PKCeta Promotes Stress-Induced Autophagy and Senescence in Breast Cancer Cells, Presenting a Target for Therapy

The emergence of chemoresistance in neoplastic cells is one of the major obstacles in cancer therapy. Autophagy was recently reported as one of the mechanisms that promote chemoresistance in cancer cells by protecting against apoptosis and driving senescence. Thus, understanding the role of autophagy and its underlying signaling pathways is crucial for the development of new therapeutic strategies to overcome chemoresistance. We have previously reported that PKC eta is a stress-induced kinase that confers resistance in breast cancer cells against chemotherapy by inducing senescence. Here, we show that PKC eta promotes autophagy induced by ER and oxidative stress and facilitates the transition from autophagy to senescence. We demonstrate that PKC eta knockdown reduces both the autophagic flux and markers of senescence. Additionally, using autophagy inhibitors such as chloroquine and 3-methyladenine, we show that PKC eta and autophagy are required for establishing senescence in MCF-7 in response to oxidative stress. Different drugs used in the clinic are known to induce autophagy and senescence in breast cancer cells. Our study proposes PKC eta as a target for therapeutic intervention, acting in synergy with autophagy-inducing drugs to overcome resistance and enhance cell death in breast cancer.