Tissue Factor Pathway Inhibitor 2 Enhances Hepatocellular Carcinoma Chemosensitivity by Activating CCAR2-GADD45A-Mediated DNA Damage Repair

Chemotherapy resistance presents a major challenge in the treatment of hepatocellular carcinoma (HCC), with the underlying molecular mechanisms largely unknown. This study aimed to investigate the role of tissue factor pathway inhibitor 2 (TFPI2) in modulating HCC chemosensitivity. We explored the impact of TFPI2 on sorafenib sensitivity in patient-derived organoids and mouse models using immunofluorescence analysis, chromatin immunoprecipitation, and RNA immunoprecipitation. We observed the downregulation of TFPI2 in HCC, and its deletion in mice (TFPI2^HKO) accelerated DEN-induced liver tumorigenesis. Notably, TFPI2 overexpression increased sorafenib sensitivity in HCC organoids and <i>in vivo</i> models. Mechanistic insights indicated that TFPI2 stabilizes the mRNA of growth arrest and DNA damage-inducible alpha (GADD45A) by engaging the cell cycle and apoptosis regulator 2 (CCAR2), promoting GADD45A-mediated DNA damage and inhibiting homologous recombination repair. Furthermore, TFPI2 protects CCAR2 from ubiquitination-induced degradation by associating with the deubiquitinating enzyme BRCC3. We identified polydatin, a resveratrol glycoside, which upregulates TFPI2 and synergistically enhances the chemosensitizing effect of sorafenib in organoids and <i>in vivo</i>. TFPI2 plays a critical role in CCAR2-GADD45A-induced DNA damage repair, providing a strategy to enhance HCC chemosensitivity. Our findings elucidate the molecular intricacies of chemoresistance in HCC and reveal a potential therapeutic target for alleviating this resistance.