Epithelial-to-mesenchymal Transition Of Peritoneal Mesothelial Cells Research Articles

Effect of astragaloside IV and the role of nuclear receptor RXRα in human peritoneal mesothelial cells in high glucose‑based peritoneal dialysis fluids.

Peritoneal fibrosis is a serious complication that can occur during peritoneal dialysis (PD), which is primarily caused by damage to peritoneal mesothelial cells (PMCs). The onset of peritoneal fibrosis is delayed or inhibited by promoting PMC survival and inhibiting PMC epithelial-to-mesenchymal transition (EMT). In the present study, the effect of astragaloside IV and the role of the nuclear receptor retinoid X receptor-α (RXRα) in PMCs in high glucose-based PD fluids was investigated. Human PMC HMrSV5 cells were transfected with RXRα short hairpin RNA (shRNA), or an empty vector, and then treated with PD fluids and astragaloside IV. Cell viability, apoptosis and EMT were examined using the Cell Counting Kit-8 assay and flow cytometry, and by determining the levels of caspase-3, E-cadherin and α-smooth muscle actin (α-SMA) via western blot analysis. Cell viability and apoptosis were increased, as were the levels of E-cadherin in HMrSV5 cells following treatment with PD fluid. The protein levels of α-SMA and caspase-3 were increased by treatment with PD fluid. Exposure to astragaloside IV inhibited these changes; however, astragaloside IV did not change cell viability, apoptosis, E-cadherin or α-SMA levels in HMrSV5 cells under normal conditions. Transfection of HMrSV5 cells with RXRα shRNA resulted in decreased viability and E-cadherin expression, and increased apoptosis and α-SMA levels, in HMrSV5 cells treated with PD fluids and co-treated with astragaloside IV or vehicle. These results suggested that astragaloside IV increased cell viability, and inhibited apoptosis and EMT in PMCs in PD fluids, but did not affect these properties of PMCs under normal condition. Thus, the present study suggested that RXRα is involved in maintaining viability, inhibiting apoptosis and reducing EMT of PMCs in PD fluid.

Long noncoding RNA AK089579 inhibits epithelial-to-mesenchymal transition of peritoneal mesothelial cells by competitively binding to microRNA-296-3p via DOK2 in peritoneal fibrosis.

Peritoneal fibrosis (PF) represents a well-recognized complication associated with continuous ambulatory peritoneal dialysis therapy, characterized by a reversible epithelial-to-mesenchymal transition (EMT) at the early stage. The aim of the current study was to investigate the effects linked with the long noncoding RNA (lncRNA) AK089579 on the EMT of peritoneal mesothelial cells (PMCs) as well as the associated regulatory mechanisms of AK089579 downstream of tyrosine kinase 2 (DOK2) and microRNA-296-3p (miR-296-3p). Enrichment analysis, gene intersection association analysis, and a gene-gene intersection network were initially constructed to ascertain whether AK089579 regulated the expression of DOK2 through the mediation of miR-296-3p via the Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in PF. After the PF mouse model had been constructed, the expression of the proteins associated with the JAK2/STAT3 signaling pathway and EMT and PMC migration and invasion were all determined accordingly. Based on the obtained results, AK089579 was determined to function as a competing endogenous RNA for miR-296-3p while acting to up-regulate the expression of DOK2, which is a target gene of miR-296-3p. AK089579 was detected to confer an inhibitory effect on the activation of the JAK2/STAT3 signaling pathway, whereby the migration and invasion of PMCs among the mice models were suppressed. Meanwhile, up-regulated miR-296-3p and down-regulated DOK2 produced contrasting effects when compared with the aforementioned findings. Treatment with wp10066, a JAK2/STAS3 signaling pathway inhibitor, was shown to reverse the effects exerted by up-regulated miR-296-3p. Taken together, the central findings of the current study present evidence highlighting the capability of the lncRNA AK089579 to bind competitively to miR-296-3p and indirectly enhance the expression of DOK2, which in turn suppresses the activation of the JAK2/STAT3 signaling pathway, whereby the EMT, migration, and invasion of PMCs was inhibited in PF.-Zhang, X. W., Wang, L., Ding, H. Long noncoding RNA AK089579 inhibits epithelial-to-mesenchymal transition of peritoneal mesothelial cells by competitively binding to microRNA-296-3p via DOK2 in peritoneal fibrosis.

Molecular mechanisms of melatonin in the reversal of LPS-induced EMT in peritoneal mesothelial cells.

