Changes in immunoexpression of p53, Ki-67, Ets-1, APAF-1 and PTEN in serrated and conventional colon adenomas

The balance between apoptosis and proliferation is tipped towards a decrease of apoptosis as the colonocyte progresses in the adenoma to carcinoma sequence of colon carcinogenesis. According to literature data, proteins like p53, Ki-67, APAF-1, Ets-1, PTEN contribute to inhibition of apoptosis and stimulation of proliferation.

Considering the complex interference among colorectal carcinogenetic mechanisms, our aim was to study the markers Ets-1 and APAF-1 relative to p53, Ki-67 and PTEN expression in colon adenomas/polyps (A/P).

We performed immunohistochemistry on 99 colon A/P cases from the material of the Department of Pathology, Emergency County Hospital of Tirgu Mures, Romania. Secondary EnVision Flex/HRP (Horseradish peroxidase) (20 minutes) was used for signal amplification.

The majority of A/P show increased Ki-67, p53, Ets-1 expression, decreased APAF-1 expression and preserved PTEN expression. p53, Ki-67, Ets-1 and APAF-1 demonstrated statistically significant correlations with histological type and grade of dysplasia. We also observed that expression of these proteins in the intestinal crypts has a typical distribution according to histological type and grade of dysplasia.

In case of hyperplastic polyps APAF-1 expression decreases as p53 and Ki-67 expression increases, followed by a decrease in PTEN expression in serrated adenomas, and an increase of Ets-1 expression in conventional adenomas.