AIm:TO investigate the effect of farrerol,a major active component isolated from a traditional Chinese herb"Man-shan-hong"(the dried Ieaves of Rhododendron dauncum L)on fetal bovine serum(FBS)-induced proliferation of cultured vascular smooth muscle cells (VSMCs)of rat thoracic aorta.Methods:VSMCs proliferation,DNA synthesis and cell cycle progression were studied using the MTT assay,bromodeoxyuridine(BrdU)incorporation and flow cytometry,respectively.The mRNA levels of cell cycle proteins were quantified using real-time RT-PCR, and the phosphorylation of ERKl/2 was determined using Western blotting.Reporter gene and receptor binding assays were employed to study the interaction between farrerol and estrogen receptors(ERs).Results:FarreroI(0.3-10 μmol/L)inhibited VSMC proliferation and DNA synthesis induced by 5%FBS in a concentration-dependent manner.The effects were associated with G,cell cycle arrest.down-regulation of cell cycle proteins and reduction in FBS-induced ERKl/2 phosphorylation.Using a reporter gene.it was found that farrerol(3 μmol/L)induced 2.1-fold transcription of ER.In receptor binding assays, farrerol inhibited the binding of [3H]estradiol for ERa and ERβ with IC50 values of 57 μmol/L and 2.7 μmol/L, respectively.implying that farrerol had a higher affinity for ERl3.Finally,the inhibition of VSMC proliferation by farrerol(3 μmol/L)was abolished by the specific ERβ antagonist PHTPP(5 μmol/L).Conclusion:FarreroI acts as a functional phytoestrogen to inhibit FBS-induced VSMC proliferation, mainly via interaction with ERβ,which may be helpful in the treatment of cardiovascular diseases related to abnormal VSMCs proliferation.
展开▼
