Differential effects of insulin-like growth factor 1 on the hormonal product and proliferation of glycoprotein-secreting human pituitary adenomas.
The effects of human recombinant insulin-like growth factor 1 (IGF-1) on the secretion, viability, and proliferation of dispersed human anterior pituitary adenomas secreting FSH, LH, and alpha-subunit (alpha-su) were examined in vitro over 4 h and 4 days. The acute effect of IGF-1 on secretion over 4 h was examined in four tumors secreting FSH, LH, and alpha-su. IGF-1 (100 nmol/L) reduced LH compared to control (100%) in one tumor (61%, P < 0.01), and three tumors remained unaffected. FSH and alpha-su secretion were insufficient to measure over 4 h. Nine tumors were studied over 4 days; relative to control, IGF-1 (100 nmol/L) increased FSH secretion in all seven tumors secreting FSH (28-266%, P < 0.05) and increased alpha-su secretion in all four tumors studied (36%, 63%, 91%, and 121%, P < 0.05). IGF-1 reduced LH secretion in four/nine tumors (13%, 23%, 32%, and 50%, P < 0.05). Dose response curves (1-100 nmol/L IGF-1) were performed on three tumors cosecreting FSH and LH. Stimulation of FSH was achieved with either 1 or 10 nmol/L IGF-1, a single tumor in which alpha-su was measured showed maximal stimulation at 10 nmol/L IGF-1, and one of three tumors showed LH inhibition with 100 nmol/L IGF-1. In situ viability of attached cells was assessed with fluorescein and propidium iodide in seven tumors. After 4 days' exposure to 100 nmol/L IGF-1, in situ viability was increased in five tumors (range 12-19%, 15 +/- 1.3% SEM, P < 0.05). The effects of IGF-1 on the adenoma cell proliferative S-phase fraction was determined in six tumors after 4 days of treatment using double immunostaining with bromodeoxyuridine incorporation for 1 h. In four/six adenomas that stained positive for bromodeoxyuridine in the controls (1-5.6%), the S-phase fraction was increased by 100 nmol/L IGF-1 [(range 2.1-10.6%, increase 90-220%) (P < 0.05)]. These results show that IGF-1 has differential effects on gonadotropins from human pituitary adenomas, stimulating intact FSH and alpha-su, inhibiting or being without effect on intact LH in vitro, and increasing both viability and number of tumorous glycoprotein-secreting cells entering into the S-phase of proliferation.
Atkin
S L
SL
University Department of Medicine and Chemical Pathology, Liverpool, United Kingdom.
Landolt
A M
AM
Jeffreys
R V
RV
Hipkin
L
L
Radcliffe
J
J
Squire
C R
CR
White
M C
MC
D000236:Adenoma / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005260:Female; D005640:Follicle Stimulating Hormone / Q000096:biosynthesis; D015292:Glycoprotein Hormones, alpha Subunit / Q000378:metabolism; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology* / Q000502:physiology; D007986:Luteinizing Hormone / Q000096:biosynthesis; D008297:Male; D008875:Middle Aged; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D010908:Pituitary Hormones, Anterior / Q000378:metabolism*; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology; D011994:Recombinant Proteins / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D015292:Glycoprotein Hormones, alpha Subunit; D010908:Pituitary Hormones, Anterior; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone