Overexpression of anti-apoptotic proteins belonging to the B cell lymphoma (Bcl)-2 family is observed in numerous cancer types and has been postulated to promote cancer cell survival and chemotherapy resistance. Bcl-extra large (xL)/myeloid cell leukemia sequence (Mcl)-1 was demonstrated to be expressed at relatively high levels in clinically aggressive basal-like cancers and inhibiting Bcl-xL overexpression could potentially provoke cell death. A molecule able to target Bcl-xL/Mcl-1, JY-1-106, is herein under investigation. It is also known that vitamin A-derived compounds exhibit antitumor activity in a variety of in vitro experimental models, promoting their effects via nuclear receptor isoforms including retinoic acid receptors (RARs). Pre-clinical observation highlighted that triple negative (estrogen receptor/progesterone receptor/human epidermal growth factor receptor)-breast cancer cells displayed resistance to retinoids due to the RARγ high expression profile. The present study used the triple-negative human breast cancer cell line, MDA-MB-231, to analyze the effects of the Bcl-xL/Mcl-1 synthetic inhibitor, JY-1-106, alone or in combination with retinoids on cell viability. The results revealed a synergistic effect in reducing cell viability primarily by using JY-1-106 with the selective RARγ antagonist SR11253, which induces massive autophagy and necrosis. Furthermore, the results highlighted that JY-1-106 alone is able to positively influence the gene expression profile of p53 and RARα, providing a therapeutic advantage in human triple-negative breast cancer treatment.
Keywords: Bcl-xL/Mcl-1 inhibitor; MDA-MB-231 breast cancer cells; RARγ antagonist; autophagy; retinoids.