Hong Jiang

Sinomenine, a pure alkaloid extract from Sinomenium acutum, has anti-inflammatory and immunoregulatory functions. This study investigated the efficiency and the signalling pathways involved in the effect of sinomenine on vascular smooth muscle cell (VSMC) dedifferentiation in response to platelet-derived growth factor (PDGF)-BB stimulation and vascular injury. VSMCs were isolated from rat aorta and preincubated with sinomenine before being stimulated with PDGF-BB. WST and BrdU incorporation assays were used to evaluate VSMC proliferation. Flow cytometric analysis was performed for testing the cell cycle progression. The cell migration of VSMCs were analysed using a Transwell system. The expression of VSMC specific genes and signalling proteins were tested by Western blot. For the animal study, C57/BL6 mice were fed either normal rodent chow diets or sinomenine chow diets that supplemented with 0.09 % sinomenine (w/w) in the normal chows for 14 days before carotid artery wire injury. PDGF-BB activated the dedifferentiation of VSMCs characterised by decreased expression of SMA, Smoothelin and SM22α. However, sinomenine treatment preserved the dedifferentiation in response to PDGF-BB. The activations of mitogen-activated protein kinase extracellular signal-regulated kinases, Akt, GSK3β and STAT3 induced by PDGF-BB were also inhibited in sinomenine-treated VSMCs. In vivo evidence with wire-injured mice exhibited a reduction in neointimal area and an increase in smooth muscle-specific gene expression in the sinomenine-treated group. In this study, we found that sinomenine-suppressed VSMC phenotype switching induced by PDGF-BB in vitro and neointimal formation in vivo. Therefore, sinomenine is a potential candidate to be used in the treatment of vascular proliferative disease.

Vascular smooth muscle cell (VSMC) proliferation plays a critical role in the development of vascular diseases. In the present study, we tested the efficacy and the mechanisms of action of gastrodin, a bioactive component of the Chinese herb Gastrodia elata Bl, in relation to platelet-derived growth factor-BB (PDGF-BB)-dependent cell proliferation and neointima formation after acute vascular injury. Cell experiments were performed with VSMCs isolated from rat aortas. WST and BrdU incorporation assays were used to evaluate VSMC proliferation. Eight-week-old C57BL/6 mice were used for the animal experiments. Gastrodin (150 mg/kg/day) was administered in the animal chow for 14 days, and the mice were subjected to wire injury of the left carotid artery. Our data demonstrated that gastrodin attenuated the VSMC proliferation induced by PDGF-BB, as assessed by WST assay and BrdU incorporation. Gastrodin influenced the S-phase entry of VSMCs and stabilised p27Kip1 expression. In addition, pre-incubation with sinomenine prior to PDGF-BB stimulation led to increased smooth muscle-specific gene expression, thereby inhibiting VSMC dedifferentiation. Gastrodin treatment also reduced the intimal area and the number of PCNA-positive cells. Furthermore, PDGF-BB-induced phosphorylation of ERK1/2, p38 MAPK, Akt and GSK3β was suppressed by gastrodin. Our results suggest that gastrodin can inhibit VSMC proliferation and attenuate neointimal hyperplasia in response to vascular injury. Furthermore, the ERK1/2, p38 MAPK and Akt/GSK3β signalling pathways were found to be involved in the effects of gastrodin.

J. Neurochem. (2012) 122, 834–843. Src homology 2 domain–containing protein tyrosine phosphatase substrate–1 (SHPS‐1), also known as Signal‐regulatory protein alpha (SIRPα) or SIRPA is a transmembrane protein that is predominantly expressed in neurons, dendritic cells, and macrophages. This study was conducted to investigate the role of SHPS‐1 in the oxidative stress and brain damage induced by acute focal cerebral ischemia. Wild‐type (WT) and SHPS‐1 mutant (MT) mice were subjected to middle cerebral artery occlusion (60 min) followed by reperfusion. SHPS‐1 MT mice had significantly reduced infarct volumes and improved neurological function after brain ischemia. In addition, neural injury and oxidative stress were inhibited in SHPS‐1 MT mice. The mRNA and protein levels of the antioxidant genes nuclear factor‐E2‐related factor 2 (Nrf2) and heme oxygenase 1 were up‐regulated in SHPS‐1 MT mice. The SHPS‐1 mutation suppressed the phosphorylation of SHP‐1 and SHP‐2 and increased the phosphorylation of Akt and GSK3β. These results provide the first demonstration that SHPS‐1 plays an important role in the oxidative stress and brain injury induced by acute cerebral ischemia. The activation of Akt signaling and the up‐regulation of Nrf2 and heme oxygenase 1 likely account for the protective effects that were observed in the SHPS‐1 MT mice.

