Astragaloside IV inhibits platelet-derived growth factor-BB-stimulated proliferation and migration of vascular smooth muscle cells via the inhibition of p38 MAPK signaling

Abstract

Astragaloside IV (AS-IV), the major active component extracted from Astragalus membranaceus, has been demonstrated to exhibit protective effects on the cardiovascular, immune, digestive and nervous systems; thus, has been widely used in traditional Chinese medicine. Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) is closely associated with the initiation and progression of cardiovascular diseases, including atherosclerosis and restenosis. However, the effects of AS-IV on VSMCs remain unknown. For the first time, the present study demonstrated that AS-IV markedly suppressed platelet-derived growth factor (PDGF)-BB-stimulated cellular proliferation and migration of HDMEC-a human dermal VSMCs (HDVSMCs). Further investigation into the underlying molecular mechanisms demonstrated that the administration of AS-IV attenuated the PDGF-BB-stimulated switch of HDVSMCs into a proliferative phenotype. Furthermore, AS-IV inhibited the PDGF-BB-induced expression of cell cycle-associated proteins, as well as the upregulation of matrix metalloproteinase (MMP)2, but not MMP9. In addition, AS-IV was shown to downregulate the activation of p38 mitogen-activated protein kinase (MAPK) signaling induced by PDGF-BB in HDVSMCs. Therefore, the observations of the present study indicate that AS-IV inhibits PDGF-BB-stimulated VSMC proliferation and migration, possibly by inhibiting the activation of the p38 MAPK signaling pathway. Thus, AS-IV may be useful for the treatment of vascular diseases.

Keywords: astragaloside IV; migration; platelet-derived growth factor; proliferation; vascular smooth muscle cell.

Figure 1

AS-IV inhibited PDGF-BB-induced HDVSMC proliferation. MTT assays were performed to determine the rate of HDVSMC proliferation in each group. Control, HDVSMCs without any treatment; PDGF-BB, HDVSMCs treated with PDGF-BB; PDGF-BB + AS-IV, HDVSMCs treated with PDGF-BB and AS-IV; AS-IV, astragaloside IV; PDGF, platelet-derived growth factor; HDVSMC, human dermal vascular smooth muscle cell.

Figure 2

AS-IV suppressed PDGF-BB-induced upregulation of cell cycle-associated proteins in HDVSMCs. Western blot analysis was performed to determine the expression levels of cell cycle-associated proteins in each group. GAPDH was used as an internal reference. ^**P<0.01. Control, HDVSMCs without any treatment; PDGF-BB, HDVSMCs treated with PDGF-BB; PDGF-BB + AS-IV, HDVSMCs treated with PDGF-BB and AS-IV; AS-IV, astragaloside IV; PDGF, platelet-derived growth factor; HDVSMC, human dermal vascular smooth muscle cell.

Figure 3

AS-IV suppressed the PDGF-BB-induced switch of HDVSMCs into a proliferative phenotype. Western blot analysis was performed to determine the protein expression levels of muscle cell markers in each group. GAPDH was used as an internal reference.^**P<0.01. Control, HDVSMCs without any treatment; PDGF-BB, HDVSMCs treated with PDGF-BB; PDGF-BB + AS-IV, HDVSMCs treated with PDGF-BB and AS-IV; AS-IV, astragaloside IV; PDGF, platelet-derived growth factor; HDVSMC, human dermal vascular smooth muscle cell; α-SMA, α-smooth muscle actin.

Figure 4

AS-IV attenuated PDGF-BB-induced HDVSMC migration. Transwell assays were performed to determine the rate of HDVSMC migration in each group. ^**P<0.01. Control, HDVSMCs without any treatment; PDGF-BB: HDVSMCs treated with PDGF-BB; PDGF-BB + AS-IV, HDVSMCs treated with PDGF-BB and AS-IV; AS-IV, astragaloside IV; PDGF, platelet-derived growth factor; HDVSMC, human dermal vascular smooth muscle cell.

Figure 5

AS-IV inhibited PDGF-BB-induced upregulation of MMP2 protein expression in HDVSMCs. Western blot analysis was performed to determine the protein expression of MMP2 and MMP9 in each group. GAPDH was used as an internal reference. ^**P<0.01. Control, HDVSMCs without any treatment; PDGF-BB, HDVSMCs treated with PDGF-BB; PDGF-BB + AS-IV, HDVSMCs treated with PDGF-BB and AS-IV; AS-IV, astragaloside IV; PDGF, platelet-derived growth factor; HDVSMC, human dermal vascular smooth muscle cell; MMP, matrix metalloproteinase; ns, not significant.

Figure 6

AS-IV suppressed PDGF-BB-induced activation of the p38 MAPK signaling pathway in HDVSMCs. Western blot analysis was performed to determine the protein expression levels of phosphorylated p38 MAPK, as well as the total p38 MAPK expression level, in each group. GAPDH was used as an internal reference. ^**P<0.01. Control, HDVSMCs without any treatment; PDGF-BB, HDVSMCs treated with PDGF-BB; PDGF-BB + AS-IV, HDVSMCs treated with PDGF-BB and AS-IV; AS-IV, astragaloside IV; PDGF, platelet-derived growth factor; HDVSMC, human dermal vascular smooth muscle cell; MAPK, mitogen activate protein kinase.