HIF-1α regulates EMT via the Snail and β-catenin pathways in paraquat poisoning-induced early pulmonary fibrosis

Microbubble-Mediated Cavitation Promotes Apoptosis and Suppresses Invasion in AsPC-1 Cells

The aim of this study was to identify the potential and mechanisms of microbubble-mediated cavitation in promoting apoptosis and suppressing invasion in cancer cells. AsPC-1 cells were used and divided into four groups: control group, microbubble-only (MB) group, ultrasound-only (US) group and ultrasound plus microbubble (US + MB) group. Pulse ultrasound was used at a frequency of 360 kHz and a SPPA (spatial peak, pulse average) intensity of 1.4 W/cm² for 1 min (duty rate = 50%). Then cells in the four groups were cultured for 24 h. Cell Counting Kit‑8 (Biosharp, Hefei, Anhui, China) revealed decreased cell viability in the US + MB group. Western blot confirmed that there were increased cleaved caspase‑3 and Bcl-2-associated X protein levels and decreased B‑cell lymphoma‑2 (Bcl-2) levels, as well as increased intracellular calcium ions and downregulated cleaved caspase-8, in the US + MB group. With respect to proliferation, cells in the US + MB group had lower expression of Ki67 and the weakened colony formation ability. The transwell invasion assay revealed that invasion ability could be decreased in AsPC-1 cells in the US + MB group. Further, it was found that cells in the US + MB group had lower levels of hypoxia-inducible factor-1α (HIF-1α) and vimentin and higher levels of E-cadherin compared with the other three groups. Finally, the US + MB cells had less invadopodium formation. In conclusion, these results suggest that microbubble-mediated cavitation promotes apoptosis and suppresses invasion in AsPC-1 cells.

Connexin 43 prevents the progression of diabetic renal tubulointerstitial fibrosis by regulating the SIRT1-HIF-1α signaling pathway

Hyperglycemia-induced renal epithelial-to-mesenchymal transition (EMT) is a key pathological factor in diabetic renal tubulointerstitial fibrosis (RIF). Our previous studies have shown that connexin 43 (Cx43) activation attenuated the development of diabetic renal fibrosis. However, whether Cx43 regulates the EMT of renal tubular epithelial cells (TECs) and the pathological process of RIF under the diabetic conditions remains to be elucidated. In the present study, we identified that Cx43 protein expression was down-regulated in the kidney tissues of db/db mice as well as in high glucose (HG)-induced NRK-52E cells. Overexpression of Cx43 improved renal function in db/db spontaneous diabetic model mice, increased SIRT1 levels, decreased hypoxia-inducible factor (HIF)-1α expression, and reduced production of EMT markers and extracellular matrix (ECM) components. Additionally, Cx43 overexpression inhibited the EMT process and reduced the expression of ECM components such as fibronectin (FN), Collagen I, and Collagen IV in HG-induced NRK-52E cells, whereas Cx43 deficiency had the opposite effects. Mechanistically, Cx43 in a carboxyl-terminal signal transduction-dependent manner could up-regulate SIRT1 expression and enhance SIRT1-dependent deacetylation of HIF-1α to reduce HIF-1α activity, which eventually ameliorated renal EMT and diabetic RIF. Our study indicates the essential role of Cx43 in regulating renal EMT and diabetic RIF via regulating the SIRT1-HIF-1α signaling pathway and provides an experimental basis for Cx43 as a potential target for diabetic nephropathy (DN).

miR‑212 promotes renal interstitial fibrosis by inhibiting hypoxia‑inducible factor 1‑α inhibitor

Renal interstitial fibrosis is one of the common causes, and a major pathological basis for the development of various types of chronic progressive renal to end-stage renal diseases. Therefore, it is important to clarify the underlying mechanisms of disease progression in order to develop effective strategies for the treatment and prevention of these pathologies. The aim of the present study was to investigate the association between microRNA (miR)-212 expression and the development of renal interstitial fibrosis, as well as analyzing the role of miR-212 in the disease. The expression of miR-212 was significantly increased in the peripheral blood of patients with renal interstitial fibrosis and in the kidney tissues of unilateral ureteral obstruction (UUO) mice. Angiotensin (Ang) II, TGF-β1 and hypoxia were found to increase the expression of miR-212 and α smooth muscle actin (α-SMA) in NRK49F cells. Ang II stimulation induced the expression of miR-212 and α-SMA in NRK49F cells, while transfection of miR-212 mimics further upregulated the expression of α-SMA. miR-212 was also revealed to target hypoxia-inducible factor 1α inhibitor (HIF1AN) and to upregulate the expression of hypoxia-inducible factor 1α, α-SMA, connective tissue growth factor, collagen α-1(I) chain and collagen α-1(III) chain, whereas HIF1AN overexpression reversed the regulatory effects of miR-212. In UUO mice, miR-212 overexpression promoted the progression of renal interstitial fibrosis, whereas inhibiting miR-212 resulted in the opposite effect. These results indicated that high expression of miR-212 was closely associated with the occurrence of renal interstitial fibrosis, and that miR-212 may promote its development by targeting HIF1AN.

Role of epithelial-to-mesenchymal transition in the pulmonary fibrosis induced by paraquat in rats

BACKGROUND

This study aims to explore the characteristics of the epithelial-to-mesenchymal transition (EMT) process and its underlying molecular mechanisms in the period of paraquat (PQ)-induced pulmonary fibrosis (PF).

METHODS

Picrosirius red staining and collagen volume fraction were utilized to evaluate the pathological changes of PQ-induced PF in rats. Immunohistochemistry, Western blot, and real-time reverse transcriptase-polymerase chain reaction (RT-PCR) were used to measure the protein and gene expression of EMT markers, EMT-associated transcription factors, and regulators of EMT-related pathways, respectively.

RESULTS

The collagen deposition in the alveolar septum and increased PF markers were characteristics of pathological changes in PQ-induced PF, reached a peak on day 14 after PQ poisoning, and then decreased on day 21. The protein and gene expression of the fibrosis marker, EMT markers, transcription factors, and regulators of EMT-related signaling pathways significantly increased at different time points after PQ poisoning compared with corresponding controls (P<0.05), and most of them reached a peak on day 14, followed by a decrease on day 21. The gene expression of EMT markers was significantly correlated with PF markers, transcription factors, and regulators of EMT-related signaling pathways (P<0.05). The mRNA expression of transcription factors was significantly correlated with that of TGF-β1 and Smad2 (P<0.05 or P<0.01), instead of Wnt2 and β-catenin (P>0.05).

CONCLUSIONS

EMT process plays a role in the PQ-induced PF, in which most PF and EMT markers have a peak phenomenon, and its underlying molecular mechanisms might be determined by further studies.

S100A2 Silencing Relieves Epithelial-Mesenchymal Transition in Pulmonary Fibrosis by Inhibiting the Wnt/β-Catenin Signaling Pathway

Pulmonary fibrosis (PF) is a progressive and lethal disease with poor prognosis. S100A2 plays an important role in the progression of cancer. However, the role of S100A2 in PF has not yet been reported. In this study, we explored the potential role of S100A2 in PF and its potential molecular mechanisms. Increased expression of S100A2 was first observed in lung tissues of PF patients. We found that downregulation of S100A2 inhibited the transforming growth factor-β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) in A549 cells. Mechanically, TGF-β1 upregulated β-catenin and the phosphorylation of glycogen synthase kinase-3β, which was blocked by silencing S100A2 in vitro. Furthermore, lithium chloride (activator of the Wnt/β-catenin signaling pathway) effectively rescued S100A2 knockdown-mediated inhibition of EMT in PF. In conclusion, these findings demonstrate that downregulation of S100A2 alleviated PF through inhibiting EMT. S100A2 is a promising potential target for further understanding the mechanism and developing a strategy for the treatment of PF and other EMT-associated diseases.

