Blockage of cytosolic phospholipase A2 alpha sensitizes aggressive breast cancer to doxorubicin through suppressing ERK and mTOR kinases

Abstract

Advanced breast cancer is resistant to chemotherapy and its underlying mechanisms are not fully explored. In this work, we identified cytosolic phospholipase A2 alpha (cPLA2α) as a novel target to overcome chemoresistance in breast cancer. We demonstrated the increased transcriptional and translational expression of cPLA2α in breast cancer cells to acute and chronic exposure to doxorubicin. cPLA2α upregulation is also observed in breast cancer patients in response to chemotherapy. Inhibition of cPLA2α using two pharmacological inhibitors significantly enhances doxorubicin's effects to almost complete suppression in breast cancer cell growth, survival and migration. Similarly, depletion of cPLA2α significantly sensitizes breast cancer cells to doxorubicin treatment. We further found that cPLA2α inhibition led to decreased phosphorylation of ERK, mTOR, S6 and 4EBP1, suggesting the suppression of ERK and mTOR signaling pathways. These findings indicate the positive roles of cPLA2α in breast cancer cell growth, survival, migration and response to chemotherapy. Our work also highlights the therapeutic value of blocking cPLA2α to overcome chemoresistance in breast cancer.

Keywords: Breast cancer; Doxorubicin; ERK; cPLA2α; mTOR.