title: Nicotinamide treatment in a murine model of familial tumoral calcinosis reduces serum Fgf23 and raises heart calcium.
abstract: Mutations in the GALNT3 gene result in familial tumoral calcinosis, characterized by persistent hyperphosphatemia and ectopic calcific masses in soft tissues. Since calcific masses often recur after surgical removal, a more permanent solution to the problem is required. Nicotinamide is reported to lower serum phosphate by decreasing sodium-dependent phosphate co-transporters in the gut and kidney. However, its effectiveness in tumoral calcinosis remains unknown. In this study, we investigated nicotinamide as a potential therapy for tumoral calcinosis, using a murine model of the disease-Galnt3 knockout mice. Initially, five different doses of nicotinamide were given to normal heterozygous mice intraperitoneally or orally. Treatment had no effect on serum phosphate levels, but serum levels of a phosphaturic hormone, fibroblast growth factor 23 (Fgf23), decreased in a dose-dependent manner. Subsequently, high-dose nicotinamide (40mM) was tested in Galnt3 knockout mice fed a high phosphate diet. The radiographic data pre- and post-treatment showed that nicotinamide did not reverse the calcification. However, the treatment retarded calcification growth after 4weeks, while in the untreated animals, calcifications increased in size. The therapy did not affect serum phosphate levels, but intact Fgf23 decreased in the treated mice. The treated mice also had increased calcium in the heart. In summary, nicotinamide did not alter serum phosphate levels, likely due to compensatory decrease in Fgf23 to counteract the phosphate lowering effect of nicotinamide. Although increased calcium accumulation in the heart is a concern, the therapy appears to slow down the progression of ectopic calcifications.
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Austin M
authors.initials: AM
authors.lastname: Reilly
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors.forename: Amie K
authors.initials: AK
authors.lastname: Gray
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA; Roudebush Veteran Administration Medical Center, Indianapolis, IN 46202, USA.
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Moe
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA. Electronic address: ichikawa@iu.edu.
authors.forename: Shoji
authors.initials: S
authors.lastname: Ichikawa
mesh_terms: D000818:Animals; D002114:Calcinosis / Q000097:blood* / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors / Q000097:blood*; D008297:Male; D051379:Mice; D017350:N-Acetylgalactosaminyltransferases / Q000235:genetics; D009536:Niacinamide / Q000627:therapeutic use*; D000097763:Polypeptide N-acetylgalactosaminyltransferase
chemical_list: D002118:Calcium; D000089703:Fibroblast Growth Factor-23; D005346:Fibroblast Growth Factors; D017350:N-Acetylgalactosaminyltransferases; D009536:Niacinamide; D000097763:Polypeptide N-acetylgalactosaminyltransferase; C000717428:Fgf23 protein, mouse
keywords: Calcification; Fgf23; Nicotinamide; Phosphate; Tumoral calcinosis