DIFFERENTIAL EXPRESSION OF CD44 SPLICE VARIANTS IN MALIGNANT AND BENIGN PLEURAL EFFUSIONS

Expression of CD44 isoform that contains variant exons (v1-v10) has be en implicated in tumor progression and metastasis. Especially, CD44 is oform containing v6 (CD44v6) and that containing v7 (CD44v7) were show n to confer full metastatic behavior on tumor cells. We examined the e xpression of CD44v6 and CD44v7 in malignant pleural effusions (13 lung cancers and 4 non-lung cancers) and in benign pleural effusions (7 tu berculosis and 3 pneumonia) with Southern blot analysis of reverse tra nscription (RT)-polymerase chain reaction (PCR) products. CD44v6 was e xpressed not only in malignant pleural effusions (12 of 13 lung cancer s and 4 of 4 non-lung cancers), but also in benign pleural effusions(9 /10). In contrast, although expression of CD44v7 was found in most mal ignant pleural effusions (12 of 13 lung cancers and 4 of 4 non-lung ca ncers), it mas found in only a few Gases of benign pleural effusions. These results suggest that the expression of CD44v7 may be correlated with a tumor-specific event such as metastasis or dissemination in mal ignant pleural effusion, while no such correlation can be found with C D44v6.