MicroRNA-491 is involved in metastasis of hepatocellular carcinoma by inhibitions of matrix metalloproteinase and epithelial to mesenchymal transition

Re-exploration of immunotherapy targeting EMT of hepatocellular carcinoma: Starting from the NF-κB pathway

Hepatocellular carcinoma (HCC) is the fifth most common malignancies worldwide, and its high morbidity and mortality have brought a heavy burden to the global public health system. Due to the concealment of its onset, the limitation of treatment, the acquisition of multi-drug resistance and radiation resistance, the treatment of HCC cannot achieve satisfactory results. Epithelial mesenchymal transformation (EMT) is a key process that induces progression, distant metastasis, and therapeutic resistance to a variety of malignant tumors, including HCC. Therefore, targeting EMT has become a promising tumor immunotherapy method for HCC. The NF-κB pathway is a key regulatory pathway for EMT. Targeting this pathway has shown potential to inhibit HCC infiltration, invasion, distant metastasis, and therapeutic resistance. At present, there are still some controversies about this pathway and new ideas of combined therapy, which need to be further explored. This article reviews the progress of immunotherapy in improving EMT development in HCC cells by exploring the mechanism of regulating EMT.

miRNAs and related genetic biomarkers according to the WHO glioma classification: From diagnosis to future therapeutic targets

In the 2021 WHO classification of Tumors of the Central Nervous System, additional molecular characteristics have been included, defining the following adult-type diffuse glioma entities: Astrocytoma IDH-mutant, Oligodendroglioma IDH-mutant and 1p/19q-codeleted, and Glioblastoma IDH-wildtype. Despite advances in genetic analysis, precision oncology, and targeted therapy, malignant adult-type diffuse gliomas remain "hard-to-treat tumors", indicating an urgent need for better diagnostic and therapeutic strategies. In the last decades, miRNA analysis has been a hotspot for researching and developing diagnostic, prognostic, and predictive biomarkers for various disorders, including brain cancer. Scientific interest has recently been directed towards therapeutic applications of miRNAs, with encouraging results. Databases such as NCBI, PubMed, and Medline were searched for a selection of articles reporting the relationship between deregulated miRNAs and genetic aberrations used in the latest WHO CNS classification. The current review discussed the recommended molecular biomarkers and genetic aberrations based on the 2021 WHO classification in adult-type diffuse gliomas, along with associated deregulated miRNAs. Additionally, the study highlights miRNA-based treatment advancements in adults with gliomas.

Harnessing function of EMT in hepatocellular carcinoma: From biological view to nanotechnological standpoint

Management of cancer metastasis has been associated with remarkable reduction in progression of cancer cells and improving survival rate of patients. Since 90% of mortality are due to cancer metastasis, its suppression can improve ability in cancer fighting. The EMT has been an underlying cause in increasing cancer migration and it is followed by mesenchymal transformation of epithelial cells. HCC is the predominant kind of liver tumor threatening life of many people around the world with poor prognosis. Increasing patient prognosis can be obtained via inhibiting tumor metastasis. HCC metastasis modulation by EMT and HCC therapy by nanoparticles are discussed here. First of all, EMT happens during progression and advanced stages of HCC and therefore, its inhibition can reduce tumor malignancy. Moreover, anti-cancer compounds including all-trans retinoic acid and plumbaging, among others, have been considered as inhibitors of EMT. The EMT association with chemoresistance has been evaluated. Moreover, ZEB1/2, TGF-β, Snail and Twist are EMT modulators in HCC and enhancing cancer invasion. Therefore, EMT mechanism and related molecular mechanisms in HCC are evaluated. The treatment of HCC has not been only emphasized on targeting molecular pathways with pharmacological compounds and since drugs have low bioavailability, their targeted delivery by nanoparticles promotes HCC elimination. Moreover, nanoparticle-mediated phototherapy impairs tumorigenesis in HCC by triggering cell death. Metastasis of HCC and even EMT mechanism can be suppressed by cargo-loaded nanoparticles.

Abnormal expression of SLIT3 induces intravillous vascularization dysplasia in ectopic pregnancy

Objective

To investigate whether the morphology, capillary number, and transcriptome expression profiles of ectopic pregnancy (EP) villi differ from those of normal pregnancy (NP) villi.

Methods

Hematoxylin-eosin (HE) and immunohistochemistry (IHC) staining for CD31 were conducted to compare differences in morphology and capillary number between EP and NP villi. Differentially expressed (DE) miRNAs and mRNAs were determined from transcriptome sequencing of both types of villi and used to construct a miRNA-mRNA network, from which hub genes were identified. Candidate DE-miRNAs and DE-mRNAs were validated by quantitative reverse transcription (qRT)-PCR. Correlations were identified between the number of capillaries and serum beta human chorionic gonadotropin (β-HCG) levels and between the expression levels of hub genes associated with angiogenesis and β-HCG levels.

Results

The mean and total cross-sectional areas of placental villi were significantly increased in EP compared with NP villi. Capillary density was greatly reduced in EP villi and was positively correlated with β-HCG levels. A total of 49 DE-miRNAs and 625 DE-mRNAs were identified from the sequencing data. An integrated analysis established a miRNA-mRNA network containing 32 DE-miRNAs and 103 DE-mRNAs. Based on the validation of hub mRNAs and miRNAs in the network, a regulatory pathway involving miR-491-5p-SLIT3 was discovered, which may have a role in the development of villous capillaries.

Conclusion

Villus morphology, capillary number, and miRNA/mRNA expression profiles in villous tissues were aberrant in EP placentas. Specifically, SLIT3, which is regulated by miR-491-5p, may contribute to the regulation of villous angiogenesis and was established as a putative predictor of chorionic villus development, providing a basis for future research.

The Role of miRNAs, circRNAs and Their Interactions in Development and Progression of Hepatocellular Carcinoma: An Insilico Approach

Hepatocellular carcinoma (HCC) is a type of malignant tumor. miRNAs are noncoding RNAs and their differential expression patterns are observed in HCC-induced by alcoholism, HBV and HCV infections. By acting as a competing endogenous RNA (ceRNA), circRNA regulates the miRNA function, indirectly controlling the gene expression and leading to HCC progression. In the present study, data mining was performed to screen out all miRNAs and circRNA involved in alcohol, HBV or HCV-induced HCC with statistically significant (≤0.05%) expression levels reported in various studies. Further, the interaction of miRNAs and circRNA was also investigated to explore their role in HCC due to various causative agents. Together, these study data provide a deeper understanding of the circRNA-miRNA regulatory mechanisms in HCC. These screened circRNA, miRNA and their interactions can be used as prognostic biomarkers or therapeutic targets for the treatment of HCC.

