Relationship of mismatch repair proteins and survivin in colon polyps and carcinomas

Mismatch repair genes (MMR) play an essential role in DNA repair. MMR mutations predominantly in MLH1, MSH2, MSH6, PMS2, and rarely in PMS1, may cause the production of abnormally short or inactivated proteins. The antiapoptotic protein survivin functions in the inhibition of apoptosis, regulation of cell division and also enhances angiogenesis. Both MMRP and survivin are considered to be powerful prognostic parameters. This study was designed to determine the relationship between MMRP and survivin in colon lesions. The study included 113 cases of colon carcinoma and 51 cases of colon polyps. Survivin expression and MMRP status were assessed by immunohistochemistry. In each section, expression, intensity of immunostaining and percentage of labeled cells were analyzed. In carcinomas, immunoreaction was detected in 100/113 cases for MLH1 (88.5%), 112/113 cases for MSH2 (99.1%), 110/113 cases for MSH6 (97.3%), and 103/113 cases for PMS2 (91.2%). Survivin was shown in 47/113 cases (41.6%). The statistical analysis confirmed a significant correlation between the expression of MMRP and survivin in the assessed parameters. All 51 polyp samples were positive for MLH1, MSH2, MSH6 and PMS2. Only 8 of those (15.7%) were positive for survivin. Statistically significant differences were observed between the expression of MMRP and survivin. In conclusion, this study revealed that MMRP may suppress the antiapoptotic function of survivin through p53 inactivation of its promoter in grade 1 and grade 2 colon carcinomas.