Peritoneal dialysis (PD)-associated peritoneal fibrosis is a serious complication in patients with chronic renal failure on dialysis maintenance. Studies have shown that patients on long‑term PD have chronic inflammation. The epithelial-to-mesenchymal transition (EMT) induced by inflammation is a major cause of peritoneal fibrosis and dysfunction. As a potent antioxidant property, melatonin has an antifibrotic effect. The present study investigated the effects of melatonin on lipopolysaccharide (LPS)‑induced EMT and examined the molecular mechanisms in peritoneal mesothelial cells using western blotting, reverse transcription‑polymerase chain reaction and immunofluorescence staining. The results of the study found that melatonin inhibited LPS‑induced morphological changes, decreased the expression of LPS-induced markers of EMT, including vimentin and α‑smooth muscle actin, and increased the expression of E‑cadherin. In addition, it was found that the action of melatonin was mediated through the inactivation of the Toll‑like receptor (TLR)4/c‑Jun N‑terminal kinase and TLR4/nuclear factor‑κB‑Snail signaling pathways. Thus, these data provided novel insight into the mechanisms underlying the function of melatonin in peritoneal mesothelial cells during the processes of EMT, and may provide a theoretical basis for the treatment of peritoneal fibrosis.

Heat shock protein70 protects rat peritoneal mesothelial cells from advanced glycation end-products-induced epithelial-to-mesenchymal transition through mitogen‑activated protein kinases/extracellular signal-regulated kinases and transforming growth factor-β/Smad pathways.

Epithelial‑to‑mesenchymal transition (EMT) may result in damage to the peritoneum and the development of fibrosis in peritoneal mesothelial cells (PMCs). However, the mechanism underlying EMT in peritoneal mesothelial cells is not well understood. Heat shock proteins (HSPs) were initially identified as proteins that are expressed following exposure of cells to environmental stress. However, their function in the development of EMT in PMCs remains to be fully elucidated. In the present study, the effect of HSP70 on advanced glycation end‑products (AGEs)‑induced EMT in peritoneal mesothelial cells was investigated by overexpression of this protein using a plasmid and knockdown of HSP70 using small interfering RNA. In addition, the underlying molecular mechanisms were explored. The results demonstrated that AGEs activated changes associated with EMT, including the loss of E‑cadherin and the increase in α‑smooth muscle actin. Furthermore, AGEs also induced the upregulation of HSP70, which led to the partial inhibition of EMT in PMCs. HSP70 inhibits EMT by modulating transforming growth factor‑β (TGF‑β)/Smad expression and the mitogen‑activated protein kinases (MAPK)/extracellular signal‑regulated kinases (ERK) signaling pathways. The findings suggested that HSP70 augments the cellular defense capacity through inhibition of TGF‑β/Smad and MAPK/ERK signaling pathways, thereby protecting PMCs from AGEs‑induced EMT.

HSP70 inhibits high glucose-induced Smad3 activation and attenuates epithelial-to-mesenchymal transition of peritoneal mesothelial cells.

Heat shock proteins (HSPs) are molecular chaperones that were initially identified as proteins expressed following exposure of cells to environmental stress. However, the function of HSPs in epithelial‑to‑mesenchymal transition (EMT) of peritoneal mesothelial cells remains unknown. In the present study, the regulation of HSPs and their function in cell EMT, particularly in rat peritoneal mesothelial cells (RPMCs), and the surrounding glucose concentrations and the molecular mechanism involved were investigated. This study explored the effect of HSP70 on high glucose (HG)-induced EMT by overexpression and small interfering RNA (siRNA) knockdown of HSP70, as well as the underlying molecular mechanisms. It was found that HSP70 inhibits HG-induced EMT by modulating Smad expression and activation. HSP70 overexpression inhibited phosphorylation and nuclear translocation of p-Smad3 and p-Smad4, while siRNA of HSP70 enhanced HG‑induced Smad3 and Smad4 phosphorylation and EMT. Furthermore, HSP70 suppressed EMT by inhibiting the generation of reactive oxygen species (ROS) induced by HG. In conclusion, HSP70 inhibits EMT of peritoneal mesothelial cells primarily by exerting domain‑specific effects on Smad3 and Smad4 activation and reducing the release of ROS. HSP70 may be a novel therapeutic target for peritoneal dialysis patients with peritoneal fibrosis.

