Expression of CD44 variants in colorectal carcinoma quantified by real-time reverse transcriptase-polymerase chain reaction.

CD44 is a family of transmembrane glycoproteins that has been linked to carcinogenesis and metastasis. It serves as a major receptor for hyaluronate. The v3 isoform binds to growth factors through heparan sulfate side chains and targets these factors to their high-affinity signal transducing receptors. The purpose of this study was to analyze the expression of CD44 v3 and v4 in human colorectal carcinoma with real-time reverse transcriptase-polymerase chain reaction (RT-PCR). Our results show that 19 of 56 cases (33.9%) showed a greater than 2-fold increase in CD44 v3 expression in tumors as compared with matched normal mucosa, while 15 of 44 cases (34.1%) showed a greater than 2-fold increase in CD44 v4 expression. There was a marked variation in fold-differences of CD44 gene expression between tumor and normal samples (T/N ratios) among the tumors. This prompted us to correlate the T/N ratios of the tumors with clinicopathologic characteristics. Interestingly, overexpression of CD44 v3 mRNA was associated with the presence of vascular invasion (P <.05). Similarly, overexpression of CD44 v4 was significantly correlated to increased depth of invasion (P <.05). Results from the present study suggest that overexpression of CD44 v3 and v4 mRNA levels may be useful clinical markers for colorectal carcinoma invasiveness.