miR-541 is associated with the prognosis of liver cirrhosis and directly targets JAG2 to inhibit the activation of hepatic stellate cells

BACKGROUND

The activation of hepatic stellate cells (HSCs) has been emphasized as a leading event of the pathogenesis of liver cirrhosis, while the exact mechanism of its activation is largely unknown. Furthermore, the novel non-invasive predictors of prognosis in cirrhotic patients warrant more exploration. miR-541 has been identified as a tumor suppressor in hepatocellular carcinoma and a regulator of fibrotic disease, such as lung fibrosis and renal fibrosis. However, its role in liver cirrhosis has not been reported.

METHODS

Real-time PCR was used to detect miR-541 expression in the liver tissues and sera of liver cirrhosis patients and in the human LX-2. Gain- and loss-of-function assays were performed to evaluate the effects of miR-541 on the activation of LX-2. Bioinformatics analysis and a luciferase reporter assay were conducted to investigate the target gene of miR-541.

RESULTS

miR-541 was downregulated in the tissues and sera of patients with liver cirrhosis, which was exacerbated by deteriorating disease severity. Importantly, the lower expression of miR-541 was associated with more episodes of complications including ascites and hepatic encephalopathy, a shorter overall lifespan, and decompensation-free survival. Moreover, multivariate Cox's regression analysis verified lower serum miR-541 as an independent risk factor for liver-related death in cirrhotic patients (HR = 0.394; 95% CI: 0.164-0.947; P = 0.037). miR-541 was also decreased in LX-2 cells activated by TGF-β and the overexpression of miR-541 inhibited the proliferation, activation and hydroxyproline secretion of LX-2 cells. JAG2 is an important ligand of Notch signaling and was identified as a direct target gene of miR-541. The expression of JAG2 was upregulated in the liver tissues of cirrhotic patients and was inversely correlated with miR-541 levels. A rescue assay further confirmed that JAG2 was involved in the function of miR-541 when regulating LX-2 activation and Notch signaling.

CONCLUSIONS

Dysregulation of miR-541/JAG2 axis might be a as a new mechanism of liver fibrosis, and miR-541 could serve as a novel non-invasive biomarker and therapeutic targets for liver cirrhosis.

Downregulation of miR-541 induced by heat stress contributes to malignant transformation of human bronchial epithelial cells via HSP27

Environmental factors are one of the important factors affecting the occurrence of lung cancer. However, few studies have been done on the relationship between hot environment and lung cancer. In the present study, we demonstrated that heat stress leads to anchorage-independent proliferation, mitochondrial apoptosis, and autophagy of Beas-2B cells, which are normal lung bronchial epithelial cells. Heat shock protein 27 (HSP27) promoted heat stress-induced anchorage-independent proliferation and autophagy, but suppressed mitochondrial apoptosis, indicating that HSP27 might act as an oncogene in the malignant transformation of lung epithelial cells. We also showed that HSP27 promoted autophagy of these cells under heat stress via autophagy related 7 (ATG7) and ETS Transcription Factor ELK1 (ELK1), a transcription factor of ATG7, under heat stress. In addition, we showed that HSP27 translation could be repressed by microRNA miR-541, and the biological effects of miR-541 were the opposite to HSP27, suggesting that HSP27 is a downstream target of miR-541. In this study, we characterized a new mechanism whereby HSP27 promotes cell transformation during the onset of lung cancer. Our studies provide new insights into the molecular mechanisms underlying the lung carcinogenic effect of heat exposure. Specifically, heat stress promotes translation of HSP27 by inhibiting miR-541 accumulation, ultimately resulting in activation of autophagy, inhibition of mitochondrial apoptotic pathway and malignant transformation of Human Bronchial Epithelial Cells. This study identifies miR-541 as a potential prognostic biomarker or therapeutic target to improve theory of environmental carcinogenesis.

EPA attenuates epithelial-mesenchymal transition and fibrosis through the TGF-β1/Smad3/ILK pathway in renal tubular epithelial HK-2 cells by up-regulating miR-541

BACKGROUND

It was reported that eicosapentaenoic acid (EPA) could prevent tubulointerstitial injury in kidney. EPA could also inhibit the epithelial-mesenchymal transition (EMT) of HK-2 cells stimulated by albumin (Alb) in vitro. However, the regulating molecular mechanism of EPA remains to be elucidated.

METHODS

An immortalized human proximal tubular cell line (human kidney-2 (HK-2) cells) was used in all experiments. MTT assay was employed to determine the effect of Alb or EPA on the cell viability of HK-2 cells. The miR-541 expression, the mRNA levels of EMT markers E-cadherin, α-smooth muscle actin (α-SMA), and fibrogenesis markers Collagen I and fibronectin (FN) were examined by RT-qPCR assay. The protein levels of E-cadherin, α-SMA and Collagen I, transforming growth factor β1 (TGF-β1)/Smad3/integrin-linked kinase (ILK) pathway-related protein TGF-β1, pSmad2/3, Smad7 and ILK were measured by western blot. Enzyme-linked immunosorbent assay (ELISA) was performed to detect FN expression. The target relationship between miR-541 and TGF-β1 was confirmed by bioinformatics, luciferase reporter assay and western blot.

