title: Rapamycin inhibits transforming growth factor beta 1 induced myofibroblast differentiation via the phosphorylated-phosphatidylinositol 3-kinase mammalian target of rapamycin signal pathways in nasal polyp-derived fibroblasts.
abstract: OBJECTIVE
  Rapamycin has antiproliferative and antifibrogenic effects in vitro and in vivo. The purpose of this study was to evaluate the effects of rapamycin on transforming growth factor (TGF) beta 1 induced myofibroblast differentiation (alpha smooth-muscle actin [SMA]), extracellular matrix production, and collagen contraction in nasal polyp-derived fibroblasts (NPDF). The underlying molecular mechanisms of rapamycin were also determined in NPDFs.
  
  
  METHODS
  NPDFs were grown in culture and transformed into myofibroblasts by using TGF beta 1 (5 ng/mL). For cytotoxicity evaluation, a 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl-tetrazolium bromide assay was used. Expression levels of alpha SMA, phosphorylated phosphatidylinositol 3-kinase (PI3K), and phosphorylated mammalian target of rapamycin (mTOR) were determined by using Western blot, reverse transcription-polymerase chain reaction, and immunofluorescence staining. The total amount of collagen was analyzed by using the Sircol collagen assay, and contractile activity was measured with a collagen gel contraction assay. Silencing mTOR with mTOR-specific small interference RNA was determined by using reverse transcription-polymerase chain reaction.
  
  
  RESULTS
  Whereas rapamycin (range, 0-400 nM) had no significant cytotoxic effects on TGF beta 1 induced NPDFs, it significantly reduced the expression levels of alpha-SMA in TGF beta 1 induced NPDFs in a dose-dependent manner. TGF beta 1 induced collagen production and collagen contraction were significantly inhibited by rapamycin treatment. Rapamycin also attenuated the TGF beta 1 induced activation of PI3K and mTOR, and its inhibitory effects were similar to those of mTOR silencing and a specific PI3K inhibitor.
  
  
  CONCLUSIONS
  Rapamycin inhibited TGF beta 1 induced myofibroblast differentiation, extracellular matrix production, and collagen contraction through the PI3K/mTOR signal pathways in NPDFs.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, South Korea This study was support.
authors.forename: Dong-Yn
authors.initials: DY
authors.lastname: Ko
authors.forename: Jae-Min
authors.initials: JM
authors.lastname: Shin
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Um
authors.forename: Byungjin
authors.initials: B
authors.lastname: Kang
authors.forename: Il-Ho
authors.initials: IH
authors.lastname: Park
authors.forename: Heung-Man
authors.initials: HM
authors.lastname: Lee
mesh_terms: D000199:Actins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D058628:Myofibroblasts / Q000187:drug effects* / Q000502:physiology; D009298:Nasal Polyps / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D007166:Immunosuppressive Agents; D034741:RNA, Small Interfering; D016212:Transforming Growth Factor beta; D003094:Collagen; C546842:MTOR protein, human; D058539:Phosphatidylinositol 3-Kinase; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus