Plasma exosomes confer hypoxic pulmonary hypertension by transferring LOX-1 cargo to trigger phenotypic switching of pulmonary artery smooth muscle cells.

The pulmonary vascular remodeling (PVR), the pathological basis of pulmonary hypertension (PH), entails pulmonary artery smooth muscle cells (PASMCs) phenotypic switching, but appreciation of the underlying mechanisms is incomplete. Exosomes, a novel transfer machinery enabling delivery of its cargos to recipient cells, have been recently implicated in cardiovascular diseases including PH. The two critical questions of whether plasma-derived exosomes drive PASMCs phenotypic switching and what cargo the exosomes transport, however, remain unclear. Herein, by means of transmission electron microscopy and protein detection, we for the first time, characterized lectin like oxidized low-density lipoprotein receptor-1 (LOX-1) as a novel cargo of plasma-derived exosomes in PH. With LOX-1 knockout (Olr1-/-) rats-derived exosomes, we demonstrated that exosomal LOX-1 could be transferred into PASMCs and thus elicited cell phenotypic switching. Of importance, Olr1-/- rats exhibited no cell phenotypic switching and developed less severe PH, but administration of wild type rather than Olr1-/- exosomes to Olr1-/- rats recapitulated the phenotype of PH with robust PASMCs phenotypic switching. We also revealed that exosomal LOX-1 triggered PASMCs phenotypic switching, PVR and ultimately PH via ERK1/2-KLF4 signaling axis. This study has generated proof that plasma-derived exosomes confer PH by delivering LOX-1 into PASMCs. Hence, exosomal LOX-1 represents a novel exploitable target for PH prevention and treatment.

MicroRNA-137 Inhibited Hypoxia-Induced Proliferation of Pulmonary Artery Smooth Muscle Cells by Targeting Calpain-2.

The proliferation of pulmonary artery smooth muscle cells (PASMCs) is an important cause of pulmonary vascular remodeling in pulmonary hypertension (PH). It has been reported that miR-137 inhibits the proliferation of tumor cells. However, whether miR-137 is involved in PH remains unclear. In this study, male Sprague-Dawley rats were subjected to 10% O2 for 3 weeks to establish PH, and rat primary PASMCs were treated with hypoxia (3% O2) for 48 h to induce cell proliferation. The effect of miR-137 on PASMC proliferation and calpain-2 expression was assessed by transfecting miR-137 mimic and inhibitor. The effect of calpain-2 on PASMC proliferation was assessed by transfecting calpain-2 siRNA. The present study found for the first time that miR-137 was downregulated in pulmonary arteries of hypoxic PH rats and in hypoxia-treated PASMCs. miR-137 mimic inhibited hypoxia-induced PASMC proliferation and upregulation of calpain-2 expression in PASMCs. Furthermore, miR-137 inhibitor induced the proliferation of PASMCs under normoxia, and knockdown of calpain-2 mRNA by siRNA significantly inhibited hypoxia-induced proliferation of PASMCs. Our study demonstrated that hypoxia-induced downregulation of miR-137 expression promoted the proliferation of PASMCs by targeting calpain-2, thereby potentially resulting in pulmonary vascular remodeling in hypoxic PH.

Aspirin ameliorates pulmonary vascular remodeling in pulmonary hypertension by dampening endothelial-to-mesenchymal transition.

Pulmonary vascular remodeling (PVR) is the pathological basis of pulmonary hypertension (PH). Incomplete understanding of PVR etiology has hindered drug development for this devastating disease, which exhibits poor prognosis despite the currently available therapies. Endothelial-to-mesenchymal transition (EndMT), a process of cell transdifferentiation, has been recently implicated in cardiovascular diseases, including PH. But the questions of how EndMT occurs and how to pharmacologically target EndMT in vivo have yet to be further answered. Herein, by performing hematoxylin-eosin and immunofluorescence staining, transmission electron microscopy and Western blotting, we found that EndMT plays a key role in the pathogenesis of PH, and importantly that aspirin, a FDA-approved widely used drug, was capable of ameliorating PVR in a preclinical rat model of hypoxia-induced PH. Moreover, aspirin exerted its inhibitory effects on EndMT in vitro and in vivo by suppressing HIF-1α/TGF-ß1/Smads/Snail signaling pathway. Our data suggest that EndMT represents an intriguing drug target for the prevention and treatment of hypoxic PH and that aspirin may be repurposed to meet the urgent therapeutic needs of hypoxic PH patients.

