X-ray repair cross-complementing protein 1 (XRCC1) loss promotes β-lapachone -induced apoptosis in pancreatic cancer cells

β-lapachone (β-lap), the NQO1 bioactivatable drug, is thought to be a promising anticancer agent. However, the toxic side effects of β-lap limit the drug use, highlighting the need for a thorough understanding of β-lap's mechanism of action. β-lap undergoes NQO1-dependent futile redox cycling, generating massive ROS and oxidative DNA lesions, leading to cell death. Thus, base excision repair (BER) pathway is an important resistance factor. XRCC1, a scaffolding component, plays a critical role in BER.

These results indicate that XRCC1 is involved in the repair of β-lap-induced DNA damage, and XRCC1 loss amplifies sensitivity to β-lap, suggesting targeting key components in BER pathways may have the potential to expand use and efficacy of β-lap for gene-based therapy.

We knocked down XRCC1 expression by using pLVX-shXRCC1 in the MiaPaCa2 cells and BxPC3 cells and evaluated β-lap-induced DNA lesions by γH2AX foci formation and alkaline comet assay. The cell death induced by XRCC1 knockdown + β-lap treatment was analysed by relative survival, flow cytometry and Western blotting analysis.

We found that knockdown of XRCC1 significantly increased β-lap-induced DNA double-strand breaks, comet tail lengths and cell death in PDA cells. Furthermore, we observed combining XRCC1 knockdown with β-lap treatment switched programmed necrosis with β-lap monotherapy to caspase-dependent apoptosis. Conclusions: These results indicate that XRCC1 is involved in the repair of β-lap-induced DNA damage, and XRCC1 loss amplifies sensitivity to β-lap, suggesting targeting key components in BER pathways may have the potential to expand use and efficacy of β-lap for gene-based therapy.