The Tumor Suppressor Roles and Mechanisms of MiR-491 in Human Cancers

MicroRNAs (miRNAs) are short non-coding RNAs that bind to the 3' untranslated region (3'' UTR) of target mRNAs to control gene expression post-transcriptionally. Recent indications have highlighted their important roles in a variety of pathophysiological conditions as well as human malignancies. Dysregulated miRNAs act as tumor suppressor genes or oncogenes in a variety of cancers. MiR-491 has been shown to have a major effect on tumorigenesis in multiple malignancies through binding to specific genes and signaling cascades, thereby preventing cancer progression. This review provides an overview of miR-491 expression in regulatory mechanisms and biological procedures of tumor cells, as well as the prospective possible treatment effects of various types of human cancers.

Low Expression of miR-491-3p Is Correlated with Lymph Node Metastasis in Gastric Cancer

Objective

MiR-491-3p, as a tumor suppressor miRNA, was found decreased in many solid tissues. In this study, we aim to investigate miR-491-3p expression in gastric cancer with or without lymph node metastasis (LNM).

Methods

GSE173215 dataset from Gene Expression Omnibus (GEO) was used to measure miRNA expression from tissue samples of gastric cancer patients. Moreover, gastric tumor tissues (non-LNM: n = 78; LNM: n = 68) were obtained to detect the miR-491-3p expression. Receiver operating characteristic (ROC) curve and Kaplan–Meier (KM) survival analysis, as well as Cox regression analysis, were performed to reveal the role of miR-491-3p in diagnosis and prognosis of gastric cancer.

Results

According to GSE173215 datasets (t = −11.25, adjust P value = 1.30E-06) and our clinical results (0.390 ± 0.193 vs. 0.562 ± 0.166, P < 0.005), the gastric cancer patients with LNM showed lower miR-491-3p expression than those without LNM, demonstrating a high diagnostic efficiency (sensitivity: 74.36%; specificity: 69.12%). In addition, both LNM and low miR-491-3p expression were correlated with the poor prognosis of gastric cancer. Furthermore, the LNM patient with low expression of miR-491-3p had the worse prognosis, but the non-LNM patient with high expression of miR-491-3p had the best prognosis. MiR-491-3p expression (HR = 0.003, 95%CI: 3.35E-04∼0.028) and LNM (HR = 2.326, 95%CI: 1.046∼5.173) were independent risk factors for gastric cancer.

Conclusion

Downregulated miR-491-3p expression was found in gastric cancer, being a high diagnostic efficiency and an independent risk factor for gastric cancer, especially in those having LNM.

The NEAT1_2/miR-491 Axis Modulates Papillary Thyroid Cancer Invasion and Metastasis Through TGM2/NFκb/FN1 Signaling

NEAT1 (nuclear paraspeckle assembly transcript 1) is an oncogenic long non-coding RNA (lncRNA) that facilitates tumorigenesis in multiple cancers. In papillary thyroid cancer (PTC), the molecular mechanism by which NEAT1 affects invasion and metastasis remains elusive. RNA sequencing was used to discover differentially expressed NEAT1_2 downstream genes. Protein and RNA expression analyses and immunohistochemistry detected the expression of NEAT1_2, Transglutaminase 2 (TGM2), and microRNA-491 (miR-491) among PTC and non-cancerous tissues. Transwell and wound healing assays, and a mouse model of lung metastasis were used for further functional analyses. Bioinformatics was performed to predict miRNAs binding to both NEAT1_2 and TGM2. Rescue experiments and dual-luciferase reporter assays were performed. In PTC tissues, NEAT1_2 expression was markedly increased and regulated TGM2 expression. TGM2 was overexpressed in PTC, correlating positively with exthyroidal extension and lymph node metastasis. TGM2 knockdown significantly inhibited invasion and metastasis. NEAT1_2 sponged miR-491, acting as a competing endogenous RNA to regulate TGM2 expression. Fibronectin 1 (FN1) was predicted as a TGM2 target. TGM2 could transcriptionally activate FN1 by promoting nuclear factor kappa B (NFκb) p65 nuclear translocation, ultimately promoting PTC invasion/metastasis. These findings identify that NEAT1_2 sponges miR-491 to regulate TGM2 expression. TGM2 activates FN1 via NFκb to promote PTC invasion and metastasis.

Role of microRNAs in Pressure Ulcer Immune Response, Pathogenesis, and Treatment

Pressure ulcers are preventable, yet highly prevalent, chronic wounds that have significant patient morbidity and high healthcare costs. Like other chronic wounds, they are characterized by impaired wound healing due to dysregulated immune processes. This review will highlight key biochemical pathways in the pathogenesis of pressure injury and how this signaling leads to impaired wound healing. This review is the first to comprehensively describe the current literature on microRNA (miRNA, miR) regulation of pressure ulcer pathophysiology.

MicroRNA dysregulation interplay with childhood abdominal tumors

Abdominal tumors (AT) in children account for approximately 17% of all pediatric solid tumor cases, and frequently exhibit embryonal histological features that differentiate them from adult cancers. Current molecular approaches have greatly improved the understanding of the distinctive pathology of each tumor type and enabled the characterization of novel tumor biomarkers. As seen in abdominal adult tumors, microRNAs (miRNAs) have been increasingly implicated in either the initiation or progression of childhood cancer. Moreover, besides predicting patient prognosis, they represent valuable diagnostic tools that may also assist the surveillance of tumor behavior and treatment response, as well as the identification of the primary metastatic sites. Thus, the present study was undertaken to compile up-to-date information regarding the role of dysregulated miRNAs in the most common histological variants of AT, including neuroblastoma, nephroblastoma, hepatoblastoma, hepatocarcinoma, and adrenal tumors. Additionally, the clinical implications of dysregulated miRNAs as potential diagnostic tools or indicators of prognosis were evaluated.

Ginsenoside Rh2 Inhibits Migration of Lung Cancer Cells under Hypoxia via mir-491

Background:

Ginsenoside Rh2 (Rh2), which is extracted from ginseng, exerts antitumor activity. Here we would like to study the role of Rh2 on hypoxia-induced migration in lung adenocarcinoma.

Methods:

Lung adenocarcinoma A549 and H1299 cells were cultured in 1% O2 condition to mimic the hypoxic tumor microenvironment. The migrations of cancer cells were measured by transwell assay and scratch assay.

Results:

Rh2 could inhibit hypoxia-induced A549 and H1299 cell migration via increase of mir-491 expression. Further, mir-491 antisense oligonucleotide could repress hypoxia-induced migration and the expression of matrix metalloproteinase (MMP)-9 expression in Rh2-treated A549 cells.

Conclusion:

These findings suggest that Rh2 exerts anti-metastasis activity in the hypoxic tumor microenvironment in lung adenocarcinoma cells via mir-491.