Paricalcitol Ameliorates Epithelial-to-Mesenchymal Transition in the Peritoneal Mesothelium

Background: The purpose of the present study was to examine the effectiveness of paricalcitol for the prevention of epithelial-to-mesenchymal transition (EMT). Materials and Methods: Human peritoneal mesothelial cells (HPMCs) were cultured in media containing transforming growth factor β₁ (TGF-β₁) with or without paricalcitol. Forty-two male Sprague-Dawley rats were divided into three groups. In the control group, the catheter was inserted but no dialysate was infused. The peritoneal dialysis (PD) group was infused with a conventional 4.25% dialysis solution. The paricalcitol group was infused with 4.25% dialysis solution and cotreated with paricalcitol. Results: Exposure of HPMCs to TGF-β₁ decreased the protein level of the epithelial cell marker and increased the expression levels of the mesenchymal markers. Cotreatment with paricalcitol increased the protein levels of the epithelial cell marker and decreased those of mesenchymal markers compared with their levels in cells treated with TGF-β₁ alone. Exposure of HPMCs to TGF-β₁ significantly increased the phosphorylation of Smad2 and Smad3. Cotreatment with paricalcitol significantly decreased the phosphorylation of Smad2 and Smad3 compared with that of cells treated with TGF-β₁ alone. After 8 weeks of experimental PD in rats, the thickness of the peritoneal membrane in the PD group was significantly increased compared with that of the control group. Cotreatment with paricalcitol decreased peritoneal thickness. Conclusion: The present study showed that paricalcitol attenuates the TGF-β₁-induced EMT in peritoneal mesothelial cells. We suggest that paricalcitol may preserve peritoneal mesothelial cells during PD and could thus be of value for the success of long-term PD.

Zinc Transporter 7 Induced by High Glucose Attenuates Epithelial-to-Mesenchymal Transition of Peritoneal Mesothelial Cells

Zinc (Zn) is an essential micronutrient and cytoprotectant involved in preventing many types of epithelial-to-mesenchymal transition (EMT)-driven fibrosis in vivo. The zinc-transporter family SLC30A (ZnT) is a pivotal factor in the regulation of Zn homeostasis. However, its function in EMT in peritoneal mesothelial cells (PMCs) remains unknown. This study explored the regulation of zinc transporters and the role they play in cell EMT, particularly in rat peritoneal mesothelial cells (RPMCs), surrounding glucose concentrations and the molecular mechanism involved. The effects of high glucose (HG) on zinc transporter gene expression were measured in RPMCs by real-time PCR. We explored ZnT7 (Slc30A7): the effect of ZnT7 over-expression and siRNA-mediated knock-down on HG-induced EMT was investigated as well as the underlying molecular mechanisms. Over-expression of ZnT7 resulted in significantly inhibited HG-induced EMT in RPMCs, while inhibition of ZnT7 expression using a considerable siRNA-mediated knock-down of RPMCs increased the levels of EMT. Furthermore, over-expression of ZnT7 is accompanied by down-regulation of TGF-β/Smad pathway, phospho-Smad3,4 expression levels. The finding suggests that the zinc-transporting system in RPMCs is influenced by the exposure to HG. The ZnT7 may account for the inhibition of HG-induced EMT in RPMCs, likely through targeting TGF-β/Smad signaling.

Connective tissue growth factor is a positive regulator of epithelial–mesenchymal transition and promotes the adhesion with gastric cancer cells in human peritoneal mesothelial cells

Connective tissue growth factor (CTGF) is involved in human cancer development and progression. Epithelial to mesenchymal transition (EMT) plays an important role in many biological processes. In this study, we wished to investigate the role of CTGF in EMT of peritoneal mesothelial cells and the effects of CTGF on adhesion of gastric cancer cells to mesothelial cells. Human peritoneal mesothelial cells (HPMCs) were cultured with TGF-β1 or various concentrations of CTGF for different time. The EMT process was monitored by morphology. Real-time RT-PCR and Western blot were used to evaluate the expression of vimentin, α-SMA , E-cadherin and β-catenin. RNA interference was used to achieve selective and specific knockdown of CTGF. We demonstrated that CTGF induced EMT of mesothelial cells in a dose- and time-dependent manner. HPMCs were exposed to TGF-β1 also underwent EMT which was associated with the induction of CTGF expression. Transfection with CTGF siRNA was able to reverse the EMT partially after treatment of TGF-β1. Moreover, the induced EMT of HPMCs was associated with an increased adhesion of gastric cancer cells to mesothelial cells. These findings suggest that CTGF is not only an important mediator but a potent activator of EMT in peritoneal mesothelial cells, which in turn promotes gastric cancer cell adhesion to peritoneum.