Igf2-derived intronic miR-483 promotes mouse hepatocellular carcinoma cell proliferation

MicroRNA-483-5p Inhibits Hepatocellular Carcinoma Cell Proliferation, Cell Steatosis, and Fibrosis by Targeting PPARα and TIMP2

MicroRNAs (miRNAs) are small non-coding RNA molecules that bind with the 3′ untranslated regions (UTRs) of genes to regulate expression. Downregulation of miR-483-5p (miR-483) is associated with the progression of hepatocellular carcinoma (HCC). However, the significant roles of miR-483 in nonalcoholic fatty liver disease (NAFLD), alcoholic fatty liver diseases (AFLD), and HCC remain elusive. In the current study, we investigated the biological significance of miR-483 in NAFLD, AFLD, and HCC in vitro and in vivo. The downregulation of miR-483 expression in HCC patients’ tumor samples was associated with Notch 3 upregulation. Overexpression of miR-483 in a human bipotent progenitor liver cell line HepaRG and HCC cells dysregulated Notch signaling, inhibited cell proliferation/migration, induced apoptosis, and increased sensitivity towards antineoplastic agents sorafenib/regorafenib. Interestingly, the inactivation of miR-483 upregulated cell steatosis and fibrosis signaling by modulation of lipogenic and fibrosis gene expression. Mechanistically, miR-483 targets PPARα and TIMP2 gene expression, which leads to the suppression of cell steatosis and fibrosis. The downregulation of miR-483 was observed in mice liver fed with a high-fat diet (HFD) or a standard Lieber-Decarli liquid diet containing 5% alcohol, leading to increased hepatic steatosis/fibrosis. Our data suggest that miR-483 inhibits cell steatosis and fibrogenic signaling and functions as a tumor suppressor in HCC. Therefore, miR-483 may be a novel therapeutic target for NAFLD/AFLD/HCC management in patients with fatty liver diseases and HCC.

Treadmill training improves cognitive function by increasing IGF2 targeted downregulation of miRNA-483

Optimal exercise can promote the development of cognitive functions. Nevertheless, mechanisms that elicit these positive effects of exercise still need to be elucidated. Insulin-like growth factor 2 (IGF2) is known to act as a potent enhancer of memory and cognitive functions, whereas the mechanism by which IGF2 regulates cognitive functions in terms of moderate treadmill exercise remains largely vague. In the study, rats were subjected to low-, moderate-, and high-intensity treadmill training for 6 weeks. Then, the Morris water maze test was used to investigate spatial learning and memory ability in rats subjected to treadmill exercises of different intensities. Subsequently, gene chip and bioinformatics analyses were used to explore IGF2 and predict target microRNAs (miRNAs). Quantitative real-time polymerase chain reaction, western blot, and immunofluorescence analysis were performed to detect the levels of IGF2. Furthermore, IGF2-small interfering RNA, the miRNA-483-mimic, and the miRNA-483-inhibitor were transfected to determine the role of IGF2 and miRNA-483 in the growth of hippocampal neurons. The results of the Morris water maze test showed that moderate-intensity treadmill training enhanced cognitive functions; meanwhile, the expression of IGF2 was significantly upregulated in the hippocampus after moderate-intensity treadmill exercise. From databases, miRNA-483 was screened and predicted as the target gene of IGF2. Moreover, silencing IGF2 inhibited neurite growth in the hippocampus of rats, the miRNA-483-inhibitor ameliorated silencing IGF2 induced impairment of hippocampal neurons. These findings suggested that treadmill training could enhance cognitive functions, wherein the underlying mechanism involved an increase in the expression of IGF2 and downregulation of miRNA-483.

Exosomal MicroRNAs as Potential Biomarkers of Hepatic Injury and Kidney Disease in Glycogen Storage Disease Type Ia Patients

Glycogen storage disease type Ia (GSDIa) is an inherited metabolic disorder caused by mutations in the enzyme glucose-6-phosphatase-α (G6Pase-α). Affected individuals develop renal and liver complications, including the development of hepatocellular adenoma/carcinoma and kidney failure. The purpose of this study was to identify potential biomarkers of the evolution of the disease in GSDIa patients. To this end, we analyzed the expression of exosomal microRNAs (Exo-miRs) in the plasma exosomes of 45 patients aged 6 to 63 years. Plasma from age-matched normal individuals were used as controls. We found that the altered expression of several Exo-miRs correlates with the pathologic state of the patients and might help to monitor the progression of the disease and the development of late GSDIa-associated complications.

