a plant derived ribosomal inactivating protein, is one such kind of anticancer compound and has shown substantial anticancer effects while altering the major components of different molecular pathways including cell cycle, autophagy, cell stress and apoptosis. The purpose of this study was to investigate the effects of riproximin exposure on expressional levels of genes associated with apoptotic pathway in breast cancer cell lines. Methods: In first phase, breast cancer cell lines (MDA-MB-231 and MCF-7) were exposed to riproximin and toxic effects were identified by MTT dye reduction assay. Afterwards, the cell lines were exposed to riproximin in a separate experiment and expressional modulations of multiple genes were evaluated via real-time PCRs. Fold changes in this study were calculated by Livak method (2∆∆Ct) while using untreated cells as controls. Results: Proliferation (MTT) assay showed that riproximin induced promising cytotoxic effects in breast cancer cell lines. MCF-7 cells were more responsive towards riproximin exposure as compared to MDA-MB-231 cells. Expressional assessment of the selected genes confirmed the potential of riproximin to alter the levels in breast cancer cells. Specifically, in response to riproximin exposure, three most effectively induced genes in MDA-MB-231 cells were BIK (83fold), TNFSF9 (59fold) and NFKB1 (20fold). In MCF-7 cells, three most up-regulated genes after riproximin treatment were TNF (129fold), LTA (58fold) and TNFSF9 (17fold). Conclusion: Riproximin bears significant cytotoxic potential against breast cancer cell lines. Expressional modulations in multiple apoptotic related genes are imposed by riproximin in the breast cancer cells. Further in vitro and in vivo studies are required to support the evaluation of riproximin in clinical settings against breast cancer cells, while targeting the apoptotic routes for cancer treatments.