Drug library screening identifies histone deacetylase inhibition as a novel therapeutic strategy for choriocarcinoma

Background: Choriocarcinoma is a rare and aggressive gynecological malignancy. The standard treatment is systemic chemotherapy as choriocarcinoma exhibits high chemosensitivity. However, refractory choriocarcinoma exhibits chemoresistance; thus, the prognosis remains very poor. This study aimed to identify novel therapeutic agents for choriocarcinoma by utilizing a drug repositioning strategy. Methods: Three choriocarcinoma cell lines (JAR, JEG-3, and BeWo) and a human extravillous trophoblast cell line (HTR-8/SVneo) were used for the analyses. The growth inhibitory effects of 1,271 FDA-approved compounds were evaluated in vitro screening assays and selected drugs were tested in tumor-bearing mice. Functional analyses of drug effects were performed based on RNA sequencing. Results: Muti-step screening identified vorinostat, camptothecin (S, +), topotecan, proscillaridin A, and digoxin as exhibiting an anti-cancer effect in choriocarcinoma cells. Vorinostat, a histone deacetylase inhibitor, was selected as a promising candidate for validation and the IC50 values for choriocarcinoma cells were approximately 1 μM. RNA sequencing and subsequent pathway analysis revealed that the ferroptosis pathway was likely implicated, and key ferroptosis-related genes (i.e., GPX4, NRF2, and SLC3A2) were downregulated following vorinostat treatment. Furthermore, vorinostat repressed tumor growth and downregulated the expression of GPX4 and NRF2 in JAR cell-bearing mice model. Conclusion: Vorinostat, a clinically approved drug for the treatment of advanced primary cutaneous T-cell lymphoma, showed a remarkable anticancer effect both in vitro and in vivo by regulating the expression of ferroptosis-related genes. Therefore, vorinostat may be an effective therapeutic candidate for patients with choriocarcinoma.