Sesquiterpene Lactone Suppresses Vascular Smooth Muscle Cell Proliferation and Migration via Inhibition of Cell Cycle Progression

Significant difference between sirolimus and paclitaxel nanoparticles in anti-proliferation effect in normoxia and hypoxia: The basis of better selection of atherosclerosis treatment

Compared with paclitaxel, sirolimus has been more used in the treatment of vascular restenosis gradually as an anti-proliferative drug, but few basic studies have elucidated its mechanism. The anti-proliferative effects of sirolimus or paclitaxel have been demonstrated by numerous studies under normoxia, but few studies have been achieved focusing hypoxia. In this study, porcine carotid artery injury model and classical cobalt chloride hypoxia cell model were established. Sirolimus nanoparticles (SRM-NPs), paclitaxel nanoparticles (PTX-NPs) and blank nanoparticles (Blank-NPs) were prepared respectively. The effect of RPM-NPs on the degree of stenosis, proliferative index and the expression of PCNA after 28 days of porcine carotid artery injury model was evaluated. Compared with saline group and SRM groups, SRM-NPs group suppressed vascular stenosis, proliferative index and the expression of PCNA (P < 0.01 and P < 0.05). Endothelial cell (EC) and smooth muscle cell (SMC) were pre-treated with cobaltous chloride, followed by SRM-NPs, PTX-NPs, Blank-NPs or PBS control treating, the effects on cell proliferation, HIF-1 expression and glycolysis were detected. SRM-NPs could inhibit EC and SMC proliferation under hypoxia, while PTX-NPs couldn't (P < 0.001). Significant differences between sirolimus and paclitaxel NPs in anti-proliferation effect under normoxia and hypoxia may due to the different inhibitory effects on HIF-1α expression and glycolysis. In conclusion, these results suggest that sirolimus can inhibit the proliferation of hypoxic cells more effectively than paclitaxel. These observations may provide a basis for understanding clinical vascular stenosis therapeutic differences between rapamycin and paclitaxel.

Dehydrocostus lactone inhibits in vitro gastrinoma cancer cell growth through apoptosis induction, sub-G1 cell cycle arrest, DNA damage and loss of mitochondrial membrane potential

INTRODUCTION

The purpose of the present study was to evaluate the antiproliferative activity of dehydrocostus lactone against human BON-1 cancer cell lines and to explore the possible underlying mechanism.

MATERIAL AND METHODS

MTT cell viability assay was used to determine cytotoxic effects of dehydrocostus lactone in BON-1 cells. Fluorescence and transmission electron microscopic (TEM) techniques were used to study the effect of the compound on cellular morphology and apoptosis. Flow cytometry was used to assess the effect on cell cycle phase distribution. Effects of the drug on cell apoptosis and mitochondrial membrane potential were analyzed by flow cytometry using annexin v and rhodamine-123 as fluorescent probes.

RESULTS

The results of the present study indicated that dehydrocostus lactone significantly (p < 0.01) inhibited the growth of BON-1 cancer cells. These growth inhibitory effects of dehydrocostus lactone on BON-1 were found to be time and concentration-dependent. The IC50 of dehydrocostus lactone were found to be 71.9 μM and 52.3 μM at 24 and 48 h time intervals respectively. The growth inhibitory effects of dehydrocostus lactone were found to be due to loss of mitochondrial membrane potential, the induction of apoptosis and sub-G1 cell cycle arrest.

CONCLUSIONS

Dehydrocostus inhibits in vitro gastrinoma cancer cell growth and therefore may prove beneficial in the management of gastrinoma cancer.

Up-regulation of Pim-3 in Chronic Obstructive Pulmonary Disease (COPD) patients and its potential therapeutic role in COPD rat modeling

BACKGROUND

Pim-3 belongs to the PIM kinase family and plays an important role in promoting inflammation, which is essential in the pathogenesis of Chronic Obstructive Pulmonary Disease (COPD).

METHODS

Immunohistochemistry (IHC), western blot, and RT-PCR analyses were performed to assess the expression of Pim-3 in both COPD and healthy lung tissue samples. SMA (Smooth Muscle Actin) and Cyclin D1 expression were detected by IHC. We also constructed animal models for the control, COPD, and Pim-3 inhibition groups, in order to analyze the effects of Pim-3 inhibition on COPD, and the role of Pim-3 in the p38 pathway.

RESULTS

Compared with normal lung tissue, Pim-3 mRNA and protein were up-regulated in COPD tissue. Expression of Cyclin D1 and SMA were also up-regulated in the COPD group. In the animal model experiment, we found that suppression of Pim-3 decreased Pim-3, Cyclin D1, and SMA expression, as well as ameliorated lung damage in COPD patients. The inhibition of Pim-3 also resulted in the suppression of the p38 pathway.