Neddylation blockade induces HIF-1α driven cancer cell migration via upregulation of ZEB1

Neddylation is a process by which NEDD8 is covalently conjugated to target proteins by sequential enzymatic reaction. Its role in cancer cell migration has only been recently acknowledged. Previously in cancer cell migration, the epithelial to mesenchymal transition (EMT) process has been well-known to play an important role in both invasion and metastasis by promoting mesenchymal phenotype in epithelial cells. However, the role of neddylation in the EMT process and its mechanistic details are yet to be elucidated. We recently reported that neddylation plays a crucial role in cancer cell migration through the PI3K-Akt pathway. Here, we report that inhibiting neddylation activates the hypoxia-inducible factor 1α (HIF-1α) through the PI3K-Akt pathway, which eventually regulates the EMT-activator ZEB1 (zinc finger E-box binding homeobox 1) in various cancer cell lines. As induction of HIF-1α is known to deteriorate the state of cancer and EMT process is one of the hallmarks of metastasis in cancer, our findings uncover the role of neddylation between HIF-1α and ZEB1.

MiR-200a inversely correlates with Hedgehog and TGF-β canonical/non-canonical trajectories to orchestrate the anti-fibrotic effect of Tadalafil in a bleomycin-induced pulmonary fibrosis model

Few reports have documented the ability of phosphodiesterase-5 inhibitors (PDE-5-Is) to ameliorate idiopathic pulmonary fibrosis (IPF) mainly by their anti-inflammatory/antioxidant capacities, without unveiling the possible molecular mechanisms involved. Because of the recent role of miR-200 family and Sonic Hedgehog (SHH) trajectory in IPF, we have studied their impact on the anti-fibrotic potential of tadalafil against bleomycin-induced pulmonary fibrosis. Animals were allocated into normal-control, bleomycin-fibrotic control, and bleomycin post-treated with tadalafil or dexamethasone, as the reference drug. On the molecular level, tadalafil has reverted the bleomycin effect on all the assessed parameters. Tadalafil upregulated the gene expression of miR-200a, but decreased the smoothened (SMO) and the transcription factors glioma-associated oncogene homolog (Gli-1, Gli-2), members of SHH pathway. Additionally, tadalafil ebbed transforming growth factor (TGF)-β, its canonical (SMAD-3/alpha smooth muscle actin [α-SMA] and Snail), and non-canonical (p-Akt/p-Forkhead box O3 (FOXO3) a) pathways. Besides, a strong negative correlation between miR-200a and the analyzed pathways was proved. The effect of tadalafil was further confirmed by the improved lung structure and the reduced Ashcroft score/collagen deposition. The results were comparable to that of dexamethasone. In conclusion, our study has highlighted the involvement of miR-200a in the anti-fibrotic effect of tadalafil with the inhibition of SHH hub and the pro-fibrotic pathways (TGF-β/ SMAD-3/α-SMA, Snail and p-AKT/p-FOXO3a). Potential anti-fibrotic effect of tadalafil. Modulation of miR200a/SHH/canonical and non-canonical TGF-β trajectories. → : stimulatory effect; ┴: inhibitory effect.

Signaling pathways promoting epithelial mesenchymal transition in oral submucous fibrosis and oral squamous cell carcinoma

Epithelial-mesenchymal transition (EMT) is a critical process that occurs during the embryonic development, wound healing, organ fibrosis and the onset of malignancy. Emerging evidence suggests that the EMT is involved in the invasion and metastasis of cancers. The inflammatory reaction antecedent to fibrosis in the onset of oral submucous fibrosis (OSF) and the role of EMT in its malignant transformation indicates a hitherto unexplored involvement of EMT. This review focuses on the role of EMT markers which are regulators of the EMT mediated complex network of molecular mechanisms involved in the pathogenesis of OSF and OSCC. Further the gene enrichment analysis and pathway analysis supports the association of the upregulated and downregulated genes in various EMT regulating pathways.

Paraquat induces pulmonary fibrosis through Wnt/β-catenin signaling pathway and myofibroblast differentiation

Paraquat (PQ) poisoning-induced pulmonary fibrosis always results in fatal harm to patients. Our study aimed to investigate the functions of the Wnt/β-catenin pathway in PQ-induced pulmonary fibrosis. By comparing the proteomic profiles of rat lung tissues using protein array in the absence or presence of PQ, the Wnt/β-catenin signaling, as a fibrosis-related pathway, was discovered to be profoundly activated by PQ. The protein levels of Wnt/β-catenin signaling components including MMP-2, β-catenin, Wnt3a, Wnt10b, Cyclin D1, and WISP1 were increased in PQ-treated rat lung tissues. Surprisingly, PQ was found to be able to promote lung epithelial cells and fibroblasts differentiating into myofibroblasts by activating Wnt/β-catenin signaling pathway. Dickkopf-1 (DKK1), an antagonist of Wnt/β-catenin signaling pathway, could inhibit the myofibroblast differentiation and attenuate PQ-induced pulmonary fibrogenesis in vitro and in vivo. The expression levels of fibroblasts markers Vimentin, α-smooth muscle actin (α-SMA) and Collagen I was detected and found to be increased when PQ treated and restored with additional DKK1 treatment. In summary, these assays indicated that Wnt/β-catenin signaling pathway played a regulatory role in the differentiation of lung epithelial cells and fibroblasts, and the pathogenesis of pulmonary fibrosis related to PQ. Inhibition of the Wnt/β-catenin signaling pathway may be investigated further as a potential fibrosis suppressor for pulmonary fibrosis therapy.

The MUC5B Mucin Is Involved in Paraquat-Induced Lung Inflammation

Objective

Paraquat (PQ), a widely used toxic herbicide, induces lung inflammation through mechanisms that remain incompletely understood. In a previous study, we found that the plasma MUC5B mucin level was implicated in PQ poisoning in patients. Here, we hypothesize that MUC5B is a critical mediator in PQ-induced cell inflammation.

Methods

A mouse model of PQ-induced lung injury was used to examine the MUC5B expression level. A549 cells (alveolar epithelial cells line) were exposed to PQ in dose-dependent and time-dependent manners. Cell viability was detected by CCK-8 assays. The expression levels of MUC5B were examined by dot blot enzyme-linked immunosorbent assay (ELISA) and RT-qPCR. Western blotting was used to detect the levels of proteins in the MAPK and NF-κB pathways. Inflammatory factors in the cell culture medium were measured by ELISA. NF-κB and MAPK pathway inhibitors and MUC5B siRNA (siMUC5B) were used to determine the function of MUC5B. Finally, N-acetyl-cysteine (NAC) was added and its regulatory effect on the MAPK-NF-κB-MUC5B pathway was examined in PQ-induced cell inflammation.

Results

MUC5B was significantly upregulated accompanying the increases in TNF-α and IL-6 secretion following PQ treatment in mouse and also in A549 cells after treatment with 50 μM PQ at 24 hours. Furthermore, MAPK and NF-κB pathway inhibitors could dramatically decrease the expression of MUC5B and the secretion of TNF-α and IL-6. Importantly, siMUC5B could significantly attenuate the secretion of TNF-α and IL-6 induced by PQ. As expected, the addition of NAC efficiently suppresses the TNF-α and IL-6 secretion stimulated from PQ and also downregulated ERK, JNK, and p65 phosphorylation (ERK/JNK MAPK and NF-κB pathways) as well as MUC5B expression.