RESULTS

Low doses of Alb had no effect on the cell viability of HK-2 cells, while EPA repressed the cell viability of HK-2 cells in a concentration-dependent manner. EPA could inhibit EMT and fibrosis and increase the miR-541 expression of HK-2 cells exposed to Alb. Interestingly, introduction of miR-541 effectively abolished the EMT and fibrosis of HK-2 cells stimulated by Alb. Bioinformatics analysis predicted TGF-β1 as a target gene of miR-541, and subsequent luciferase reporter assay and western blot further supported the prediction. miR-541 counter-regulated TGF-β1 expression, and inhibited the TGF-β1/Smad3/ILK pathway. Alb treatment activated the TGF-β1/Smad3/ILK pathway, while EPA inhibited the activation of the pathway. miR-541 inhibitors reversed the effects of EPA on EMT, fibrosis, and TGF-β1/Smad3/ILK pathway-related protein expression induced by Alb.

CONCLUSION

EPA attenuates EMT and renal fibrosis through the TGF-β1/Smad3/ILK pathway in renal epithelial cells by targeting miR-541.

miR-541 suppresses proliferation and invasion of squamous cell lung carcinoma cell lines via directly targeting high-mobility group AT-hook 2

An increasing number of studies have demonstrated that micro-ribonucleic acids (miRNAs) are important tumor suppressors during carcinogenesis. However, the function of miRNA-541 (miR-541) in malignancies, especially lung cancer, has not been widely reported. In this study, miR-541 expression was significantly decreased in squamous cell lung carcinoma (SCLC) cancerous tissue and SCLC cell lines. To analyze miR-541 function in SCLC, we overexpressed miR-541 in SCLC cell lines (SK-MES-1 and H226). According to the CCK8, wound scratch, and transwell invasion assay results, miR-541 overexpression significantly inhibited SCLC cell proliferation, migration, and invasion ability. Next, using RT-PCR, Western blotting, immunocytochemistry, and luciferase assays, HMGA2 was identified, for the first time, as a direct regulatory target of miR-541 in SK-MES-1 and H226 cells. Furthermore, upregulating HMGA2 expression significantly alleviated the suppressive effects of miR-541 on SK-MES-1 and H226 cell proliferation, migration, and invasion. In summary, our study revealed that miR-541 inhibited SCLC proliferation and invasion by directly targeting HMGA2.

miR-541 Contributes to Microcystin-LR-Induced Reproductive Toxicity through Regulating the Expression of p15 in Mice

Microcystin-leucine arginine (MC-LR) is a harmful cyanotoxin produced by cyanobacteria. MC-LR can exert endocrine-disrupting activities in many organisms. We have previously demonstrated that MC-LR exerts both acute and chronic reproductive toxicity in male mice, resulting in a decline in sperm quality and damage to testicular structure. Moreover, we also observed extensive alterations in a panel of microRNAs in spermatogonial cells after exposure to MC-LR. In this study, we have confirmed that miR-541 was significantly increased both in GC-1 cells (in vitro) and in mouse testes (in vivo) after exposure to MC-LR. Our data support that p15 was the target gene of miR-541. Increase in miR-541 led to a reduction of p15 and murine double minute2 (MDM2), promoting the activation of p53 signaling and MC-LR-mediated cell apoptosis. Moreover, cells responded to MC-LR with reduced viability and increased apoptosis. Consistently, inhibiting miR-541 could upregulate the expression of p15 and MDM2, resulting in the downregulation of phospho-p53. Downregulation of miR-541 promoted cell viability by reducing MC-LR-induced cell apoptosis. In conclusion, we demonstrate here a crucial role for miR-541 in MC-LR-induced toxic effects on the reproductive system, in an attempt to provide a rational strategy for the diagnosis and treatment of MC-LR-induced impairment in the reproductive system.

MicroRNA-541 promotes the proliferation of vascular smooth muscle cells by targeting IRF7

MiRNAs play crucial roles in abnormal proliferation and invasion of VSMCs. However, the roles and mechanisms of miRNAs in VSMCs are not fully understood. In our study, we demonstrated that PDGF-BB and serum induced proliferation of VSMCs led to the upregulation of miR-541. We also showed that overexpression of miR-541 promoted VSMC proliferation and invasion. In addition, Interferon regulatory factor 7 (IRF7) was found to be a potential target of miR-541 and upregulation of IRF7 could inhibit VSMC proliferation. Restored expression of miR-541 promoted IRF7-inhibited VSMCs proliferation. In conclusion, these findings suggest that inhibitors targeting miR-541 or its specific downstream molecules may be therapeutic strategy for VSMC growth-related diseases.