CONCLUSION

Our study suggests that up-regulation of Pim-3 successfully accelerated COPD development, and aggravated lung damage. The molecular mechanism of Pim-3 in COPD might be related to the p38 pathway, and is correlated with Cyclin D1 and SMA expression.

A potential therapeutic effect of CYP2C8 overexpression on anti-TNF-α activity

Epoxyeicosatrienoic acids (EETs) are generated from arachidonic acid catalysed by cytochrome P450 (CYP) epoxygenases. In addition to regulating vascular tone EETs may alleviate inflammation and ROS. The present study was conducted to determine whether CYP2C8 gene overexpression was able to increase the level of EETs, and subsequently prevent TNF-α induced inflammation and reactive oxygen species (ROS) in human umbilical vein endothelial cells (HUVECs) and macrophages. Peroxisome proliferator-activated receptor γ (PPARγ) activation, nuclear factor-κB (NF-κB) activation, endothelial nitric oxide synthase (eNOS) activation, gp-91 activation, and inflammatory cytokine expression were detected by western blot analysis or enzyme-linked immunosorbent assay. Intracellular reactive oxygen species (ROS) was measured by flow cytometry, while the migration of vascular smooth muscle cells (VSMCs) was detected by Transwell assay. pCMV-mediated CYP2C8 overexpression and its metabolites, EETs, markedly suppressed TNF-α induced inflammatory cytokines IL-6 and MCP-1 expression via the activation of NF-κB and degradation of IκBα. Moreover, pretreatment with 11,12-EET significantly blocked TNF-α-induced ROS production. CYP2C8-derived EETs also effectively alleviated the migration of VSMCs and improved the function of endothelial cells through the upregulation of eNOS, which was significantly decreased under the stimulation of TNF-α. Furthermore, these protective effects observed were mediated by PPARγ activation. To the best of our knowledge, the results of the present study demonstrated for the first time that CYP2C8-derived EETs exerted antivascular inflammatory and anti-oxidative effects, at least in part, through the activation of PPARγ. Thus, the CYP2C8 gene may be useful in the prevention and treatment of vascular inflammatory diseases.

Fluorofenidone attenuates hepatic fibrosis by suppressing the proliferation and activation of hepatic stellate cells

Fluorofenidone (AKF-PD) is a novel pyridone agent. The purpose of this study is to investigate the inhibitory effects of AKF-PD on liver fibrosis in rats and the involved molecular mechanism related to hepatic stellate cells (HSCs). Rats treated with dimethylnitrosamine or CCl4 were randomly divided into normal, model, AKF-PD treatment, and pirfenidone (PFD) treatment groups. The isolated primary rat HSCs were treated with AKF-PD and PFD respectively. Cell proliferation and cell cycle distribution were analyzed by bromodeoxyuridine and flow cytometry, respectively. The expression of collagen I and α-smooth muscle actin (α-SMA) were determined by Western blot, immunohistochemical staining, and real-time RT-PCR. The expression of cyclin D1, cyclin E, and p27(kip1) and phosphorylation of MEK, ERK, Akt, and 70-kDa ribosomal S6 kinase (p70S6K) were detected by Western blot. AKF-PD significantly inhibited PDGF-BB-induced HSC proliferation and activation by attenuating the expression of collagen I and α-SMA, causing G0/G1 phase cell cycle arrest, reducing expression of cyclin D1 and cyclin E, and promoting expression of p27(kip1). AKF-PD also downregulated PDGF-BB-induced MEK, ERK, Akt, and p70S6K phosphorylation in HSCs. In rat liver fibrosis, AKF-PD alleviated hepatic fibrosis by decreasing necroinflammatory score and semiquantitative score, and reducing expression of collagen I and α-SMA. AKF-PD attenuated the progression of hepatic fibrosis by suppressing HSCs proliferation and activation via the ERK/MAPK and PI3K/Akt signaling pathways. AKF-PD may be used as a potential novel therapeutic agent against liver fibrosis.

Diethylstilbestrol induces arrest of rat vascular smooth muscle cell cycle progression through downregulation of cyclin D1 and cyclin E

Cardiovascular disease is associated with a multitude of pathophysiologic conditions, including vascular smooth muscle cell (VSMC) proliferation in response to vessel injury. Diethylstilbestrol (DES) was previously prescribed for at-risk pregnancies to prevent abortion, miscarriage, and premature labor. Our aim in this study was to elucidate the effects and molecular mechanism of DES on proliferation and cell cycle progression of platelet-derived growth factor (PDGF)-BB-stimulated rat aortic VSMCs. Treating the cells with DES (1-7 μM) dramatically inhibited cell proliferation in a dose-dependent manner without any cytotoxic effects. In addition, DES blocked cell cycle progression from PDGF-BB-stimulated cells, which we found was related to down-regulation of the cell cycle regulatory factors, cyclin D1, and cyclin E. Our data demonstrate that DES inhibits rat aortic VSMC proliferation and cell cycle progression through regulation of cell cycle-related proteins. Therefore, our observations may explain, in part, the mechanistic basis underlying the therapeutic effects of DES in cardiovascular disease.

