title: The rhPTH treatment elevates plasma secreted protein acidic and rich in cysteine levels in patients with osteoporosis.
abstract: The secreted protein acidic and rich in cysteine (SPARC), also known as osteonectin, plays an important role in osteoblast formation, maturation, and survival. Here, we report the effects of recombinant human parathyroid hormone (1-34) [rhPTH (1-34)], a bone formation-stimulating agent, and elcatonin on plasma SPARC levels in patients with osteoporosis. The rhPTH (1-34) treatment significantly increased plasma SPARC levels, and the change of plasma SPARC correlated positively with changes of lumbar bone mineral density (BMD) at L2-L4. These results unveil that SPARC may be a novel marker related to the regulation of bone formation.
  
  
  BACKGROUND
  rhPTH (1-34) is known to influence osteoclast maturation and activity through modulation of osteoblast-derived cytokines. SPARC is the most abundant noncollagenous extracellular matrix protein in the bone. So far, however, no study has reported the effects of rhPTH (1-34) administration on plasma SPARC levels in patients with osteoporosis. The purpose of this study was to compare the response of SPARC and BMD to rhPTH (1-34) and elcatonin in postmenopausal women with osteoporosis.
  
  
  METHODS
  Women were randomized to either once-daily subcutaneous injection of rhPTH (1-34) (20 μg, N = 89) or once-weekly intramuscular injection of elcatonin (200 U, N = 35) for 12 months. Plasma biochemical markers of bone turnover and BMD were measured at baseline, 6 and 12 months after treatment.
  
  
  RESULTS
  At baseline, plasma SPARC levels correlated positively with lumbar spine BMD in all patients (r = 0.45, p = 0.001). Compared with baseline, at 12 months, rhPTH (1-34) significantly increased lumbar spine BMD and plasma SPARC levels (p = 0.008 and p = 0.001, respectively), whereas elcatonin was ineffective. More importantly, the changes of plasma SPARC correlated positively with changes of lumbar BMD at L2-L4 (r = 0.47, p = 0.001) in the rhPTH (1-34)-treated group, but not in the elcatonin group.
  
  
  CONCLUSIONS
  The increase in plasma SPARC levels during the rhPTH (1-34) treatment may have contributed to the anabolic effect on bone formation, and SPARC may be a novel marker related to the regulation of bone formation.
authors.affiliation: Department of Endocrinology, the Second Affiliated Hospital, Chongqing Medical University, 400010 Chongqing, China.
authors.forename: L
authors.initials: L
authors.lastname: Zhang
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Yang
authors.forename: K
authors.initials: K
authors.lastname: Xu
authors.forename: G
authors.initials: G
authors.lastname: Boden
authors.forename: G
authors.initials: G
authors.lastname: Yang
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D016723:Bone Remodeling / Q000187:drug effects; D002116:Calcitonin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D007279:Injections, Subcutaneous; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008875:Middle Aged; D015676:Osteonectin; D015663:Osteoporosis, Postmenopausal / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D019379:Teriparatide / Q000008:administration & dosage / Q000627:therapeutic use*; D016896:Treatment Outcome; D025521:Tumor Suppressor Proteins / Q000097:blood*
chemical_list: D015415:Biomarkers; D050071:Bone Density Conservation Agents; D015676:Osteonectin; C577241:SPARC protein, human; D025521:Tumor Suppressor Proteins; D019379:Teriparatide; D002116:Calcitonin; C012755:elcatonin