title: Vertical inhibition of PI3K/Akt/mTOR signaling demonstrates in vitro and in vivo anti-fibrotic activity.
abstract: BACKGROUND
  The mammalian target of rapamycin (mTOR) regulates cellular activity in many diseases, but the complex interplay with PI3K/Akt pathway may hampers its function.
  
  
  OBJECTIVE
  This study was undertaken to determine the activity of PI3K/Akt/mTOR signaling in the fibroblasts from systemic sclerosis (SSc) patients, and compare the effects of vertical inhibiting PI3K/Akt/mTOR by BEZ235 and inhibiting mTOR alone by rapamycin in fibroblast activation and in two complementary established mouse model of SSc.
  
  
  METHODS
  Pharmaceutical specific inhibitors BEZ235 and rapamycin were used to vertical inhibit PI3K/Akt/mTOR signaling and mTOR signaling alone in cultured fibroblasts and in mice. SSc mouse model was established by daily injecting bleomycin subcutaneously or by overexpression of constitutively active type I TGF-β receptor (TβRI(ca)). To delineate the mechanisms underlying the antifibrotic effects of BEZ235 and rapamycin, activity of PI3K/Akt/mTOR signaling was analyzed by determining the expressions of phosphorylated Akt, GSK-3β, mTOR and S6 ribosomal protein (S6).
  
  
  RESULTS
  Primary dermal fibroblasts demonstrated hyperactivity of PI3K/Akt and mTOR signaling. mTOR inhibitor rapamycin failed to inhibit dermal fibrosis in an established SSc mouse model. However, administration of a dual inhibitor for PI3K/Akt and mTOR signaling BEZ235 attenuated dermal fibrosis by reversing increased dermal thickness and collagen deposition in two SSc mouse models. Furthermore, BEZ235 showed superior inhibitory effect on fibroblast activation relative to rapamycin in vitro. Also both BEZ235 and rapamycin could prevent the phosphorylation of mTOR and S6 completely. BEZ235 also blocked the activation of Akt and GSK-3β dramatically, whereas rapamycin has been shown to increase further upregulation of phosphorylated Akt on Ser473 both in vitro and in vivo.
  
  
  CONCLUSIONS
  These data show that blocking PI3K/Akt/mTOR with BEZ235 leads to superior inhibitory effect for dermal fibrosis, suggesting that vertical inhibition of PI3K/Akt/mTOR signaling may have therapeutic potential for SSc.
authors.affiliation: Division of Rheumatology, Huashan Hospital, Shanghai 200040, China; Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China.
authors.forename: Minrui
authors.initials: M
authors.lastname: Liang
authors.affiliation: Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
authors.forename: Jiaoyan
authors.initials: J
authors.lastname: Lv
authors.affiliation: Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China; Ministry of Education Key Laboratory of Contemporary Anthropology and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Chu
authors.affiliation: Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China; Ministry of Education Key Laboratory of Contemporary Anthropology and State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China.
authors.forename: Jiucun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China; Department of Neurology, Huashan Hospital, Fudan University, Shanghai 200040, China.
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Chen
authors.affiliation: Division of Rheumatology, Huashan Hospital, Shanghai 200040, China; Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Division of Rheumatology, Huashan Hospital, Shanghai 200040, China; Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xue
authors.affiliation: Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China; Department of Clinical Laboratory, Huashan Hospital, Fudan University, Shanghai 200040, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Guan
authors.affiliation: Division of Rheumatology, Huashan Hospital, Shanghai 200040, China; Institute of Rheumatology, Immunology and Allergy, Fudan University, Shanghai 200040, China. Electronic address: hjzou@fudan.edu.cn.
authors.forename: Hejian
authors.initials: H
authors.lastname: Zou
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005355:Fibrosis / Q000517:prevention & control; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors*; D011804:Quinolines / Q000494:pharmacology*; D012595:Scleroderma, Systemic / Q000188:drug therapy; D015398:Signal Transduction / Q000502:physiology*; D012867:Skin / Q000473:pathology*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D016212:Transforming Growth Factor beta / Q000494:pharmacology
chemical_list: D007093:Imidazoles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011804:Quinolines; D016212:Transforming Growth Factor beta; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; C531198:dactolisib