Autophagy inhibitor 3-methyladenine potentiates apoptosis induced by dietary tocotrienols in breast cancer cells

Introduction: Tocomin^® represents commercially available mixture of naturally occurring tocotrienols (T3s) and tocopherols extracted from palm oil/palm fruits that possess powerful antioxidant, anticancer, neuro/cardioprotective and cholesterol-lowering properties. Cellular autophagy represents a defense mechanism against oxidative stress and several anticancer compounds. Recently, we reported that T3s induce apoptosis and endoplasmic reticulum stress in breast cancer cells. Methodology: We studied the effects of Tocomin^® on MCF-7 and MDA-MB 231 breast cancer cells and non-tumor MCF-10A cells. Results: Tocomin^® inhibited cell proliferation and induced apoptosis in both MCF-7 and MDA-MB 231 breast cancer cell lines without affecting the viability of MCF-10A cells. We also showed that Tocomin^® negatively modulates phosphoinositide 3-kinase and mTOR pathways and induces cytoprotective autophagic response in triple negative MDA-MB 231 cells. Lastly, we demonstrate that autophagy inhibitor 3-methyladenine (3-MA) potentiated the apoptosis induced by Tocomin^® in MDA-MB 231 cells. Conclusion: Together, our data indicate anticancer effects of Tocomin^® in breast cancer cells, which is potentiated by the autophagy inhibitor 3-MA.