[Effect of astaxanthin on vascular smooth muscle cells proliferation induced by platelet derived growth factor-BB]

To investigate the effect of astaxanthin (AST) on vascular smooth muscle cells (VSMCs) proliferation in vitro induced by platelet derived growth factor-BB (PDGF-BB), and to explore its possible mechanism.

There were 4 groups in this experiment: blank control group, PDGF-BB group, PDGF-BB+ AST group, AST group. After the cells received different intervention for the indicated time, the cell growth was determined by Trypan blue staining; cell proliferation was demonstrated using CCK-8 kit; the cell cycle progression was analyzed by flow cytometry, and the mRNA expression of cyclin D1, cyclin E, CDK6, CDK4, cyclin kinase inhibitor protein P21 was determined by real-time PCR; reactive oxygen species (ROS) generation was detected using a Microplate reader; the total and phosphorylated forms of ERK1/2, p38 MAPK, JNK was observed in AST pretreated VSMCs in 5, 10 and 15 min after PDGF-BB treatment by Western blot analysis.

(1) Cell viability: AST and/or PDGF-BB did not induce VSMCs necrosis with the different concentration compared with untreated cells (P>0.05). (2) Cell proliferation: PDGF-BB induced VSMCs proliferation (2.5±0.3 vs 1, P<0.01), while AST reversed the effect in a concentration-dependent manner when co-treated with PDGF-BB (all P<0.01); Cell cycle: Flow cytometry analysis showed that AST at a dose of 25 μmol/L reduced the percentages of cells in S phase and increased the G0/G1 populations in PDGF-BB-stimulated VSMCs; mRNA expression of the check-point proteins: Real Time PCR results demonstrated that, compared with the control group, the mRNA expression of CDK6, CDK4, cyclin D1, cyclin E in the PDGF-BB group was higher (4.20±0.30, 2.90±0.18, 3.50±0.30, 2.70±0.11 vs 1, all P<0.01), while p21 mRNA expression was lower (0.52±0.03 vs 1, P<0.01), while AST reversed these effects when co-treated with PDGF-BB. (3) ROS expression: compared with the control group, ROS level was significantly higher in the PDGF-BB group (2.10±0.09 vs 1, P<0.01), while AST reversed the effect in a concentration-dependent manner when co-treated with PDGF-BB (all P<0.01). (4) Signaling pathway: AST blocking the proliferation of VSMCs induced by PDGF-BB was related to suppress ERK1/2, p-p38 MAPK signaling pathway, but little effect to JNK. Conclutions: These results demonstrate that AST can block the proliferation and migration of VSMCs through G0/G1 to S phase of the cell cycle arrest. Further study indicates that AST suppress PDGF-BB-induced VSMCs proliferation is associated with an inhibition of ROS generation and ERK1/2, p-p38 MAPK signal pathways.