help button home button Endocrine Society Endocrinology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Burtis, W. J.
Right arrow Articles by Stewart, A. F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Burtis, W. J.
Right arrow Articles by Stewart, A. F.

Endocrinology, Vol 118, 1982-1988, Copyright © 1986 by Endocrine Society

ARTICLES

Two species of adenylate cyclase-stimulating activity in a murine squamous carcinoma model of humoral hypercalcemia of malignancy

WJ Burtis, AE Broadus, KL Insogna, EC Weir and AF Stewart

PTH receptor-stimulating proteins may be a common mediator of humoral hypercalcemia of malignancy (HHM). Such proteins exhibit adenylate cyclase-stimulating activity (ACSA) in PTH-sensitive assays, and ACSA has been used to follow their purification. Acid/urea tumor extracts from a murine squamous carcinoma model of HHM were previously shown to have very high ACSA, which was partially, but incompletely, inhibited by the PTH antagonist Nle8,18,Tyr34-bovine PTH-(3-34) amide. ACSA from murine tumor extracts has now been further purified using solvent fractionation and reverse phase HPLC. Approximately half of the ACSA is attributable to a family of three proteins (peaks IA, IB, and IC) with properties characteristic of the PTH receptor-stimulating protein extracted from rat Leydig cell and human HHM tumors. The ACSA in these three peaks of murine tumor extract elutes in the same region as human tumor ACSA on reverse phase HPLC, has a dose-response curve parallel to that of PTH, and is fully inhibited by the PTH-(3-34) antagonist in both the renal cortical and rat osteosarcoma (ROS) adenylate cyclase assays. The remaining half of the ACSA from murine tumor extracts elutes as a single peak (peak II) at a higher acetonitrile concentration on reverse phase HPLC. In the renal cortical assay, its dose-response curve differs from that of PTH, its ACSA is not affected by the PTH-(3-34) antagonist, and it potentiates PTH- or peak I- stimulated adenylate cyclase activity. In the PTH-sensitive intact cell ROS assay, peak II exhibits no ACSA. We conclude that the potent ACSA of murine tumor acid/urea extract results in large part from amplification of the PTH-specific ACSA (peak I) by peak II. Peak II is a distinct protein, not previously reported in tumor extracts, that may act as a postreceptor step in the adenylate cyclase system.




HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals
Copyright © 1986 by The Endocrine Society