Conclusion

Our findings suggest that MUC5B participates in the process of PQ-induced cell inflammation and is downstream of the NF-κB and MAPK pathways. NAC can attenuate PQ-induced cell inflammation at least in part by suppressing the MAPK-NF-κB-MUC5B pathway. These results nominate MUC5B as a new biomarker and therapeutic target for PQ-induced lung inflammation.

Plantamajoside inhibits the proliferation and epithelial-to-mesenchymal transition in hepatocellular carcinoma cells via modulating hypoxia-inducible factor-1α-dependent gene expression

As a potential antitumor herbal medicine, plantamajoside (PMS) benefits the treatment of many human malignances. However, the role of PMS in the progression of hepatocellular carcinoma (HCC) and the related molecular mechanisms is still unknown. Here, we proved that the cell viabilities of HepG2 cells were gradually decreased with the increasing concentrations of CoCl₂ and/or PMS via cell counting kit-8 assay. Meanwhile, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and western blot assays were used to further confirm that PMS inhibited the CoCl₂ -induced cell proliferation in HepG2 cells via suppressing the Ki67 and proliferating cell nuclear antigen expressions. We also performed wound-healing and transwell assays and demonstrated that PMS inhibited CoCl₂ -induced migration and invasion in HepG2 cells via suppressing the epithelial-mesenchymal transition (EMT) process. In addition, the use of 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole further proved that PMS inhibited the malignant biological behaviors of HepG2 cells under hypoxic condition by suppressing the hypoxia-inducible factor-1α (HIF-1α) expression. Besides, we further confirmed that PMS suppressed the growth and metastasis of implanted tumors in vivo. Given that PMS suppressed the proliferation and EMT induced by CoCl₂ in HCC cells via downregulating HIF-1α signaling pathway, we provided evidence that PMS might be a novel anti-cancer drug for HCC treatment.

Taurocholic acid inhibits features of age-related macular degeneration in vitro

Previous metabolomics studies from our lab found altered plasma levels of bile acids in patients with age-related macular degeneration (AMD) compared to controls. In this study, we investigated the ability of the bile acid taurocholic acid (TCA) to inhibit features of AMD modeled in vitro. Paraquat was used to induce oxidative stress in HRPEpiC primary retinal pigment epithelial (RPE) cells. Cells were treated with 300 μM paraquat alone or with TCA (10, 50, 100, 200, or 500 μM). RPE tight junction integrity was assessed via ZO-1 immunofluorescence and transepithelial electrical resistance (TEER) measurements. RF/6A macaque choroidal endothelial cells were treated with 100 ng/mL vascular endothelial growth factor (VEGF) to induce angiogenesis. The effect of TCA on VEGF-induced angiogenesis was evaluated with cell proliferation, cell migration, and tube formation assays. Addition of TCA at 100 (P = 8.6 × 10^-4), 200 (P = 0.0035), and 500 (P = 2.1 × 10^-4) μM resulted in significant preservation of TEER in paraquat treated cells. In RF/6A cells, TCA did not significantly affect VEGF-induced cell proliferation. VEGF-induced migration of RF/6A cells was significantly inhibited at TCA concentrations of 100 (P = 0.010), 200 (P = 0.023) and 500 (P = 0.0049) μM. VEGF-induced tube formation was significantly inhibited when treated with 200 (P = 0.014) and 500 (P = 7.1 × 10^-4) μM TCA. In vitro, TCA promoted RPE cell integrity and diminished VEGF-induced choroidal endothelial cell migration and tube formation. This suggests that TCA may have protective effects against both degenerative and neovascular AMD.

Inhibition of HIF1A-AS1 impedes the arecoline-induced migration activity of human oral mucosal fibroblasts

Long non-coding RNA hypoxia-inducible factor 1α-antisense RNA 1 (HIF1A-AS1) has been known to participate in various types of malignancies, but its role in the development of precancerous oral submucous fibrosis (OSF) has not been investigated. In the current study, we first observed the aberrant upregulation of HIF1A-AS1 in OSF tissues and fibrotic buccal mucosal fibroblasts (fBMFs) isolated from OSF specimens. Next, we demonstrated that administration of arecoline, a natural alkaloid that is found in areca nut, induced the elevation of HIF1A-AS1 in BMFs. This finding showed that the habit of areca nut chewing may lead to an increase of HIF1A-AS1 in oral mucosa. Moreover, we found that knockdown of HIF1A-AS1 hindered the arecoline-stimulated migration capacity in BMFs, suggesting HIF1A-AS1 was critical to the transdifferentiation of BMFs into myofibroblasts. Altogether, our results demonstrated that overexpression of HIF1A-AS1 in OSF tissues may result from the use of areca nut and lead to activation of BMFs, which contribute to the progression of OSF.

MiR-155-5p promotes oral cancer progression by targeting chromatin remodeling gene ARID2

BACKGROUND

Dysregulation of miRNAs is associated with aberrant migration and invasion by suppressing relevant target genes in multiple cancers, including oral squamous cell carcinoma (OSCC). Accumulating evidence suggests that microRNA-155-5p is involved in carcinogenesis and tumor progression. However, the exact function and molecular mechanism of miR-155-5p in OSCC remain unclear. This study aimed to investigate the function of miR-155-5p and the molecular mechanisms underlying the influencing progression of OSCC.

METHODS

The miR-155-5p expression level in the OSCC tissues and oral cancer cell lines were determined by the qRT-PCR. Gain-of-function and knockdown approach were used to examine the effect of miR-155-5p on cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of OSCC. The luciferase reporter assay was applied to confirm the AT-rich interactive domain 2 (ARID2) as a potential target of miR-155-5p, and the rescue experiment was employed to verify the roles of the miRNA-155-5p-ARID2 axis in OSCC progression. Immunohistochemical staining was used to detect ARID2 expression in another cohort sample tissues from OSCC patients.

RESULTS

MiR-155-5p was significantly upregulated in OSCC tissues and cell lines. The miR-155-5p expression level was positively correlated with tumor size, TNM stage, histological grade and lymph node metastasis of OSCC patients. Functional assays demonstrated that miR-155-5p enhanced OSCC cell proliferation, migration and invasion. Mechanistically, ARID2 was identified as a direct target and functional effector of miR-155-5p in OSCC. Furthermore, ARID2 overexpression could rescue the aberrant biological function by overexpressed miR-155-5p in OSCC cells. Notably, we showed that ARID2 could be used as an independent prognosis factor in OSCC.

CONCLUSIONS

Our results suggest that miR-155-5p facilitates tumor progression of OSCC by targeting ARID2, and miR-155-5p-ARID2 axis may be a potential therapeutic target of OSCC.

The Role of MicroRNAs upon Epithelial-to-Mesenchymal Transition in Inflammatory Bowel Disease

Increasing evidence suggest the significance of inflammation in the progression of cancer, for example the development of colorectal cancer in Inflammatory Bowel Disease (IBD) patients. Long-lasting inflammation in the gastrointestinal tract causes serious systemic complications and breaks the homeostasis of the intestine, where the altered expression of regulatory genes and miRNAs trigger malignant transformations. Several steps lead from acute inflammation to malignancies: epithelial-to-mesenchymal transition (EMT) and inhibitory microRNAs (miRNAs) are known factors during multistage carcinogenesis and IBD pathogenesis. In this review, we outline the interactions between EMT components and miRNAs that may affect cancer development during IBD.

