Abstract 4134: Developmental pluripotency associated 4: A novel putative predictor for prognosis of aggressive prolactin secreting tumors in the pituitary

Prolactin-secreting pituitary tumors (prolactinomas) are the most common pituitary tumors in humans. Majority of prolactinomas are adenomas and benign and slow growing, but in some cases, they are locally aggressive and invasive. In a rat animal model we found that fetal alcohol exposed female rats develop aggressive prolactinomas following estrogen administration. Several recent evidence suggest that human cancer is a stem cells disease because many embryonic stem cell markers such as OCT4, SOX2, Nanog, and Klf4 are reexpressed in malignant tumor. The developmental pluripotency associated 4 (DPPA4) gene has an important role in self-renewal and pluripotency in embryonic stem cells. It is re-expressed in several malignant tumors and is identified as a new pluripotency-related oncogene. We studied wither DPPA4 expresses and function in aggressive prolactinomas induced by fetal alcohol exposures. Pregnant Fischer 344 rats were fed between gestational days 7 and 21 with a liquid diet containing alcohol, pair-fed with isocaloric liquid diet, or fed ad libitum with rat chow. At 60 days of age, female offspring rats were ovarictomized and received a subcutaneous estradiol implant. These rats were sacrificed at 3 months after the estradiol implants. Pituitary tumors were collected and pituitary tumorspheres were prepared and maintained in cultures. Alcohol-fed pituitary tumorspheres, but not control-fed pituitary tumorspheres, expressed DPPA4 and a panel of genes related to multipotency (OCT4, NANOG, KLF4, and CD133) and showed increased invasiveness and marked growth in cultures and in mice xenografts. The RNA sequence analyses identified selective expression of DPPA4 in the pituitary of fetal alcohol-exposed rats but not in control rats. Ingenuity pathway analysis of the RNA sequence data showed interrelationship of DPPA4 expression with the overexpression of pluropotent factors SOX2 and NANOG and several growth promoting molecules such as Wnt5a, TWIST1 and CTNNB1 and ESR1. Real-time PCR and western blot analysis confirmed overexpression of DPPA4 and its network growth promoting factors in pituitary tumors and in pituitary tumorspheres of fetal alcohol exposed rats. Deletion of DPPA4 gene from pituitary tumorspheres using a CRIPR Cas9 technique reduced the tumor cell ability to proliferate, migrate and form colony in soft agar. These data suggest that DPP4 is selectively expressed in aggressive prolactin-secreting tumors in the pituitary and controls the growth and migration of these tumors. (This work is supported by a National Institute of Health grant R01 AA11591). Citation Format: Shaima Jabbar, William Belden, Omkaram Gangisetty, Dipak K. Sarkar. Developmental pluripotency associated 4: A novel putative predictor for prognosis of aggressive prolactin secreting tumors in the pituitary [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4134. doi:10.1158/1538-7445.AM2017-4134