NEIL3 Deficiency Enhances HCC Cell Sensitivity to Oxaliplatin by Inhibiting the Fanconi Anaemia Pathway

Abstract

Despite some achievements in oxaliplatin-based chemotherapy for the treatment of advanced hepatocellular carcinoma (HCC), the abnormal activation of DNA damage repair pathways in HCC cells remains a major problem, limiting the efficacy of oxaliplatin-based chemotherapy. In a previous study, we found that endonuclease VIII-like protein 3 (NEIL3) is expressed in a high proportion of patients with HCC and associated with an unfavourable prognosis. However, the role of NEIL3 in chemoresistance is still unclear. The aim of this study was to evaluate whether and how NEIL3 regulates oxaliplatin anti-tumour efficacy. Gene expression after oxaliplatin treatment in HCC cell lines was assessed by real-time quantitative PCR, western blot analysis and bioinformatics analysis. The effect of NEIL3 on regulating oxaliplatin efficacy was assessed using cell counting kit-8 assays, colony formation assays, flow cytometry and an in vivo nude mice study. Mechanistic insights into the sensitivity to oxaliplatin mediated by the inhibition of NEIL3 were obtained through immunofluorescence and RNA sequencing analyses. Our findings demonstrated that NEIL3 expression was markedly downregulated after oxaliplatin administration. NEIL3 knockdown impaired cell viability and colony formation and increased apoptosis in HCC cells exposed to oxaliplatin. In addition, NEIL3 inhibition reduced tumour progression and enhanced oxaliplatin efficacy in xenograft nude mice models. Furthermore, knocking down NEIL3 significantly increased the oxaliplatin-mediated inhibition of the Fanconi anaemia pathway. Our results revealed that NEIL3 may be a promising therapeutic target for improving oxaliplatin efficacy in the treatment of HCC.