The contrasting role of calcium influx in secretion induced by cell swelling can differentiate normal and tumor-derived rat pituitary cells.
We have evaluated whether cell swelling may be a generally useful technique to differentiate normal and neoplastic pituitary cells, making the comparison between normal lactotrophs and thyrotrophs and tumor-derived GH4C1 and MMQ cells. With 1.5 mM medium Ca2+, cell swelling induced by osmotically equivalent stimuli, 27% medium hyposmolarity or 80 mM isotonic urea, caused a prompt increase in both intracellular Ca2+ and hormone secretion by all cell types. Depletion of medium Ca2+ abolished the cell swelling-induced increase in intracellular Ca2+ in all cell types and hormone secretion in the tumor-derived cells. However, it enhanced hormone secretion in normal cells. The critical role of Ca2+ influx in osmotically induced secretion in neoplastic, but not normal, pituitary cells may reflect some fundamental alteration in the intracellular transduction system in tumor cells.
Sato
N
N
Department of Medicine, Oregon Health Sciences University, Portland 97201.
Murakami
M
M
Wang
X B
XB
Greer
M A
MA
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003470:Culture Media; D004563:Electrochemistry; D007552:Isotonic Solutions; D009994:Osmolar Concentration; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism* / Q000473:pathology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012016:Reference Values; D014407:Tumor Cells, Cultured; D014508:Urea / Q000494:pharmacology
D003470:Culture Media; D007552:Isotonic Solutions; D010907:Pituitary Hormones; D014508:Urea; D011188:Potassium; D002118:Calcium