MEIS1 regulated proliferation and migration of pulmonary artery smooth muscle cells in hypoxia-induced pulmonary hypertension.

AIM: Proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) are regarded as the primary factors resulting in pulmonary arterial remodeling in pulmonary hypertension (PH). Myeloid ecotropic viral integration site 1 (MEIS1) has been positioned as a negative cardiomyocyte cell cycle regulator and regulates proliferation of multiple kinds of cancer cells. Whether MESI1 is involved in the proliferation and migration of PASMCs deserves to be identified. MAIN METHODS: Sprague Dawley rats were exposed to hypoxia condition (10% O2) for 4 weeks to induce PH and primary rat PASMCs were cultured in hypoxia condition (3% O2) for 48 h to induce proliferation and migration. Immunohistochemistry, immunofluorescence, reverse transcription PCR and Western blot analysis were performed to detect the expressions of target mRNAs and proteins. EDU, CCK8 and wound healing assays were conducted to measure the proliferation and migration of PASMCs. KEY FINDINGS: Hypoxia down-regulated the expression of MEIS1 (both mRNA and protein) in pulmonary arteries and PASMCs. Over-expression of MEIS1 inhibited the proliferation and migration of PASMCs afforded by hypoxia. In contrast, knockdown of MEIS1 under normoxia condition like hypoxia induced the proliferation and migration of PASMCs. MEIS1 mediated hypoxia-induced the proliferation and migration of PASMCs via METTL14/MEIS1/p21 signaling. SIGNIFICANCE: The present study revealed that MEIS1 regulated the proliferation and migration of PASMCs during hypoxia-induced PH. Thus, MEIS1 may be a potential target for PH therapy.

Up-regulation of cullin7 promotes proliferation and migration of pulmonary artery smooth muscle cells in hypoxia-induced pulmonary hypertension.

It has well been demonstrated that E3 ubiquitin ligase cullin7 plays important roles in cancer cell growth control via down-regulating p53 expression. The noncanonical function or the pathogenic role of p53 has more recently been implicated in pulmonary vascular remodeling. Therefore, whether cullin7 participates in hypoxia-induced pulmonary vascular remodeling deserves to be elucidated. The present study found that hypoxia up-regulated the expression of cullin7 mRNA and protein in pulmonary arteries and pulmonary artery smooth muscle cells, and knockdown of cullin7 inhibited hypoxia-induced proliferation and migration of pulmonary artery smooth muscle cells and reversed hypoxia-induced inhibition of p53 expression. Notably, administration of proteasome inhibitor MG132 significantly inhibited the expression of cullin7 and up-regulated the expression of p53 in pulmonary arteries concomitantly with improvement of hypoxia-induced pulmonary vascular remodeling. Our study demonstrated that hypoxia induced up-regulation of cullin7 expression resulting to the proliferation and migration of pulmonary artery smooth muscle cells via down-regulating p53 expression, which contributed to pulmonary vascular remodeling.

Down-regulation of miR-204 attenuates endothelial-mesenchymal transition by enhancing autophagy in hypoxia-induced pulmonary hypertension.

Pulmonary arterial remodeling is a crucial cause of increased pulmonary artery pressure during pulmonary hypertension (PH). Recently, growing evidence has upheld the contribution of endothelial-mesenchymal transition (EndMT) to pulmonary arterial remodeling, but the underlying mechanisms remain largely unaddressed. miR-204 has been implicated in PH, being anti-proliferative and pro-apoptotic in pulmonary artery smooth muscles cells (PASMCs), but its role in EndMT is still unknown. Here we found that miR-204 was down-regulated by hypoxia in rat pulmonary arterial intima and human pulmonary artery endothelial cells (HPAECs), and its further down-regulation by using miR-204 inhibitor suppressed hypoxia-induced EndMT. Moreover, autophagy, evoked by hypoxia in rat pulmonary arterial intima and HPAECs, suppressed hypoxia-induced EndMT via p62-dependent degradation of Snail and Twist. Additionally, autophagy was regulated by miR-204 targeting ATG7. While down-regulation of miR-204 in PASMCs reportedly promoted monocrotaline-induced pulmonary arterial hypertension via increased cell proliferation, our data suggested an important, albeit dichotomous, role of miR-204 down-regulation in endothelial cells in the process of EndMT that it attenuated EndMT by enhancing autophagy, thereby ameliorating hypoxia-induced PH to some extent.

