PARP-1 selectively impairs <i>KRAS</i>-driven phenotypic and molecular features in intrahepatic cholangiocarcinoma.

Abstract

Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver cancer with limited therapeutic options. <i>KRAS</i> mutations are among the most abundant genetic alterations in iCCA associated with poor clinical outcome and treatment response. Recent findings indicate that Poly(ADP-ribose)polymerase1 (PARP-1) is implicated in <i>KRAS</i>-driven cancers, but its exact role in cholangiocarcinogenesis remains undefined. <i>PARP-1</i> inhibition was performed in patient-derived and established iCCA cells using RNAi, CRISPR/Cas9 and pharmacological inhibition in <i>KRAS</i>-mutant, non-mutant cells. In addition, <i>Parp-1</i> knockout mice were combined with iCCA induction by hydrodynamic tail vein injection to evaluate an impact on phenotypic and molecular features of <i>Kras</i>-driven and <i>Kras</i>-wildtype iCCA. Clinical implications were confirmed in authentic human iCCA. PARP-1 was significantly enhanced in <i>KRAS</i>-mutant human iCCA. PARP-1-based interventions preferentially impaired cell viability and tumourigenicity in human <i>KRAS</i>-mutant cell lines. Consistently, loss of <i>Parp-1</i> provoked distinct phenotype in <i>Kras/Tp53-</i>induced versus <i>Akt/Nicd-</i>induced iCCA and abolished <i>Kras</i>-dependent cholangiocarcinogenesis. Transcriptome analyses confirmed preferential impairment of DNA damage response pathways and replicative stress response mediated by CHK1. Consistently, inhibition of CHK1 effectively reversed PARP-1 mediated effects. Finally, <i>Parp-1</i> depletion induced molecular switch of <i>KRAS</i>-mutant iCCA recapitulating good prognostic human iCCA patients. Our findings identify the novel prognostic and therapeutic role of <i>PARP-1</i> in iCCA patients with activation of oncogenic <i>KRAS</i> signalling.