High expression of IGF2-derived intronic miR-483 predicts outcome in hepatoblastoma

BACKGROUND

The role of microRNAs (miRs) as biomarkers to predict outcome in hepatoblastoma (HB), the most common malignant liver tumor in childhood, has still to be determined. Recently, the so-called four-miR signature has been described to efficiently stratify HB patients according to their prognosis.

OBJECTIVE

We examined the recently described four-miR signature for its clinical relevance in an independent validation cohort of HB patients and tried to optimize its predictive value by analyzing four additional miRs involved in HB biology.

METHODS

Expression of eight miR was determined in 29 tumor and 10 normal liver samples by TaqMan assays and association studies and Kaplan-Meier estimators determined their clinical relevance.

RESULTS

Stratifying HB patients by the four-miR signature showed no difference in patients' outcome, which was also reflected by the lack of association with any clinical risk parameter. Adding miR-23b-5p and miR-23b-3p did also not increase its discriminating power. However, the integration of miR-483-5p and miR-483-3p into the four-miR signature could predict patients with poor outcome that were associated with large tumors and vessel invasive growth with high accuracy.

CONCLUSIONS

The expansion of the four-miR signature by miR-483 serves as a useful biomarker to predict outcome of HB patients.

miR-200a targets Gelsolin: A novel mechanism regulating secretion of microvesicles in hepatocellular carcinoma cells

Microvesicle biogenesis is a highly regulated process. Aberrant release of microvesicles from cancer cells have been associated with their invasiveness and prognosis. However, the mechanism of aberrant release remains poorly understood. Herein, we found that hepatocellular carcinoma cells shed more microvesicles than normal hepatocytes and miR-200a were shown to inhibit the release of microvesicles in hepatocellular carcinoma cells. Then, we confirmed that miR-200a might target Gelsolin and change cytoskeleton to regulate microvesicles secretion. Further miR-200a may inhibit the proliferation of adjacent cells by inhibiting the release of microvesicles. Collectively, our findings indicate that miR-200a regulated the microvesicle biogenesis involved in the hepatocellular carcinoma progression.

Metformin inhibits tumor growth by regulating multiple miRNAs in human cholangiocarcinoma

The antidiabetic drug metformin exerts antineoplastic effects in many types of malignancies, however the effect of metformin on cholangiocarcinoma (CCA) still remains unclear. In the present study, we investigated that metformin treatment was closely associated with the clinicopathologic characteristics and improved postoperative survival of CCA patients. Metformin inhibited CCA tumor growth by cell cycle arrest in vitro and in vivo. We explored that the expression of six miRNAs (mir124, 182, 27b, let7b, 221 and 181a), which could directly target cell-cycle-regulatory genes, was altered by metformin in vitro and in vivo. These miRNAs were dysregulated in cholangiocarcinoma and promoted the CCA genesis and metformin exactly modulated these carcinogenic miRNAs expression to arrest the cell cycle and inhibit the proliferation. Meanwhile, these miRNAs expression changes correlated with the tumor volume and postoperative survival of CCA patients and could be used to predict the prognosis. Further we confirmed that metformin upregulated Drosha to modulate these miRNAs expression. Our results elucidated that metformin inhibited CCA tumor growth via the regulation of Drosha-mediated multiple carcinogenic miRNAs expression and comprehensive evaluation of these miRNAs expression could be more efficient to predict the prognosis. Moreover, metformin might be a quite promising strategy for CCA prevention and treatment.

Systematic Review and Meta-Analysis: Circulating miRNAs for Diagnosis of Hepatocellular Carcinoma

Because early-stage hepatocellular carcinoma (HCC) is difficult to diagnose using the existing techniques, identifying better biomarkers would likely improve the patients' prognoses. We performed a systematic review and meta-analysis of published studies to appraise the utility of microRNAs (miRNAs) for the early diagnosis of HCC. Pertinent literature was collected from the Medline, Embase, and Chinese National Knowledge Infrastructure databases. We analyzed 50 studies that included 3423 cases of HCC, 2403 chronic hepatic disease (CH) patients, and 1887 healthy controls in 16 articles. Summary receiver operating characteristic analyses of all miRNAs showed an area under the curve (AUC) of 0.82, with 75.8% sensitivity and 75.0% specificity in discriminating patients with HCC from healthy controls. miR-21 and miR-122 individually distinguished patients with HCC from healthy controls, with an AUC of 0.88 for miR-21 and 0.77 for miR-122. The sensitivity and specificity for miR-21 were 86.6% and 79.5%, respectively, those for miR-122 were 68.0% and 73.3%. We conclude that circulating miRNAs, particularly miR-21, and miR-122, are promising biomarkers for the early diagnosis of HCC.

