Toll-like Receptor 2 Mediates VEGF Overexpression and Mesothelial Hyperpermeability in Tuberculous Pleural Effusion.

Toll-like receptor (TLR) is essential for the immune response to Mycobacterium tuberculosis (MTB) infection. However, the mechanism whereby TLR mediates the MTB-induced pleural mesothelial hyperpermeability in tuberculous pleural effusion (TBPE) remains unclear. Pleural effusion size and pleural fluid levels of vascular endothelial growth factor (VEGF) and soluble TLR2 (sTLR2) in patients with TBPE (n = 36) or transudative pleural effusion (TPE, n = 16) were measured. The effects of MTB H37Ra (MTBRa) on pleural mesothelial permeability and the expression of VEGF and zonula occludens (ZO)-1 in human pleural mesothelial cells (PMCs) were assessed. Levels of VEGF and sTLR2 were significantly elevated in TBPE compared to TPE. Moreover, effusion VEGF levels correlated positively, while sTLR2 values correlated negatively, with pleural effusion size in TBPE. In human PMCs, MTBRa substantially activated JNK/AP-1 signaling and upregulated VEGF expression, whereas knockdown of TLR2 remarkably inhibited MTBRa-induced JNK phosphorylation and VEGF overexpression. Additionally, both MTBRa and VEGF markedly reduced ZO-1 expression and induced pleural mesothelial permeability, while TLR2 silencing or pretreatment with anti-VEGF antibody significantly attenuated the MTBRa-triggered effects. Collectively, TLR2 mediates VEGF overproduction and downregulates ZO-1 expression in human PMCs, leading to mesothelial hyperpermeability in TBPE. Targeting TLR2/VEGF pathway may confer a potential treatment strategy for TBPE.

Yohimbine, an α2-Adrenoceptor Antagonist, Suppresses PDGF-BB-Stimulated Vascular Smooth Muscle Cell Proliferation by Downregulating the PLCγ1 Signaling Pathway.

Yohimbine (YOH) has antiproliferative effects against breast cancer and pancreatic cancer; however, its effects on vascular proliferative diseases such as atherosclerosis remain unknown. Accordingly, we investigated the inhibitory mechanisms of YOH in vascular smooth muscle cells (VSMCs) stimulated by platelet-derived growth factor (PDGF)-BB, a major mitogenic factor in vascular diseases. YOH (5-20 µM) suppressed PDGF-BB-stimulated a mouse VSMC line (MOVAS-1 cell) proliferation without inducing cytotoxicity. YOH also exhibited antimigratory effects and downregulated matrix metalloproteinase-2 and -9 expression in PDGF-BB-stimulated MOVAS-1 cells. It also promoted cell cycle arrest in the initial gap/first gap phase by upregulating p27Kip1 and p53 expression and reducing cyclin-dependent kinase 2 and proliferating cell nuclear antigen expression. We noted phospholipase C-γ1 (PLCγ1) but not ERK1/2, AKT, or p38 kinase phosphorylation attenuation in YOH-modulated PDGF-BB-propagated signaling pathways in the MOVAS-1 cells. Furthermore, YOH still inhibited PDGF-BB-induced cell proliferation and PLCγ1 phosphorylation in MOVAS-1 cells with α2B-adrenergic receptor knockdown. YOH (5 and 10 mg/kg) substantially suppressed neointimal hyperplasia in mice subjected to CCA ligation for 21 days. Overall, our results reveal that YOH attenuates PDGF-BB-stimulated VSMC proliferation and migration by downregulating a α2B-adrenergic receptor-independent PLCγ1 pathway and reduces neointimal formation in vivo. Therefore, YOH has potential for repurposing for treating atherosclerosis and other vascular proliferative diseases.

Quercetin blocks the aggressive phenotype of triple-negative breast cancer by inhibiting IGF1/IGF1R-mediated EMT program.

