title: Folic acid inhibits dedifferentiation of PDGF-BB-induced vascular smooth muscle cells by suppressing mTOR/P70S6K signaling.
abstract: OBJECTIVE
  Folic acid (FA) supplementation reduces the risk of atherosclerosis and stroke. Phenotypic change from differentiated to dedifferentiated vascular smooth muscle cells (VSMCs) plays an important role in atherosclerosis development; however, the exact mechanisms remain unknown. This study aimed to assess whether FA through mammalian target of rapamycin (mTOR)/P70S6K signaling inhibits platelet derived growth factor (PDGF-BB) induced VSMC dedifferentiation.
  
  
  METHODS
  VSMCs from primary cultures were identified by morphological observation and α-smooth muscle actin (α-SM-actin, α-SMA) immunocytochemistry. Then, VSMCs were induced by PDGF-BB and treated with varying FA concentrations. Rapamycin and MHY-1485 were used to inhibit or activate the mTOR/P70S6K pathway, respectively. Next, MTT, Transwell, and wound healing assays were employed to assess proliferation and migration of VSMCs. In addition, Western blotting was used to evaluate protein levels of α-SMA, calponin, osteopontin, mTOR, p-mTOR, P70S6K and p-P70S6K in VSMCs.
  
  
  RESULTS
  VSMCs showed phenotypic alteration from differentiated to dedifferentiated cells in response to PDGF-BB. MTT, Transwell and wound healing assays showed that FA markedly inhibited proliferation and migration in PDGF-BB-induced VSMCs, in a time and concentration-dependent manner. FA treatment increased the expression levels of the contractile phenotype marker proteins α-SMA and calponin compared with VSMCs stimulated by PDGF-BB alone. Furthermore, FA significantly suppressed mTOR and P70S6K phosphorylation compared with PDGF-BB alone. Similar to FA, downregulation of mTOR signaling by rapamycin inhibited VSMC dedifferentiation. In contrast, upregulation of mTOR signaling by MHY-1485 reversed the FA-induced inhibition of VSMC dedifferentiation.
  
  
  CONCLUSIONS
  Folic acid inhibits dedifferentiation of PDGF-BB-induced VSMCs by suppressing mTOR/P70S6K signaling.
authors.affiliation: The First Clinical Medical College, Wenzhou Medical University Wenzhou 325000, Zhejiang, China.
authors.forename: Sunlei
authors.initials: S
authors.lastname: Pan
authors.affiliation: The First Clinical Medical College, Wenzhou Medical University Wenzhou 325000, Zhejiang, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Lin
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Hangqi
authors.initials: H
authors.lastname: Luo
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Feidan
authors.initials: F
authors.lastname: Gao
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Meng
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Changzuan
authors.initials: C
authors.lastname: Zhou
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Chengjian
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang University Shaoxing 312000, Zhejiang, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Ji
authors.affiliation: The First Clinical Medical College, Wenzhou Medical UniversityWenzhou 325000, Zhejiang, China; Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang UniversityShaoxing 312000, Zhejiang, China.
authors.forename: Jufang
authors.initials: J
authors.lastname: Chi
authors.affiliation: The First Clinical Medical College, Wenzhou Medical UniversityWenzhou 325000, Zhejiang, China; Department of Cardiology, Shaoxing People's Hospital, Shaoxing Hospital of Zhejiang UniversityShaoxing 312000, Zhejiang, China.
authors.forename: Hangyuan
authors.initials: H
authors.lastname: Guo
keywords: Vascular smooth muscle cells; dedifferentiation; folic acid; mTOR/P70S6K signaling pathway