Epigenetic silenced miR‐125a‐5p could be self‐activated through targeting Suv39H1 in gastric cancer

Emerging evidence suggests that microRNAs (miRNAs) serve an important role in tumorigenesis and development. Although the low expression of miR‐125a‐5p in gastric cancer has been reported, the underlying mechanism remains unknown. In the current study, the low expression of miR‐125a‐5p in gastric cancer was verified in paired cancer tissues and adjacent non‐tumour tissues. Furthermore, the GC islands in the miR‐125a‐5p region were hypermethylated in the tumour tissues. And the hypermethylation was negatively correlated with the miR‐125a‐5p expression. Target gene screening showed that the histone methyltransferase Suv39H1 was one of the potential target genes. In vitro studies showed that miR‐125a‐5p could directly suppress the Suv39H1 expression and decrease the H3K9me3 levels. On the other hand, the Suv39H1 could induce demethylation of miR‐125a‐5p, resulting in re‐activation of miR‐125a‐5p. What is more, overexpessing miR‐125a‐5p could also self‐activate the silenced miR‐125a‐5p in gastric cancer cells, which suppressed cell migration, invasion and proliferation in vitro and inhibited cancer progression in vivo. Thus, we uncovered here that the epigenetic silenced miR‐125a‐5p could be self‐activated through targeting Suv39H1 in gastric cancer, suggesting that miR‐125a‐5p might be not only the potential prognostic value as a tumour biomarker but also potential therapeutic targets in gastric cancer.     

miR‐96 regulates migration and invasion of bladder cancer through epithelial‐mesenchymal transition in response to transforming growth factor‐β1

Bladder cancer (BC) is one of the most frequent urological malignancies, and its molecular mechanism still remains unclear. Recent studies have revealed that MicroRNA (miRNAs) acted as oncogenes or tumor suppressors in a variety of cancers. MiRNA‐96 has been reported to play a significant role in the development and progression of many cancers. In the current study, we found that transforming growth factor (TGF)‐β1 played a significant role in the progression that miR‐96 conducted. And TGF‐β1 could also regulate the expression of FOXQ1, which is the target gene of miR‐96. Furthermore, miR‐96 induced epithelial‐mesenchymal transition in BC cells, which is driven by TGF‐β1. In conclusion, our data revealed that miR‐96 regulates the progression and epithelial‐mesenchymal transition, which is driven by TGF‐β1 in BC cells; it may provide a new thought for the therapy of BC.     

Circular RNA circABCC4 as the ceRNA of miR‐1182 facilitates prostate cancer progression by promoting FOXP4 expression

In recent years, circular RNAs (circRNAs) have been identified to be essential regulators of various human cancers. However, knowledge of the functions of circRNAs in prostate cancer remains very limited. The correlation between circABCC4 and human cancer is largely unknown. This study aims to investigate the biological functions of circABCC4 in prostate cancer progression and illustrate the underlying mechanism. We found that circABCC4 was remarkably up‐regulated in prostate cancer tissues and cell lines and promoted FOXP4 expression by sponging miR‐1182 in prostate cancer cells. CircABCC4 knockdown markedly suppressed prostate cancer cell proliferation, cell‐cycle progression, migration and invasion in vitro. Furthermore, silencing of the circRNA also delayed tumor growth in vivo. Taken together, our findings indicated that circABCC4 facilitates the malignant behaviour of prostate cancer by promoting FOXP4 expression through sponging of miR‐1182. The circABCC4–miR‐1182‐FOXP4 regulatory loop may be a promising therapeutic target for prostate cancer intervention.     

MicroRNA‐144‐3p suppressed TGF‐β1‐induced lung cancer cell invasion and adhesion by regulating the Src–Akt–Erk pathway