The cancer-preventive activities of quercetin have been extensively studied in invasive breast cancer; however, the role of quercetin on triple-negative breast cancer (TNBC) with overexpression of insulin-like growth factor-1 receptor (IGF1R) has not been resolved. In this article, we demonstrated that quercetin inhibited the activation of IGF1R and its downstream kinases Akt and Erk1/2 in a dose-dependent manner in human MDA-MB-231 breast cancer cells (TNBC cell line). Related to this, quercetin markedly suppressed the metastatic phenotype and epithelial-mesenchymal transition (EMT) of MDA-MB-231 cells by inhibiting the expression of EMT transcription factors Snail and Slug. Quercetin also increased the secretion of IGF-binding protein-3 in the conditioned medium of MDA-MB-231 cells while reducing the secretion of IGF1; thus, quercetin interrupted the autocrine or paracrine loop of IGF1 signaling. In xenograft mouse models, the administration of quercetin blocked the growth of MDA-MB-231 tumor xenografts and their lung metastasis, accompanied by the inactivation of IGF1R and the downregulation of the expression of Snail, Slug, and mesenchymal markers fibronectin and vimentin. These results suggest that quercetin has cancer-preventive value for TNBC by inhibiting IGF1/IGF1R signaling and preventing the consequent EMT and metastasis of TNBC.

Thrombin Upregulates PAI-1 and Mesothelial-Mesenchymal Transition Through PAR-1 and Contributes to Tuberculous Pleural Fibrosis.

Thrombin is an essential procoagulant and profibrotic mediator. However, its implication in tuberculous pleural effusion (TBPE) remains unknown. The effusion thrombin and plasminogen activator inhibitor-1 (PAI-1) levels were measured among transudative pleural effusion (TPE, n = 22) and TBPE (n = 24) patients. Pleural fibrosis, identified as radiological residual pleural thickening (RPT) and shadowing, was measured at 12-month follow-up. Moreover, in vivo and in vitro effects of thrombin on PAI-1 expression and mesothelial-mesenchymal transition (MMT) were assessed. We demonstrated the effusion thrombin levels were significantly higher in TBPE than TPE, especially greater in TBPE patients with RPT > 10mm than those without, and correlated positively with PAI-1 and pleural fibrosis area. In carbon black/bleomycin-treated mice, knockdown of protease-activated receptor-1 (PAR-1) markedly downregulated α-smooth muscle actin (α-SMA) and fibronectin, and attenuated pleural fibrosis. In pleural mesothelial cells (PMCs), thrombin concentration-dependently increased PAI-1, α-SMA, and collagen I expression. Specifically, Mycobacterium tuberculosis H37Ra (MTBRa) induced thrombin production by PMCs via upregulating tissue factor and prothrombin, and PAR-1 silencing considerably abrogated MTBRa-stimulated PAI-1 expression and MMT. Consistently, prothrombin/PAR-1 expression was evident in the pleural mesothelium of TBPE patients. Conclusively, thrombin upregulates PAI-1 and MMT and may contribute to tuberculous pleural fibrosis. Thrombin/PAR-1 inhibition may confer potential therapy for pleural fibrosis.

Endothelin-1 Induces Mesothelial Mesenchymal Transition and Correlates with Pleural Fibrosis in Tuberculous Pleural Effusions.

Endothelin (ET)-1 is involved in various fibrotic diseases. However, its implication in pleural fibrosis remains unknown. We aimed to study the profibrotic role of ET-1 in tuberculous pleural effusion (TBPE). The pleural effusion ET-1 levels were measured among 68 patients including transudative pleural effusion (TPE, n = 12), parapneumonic pleural effusion (PPE, n = 20), and TBPE (n = 36) groups. Pleural fibrosis, defined as radiological residual pleural thickening (RPT) and shadowing, was measured at 12-month follow-up. Additionally, the effect of ET-1 on mesothelial mesenchymal transition (MMT) and extracellular matrix (ECM) producion in human pleural mesothelial cells (PMCs) was assessed. Our findings revealed that effusion ET-1 levels were significantly higher in TBPE than in TPE and PPE, and were markedly higher in TBPE patients with RPT >10 mm than those with RPT ≤10 mm. ET-1 levels correlated substantially with residual pleural shadowing and independently predicted RPT >10 mm in TBPE. In PMCs, ET-1 time-dependently induced MMT with upregulation of α-smooth muscle actin and downregulation of E-cadherin, and stimulated ECM production; furthermore, ET receptor antagonists effectively abrogated these effects. In conclusion, ET-1 induces MMT and ECM synthesis in human PMCs and correlates with pleural fibrosis in TBPE. This study confers a novel insight into the pathogenesis and potential therapies for fibrotic pleural diseases.

