Vl. Green et al., 17 beta-hydroxysteroid dehydrogenase type 1, 2, 3, and 4 expression and enzyme activity in human anterior pituitary adenomas, J CLIN END, 84(4), 1999, pp. 1340-1345
17 beta-Hydroxysteroid dehydrogenase (17 beta HSD) isoforms reversibly cata
lyze the final step in the formation of estradiol (E-2) from estrone (E-1)
and the formation of testosterone from androstenedione, We have investigate
d 17 beta HSD type 1, 2, 3, and 4 gene expression and 17 beta HSD estrogeni
c activity in human anterior pituitary adenomas. 17 beta HSD messenger ribo
nucleic acid (mRNA) expression was studied by RTPCR in 42 pituitary tumors
and 3 normal pituitaries, 17 beta HSD activity was studied in II tumors and
17 beta HSD type 1 was immunolocalized in vitro in 6 tumors. 17 beta HSD t
ype 1 gene expression was detected in 34 of 42 adenomas in all tumor subtyp
es; 17 beta HSD type 2 mRNA was detected in 18 of 42 adenomas, but not in p
rolactinomas; 17 beta HSD type 3 mRNA was detected in 12 of 42 adenomas, bu
t not in corticotropinomas; 17 beta HSD type 4 was expressed in 20 of 42 ad
enomas by all adenoma subtypes. Reversible 17 beta HSD activity was found i
n 9 of II adenomas, and 17 beta HSD type 1 immunopositivity was cytoplasmic
ally distributed in all 6 adenomas in vitro. All 4 17 beta HSD isoforms are
variably expressed in human anterior pituitary adenomas, which also show 1
7 beta HSD enzyme activity, suggesting that 17 beta HSD may play an importa
nt role in regulating the local cellular levels of estradiol. (J Clin Endoc
rinol Metab 84: 1340-1345, 1999!).