HIF-1α is a key mediator of the lung inflammatory potential of lithium-ion battery particles

Background

Li-ion batteries (LIB) are increasingly used worldwide. They are made of low solubility micrometric particles, implying a potential for inhalation toxicity in occupational settings and possibly for consumers. LiCoO₂ (LCO), one of the most used cathode material, induces inflammatory and fibrotic lung responses in mice. LCO also stabilizes hypoxia-inducible factor (HIF) -1α, a factor implicated in inflammation, fibrosis and carcinogenicity. Here, we investigated the role of cobalt, nickel and HIF-1α as determinants of toxicity, and evaluated their predictive value for the lung toxicity of LIB particles in in vitro assays.

Results

By testing a set of 5 selected LIB particles (LCO, LiNiMnCoO₂, LiNiCoAlO₂) with different cobalt and nickel contents, we found a positive correlation between their in vivo lung inflammatory activity, and (i) Co and Ni particle content and their bioaccessibility and (ii) the stabilization of HIF-1α in the lung. Inhibition of HIF-1α with chetomin or PX-478 blunted the lung inflammatory response to LCO in mice. In IL-1β deficient mice, HIF-1α was the upstream signal of the inflammatory lung response to LCO. In vitro, the level of HIF-1α stabilization induced by LIB particles in BEAS-2B cells correlated with the intensity of lung inflammation induced by the same particles in vivo.

Conclusions

We conclude that HIF-1α, stabilized in lung cells by released Co and Ni ions, is a mechanism-based biomarker of lung inflammatory responses induced by LIB particles containing Co/Ni. Documenting the Co/Ni content of LIB particles, their bioaccessibility and their capacity to stabilize HIF-1α in vitro can be used to predict the lung inflammatory potential of LIB particles.

Electronic supplementary material

The online version of this article (10.1186/s12989-019-0319-z) contains supplementary material, which is available to authorized users.

Inhibitor of growth 4 (ING4) inhibits hypoxia-induced EMT by decreasing HIF-1α and snail in HK2 cells

Renal fibrosis is a common mechanism that leads to all kidney diseases and Epithelial-mesenchymal transition (EMT) is considered as one of the potential mechanisms of renal fibrosis. Inhibitor of growth 4 (ING4) was reported to involve in several diseases; especially it was negatively correlated with lung fibrogenesis parameters. However, the role of ING4 and underlying mechanisms in EMT are still unknown. In this study, we used a UUO rat model to mimic renal fibrosis, which was examined by Masson and HE staining analysis. To explore the effects of ING4 on hypoxia-induced EMT, HK2 cells were treated with hypoxia to induce EMT and ING4 was over-expressed in hypoxia-treated HK2 cells by transfection of pEGFP-N1-ING4. MTT assay was used to describe the cell viability of HK2 cells under the hypoxic condition. The expression levels of ING4, hypoxia-inducible factor-1α (HIF-1α), and EMT markers (E-cadherin, N-cadherin and vimentin) were examined in vivo and in vitro by western blot, qRT-PCR, immunohistochemical staining or Immunofluorescence. Our results showed that, in a UUO rat model, ING4 was decreased and EMT was developed with reduction in E-cadherin and increase in N-cadherin and vimentin, suggesting a significant association between ING4 expression and EMT. Under hypoxia, E-cadherin was down-regulated and N-cadherin and vimentin were up-regulated, indicating that hypoxia induced EMT in HK2 cells. Nonetheless, changes in the expression of EMT biomarkers were inhibited by over-expression of ING4. Moreover, over-expressing ING4 decreased the expression of HIF-1α and snail in HK2 cells. These findings suggest that ING4 may inhibit hypoxia-induced EMT via decreasing HIF-1α and snail in HK2 cells, indicating the potential of ING4 as a therapeutic target for renal fibrosis.

Akt and Notch pathways mediate polyhexamethylene guanidine phosphate-induced epithelial-mesenchymal transition via ZEB2

Polyhexamethylene guanidine phosphate (PHMG-p), an antimicrobial additive, was used as a humidifier disinfectant in Korea and caused severe lung injuries, including lung fibrosis, in hundreds of victims. As PHMG-p-induced lung fibrosis is different from that induced by known fibrogenic agents such as bleomycin, it is important to understand the molecular mechanisms underlying this effect. A recent study showed that epithelial-mesenchymal transition (EMT) could play key roles in PHMG-p-induced pulmonary fibrosis. Therefore, we aimed to characterize the molecular mechanisms associated with PHMG-p-induced EMT. We observed EMT, macrophage infiltration, and fibrosis in mouse lung tissues after intratracheal instillation of PHMG-p. Furthermore, PHMG-p-induced EMT was observed in A549 cells by the evaluation of cell morphology and quantitation of mRNA and protein expression. The use of EMT inhibitors revealed that PHMG-p induced EMT through the activation of Akt and Notch signaling. Moreover, the transcription factor ZEB2 was observed in PHMG-p-treated A549 cells and mouse lungs. The results indicated that upstream regulators, including Akt and Notch 1, acted as intracellular effectors that triggered ZEB2 expression after exposure to PHMG-p. Attenuation of PHMG-p-induced EMT following inhibition or silencing of Akt and Notch signaling or ZEB2 implied that PHMG-p-induced EMT was a result of Akt, Notch, and ZEB2 activation. Our findings showed that PHMG-p induced EMT through Akt/Notch signaling pathways and that ZEB2 played an important role in PHMG-p-induced lung toxicity. This study will help to understand the mechanisms of action of PHMG-p associated with lung fibrogenesis.

Curcumin suppresses intestinal microvascular endothelial cells invasion and angiogenesis induced by activated platelets

The present study investigated the effects and mechanism by which curcumin suppresses intestinal microvascular endothelial cells (INMECs) invasion and angiogenesis induced by activated platelets. INMECs were obtained from healthy rats, and divided into five groups: Control, platelets, platelets +2.5 µM curcumin, platelets +5.0 µM curcumin and platelets +10.0 µM curcumin. Curcumin toxicity was determined and vascular endothelial growth factor (VEGF) concentrations of the five groups were measured using ELISA. The branch point numbers were measured using a capillary tube formation experiment, invasion cell numbers were evaluated with the Transwell assay, relative protein expression levels were measured with western blot assay and immunofluorescence staining of the nucleus. The 2.5, 5 and 10 µM curcumin concentrations were found to be suitable for INMECs. Curcumin significantly downregulated VEGF concentration, suppressed vascular lumen formation and inhibited invasion cell numbers in a dose-dependent manner. The α-smooth muscle actin, collagen I, E-cadherin, phosphorylated (p-) phosphoinositide 3-kinase (PI3K), p-protein kinase B (AKT), p-mammalian target of rapamycin (m-TOR) and hypoxia inducible factor subunit alpha (HIF-1α) protein expression levels of the curcumin-treated groups were significantly downregulated in a dose-dependent manner compared with the platelet group. HIF-1α protein expression levels in the nucleus of the curcumin-treated groups were significantly suppressed in a dose-dependent manner compared with the platelet group. In conclusion, curcumin suppressed INMEC invasion and angiogenesis induced by activated platelets via inhibiting the activation of the PI3K/AKT/mTOR pathway.