Genetic And Epigenetic Regulation Of E-Cadherin Signaling In Human Hepatocellular Carcinoma

E-cadherin is well known as a growth and invasion suppressor and belongs to the large cadherin family. Loss of E-cadherin is widely known as the hallmark of epithelial-to-mesenchymal transition (EMT) with the involvement of transcription factors such as Snail, Slug, Twist and Zeb1/2. Tumor cells undergoing EMT could migrate to distant sites and become metastases. Recently, numerous studies have revealed how the expression of E-cadherin is regulated by different kinds of genetic and epigenetic alteration, which are implicated in several crucial transcription factors and pathways. E-cadherin signaling plays an important role in hepatocellular carcinoma (HCC) initiation and progression considering the highly mutated frequency of CTNNB1 (27%). Combining the data from The Cancer Genome Atlas (TCGA) database and previous studies, we have summarized the roles of gene mutations, chromosome instability, DNA methylation, histone modifications and non-coding RNA in E-cadherin in HCC. In this review, we discuss the current understanding of the relationship between these modifications and HCC. Perspectives on E-cadherin-related research in HCC are provided.

Reversal of sorafenib resistance in hepatocellular carcinoma: epigenetically regulated disruption of 14-3-3η/hypoxia-inducible factor-1α

Sorafenib resistance is one of the main obstacles to the treatment of advanced/recurrent hepatocellular carcinoma (HCC). Here, sorafenib-resistant HCC cells and xenografts in nude mice were used as experimental models. A cohort of patients with advanced recurrent HCC who were receiving sorafenib therapy was used to assess the clinical significance of this therapy. Our data showed that 14-3-3η maintained sorafenib resistance in HCC. An analysis of the underlying molecular mechanisms revealed that 14-3-3η stabilizes hypoxia-inducible factor 1α (HIF-1α) through the inhibition of ubiquitin-dependent proteasome protein degradation, which leads to the maintenance of cancer stem cell (CSC) properties. We further found that microRNA-16 (miR-16) is a competent miRNA that reverses sorafenib resistance by targeting the 3'-UTR of 14-3-3η and thereby inhibits 14-3-3η/HIF-1α/CSC properties. In HCC patients, significant negative correlations were found between the expression of miR-16 and 14-3-3η, HIF-1α, or CSC properties. Further analysis showed that low miR-16 expression but high 14-3-3η expression can prognosticate sorafenib resistance and poor survival. Collectively, our present study indicated that miR-16/14-3-3η is involved in sorafenib resistance in HCC and that these two factors could be potential therapeutic targets and biomarkers for predicting the response to sorafenib treatment.

Aspirin enhances the sensitivity of hepatocellular carcinoma side population cells to doxorubicin via miR-491/ABCG2

Objective: To explore whether aspirin (ASA) enhances the sensitivity of hepatocellular carcinoma (HCC) side population (SP) cells to doxorubicin (Doxo) via miR-491/ATP-binding cassette sub-family G member 2 (ABCG2).Methods: Non-SP and SP cells were isolated from MHCC-97L cell line using flow cytometry analysis and fluorescence-activated cell sorting. Colony formation assay was performed to determine the colony-formation ability of cells. Cell viability of SP cells was determined with the MTT assay. Luciferase reporter assay was applied in confirming the binding between miR-491 and ABCG2.Results: Although the Doxo treatment lowered the colony-formation ability of both non-SP and SP cells, the colony-formation ability of SP cells was 2-fold higher than that of non-SP cells (P<0.05). Doxo slightly inhibited the cell viability of SP cells in a concentration-dependent manner; the addition of ASA dramatically enhanced the inhibitory effect of Doxo on SP cell viability in a concentration-dependent manner (P<0.05). Compared with non-SP cells, the miR-491 expression was significantly decreased in SP cells, which was significantly reversed by ASA (P<0.05). miR-491 directly controlled the ABCG2 expression. In the presence of Doxo, miR-491 inhibitor reduced the inhibitory effect of ASA on the cell viability of SP cells, which was significantly reversed by knockdown of ABCG2 (P<0.05).Conclusion: ASA enhanced the sensitivity of SP cells to Doxo via regulating the miR-491/ABCG2 signaling pathway.

Micro-RNAs as critical regulators of matrix metalloproteinases in cancer

Metastasis is known to be one of the important factors associated with cancer-related deaths worldwide. Several cellular and molecular targets are involved in the metastasis process. Among these targets, matrix metalloproteinases (MMPs) play central roles in promoting cancer metastasis. MMPs could contribute toward tumor growth, angiogenesis, migration, and invasion via degradation of the extracellular matrix and activation of pre-pro-growth factors. Therefore, identification of various cellular and molecular pathways that affect MMPs could contribute toward a better understanding of the metastatic pathways involved in various tumors. Micro-RNAs are important targets that could affect MMPs. Multiple lines of evidence have indicated that deregulation of various micro-RNAs, including miR-9, Let-7, miR-10b, and miR-15b, affects metastasis of tumor cells via targeting MMPs.

Extracellular vesicles mediate low dose ionizing radiation-induced immune and inflammatory responses in the blood

PURPOSE

Radiation-induced bystander effects (RIBE) imply the involvement of complex signaling mechanisms, which can be mediated by extracellular vesicles (EVs). Using an in vivo model, we investigated EV-transmitted RIBE in blood plasma and radiation effects on plasma EV miRNA profiles.

MATERIALS AND METHODS

C57Bl/6 mice were total-body irradiated with 0.1 and 2 Gy, bone marrow-derived EVs were isolated, and injected systemically into naive, 'bystander' animals. Proteome profiler antibody array membranes were used to detect alterations in plasma, both in directly irradiated and bystander mice. MiRNA profile of plasma EVs was determined by PCR array.

RESULTS

M-CSF and pentraxin-3 levels were increased in the blood of directly irradiated and bystander mice both after low and high dose irradiations, CXCL16 and lipocalin-2 increased after 2 Gy in directly irradiated and bystander mice, CCL5 and CCL11 changed in bystander mice only. Substantial overlap was found in the cellular pathways regulated by those miRNAs whose level were altered in EVs isolated from the plasma of mice irradiated with 0.1 and 2 Gy. Several of these pathways have already been associated with bystander responses.

CONCLUSION

Low and high dose effects overlapped both in EV-mediated alterations in signaling pathways leading to RIBE and in their systemic manifestations.

Methylation-associated silencing of microRNA-129-3p promotes epithelial-mesenchymal transition, invasion and metastasis of hepatocelluar cancer by targeting Aurora-A

Metastasis and recurrence has become one major obstacle for further improving the survival of hepatocelluar cancer (HCC) patients. Therefore, it is critical to elucidate the mechanisms involved in HCC metastasis. This study aimed to investigate the roles of microRNA (miR)-129-3p in HCC metastasis and its possible molecular mechanisms. By using microarray analysis to compare levels of different miRNAs in HCC tissues with or without lymph node metastasis (LNM), we showed that HCC tissues with LNM had reduced levels of miR-129-3p, which was related to its promoter hypermethylation and correlated with tumor metastasis, recurrence and poor prognosis. Gain - and loss - of - function assays indicated that re-expression of miR-129-3p could reverse epithelial-mesenchymal transition (EMT), and reduce in vitro invasion and in vivo metastasis of HCC cells. Aurora-A, a serine/threonine protein kinase, was identified as a direct target of miR-129-3p. Knockdown of Aurora-A phenocopied the effect of miR-129-3p overexpression on HCC metastasis. In addition, Aurora-A upregulation could partially rescue the effect of miR-129-3p. We further demonstrated that activation of PI3K/Akt and p38-MAPK signalings were involved in miR-129-3p-mediated HCC metastasis. These findings suggest that methylation-mediated miR-129-3p downregulation promotes EMT, in vitro invasion and in vivo metastasis of HCC cells via activation of PI3K/Akt and p38-MAPK signalings partially by targeting Aurora-A. Therefore, miR-129-3p may be a novel prognostic biomarker and potential therapeutic target for HCC.

