Heat shock protein 90 inhibitor AUY922 attenuates platelet-derived growth factor-BB-induced migration and proliferation of vascular smooth muscle cells

Biophysically stressed vascular smooth muscle cells express MCP-1 via a PDGFR-β-HMGB1 signaling pathway

Vascular smooth muscle cells (VSMCs) under biophysical stress play an active role in the progression of vascular inflammation, but the precise mechanisms are unclear. This study examined the cellular expression of monocyte chemoattractant protein 1 (MCP-1) and its related mechanisms using cultured rat aortic VSMCs stimulated with mechanical stretch (MS, equibiaxial cyclic stretch, 60 cycles/ min). When the cells were stimulated with 10% MS, MCP-1 expression was markedly increased compared to those in the cells stimulated with low MS intensity (3% or 5%). An enzyme-linked immunosorbent assay revealed an increase in HMGB1 released into culture media from the cells stimulated with 10% MS compared to those stimulated with 3% MS. A pretreatment with glycyrrhizin, a HMGB1 inhibitor, resulted in the marked attenuation of MCP-1 expression in the cells stimulated with 10% MS, suggesting a key role of HMGB1 on MCP-1 expression. Western blot analysis revealed higher PDGFR-α and PDGFR-β expression in the cells stimulated with 10% MS than 3% MS-stimulated cells. In the cells deficient of PDGFR-β using siRNA, but not PDGFR-α, HMGB1 released into culture media was significantly attenuated in the 10% MS-stimulated cells. Similarly, MCP-1 expression induced in 10% MS-stimulated cells was also attenuated in cells deficient of PDGFR-β. Overall, the PDGFR-β signaling plays a pivotal role in the increased expression of MCP-1 in VSMCs stressed with 10% MS. Therefore, targeting PDGFR-β signaling in VSMCs might be a promising therapeutic strategy for vascular complications in the vasculatures under excessive biophysical stress.

Far-Infrared Irradiation Decreases Proliferation in Basal and PDGF-Stimulated VSMCs Through AMPK-Mediated Inhibition of mTOR/p70S6K Signaling Axis

BACKGROUND

Far-infrared (FIR) irradiation has been reported to improve diverse cardiovascular diseases, including heart failure, hypertension, and atherosclerosis. The dysregulated proliferation of vascular smooth muscle cells (VSMCs) is well established to contribute to developing occlusive vascular diseases such as atherosclerosis and in-stent restenosis. However, the effects of FIR irradiation on VSMC proliferation and the underlying mechanism are unclear. This study investigated the molecular mechanism through which FIR irradiation inhibited VSMC proliferation.

METHODS

We performed cell proliferation and cell death assay, adenosine 5'-triphosphate (ATP) assay, inhibitor studies, transfection of dominant negative (dn)-AMP-activated protein kinase (AMPK) α1 gene, and western blot analyses. We also conducted confocal microscopic image analyses and ex vivo studies using isolated rat aortas.

RESULTS

FIR irradiation for 30 minutes decreased VSMC proliferation without altering the cell death. Furthermore, FIR irradiation accompanied decreases in phosphorylation of the mammalian target of rapamycin (mTOR) at Ser2448 (p-mTOR-Ser2448) and p70 S6 kinase (p70S6K) at Thr389 (p-p70S6K-Thr389). The phosphorylation of AMPK at Thr172 (p-AMPK-Thr172) was increased in FIR-irradiated VSMCs, which was accompanied by a decreased cellular ATP level. Similar to in vitro results, FIR irradiation increased p-AMPK-Thr172 and decreased p-mTOR-Ser2448 and p-p70S6K-Thr389 in isolated rat aortas. Pre-treatment with compound C, a specific AMPK inhibitor, or ectopic expression of dn-AMPKα1 gene, significantly reversed FIR irradiation-decreased VSMC proliferation, p-mTOR-Ser2448, and p-p70S6K-Thr389. On the other hand, hyperthermal stimulus (39°C) did not alter VSMC proliferation, cellular ATP level, and AMPK/mTOR/p70S6K phosphorylation. Finally, FIR irradiation attenuated platelet-derived growth factor (PDGF)-stimulated VSMC proliferation by increasing p-AMPK-Thr172, and decreasing p-mTOR-Ser2448 and p-p70S6K-Thr389 in PDGF-induced in vitro atherosclerosis model.

CONCLUSION

These results show that FIR irradiation decreases the basal and PDGF-stimulated VSMC proliferation, at least in part, by the AMPK-mediated inhibition of mTOR/p70S6K signaling axis irrespective of its hyperthermal effect. These observations suggest that FIR therapy can be used to treat arterial narrowing diseases, including atherosclerosis and in-stent restenosis.

Radotinib attenuates TGFβ -mediated pulmonary fibrosis in vitro and in vivo: exploring the potential of drug repurposing

BACKGROUND

Tyrosine kinase (TK) plays a crucial role in the pathogenesis of idiopathic pulmonary fibrosis. Here, we aimed to investigate whether radotinib (Rb) could inhibit pulmonary fibrosis by inhibiting TK in vitro and in vivo.

