Parathyroid hormone-related protein in the aetiology of fibrous dysplasia of bone in the McCune Albright syndrome.
OBJECTIVE
Fibrous dysplasia, observed in bone lesions in the McCune Albright syndrome (MAS), is thought to result from abnormalities in cells of the osteogenic lineage associated with over-activation of the cAMP signalling pathway in affected cells. The aim of this study was to investigate the role of parathyroid hormone-related protein (PTHrP) in the aetiology of MAS, and to determine a possible therapeutic role for 1,25-dihydroxy vitamin D(3) (1,25(OH)(2)D(3)).


METHODS
The effects of 1,25(OH)(2)D(3) on PTHrP production and mRNA expression were determined in vitro. 1,25(OH)(2)D(3) therapy was administered to three patients with MAS.


METHODS
Clinical data from four MAS patients (MAS1, 2, 3 and 4), and in vitro studies using bone from three MAS patients (MAS1, 2, and 3), are presented.


METHODS
Immunoradiometric assay and low-cycle number reverse transcriptase-linked PCR were used to determine PTHrP production and mRNA expression in vitro. Standard clinical biochemistry was recorded pre and post commencement of 1,25(OH)(2)D(3) treatment.


RESULTS
We report the elevated secretion of PTHrP, and a concomitant rise in PTHrP mRNA expression, in cultured osteoblasts from three MAS patients. Treatment with 1,25(OH)(2)D(3) produced a dose-dependent decrease in PTHrP protein secretion and mRNA expression. Marked improvement in bone biochemistry in MAS1, 2 and 3 post treatment with 1,25(OH)(2)D(3) is documented.


CONCLUSIONS
This study provides the first evidence suggesting that PTHrP may contribute to the aetiology of fibrous dysplasia in MAS. In addition, the therapeutic administration of 1,25(OH)92)D(3) may provide clinicians with an important new regime for symptomatic relief of bone pain and fracture in some patients with MAS.
Fraser
W D
WD
University Department of Clinical Chemistry, Royal Liverpool University Hospital, UK.
Walsh
C A
CA
Birch
M A
MA
Durham
B
B
Dillon
J P
JP
McCreavy
D
D
Gallagher
J A
JA
D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D005359:Fibrous Dysplasia, Polyostotic / Q000188:drug therapy / Q000209:etiology* / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D015592:Immunoradiometric Assay; D008297:Male; D010006:Osteoblasts / Q000502:physiology; D010281:Parathyroid Hormone / Q000502:physiology*; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013250:Steroid Hydroxylases / Q000627:therapeutic use
C000715470:MAS1 protein, human; D010281:Parathyroid Hormone; D000090063:Proto-Oncogene Mas; D012333:RNA, Messenger; D013250:Steroid Hydroxylases; C406322:vitamin D 1-alpha hydroxylase