Small molecule inhibitors of epithelial-mesenchymal transition for the treatment of cancer and fibrosis

Tissue fibrosis and cancer both lead to high morbidity and mortality worldwide; thus, effective therapeutic strategies are urgently needed. Because drug resistance has been widely reported in fibrotic tissue and cancer, developing a strategy to discover novel targets for targeted drug intervention is necessary for the effective treatment of fibrosis and cancer. Although many factors lead to fibrosis and cancer, pathophysiological analysis has demonstrated that tissue fibrosis and cancer share a common process of epithelial-mesenchymal transition (EMT). EMT is associated with many mediators, including transcription factors (Snail, zinc-finger E-box-binding protein and signal transducer and activator of transcription 3), signaling pathways (transforming growth factor-β1, RAC-α serine/threonine-protein kinase, Wnt, nuclear factor-kappa B, peroxisome proliferator-activated receptor, Notch, and RAS), RNA-binding proteins (ESRP1 and ESRP2) and microRNAs. Therefore, drugs targeting EMT may be a promising therapy against both fibrosis and tumors. A large number of compounds that are synthesized or derived from natural products and their derivatives suppress the EMT by targeting these mediators in fibrosis and cancer. By targeting EMT, these compounds exhibited anticancer effects in multiple cancer types, and some of them also showed antifibrotic effects. Therefore, drugs targeting EMT not only have both antifibrotic and anticancer effects but also exert effective therapeutic effects on multiorgan fibrosis and cancer, which provides effective therapy against fibrosis and cancer. Taken together, the results highlighted in this review provide new concepts for discovering new antifibrotic and antitumor drugs.

Probucol ameliorates EMT and lung fibrosis through restoration of SIRT3 expression

Pulmonary fibrosis is a progressive fibrotic lung disease with a paucity of therapeutic options. Here we investigated the potential roles of probucol, a cholesterol-lowering drug with potent anti-oxidation properties, on pulmonary epithelial-mesenchymal transition (EMT) and fibrosis. We found that bleomycin-induced lung fibrosis was associated with increased transforming growth factor (TGF)-β1, α-smooth muscle actin (α-SMA) and decreased E-cadherin expression in lung tissues, indicating EMT formation. Bleomycin treatment resulted in an induction of oxidative stress in lung tissues. Probucol treatment attenuated bleomycin-induced TGF-β1 production, EMT and pulmonary fibrosis, meanwhile it suppressed bleomycin-induced oxidative stress. Bleomycin treatment resulted in decreases in protein expressions of Sirtuin 3 (SIRT3) in the lung, which were restored by ROS scavenger NAC and probucol treatment, suggesting that probucol might restore SIRT3 expression by suppressing bleomycin-induced oxidative stress. In the mouse alveolar type II epithelial cell line MLE-12, probucol treatment leads to an increase in SIRT3 expression in bleomycin-treated AT-II cells, which might contribute to the inhibitory effect of probucol on EMT through suppressing hypoxia inducible factor (HIF)-1α/TGF-β1 pathway. In addition, probucol inhibited bleomycin-induced macrophage infiltration in the lung. Bleomycin decreased SIRT3 protein expression, whereas increased HIF-1α activation and TGF-β1 release in the mouse macrophage cell line RAW264.7, which were attenuated by probucol treatment. Taken together, the present study suggests that probucol may ameliorate EMT and lung fibrosis through restoration of SIRT3 expression. The data obtained in this study provides proof for the idea that probucol may be a potential therapeutic option for the treatment of pulmonary fibrosis.

Atorvastatin attenuates paraquat poisoning-induced epithelial-mesenchymal transition via downregulating hypoxia-inducible factor-1 alpha

AIM

This study investigated the effects of atorvastatin (ATS) on the paraquat (PQ)-induced epithelial-mesenchymal transition (EMT) and the potential mechanism through hypoxia-inducible factor-1 alpha (HIF-1α).

MAIN METHODS

Sprague-Dawley (SD) rats were randomly divided into a control group (n = 5), PQ group (n = 20), PQ + ATS L group (n = 20, ATS 20 mg/kg daily) and PQ + ATS H group (n = 20, ATS 40 mg/kg daily). All treated rats were given a 20% PQ solution (50 mg/kg) once by gavage and then sacrificed 12, 24, 72 and 168 h after PQ exposure. The A549 and RLE-6TN cell lines were treated with ATS, PQ or both for 24 h. Mesenchymal (α-SMA and vimentin) and epithelial (E-cadherin and ZO-1) cell marker expression was tested both in vivo and in vitro. The effects of ATS on HIF-1α and β‑catenin expression were also evaluated.

KEY FINDINGS

ATS alleviated PQ poisoning-induced lung injury and pulmonary fibrosis in vivo. This effect was dose-dependent. ATS treatment attenuated the EMT by increasing the levels of the epithelial markers E-cadherin and ZO-1 and by decreasing the expression of the mesenchymal markers α-SMA and vimentin in both lung tissues and in vitro cell culture. In addition, ATS treatment may decrease the HIF-1α and β‑catenin levels both in vivo and in vitro.

SIGNIFICANCE

In conclusion, ATS can attenuate PQ-induced pulmonary fibrosis. The mechanism may involve the downregulation of the HIF-1α/β‑catenin pathway and the inhibition of the PQ-induced EMT by ATS. ATS may be considered as a therapeutic agent for PQ poisoning-induced pulmonary fibrosis.

Modeling of mesenchymal hybrid epithelial state and phenotypic transitions in EMT and MET processes of cancer cells

Based on the transcriptional regulatory mechanisms between microRNA-200 and transcription factor ZEB in an individual cancer cell, a minimal dynamic model is proposed to study the epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) processes of cancer cells. It is shown that each cancer cell can exit in any of three phenotypic states: the epithelial (E) state, the mesenchymal (M) state, and the epithelial/mesenchymal (E/M) hybrid state, and the state of cancer cell can interconvert between different states. The phase diagram shows that there are monostable, bistable, and tristable phenotypic states regions in a parameters plane. It is found that different pathway in the phase diagram can correspond to the EMT or the MET process of cancer cells, and there are two possible EMT processes. It is important that the experimental phenomenon of E/M hybrid state appearing in the EMT process but rather in the MET process can be understood through different pathways in the phase diagram. Our numerical simulations show that the effects of noise are opposite to these of time delay on the expression of transcription factor ZEB, and there is competition between noise and time delay in phenotypic transitions process of cancer cells.

Hypoxia-induced LncRNA-BX111 promotes metastasis and progression of pancreatic cancer through regulating ZEB1 transcription

The contribution of long noncoding RNAs (lncRNAs) to pancreatic cancer progression and the regulatory mechanisms of their expression are attractive areas. In the present study, the overexpression of lncRNA-BX111887 (BX111) in pancreatic cancer tissues was detected by microarray and further validated in a cohort of pancreatic cancer tissues. We further demonstrated that knockdown or overexpression of BX111 dramatically repressed or enhanced proliferation and invasion of pancreatic cancer cells. Mechanically, BX111 activated transcription of ZEB1, a key regulator for epithelia-mesenchymal transition (EMT), via recruiting transcriptional factor Y-box protein (YB1) to its promoter region. Moreover, we revealed that BX111 transcription was induced by hypoxia-inducible factor (HIF-1α) in response to hypoxia. In addition, BX111 contributed to the hypoxia-induced EMT of pancreatic cells by regulating expression of ZEB1 and its downstream proteins E-cadherin and MMP2. Coincidence with in vitro results, BX111 depletion effectively inhibited growth and metastasis of xenograft tumor in vivo. The clinical samples of pancreatic cancer further confirmed a positive association between BX111 and ZEB1. Moreover, high BX111 expression was correlated with late TNM stage, lymphatic invasion and distant metastasis, as well as short overall survival time in patients. Taken together, our findings implicate a hypoxia-induced lncRNA contributes to metastasis and progression of pancreatic cancer, and suggest BX111 might be applied as a potential biomarker and therapeutic target for pancreatic cancer.

