ABSTRACT
Objective To explore the effects of ginsenoside metabolite Compound K (CK) on TNF-α-induced RANTES secretion in human bronchial epithelial cell line BEAS-2B and to elucidate its possible mechanism. Methods BEAS-2B cells were cultured and treated with CK in different dosages, and then the secretion of RANTES in BEAS-2B cells exposed to inflammatory stimuli was measured by ELISA kits. Expressions of RANTES mRNA and protein were detected by RT-PCR and Western blotting analysis, respectively. Reporter gene assay was employed to elucidate the interaction between CK and activator protein 1(AP-1), glucocorticoid receptor (GR). CK antagonist mifepristone was used to observe whether the inhibitory effect of CK against RANTES was mediated by GR. Results TNF-α-induced secretion of RANTES in BEAS-2B was markedly inhibited by CK (3-30 μmol/L). Treatment with CK also reduced RANTES mRNA and protein expression. Reporter gene assays indicated that CK was a GR agonist and could repress TNF-α-induced AP-1 transactivation. The inhibitory effects of CK on RANTES secretion were antagonized by mifepristone, suggesting a pivotal role of GR. Conclusion These results suggest that CK may inhibit TNF-α-induced RANTES secretion in human bronchial epithelial cells, which might be associated with GR pathway activation and AP-1 pathway inhibition.
ABSTRACT
Abnormal proliferation of vascular smooth muscle cells (VSMCs) plays an important role in several pathological processes of cardiovascular diseases. In this study, the effects of XCT790, a potent and selective inverse agonist of estrogen-related receptor alpha (ERRalpha), on rat VSMCs proliferation and related signal pathways were investigated. The proliferative activity of VSMCs was determined by CCK-8 assay. The mRNA levels of ERRalpha, PGC-1alpha, OPN and MCAD were assayed by RT-PCR. The protein levels of ERRalpha, ERK2 and p-ERK1/2 were evaluated by Western blotting. ELISA was used to assess the protein expression of VEGF. The results showed that XCT790 (5-20 micromol x L(-1)) inhibited rat VSMCs proliferation, and the expression of ERRalpha and its target genes, as well as p-ERK1/2, were also inhibited. XCT790 inhibited VSMCs proliferation in a dose-dependent manner at the dose range from 5 to 20 micromol x L(-1) and in a time-dependent manner at the dose range from 10 to 20 micromol x L(-1). These findings demonstrate that XCT790 inhibits rat VSMCs proliferation by down-regulating the gene level of ERRalpha and thus inhibiting the ERK signal pathway, suggesting that ERRalpha may be a novel potential target for therapeutic approaches to inhibit VSMCs proliferation, which plays an important role in several cardiovascular diseases.