P-cadherin overexpression Is an indicator of clinical outcome in invasive breast carcinomas and is associated with CDH3 promoter hypomethylation

Purpose: P-cadherin overexpressionhas been reported in breast carcinomas,where itwas associated with proliferative high-grade histological tumors. This study aimed to analyze P-cadherin expression in invasive breast cancer and to correlate it with tumor markers, pathologic features, and patient survival. Another purpose was to evaluate the P-cadherin promoter methylation pattern as the molecularmechanismunderlying this gene regulation. Experimental Design: Using a series of invasive breast carcinomas, P-cadherin expressionwas evaluated and correlated with histologic grade, estrogen receptor, MIB-1, and p53 and c-erbB-2 expression. In order to assess whether P-cadherin expression was associated with changes in CDH3 promoter methylation, we studied the methylation status of a gene 5V-flanking region in these same carcinomas.This analysis was also done for normal tissue and for a breast cancer cell line treatedwith a demethylating agent. Results: P-cadherinexpression showeda strong correlationwithhighhistologic grade, increased proliferation, c-erbB-2 and p53 expression, lack of estrogen receptor, and poor patient survival. This overexpressioncanbe regulatedby gene promotermethylationbecause the 5-Aza-2V-deoxycytidine treatment ofMCF-7/AZ cells increased P-cadherinmRNA and proteinlevels. Additionally, we found that 71% of P- adherin-negative cases showed promoter methylation,whereas 65% of positive ones were unmethylated (P = 0.005). The normal P-cadherin-negative breast epithelial cells showed consistent CDH3 promotermethylation. Conclusions: P-cadherin expressionwas strongly associatedwith tumor aggressiveness, being a good indicator of clinical outcome. Moreover, the aberrant expression of P-cadherin in breast cancermight be regulated by gene promoter hypomethylation