Somatic molecular changes and histo-pathological features of colorectal cancer in Tunisia

Abstract

To determine correlations between family history, clinical features and mutational status of genes involved in the progression of colorectal cancer (CRC). Histo-pathological features and molecular changes [KRAS, BRAF and CTNNB1 genes mutations, microsatellite instability (MSI) phenotype, expression of mismatch repair (MMR) and mucin (MUC) 5AC proteins, mutation and expression analysis of TP53, MLH1 promoter hypermethylation analysis] were examined in a series of 51 unselected Tunisian CRC patients, 10 of them had a proven or probable hereditary disease, on the track of new tumoral markers for CRC susceptibility in Tunisian patients. As expected, MSI and MMR expression loss were associated to the presence of familial CRC (75% vs 9%, P < 0.001). However, no significant associations have been detected between personal or familial cancer history and KRAS (codons 12 and 13) or TP53 (exons 4-9) alterations. A significant inverse relationship has been observed between the presence of MSI and TP53 accumulation (10.0% vs 48.8%, P = 0.0335) in CRC tumors, suggesting different molecular pathways to CRC that in turn may reflect different environmental exposures. Interestingly, MUC5AC expression was significantly associated to the presence of MSI (46.7% vs 8.3%, P = 0.0039), MMR expression loss (46.7% vs 8.3%, P = 0.0039) and the presence of familial CRC (63% vs 23%, P = 0.039). These findings suggest that MUC5AC expression analysis may be useful in the screening of Tunisian patients with high risk of CRC.