title: Rapamycin inhibits human adipocyte differentiation in primary culture.
abstract: OBJECTIVE
  The immunosuppressant drug rapamycin, has been reported to inhibit 3T3-L1 adipocyte differentiation by interfering with critical postconfluent mitoses that are required early on for successful differentiation of this cell line (clonal expansion phase). In contrast to the murine 3T3-L1 preadipocyte cell line, human preadipocytes in primary culture do not undergo clonal expansion during differentiation. We investigated whether rapamycin could inhibit human adipocyte differentiation.
  
  
  METHODS
  The effect of rapamycin on the induction of differentiation of human preadipocytes in primary culture into adipocytes was measured using Oil Red O staining and glycerol phosphate dehydrogenase activity.
  
  
  RESULTS
  We have observed that rapamycin severely curtails human adipocyte differentiation of both omental and abdominal subcutaneous preadipocytes (to 14% and 19% of standard differentiation, respectively). The rapamycin-mediated inhibition of human adipocyte differentiation could be reversed in the presence of excess amounts of FK-506, which displaces rapamycin from its intracellular receptor, FKPB12. Measurement of cytosolic protein and [3H]thymidine incorporation into DNA confirmed the absence of proliferation during differentiation of human preadipocytes in primary culture.
  
  
  CONCLUSIONS
  Our data indicate that rapamycin exerts important negative regulatory effects on adipogenesis in human preadipocytes, through a mechanism that does not depend on interruption of clonal expansion.
authors.affiliation: Department of Medicine, Loeb Health Research Institute, Ottawa Hospital, University of Ottawa, Ontario, Canada.
authors.forename: A
authors.initials: A
authors.lastname: Bell
authors.forename: L
authors.initials: L
authors.lastname: Grunder
authors.forename: A
authors.initials: A
authors.lastname: Sorisky
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000187:drug effects*; D000273:Adipose Tissue / Q000166:cytology*; D001391:Azo Compounds / Q000737:chemistry; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D004396:Coloring Agents / Q000737:chemistry; D005260:Female; D005993:Glycerolphosphate Dehydrogenase / Q000032:analysis; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D012588:Scintillation Counting; D020123:Sirolimus / Q000494:pharmacology*; D013936:Thymidine / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D007166:Immunosuppressive Agents; D005993:Glycerolphosphate Dehydrogenase; C011049:oil red O; D013936:Thymidine; D020123:Sirolimus