7099

TLR4

The endotoxin level in the portal and peripheral veins of hepatocellular carcinoma (HCC) patients is higher and lipopolysaccharide (LPS), has been reported to inhibit tumor growth. However, in this study, we found that LPS-induced Toll-like receptor 4 (TLR4) signaling was involved in tumor invasion and the molecular mechanism was investigated. The HCC cells were used to study the invasion ability of LPS-induced HCC cells and the epithelial-mesenchymal transition (EMT) in vitro. The in vitro experiments demonstrated that LPS could significantly enhance the invasive potential and induce EMT in HCC cells with TLR4 dependent. Further studies showed that LPS could directly activate JNK/MAPK signaling through TLR4 in HCC cells. Interestingly, blocking JNK/MAPK signaling significantly inhibited EMT occurrence. Our results indicate that TLR4/JNK/MAPK signaling is required for LPS-induced EMT, tumor cell invasion and metastasis, which provide molecular insights for LPS-related pathogenesis and a basis for developing new strategies against metastasis in HCC.

Our previous works showed chronic infection of Mycoplasma hyorhinis (M. hyorhinis) was associated with gastric cancer metastasis, but the mechanisms were unknown. Herein, we found M. hyorhinis induced epithelial-mesenchymal transition (EMT) in gastric cancer cell MGC803, which was counteracted by inhibitor of NF-kappaB signaling or p65 knockdown. Furthermore, we found that TLR4 associated with p37, a membrane protein of M. hyorhinis. Knock-down or inhibition of TLR4 antagonized M. hyorhinis-induced NF-kappaB signaling, EMT, and cell migration. Thus, M. hyorhinis induces EMT and promotes cell migration via TLR4-NF-kappaB signaling, which provides a clue to the pathogenesis of M. hyorhinis in gastric cancer.CI - Copyright (c) 2014 Elsevier Ireland Ltd. All rights reserved.

BACKGROUND AND AIM: epithelial-mesenchymal transition (EMT) of biliary epithelial cells (BECs) plays an important role in biliary fibrosis. This study investigated the effects of simvastatin on the lipopolysaccharide (LPS)-induced EMT and related signal pathways in BECs. METHODS: Biliary epithelial cells were exposed to LPS (2 microg/mL) or transforming growth factor beta1 (TGF-beta1) (5 ng/mL) for 5 days. The EMT was assessed by a gain of mesenchymal cell markers (vimentin, N-cadherin, slug, and Twist-1) and a loss of epithelial cell markers (E-cadherin). The effects of simvastatin on the EMT induced by LPS or TGF-beta1 were determined by the changes in the levels of EMT markers and TLR4 and in the c-Jun N-terminal kinase (JNK), p38, and nuclear factor-kappaB (NF-kappaB) signaling pathways. RESULTS: Compared with the BECs treated with LPS alone, co-treatment with simvastatin and LPS induced an increase in the expression of E-cadherin and decreases in the expression levels of mesenchymal cell markers. The LPS-induced TLR4 expression level was slightly decreased by co-treatment with simvastatin. LPS-induced BEC growth was markedly inhibited by co-treatment with simvastatin. Furthermore, pretreatment with simvastatin inhibited the LPS-induced EMT in BECs by downregulating NF-kappaB and JNK phosphorylation. The suppressive effects of simvastatin pretreatment on the induction of the EMT by TGF-beta1 were also demonstrated in H69 cells. CONCLUSIONS: Our results demonstrate that LPS or TGF-beta1 promote the EMT in BECs that that pretreatment with simvastatin inhibited the induced EMT by downregulating toll-like receptor 4 and NF-kappaB phosphorylation. This finding suggests that simvastatin can be considered a new agent for preventing biliary fibrosis associated with the EMT of BECs.CI - (c) 2015 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Toll-like receptor 4 (TLR4) activation is a key contributor to the carcinogenesis of colon cancer. Overexpression of galectin-1 (Gal-1) also correlates with increased invasive activity of colorectal cancer. Lactate production is a critical predictive factor of risk of metastasis, but the functional relationship between intracellular lactate and Gal-1 expression in TLR4-activated colon cancer remains unknown. In this study, we investigated the underlying mechanism and role of Gal-1 in metastasis and invasion of colorectal cancer (CRC) cells after TLR4 stimulation. Exposure to the TLR4 ligand lipopolysaccharide (LPS) increased expression of Gal-1, induced EMT-related cytokines, triggered the activation of glycolysis-related enzymes, and promoted lactate production. Gene silencing of TLR4 and Gal-1 in CRC cells inhibited lactate-mediated epithelial-mesenchymal transition (EMT) after TLR4 stimulation. Gal-1-mediated activation of a disintegrin and metalloproteinase 10 (ADAM10) and ADAM 17 increased the invasion activity and expression of mesenchymal characteristics in LPS-activated CRC cells. Conversely, inhibition of ADAM10 or ADAM17 effectively blocked the generation of lactate and the migration capacity of LPS-treated CRC cells. Thus, the TLR4/Gal-1 signaling pathway regulates lactate-mediated EMT processes through the activation of ADAM10 and ADAM17 in CRC cells.

BACKGROUND/AIMS: Peritoneal fibrosis is a frequent complication of peritoneal dialysis that follows inflammation. It is recognized that epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells (PMCs), plays a key role in fibrogenesis. However, the relationship between inflammatory macrophages and PMCs remains elusive. In this study, we investigated the effects of different polarized macrophages on EMT of HMrSV5 PMCs. METHODS: Monocytes were polarized to M1/M2 macrophages before being added to HMrSV5 in direct or indirect contact. Morphological changes of HMrSV5 were observed and toll-like receptors 4 (TLR4) on macrophage surfaces was detected using flow cytometry. EMT markers and intracellular signals of HMrSV5 cells were assessed using real time-PCR and WB. RESULTS: The typical epithelial cell morphology of HMrSV5 disappeared after co-culture with M1 macrophages and was accompanied by decreased E-cadherin and increased alpha-SMA, suggesting HMrSV5 undergo EMT. These effects depended on direct contact between the two cells, as indirect contact or co-culture with M2 macrophages had no effect. Intriguingly, we found TLR4 surface receptors were activated on sorted M1 cells in co-culture, and related signal adaptors, such as TRIF, were obviously upregulated. CONCLUSION: Direct contact with M1 macrophages induces EMT of PMCs, during which TRIF-dependent TLR4 signaling pathway was activated.CI - (c) 2016 The Author(s) Published by S. Karger AG, Basel.