Abstract 3595: Effects of fetal alcohol exposure on tumor development and gene expression in rats.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Fetal alcohol exposure increases susceptibility to carcinogen induced mammary tumors in adult rats. These animals exhibit hyperproliferative mammary glands pre-pubertally, suggesting that early changes are taking place in the mammary gland. To determine the molecular mechanisms that underlie these effects, pregnant Sprague Dawley rats were fed a liquid diet containing 6.7% ethanol, pair-fed an isocaloric liquid diet, or fed rat chow ad libitum from days 11 to 21 of gestation. Pups were cross-fostered to ad libitum-fed control dams at birth. At postnatal day 50, offspring were injected with NMU to induce mammary tumors and tissues were collected at 16 weeks post-injection, the time-point when approximately half of all animals exhibited tumors in our previous study. Significantly more tumors were observed in the fetal alcohol group compared to control groups. Histological analysis indicated that fetal alcohol exposed rats developed more adenocarcinomas. Interestingly, mammary tissue from these animals exhibited more adenosis compared to controls. Since we have previously observed changes in the estradiol/estrogen receptor (ER) system and a recent study found that epithelial to mesenchymal transition (EMT) genes are altered in the rat fetal alcohol NMU model, a custom PCR array was designed to examine expression of genes involved in EMT, estradiol/ER signaling, and tumorigenesis in tumor samples and mammary tissue collected from contralateral tumor-free glands. Mammary glands from fetal alcohol animals had increased expression of EMT genes compared to pair-fed controls. Snail and Twist, two genes whose increased expression is considered the hallmark of EMT, exhibited the greatest changes. Previously, we found that mammary tumors collected at 23 weeks post-NMU injection were more ER negative in fetal alcohol animals. Therefore, we were interested in determining if a similar change was evident at 16 weeks post-injection. Immunohistochemical (IHC) analysis indicated that at this earlier time-point, mammary tumors from the fetal alcohol group were not more ER negative compared to controls. To determine if the ER is functional, IHC analysis was performed to determine the expression of progesterone receptor (PR), a downstream target of ER. The majority of tumors from each treatment group were PR negative. To complete the receptor status profile, IHC was also performed for HER2. The majority of all tumors across the three treatment groups were HER2 negative. These data indicate that fetal alcohol exposure alters expression of several genes in the mammary gland, which may be involved in the molecular mechanisms underlying the increased risk in mammary tumorigenesis. Citation Format: Catina Crismale-Gann, Tiffany A. Polanco, Hillary Stires, Wendie S. Cohick. Effects of fetal alcohol exposure on tumor development and gene expression in rats. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3595. doi:10.1158/1538-7445.AM2013-3595