Pathological significance of connexin 26 expression in colorectal adenocarcinoma

This study was conducted to determine the level of expression and cellular localization of connexin 26 (Cx26) and the expression of p53 in colorectal adenocarcinoma as well as their relationship to clinicopathological features. Immunohistochemical staining was performed in 130 colorectal adenocarcinoma cases. A correlation between the expression levels of the two proteins and an analysis of the clinicopathological features of the samples was performed. There was a statistical significant difference in the Cx26 expression level among normal epithelium (NE), adenomas and adenocarcinomas (p<0.001). Of the 130 adenocarcinomas, 48.5% were positive for Cx26. All of the adenoma and NE samples were positive for Cx26 expression; however, the level of expression of Cx26 in adenomas was smaller than the level of expression for NE. Cytoplasmic staining for Cx26 was observed in the adenocarcinomas (23.8%), but was not observed in the adenoma and NE samples. A positive correlation between a reduction in intercellular Cx26 and tumor invasion was statistically significant (p<0.05). Expression of p53 was positive for 50% of the adenocarcinomas, and the level of p53 was increased in a reverse proportion to the level of Cx26 intercellular staining. In conclusion, loss of intercellular and gain of intracytoplasmic Cx26 expression may play a role in colorectal carcinogenesis and tumor progression.