miR-483-5p and miR-486-5p are down-regulated in cumulus cells of metaphase II oocytes from women with polycystic ovary syndrome

The aim of this study was to compare the expression of microRNAs (miRNAs) in cumulus cells from polycystic ovary syndrome (PCOS) and non-PCOS women. In the present study, miRNA expression profiles of the cumulus cell samples were determined by miRNA microarrays. Quantification of selected miRNAs and predicted target genes was performed using quantitative real-time PCR (qRT-PCR). The results showed that miR-483-5p and miR-486-5p are significantly decreased in cumulus cells of PCOS patients PCOS (fold change >2, false discovery rate <0.001). qRT-PCR found that four predicted genes, SOCS3, SRF, PTEN and FOXO1, were significantly increased in PCOS cumulus cells (all P < 0.001), and IGF2 (host gene of miR-483-5p) was significantly decreased in PCOS cumulus cells (P < 0.001). These results indicated that miR-483-5p might play an important role in reducing insulin resistance, and that miR-486-5p might promote cumulus cell proliferation through activation of PI3K/Akt. The findings from this study provided new insights into the complex molecular mechanisms involved in PCOS by revealing pathways possibly regulated by miRNAs. The differences in miRNAs (miR-483-5p, miR-486-5p) and their target gene expression in cumulus cells may provide clues for future research and help to explain aberrant follicular development and subfertility in women with PCOS.

The GH-IGF-SST system in hepatocellular carcinoma: biological and molecular pathogenetic mechanisms and therapeutic targets

Hepatocellular carcinoma (HCC) is the sixth most common malignancy worldwide. Different signalling pathways have been identified to be implicated in the pathogenesis of HCC; among these, GH, IGF and somatostatin (SST) pathways have emerged as some of the major pathways implicated in the development of HCC. Physiologically, GH-IGF-SST system plays a crucial role in liver growth and development since GH induces IGF1 and IGF2 secretion and the expression of their receptors, involved in hepatocytes cell proliferation, differentiation and metabolism. On the other hand, somatostatin receptors (SSTRs) are exclusively present on the biliary tract. Importantly, the GH-IGF-SST system components have been indicated as regulators of hepatocarcinogenesis. Reduction of GH binding affinity to GH receptor, decreased serum IGF1 and increased serum IGF2 production, overexpression of IGF1 receptor, loss of function of IGF2 receptor and appearance of SSTRs are frequently observed in human HCC. In particular, recently, many studies have evaluated the correlation between increased levels of IGF1 receptors and liver diseases and the oncogenic role of IGF2 and its involvement in angiogenesis, migration and, consequently, in tumour progression. SST directly or indirectly influences tumour growth and development through the inhibition of cell proliferation and secretion and induction of apoptosis, even though SST role in hepatocarcinogenesis is still opened to argument. This review addresses the present evidences suggesting a role of the GH-IGF-SST system in the development and progression of HCC, and describes the therapeutic perspectives, based on the targeting of GH-IGF-SST system, which have been hypothesised and experimented in HCC.

Overexpression of miR-483-5p/3p cooperate to inhibit mouse liver fibrosis by suppressing the TGF-β stimulated HSCs in transgenic mice

The transition from liver fibrosis to hepatocellular carcinoma (HCC) has been suggested to be a continuous and developmental pathological process. MicroRNAs (miRNAs) are recently discovered molecules that regulate the expression of genes involved in liver disease. Many reports demonstrate that miR-483-5p and miR-483-3p, which originate from miR-483, are up-regulated in HCC, and their oncogenic targets have been identified. However, recent studies have suggested that miR-483-5p/3p is partially down-regulated in HCC samples and is down-regulated in rat liver fibrosis. Therefore, the aberrant expression and function of miR-483 in liver fibrosis remains elusive. In this study, we demonstrate that overexpression of miR-483 in vivo inhibits mouse liver fibrosis induced by CCl₄. We demonstrate that miR-483-5p/3p acts together to target two pro-fibrosis factors, platelet-derived growth factor-β and tissue inhibitor of metalloproteinase 2, which suppress the activation of hepatic stellate cells (HSC) LX-2. Our work identifies the pathway that regulates liver fibrosis by inhibiting the activation of HSCs.