Lung cancer remains a leading cause to cancer‐related death worldwide. The anti‐cancer ability of microRNA‐144‐3p has been reported in many cancer types. This study focused on the mechanisms underlying miR‐144‐3p in inhibiting lung cancer. The expression levels of miR‐144‐3p and steroid receptor coactivator (Src) in different lung cancer cell lines and those in bronchial epithelial cells (16HBE) were compared. miR‐144‐3p mimic and siSrc were transfected into A549 cells. Under the conditions of transforming growth factor‐β1 (TGF‐β1). Small interfering transfection or TGF‐β1 treatment, cell invasive and adhesive abilities were analyzed by Transwell and cell adhesion assays. miR‐144‐3p inhibitor and siSrc were co‐transfected into A549 cells and the changes in cell invasion and adhesion were detected. The activation of Src–protein kinase B–extracellular‐regulated protein kinases (Src–Akt–Erk) pathway was determined using Western blot. The downregulated miR‐144‐3p and upregulated Src were generally detected in lung cancer cell lines and were the most significant genes in A549 cells. Both miR‐144‐3p overexpression and Src inhibition could obviously inhibit the invasion and adhesion abilities of A549 cells in the presence or absence of the effects of TGF‐β1. The inhibition of Src could block the promotive effects of miR‐144‐3p inhibitor and TGF‐β1 on cell invasion and adhesion. Furthermore, we found that miR‐144‐3p could negatively regulate the phosphorylation levels of Akt and Erk. Our data indicated the essential role of Src in the mechanisms underlying TGF‐β1‐induced cell invasion and adhesion of lung cancer, and that miR‐144‐3p could effectively suppress TGF‐β1‐induced aggressive lung cancer cells by regulating Src expression.     

miR‐150 functions as a tumour suppressor in human colorectal cancer by targeting c‐Myb

Our previously published study documented a deregulation of the microRNA miR‐150 in colorectal cancer. Here, we investigated further, in vitro and in vivo, the potential molecular mechanisms underlying the involvement of miR‐150 in colorectal cancer, using the appropriate molecular biological methods. We report that miR‐150 is a key regulator in the tumourigenesis and progression of colorectal cancer, by acting as a tumour suppressor targeting c‐Myb. The current findings suggest that miR‐150 may have important roles in the pathogenesis of colorectal cancer.     

Curcumin reinforces MSC‐derived exosomes in attenuating osteoarthritis via modulating the miR‐124/NF‐kB and miR‐143/ROCK1/TLR9 signalling pathways

Curcumin treatment was reported to delay the progression of OA, but its underlying mechanism remains unclear. In this study, we aimed to investigate the molecular mechanism underlying the role of curcumin in OA treatment. Accordingly, by conducting MTT and flow cytometry assays, we found that the exosomes derived from curcumin‐treated MSCs helped to maintain the viability while inhibiting the apoptosis of model OA cells. Additionally, quantitative real‐time PCR and Western blot assays showed that the exosomes derived from curcumin‐treated MSCs significantly restored the down‐regulated miR‐143 and miR‐124 expression as well as up‐regulated NF‐kB and ROCK1 expression in OA cells. Mechanistically, curcumin treatment decreased the DNA methylation of miR‐143 and miR‐124 promoters. In addition, the 3’ UTRs of NF‐kB and ROCK1 were proven to contain the binding sites for miR‐143 and miR‐124, respectively. Therefore, the up‐regulation of miR‐143 and miR‐124 in cellular and mouse OA models treated with exosomes remarkably restored the normal expression of NF‐kB and ROCK1. Consequently, the progression of OA was attenuated by the exosomes. Our results clarified the molecular mechanism underlying the therapeutic role of MSC‐derived exosomes in OA treatment.     

miRNA‐4317 suppresses human gastric cancer cell proliferation by targeting ZNF322

Studies have shown that miR‐4317 is dysregulated in tumor, but the biologic role of miR‐4317 in tumor development and progression remains unknown. The present study aimed to investigate the role of miR‐4317 in human gastric cancer. Quantitative real‐time PCR was used to quantify miR‐4317 expression levels in clinical gastric cancer specimens and cell lines. MTT, colony formation and cell cycle assays were performed to identify the contributions of miR‐4317 to cell proliferation in gastric cancer cell lines. The results showed that miR‐4317 was significantly decreased in 17 clinical gastric cancer specimens compared with adjacent non‐tumor stomach tissues. Forced expression of miR‐4317 suppressed gastric cancer cell proliferation and blocked S‐G2/M transition. Bioinformatics and dual‐luciferase reporter assays confirmed that ZNF322 is a direct target of miR‐4317. Silencing ZNF322 recapitulated the cellular and molecular effects seen upon miR‐4317 overexpression. These findings indicate that miR‐4317 represses the proliferation of gastric cancer cell, at least in part, by targeting and suppressing ZNF322 and that it may serve as a therapeutic target for gastric cancer treatment.     