Methylation-mediated repression of microRNA-129-2 suppresses cell aggressiveness by inhibiting high mobility group box 1 in human hepatocellular carcinoma

Aberrant expression of microRNAs (miRNAs) and its dysfunction have been revealed as crucial modulators of cancer initiation and progression. MiR-129-2 has been reported to play a tumor suppressive role in different human malignancies. Here, we demonstrated that miR-129-2 was significantly decreased in hepatocellular carcinoma (HCC) tissues and cell lines. Furthermore, miR-129-2 was expressed at significant lower levels in aggressive and recurrent tumor tissues. Clinical analysis indicated that miR-129-2 expression was inversely correlated with venous infiltration, high Edmondson-Steiner grading and advanced tumor-node-metastasis (TNM) stage in HCC. Notably, miR-129-2 was an independent prognostic factor for indicating overall survival (OS) and disease-free survival (DFS) of HCC patients. Ectopic expression of miR-129-2 inhibited cell migration and invasion in vitro and in vivo. Furthermore, we confirmed that high mobility group box 1 (HMGB1) was a direct target of miR-129-2, and it abrogated the function of miR-129-2 in HCC. Mechanistic investigations showed that miR-129-2 overexpression inhibited AKT phosphorylation at Ser473 and decreased the expression of matrix metalloproteinase2/9 (MMP2/9). Upregulation of p-AKT abolished the decreased cell migration and invasion induced by miR-129-2 in HCC. Whereas inhibition of Akt phosphorylation significantly decreased HMGB1-enhanced HCC cell migration and invasion. Moreover, we found that miR-129-2 was downregulated by DNA methylation, and demethylation of miR-129-2 increased miR-129-2 expression in HCC cells and resulted in significant inhibitory effects on cell migration and invasion. In conclusion, miR-129-2 may serve as a prognostic indicator for HCC patients and exerts tumor suppressive role, at least in part, by inhibiting HMGB1.

MicroRNA-124a inhibits cell proliferation and migration in liver cancer by regulating interleukin-11

Liver cancer is the sixth most common malignant tumour and ranks in the top three cancers with regard to mortality due to metastasis and postsurgical recurrence. It is significant to understand the mechanisms underlying liver cancer for diagnosis and treatment. Cumulative evidence suggests that the abnormal regulation of microRNAs (miRNAs/miRs) may contribute to the development and metastasis of cancer. miR‑124a acts as a tumour suppressor in osteosarcoma, endometrial carcinoma, prostate cancer, and glioblastoma. However, the effects of miR‑124a in liver cancer and its biological mechanism are not fully understood. It has been demonstrated that miR‑124a is downregulated and interleukin (IL)‑11 is upregulated in the liver cancer tissues. In the present study, miR‑124a upregulation inhibited cell proliferation, migration and promoted cell apoptosis. Through a dual‑luciferase reporter assay, it was verified that IL‑11 is a direct target of miR‑124a. Furthermore, the overexpression of miR‑124a repressed the secretion of IL‑11 from hepatoma cells. Finally, it was identified that mimics of miR‑124a increased the expression of tissue inhibitor of matrix metalloproteinase‑2 (TIMP‑2) and Caspase‑3 and decreased the expression levels of matrix metalloproteinase 2 (MMP2), MMP9, B‑cell lymphoma 2, signal transducer and activator of transcription 3 (STAT3), and phosphorylated‑STAT3. In conclusion, the results indicated that miR‑124a has an important role as a tumour suppressor gene by targeting IL‑11. These findings may provide novel insights for clinical treatments to prevent the development of liver cancer.

Upregulated long non-coding RNA LOC90784 promotes cell proliferation and invasion and is associated with poor clinical features in HCC

A growing amount of literature has indicated that long non-coding RNAs (lncRNAs) are important factors in hepatocellular carcinoma (HCC) progression. However, the significance of lncRNAs in the progression and prognosis of liver cancer is largely unknown. In the present study, upregulated lncRNA LOC90784 was identified through integrative analysis of GSE58043 and GSE55191. Furthermore, associations between LOC90784 expression and the clinicopathological characteristics of patients were analyzed with a validated cohort 1 and the Cancer Genome Atlas (TCGA) cohort 2. We investigated the mechanisms by which this highly expressed lncRNA promotes HCC proliferation, invasion and migration via qRT-PCR, fluorescence in situ hybridization (FISH) staining, siRNA transfection, cell proliferation assays, Transwell and colony formation assays, flow cytometry analysis and Western blot. The results showed that LOC90784 expression levels were significantly higher in HCC cell lines and tissues and mainly localized in the cytoplasm. Knockdown of lncRNA LOC90784 expression inhibited proliferation and induced apoptosis and cell cycle arrest by promoting Bax and repressing CDK4 and Cyclin D1 protein expression; it also inhibited invasion and migration by repressing MMP2 and MMP9 expression in HCC cells. LOC90784 overexpression was associated with poor clinical features in the two cohorts and poor overall survival rates in HCC patients with clear resection margins (R0) in cohort 2. These results indicated that LOC90784 upregulation may be a critical oncogene and potential new biomarker in HCC.

miR-491-5p, mediated by Foxi1, functions as a tumor suppressor by targeting Wnt3a/β-catenin signaling in the development of gastric cancer

Accumulated evidence has suggested that microRNAs (miRNAs) have an important role in tumor development and progression by regulating diverse signaling pathways. However, the precise role of miRNAs in gastric cancer (GC) has not been elucidated. In this study, we describe the function and regulation network of miR-491-5p in GC. miR-491-5p is frequently downregulated in GC tissues compared with adjacent non-cancerous tissues. Forced expression of miR-491-5p significantly inhibits proliferation and colony formation, and promotes apoptosis in GC cells. Through bioinformatic analysis and luciferase assays, we confirm that miR-491-5p targets Wnt3a. Silencing Wnt3a inhibits cell proliferation and induces apoptosis. Similarly, restoration of Wnt3a counteracts the effects of miR-491-5p expression. Moreover, bioinformatic and luciferase assays indicate that the expression of miR-491-5p is regulated by Foxi1, which binds to its promoter and activates miR-491-5p expression. In conclusion, to the best of our knowledge, our findings are the first to demonstrate that Foxi1 is a key player in the transcriptional control of miR-491-5p and that miR-491-5p acts as an anti-oncogene by targeting Wnt3a/β-catenin signaling in GC. Our study reveals that Foxi1/miR-491-5p/Wnt3a/β-catenin signaling is critical in the progression of GC. Targeting the pathway described in this study may open up new prospects to restrict the progression of GC.

