Association of the p53 codon 72 polymorphism with clinicopathological characteristics of colorectal cancer through mRNA analysis

Potential role of PIN1 genotypes in predicting benefit from oxaliplatin-based and irinotecan-based treatment in patients with metastatic colorectal cancer

PIN1-mediated substrate isomerization plays a role in the repair of DNA double-strand breaks. We hypothesized that genetic polymorphisms in PIN1-related pathways may affect tumor sensitivity to oxaliplatin or irinotecan in metastatic colorectal cancer (mCRC) patients. We analyzed genomic DNA from five cohorts of mCRC patients (total 950) treated with different first-line treatments: oxaliplatin cohorts 1 (n=146) and 2 (n=70); irinotecan cohorts 1 (n=228) and 2 (n=276); and combination cohort (n=230). Single nucleotide polymorphisms of candidate genes were analyzed by PCR-based direct sequencing. In the oxaliplatin cohort 1, patients carrying any PIN1 rs2233678 C allele had shorter progression-free survival (PFS) and overall survival (OS) than the G/G variant (PFS, 7.4 vs. 15.0 months, hazard ratio [HR] 3.24, P<0.001; OS, 16.9 vs. 31.5 months, HR: 2.38, P=0.003). In contrast, patients with C allele had longer median PFS than patients with G/G (11.9 vs. 9.4 months, HR: 0.64, 95%CI: 0.45–0.91, P=0.009) in the irinotecan cohort 1. No significant differences were observed in the combination cohort. In comparison between the irinotecan cohort 1 and combination cohort, the patients carrying the G/G variant benefit greatly from the combination compared with irinotecan-based regimen (PFS, 11.6 vs. 9.4 months, HR 0.61, 95%CI: 0.47–0.78, P<0.001; OS, 30.6 vs. 24.0 months, HR 0.79, 95%CI: 0.62–1.02, P=0.060), while no significant difference was shown in any C allele. Germline PIN1 polymorphisms may predict clinical outcomes in mCRC patients receiving oxaliplatin- or irinotecan-based therapy, and identify specific populations favorable to oxaliplatin plus irinotecan combination therapy.

Molecular biomarkers in colorectal carcinoma

Colorectal cancer is a tumor with increasing incidence which represents one of the first leading causes of death worldwide. Gene alterations described for colorectal cancer include genome instability (microsatellite and chromosomal instability), CpG islands methylator phenotype, microRNA, histone modification, protein biomarkers, gene mutations (RAS, BRAF, PI3K, TP53, PTEN) and polymorphisms (APC, CTNNB1, DCC). In this article, biomarkers with prognostic value commonly found in colorectal cancer will be reviewed.