LINC01303 functions as a competing endogenous RNA to regulate EZH2 expression by sponging miR‐101‐3p in gastric cancer

Long non‐coding RNA (lncRNA) is one of the important regulators of many malignancies. However, the biological function and clinical significance of a large number of lncRNAs in gastric cancer remain unclear. Therefore, we analysed the TCGA data to find that LINC01303 is significantly up‐regulated in gastric cancer tissues. However, the biological function of LINC01303 in GC remains unknown. In our study, we found that the expression of LINC01303 was significantly higher in GC tissues than in adjacent tissues by real‐time quantitative PCR. We can significantly inhibit the malignant proliferation, migration and invasion of GC cells by silencing LINC01303 expression. In addition, LINC01303 knockdown can also inhibit GC growth in vivo. After the bioinformatics analysis, we found that LINC01303 can be used as a miR‐101‐3p sponge to competitively adsorb miR‐101‐3p with EZH2. Therefore, our results indicate that LINC01303 promotes the expression of EZH2 by inhibiting miR‐101‐3p activity and promotes GC progression. In summary, in this study, we demonstrated for the first time that the LINC01303/miR‐101‐3p/EZH2 axis promotes GC progression.     

MicroRNA‐198 inhibition of HGF/c‐MET signaling pathway overcomes resistance to radiotherapy and induces apoptosis in human non–small‐cell lung cancer

Non–small‐cell lung cancer (NSCLC) is the most common cause of death from cancer worldwide. MicroRNAs (miRNAs) are a group of important regulators in NSCLC, including miR‐198. However, the underlying molecular mechanisms of miR‐198 involvement in intrinsic resistance to radiotherapy in NSCLC remain to be elucidated. In this study, to investigate the clinical significance of miR‐198 in NSCLC in relation to the response to radiotherapy, we determined the expression patterns of miR‐198 between responders and nonresponders after 2 months of radiotherapy and found that decreased expressions of miR‐198 were associated with radiotherapy resistance. In addition, we altered the endogenous miR‐198 using mimics or inhibitors to examine the effects of miR‐198 on 4‐Gy–irradiated A549 and SPCA‐1 cells in vitro. Upregulating miR‐198 was shown to inhibit cell proliferation, migration, and invasion and induce apoptosis. MiR‐198 inhibition produced a reciprocal result. PHA665752, a selective small‐molecule c‐Met inhibitor, potently inhibited hepatocyte growth factor (HGF)‐stimulated and constitutive c‐Met phosphorylation and rescued 4‐Gy–irradiated A549 and SPCA‐1 cells from miR‐198 inhibition. Most importantly, we established tumor xenografts of 4‐Gy–irradiated A549 and SPCA‐1 cells in nude mice and found that miR‐198 could suppress tumor formation. Hence, our data delineates the molecular pathway by which miR‐198 inhibits NSCLC cellular proliferation and induces apoptosis following radiotherapy, providing a novel target aimed at improving the radiotherapeutic response in NSCLC.     

miR‐655 suppresses epithelial‐to‐mesenchymal transition by targeting Prrx1 in triple‐negative breast cancer

Triple‐negative breast cancer (TNBC) is a highly aggressive breast cancer subtype that lacks effective targeted therapies. The epithelial‐to‐mesenchymal transition (EMT) is a key contributor in the metastatic process. In this study, we found that miR‐655 was down‐regulated in TNBC, and its expression levels were associated with molecular‐based classification and lymph node metastasis in breast cancer. These findings led us to hypothesize that miR‐655 overexpression may inhibit EMT and its associated traits of TNBC. Ectopic expression of miR‐655 not only induced the up‐regulation of cytokeratin and decreased vimentin expression but also suppressed migration and invasion of mesenchymal‐like cancer cells accompanied by a morphological shift towards the epithelial phenotype. In addition, we found that miR‐655 was negatively correlated with Prrx1 in cell lines and clinical samples. Overexpression of miR‐655 significantly suppressed Prrx1, as demonstrated by Prrx1 3′‐untranslated region luciferase report assay. Our study demonstrated that miR‐655 inhibits the acquisition of the EMT phenotype in TNBC by down‐regulating Prrx1, thereby inhibiting cell migration and invasion during cancer progression.     

