WISP-2 expression in human salivary gland tumors

This study was designed to disclose detailed genetic mechanisms in salivary gland tumors (SGTs) for development of novel independent marker. We constructed an in-house cDNA microarray carrying 2,201 cDNA clones derived from SGT and oral squamous cell carcinoma cDNA libraries. Four cell lines that originated from the SGT-derived cell lines were analyzed using this microarray system. The genes identified by our microarray system were further analyzed at the mRNA or protein expression level in other types of human cancer cell lines and clinical samples (ten normal salivary glands [NSGs], eleven pleomorphic adenomas, ten adenoid cystic carcinomas and three adenocarcinomas). Two up-regulated genes and six down-regulated genes were identified in common when compared with the control RNA. Of the up-regulated genes, WISP-2, which plays an important role in breast carcinogenesis, was selected for further analyses. We found a higher expression of the WISP-2 gene in the SGT-derived cell lines compared with other types of human cancer cell lines. Furthermore, WISP-2 mRNA and protein expression levels in NSGs were significantly higher than those in SGTs. These results suggest that WISP-2 could be a reliable independent marker and that down-regulation or loss of the WISP-2 gene may be associated with the development of SGTs.