Increased expression of CD44v6 mRNA significantly correlates with distant metastasis and poor prognosis in gastric cancer.

Expression of CD44 and its variants is associated with clinically aggressive behavior of some human cancers. The present study was undertaken to determine the expression level of these CD44 mRNAs in relation to the clinicopathologic features and prognosis of gastric cancer. Using reverse transcription polymerase chain reaction followed by Southern blotting, we examined the expression of the standard and variant (v6 and v9) forms of CD44 mRNA in 73 cases of gastric cancer. We determined the ratio of mRNA expression in cancer tissue to normal tissue (T/N ratio) and evaluated the correlations of the ratio with clinico-pathologic features, tumor progression and prognosis. The expression level of the standard form of CD44 (CD44s) mRNA correlated with peritoneal dissemination only, and that of CD44v9 mRNA did not significantly correlate with any clinicopathologic factor. The expression level of CD44v6 mRNA was significantly higher in patients with lymph node metastasis and liver metastasis. In 48 curatively resected patients, the expression level of CD44v6 mRNA correlated with the site of recurrence. Furthermore, there was a significant survival advantage in patients with low expression of CD44v6 mRNA compared with those with high expression. The level of CD44v6 mRNA expression may be a potential prognostic indicator and may be useful as a predictor for distant metastasis and recurrence in patients with gastric cancer.