Although Omega 3-polyunsatuarated fatty acids (Omega 3-PUFAs) induce cytotoxicity in several cancer cell lines, the exact mechanisms are not identified yet. In this study, we showed that autophagy is involved in the Omega 3-PUFAs-induced cytotoxicity in cancer cells. Autophagy is characterized by the sequestration of cytoplasmic material within autophagosomes for bulk degradation by lysosomes. We found that docosahexaenoic acid (DHA), an Omega 3-PUFA, induced not only apoptosis but also autophagy in cancer cells. Autophagy was detected after DHA exposure as indicated by induction of LC3 expression, and formation of autophagic vacuolization. We observed that the DHA-induced autophagy was accompanied by loss of p53. Inhibition of p53 by Pifithrin-α or microRNA-p53 significantly increased the DHA-induced autophagy, suggesting that the DHA-induced autophagy is mediated by downregulation of p53. Further experiments showed that the mechanism of the DHA-induced autophagy associated with p53 attenuation, involved an increase in the active form of AMPK which attenuated the mTOR activity as revealed by p27 sequestration. In addition, compelling evidence for the interplay between autophagy and apoptotic cell death induced by DHA is supported by the findings that autophagy inhibition partially decreased the DHA-induced apoptotic cell death and further autophagy induction by p53 inhibitor enhanced apoptosis in response to treatment with DHA in cancer cells. Our results demonstrate that autophagy may be related to the DHA-induced cytotoxicity in cancer cells. [This work was supported by basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (E00026 and R13-2007-020-01000-0].

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2867. doi:10.1158/1538-7445.AM2011-2867