Abstract 1125: Developmental pluripotency associated 4 oncogene interacts with Wnt/β-catenin signaling and stem cells regulatory genes to control pituitary tumor cells invasiveness

Abstract

Abstract 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 have recently identified elevated expression of DPPA4 in aggressive pituitary tumors induced by estrogen in fetal alcohol exposed rats. In this study, we determined the role of DPPA4 in pituitary tumor growth and invasiveness by employing CRISPR/Cas9 knock-down of DPPA4 and conducting cell proliferation, in vitro soft agar anchorage-independent growth assays, and in vivo tumor formation assay using cell spheres from pituitary tumors of alcohol-fed and control-fed animals. Pituitary tumor cells of fetal alcohol-fed rats and control diet-fed rats were grown in ultra-low attachment plate to develop pituispheres. In vitro and in vivo studies showed pituispheres of alcohol-fed rats had higher cell proliferation rate, increased colony formation in soft agar, and higher tumor development in mice xenografts compared to those in pituispheres of alcohol-fed rats. Pituispheres of alcohol-fed rats also had increased mRNA levels of cell growth, cell stemness and EMT regulatory genes. CRISPR-Cas9 knockdown of DPPA4 in pituispheres reduced the tumor cell ability to proliferate, migrate and form colony in soft agar and grow in mice xenografts. Pituispheres of alcohol-fed rats also showed increased protein levels of Wnt/beta-catenin signaling molecules (Wnt 3, beta-catenin, LPR5, GSK3), stemness regulatory factors (KLF4, Sox2, Nanog) and EMT factors as compared to those in control-fed pituispheres. DPPA4 knockdown reduced the levels of Wnt signaling and stem cells regulatory proteins and EMT factors in alcohol-fed rat pituispheres. These data suggest that DPPA4 is expressed in aggressive pituitary tumors and regulates the growth and invasion of these tumors via activation of Wnt/beta-catenin signaling and stem cells regulatory genes. (This work is supported by a National Institute of Health grant R01 AA11591). Citation Format: Dipak K. Sarkar, Shaima Jabbar, Omkaram Gangisetty. Developmental pluripotency associated 4 oncogene interacts with Wnt/β-catenin signaling and stem cells regulatory genes to control pituitary tumor cells invasiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1125.