Maternal high fat diet has been shown to increase mammary cancer risk among female offspring. We investigated here if the increase is seen across multiple generations. For that purpose, pregnant C57BL/6NTac dams (F0) were fed either a control (CON, 6% corn oil) or an isocaloric high n-6 polyunsaturated fat (HF) diet (18% corn oil) between gestation days 8 and 21. Offspring in subsequent generations (F1-F3) were not exposed to any further dietary modifications, and kept on CON diet. Mammary tumors were initiated by priming the mammary glands with 15 mg medroxyprogesterone (MPA) at week 6, followed by a 1 mg dose of 7,12-dimethylbetz(a)anthracene (DMBA) given on weeks 7-9 for a total of 3 doses. Animals were monitored for 20 weeks after the final dose of DMBA for tumors. Both F1 and F3 generation female HF offspring exhibited a significantly higher mammary tumor incidence and tumor burden than the control offspring. In F3 generation, the increase was seen from week 12 of tumor monitoring until the end of the study. The increase in risk was preceded by a higher number of terminal end buds in the F1 and F3 generation mammary glands. Malondialdehyde (MDA) adduct levels were found to be significantly elevated in the HF group of F3 offspring, suggesting that the increased mammary cancer risk in this generation was attributed to oxidative stress. Western blot analysis of mammary glands identified significantly elevated Keap1 (a repressor of the antioxidant response) and PERK levels in HF F3 offspring; and elevated levels of Beclin-1 and p62 in both F1 and F3 generations compared with CON offspring, corroborating with the idea that oxidative stress was the culprit. miRNA analysis of F3 mammary glands showed decreased expression of mir-324-5p, mir-136 and mir-378 that target Keap1 and p62, potentially explaining the increase in Keap1 and p62 levels. Our results suggest that oxidative stress and antioxidant response plays a role in explaining transgenerational increase in mammary cancer risk among offspring exposed to high fat diet through F0 dams.

Citation Format: Nguyen M. Nguyen, Fabia O. Andrade, Sonia DeAssis, Idalia Cruz, Carlos Benitez, Roger Godschalk, Leena Hilakivi-Clarke. Transgenerational inheritance of increased mammary cancer risk in the offspring of high fat diet fed dams: Changes in oxidative stress pathways. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 901.