Abstract 3987: Targeting nucleotide synthesizing enzyme dUTPase (DUT) represents a metabolic weakness and therapeutic opportunity in liver cancer

Abstract Hepatocellular carcinoma (HCC), the most common type of primary liver cancer, has an overall 5-year survival rate of around 20%, making it the third leading cause of cancer-related death worldwide. Upregulated nucleotide metabolism is frequently identified in HCC and represents a metabolic weakness of tumor cells. The enzyme dUTPase (DUT) catalyzes the synthesis of nucleotide precursor and prevents undesired uracil misincorporation into DNA, and thus plays an important role in the maintenance of DNA integrity and cell viability. Although common upregulation of DUT has been reported in cancers, its role in HCC remains largely unknown. In this study, we investigated the mechanism underlying DUT biology in HCC and tumor susceptibility to drug targeting dUTPase. Overexpression of DUT was found in 42% of HCC cases and significantly correlated with advanced stage tumors. CRISPR-Cas9 mediated knockout of DUT resulted in growth retardation, cell cycle arrest and a spontaneous induction of DNA damage in multiple HCC cell lines. A protective effect from oxidative stress was also demonstrated in both knockout and overexpression DUT assays. Metabolomics analysis showed altered DUT expression in HCC cells resulted in profound impact on pyrimidine and purine metabolism. In addition, levels of DUT protein strongly correlate with cellular level of dUTP and dTDP, which suggested its critical role in dNTP homeostasis. Interestingly, hepatic organoids overexpressing DUT showed drug resistance to tyrosine kinase inhibitor (TKI) Sorafenib. Both in vitro and in vivo assays confirmed that targeting dUTPase activity with TAS-114 synergized the effect of Sorafenib in suppressing HCC growth. In conclusion, our study showed that upregulated DUT conferred growth advantage to HCC cells by reducing uracil misincorporation and favoring nucleotide synthesis. Targeting DUT with its first-in-class inhibitor TAS-114 in combination with Sorafenib represents an effective treatment regime for HCC. Citation Format: Yue Liu, Mingjing Xu, Ho Lee Wan, Alissa M. Wong, Xiaofan Ding, Kelvin K. Ng, Nathalie Wong. Targeting nucleotide synthesizing enzyme dUTPase (DUT) represents a metabolic weakness and therapeutic opportunity in liver cancer. [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 3987.