Plac8 Confers The Chemoresistance Of Placental Site Trophoblastic Tumor And Choriocarcinoma To Etoposide In An Autophagy-Dependent Manner

Chemotherapy is commonly used to treat gestational trophoblastic neoplasia (GTN), but placental site trophoblastic tumor (PSTT) and a small proportion of choriocarcinoma demonstrate chemotherapy resistance, which becomes the major obstacle for the treatment. However, the underlying mechanism remains elusive. In the present study, we found that PLAC8 expression in PSTT tissues was higher than that in placental site intermediate trophoblast cells. In addition, PLAC8 was also highly expressed in human choriocarcinoma tissues compared with normal placental villi. Over-expression of PLAC8 inhibited p53 protein stability and induced the autophagic flux in HTR-8 and JAR cells. PLAC8-induced autophagic activity could be partially recovered by p53 re-expression. Further, PLAC8 over-expression conferred chemoresistance of trophoblast cells to etoposide, which can be effectively abrogated by autophagic inhibitors 3-methyladenine (3-MA) or chloroquine (CQ). In conclusion, over-expression of PLAC8 in PSTT and choriocarcinoma tissues may endow the trophoblast cells with enhanced chemoresistance via inducing autophagy activity. Therefore, PLAC8 may serve as a potential therapeutic target for the treatment of PSTT and choriocarcinoma. Citation Format: Xuan Feng, Huandi Yu, Xiang Tao, Yan Du, Jing Wu, Yinhua Yu, Congjian Xu, Hongbo Zhao. PLAC8 confers the chemoresistance of placental site trophoblastic tumor and choriocarcinoma to etoposide in an autophagy-dependent manner [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2988.