Protective effect of butylated hydroxylanisole against hydrogen peroxide-induced apoptosis in primary cultured mouse hepatocytes

Butylated hydroxyanisole (BHA) is a synthetic phenolic compound consisting of a mixture of two isomeric organic compounds: 2-tert-butyl-4-hydroxyanisole and 3-tert-butyl-4-hydroxyanisole. We examined the effect of BHA against hydrogen peroxide (H2O2)-induced apoptosis in primary cultured mouse hepatocytes. Cell viability was significantly decreased by H2O2 in a dose-dependent manner. Additionally, H2O2 treatment increased Bax, decreased Bcl-2, and promoted PARP-1 cleavage in a dose-dependent manner. Pretreatment with BHA before exposure to H2O2 significantly attenuated the H2O2-induced decrease of cell viability. H2O2 exposure resulted in an increase of intracellular reactive oxygen species (ROS) generation that was significantly inhibited by pretreatment with BHA or N-acetyl-cysteine (NAC, an ROS scavenger). H2O2-induced decrease of cell viability was also attenuated by pretreatment with BHA and NAC. Furthermore, H2O2-induced increase of Bax, decrease of Bcl-2, and PARP-1 cleavage was also inhibited by BHA. Taken together, results of this investigation demonstrated that BHA protects primary cultured mouse hepatocytes against H2O2-induced apoptosis by inhibiting ROS generation.

Epigenetic modulation as a therapeutic approach for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare but progressive and currently incurable disease, which is characterized by vascular remodeling in association with muscularization of the arterioles, medial thickening and plexiform lesion formation. Despite our advanced understanding of the pathogenesis of PAH and the recent therapeutic advances, PAH still remains a fatal disease. In addition, the susceptibility to PAH has not yet been adequately explained. Much evidence points to the involvement of epigenetic changes in the pathogenesis of a number of human diseases including cancer, peripheral hypertension and asthma. The knowledge gained from the epigenetic study of various human diseases can also be applied to PAH. Thus, the pursuit of novel therapeutic targets via understanding the epigenetic alterations involved in the pathogenesis of PAH, such as DNA methylation, histone modification and microRNA, might be an attractive therapeutic avenue for the development of a novel and more effective treatment. This review provides a general overview of the current advances in epigenetics associated with PAH, and discusses the potential for improved treatment through understanding the role of epigenetics in the development of PAH.

Survival of hypoxic human mesenchymal stem cells is enhanced by a positive feedback loop involving miR-210 and hypoxia-inducible factor 1

The use of mesenchymal stem cells (MSCs) has emerged as a potential new treatment for myocardial infarction. However, the poor viability of MSCs after transplantation critically limits the efficacy of this new strategy. The expression of microRNA-210 (miR-210) is induced by hypoxia and is important for cell survival under hypoxic conditions. Hypoxia increases the levels of hypoxia inducible factor-1 (HIF-1) protein and miR-210 in human MSCs (hMSCs). miR-210 positively regulates HIF-1alpha activity. Furthermore, miR-210 expression is also induced by hypoxia through the regulation of HIF-1alpha. To investigate the effect of miR-210 on hMSC survival under hypoxic conditions, survival rates along with signaling related to cell survival were evaluated in hMSCs over-expressing miR-210 or ones that lacked HIF-1alpha expression. Elevated miR-210 expression increased survival rates along with Akt and ERK activity in hMSCs with hypoxia. These data demonstrated that a positive feedback loop involving miR-210 and HIF-1alpha was important for MSC survival under hypoxic conditions.

Potential role of HMG CoA reductase inhibitor on oxidative stress induced by advanced glycation endproducts in vascular smooth muscle cells of diabetic vasculopathy