miR-27a promotes endothelial-mesenchymal transition in hypoxia-induced pulmonary arterial hypertension by suppressing BMP signaling.

AIM: Growing evidence suggests that endothelial-mesenchymal transition (EndMT) play key roles in pulmonary arterial remodeling during pulmonary arterial hypertension (PAH), but the underlying mechanisms have yet to be fully understood. miR-27a has been shown to promote proliferation of pulmonary arterial cells during PAH, but its role in EndMT remains unexplored. This study was designed to investigate the role and underlying mechanism of miR-27a in EndMT during PAH. MAIN METHODS: Rats were exposed in hypoxia (10% O2) for 3 weeks to induce PAH, and human pulmonary artery endothelial cells (HPAECs) were exposed in hypoxia (1% O2) for 48 h to induce EndMT. Immunohistochemistry, in situ hybridization, immunofluorescence, real-time PCR and Western blot were conducted to detect the expressions of RNAs and proteins, and luciferase assay was used to verify the putative binding site of miR-27a. KEY FINDINGS: We found that hypoxia up-regulated miR-27a in the tunica intima of rat pulmonary arteries and HPAECs, and that inhibition of miR-27a suppressed hypoxia-induced EndMT. Furthermore, elevated expression of miR-27a suppressed bone morphogenetic protein (BMP) signaling by targeting Smad5, thereby lessening Id2-mediated repression of the 2 critical mediators of EndMT (Snail and Twist). SIGNIFICANCE: Our data unveiled a novel role of miR-27a in EndMT during hypoxia-induced PAH. Thus, targeting of miR-27a-related pathway may be therapeutically harnessed to treat PAH.

Epigallocatechin-3-gallate ameliorates hypoxia-induced pulmonary vascular remodeling by promoting mitofusin-2-mediated mitochondrial fusion.

Pulmonary hypertension (PH) mainly results from excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and displays mitochondrial abnormalities such as mitochondrial fragmentation. Epigallocatechin-3-gallate (EGCG), an efficient antiproliferative compound in green tea, has recently been demonstrated to inhibit PASMCs proliferation. However, the pre-clinical issues as to whether EGCG attenuates PH and the underlying mechanisms have yet to be addressed. The present study was undertaken to investigate the therapeutic effects of EGCG on PH and its effects on mitochondrial fragmentation in PASMCs. Rats exposed to hypoxia (10% O2, 3 weeks) developed PH. EGCG (50, 100 or 200mg/kg/d, i.g.) dose-dependently attenuated right ventricular systolic pressure, pulmonary vascular remodeling and right ventricular hypertrophy, increased expression of mitochondrial fusion protein - mitofusin-2 (MFN-2), and promoted mitochondrial fusion as evidenced by decreased number and volume of mitochondria in PASMCs of pulmonary arteries. Notably, EGCG (50µM) downregulated hypoxia-induced (3% O2, 48h) PASMCs mitochondrial fragmentation and inhibited PASMCs proliferation via KLF-4/MFN-2/p-Erk signaling pathway. Collectively, our data demonstrated that EGCG exerts antiproliferative effects via regulating mitochondrial fragmentation of PASMCs and EGCG holds the promise as a drug against PH.

Negative feedback regulation between microRNA let-7g and LOX-1 mediated hypoxia-induced PASMCs proliferation.

