Novel patterns of gene expression in pituitary adenomas identified by complementary deoxyribonucleic acid microarrays and quantitative reverse transcription-polymerase chain reaction

Pituitary adenomas account for approximately 10% of intracranial tumors, bu t little is known of the oncogenesis of these tumors. The identification of tumor-specific genes may further elucidate the pathways of tumor formation . We used complementary DNA microarrays to examine gene expression profiles in nonfunctioning, PRL, GH, and ACTH secreting adenomas, compared with nor mal pituitary. Microarray analysis showed that 128 of 7075 genes examined w ere differentially expressed. We then analyzed three genes with unique expr ession patterns and oncogenic importance by RT-real time quantitative PCR i n 37 pituitaries. Folate receptor gene was significantly overexpressed in n onfunctioning adenomas but was significantly underexpressed in PRL and GH a denomas, compared with controls and to other tumors. The ornithine decarbox ylase gene was significantly overexpressed in GH adenomas, compared with ot her tumor subtypes but was significantly underexpressed in ACTH adenomas. C -mer proto-oncogene tyrosine kinase gene was significantly overexpressed in ACTH adenomas but was significantly underexpressed in PRL adenomas. We hav e shown that at least three genes involved in carcinogenesis in other tissu es are also aberrantly regulated in the major types of pituitary tumors. Th e evaluation of candidate genes that emerge from these experiments provides a rational approach to investigate those genes significant in tumorigenesi s.