title: Roxithromycin treatment inhibits TGF-β1-induced activation of ERK and AKT and down-regulation of caveolin-1 in rat airway smooth muscle cells.
abstract: BACKGROUND
  Roxithromycin (RXM) has been widely used in asthma treatment; however, the mechanism has not been fully understood. The aim of our study was to investigate the underlying mechanism of RXM treatment in mediating the effect of transforming growth factor (TGF)-β1 on airway smooth muscle cells (ASMCs) proliferation and caveolinn-1 expression.
  
  
  METHODS
  Firstly, the rat ovalbumin (OVA) model was built according to the previous papers. Rat ASMCs were prepared and cultured, and then TGF-β1 production in ASMCs was measured by enzyme-linked immunosorbent assay (ELISA). Moreover, the proliferation of ASMCs was determined using cell counting kit (CCK-8) assay. Additionally, the expressions of caveolin-1, phosphorylated-ERK1/2 (p-ERK1/2) and phosphorylated-AKT (p-AKT) in ASMCs treated with or without PD98059 (an ERK1/2 inhibitor), wortannin (a PI3K inhibitor), β-cyclodextrin (β-CD) and RXM were measured by Western blot. Finally, data were evaluated using t-test or one-way ANOVA, and then a P value < 0.05 was set as a threshold.
  
  
  RESULTS
  Compared with normal control, TGF-β1 secretion was significantly increased in asthmatic ASMCs; meanwhile, TGF-β1 promoted ASMCs proliferation (P < 0.05). However, ASMCs proliferation was remarkably inhibited by RXM, β-CD, PD98059 and wortmannin (P < 0.05). Moreover, the expressions of p-ERK1/2 and p-AKT were increased and peaked at 20 min after TGF-β1 stimulation, and then suppressed by RXM. Further, caveolin-1 level was down-regulated by TGF-β1 and up-regulated by inhibitors and RXM.
  
  
  CONCLUSIONS
  Our findings demonstrate that RXM treatment inhibits TGF-β1-induced activation of ERK and AKT and down-regulation of caveolin-1, which may be the potential mechanism of RXM protection from chronic inflammatory diseases, including bronchial asthma.
authors.forename: Yuanrong
authors.initials: Y
authors.lastname: Dai
authors.forename: Fengqin
authors.initials: F
authors.lastname: Li
authors.forename: Liqin
authors.initials: L
authors.lastname: Wu
authors.forename: Ruili
authors.initials: R
authors.lastname: Wang
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Sunshun
authors.initials: S
authors.lastname: Yan
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.forename: Mengling
authors.initials: M
authors.lastname: Xia
authors.forename: Chunxue
authors.initials: C
authors.lastname: Bai
mesh_terms: D000818:Animals; D051242:Caveolin 1 / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020545:Respiratory Mucosa / Q000187:drug effects / Q000378:metabolism; D015575:Roxithromycin / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016896:Treatment Outcome
chemical_list: D051242:Caveolin 1; D053773:Transforming Growth Factor beta1; D015575:Roxithromycin; D051057:Proto-Oncogene Proteins c-akt
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