Ginsenoside Rh2 Targets EGFR by Up-Regulation of miR-491 to Enhance Anti-tumor Activity in Hepatitis B Virus-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most aggressive tumors in humans. The typical therapeutic strategies include a combination of chemotherapy, radiotherapy, and surgery, whereas the survival rate of patients is very poor. Ginsenoside Rh2 has been reported to have therapeutic effects on some tumors, but its effect on HCC has not been extensively evaluated. Here, we show that ginsenoside Rh2 can effectively inhibit the proliferation and cell survival of HCC cells in vitro and in a mouse model. Moreover, the inhibition of the tumor growth appears to result from combined effects on decreased tumor cell proliferation and cell viability. Further analyses suggest that ginsenoside Rh2 may have its anti-tumor effect through inhibition of epidermal growth factor receptor (EGFR) signaling pathway. Recombinant EGFR was given together with ginsenoside Rh2 to the tumor cells, which completely blocked the anti-tumor effect of ginsenoside Rh2. Our data also show that miR-491 is up-regulated in SMMC-7721 cells after Rh2 treatment. There is a negative correlation between EGFR and miR-491 levels in SMMC-7721 cells and miR-491 directly targeted EGFR at translational level. Our data not only reveal an anti-tumor effect of ginsenoside Rh2 but also demonstrate that this effect may function via activation and inhibition of EGFR signaling in HCC cells. The results suggest miR-491 can be a promising regulatory factor in EGFR signal transduction.

miR-491 regulates glioma cells proliferation by targeting TRIM28 in vitro

Background

MicroRNAs are significantly involved in tumorigenesis and progression of glioma. However, the critical part they play in glioma have not been fully elaborated. miR-491 and Tripartite motif containing 28 (TRIM28) are reported to aberrantly express in glioblastoma multiforme (GBM). Here, we detected miR-491 and TRIM28 expression and function in glioma cells.

Methods

We analyzed miR-491 expressions in 20 primary human GBM tissues and 6 control brain tissues by qRT-PCR assays and searched for The Cancer Genome Atlas (TCGA) database. Then we predicted possible mRNA target of miR-491 by TargetScan/MicroRNA and confirmed it via luciferase reporter assays. Knock-down of miR-491 and transfection of pLenti-TRIM28 were performed in U251 and U87 cells. Proliferation ability was examined by MTT and clone formation assays.

Results

miR-491 expression was obviously reduced in GBM cells and tissues. There was a positive correlation between the down-regulation of miR-491 and poor prognosis. Spearman’s correlation analysis demonstrated that miR-491 expression was negatively correlated with TRIM28 protein level. Possible mRNA binding sites of miR-491 predicted by TargetScan/MicroRNA were proved by luciferase assays. Clone formation and MTT assays indicated that up-regulation of miR-491 inhibited the proliferation of glioma cells.

Conclusions

miR-491 regulates glioma cells proliferation in vitro by targeting TRIM28.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-016-0769-y) contains supplementary material, which is available to authorized users.

The roles of microRNAs related with progression and metastasis in human cancers

Metastasis is an important factor in predicting the prognosis of the patients with cancers and contributes to high cancer-related mortality. Recent studies indicated that microRNAs (miRNAs) played a functional role in the initiation and progression of human malignancies. MicroRNAs are small non-coding RNAs of about 22 nucleotides in length that can induce messenger RNA (mRNA) degradation or repress mRNA translation by binding to the 3' untranslated region (3'-UTR) of their target genes. Overwhelming reports indicated that miRNAs could regulate cancer invasion and metastasis via epithelial-to-mesenchymal transition (EMT)-related and/or non-EMT-related mechanisms. In this review, we concentrate on the underlying mechanisms of miRNAs in regulating cancer progression and metastasis.

Up-regulation of microRNA-491-5p suppresses cell proliferation and promotes apoptosis by targeting FOXP4 in human osteosarcoma

BACKGROUND AND OBJECTIVES

MicroRNAs are small non-coding RNAs involved in pathogenesis and progression of human malignancies. MicroRNA-491-5p (miR-491-5p) is down-regulated in many human cancers where it would serve as a tumour suppressor. However, the role played by miR-491-5p in pathogenesis of human osteosarcoma has remained largely unknown. This study has been conducted to examine effects of miR-491-5p on migration and proliferation of cells of the SAOS-2 and MG63 osteosarcoma lines, and mechanisms of those effects.

MATERIALS AND METHODS

Levels of miR-491-5p expression in osteosarcoma tissues and in human osteosarcoma cell lines were studied using qualitative real-time polymerase chain reaction (qRT-PCR) methods. Cell viability was detected using the CCK-8 and EdU assays, while the transwell assay was used to evaluate migration and invasion. Apoptosis was analysed uing flow cytometry and the Hoechst 33342 nuclear staining method. A dual-luciferase reporter system was used to confirm the target gene of miR-491-5p. The electrophoretic mobility shift assay (EMSA) with DIG-labelled double-stranded FOXP4 oligonucleotides was used to confirm whether or not miR-491-5p suppressed FOXP4 activation.

RESULTS

Cells of osteosarcoma tissues and cell lines had low levels of miR-491-5p expression, but high levels of forkhead-box P4 (FOXP4) expression. Transfection of SAOS-2 and MG63 cells with miR-491-5p mimics inhibited expression of FOXP4 protein, which suppressed cell growth and migration, but induced apoptosis. Dual-luciferase reporter assays confirmed FOXP4 as the target gene for miR-491-5p. Overexpression of miR-491-5p suppressed FOXP4 activity in SAOS-2 and MG63 cells. Knockdown of FOXP4 in SAOS-2 and MG63 cells using an RNAi strategy resulted in reduced levels of cell proliferation and migration, but increased levels of apoptosis.

CONCLUSION

Our in vitro studies showed that up-regulation of miR-491-5p suppressed proliferation of the human osteosarcoma cells and induced apoptosis by targeting FOXP4. These findings suggest that miR-491-5p could be further studied as a potential clinical diagnostic or predictive biomarker for human osteosarcoma.

Targeting EMP3 suppresses proliferation and invasion of hepatocellular carcinoma cells through inactivation of PI3K/Akt pathway

Epithelial membrane protein-3 (EMP3), a typical member of the epithelial membrane protein (EMP) family, is epigenetically silenced in some cancer types, and has been proposed to be a tumor suppressor gene. However, its effects on tumor suppression are controversial and its roles in development and malignancy of hepatocellular carcinoma (HCC) remain unclear. In the present study, we found that EMP3 was highly expressed in the tumorous tissues comparing to the matched normal tissues, and negatively correlated with differentiated degree of HCC patients. Knockdown of EMP3 significantly reduced cell proliferation, arrested cell cycle at G1 phase, and inhibited the motility and invasiveness in accordance with the decreased expression and activity of urokinase plasminogen activator (uPA) and matrix metalloproteinase 9 (MMP-9) in HCC cells. The in vivo tumor growth of HCC was effectively suppressed by knockdown of EMP3 in a xenograft mouse model. The EMP3 knockdown-reduced cell proliferation and invasion were attenuated by inhibition of phosphatidylinositol 3-kinase (PI3K) or knockdown of Akt, and rescued by overexpression of Akt in HCC cells. Clinical positive correlations of EMP3 with p85 regulatory subunit of PI3K, p-Akt, uPA, as well as MMP-9 were observed in the tissue sections from HCC patients. Here, we elucidated the tumor progressive effects of EMP3 through PI3K/Akt pathway and uPA/MMP-9 cascade in HCC cells. The findings provided a new insight into EMP3, which might be a potential molecular target for diagnosis and treatment of HCC.

