Microenvironment influence on human colon adenocarcinoma phenotypes and matrix metalloproteinase-2, p53 and β-catenin tumor expressions from identical monoclonal cell tumor in the orthotopic model in athymic nude rats.

The present study aims to identify differences between left and right colon adenocarcinoma arising from identical clonal cell and to find out if microenvironment has any influence on matrix metalloproteinase-2 (MMP2), p53 and β-catenin tumor expressions. MATERIAL AND METHODS. Rats (RNU) were submitted to cecostomy to obtain the orthotopic model of right colon tumor (n = 10), while for the left colon model (n = 10), a colon diversion and distal mucous fistula in the descending colon was used. Cultivated human colon adenocarcinoma cells (WiDr) were inoculated in stomas submucosa. Histopathological analysis, real-time reverse transcription-PCR for β-catenin, p53 and MMP2, as well as immunohistochemical analysis for p53 and β-catenin expression were conducted. Central tendency, variance analysis and the Livak delta-delta-CT method were used for statistical analysis, adopting a 5% significance level. RESULTS. All tumors from the left colon exhibited infiltrative ulceration, while in the right colon tumor growth was predominantly exophytic (67%). In the left colon, tumor growth was undifferentiated (100%), while it was moderately differentiated in the right colon (83%). In right colon tumors, MMP2, p53, and β-catenin gene expressions were higher than compared to left colon (p = 4.59354E-05, p = 0.0035179, p = 0.00093798, respectively, for MMP2, p53 and β-catenin). β-catenin and p53 results obtained by real-time polymerase chain reaction were confirmed by immunohistochemistry assay (p = 0.01 and p = 0.001, respectively, for β-catenin and p53). CONCLUSION. Left and right human colon adenocarcinomas developed in animal models have distinct phenotypes even when they have the same clonal origin. Microenvironment has influenced p53, β-catenin, and MMP2 expression in animal models of colon cancer.