Mechanisms of TQ-6, a Novel Ruthenium-Derivative Compound, against Lipopolysaccharide-Induced In Vitro Macrophage Activation and Liver Injury in Experimental Mice: The Crucial Role of p38 MAPK and NF-κB Signaling.

Several studies have reported that metal complexes exhibit anti-inflammatory activities; however, the molecular mechanism is not well understood. In this study, we used a potent ruthenium (II)-derived compound, [Ru(η6-cymene)2-(1H-benzoimidazol-2-yl)-quinoline Cl]BF4 (TQ-6), to investigate the molecular mechanisms underlying the anti-inflammatory effects against lipopolysaccharide (LPS)-induced macrophage activation and liver injury in mice. Treating LPS-stimulated RAW 264.7 cells with TQ-6 suppressed nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in a concentration-dependent manner. The LPS-induced expression of tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1ß) were reduced in TQ-6-treated cells. TQ-6 suppressed, LPS-stimulated p38 MAPK phosphorylation, IκBα degradation, and p65 nuclear translocation in cells. Consistent with the in vitro studies, TQ-6 also suppressed the expression of iNOS, TNF-α, and p65 in the mouse model with acute liver injury induced by LPS. The present study showed that TQ-6 could protect against LPS-induced in vitro inflammation in macrophage and in vivo liver injury in mice, and suggested that NF-κB could be a promising target for protecting against LPS-induced inflammation and liver injury by TQ-6. Therefore, TQ-6 can be a potential therapeutic agent for treating inflammatory diseases.

1-(2-Hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione Induces G1 Cell Cycle Arrest and Autophagy in HeLa Cervical Cancer Cells.

The natural agent, 1-(2-hydroxy-5-methylphenyl)-3-phenyl-1,3-propanedione (HMDB), has been reported to have growth inhibitory effects on several human cancer cells. However, the role of HMDB in cervical cancer remains unclear. Herein, we found that HMDB dose- and time-dependently inhibited growth of HeLa cervical cancer cells, accompanied with G1 cell cycle arrest. HMDB decreased protein expression of cyclins D1/D3/E and cyclin-dependent kinases (CDKs) 2/4/6 and reciprocally increased mRNA and protein levels of CDK inhibitors (p15, p16, p21, and p27), thereby leading to the accumulation of hypophosphorylated retinoblastoma (Rb) protein. HMDB also triggered the accumulation of acidic vesicles and formation of microtubule-associated protein-light chain 3 (LC3), followed by increased expression of LC3 and Beclin-1 and decreased expression of p62, suggesting that HMDB triggered autophagy in HeLa cells. Meanwhile, suppression of the expression of survivin and Bcl-2 implied that HMDB-induced autophagy is tightly linked to apoptosis. Exploring the action mechanism, HMDB induced autophagy via the modulation of AMP-activated protein kinase (AMPK) and mTOR signaling pathway rather than the class III phosphatidylinositol 3-kinase pathway. These results suggest that HMDB inhibits HeLa cell growth by eliciting a G1 arrest through modulation of G1 cell cycle regulators and by concomitantly inducing autophagy through the mediation of AMPK-mTOR and Akt-mTOR pathways, and may be a promising antitumor agent against cervical cancer.

3,5,4'-Trimethoxystilbene, a natural methoxylated analog of resveratrol, inhibits breast cancer cell invasiveness by downregulation of PI3K/Akt and Wnt/ß-catenin signaling cascades and reversal of epithelial-mesenchymal transition.