MicroRNA-451: epithelial-mesenchymal transition inhibitor and prognostic biomarker of hepatocelluar carcinoma

Increasing evidence indicates that dysregulation of microRNAs (miRNAs) plays critical roles in malignant transformation and tumor progression. Previously, we have shown that microRNA-451 (miR-451) inhibits growth, increases chemo- or radiosensitivity and reverses epithelial to mesenchymal transition (EMT) in lung cancer. However, the roles of miR-451 in hepatocelluar carcinoma (HCC) progression and metastasis are still largely unknown. Reduced miR-451 in HCC tissues was observed to be significantly correlated with advanced clinical stage, metastasis and worse disease-free or overall survival. Through gain- and loss-of function experiments, we demonstrated that miR-451 inhibited cell growth, induced G0/G1 arrest and promoted apoptosis in HCC cells. Importantly, miR-451 could inhibit the migration and invasion in vitro, as well as in vivo metastasis of HCC cells through regulating EMT process. Moreover, the oncogene c-Myc was identified as a direct and functional target of miR-451 in HCC cells. Knockdown of c-Myc phenocopied the effects of miR-451 on EMT and metastasis of HCC cells, whereas overexpression of c-Myc partially attenuated the functions of miR-451 restoration. Furthermore, miR-451 downregulation-induced c-Myc overexpression leads to the activation of Erk1/2 signaling, which induces acquisition of EMT phenotype through regulation of GSK-3β/snail/E-cadherin and the increased expression of MMPs family members in HCC cells. Collectively, these data demonstrated that miR-451 is a novel prognostic biomarker for HCC patients and that function as a potential metastasis inhibitor in HCC cells through activation of the Erk1/2 signaling, at least partially by targeting c-Myc. Thus, targeting miR-451/c-Myc/Erk1/2 axis may be a potential strategy for the treatment of metastatic HCC.

The PDGF-D/miR-106a/Twist1 pathway orchestrates epithelial-mesenchymal transition in gemcitabine resistance hepatoma cells

Emerging evidence demonstrates that platelet-derived growth factor-D (PDGF-D) plays a critical role in epithelial-mesenchymal transition (EMT) and drug resistance in hepatocellular carcinoma (HCC) cells. However, the underlying mechanism has not been fully elucidated. The objective is to explore the molecular mechanism of PDGF-D-mediated EMT in drug resistance HCC cells. To achieve our goal, we used multiple approaches including Western blotting, real-time RT-PCR, wound healing assay, invasion assay, luciferase activity assay, transfection, and immunohistochemistry. We found that PDGF-D is highly expressed in gemcitabine-resistant (GR) HCC cells. Moreover, PDGF-D markedly inhibited miR-106a expression and subsequently upregulated Twist1 expression. Notably, PDGF-D expression was associated with miR-106a and Twist1 in HCC patients. Our findings provide a possible molecular mechanism for understanding GR chemoresistance in HCC cells. Therefore, inactivation of PDGF-D/Twist or activation of miR-106a could be a novel strategy for the treatment of HCC.

Identification of miRNAs and differentially expressed genes in early phase non-small cell lung cancer

To explore the potential therapeutic targets of early‑stage non-small cell lung cancer (NSCLC), gene microarray analysis was conducted. The microarray data of NSCLC in stage IA, IB, IIA, and IIB (GSE50081), were downloaded from the Gene Expression Omnibus (GEO) database. The differentially expressed genes (DEGs) in IB vs. IA, IIA vs. IB, IIB vs. IIA were screened out via R. ToppGene Suite was used to get the enriched Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the DEGs. The GeneCoDis3 database and Cytoscape software were used to construct the transcriptional regulatory network. In total, 25, 17 and 14 DEGs were identified in IB vs. IA, IIA vs. IB, IIB vs. IIA of NSCLC, respectively. Some GO terms and pathways (e.g., extracellular space, alveolar lamellar body, bioactivation via cytochrome P450 pathway) were found significantly enriched in DEGs. Genes S100P, ALOX15B, CCL11, NLRP2, SERPINA3, FoxO4 and hsa-miR-491 may play important roles in the development of early-stage NSCLC. Thus, by bioinformatics analysis the key genes and biological processes involving in the development of early-stage NSCLC could be established, providing more potential references for the therapeutic targets.

The effects of silibin administration for different time periods on mouse liver with Ehrlich ascites carcinoma

BACKGROUND

Ehrlich ascites carcinoma is the one of the animal cancer models having high malignancy and rapid growth resistance. Silibin has reported to be an antioxidant in previous studies. We aimed to investigate the effects of silibin on mouse liver with Ehrlich ascites tumor (EAT) cells in different time periods.

METHODS

Balb/c mice were divided into five groups. Group I (Control): The saline buffer (sb) was injected intraperitoneally (ip) to the mice for 15 days. Group II (Silibin): 150mg/kg silibin was injected ip for 15 days. Group III (Ehrlich): 2×10(5) cells were transferred from the donor mouse to healthy mice on first day. Group IV (Ehrlich+Silibin): Silibin was given between 5th and 15th days to mice inoculated with EAT. Group V (Silibin+Ehrlich): Silibin was injected for 15 days after EAT cells. The liver sections were stained with matrix metalloproteinase-2 and -9 (MMP-2 and MMP-9), caspase 3, caspase 8, and proliferating cell nuclear antigen (PCNA) antibodies by the streptavidin-biotin-peroxidase technique. Biochemical analysis and Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) method were performed in the liver.

RESULTS

Superoxide dismutase levels of liver increased in Ehrlich+Silibin group compared with Ehrlich group. Malondialdehyde levels significantly decreased in Silibin+Ehrlich group compared with Ehrlich+Silibin. MMP-2 and MMP-9 immunopositive cells increased in Silibin+Ehrlich compared with Ehrlich group. Caspase 3 and TUNEL signals significantly increased in Silibin+Ehrlich group compared with Ehrlich group. PCNA positive signals significantly increased in Ehrlich+Silibin group compared with Ehrlich group.

CONCLUSION

According to our findings, we suggest that silibin treatment after EAT cells inoculation has more effective than concurrently EAT and silibin treatment.

