Cilostazol inhibits proliferation and induces apoptosis in rat vascular smooth muscle cells through Rb-p53-p21 pathways / 中华心血管病杂志

<p><b>OBJECTIVE</b>To explore the effects and related mechanisms of cilostazol on rat vascular smooth muscle cells (VSMCs)proliferation.</p><p><b>METHODS</b>VSMCs were treated with DMEM (control) and various doses of cilostazol (1.0×10(-7), 2.5×10(-7), 5.0×10(-7), 7.5×10(-7) and 1.0×10(-6) mol/L) for 13 d (cell counting) or 72 h. Proliferation of VSMCs was investigated by cell-counting, MTT and flow cytometry analysis. Cell apoptosis was determined by TUNEL staining. mRNA and protein expressions of cell cycle regulatory proteins, such as Rb, p53 and p21 were detected by RT-PCR and Western blot, respectively.</p><p><b>RESULTS</b>Cilostazol inhibited VSMCs proliferation and induced VSMCs arrest at G1 phase in a dose-dependent manner. High dose of cilostazol (7.5×10(-7) and 1.0×10(-6) mol/L) induced VSMCs apoptosis. p53 mRNA expression in 2.5×10(-7) mol/L to 7.5×10(-7) mol/L groups as well as 1.0×10(-6) mol/L group (3.22 ± 0.45 vs. 1.75 ± 0.32) and p53 protein expression in 7.5×10(-7) mol/L group and 1.0×10(-6) mol/L group (0.53 ± 0.11 vs. 0.18 ± 0.06) were significantly upregulated after 72 h culture (all P < 0.05 vs. control). Low dose of cilostazol (1.0×10(-7), 2.5×10(-7) and 5.0×10(-7) mol/L) significantly upregulated p21 mRNA expression compared to control group (1.86 ± 0.19, 2.20 ± 0.24 and 2.10 ± 0.18 vs. 1.210 ± 0.18, all P < 0.05). Similarly, Rb mRNA expression was significantly upregulated in 1.0×10(-7), 2.5×10(-7) and 5.0×10(-7) mol/L groups (0.89 ± 0.07 vs. 0.38 ± 0.04)compared with control group (all P < 0.05). However, high dose cilostazol (7.5×10(-7) and 1.0×10(-6) mol/L) significantly downregulated p21 mRNA expression (0.81 ± 0.09 vs. 1.21 ± 0.18, 0.36 ± 0.10 vs. 1.21 ± 0.18, all P < 0.05 vs. control) and Rb mRNA expression (0.12 ± 0.02 and 0.11 ± 0.02 vs. 0.38 ± 0.04, all P < 0.05 vs. control). p21 and Rb protein expressions also upregulated at low concentrations of cilostazol and downregulated at high concentrations of cilostazol.</p><p><b>CONCLUSION</b>Cilostazol could inhibit the proliferation of rat VSMCs through modulating Rb-p53-p21 pathway and induce VSMCs apoptosis through upregulating p53.</p>

Tumor necrosis factor-α promote permeability of human umbilical vein endothelial cells via activating RhoA-ERK1/2 pathway / 中华心血管病杂志

<p><b>OBJECTIVE</b>Tumor necrosis factor-α (TNF-α) is known to induce changes in endothelial cell morphology and permeability. The aim of this study is to determine the underlying signaling mechanisms involved in these responses.</p><p><b>METHODS</b>Cultured human umbilical vein endothelial cells (HUVECs) were exposed to TNF-α, and HUVEC cytoskeletal changes were evaluated by observing fluorescence of F-actin following ligation with labeled antibodies. Endothelial permeability was detected by measuring the flux of horseradish peroxidase (HRP)-albumin across the EC monolayers. To explore the signaling pathways behind TNF-α-induced changes in HUVEC morphology and permeability, HUVECs were treated with either the Rho GTPase inhibitor Y27632 or the mitogen-activated protein kinases (MAPK) inhibitors PD98059 and SB203580 before TNF-α administration. To further elucidate possible involvement of the RhoA and ERK pathways in TNF-α-induced HUVEC changes, retrovirus-carried recombinant dominant-negative forms and constitutive-activative forms of RhoA, namely T19NRhoA and Q63LRhoA, were pre-infected into HUVECs prior to TNF-α exposure.</p><p><b>RESULTS</b>TNF-α induced F-actin cytoskeleton rearrangement and increased HUVEC permeability in a dose and time-dependent manner. The maximal increase in the HRP-BSA flux (40 ng/ml) was seen in cells exposed to TNF-α at 100 ng/ml after 2 h. Preconditioning of HUVEC monolayer with Y27632 or PD98059 significantly reduced TNF-α induced permeability increase (HRP concentration from 40 ng/ml decreased to 12.5 ng/ml, P < 0.05) and F-actin cytoskeleton rearrangement, HUVEC pre-infection with activated forms of Q63LRhoA increased HUVEC permeability and upregulated pERK compared to GFP infection, while HUVEC pre-infection with inhibited forms of T19NRhoA attenuated the effects of TNF-α on HUVEC permeability.</p><p><b>CONCLUSION</b>These results indicate that TNF-α-induced EC barrier dysfunction and morphological changes of the F-actin via activating RhoA-ERK/MAPK signal pathway.</p>