METHODS

The antifibrotic effects of Rb in transforming growth factor-β (TGF-β)1-stimulated A549 cells were determined using real-time polymerase chain reaction, western blotting, and immunocytochemistry assays. Rb inhibition of bleomycin-induced lung fibrosis in Sprague Dawley (SD) rats was determined by histopathological and​ immunohistochemical analyses. Rb-interfering metabolites were analyzed using LC-MS/MS.

RESULTS

Rb concentrations of up to 1000 nM did not affect the viability of A549 cells, but Rb (30 nM) significantly reduced expression of TGF-β1 (10 ng/mL)-induced ECM factors, such as Snail, Twist, and F-actin. Rb also regulated TGF-β1-overexpressed signal cascades, such as fibronectin and α-smooth muscle actin. Furthermore, Rb attenuated the phosphorylation of Smad2 and phosphorylation of kinases, such as, extracellular signal-regulated kinase, and protein kinase B. In the inhibitory test against bleomycin (5 mg/kg)-induced lung fibrosis, the Rb (30 mg/kg/daily)-treated group showed a half-pulmonary fibrosis region compared to the positive control group. In addition, Rb significantly reduced collagen type I and fibronectin expression in the bleomycin-induced fibrotic region of SD rats. Further, the identified metabolite pantothenic acid was not altered by Rb.

CONCLUSION

Taken together, these results indicate that Rb inhibits TGF-β1-induced pulmonary fibrosis both in vitro and in vivo. These findings suggest that Rb may be an effective treatment for pulmonary fibrosis-related disorders and idiopathic pulmonary fibrosis.

Inhibition of Connexin 43 reverses ox-LDL-mediated inhibition of autophagy in VSMC by inhibiting the PI3K/Akt/mTOR signaling pathway

Background

Oxidized low-density lipoproteins (ox-LDL) may induce foam cell formation from the vascular smooth muscle cell (VSMC) by inhibiting VSMC autophagy. This process accelerates the formation of atherosclerosis (AS). Connexin 43 (Cx43), which is the most widely distributed connexin in VSMC is associated with autophagy. However, the mechanism of action and the involvement of Cx43 in ox-LDL-inhibited VSMC autophagy remain unclear.

Methods

The primary VSMC were obtained and identified, before primary VSMC were pretreated with an inhibitor (Cx43-specific inhibitor Gap26 and PI3K inhibitor LY294002) and stimulated with ox-LDL.

Results

Ox-LDL not only inhibited autophagy in VSMC via downregulation of autophagy-related proteins (such as Beclin 1, LC3B, p62), but also increased Cx43 protein levels. Then we added Gap26 to VSMC in the ox-LDL+Gap26 group, in which autophagy-related proteins were increased and the accumulation of lipid droplets was reduced. These result suggested that an enhanced level of autophagy and an alleviation of lipid accumulation might be caused by inhibiting Cx43 in VSMC. The phosphorylation levels of PI3K, AKT, mTOR were increased by ox-LDL, thus down-regulating autophagy-related proteins. However, this situation was partially reversed by the Gap26. Moreover, Cx43 expression were decreased by LY294002 in ox-LDL-induced VSMCs.

Conclusion

Inhibiting Cx43 may activate VSMC autophagy to inhibit foam cell formation by inhibiting the PI3K/AKT/mTOR signaling pathway.

Sulfiredoxin-1 Inhibits PDGF-BB-Induced Vascular Smooth Muscle Cell Proliferation and Migration by Enhancing the Activation of Nrf2/ARE Signaling

Sulfiredoxin1 (Srxn1), an endogenous antioxidant protein, is involved in cardiovascular diseases. In this study, we aimed to investigate the role of Srxn1 in VSMCs and its molecular mechanism. The murine vascular smooth muscle cells MOVAS were treated with different doses of platelet-derived growth factor-BB (PDGF-BB); then, Srxn1 expression was detected using reverse transcription-quantitative polymerase chain reaction and western blot analysis. MTT and wound healing assay were used to examine the effect of Srxn1 on MOVAS cell proliferation and migration. Reactive oxygen species (ROS) production, malondialdehyde (MDA) level, and superoxide dismutase (SOD) activity in MOVAS cells were detected using corresponding commercial kits. Moreover, the expression of proliferating cell nuclear antigen (PCNA), matrix metalloproteinase 2 (MMP-2), and nuclear factor erythroid-2-related factor 2 (Nrf2) /antioxidant response element (ARE) signaling-related proteins was detected using western blot analysis. In our study, PDGF-BB dose-dependently increased Srxn1 expression in MOVAS cells, and Srxn1 expression was increased with time dependence in PDGF-BB-treated MOVAS cells. The knockdown of Srxn1 increased PDGF-BB-induced the proliferation, migration, ROS production, MDA level, and the protein expression of PCNA and MMP-2, as well as decreased SOD activity and the expression of Nrf2/ARE signaling-related proteins in PDGF-BB-stimulated MOVAS cells. However, the overexpression of Srxn1 showed the opposite results to those of knockdown of Srxn1. Moreover, the inhibitory effects of Srxn1 overexpression on PDGF-BB induced proliferation, migration, ROS production, and MDA level and the promotion of Srxn1 overexpression on PDGF-BB induced SOD activity were partially reversed by the knockdown of Nrf2. Srxn1 inhibited PDGF-BB-induced proliferation, migration, and oxidative stress through activating Nrf2/ARE signaling.