Abstract 7579: Dual inhibition of enhancer of zeste homolog 1 2 induces pyroptosis, modulates oncogenic signaling pathways & sensitizes hepatocellular carcinoma to valemetostat & docetaxel treatments

Abstract HCC is a global health concern, with chemotherapy resistance and patient recurrence posing significant challenges to liver cancer treatment. EZH2 is a crucial part of the polycomb repressive complex 2 (PRC2). It, along with its homolog EZH1, is a focus for cancer therapeutic targets. Dysregulation of EZH1/2 can cause cancer development due to significant changes in geneexpression. The current study aims to investigate the interaction between EZH1/2 and oncogenic signals responsible for HCC progression and pyroptosis induction. Two cell lines, HepG2 and SK-Hep1, were subjected to two FDA-approved drugs, Valemetostat (Val) and Docetaxel (Doc), to determine the impact of EZH1/2 on tumorigenicity and drug resistance. The WST-1 assay was utilized to gauge cell proliferation. The results indisputablydemonstrated a synergistic effect of the drugs after 48 h of treatment. The inhibition of viability was attributed to apoptosis induction in both tested cell lines, and the maximum effect was observed in the combined treatment as compared to either the control or each drug alone. Furthermore, our datashowed activation of caspase-3, upregulation of BAX, indicating apoptotic induction, and downregulation of Bcl-2, Bcl-XL, AKT, S6k, oncogenic β-catenin, and Stat3 protein expression levels, suggesting a modulation of oncogenic signaling pathways at the protein level. After 24 h of Val/Doc treatment, pyroptosis was observed, characterized by cell swelling and bubbles on themembrane and a significant release of lactate dehydrogenase, indicating pyroptotic cell cytotoxicity. The antitumor effects and pyroptosis were enhanced by using a dual inhibitor, UNC1999, for EZH1/2, resulting in a marked increase in the sensitivity of tested cells to the Val/Doc treatment invitro. The present study unequivocally demonstrated that dual inhibition of EZH1/2 acts as a potent sensitizer of HCC cells to Val/Doc treatment, which might be a promising therapeutic approach for inducing cellular pyroptosis in HCC cell lines. Citation Format: Asmaa Elkhder Harira, Adham Maher, Ahmed Sultan. Dual inhibition of enhancer of zeste homolog 1 2 induces pyroptosis, modulates oncogenic signaling pathways Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7579.