Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0005940 (bone disease)
 7,459 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays key roles in extracellular calcium ion (Ca(2+)(o)) homeostasis by enabling parathyroid, kidney, and other cells to directly "sense" changes in Ca(2+)(o). In multiple myeloma-associated bone disease, myeloma cells could raise the level of Ca(2+)(o) within their immediate vicinity in the bone marrow microenvironment, through their known capacity to cause bone destruction by stimulating osteoclastic bone resorption. Thus if myeloma cells expressed the CaR, they might sense these locally elevated levels of Ca(2+)(o), which could, in turn, potentially modify their function(s) in ways that could contribute to myeloma bone disease or other aspects of the pathophysiology of this disabling hematological malignancy. In this study, we examined the expression of the CaR in three myeloma cell lines, human U266, IM-9, and RPMI8226 cells. CaR protein was present in all three cell lines as assessed by immunocytochemistry and Western blot analysis using a monoclonal antibody specific for the CaR. Moreover, the use of reverse transcription-polymerase chain reaction (RT-PCR) with CaR-specific primers, followed by nucleotide sequencing of the amplified products, also identified CaR transcripts in the three cell lines. Exposure to known polycationic agonists of the CaR, including high Ca(2+)(o) (2.5mM), neomycin, and gadolinium (Gd(3+)) as well as a specific CaR activator, NPS R467, augmented cell proliferation in all three cell lines. RT-PCR revealed that U266 cells, but not IM-9 cells or RPMI8226 cells, expressed interleukin-6 (IL-6), the expression of which was not enhanced by treatments with CaR agonists. Therefore, taken together, our data first document the fact that the myeloma cell lines, U266, IM-9, and RPMI8226, all express CaR protein and mRNA. Moreover, the CaR expressed on myeloma cells could sense the locally high levels of Ca(2+)(o) in the vicinity of sites of osteoclastic bone resorption and stimulate their proliferation in an IL-6-independent manner. These processes may result in promoting further growth of the tumor and aggravating the associated bone disease.
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PMID:The extracellular calcium Ca2+o-sensing receptor is expressed in myeloma cells and modulates cell proliferation. 1245 70

Cinacalcet [AMG 073, KRN 1493, NPS 1493] is an orally active, second-generation calcimimetic compound licensed by NPS Pharmaceuticals to Amgen in the US for potential treatment of hyperparathyroidism (HPT). Cinacalcet modulates (increases the sensitivity of) calcium receptors on the surface of parathyroid cells thereby inhibiting the oversecretion of parathyroid hormone, which characterises HPT. It also represents a potentially significant advance for chronic kidney disease patients diagnosed with secondary HPT, a common yet serious metabolic disorder where parathyroid hormone levels are elevated. Patients with this disease can suffer from bone disease, bone pain and fractures, soft tissue calcification, vascular calcification and cardiovascular complications. Amgen has rights to develop and sell cinacalcet throughout the world except in Japan, Taiwan and China, where the compound was licensed to Kirin Brewery. Kirin is developing it as KRN 1493 in phase II clinical studies in Japan. In December 2001, commencement of a phase III clinical trial with cinacalcet for the treatment of secondary HPT, triggered a 3 million US dollars milestone payment to NPS Pharmaceuticals. In September 2003, submission of an NDA to the US FDA for cinacalcet for secondary HPT will be followed by a milestone payment of 6 million US dollars to NPS. NPS, Kirin and Amgen were also developing another compound, tecalcet, for HPT, but that project has been discontinued in favour of cinacalcet. In September 2003, Amgen submitted an NDA to the US FDA for secondary HPT in patients with chronic kidney disease. In April 2003, Amgen announced positive results from a phase III clinical trial with cinacalcet in patients with secondary HPT. In a clinical study in patients on dialysis suffering from the effects of chronically elevated levels parathyroid hormone, cinacalcet appeared to be safe and well tolerated and was significantly more effective than placebo. Two more additional efficacy studies with cinacalcet have also been completed. Phase II trials of cinacalcet in dialysis patients with secondary HPT and in patients with primary HPT were successfully completed.
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PMID:Cinacalcet: AMG 073, Calcimimetics--Amgen/NPS Pharmaceuticals, KRN 1493, NPS 1493. 1458 63

The recent introduction of calcimimetics, a novel class of therapeutic agents, has led to a change in the treatment strategy of secondary hyperparathyroidism in patients with end-stage renal disease. In initial acute studies in chronic hemodialysis patients, the calcimimetic cinacalcet was shown to reduce plasma intact parathyroid hormone within hours, followed by a rapid, profound decrease in plasma calcium and a minor decrease in plasma phosphorus. Subsequent reports showed that the long-term administration of cinacalcet to such patients proved to be superior to standard therapy in controlling secondary uremic hyperparathyroidism, in that it was able to induce a decrease in both plasma intact parathyroid hormone and the calcium x phosphorus product, in contrast to the effects of active vitamin D sterols. This allowed the achievement of the guideline treatment targets proposed by the National Kidney Foundation Kidney Disease Outcomes Quality Initiative in a much larger proportion of dialysis patients than standard therapy did. Moreover, the effect of cinacalcet is long-lasting. An important question is that of cinacalcet's effects on patient outcomes, which is still lacking. A similar lack of information exists for most other treatment modalities given to correct the mineral and bone disorder of chronic kidney disease. A post-hoc analysis of four clinical trials combined done in hemodialysis patients showed that randomization to cinacalcet led to significant reductions in the risk of parathyroidectomy, fracture, and cardiovascular hospitalization. To obtain a definitive answer to this question, including patient survival, we will have to wait for the results of prospective, randomized controlled trials. In pre-clinical studies performed in rats with chronic renal failure, the administration of the calcimimetic NPS R-568 at the time of uremia induction allowed the prevention of parathyroid hyperplasia, and the reversal of already established hyperplasia as well. Perhaps more important from the clinical point of view, NPS R-568 also appeared to allow reversal of osteitis fibrosa in uremic rats and reduction of aortic calcification and atherosclerosis in uremic rats and mice. In conclusion, the clinical introduction of cinacalcet allows for better control of secondary hyperparathyroidism in dialysis patients as compared to standard therapy, based on surrogate biochemical markers. Hopefully, in the future, this improvement will be shown to be associated with better patient outcomes for the treatment of fractures and cardiovascular morbidity and mortality.
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PMID:Cinacalcet treatment in dialysis patients with secondary hyperparathyroidism: effects and open issues. 1903 22