Expression of Smad4, E-cadherin and beta-catenin in advanced colorectal cancer: a retrospective study

To correlate the expression of E-cadherin and beta-catenin with alterations of expression of Smad4 in advanced colorectal cancer (CRC).

Tissue specimens from 75 colorectal cancer cases (Dukes stage C and D) were tested for Smad4, E-cadherin and beta-catenin by the Avidin-Biotin immunoperoxidase method. The results were correlated with patients' clinicopathological parameters.

Smad4 expression was lost or reduced in roughly 1 out of every 3 Dukes C and D CRCs. Association of Smad4 expression with other clinicopathological parameters was not noted. Association of expression of E-cadherin with other clinicopathological parameters was not noted, apart from tumor location. Expression of beta-catenin was not associated with clinicopathological parameters. Lack of expression of Smad4 was associated with lack of expression of both E-cadherin (<0.000) and beta-catenin (p<0.000). As regards the relation between E-cadherin and beta-catenin, the expression of each seemed to parallel the expression of the other (p<0.000). Beta-catenin was overexpressed in 68.5% of the specimens studied.

Clinically advanced CRC is associated with a reduced or complete lack of expression of Smad4. Ecadherin and beta-catenin are expressed in parallel with each other and also with Smad4. This tumor suppressor role of Smad4 by affecting both E-cadherin and beta-catenin may indicate a novel pathway for metastatic tumor via cellular reshaping. The precise underlined mechanism(s) and the clinical significance of these findings remain to be determined.