Imunoexpressão das proteínas COX-2, p53 e caspase-3 em adenoma colorretal e mucosa não neoplásica

Abstract

Objective:To analyze the immunoexpression of the COX-2, p53, and caspase-3 proteins in colorectal adenomas and non-neoplastic mucosa.Methods:72 individuals were subjected to colonoscopy, which provided 50 samples of adenomas and 45 samples of non-neoplastic colorectal mucosa. The tissue samples were obtained via the tissue microarray technique and subjected to immunohistochemical analysis using primary anti-p53, anti-COX-2, and anti-caspase-3 antibodies. The positivity and intensity of the immunoreaction were classified. The analyzed variables were as follows: site of the adenomas in the colon, degree of dysplasia, size, and score of positivity and intensity of immunoexpression of the p-53, caspase-3, and COX-2 proteins.Results:The immunoexpression of mutated protein p53 was positive in 30 (60%) adenoma samples and negative in 20 (40%) adenoma samples. The immunoexpression of mutated protein p53 was negative in 39 (86.6%) samples and positive in 6 (13.3%) samples of the non-neoplastic colorectal mucosa (p<0.0001). Significant differences were seen between both the largest size (p=0.006) and the highest degree of dysplasia (p<0.0001) of the adenomas and the intensity of immunoexpression of mutated protein p53. The positivity and intensity of immunoexpression of COX-2 (p=0.14) and caspase-3 (p=0.23) showed no significant differences between the adenomas and the non-neoplastic colorectal mucosa.Conclusion:Mutated protein p53 was hyperexpressed in the adenomas compared with the non-neoplastic mucosa. Greater size and greater degree of dysplasia in the adenomas were associated with higher expression of mutated protein p53. The immunoexpression of COX-2 and caspase-3 in the adenomas did not exhibit a correlation with the anatomical-pathological features of the tumors and did not differ from the corresponding expression levels in the non-neoplastic mucosa.

Impact of cyclooxygenase-2 over-expression on the prognosis of colorectal cancer patients

“… 23 In contrast, a group of scientists from Brazil, in a study using TmA and IHC on positivity and intensity of COX-2 did not find any significant differences between the adenomas and the non-neoplastic colorectal mucosa. 24 Our findings in the present study are however in concordance with most of the recent works regarding its over-expression and its significance as precancerous marker in the colorectal adenoma-carcinoma sequence.…”

Immunohistochemical expression of heparanase isoforms and syndecan-1 proteins in colorectal adenomas

“… 6 , 7 Genes upregulated in adenoma relative to normal tissue, which maintained increased expression in colorectal carcinoma and adenoma, would encode proteins suitable as putative targets for immunoprevention. 4 , 5 , 8 The identification of early and easily detectable tumor markers that might contribute to the knowledge of colorectal carcinogenesis and the biological mechanisms required for preinvasive adenoma to progress to carcinoma, are highly relevant subjects. 4 , 5 The process of proliferation and tumor invasion depends, among other factors, on changes in the extracellular matrix (ECM) represented by the loss of cell-cell interaction, ECM degradation by tumor cells through activation of enzymes associated with neoplastic invasion that disorganize and fragment the stromal elements and their own ECM, and the synthesis of ECM components by metastatic tumor cells.…”