The role of HIF-1α in the TGF-β2-mediated epithelial-to-mesenchymal transition of human lens epithelial cells

Human lens epithelial cells (HLE) undergo mesenchymal transition and become fibrotic during posterior capsule opacification (PCO), which is a frequent complication after cataract surgery. TGF-β2 has been implicated in this fibrosis. Previous studies have focused on the role of hypoxia-inducible factor-1α (HIF-1α) in fibrotic diseases, but the role of HIF-1α in the TGF-β2-mediated fibrosis in HLE is not known. TGF-β2 treatment (10 ng/mL, 48 h) increased the HIF-1α levels along with the EMT markers in cultured human lens epithelial cells (FHL124 cells). The increase in HIF-1α corresponded to an increase in VEGF-A in the culture medium. However, exogenous addition of VEGF-A (up to 10 ng/mL) did not alter the EMT marker levels in HLE. Addition of a prolyl hydroxylase inhibitor, dimethyloxalylglycine (DMOG, up to 10 µM), enhanced the levels of HIF-1α, and secreted VEGF-A but did not alter the EMT marker levels. However, treatment of cells with a HIF-1α translational inhibitor, KC7F2, significantly reduced the TGF-β2-mediated EMT response. This was accompanied by a reduction in the ERK phosphorylation and nuclear translocation of Snail and Slug. Together, these data suggest that HIF-1α is important for the TGF-β2-mediated EMT of human lens epithelial cells.

Respiratory hazard of Li-ion battery components: elective toxicity of lithium cobalt oxide (LiCoO2) particles in a mouse bioassay

Rechargeable Li-ion batteries (LIB) are increasingly produced and used worldwide. LIB electrodes are made of micrometric and low solubility particles, consisting of toxicologically relevant elements. The health hazard of these materials is not known. Here, we investigated the respiratory hazard of three leading LIB components (LiFePO₄ or LFP, Li₄Ti₅O₁₂ or LTO, and LiCoO₂ or LCO) and their mechanisms of action. Particles were characterized physico-chemically and elemental bioaccessibility was documented. Lung inflammation and fibrotic responses, as well as particle persistence and ion bioavailability, were assessed in mice after aspiration of LIB particles (0.5 or 2 mg); crystalline silica (2 mg) was used as reference. Acute inflammatory lung responses were recorded with the 3 LIB particles and silica, LCO being the most potent. Inflammation persisted 2 m after LFP, LCO and silica, in association with fibrosis in LCO and silica lungs. LIB particles persisted in the lungs after 2 m. Endogenous iron co-localized with cobalt in LCO lungs, indicating the formation of ferruginous bodies. Fe and Co ions were detected in the broncho-alveolar lavage fluids of LFP and LCO lungs, respectively. Hypoxia-inducible factor (HIF) -1α, a marker of fibrosis and of the biological activity of Co ions, was upregulated in LCO and silica lungs. This study identified, for the first time, the respiratory hazard of LIB particles. LCO was at least as potent as crystalline silica to induce lung inflammation and fibrosis. Iron and cobalt, but not lithium, ions appear to contribute to LFP and LCO toxicity, respectively.

Deficiency of protein-L-isoaspartate (D-aspartate) O-methyl-transferase expression under endoplasmic reticulum stress promotes epithelial mesenchymal transition in lung adenocarcinoma

A prognostic association between the novel chaperone protein-L-isoaspartate (D-aspartate) O-methyltransferase (PIMT) and lung adenocarcinoma has recently been reported. Here, we evaluated the functional roles of PIMT in the progression of lung adenocarcinoma. PIMT expression was detectable in 6 lung adenocarcinoma cell lines: A549, H441, H460, H1650, Calu 1, and Calu 6 cell lines. In A549 and H441 cells, knockdown by PIMT using silencing RNA of PIMT (si-PIMT) and/or small hairpin-RNA (sh-PIMT) induced a decrease in the expression of E-cadherin with an increase in vimentin expression, indicating that the epithelial to mesenchymal transition (EMT) was induced. Cell mobility, including migration and invasion capability, was increased in sh-PIMT A549 stable and si-PIMT H441 cells compared to in control cells. Endoplasmic reticulum (ER) stress, such as Thapsigargin (Tg) stress and hypoxia, induced EMT in A549 cells but not in other cell types, with an increase in GRP78 expression, whereas overexpression of PIMT reduced the EMT and cell invasion under stress conditions. The expression of hypoxia inducible factor-1 alpha (HIF1α) and Twist increased in sh-PIMT A549 and si-PIMT H441 cells, and Tg stress increased HIF1α expression levels in A549 cells in a dose-dependent manner. Moreover, LW6, an HIF1α inhibitor, reduced EMT, cancer invasion, and the levels of Twist in sh-PIMT A549 cells. Our results indicate that deficiency of supplemental PIMT expression under ER stress facilitates EMT and cell invasion in some cell types of lung adenocarcinoma.

Rapamycin protects against paraquat-induced pulmonary epithelial-mesenchymal transition via the Wnt/β-catenin signaling pathway

Paraquat (PQ) is a herbicide that is widely used in developing countries, and pulmonary fibrosisis one of the most typical features of PQ poisoning. The molecular mechanism underlying PQ toxicity is largely unknown, which makes it difficult to treat. In the present study, western blot analysis, reverse transcription-quantitative polymerase chain reaction and fluorescent immunostaining were used to analyze the effects of rapamycin on PQ-induced epithelial-mesenchymal transition (EMT) in A549 and MRC-5 cells. It was revealed that rapamycin significantly downregulated the mesenchymal cell marker, α-smooth muscle actin, and significantly upregulated the epithelial cell marker, E-cadherin, at mRNA and protein expression levels compared with the PQ group. Treatment with PQ significantly increased Wnt1, low-density lipoprotein receptor-related protein (LRP)5, LRP6 and β-catenin expression levels in A549 cells, while rapamycin significantly inhibited these effects of PQ. Activation of the Wnt signaling pathway using lithium chloride attenuated the inhibitory effects of rapamycin on PQ-induced EMT. In conclusion, rapamycin protects against PQ-induced pulmonary EMT via the Wnt/β-catenin signaling pathway.

Hypoxia-inducible factor-1α regulates epithelial-to-mesenchymal transition in paraquat-induced pulmonary fibrosis by activating lysyl oxidase

Pulmonary fibrosis (PF) is one of the most prevalent causes of death following paraquat (PQ) poisoning. As demonstrated in previous studies by the present authors, epithelial-to-mesenchymal transition (EMT) is associated with PQ-induced PF. In addition, hypoxia-inducible factor-1α (HIF-1α) and lysyl oxidase (LOX) promote EMT following PQ poisoning. However, the association between HIF-1α- and LOX-mediated regulation of EMT remains unclear. The present study investigated the association between HIF-1α and LOX with regard to PQ-induced EMT. A549 and RLE-6TN cells were treated with PQ, and HIF-1α and LOX expression was silenced with short interfering RNAs. Changes in the expression of HIF-1α, LOX, β-catenin and EMT-related makers were detected using real-time quantitative polymerase chain reaction, immunofluorescence, and western blotting. HIF-1α and LOX were associated with PQ-induced EMT, and their expression levels were significantly increased (P<0.05). LOX expression was significantly decreased following PQ poisoning when HIF-1α expression was inhibited (P<0.05). However, the level of HIF-1α did not change significantly when LOX was silenced. The expression level of β-catenin and the degree of EMT were significantly decreased following HIF-1α and LOX silencing in both cell lines (P<0.05). The association between HIF-1α and LOX in regulating EMT during PQ-induced PF may be unidirectional. HIF-1α may regulate PQ-induced EMT through the LOX/β-catenin pathway.

