Differential regulation of cadherin expression by osteotropic hormones and growth factors in vitro in human osteoprogenitor cells.
OBJECTIVE
To examine if cadherins are expressed constitutively in human bone marrow stromal cells (hBMSC) and investigate the regulation of cadherin expression by various osteotropic hormones and local factors.


METHODS
Cadherin expression was examined in first passaged (secondary) hBMSC as well as in the conditionally-immortalized human osteoprogenitor cell line (hOP-7). Using a monoclonal antibody (MoAb C-1821) to a cytoplasmic domain common to all known cadherins (pan-cadherin MoAb), cadherins were immunolocalized in first passaged hBMSC as well as in hOP-7 cells. In addition, intense immunostaining for cadherin expression was associated with alkaline phosphatase (ALP) in nodules formed in the high density cultures of hOP-7 cells. Human E-cadherin (HECD) was specifically detected by Western blotting in extracts of untreated hBMSC using an anti-HECD MoAb 004FD.


RESULTS
Differential regulation of cadherin expression by various osteotropic hormones and local factors (parathyroid hormone, dexamethasone, estradiol, prostaglandin E2, basic fibroblast growth factor, and tumor necrosis factor-beta) was also observed. In addition, blocking cadherins with the MoAb C-1821 increased basal ALP activity and had an additive effect on 1, 25(OH) 2D3-induced ALP activity.


CONCLUSIONS
Cadherins are expressed in human osteoprogenitor cells and are involved in the osteogenic differentiation. The differential modulation of cadherin expression by osteotropic agents indicates that these agents may regulate osteoprogenitor cells through different cadherins and these cadherins may play different roles.
Liu
Peng
P
Arthritis Clinic and Research Center, People's Hospital, Medical Health Center, Peking University, Beijing 100044, China.
Lin
Jian-hao
JH
Zhang
Bi
B
D000469:Alkaline Phosphatase / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects*; D015820:Cadherins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006801:Humans; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D015820:Cadherins; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D003907:Dexamethasone; D000469:Alkaline Phosphatase; D002117:Calcitriol; D015232:Dinoprostone