Paricalcitol versus cinacalcet plus low-dose vitamin D for the treatment of secondary hyperparathyroidism in patients receiving haemodialysis: study design and baseline characteristics of the IMPACT SHPT study

Background. Paricalcitol and cinacalcet are common therapies for patients on haemodialysis with secondary hyperparathyroidism (SHPT). We conducted a multi-centre study in 12 countries to compare the safety and efficacy of paricalcitol and cinacalcet for the treatment of SHPT

Transforming growth factor-[beta]1 regulates steady-state PTH/PTHrP receptor mRNA levels and PTHrP binding in ROS 17/2.8 osteosarcoma cells

The effect of transforming growth factor [beta]1 (TGF-[beta]1) on the expression of mRNA for the parathyroid hormone receptor and binding of iodinated parathyroid hormone-related protein in ROS 17/2.8 osteosarcoma cells was evaluated. TGF-[beta]1 stimulated a 2-7-fold increase in steady state mRNA levels for the parathyroid hormone receptor at a maximal dose of 5 ng/ml, with increased levels of expression at 6 h of TGF-[beta]1-incubation, and peak levels at 8-24 h. Receptor binding studies revealed a significant increase in PTHrP-specific binding with TGF-[beta]1 doses as low as 0.5 ng/ml and a 55% increase in numbers of receptors with no alteration in binding affinity with 5.0 ng/ml TGF-[beta]1. Time course studies indicated that receptor binding was increased at 24 h with peak levels reached at 48 h of treatment. PTH-stimulated cAMP levels were significantly increased in ROS 17/2.8 cells treated with TGF-[beta]1 (0.5 ng/ml) for 48 h. These data indicate that TGF-[beta]1 upregulates steady-state mRNA, ligand binding and PTH/PTHrP receptor signaling in rat osteosarcoma cells. The effects of TGF-[beta]1 on bone may be attributed in part to regulation of the PTH/PTHrP receptor at the molecular level.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31617/1/0000549.pd

PTHrP Induces Autocrine/Paracrine Proliferation of Bone Tumor Cells through Inhibition of Apoptosis

Giant Cell Tumor of Bone (GCT) is an aggressive skeletal tumor characterized by local bone destruction, high recurrence rates and metastatic potential. Previous work in our lab has shown that the neoplastic cell of GCT is a proliferating pre-osteoblastic stromal cell in which the transcription factor Runx2 plays a role in regulating protein expression. One of the proteins expressed by these cells is parathryroid hormone-related protein (PTHrP). The objectives of this study were to determine the role played by PTHrP in GCT of bone with a focus on cell proliferation and apoptosis. Primary stromal cell cultures from 5 patients with GCT of bone and one lung metastsis were used for cell-based experiments. Control cell lines included a renal cell carcinoma (RCC) cell line and a human fetal osteoblast cell line. Cells were exposed to optimized concentrations of a PTHrP neutralizing antibody and were analyzed with the use of cell proliferation and apoptosis assays including mitochondrial dehydrogenase assays, crystal violet assays, APO-1 ELISAs, caspase activity assays, flow cytometry and immunofluorescent immunohistochemistry. Neutralization of PTHrP in the cell environment inhibited cell proliferation in a consistent manner and induced apoptosis in the GCT stromal cells, with the exception of those obtained from a lung metastasis. Cell cycle progression was not significantly affected by PTHrP neutralization. These findings indicate that PTHrP plays an autocrine/paracrine neoplastic role in GCT by allowing the proliferating stromal cells to evade apoptosis, possibly through non-traditional caspase-independent pathways. Thus PTHrP neutralizing immunotherapy is an intriguing potential therapeutic strategy for this tumor

Fibroblast growth factor 23 is associated with proteinuria and smoking in chronic kidney disease: An analysis of the MASTERPLAN cohort

Contains fulltext : 107913.pdf (postprint version ) (Open Access)BACKGROUND: Fibroblast growth factor 23 (FGF23) has emerged as a risk factor for cardiovascular disease and mortality throughout all stages of chronic kidney disease (CKD), independent from established risk factors and markers of mineral homeostasis. The relation of FGF23 with other renal and non-renal cardiovascular risk factors is not well established. METHODS: Using stored samples, plasma FGF23 was determined in 604 patients with moderate to severe kidney disease that participated in the MASTERPLAN study (ISRCTN73187232). The association of FGF23 with demographic and clinical parameters was evaluated using multivariable regression models. RESULTS: Mean age in the study population was 60 years and eGFR was 37 (+/- 14) ml/min/1.73 m(2). Median proteinuria was 0.3 g/24 hours [IQR 0.1-0.9]. FGF23 level was 116 RU/ml [67-203] median and IQR. Using multivariable analysis the natural logarithm of FGF23 was positively associated with history of cardiovascular disease (B = 0.224 RU/ml; p = 0.002), presence of diabetes (B = 0.159 RU/ml; p = 0.035), smoking (B = 0.313 RU/ml; p < 0.001), phosphate level (B = 0.297 per mmol/l; p = 0.0024), lnPTH (B = 0.244 per pmol/l; p < 0.001) and proteinuria (B = 0.064 per gram/24 hrs; p = 0.002) and negatively associated with eGFR (B = -0.022 per ml/min/1.73 m(2); p < 0.001). CONCLUSIONS: Our study demonstrates that in patients with CKD, FGF23 is related to proteinuria and smoking. We confirm the relation between FGF23 and other cardiovascular risk factors

Erythroid Promoter Confines FGF2 Expression to the Marrow after Hematopoietic Stem Cell Gene Therapy and Leads to Enhanced Endosteal Bone Formation

Fibroblast growth factor-2 (FGF2) has been demonstrated to be a promising osteogenic factor for treating osteoporosis. Our earlier study shows that transplantation of mouse Sca-1+ hematopoietic stem/progenitor cells that are engineered to express a modified FGF2 leads to considerable endosteal/trabecular bone formation, but it also induces adverse effects like hypocalemia and osteomalacia. Here we report that the use of an erythroid specific promoter, β-globin, leads to a 5-fold decrease in the ratio of serum FGF2 to the FGF2 expression in the marrow cavity when compared to the use of a ubiquitous promoter spleen focus-forming virus (SFFV). The confined FGF2 expression promotes considerable trabeculae bone formation in endosteum and does not yield anemia and osteomalacia. The avoidance of anemia in the mice that received Sca1+ cells transduced with FGF2 driven by the β-globin promoter is likely due to attenuation of high-level serum FGF2-mediated stem cell mobilization observed in the SFFV-FGF2 animals. The prevention of osteomalacia is associated with substantially reduced serum Fgf23/hypophosphatemia, and less pronounced secondary hyperparathyroidism. Our improved stem cell gene therapy strategy represents one step closer to FGF2-based clinical therapy for systemic skeletal augmentation

A novel parathyroid hormone (PTH)/PTH-related peptide receptor mutation in Jansen's metaphyseal chondrodysplasia

Journal of Clinical Endocrinology and Metabolism8493052-3057JCEM