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Abstract Aberrant activation of the Wnt/β-catenin signaling pathway plays a crucial role in a wide range of human tumors including colorectal and liver cancer. The activated signaling causes nuclear accumulation of β-catenin, which leads to the elevated expression of target genes of TCF/LEF (T-cell factor/lymphoid enhancer factor) transcription factors through their interaction with nuclear β-catenin. Recent studies have identified a lot of genes induced by this pathway such as MYC, CCND1, AXIN2, and LGR5, and clarified their roles in tumorigenesis. However, the roles of the genes down-regulated by the pathway remain to be elucidated. Our previous study revealed that the histidine ammonia-lyase gene (HAL) encoding an enzyme involved in the catabolism of histidine was down-regulated by the signaling pathway in liver cancer. In addition, we identified a region that is involved in the Wnt-dependent regulation of HAL. To clarify the regulatory mechanism of HAL by the pathway, we searched for transcription factors that are associated with the regulatory region, and identified CEBPA and FOXA1, two liver-enriched transcription factors. It is of note that the expression of these factors was reduced by the TCF/β-catenin complex. Further investigation identified arginase 1 (ARG1) encoding an enzyme that catalyzes the hydrolysis of arginine as another target gene of CEBPA and FOXA1. Consistent with these data, inhibition of the Wnt signaling increased the expression of ARG1 as well as HAL in liver cancer cells. Furthermore, the up-regulation of HAL and ARG1 by the inhibition of this pathway decreased intracellular concentrations of histidine and arginine, suggesting that the Wnt signaling plays an important role in cellular metabolism through the regulation of the two transcription factors. These findings shed light on the role of the Wnt/β-catenin signaling pathway in the metabolism of amino acids in liver cancer cells. Citation Format: Saya Nakagawa, Kiyoshi Yamaguchi, Kiyoko Takane, Sho Tabata, Tsuneo Ikenoue, Yoichi Furukawa. The Wnt/β-catenin signaling pathway regulates cellular metabolism through the suppression of HAL and ARG1 in liver cancer cells abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 7079.
Nakagawa et al. (Fri,) studied this question.