BACKGROUND: Pulmonary hypertension (PH) is a proliferative disorder associated with enhanced proliferation and suppressed apoptosis of pulmonary artery smooth muscle cells (PASMCs). Our lately study demonstrated that let-7g inhibited hypoxia-induced proliferation of PASMCs via repressing c-myc-Bmi-1-p16 signaling pathway. However, the upstream of let-7g has not yet been fully defined. Previous studies have shown that LOX-1, a target of let-7g, could also regulate the expression of let-7g in human aortic endothelial cells. In this present study, we aimed to investigate whether there is a negative feedback regulation between microRNA let-7g and LOX-1 in hypoxia-induced proliferation of PASMCs. METHODS: SD Rats were exposed to hypoxia (10% O2, 3 weeks) to induce PH. HE staining was used to evaluate pulmonary artery remodeling. in situ hybridization and immunohistochemistry were performed to assess the expression and distribution of let-7g and LOX-1, respectively. MTS, EDU and flow cytometry were performed to evaluate PASMCs proliferation. Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting were conducted to assess the expression of let-7g, LOX-1, calpain-1,-2,-4, and OCT-1. RESULTS: The expression of let-7g was significantly down-regulated in pulmonary arteries of hypoxia-induced PH rats accompanied by pulmonary vascular remodeling, whereas let-7g mimic inhibited hypoxia-induced proliferation of PASMCs and up-regulation of LOX-1 expression. LOX-1 blocking reversed hypoxia-induced down-regulation of let-7g expression. Calpains, protein kinase C and OCT-1 were involved in negative feedback regulation between let-7g and LOX-1. CONCLUSION: Negative feedback regulation between let-7g and LOX-1 mediated hypoxia-induced proliferation of in PASMCs.

AG4, a compound isolated from Radix Ardisiae Gigantifoliae, induces apoptosis in human nasopharyngeal cancer CNE cells through intrinsic and extrinsic apoptosis pathways.

3ß-O-{α-L-Pyran rhamnose-(1→3)-[ß-D-xylopyranose-(1→2)]-ß-D-glucopyranose-(1→4)-[ß-D-lucopyranose-(1→2)]-α-L-pyran arabinose}-cyclamiretin A (AG4) is a saponin component obtained from the Giantleaf Ardisia Rhizome (Rhizoma Ardisiae Gigantifoliae). The present study aimed to investigate the antitumor potential of AG4 and its possible mechanisms in human nasopharyngeal carcinoma cells (CNE). We exposed tumor cells to AG4 to investigate which cell line was the most sensitive to AG4. Cell viability was assessed using the MTT reduction assay, and the effects of AG4 on apoptosis, reactive oxygen species (ROS) content, mitochondrial membrane potential (MMP), and cell cycle were detected using a flow cytometer; the glutathione, superoxide dismutase and malondialdehyde activities were measured using colorimetric methods. The relative expressions of Bax, Bad, Bid, Bcl-2, and Fas mRNA were calculated using the (Equation is included in full-text article.)comparative method by real-time PCR studies and protein was detected by western blotting. AG4 markedly inhibited the growth of CNE cells by decreasing cell proliferation, inducing apoptosis, and blocking the cell cycle in the S phase. The release of caspase-3, caspase-8, and caspase-9 was stimulated by AG4 in CNE, and the decreased proliferation induced by AG4 was blocked by the inhibitor of pan caspase (Z-VAD-FMK). Moreover, the MMP was decreased in AG4-treated cells, and AG4-induced cell apoptosis was accompanied by a rapid and lasting increase in ROS, which was abolished by N-acetyl-L-cysteine (NAC); glutathione, superoxide dismutase, and malondialdehyde were regulated by AG4. AG4 inhibited Bcl-2 mRNA and protein expression and stimulated Bax, Bad, Bid, Fas mRNA, and protein expression in CNE cultures, suggesting an effect at the transcriptional and protein level. In addition, both the FasL inhibitor (AF-016) and the Bcl-2 family inhibitor (GX15-070) could prevent the cell apoptosis induced by AG4. The findings suggested that AG4-induced apoptosis in CNE cells involved a death receptor pathway and a Bcl-2 family-mediated mitochondrial signaling pathway by decreasing the MMPs in an ROS-dependent manner and regulating genes and proteins relative to apoptosis; also, regulation of cell cycles may also play a role in the antitumor mechanism of AG4.

Effects of (20S*,24R*)-epoxy-9,19-cyclolanstane-3ß,12ß,16ß,25-pentaol-3-O-ß-D-xylopyranoside extracted from rhizoma Beesia on immunoregulation and anti-inflammation.

