17-Beta-Hydroxysteroid Dehydrogenase Type 1 (HSD17b1)

HSD17B mRNA expression was studied by RT-PCR in 42 pituitary tumors and 3 normal pituitaries, HSD17B activity was studied in 11 tumors, and HSD17B1 was immunolocalized in vitro in 6 tumors. HSD17B1 gene expression was detected in 34 of 42 (81%) adenomas in all tumor subtypes; HSD17B2 mRNA was detected in 18 of 42 (43%) adenomas but not in prolactinomas; HSD17B3 mRNA was detected in 12 of 42 (29%) adenomas but not in corticotropinomas; and HSD17B4 was expressed in 20 of 42 (48%) adenomas by all adenoma subtypes. All 4 HSD17B isoforms were variably expressed in human anterior pituitary adenomas, which also showed HSD17B enzyme activity, suggesting that HSD17B may play an important role in regulating the local cellular levels of estradiol.