3, 3′diindolylmethane (DIM), a natural phytochemical, has shown inhibitory effects on the growth and migration of a variety of cancer cells; however, whether DIM has similar effects on vascular smooth muscle cells (VSMCs) remains unknown. The purpose of this study was to assess the effects of DIM on the proliferation and migration of cultured VSMCs and neointima formation in a carotid injury model, as well as the related cell signaling mechanisms. DIM dose-dependently inhibited the platelet-derived growth factor (PDGF)-BB-induced proliferation of VSMCs without cell cytotoxicity. This inhibition was caused by a G0/G1 phase cell cycle arrest demonstrated by fluorescence-activated cell-sorting analysis. We also showed that DIM-induced growth inhibition was associated with the inhibition of the expression of cyclin D1 and cyclin-dependent kinase (CDK) 4/6 as well as an increase in p27^Kip1 levels in PDGF-stimulated VSMCs. Moreover, DIM was also found to modulate migration of VSMCs and smooth muscle-specific contractile marker expression. Mechanistically, DIM negatively modulated PDGF-BB-induced phosphorylation of PDGF-recptorβ (PDGF-Rβ) and the activities of downstream signaling molecules including Akt/glycogen synthase kinase(GSK)3β, extracellular signal-regulated kinase1/2 (ERK1/2), and signal transducers and activators of transcription 3 (STAT3). Our in vivo studies using a mouse carotid arterial injury model revealed that treatment with 150 mg/kg DIM resulted in significant reduction of the neointima/media ratio and proliferating cell nuclear antigen (PCNA)-positive cells, without affecting apoptosis of vascular cells and reendothelialization. Infiltration of inflammatory cells was also inhibited by DIM administration. These results demonstrate that DIM can suppress the phenotypic modulation of VSMCs and neointima hyperplasia after vascular injury. These beneficial effects on VSMCs were at least partly mediated by the inhibition of PDGF-Rβ and the activities of downstream signaling pathways. The results suggest that DIM has the potential to be a candidate for the prevention of restenosis.

Abnormal proliferation, migration, and phenotypic modulation of vascular smooth muscle cells (VSMCs) are critical factors in neointima formation during restenosis. The purpose of this study is to determine the efficacy and possible cell signaling mechanisms of apigenin in VSMC activation induced by platelet‐derived growth factor (PDGF)‐BB and injury‐induced neointima formation. Our data revealed a dose‐dependent apigenin inhibition of PDGF‐BB‐induced proliferation of VSMCs by arresting cells in G0/G1‐phase of the cell cycle as determined using 5‐bromo‐2′‐deoxyuridine incorporation and flow cytometry. This was associated with the inhibition of cyclin‐dependent kinase (CDK) 4,6 expression and an increase in p27Kip1 levels in PDGF‐stimulated VSMCs. Moreover, apigenin was also found to regulate PDGF‐induced migration and expression of smooth‐muscle‐specific contractile markers. Mechanistically, the PDGF‐BB‐induced phosphorylation of PDGF‐receptor β (PDGF‐Rβ), Akt/glycogen synthase kinase(GSK)3β, extracellular signal‐regulated kinase1/2 (ERK1/2), and signal transducers and activators of transcription 3 (STAT3) is negatively modulated by apigenin. For the in vivo studies using a mouse carotid arterial injury model, the administration of apigenin resulted in a significant inhibition of the neointima/media ratio and proliferating cell nuclear antigen (PCNA)‐positive cells. These results demonstrate that apigenin can suppress PDGF‐induced VSMC activation and neointima hyperplasia after vascular injury; these beneficial effects are probably the result of the blockade of PDGF‐Rβ phosphorylation and its downstream signal transduction, including the Akt/GSK‐3β, ERK1/2, and STAT3 pathways. The results suggest that apigenin may be a potential therapeutic candidate for the prevention of restenosis. J. Cell. Biochem. 113: 1198–1207, 2012.