Advanced glycation endproducts (AGEs)-induced vascular smooth muscle cell (VSMCs) proliferation and formation of reactive oxygen species (ROS) are emerging as one of the important mechanisms of diabetic vasculopathy but little is known about the antioxidative action of HMG CoA reductase inhibitor (statin) on AGEs. We hypothesized that statin might reduce AGEs-induced intracellular ROS of VSMCs and analyzed the possible mechanism of action of statin in AGEs-induced cellular signaling. Aortic smooth muscle cell of Sprague-Dawley rat (RASMC) culture was done using the different levels of AGEs stimulation in the presence or absence of statin. The proliferation of RASMC, ROS formation and cellular signaling was evaluated and neointimal formation after balloon injury in diabetic rats was analyzed. Increasing concentration of AGEs stimulation was associated with increased RASMC proliferation and increased ROS formation and they were decreased with statin in a dose-dependent manner. Increased NF-kappaB p65, phosphorylated ERK, phosphorylated p38 MAPK, cyclooxygenase-2, and c-jun by AGEs stimulation were noted and their expression was inhibited by statin. Neointimal formation after balloon injury was much thicker in diabetic rats than the sham-treated group but less neointimal growth was observed in those treated with statin after balloon injury. Increased ROS formation, subsequent activation of MAPK system and increased VSMC proliferation may be possible mechanisms of diabetic vasculopathy induced by AGEs and statin may play a key role in the treatment of AGEs-induced diabetic atherosclerosis.

The Inhibition of Insulin-stimulated Proliferation of Vascular Smooth Muscle Cells by Rosiglitazone Is Mediated by the Akt-mTOR-P70S6K Pathway

PURPOSE: Thiazolidinediones (TZDs) are known to inhibit the proliferation of vascular smooth muscle cell (VSMC) by increasing the activity of p27(Kip1) and retinoblastoma protein (RB). However, the upstream signaling mechanisms associated with this pathway have not been elucidated. The Akt-mTOR-P70S6 kinase pathway is the central regulator of cell growth and proliferation, and increases cell proliferation by inhibiting the activities of p27(Kip1) and retinoblastoma protein (RB). Therefore, we hypothesized in this study that rosiglitazone inhibits VSMC proliferation through the inhibition of the Akt-TOR-P70S6K signaling pathway. MATERIALS and METHODS: Rat aortic smooth muscle cells (RAoSMCs) were treated with 10microM of rosiglitazone 24 hours before the addition of insulin as a mitogenic stimulus. Western blot analysis was performed to determine the inhibitory effect of rosiglitazone treatment on the Akt-mTOR-P70S6K signaling pathway. Carotid balloon injury was also performed in Otsuka Long-Evans Tokushima Fatty (OLETF) diabetic rats that were pretreated with 3 mg/kg of rosiglitazone. RESULTS: Western blot analysis demonstrated significant inhibition of activation of p-Akt, p-m-TOR, and p-p70S6K in cells treated with rosiglitazone. The inhibition of the activation of the p-mTOR-p-p70S6K pathway seemed to be mediated by both the upstream PI3K pathway and MEK-ERK complex. CONCLUSION: The inhibitory effect of rosiglitazone on RAoSMC proliferation in vitro and in vivo is mediated by the inhibition of the Akt-mTOR-P70S6K pathway.

Pathobiological role of advanced glycation endproducts via mitogen-activated protein kinase dependent pathway in the diabetic vasculopathy

Advanced glycation endproducts (AGEs) have been reported to play a role in neointimal formation and increase the rate of in-stent restenosis (ISR) in the diabetic coronary artery disease patients treated with stents, but the potential pathogenic mechanisms of AGEs in vascular smooth muscle cell proliferation remain unclear. We sought to determine the AGEs related pathobiological mechanism of diabetic vasculopathy. Rat aortic smooth muscle cell (RAoSMC) culture was done with different concentrations of AGEs and proliferation was assessed. Immunohistochemistry for receptor of AGEs (RAGE) was performed with human carotid atheroma. Western blotting was performed to assess the activation of MAP kinase system in the cultured RAoSMC. AGEs increased RAoSMC proliferation and were associated with increased phosphorylation of ERK and p38 kinase by time and dose dependent manner. The MAP kinase activity was decreased by RNA interference for RAGE. AGEs stimulation increased reactive oxygen species (ROS) generation in cultured RAoSMC. From this study it is concluded that AGEs played a key role in RAoSMC proliferation via MAP kinase dependent pathways. Activation of vascular smooth muscle cell (VSMC) proliferation by MAP kinase system and increased formation of ROS may be the possible mechanisms of AGEs induced diabetic vasculopathy.