(20S*,24R*)-epoxy-9,19-cyclolanstane-3ß,12ß,16ß,25-pentaol-3-O-ß-D-xylopyranoside (BC1) is a kind of natural bioactive substance extracted from Beesia calthaefolia (Maxim.)Ulbr. This study was designed to evaluate the effects of BC1 on the proliferation of lymphocytes, phagocytosis of peritoneal macrophage, and cytokine secretion, such as tumor necrosis factor (TNF)-α and interleukin (IL)-1ß, and the foot pad thickness index, which is beneficial for understanding the mechanism of BC1 on immunoregulation and anti-inflammation and also will benefit our further research. The proliferation of splenic lymphocyte induced by mitogen (concanavalin A or lipopolysaccharide (LPS)) was detected using the cell counting kit assay. The neutral red phagocytic test of macrophages was determined by colorimetric method. The gene and protein expressions of TNF-α and IL-1ß were measured by real time RT-PCR and ELISA in serum, spleen, and lymphocytes, respectively. In vitro, our present study has shown that BC1 (31.25-250 µg/ml) could inhibit the proliferation of splenic lymphocyte and phagocytosis of macrophages, and inhibit the increased production of TNF-α and IL-1ß in protein and gene levels. In mice, LPS could increase the gene and protein expressions of TNF-α and IL-1ß, respectively, but BC1 (12.5-50 µg/kg) could recover the increased gene and protein expressions of TNF-α and IL-1ß induced by LPS in the spleen and serum of mice. Treatment of arthritic rats with BC1 (1.5 mg/kg body weight) resulted in a significant reduction in foot pad thickness index and serum TNF-α level comparable to the indomethacin-treated arthritic rats, proving its anti-inflammatory effect. Thus, the function of immunoregulation of BC1 may be accomplished through modulating the gene and protein expressions of TNF-α and IL-1ß.

New cycloartane triterpene glycosides from Beesia calthaefolia.

Two new cycloartane triterpene glycosides (compounds 1 and 4) were isolated from the whole plants of Beesia calthaefolia with two known glycosides (compounds 2 and 3). Compounds 1 and 4 were assigned as (20S(*),24R(*))-16ß-acetoxy-20, 24-epoxy-9, 19-cyclolanostane-3ß,12ß,15α,18,25-pentaol-3-O-ß-d-xylopyranoside and (20S(*),24 R(*))-16ß-acetoxy-20,24-epoxy-9,19-cyclolanostane-3ß,15α,18,25-tetraol-3-O-ß-d-xylopyranoside, respectively. Their structures were elucidated on the basis of extensive spectroscopic data analyses and comparison with spectroscopic data reported. Compounds 1 and 4 showed potential inhibition activity for the proliferation of splenocytes.

Sanguinarine inhibits vascular endothelial growth factor release by generation of reactive oxygen species in MCF-7 human mammary adenocarcinoma cells.

The inhibitory action and the possible mechanism of anticancer compound Sanguinarine (SAN) on vascular endothelial growth factor (VEGF) in human mammary adenocarcinoma cells MCF-7 were evaluated in this study. We exposed MCF-7 to SAN for 24 h, then cell viability was assessed by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay. Human VEGF was measured using a paired antibody quantitative ELISA kit, relative expression of VEGF mRNA was calculated using the real-time PCR studies, and the effect of SAN on the reactive oxygen species (ROS) level was detected by the flow cytometer. Treatment with SAN remarkably inhibited growth of MCF-7 cells and induced cell apoptosis. We found that VEGF release was stimulated by subtoxic concentrations of SAN and inhibited by high dose of SAN, SAN-evoked VEGF release was mimicked by low concentration of H2O2, and SAN-regulated VEGF inhibition was accompanied by increasing of ROS; these changes were abolished by antioxidant. High concentration of SAN inhibited VEGF mRNA expression in MCF-7 cultures, suggesting an effect at transcriptional level, and was also abolished by antioxidant. The present findings indicated that the regulation of VEGF expression and release from MCF-7 cells were possibly through reactive oxygen species evoked by SAN.