Pharmacology in health food: metabolism of quercetin in vivo and its protective effect against arteriosclerosis

Quercetin, a member of the bioflavonoids family, has been proposed to have anti-atherogenic, anti-inflammatory, and anti-hypertensive properties leading to the beneficial effects against cardiovascular diseases. It was recently demonstrated that quercetin 3-O-β-D-glucuronide (Q3GA) is one of the major quercetin conjugates in human plasma, in which the aglycone could not be detected. Although most of the in vitro pharmacological studies have been carried out using only the quercetin aglycone form, experiments using Q3GA would be important to discover the preventive mechanisms of cardiovascular diseases by quercetin in vivo. Therefore we examined the effects of the chemically synthesized Q3GA, as an in vivo form, on vascular smooth muscle cell (VSMC) disorders related to the progression of arteriosclerosis. Platelet-derived growth factor-induced cell migration and proliferation were inhibited by Q3GA in VSMCs. Q3GA attenuated angiotensin II-induced VSMC hypertrophy via its inhibitory effect on JNK and the AP-1 signaling pathway. Q3GA scavenged 1,1-diphenyl-2-picrylhydrazyl radical measured by the electron paramagnetic resonance method. In addition, immunohistochemical studies with monoclonal antibody 14A2 targeting the Q3GA demonstrated that the positive staining specifically accumulates in human atherosclerotic lesions, but not in the normal aorta. These findings suggest Q3GA would be an active metabolite of quercetin in plasma and may have preventative effects on arteriosclerosis relevant to VSMC disorders.

Impaired peroxisome proliferator-activated receptor-gamma contributes to phenotypic modulation of vascular smooth muscle cells during hypertension

The phenotypic modulation of vascular smooth muscle cells (VSMCs) plays a pivotal role in hypertension-induced vascular changes including vascular remodeling. The precise mechanisms underlying VSMC phenotypic modulation remain elusive. Here we test the role of peroxisome proliferator-activated receptor (PPAR)-gamma in the VSMC phenotypic modulation during hypertension. Both spontaneously hypertensive rat (SHR) aortas and SHR-derived VSMCs exhibited reduced PPAR-gamma expression and excessive VSMC phenotypic modulation identified by reduced contractile proteins, alpha-smooth muscle actin (alpha-SMA) and smooth muscle 22alpha (SM22alpha), and enhanced proliferation and migration. PPAR-gamma overexpression rescued the expression of alpha-SMA and SM22alpha, and inhibited the proliferation and migration in SHR-derived VSMCs. In contrast, PPAR-gamma silencing exerted the opposite effect. Activating PPAR-gamma using rosiglitazone in vivo up-regulated aortic alpha-SMA and SM22alpha expression and attenuated aortic remodeling in SHRs. Increased activation of phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling was observed in SHR-derived VSMCs. PI3K inhibitor LY294002 rescued the impaired expression of contractile proteins, and inhibited proliferation and migration in VSMCs from SHRs, whereas constitutively active PI3K mutant had the opposite effect. Overexpression or silencing of PPAR-gamma inhibited or excited PI3K/Akt activity, respectively. LY294002 counteracted the PPAR-gamma silencing induced proliferation and migration in SHR-derived VSMCs, whereas active PI3K mutant had the opposite effect. In contrast, reduced proliferation and migration by PPAR-gamma overexpression were reversed by the active PI3K mutant, and further inhibited by LY294002. We conclude that PPAR-gamma inhibits VSMC phenotypic modulation through inhibiting PI3K/Akt signaling. Impaired PPAR-gamma expression is responsible for VSMC phenotypic modulation during hypertension. These findings highlight an attractive therapeutic target for hypertension-related vascular disorders.

Development of an optimized protocol for primary culture of smooth muscle cells from rat thoracic aortas

Primary culture of smooth muscle cells has been widely used as a valuable tool to study the molecular mechanisms underlying atherosclerosis and restenosis. Currently, tissue explants and enzymatic digestion methods are frequently applied to produce smooth muscle cells. Explants method is time consuming, usually taking several weeks. The enzymatic digestion method requires large amounts of proteolytic enzymes to generate enough cells for cardiovascular research. The present study reports an optimized method by combining both techniques to obtain high purity smooth muscle cells. The cultured cells exhibited the characteristic "hills and valleys" growth pattern as observed by phase contrast microscopy and showed alpha-SM-actin positive staining by indirect immunocytochemistry and immunofluorescence. Purity of the cells is guaranteed by the lack of von Willebrand Factor immunoreactivity. Finally, the cultured cells well proliferate on oxidized-LDL stimulation, suggesting the practical utility of this new method.