Molecular Mechanisms of Synergistic Effect of PRIMA-1met and Oxaliplatin in Colorectal Cancer With Different p53 Status.

Background: The toxicity and drug resistance associated with oxaliplatin (L-OHP) limit its long-term use for colorectal cancer (CRC) patients. p53 mutation is a common genetic trait of CRC. PRIMA-1^met (APR-246, eprenetapopt) restores the DNA-binding capacity of different mutant P53 proteins. PRIMA-1^met has progressed to the Phase III clinical trial. Our study explores the combination therapy of PRIMA-1^met and L-OHP for CRC with different p53 status.

Methods: Cell viability was assessed with Cell Counting Kit-8 (CCK-8) assay and combination index (CI) was calculated using The Chou-Talalay method. We also employed wound healing assay and colony formation assay to determine the effect of L-OHP, PRIMA-1^met and their combination. Weighted gene co-expression network analysis (WGCNA) of RNA-seq data was conducted to identify key modules and central genes related to different treatment modalities. Xenograft CRC mouse model was used to assess the combination treatment in vivo.

Results: Our findings showed heightened cytotoxicity and inhibition of migration, and colony formation in CRC cells treated with both drugs, irrespective of p53 status, presenting a promising avenue for addressing L-OHP resistance and toxicity. RNA-seq analysis revealed differential responses between p53-wide type HCT116 and p53-mutant DLD-1 cells, with pathway alterations implicated in tumorigenesis. WGCNA identified key modules and hub genes associated with combination therapy response. In vivo studies demonstrated enhanced efficacy of combined therapy over PRIMA-1^met alone, while mitigating L-OHP-induced toxicity.

Conclusions: In summary, our research reveals the differential molecular mechanisms of combined PRIMA-1^met and L-OHP in CRC with wild type p53 and mutant p53. Our data not only demonstrate that this combined regimen exerts synergistic anti-CRC effect in vitro and in vivo, but also suggest the benefit of PRIMA-1^met on prevention of L-OHP-related side effects. These findings underscore the clinical potential of PRIMA-1^met-L-OHP combination therapy in CRC, offering enhanced efficacy and reduced toxicity, warranting further clinical investigation.