Abstract
Background: Epidemiologic and pre-clinical studies have shown that marine n-3 polyunsaturated fatty acids (n-3 PUFAs) elicit promising chemoprevention against breast cancer. Previous studies found that docosahexaenoic acid monoglyceride (MAG-DHA) does not required pancreatic lipase to be absorbed, unlike DHA-triglyceride which needs to be hydrolyzed by sn-1,3’ specific gastric and (colipase-dependent) pancreatic lipases as free fatty acids and monoglycerol prior to intestinal absorption. Therefore, this property confers increased absorption, and thus a better bioavailability when compared with other formulations such as DHA-free fatty acid, DHA-triglycerol (TAG-DHA), or DHA-ethyl ester (EE-DHA). However, the anti-cancer actions of n-3 PUFA monoglyceride on breast cancer remain to be assessed.Methods: SKBR3 and E0771 cells were exposed in vitro to MAG-DHA. Cell viability (by MTT), malondialdehyde (MDA) levels, cell apoptosis and autophagy (by western blot), Beclin1 knockout (by siRNA) was examined. Transmission electron microscopy (TEM) was used for analyzing cell apoptosis and autophagy in vivo breast cancer exnografts. Results: In this study, we showed that docosahexaenoic acid monoglyceride (MAG-DHA) caused oxidative stress as evidenced by MDA accumulation, which triggered endoplasmic reticulum (ER) stress and subsequently induced apoptosis in E0771 and SKBR3 breast cancer cells. In particular, MAG-DHA-induced apoptosis is associated with the activation of the PERK-eIF2α pathway and caspase-12. MAG-DHA treatment also strongly suppressed the growth of E0771 murine breast cancer xenografts, by ER-stress-induced cell apoptosis. In addition, we found that MAG-DHA-induced ER stress concomitantly triggered autophagy in these cancer cells, and the induction of autophagy suppressed its ability to induce apoptotic cell death. Conclusions: Together, our data suggested that MAG-DHA combined with autophagy inhibitors may be a useful therapeutic strategy in treating breast cancer.
Loss of Stearoyl‐CoA Desaturase activity increases ER stress and PKCζ mediated inhibition of Akt in response to saturated fatty acids in breast cancer cells.