Potential contribution of alveolar epithelial type I cells to pulmonary fibrosis

Pulmonary fibrosis (PF) is characterized by inflammation and fibrosis of the interstitium and destruction of alveolar histoarchitecture ultimately leading to a fatal impairment of lung function. Different concepts describe either a dominant role of inflammatory pathways or a disturbed remodeling of resident cells of the lung parenchyma during fibrogenesis. Further, a combination of both the mechanisms has been postulated. The present review emphasizes the particular involvement of alveolar epithelial type I cells in all these processes, their contribution to innate immune/inflammatory functions and maintenance of proper alveolar barrier functions. Amongst the different inflammatory and repair events the purinergic receptor P2X7, an ATP-gated cationic channel that regulates not only apoptosis, necrosis, autophagy, and NLPR3 inflammosome activation, but also the turnover of diverse tight junction (TJ) and water channel proteins, seems to be essential for the stability of alveolar barrier integrity and for the interaction with protective factors during lung injury.

Aberrant Wnt/Beta-Catenin Pathway Activation in Dialysate-Induced Peritoneal Fibrosis

Peritoneal dialysis (PD)-associated peritoneal fibrosis is a chronic progress which induces ultrafiltration failure. It remains a challenge to prevent the progression of PD-associated fibrosis in clinic practice. Wnt/β-catenin pathway plays important role in many severe fibrotic diseases, here we investigated its contribution to the development of peritoneal damage. We isolated mesothelial cells (MC) from the effluent of PD patients and found that the expressions of Wnt1, Wnt5a, β-catenin, and LEF1 were increased in patients with more than 1-year PD compared with patients who just started with PD (<1 month). The elevated expressions of Wnts and β-catenin were accompanied with changes in the expressions of E-cadherin, α-SMA, COL-I, and FN mRNA and proteins, which are known related to mesothelial-mesenchymal transition (MMT). In addition, treatment with high glucose significantly increased the expression of Wnt1, Wnt5a, β-catenin, and LEF1 as well as the expression of α-SMA, COL-I, and FN in human peritoneal mesothelial cells (HPMC), whereas the expression of E-cadherin was reduced. Dickkopf-1 (DKK-1) is an endogenous inhibitor of Wnt/β-catenin signaling. Overexpression of DKK1 transgene significantly decreased the expression of β-catenin and attenuated the process of MMT as indicated by the decreased expression of α-SMA, COL-I, and FN and the increased expression of E-cadherin. Furthermore, TGF-β1 treatment significantly activated the Wnt/β-catenin pathway in HPMCs, while DKK1 blocked the TGF-β1-induced Wnt signaling activation and significantly inhibited the process of MMT. These data suggest that the canonical Wnt/β-catenin pathway plays an important role in the MMT and fibrosis induced by PD.

Porous Se@SiO2 nanospheres treated paraquat-induced acute lung injury by resisting oxidative stress

Acute paraquat (PQ) poisoning is one of the most common forms of pesticide poisoning. Oxidative stress and inflammation are thought to be important mechanisms in PQ-induced acute lung injury (ALI). Selenium (Se) can scavenge intracellular free radicals directly or indirectly. In this study, we investigated whether porous Se@SiO₂ nanospheres could alleviate oxidative stress and inflammation in PQ-induced ALI. Male Sprague Dawley rats and RLE-6TN cells were used in this study. Rats were categorized into 3 groups: control (n=6), PQ (n=18), and PQ + Se@SiO₂ (n=18). The PQ and PQ + Se@SiO₂ groups were randomly and evenly divided into 3 sub-groups according to different time points (24, 48 and 72 h) after PQ treatment. Porous Se@SiO₂ nanospheres 1 mg/kg (in the PQ + Se@SiO₂ group) were administered via intraperitoneal injection every 24 h. Expression levels of reduced glutathione, malondialdehyde, superoxide dismutase, reactive oxygen species (ROS), nuclear factor-κB (NF-κB), phosphorylated NF-κB (p-NF-κB), tumor necrosis factor-α and interleukin-1β were detected, and a histological analysis of rat lung tissues was performed. The results showed that the levels of ROS, malondialdehyde, NF-κB, p-NF-κB, tumor necrosis factor-α and interleukin-1β were markedly increased after PQ treatment. Glutathione and superoxide dismutase levels were reduced. However, treatment with porous Se@SiO₂ nanospheres markedly alleviated PQ-induced oxidative stress and inflammation. Additionally, the results from histological examinations and wet-to-dry weight ratios of rat lung tissues showed that lung damage was reduced after porous Se@SiO₂ nanosphere treatment. These data indicate that porous Se@SiO₂ nanospheres may reduce NF-κB, p-NF-κB and inflammatory cytokine levels by inhibiting ROS in PQ-induced ALI. This study demonstrates that porous Se@SiO₂ nanospheres may be a therapeutic method for use in the future for PQ poisoning.

A positive feedback loop promotes HIF-1α stability through miR-210-mediated suppression of RUNX3 in paraquat-induced EMT

Irreversible pulmonary fibrosis induced by paraquat (PQ) poisoning is the major cause of death in patients with PQ poisoning. The epithelial–mesenchymal transition (EMT) is postulated to be one of the main mechanisms of pulmonary fibrosis. Here, we investigated the role of miR‐210 in PQ‐induced EMT and its relationship with hypoxia‐inducible factor‐1α (HIF‐1α). Western blotting, immunofluorescence, immunoprecipitation and other methods were used in this study. We found that miR‐210 expression was significantly increased after PQ poisoning, and it may be regulated by HIF‐1α. Overexpression of miR‐210 further increased the HIF‐1α protein level and promoted EMT. Moreover, miR‐210 knock‐down reduced the HIF‐1α protein level and decreased the degree of EMT. Runt‐related transcription factor‐3 (RUNX3), a direct target of miR‐210, was inhibited by miR‐210 in response to PQ poisoning. RUNX3 increased the hydroxylation ability of prolyl hydroxylase domain‐containing protein 2 (PHD2), a key enzyme that promotes HIF‐1α degradation. PHD2 immunoprecipitated with RUNX3 and its level changed similarly to that of RUNX3. The expression of the HIF‐1α protein was significantly reduced when RUNX3 was overexpressed. HIF‐1α protein levels were markedly increased when RUNX3 was silenced. Based on these results, a positive feedback loop may exist between miR‐210 and HIF‐1α. The mechanism may function through miR‐210‐mediated repression of RUNX3, which further decreases the hydroxylation activity of PHD2, enhances the stability of HIF‐1α, and promotes PQ‐induced EMT, aggravating the progression of pulmonary fibrosis. This study further elucidates the mechanism of PQ‐induced pulmonary fibrosis and may provide a new perspective for the future development of therapies.

