Premium
High extracellular calcium increases the production of a parathyroid hormone‐like activity by cultured leydig tumor cells associated with humoral hypercalcemia
Author(s) -
Rizzoli R.,
Bonjour J.P.
Publication year - 1989
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650040608
Subject(s) - cycloheximide , endocrinology , medicine , extracellular , parathyroid hormone , calcium , parathyroid chief cell , cell culture , biology , chemistry , microbiology and biotechnology , genetics
Cultured Leydig tumor cells produce a parathyroid hormone (PTH)‐like activity, but little is known about the regulation of the release of this factor. In the present work, we investigated the influence of the extracellular calcium concentration on the production of adenylate cyclase‐stimulating activity, as evaluated in the osteoblast‐like PTH‐responsive cell line UMR 106. Medium conditioned in the presence of 0.4 mM or 3 mM Ca elicited a 5.8 ± 0.4‐fold and 10.3 ± 0.9‐fold increase over basal of cAMP production, respectively ( p < 0.001, n = 11 experiments). This effect, which was selective for PTH‐like activity, was detectable after 2 h of incubation and maximal at 6–14 h. It was abolished by the protein synthesis inhibitor cycloheximide, but not by actinomycin D or cordycepin, suggesting a post‐transcriptional site of action. Thus, the production of a tumoral circulating factor implicated in the pathogenesis of humoral malignant hypercalcemia may be influenced in a positive way by an increase in extracellular calcium concentration.