Molecular mechanisms of microRNAs in regulating epithelial-mesenchymal transitions in human cancers

The epithelial-mesenchymal transition (EMT) provides a strong driving force in the progression of various human cancers and the development of chemoresistance. Recently, numbers of studies have demonstrated that microRNAs (miRNAs), by post-transcriptionally silencing EMT-related molecules, can promote or inhibit the EMT process and play pivotal roles in effectively manipulating the occurrence, development, invasion, and metastasis of cancers. MiRNAs can also control the EMT or be controlled by genetic modification and mutual regulation, especially negative feedback. Therefore, miRNAs can be viewed as either oncogenes or tumor suppressor genes to facilitate or retard the EMT, resulting in far-reaching impact on tumor metastasis and effective diagnosis, treatment, and prognosis.

MicroRNAs involved with hepatocellular carcinoma (Review)

Hepatocellular carcinoma (HCC) is one of the most common malignancies, which accounts for 90% of primary liver cancer. HCC usually presents with poor outcomes due to the high rates of tumor recurrence and widespread metastasis. However, the underlying mechanism of HCC initiation and progression, which significantly hindered the development of valid approaches for early detection and treatment remain to be elucidated. As a group of small non-coding RNAs, microRNAs (miRNAs) have been demonstrated to be involved in many types of diseases especially human malignancies. Numerous miRNAs are deregulated in HCC, which may shed some light on current investigations. Since miRNAs are stable and detected easily, their ectopic expression has been reported in HCC tissues, serum/plasma and cell lines. As previously described, miRNAs serve as tumor suppressors or oncogenes, indicating that miRNAs may be useful as diagnostic, therapeutic and prognostic markers of HCC. In the present review, we assessed the latest data regarding dysregulated miRNAs in HCC and reviewed the reported functions of these miRNAs as they apply to the diagnosis and prognosis of HCC.

MicroRNA-491-5p suppresses cervical cancer cell growth by targeting hTERT

MicroRNAs (miRNAs) are small non-coding RNAs that have been shown to regulate a variety of biological processes by targeting messenger RNA. MicroRNA-491-5p (miR-491-5p), an important miRNA, has been demonstrated to be involved in the processes of initiation and progression in several tumors. However, the precise biological function of miR-491-5p and its molecular mechanism in cervical cancer cells remain elusive. The present study was carried out to investigate the clinical significance and prognostic value of miR-491-5p expression in cervical cancer, and to evaluate the role of miR-491-5p and the underlying molecular mechanisms involved in cervical cancer. The results showed that miR-491-5p expression was significantly downregulated in cervical cancer tissues when compared with the corresponding adjacent normal tissues (P<0.001), and the value was negatively associated with advanced International Federation of Gynecology and Obstetrics (FIGO) stage, high histological grading and lymph node metastasis (P<0.01). The enforced expression of miR-491-5p in cervical cancer cells significantly inhibited proliferation, migration and invasion, induced cell apoptosis, and suppressed the tumor growth of the mouse model of HeLa cells. In addition, the dual-luciferase reporter assay revealed that human telomerase reverse transcriptase (hTERT) was identified as a novel target gene of miR-491-5p. Notably, it was found that miR-491-5p regulated the PI3K/AKT signaling pathway. These results suggested that targeting miR-491-5p is a strategy for blocking the development of cervical cancer.

miR-491-5p functions as a tumor suppressor by targeting JMJD2B in ERα-positive breast cancer

The involvement of miR-491-5p in breast cancer development is unclear. This study showed that miR-491-5p is significantly downregulated in ERα-positive breast cancer tissues and cell lines and is generally hypermethylated in ERα-positive breast cancer. MiR-491-5p overexpression significantly suppressed estrogen signaling and estrogen-stimulated proliferation of breast cancer cells. Furthermore, the histone demethylase JMJD2B was identified as a direct target of miR-491-5p. The ectopic expression of JMJD2B abrogated the phenotypic changes induced by miR-491-5p in breast cancer cells. Collectively, our data indicate that miR-491-5p plays a tumor suppressor role in the development and progression of breast caner and may be a novel therapeutic target against ERα-positive breast cancer.

Inhibition of the cancer stem cells-like properties by arsenic trioxide, involved in the attenuation of endogenous transforming growth factor beta signal

The elevation of cancer stem cells (CSCs)-like properties is involved in the initiation and progression of various human cancers. Current standard practices for treatment of cancers are less than satisfactory because of CSCs-mediated recurrence. For this reason, targeting the CSCs or the cancer cells with CSCs-like properties has become the new approach for the cancer treatments. In addition to treating leukemia, arsenic trioxide (As₂O₃) also suppresses other solid tumors. However, the roles of As₂O₃ in the regulation of CSCs-like properties remain largely uninvestigated. Here by using sphere formation assay, luciferase reporter assay, and some other molecular biology approaches, we found that As₂O₃ attenuated the CSCs-like properties in human hepatocellular carcinoma (HCC). Briefly, in HCC cells and mice xenograft models, As₂O₃ improved the expression of miR-491 by DNA-demethylation. MiR-491, which targeted the SMAD3-3'-UTR, decreased the expressions of SMAD3, and inhibited the CSCs-like properties in HCC cells. Knockdown of either miR-491 or SMAD3 attenuated the As₂O₃-induced inhibition of endogenous transforming growth factor beta signal and the CSCs-like properties. Further, in HCC patients, miR-491 is inversely correlated with the expressions of SMAD3, CD133, and the metastasis/recurrence outcome. By understanding a novel mechanism whereby As₂O₃ inhibits the CSCs-like properties in HCC, our study would help in the design of future strategies of developing As₂O₃ as a potential HCC chemopreventive agent when used alone or in combination with other current drugs.

Inhibition of TGF-β/SMAD3/NF-κB signaling by microRNA-491 is involved in arsenic trioxide-induced anti-angiogenesis in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. Current standard practices for treatment of HCC are less than satisfactory because of metastasis and recurrence, which are primarily attributed to the angiogenesis. So, the anti-angiogenesis treatment has become the new approach for HCC therapy. In addition to treating leukemia, arsenic trioxide (As2O3) also suppresses other solid tumors, including HCC. However, the roles of As2O3 in the angiogenesis potential of HCC cells remain unclear. In our present study, As2O3 attenuated the angiogenic ability by the microRNA-491 (miR-491)-mediated inhibition of TGF-β/SMAD3/NF-κB signal pathway in MHCC97H and MHCC97L cells. Briefly, in these cells, As2O3 improved the expression of miR-491 via DNA-demethylation; miR-491, which targeted the SMAD3-3'-UTR, decreased the expression/function of SMAD3, leading to the inactivation of NF-κB/IL-6/STAT-3 signaling; knockdown of miR-491 abolished the As2O3-induced inhibitions of the TGF-β/SMAD3/NF-κB pathway, the VEGF secretion, and the angiogenesis. By understanding a novel mechanism whereby As2O3 inhibits the angiogenic potential in HCC cells, our study would help in the design of future strategies of developing As2O3 as a potential chemopreventive agent when used alone or in combination with other current anticancer drugs.

miRNAs affect the development of hepatocellular carcinoma via dysregulation of their biogenesis and expression

The pathogenesis of hepatocellular carcinoma (HCC) is not fully understood, which has affected the early diagnosis and treatment of HCC and the survival time of patients. MicroRNAs (miRNAs) are a class of evolutionarily conserved small, non-coding RNAs, which regulate the expression of various genes post-transcriptionally. Emerging evidence indicates that the key enzymes involved in the miRNA biosynthesis pathway and some tumor-specific miRNAs are widely deregulated or upregulated in HCC and closely associated with the occurrence and development of various cancers, including HCC. Early studies have shown that miRNAs have critical roles in HCC progression by targeting many critical protein-coding genes, thereby contributing to the promotion of cell proliferation; the avoidance of apoptosis, inducing via angiogenesis; and the activation of invasion and metastasis pathways. Experimental data indicate that discovery of increasing numbers of aberrantly expressed miRNAs has opened up a new field for investigating the molecular mechanism of HCC progression. In this review, we describe the current knowledge about the roles and validated targets of miRNAs in the above pathways that are known to be hallmarks of HCC, and we also describe the influence of genetic variations in miRNA biosynthesis and genes.

