MATERIAL and METHODS: RNA was extracted and purified from pituitary adenomas (10 non-functioning and 10 gonadotropin-secreting) and from two normal pituitary tissue samples. The samples were analyzed by miRNA microarray. Gene expression was measured using realtime RT-PCR with SYBR GREEN I.

RESULTS: In non-functioning pituitary adenomas, 25 miRNA genes were up-regulated (six by over 5-fold) and 15 were down-regulated (six by more than 10-fold). miR-124a was the most up-regulated gene (38.58-fold), and miR-31 the most down-regulated gene (21.5-fold). In gonadotropin-secreting pituitary adenomas, 16 miRNA genes were up-regulated (six by over 4-fold) and 13 were down-regulated (seven by more than 10-fold). miR-10b was the most up-regulated gene (48.73-fold), and miR-503 the most down-regulated gene (39.8-fold). Five genes were up-regulated in both subtypes: miR-523, miR-10b, miR-520b, miR-422a, and miR-422b. The RT-PCR results were consistent with those of the gene chips.

CONCLUSION: We established miRNA expression maps of non-functioning and gonadotropin-secreting pituitary adenomas. The most strongly differentially expressed genes were miR-124a and miR-31 in non-functioning pituitary adenomas, and miR-10b and miR-503 in gonadotropin-secreting pituitary adenomas. Keywords : Pituitary adenoma, miRNA gene, Gene chip