Exosomal miR‐663b targets Ets2‐repressor factor to promote proliferation and the epithelial–mesenchymal transition of bladder cancer cells

Exosomes circulating in biological fluids have the potential to be utilized as cancer biomarkers and are associated with cancer progression and metastasis. MicroRNA (miR)‐663b has been found to be elevated in plasma from patients with bladder cancer (BC). However, the functional role of exosomal miR‐663b in BC processes remains unknown. Here, we isolated exosomes from plasma and found that the miR‐663b level was elevated in exosomes from plasma of patients with BC compared with healthy controls. Exosomal miR‐663b from BC cells promoted cell proliferation and epithelial–mesenchymal transition. Moreover, exosomal miR‐663b targeted Ets2‐repressor factor and acted as a tumor promoter in BC cells. Taken together, our findings suggested that exosomal miR‐663b is a promising potential biomarker and target for clinical detection and therapy in BC.     

MiR‐429 suppresses glioblastoma multiforme by targeting SOX2

Accumulating evidence has shown that miR‐429 plays an important role in the development and progression of tumour. However, the role of miR‐429 in glioblastoma multiforme (GBM) remains largely unknown. The present study is designed to investigate the function of miR‐429 in GBM and to explore the molecular mechanism underlying its function. The expression level of miR‐429 was detected in GBM tissues and cell lines by quantitative real‐time polymerase chain reaction. The effect of overexpression of miR‐429 on in vitro cell proliferation, apoptosis and invasion was examined. Western blot analysis was used to detect the influence of miR‐429 on the expression of target gene, and Pearson analysis was used to calculate the correlation between the expression of targets gene and the miR‐429 in GBM tissues. Our study shows that miR‐429 is downregulated in GBM tissues compared with noncancerous tissues (P < .01). In addition, the expression of miR‐429 in GBM cell lines is also significantly lower (P < .01). Enforced expression of miR‐429 inhibits GBM cells proliferation, induces apoptosis and suppresses invasion and leads to the downregulation of the SOX2 protein. Moreover, the expression level of miR‐429 in GBM tissues shows inverse relationship with the expression level of SOX2 protein. Our findings suggest that miR‐429 represents a potential tumour‐suppressive miRNA and plays an important role in GBM progression by directly targeting SOX2.     

MiRNA‐30a inhibits AECs‐II apoptosis by blocking mitochondrial fission dependent on Drp‐1

Apoptosis of type II alveolar epithelial cells (AECs‐II) is a key determinant of initiation and progression of lung fibrosis. However, the mechanism of miR‐30a participation in the regulation of AECs‐II apoptosis is ambiguous. In this study, we investigated whether miR‐30a could block AECs‐II apoptosis by repressing mitochondrial fission dependent on dynamin‐related protein‐1 (Drp‐1). The levels of miR‐30a in vivo and in vitro were determined through quantitative real‐time PCR (qRT‐PCR). The inhibition of miR‐30a in AECs‐II apoptosis, mitochondrial fission and its dependence on Drp‐1, and Drp‐1 expression and translocation were detected using miR‐30a mimic, inhibitor‐transfection method (gain‐ and loss‐of‐function), or Drp‐1 siRNA technology. Results showed that miR‐30a decreased in lung fibrosis. Gain‐ and loss‐of‐function studies revealed that the up‐regulation of miR‐30a could decrease AECs‐II apoptosis, inhibit mitochondrial fission, and reduce Drp‐1 expression and translocation. MiR‐30a mimic/inhibitor and Drp‐1 siRNA co‐transfection showed that miR‐30a could inhibit the mitochondrial fission dependent on Drp‐1. This study demonstrated that miR‐30a inhibited AECs‐II apoptosis by repressing the mitochondrial fission dependent on Drp‐1, and could function as a novel therapeutic target for lung fibrosis.     

Circular RNA hsa_circRNA_002178 silencing retards breast cancer progression via microRNA‐328‐3p‐mediated inhibition of COL1A1

