Abstract 2743: Synergistic efficacy of telomerase-specific oncolytic adenoviral therapy and histone deacetylase inhibition in human hepatocellular carcinoma
Authors: Lin Zhong-Zhe , Hu Mickey C-T. , Hsu Chiun , Wu Yao-Ming , Lu Yen-Shen , Ho Ja-An Annie , Yeh Shiou-Hwei , Chen Pei-Jer , Cheng Ann-Lii 
Published: April 2023

Abstract
Background: The telomerase-specific oncolytic adenovirus Telomelysin along with the histone deacetylase inhibitor AR42 have both demonstrated anticancer effects in preclinical models of human hepatocellular carcinoma (HCC). However, the clinical development of Telomelysin may be hindered by human antiviral immunity and tumor resistance. Combining oncolytic and epigenetic therapies has been reported to be a viable approach for treating various cancers. We investigated the potential synergism of Telomelysin and AR42 and the relevant underlying mechanisms.
Method: HCC cell lines (PLC5 and Hep3B) were tested and median effect analysis was performed to estimate potential synergistic antiproliferative effects. Apoptosis was assessed by flow cytometry and Western blotting. The expression of coxsackievirus and adenovirus receptor (CAR) was measured through flow cytometry and immunofluorescence staining. Human telomerase reverse transcriptase (hTERT) mRNA expression was assessed by reverse transcription polymerase chain reaction. Western blotting was conducted to examine the activation of pivotal signaling pathways and the interferon (IFN) response. HCC cells constitutively overexpressing Akt were cloned for molecular mechanism verification. MK-2206 was used to inhibit the activation of Akt signaling. In vivo efficacy was determined through xenograft
models of human HCC.
Results: Telomelysin and AR42 exhibited synergistic antiproliferative effects in human HCC models in vitro and in vivo. Apoptosis induced by Telomelysin was significantly enhanced by AR42 in both PLC5 and Hep3B HCC cells. AR42 treatment unexpectedly attenuated the expression of the CAR and the mRNA levels of hTERT, which may be positively associated with the cytotoxicity of Telomelysin. Meanwhile, the cellular antiviral interferon response was not altered by AR42 treatment. Further, we found that Telomelysin enhanced Akt phosphorylation in HCC cells. AR42 reduced Telomelysin-induced phospho-Akt activation and enhanced Telomelysin-induced apoptosis. The correlation of Akt phosphorylation with drug-induced apoptosis was validated in HCC cells with upregulated or downregulated Akt signaling.
Conclusions: Combination therapy with Telomelysin and AR42 demonstrates synergistic anti-HCC efficacy. Clinical trials investigating this new combination regimen are warranted.
Keywords: Hepatocellular carcinoma, oncolytic adenovirus, Telomelysin, HDAC inhibitor, Akt
Citation Format: Zhong-Zhe Lin, Mickey C-T. Hu, Chiun Hsu, Yao-Ming Wu, Yen-Shen Lu, Ja-An Annie Ho, Shiou-Hwei Yeh, Pei-Jer Chen, Ann-Lii Cheng. Synergistic efficacy of telomerase-specific oncolytic adenoviral therapy and histone deacetylase inhibition in human hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2743.