Influence of Citrobacter freundii on NINJ2 Expression and Oxaliplatin Resistance in Colorectal Cancer

Oxaliplatin, a third-generation platinum-based chemotherapeutic agent, is widely used in the treatment of colorectal cancer (CRC). However, some patients do not respond effectively to oxaliplatin, and intrinsic resistance to the drug poses a significant challenge. Recent studies have revealed an association between the gut microbiome and the progression of CRC. We hypothesized that Citrobacter freundii, a component of the gut microbiome, contributes to oxaliplatin resistance by regulating specific gene expression in CRC cells.

A bacterial culture filtrate from Citrobacter freundii was employed in the experiments. The CRC cell line RKO, following exposure to this filtrate, was analyzed using high-throughput RNA sequencing. Candidate genes were identified through MTT assays, siRNA knockdown, and overexpression experiments. Apoptosis and reactive oxygen species (ROS) assays were performed to investigate the underlying mechanisms. Finally, a xenograft mouse model was used to evaluate oxaliplatin resistance in vivo.

Exposure to bacterial culture filtrate from Citrobacter freundii induced oxaliplatin resistance in RKO cells with downregulation of the NINJ2 gene as a possible molecular mechanism. ReducedNINJ2 gene expression suppressed oxaliplatin-induced apoptosis and ROS generation. A tendency toward reduced oxaliplatin efficacy was observed in vivo when NINJ2 gene expression was suppressed.

This study demonstrates that Citrobacter freundii promotes oxaliplatin resistance in CRC through downregulation of NINJ2 gene. NINJ2 gene may serve as a predictive biomarker and therapeutic target to overcome oxaliplatin resistance in CRC.