Mutations in CTNNB1 and in the TERT promoter are among the most prevalent genetic alterations in hepatocellular carcinoma (HCC), yet their functional cooperation in hepatocarcinogenesis remains poorly defined. This study aimed to elucidate the molecular interplay between β-catenin and TERT in driving liver tumorigenesis.

The Cancer Genome Atlas (TCGA) data were used to analyze mutations in CTNNB1 and in the TERT promoter in HCC samples. Plasmids encoding activated β-catenin (Δ90 β-catenin) and TERT were introduced into mouse livers using the hydrodynamic tail vein injection (HTVI). Tumor development was monitored over time, and immunohistochemical analyses were performed to identify activated signaling pathways in tumor cells.

Analysis of publicly available genomic datasets revealed a significant genetic association between CTNNB1 and TERT promoter mutations in hepatocellular carcinoma (HCC) (Fisher’s exact test, P < 0.01), suggesting that their co-occurrence may confer a selective advantage during hepatocarcinogenesis. Coexpression of Δ90 β-catenin and TERT induced rapid HCC formation, whereas expression of either Δ90 β-catenin or TERT alone produced minimal or no tumors, respectively. Immunohistochemical analyses revealed that tumors driven by β-catenin and TERT exhibited strong phosphorylation of ERK1/2, indicative of MAPK/ERK pathway activation. Genetic knockdown of MEK1/2, the upstream ERK1/2 kinases, markedly suppressed tumor formation in the liver, confirming that MAPK/ERK signaling is essential for β-catenin and TERT–driven hepatocarcinogenesis.

These findings demonstrate a synergistic oncogenic interaction between β-catenin and TERT that critically depends on MAPK/ERK pathway activation. The study provides mechanistic insight into the frequent co-occurrence of CTNNB1 and TERT promoter mutations in human HCC and highlights the MAPK/ERK cascade as a potential therapeutic vulnerability in this molecular subtype.