The molecular basis of epithelial-mesenchymal transition (EMT) functions as a potential therapeutic target for breast cancer because EMT may endow breast tumor-initiating cells with stem-like characteristics and enable the dissemination of breast cancer cells. We have recently verified the antitumor activity of 3,5,4'-trimethoxystilbene (MR-3), a naturally methoxylated derivative of resveratrol, in colorectal cancer xenografts via an induction of apoptosis. The effect of MR-3 on EMT and the invasiveness of human MCF-7 breast adenocarcinoma cell line were also explored. We found that MR-3 significantly increased epithelial marker E-cadherin expression and triggered a cobblestone-like morphology of MCF-7 cells, while reciprocally decreasing the expression of mesenchymal markers, such as snail, slug, and vimentin. In parallel with EMT reversal, MR-3 downregulated the invasion and migration of MCF-7 cells. Exploring the action mechanism of MR-3 on the suppression of EMT and invasion indicates that MR-3 markedly reduced the expression and nuclear translocation of ß-catenin, accompanied with the downregulation of ß-catenin target genes and the increment of membrane-bound ß-catenin. These results suggest the involvement of Wnt/ß-catenin signaling in the MR-3-induced EMT reversion of MCF-7 cells. Notably, MR-3 restored glycogen synthase kinase-3ß activity by inhibiting the phosphorylation of Akt, the event required for ß-catenin destruction via a proteasome-mediated system. Overall, these findings indicate that the anti-invasive activity of MR-3 on MCF-7 cells may result from the suppression of EMT via down-regulating phosphatidylinositol 3-kinase (PI3K)/AKT signaling, and consequently, ß-catenin nuclear translocation. These occurrences ultimately lead to the blockage of EMT and the invasion of breast cancer cells.

Se-methylselenocysteine inhibits lipopolysaccharide-induced NF-κB activation and iNOS induction in RAW 264.7 murine macrophages.

SCOPE: Se-methyl-L-selenocysteine (MSC), a naturally occurring organoselenium compound, has shown cancer chemopreventive activity against several types of cancer. Herein, the effect of MSC on the inflammatory response in lipopolysaccharide (LPS)-activated murine RAW 264.7 macrophage cells was investigated. METHODS AND RESULTS: The present results demonstrated that MSC markedly inhibited LPS-induced production of NO in a dose-dependent pattern with decreased mRNA and protein levels of inducible nitric oxide synthase (iNOS). MSC also reduced nuclear translocation of p65 and p50 subunits of nuclear factor-κB (NF-κB), a critical transcription factor necessary for iNOS expression, accompanied with downregulation of LPS-triggered NF-κB-dependent gene expression evaluating by a luciferase reporter. Inhibition of nuclear translocation by MSC might result from the prevention of the inhibitor of NF-κB from phosphorylation and consequent degradation via suppression inhibition of phosphorylation of IκB kinase α/ß. Exploring the action mechanism involved, MSC can reduce the phosphorylation/activation of mitogen-activated protein kinases (MAPKs) related to NF-κB activation induced by LPS, including p38 MAPK and c-Jun N-terminal kinase in RAW 264.7 cells. CONCLUSION: MSC might contribute to the potent anti-inflammatory effect in LPS-activated RAW 264.7 cells via downregulation of NF-κB activation and iNOS expression, suggesting that MSC may be considered as a therapeutic candidate for chronic inflammatory diseases.

3,5,3',4',5'-pentamethoxystilbene (MR-5), a synthetically methoxylated analogue of resveratrol, inhibits growth and induces G1 cell cycle arrest of human breast carcinoma MCF-7 cells.

3,5,3',4',5'-pentamethoxystilbene (MR-5) is a synthetically methoxylated analogue of resveratrol and has been suggested to have antitumor activity because of structural similarity to resveratrol. Herein, we investigate the antiproliferative effect of MR-5 in human breast cancer MCF-7 cells and demonstrate that MR-5 had a more potent inhibition on cell growth compared with resveratrol and other methoxylated derivatives. Exploring the growth-inhibitory mechanisms of MR-5, we found that it is accompanied by G1 cell cycle arrest, which coincides with a marked inhibition of G1 cell cycle regulatory proteins, including decreased cyclins (D1/D3/E) and cyclin-dependent kinases (CDK2/4/6) and increased CDK inhibitors (CKIs) such as p15, p16, p21, and p27. Furthermore, the increase in CKI levels by MR-5 resulted in a concomitant increase in their interactions of CDK4 and CDK2, along with a strong inhibition in CDK4 kinase activity and the accumulation of hypophosphorylated Rb. MR-5 also modulated some critical kinase activities related to cell cycle regulation, including Akt, mitogen-activated protein kinase (ERK1/2), p38 mitogen-activated protein kinase (p38 MAPK), and focal adhesion kinase (FAK) in MCF-7 cells. In total, our results demonstrate that MR-5 affects multiple cellular targets that contribute to its antiproliferative activity in MCF-7 cells and provide novel information for synthetic chemists to design new antitumor agents with introduction of methoxylated group(s) in the basic compound.