Expression and significance of GRHL2 in esophageal cancer

Esophageal cancer (EC) is one of the most common causes of cancer-related mortality in the world. Although much effort has been made to improve the 5-year survival rate of patients with EC, it still remains low due to diagnosis at an advanced stage, aggressive local invasion, early metastasis, and resistance to chemotherapy. Although grainyhead-like 2 (GRHL2) has attracted interest since it has been recently identified as a novel suppressor of the epithelial–mesenchymal transition, clinical values of GRHL2 and its relationship with the metastasis-related factors, such as hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor (VEGF), remain unclear. In order to investigate the expression of GRHL2, HIF-1α, and VEGF, and their correlation with angiogenesis in EC, 63 patients with EC were examined. The expression of GRHL2, HIF-1α, and VEGF in tumor tissues was higher than that in adjacent tissues and was associated with tumor differentiation. GRHL2 expression was significantly correlated with lymph node metastasis and invasion depth, whereas VEGF expression was associated with tumor (TNM) stage. A significant correlation was found between the expression of GRHL2 and HIF-1α. The patients expressing low GRHL2 and high HIF-1α showed significant reduction in both overall survival rate and disease-free survival rate. The results demonstrated that abnormal expression of GRHL2 is common in EC, and low expression of GRHL2 accompanied by a high expression of HIF-1α indicates poor prognosis.

LncRNA-ATB/microRNA-200a/β-catenin regulatory axis involved in the progression of HCV-related hepatic fibrosis

OBJECTIVE(S)

Long noncoding RNAs (lncRNAs)-activated by transforming growth factor beta (lncRNA-ATB) is known to be involved in the invasion of hepatocellular carcinoma by regulating target genes of miR-200a. However, the role and molecular mechanisms of lncRNA-ATB/miR-200a in HCV-related liver fibrosis remains unclear. In this study, we examined the expression of lncRNA-ATB/miR-200a, and their target gene β-Catenin in liver tissues of HCV patients and hepatic stellate cells (HSCs) to elucidate the possible role of lncRNA-ATB/miR-200a axis in HSC activation and development of liver fibrosis.

MATERIALS AND METHODS

Liver tissues were obtained by biopsy or surgery from eighteen HCV patients with severe liver fibrosis and six healthy subjects (control). Conditioned media (CM) from cultured HepG2-CORE cells (HepG2 cells stably expressing HCV core protein) were used to treat LX-2 cells. The binding sites between lncRNA-ATB/miR-200a and β-catenin were predicted and then verified by a dual luciferase reporter assay. The effect of lncRNA-ATB/miR-200a/β-catenin on HSC activation was assessed by examining the expression of alpha-smooth muscle actin (α-SMA) and collagen type 1 alpha 1 (Col1A1) in HSCs. Further, the regulatory role of lncRNA-ATB on HSC activation and miR-200a/β-catenin expression was assessed by using siRNA-mediated knockdown of lncRNA-ATB.

RESULTS

LncRNA-ATB was up-regulated in fibrotic liver tissues and activated LX-2 cells treated with CM from HepG2-CORE cells. Dual luciferase reporter assays confirmed that lncRNA-ATB contained common binding sites for miR-200a and β-catenin. Decreased expression of miR-200a and increased expression of β-catenin were observed in liver tissues of patients with HCV-related hepatic fibrosis and activated HSCs. Knockdown of lncRNA-ATB could down-regulate β-catenin expression by up-regulating the endogenous miR-200a and suppress the activation of LX-2 cells.

CONCLUSION

LncRNA-ATB/miR-200a/β-catenin regulatory axis likely contributed to the development of liver fibrosis in HCV patients. Knockdown of lncRNA-ATB might be a novel therapeutic target for HCV-related liver fibrosis.

Beta-catenin participates in dialysate-induced peritoneal fibrosis via enhanced peritoneal cell epithelial-to-mesenchymal transition

Long‐term exposure to peritoneal dialysate with high glucose (HG) leads to peritoneal fibrosis and thus decreases dialysis efficiency. In this study, we explored the role of β‐catenin in this process. C57BL/6 mice received daily intraperitoneal injection with 10% of the body weight of saline (control), 4.25% glucose peritoneal dialysis fluid (PDF), or PDF combined with 5 mg·kg⁻¹ of the β‐catenin inhibitor ICG‐001 (PDF+ICG) for 30 days. Also, mice peritoneal epithelial cells (mPECs) were cultured in 4.25% glucose (HG) or combined with 10 μm ICG‐001 (HG+ICG) for 48 h. We found greater thickness of the parietal peritoneum in the PDF‐treated mice. Additionally, lower expression of E‐cadherin, higher expression of Vimentin, β‐catenin, and Snail, and activation of β‐catenin was observed in the mice and in HG‐treated mPECs, all of which were reversed by ICG‐001. The changes in E‐cadherin and Vimentin indicated occurrence of the epithelial‐to‐mesenchymal transition (EMT). Thus, β‐catenin signaling participates in the process of HG‐induced peritoneal fibrosis, and the EMT of peritoneal epithelial cells is one of the underlying mechanisms of this pathological change.

Atorvastatin protected from paraquat-induced cytotoxicity in alveolar macrophages via down-regulation of TLR-4

The current study designed to clarify the mechanism of paraquat-induced cytotoxicity and protective effects of Atorvastatin on freshly isolated alveolar macrophages (AMs). AMs were collected via bronchoalveolar lavage and exposed to various concentrations of paraquat in the presence and absence of atorvastatin for 24h. Cell viability, myeloperoxidase activity; nitric oxide generation and total antioxidant capacity were assessed. Expression of TLR-4 at mRNA and protein levels were studied by using PCR and western blot methods Atorvastatin enhanced the paraquat-reduced cell viability and reduced the paraquat-induced myeloperoxidase activity and nitric oxide production. Moreover, atorvastatin down-regulated by 60% the paraquat up-regulated expression of TLR-4 at protein and mRNA level. Our results suggest that, AMs in vitro model could be a novel cytological tool for studies on paraquat poisoning and therapy regimens. Additionally, atorvastatin cytoprotective effects on paraquat-induced cytotoxicity partly attribute to its anti-myeloperoxidase, antioxidant properties, which might be regulated via TLR-4 expression.

Regulatory mechanisms of TGF-β1-induced fibrogenesis of human alveolar epithelial cells

Pulmonary fibrosis is characterized by an extensive activation of fibrogenic cells and deposition of extracellular matrix (ECM). Transforming growth factor (TGF)‐β1 plays a pivotal role in the pathogenesis of pulmonary fibrosis, probably through the epithelial‐ to‐mesenchymal transition (EMT) and ECM production. The present study investigates potential mechanism by which TGF‐β1 induces EMT and ECM production in the fibrogenesis of human lung epithelial cells during pulmonary fibrosis. The expression of EMT phenotype and other proteins relevant to fibrogenesis were measured and the cell bio‐behaviours were assessed using Cell‐IQ Alive Image Monitoring System. We found that TGF‐β1‐induced EMT was accompanied with increased collagen I deposition, which may be involved in the regulation of connective tissue growth factor (CTGF) and phosphoinositide 3‐kinase (PI3K) signalling pathway. Treatment with PI3K inhibitors significantly attenuated the TGF‐β1‐ induced EMT, CTGF expression and collagen I synthesis in lung epithelial cells. The interference of CTGF expression impaired the basal and TGF‐β1‐stimulated collagen I deposition, but did not affect the process of EMT. Our data indicate that the signal pathway of TGF‐β1/PI3K/CTGF plays an important role in the fibrogenesis of human lung epithelial cells, which may be a novel therapeutic approach to prevent and treat pulmonary fibrosis.