Integrated, genome-wide screening for hypomethylated oncogenes in salivary gland adenoid cystic carcinoma

Salivary gland adenoid cystic carcinoma (ACC) is a rare malignancy amongst head and neck tumors that is poorly understood on a molecular level. We sought to perform a comprehensive approach for novel oncogene candidate screening under the control of promoter methylation in order to learn more about the molecular basis of this unusual disease. We performed global demethylation of normal salivary gland cell strains using 5-aza-deoxycytidine (5-Aza dC) and trichostatin (TSA). Expression arrays were performed, and the profiles of treated and untreated cells compared. We then used expression microarray analysis of primary ACC and normal salivary gland samples to generate ACC-specific expression profiling. Next, we integrated the two profiles to identify a subset of genes for further validation of decreased methylation in the promoter region in ACC vs normals. Finally, only genes that showed decreased methylation in ACC compared to normal were further validated for mRNA, protein, and promoter methylation levels in a larger ACC cohort.