Identification of differentially expressed genes in salivary gland tumors with cDNA microarray

Objective: The final goal of this study is to develop a pre-operative fine needle aspiration biopsy (FNA) diagnostic system based on gene expression profiles. As the first step to that end, the present study was performed to determine whether the cDNA microarray system is applicable for histological evaluation of parotid gland tumors. Methods: We investigated molecular characteristics on the basis of gene expression patterns of the two most common types of salivary gland tumors (pleomorphic adenomas and Warthin tumors) and normal salivary gland tissues, using the cDNA microarray system. Results: Pleomorphic adenomas and Warthin tumors can be classified by cDNA microarray. In pleomorphic adenomas, 11 independent genes were found to be up-regulated and 2 genes were down-regulated. In Warthin tumors, five independent genes were found to be up-regulated, and six genes were down-regulated. In hierarchical clustering analysis, cases were further grouped into two clusters according to the histological type. Furthermore, cDNA microarray enabled pleomorphic adenomas to be subclassified into three clusters according to the histological subtypes. Conclusions: This study suggested that cDNA microarray may be useful and applicable for the pre-operative diagnosis (such as FNA) of the salivary gland tumor.