Potentiating BSEP-mediated bile acid efflux reverses first-line tyrosine kinase inhibitor resistance in hepatocellular carcinoma.

Wu Z, Wang Y, Yu B, Yu R, Chen M, Chen Z, Shan J, Ding Z, Li J, Jin X, Chen Y, Wang L, Zhu H, Zhu W, Pan Q, Zhang T, Zhang Y, Lv L, Wang L, Zhao Y

Cancer letters 2026

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Tyrosine kinase inhibitor (TKI) resistance limits therapy for hepatocellular carcinoma (HCC). Integrating RNA-seq and public cohort data, we found consistent downregulation of the bile salt export pump (BSEP/ABCB11) in TKI-resistant HCC associated with poorer prognosis and reduced clinical response. Functional in vitro and xenograft studies, using BSEP overexpression/knockdown and TKI-resistant cell lines plus targeted metabolomics, showed BSEP expression deficiency leads to intracellular accumulation of primary conjugated bile acids (BAs)-especially glycocholic acid (GCA)-which activates EGFR signaling and drives resistance; restoring BSEP enhances BA efflux and resensitizes cells and tumors to TKIs. Mechanistic assays revealed that ursodeoxycholic acid (UDCA) upregulated BSEP and reversed resistance via an FXR-independent mechanism: UDCA directly binds cortactin (CTTN), reduces its PRMT1-dependent mono-methylation, and promotes CTTN degradation via chaperone-mediated autophagy (CMA), thereby enabling YY1 nuclear translocation and transcriptional activation of BSEP. Clinical specimen analyses corroborated an inverse BSEP-CTTN relationship and UDCA modulation. These findings identify impaired BSEP-mediated BA efflux and GCA accumulation as metabolic features of TKI resistance and support targeting the CTTN/YY1/BSEP axis, including UDCA, to overcome resistance.