Arsenic trioxide attenuates the invasion potential of human liver cancer cells through the demethylation-activated microRNA-491

Hepatocellular carcinoma (HCC) represents the third leading cause of cancer-related mortality worldwide. Current standard practices for treatment of HCC are less than satisfactory because of metastasis and recurrence. In addition to treating acute promyelocytic leukemia (APL), arsenic trioxide (As2O3) also suppresses other solid tumors, such as HCC. However, the effects of As2O3 on the migration/invasion potential of liver cancer cells and the molecular mechanisms underlying in remain unclear. Here we found that As2O3 attenuated the migration/invasion potential of HCC cell lines by blocking matrix metalloproteinases (MMPs) activities and inducing a mesenchymal to epithelial transition (MET). Indeed, As2O3 elevated the expression of microRNA-491 (miR-491) via demethylation. On one hand, as a target miRNA of MMP9, miR-491 decreased the MMP9 expression. On the other hand, miR-491 blocked the activation of nuclear factor κB (NF-κB), which transcriptionally inactivated MMP2 and induced a MET (as determined by the increased expression of E-cadherin and decreased expressions of snail, slug, and vimentin). Knockdown of miR-491 abolished the As2O3-induced MMPs inactivation, MET, and the migration/invasion potential of HCC cell lines. By understanding a novel mechanism how As2O3 inhibits the migration/invasion potential of liver cancer cells, our study may help to identify potential therapeutic targets for liver cancer.

MicroRNAs in the Regulation of MMPs and Metastasis

MicroRNAs are integral molecules in the regulation of numerous physiological cellular processes including cellular differentiation, proliferation, metabolism and apoptosis. Their function transcends normal physiology and extends into several pathological entities including cancer. The matrix metalloproteinases play pivotal roles, not only in tissue remodeling, but also in several physiological and pathological processes, including those supporting cancer progression. Additionally, the contribution of active MMPs in metastatic spread and the establishment of secondary metastasis, via the targeting of several substrates, are also well established. This review focuses on the important miRNAs that have been found to impact cancer progression and metastasis through direct and indirect interactions with the matrix metalloproteinases.

MiR-101 suppresses the epithelial-to-mesenchymal transition by targeting ZEB1 and ZEB2 in ovarian carcinoma

Ovarian carcinoma is the most lethal gynecologic malignancy; the majority of patients succumb to the disease within 5 years of diagnosis. The poor survival rate is attributed to diagnosis at advanced stage, when the tumor has metastasized. The epithelial-to-mesenchymal transition (EMT) is a necessary step toward metastatic tumor progression. Through integrated computational analysis, we recently identified a master microRNA (miRNA) network that includes miR-101 and regulates EMT in ovarian carcinoma. In the present study, we characterized the functions of miR-101. Using reporter gene assays, we demonstrated that miR-101 suppressed the expression of the E-cadherin repressors ZEB1 and ZEB2 by directly targeting the 3'-untranslated region (3'UTR) of both ZEB1 and ZEB2. Introduction of miR-101 significantly inhibited EMT and cell migration and invasion. Introducing cDNAs of ZEB1 and ZEB2 without 3'UTR abrogated miR-101-induced EMT alteration, respectively. Our findings showed that miR-101 represents a redundant mechanism for the miR-200 family that regulates EMT through two major E-cadherin transcriptional repressors.

Post-transcriptional regulatory network of epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions

Epithelial-to-mesenchymal transition (EMT) and its reverse process, mesenchymal-to-epithelial transition (MET), play important roles in embryogenesis, stem cell biology, and cancer progression. EMT can be regulated by many signaling pathways and regulatory transcriptional networks. Furthermore, post-transcriptional regulatory networks regulate EMT; these networks include the long non-coding RNA (lncRNA) and microRNA (miRNA) families. Specifically, the miR-200 family, miR-101, miR-506, and several lncRNAs have been found to regulate EMT. Recent studies have illustrated that several lncRNAs are overexpressed in various cancers and that they can promote tumor metastasis by inducing EMT. MiRNA controls EMT by regulating EMT transcription factors or other EMT regulators, suggesting that lncRNAs and miRNA are novel therapeutic targets for the treatment of cancer. Further efforts have shown that non-coding-mediated EMT regulation is closely associated with epigenetic regulation through promoter methylation (e.g., miR-200 or miR-506) and protein regulation (e.g., SET8 via miR-502). The formation of gene fusions has also been found to promote EMT in prostate cancer. In this review, we discuss the post-transcriptional regulatory network that is involved in EMT and MET and how targeting EMT and MET may provide effective therapeutics for human disease.

Evidence for and against epithelial-to-mesenchymal transition in the liver

The outcome of liver injury is determined by the success of repair. Liver repair involves replacement of damaged liver tissue with healthy liver epithelial cells (including both hepatocytes and cholangiocytes) and reconstruction of normal liver structure and function. Current dogma posits that replication of surviving mature hepatocytes and cholangiocytes drives the regeneration of liver epithelium after injury, whereas failure of liver repair commonly leads to fibrosis, a scarring condition in which hepatic stellate cells, the main liver-resident mesenchymal cells, play the major role. The present review discusses other mechanisms that might be responsible for the regeneration of new liver epithelial cells and outgrowth of matrix-producing mesenchymal cells during hepatic injury. This theory proposes that, during liver injury, some epithelial cells undergo epithelial-to-mesenchymal transition (EMT), acquire myofibroblastic phenotypes/features, and contribute to fibrogenesis, whereas certain mesenchymal cells (namely hepatic stellate cells and stellate cell-derived myofibroblasts) undergo mesenchymal-to-epithelial transition (MET), revert to epithelial cells, and ultimately differentiate into either hepatocytes or cholangiocytes. Although this theory is highly controversial, it suggests that the balance between EMT and MET modulates the outcome of liver injury. This review summarizes recent advances that support or refute the concept that certain types of liver cells are capable of phenotype transition (i.e., EMT and MET) during both culture conditions and chronic liver injury.