Adenylate cyclase-stimulating, bone-resorbing and B TGF-like activities in canine apocrine cell adenocarcinoma of the anal sac

Ascites sarcoma 180, a tumor associated with hypercalcemia, secretes potent bone-resorbing factors including transforming growth factor alpha, interleukin-1 alpha and interleukin-6

Ascites sarcoma 180 (S180A) is a transplantable tumor which causes hypercalcemia in tumor-bearing mice, and stimulates bone resorption without parathyroid hormone-like activity. In the present study, parathyroid hormone-related protein (PTHrP) mRNA could not be detected in total RNA from S180A cells. Bone-resorbing activity (BRA) derived from serum-free conditioned medium of S180A cells (S180A-CM) was coeluted with either transforming growth factor alpha (TGF alpha) activity (peak A, approximate M(r), 29 kDa) or lymphocyte-activating factor (LAF) activity (peak B, M(r), 20.1-24 kDa) in Bio-Gel P-100 column chromatography. Fractions in peak A and B contained IL-6 but not tumor necrosis factor alpha (TNF alpha). Subsequent separation of peak A by reverse-phase high performance liquid chromatography produced a single fraction which contained both BRA and TGF alpha activity. Recombinant human TGF alpha-induced bone resorption was completely inhibited by indomethacin. The BRA in peak A was partially inhibited by indomethacin and almost completely inhibited by simultaneous treatment of indomethacin and anti-IL-6 antibody. The BRA in peak B was partially inhibited by neutralization with anti-IL-1 alpha antibody and was completely inhibited by simultaneous treatment with anti-IL-1 alpha and anti-IL-6 antibody in the absence of indomethacin. Bone resorption induced by S180A-CM was associated with an increased production of prostaglandin E2 (PGE2) by calvaria. The BRA in S180A-CM, however, was not completely abolished by the simultaneous addition of indomethacin and anti-IL-1 alpha, anti-IL-1 beta and anti-IL-6 antibodies. Our findings indicate that (1) BRA derived from S180A cells includes TGF alpha, IL-1 alpha, IL-6 and some other unknown factor(s), distinct from PTHrP, IL-1 beta and TNF alpha, and (2) these unknown factors resorb bone in part via a PGE2-independent pathway.

Ascites sarcoma 180, an animal model of humoral hypercalcemia of malignancy, produces a factor(s) exhibiting potent bone-resorbing activity without any parathyroid hormone-like activity

Ascites sarcoma 180 (S180A) is a transplantable tumor maintained in ddY mice. In the tumor-bearing mice, the plasma Ca, Pi and acid phosphatase levels increased and the plasma alkaline phosphatase levels decreased. The elevation of plasma Pi levels is unusual in humoral hypercalcemia of malignancy (HHM). To characterize the pathogenesis of HHM in the animals, the biological activities in the serum-free conditioned media (CM) of S180A cell cultures were examined. The S180A CM stimulated bone resorption dose dependently and showed TGF-like, IL-1-like and mitogenic activity. Unlike parathyroid hormone (PTH), the factor(s) failed to stimulate cAMP production by either UMR 106-01 cells or neonatal mouse calvaria at concentrations that stimulate bone resorption. Also, the factor(s) stimulated proliferation of UMR 106-01 cells concomitant with a slight increase in intracellular calcium levels. These results indicate that S180A cells produce a factor(s) responsible for bone resorption which is apparently different from PTH-like activity.