Circular RNAs (circRNAs) are a group of non‐coding RNAs implicated in the pathogenesis of cancer progression, which exert their functions via regulation of microRNAs (miRNAs) and genes. The present study uses gain‐ and loss‐of‐function approaches to evaluate the functions of hsa_circRNA_002178 in angiogenesis along with energy metabolism and underlying downstream signals. The expression pattern of hsa_circRNA_002178 in clinical breast cancer tissues and its association with prognosis were characterized at first. Next, the energy metabolism and angiogenesis as well as cell viability were evaluated when the expression of hsa_circRNA_002178 in breast cancer cells was knocked down by siRNA. The interaction between hsa_circRNA_002178 and its downstream miR‐328‐3p was identified, followed by the analysis of their functions in regulation of breast cancer cellular behaviours. The target gene of miR‐328‐3p was predicted and verified, followed by identifying its role in the breast cancer progression. Higher expression of hsa_circRNA_002178 shared an association with worse prognosis in breast cancer. The inhibition of hsa_circRNA_002178 resulted in reductions in cell viability, energy metabolism and tube formation ability. Hsa_circRNA_002178 could competitively bind to miR‐328‐3p and down‐regulated its expression. Restoration of miR‐328‐3p eliminated the tumour‐promoting effects of hsa_circRNA_002178. COL1A1, as a target of miR‐328‐3p, could be up‐regulated by overexpression of hsa_circRNA_002178. In vivo experiments further confirmed the inhibition of tumour growth and inflammation by silencing hsa_circRNA_002178 or up‐regulating miR‐328‐3p. Taken together, hsa_circRNA_002178 is highlighted as a promising target for breast cancer due to the anti‐tumour effects achieved by silencing hsa_circRNA_002178.     

Circulating exosomal microRNA‐96 promotes cell proliferation,migration and drug resistance by targeting LMO7

Detection and treatment of lung cancer still remain a clinical challenge. This study aims to validate exosomal microRNA‐96 (miR‐96) as a serum biomarker for lung cancer and understand the underlying mechanism in lung cancer progression. MiR‐96 expressions in normal and lung cancer patients were characterized by qPCR analysis. Changes in cell viability, migration and cisplatin resistance were monitored after incubation with isolated miR‐96‐containing exosomes, anti‐miR‐96 and anti‐miR negative control (anti‐miR‐NC) transfections. Dual‐luciferase reporter assay was used to study interaction between miR‐96 and LIM‐domain only protein 7 (LMO7). Changes induced by miR‐96 transfection and LMO7 overexpression were also evaluated. MiR‐96 expression was positively correlated with high‐grade and metastatic lung cancers. While anti‐miR‐96 transfection exhibited a tumour‐suppressing function, exosomes isolated from H1299 enhanced cell viability, migration and cisplatin resistance. Potential miR‐96 binding sites were found within the 3′‐UTR of wild‐type LMO7 gene, but not of mutant LMO7 gene. LMO7 expression was inversely correlated with lung cancer grades, and LMO7 overexpression reversed promoting effect of miR‐96. We have identified exosomal miR‐96 as a serum biomarker of malignant lung cancer. MiR‐96 promotes lung cancer progression by targeting LMO7. The miR‐96‐LMO7 axis may be a therapeutic target for lung cancer patients, and new diagnostic or therapeutic strategies could be developed by targeting the miR‐96‐LMO7 axis.     

microRNA‐145‐3p inhibits non‐small cell lung cancer cell migration and invasion by targeting PDK1 via the mTOR signaling pathway

The mammalian target of rapamycin (mTOR) pathway is dysregulated in more than 50% of all human malignancies and is a major target in cancer treatment. In this study, we explored the underlying mechanism involving microRNA‐145‐3p (miR‐145‐3p) in the development and progression of non‐small cell lung cancer (NSCLC) by targeting PDK1 via the mTOR signaling pathway. NSCLC tissues and adjacent normal tissues were obtained from 83 NSCLC patients. miR‐145‐3p, PDK1, and mTOR levels were determined by quantitative real‐time polymerase chain reaction (qRT‐PCR) and immunohistochemistry. Human NSCLC cell lines A549 and H1299 were transfected with miR‐145‐3p and siPDK1 to confirm the effect of miR‐145‐3p and PDK1 on NSCLC cells in vitro. Cell growth was evaluated by a CCK8 assay. Cell motility and chemotaxis analysis were determined by the scratch test and chemotaxis assay, respectively. The protein levels of PDK1 and mTOR were measured using the western blotting. Results showed lower level of miR‐145‐3p and higher levels of PDK1 and mTOR in NSCLC tissues compared to the adjacent normal tissues. In vitro results showed that cell growth, cell motility, and chemotaxis were all inhibited in cells transfected with miR‐145‐3p and those transfected with siPDK. Additionally, dual luciferase reporter gene assay helped confirmed that PDK1 is a target of miR‐145. Finally, levels of PDK1, mTOR, and phosphorylated‐mTOR were lower in cells transfected with miR‐145‐3p as well as those with siPDK1. These findings indicate that miR‐145‐3p may inhibit cell growth, motility, and chemotaxis in NSCLC by targeting PDK1 through suppressing the mTOR pathway.