The IGF2 intronic miR-483 selectively enhances transcription from IGF2 fetal promoters and enhances tumorigenesis

Insulin-like growth factor 2 (IGF2), a developmentally regulated and maternally imprinted gene, is frequently overexpressed in pediatric cancers. Although loss of imprinting (LOI) at fetal promoters contributes to increased IGF2 in tumors, the magnitude of IGF2 expression suggests the involvement of additional regulatory mechanisms. A microRNA (miRNA) screen of primary Wilms' tumors identified specific overexpression of miR-483-5p, which is embedded within the IGF2 gene. Unexpectedly, the IGF2 mRNA itself is transcriptionally up-regulated by miR-483-5p. A nuclear pool of miR-483-5p binds directly to the 5' untranslated region (UTR) of fetal IGF2 mRNA, enhancing the association of the RNA helicase DHX9 to the IGF2 transcript and promoting IGF2 transcription. Ectopic expression of miR-483-5p in IGF2-dependent sarcoma cells is correlated with increased tumorigenesis in vivo. Together, these observations suggest a functional positive feedback loop of an intronic miRNA on transcription of its host gene.

Increased Intragenic IGF2 Methylation is Associated with Repression of Insulator Activity and Elevated Expression in Serous Ovarian Carcinoma

Overexpression of insulin-like growth factor-II (IGF2) is a prominent characteristic of many epithelial ovarian malignancies. IGF2 imprinting and transcription are regulated in part through DNA methylation, which in turn regulates binding of the insulator protein CTCF within the IGF2/H19 imprint center. We have shown that IGF2 overexpression in ovarian cancer is associated with hypermethylation of CTCF binding sites within the IGF2/H19 imprint center. The aim of this study was to investigate the methylation and binding capacity of a novel putative CTCF binding motif located intragenic to IGF2 and determine how this relates to IGF2 expression. Among 35 primary serous epithelial ovarian cancer specimens, methylation of two CpGs, including one within the core binding motif and another adjacent to this motif, was higher in the 18 cancers with elevated IGF2 expression versus 10 with low expression (average 68.2 versus 38.5%; p < 0.0001). We also found that the CpG site within the CTCF binding motif is hypermethylated in male gametes (>92%; average 93.2%; N = 16). We confirmed binding of CTCF to this region in ovarian cancer cells, as well as the paralog of CTCF, Brother Of the Regulator of Imprinted Sites (BORIS), which is frequently overexpressed in cancers. The unmethylated CTCF binding motif has insulator activity in cells that express CTCF or BORIS, but not in cells that express both CTCF and BORIS. These intragenic CpG dinucleotides therefore comprise a novel paternal germline imprint mark and are located in a binding motif for the insulator protein CTCF. Methylation of the CpG dinucleotides is positively correlated with IGF2 transcription, indicating that increased methylation represses insulator function. These combined results suggest that methylation and CTCF binding at this region play important roles in regulating the level of IGF2 transcription. Our data have revealed a novel epigenetic regulatory element within the IGF2/H19 imprinted domain that is highly relevant to aberrant IGF2 expression in ovarian malignancies.

Molecular findings in Beckwith-Wiedemann syndrome

Our understanding of Beckwith-Wiedemann syndrome (BWS) has recently been enhanced by advances in its molecular characterization. These advances have further delineated intricate (epi)genetic regulation of the imprinted gene cluster on chromosome 11p15.5 and the role of these genes in normal growth and development. Studies of the molecular changes associated with the BWS phenotype have been instrumental in elucidating critical molecular elements in this imprinted region. This review will provide updated information on the multiple new regulatory elements that have been recently found to contribute to in cis or in trans control of imprinted gene expression in the chromosome 11p15.5 region and the clinical expression of the BWS phenotype.

Enemy or partner: relationship between intronic micrornas and their host genes

In the past several years, microRNAs have been identified as a class of important regulators of gene expression. One hot topic in the microRNA field is the location of microRNA genes. Most microRNAs are called intronic microRNAs, which are encoded in the introns of coding or non-coding genes. Some research studies have shown that intronic miRNAs coexpress and act similarly to their host genes; however, other research studies have suggested that their level of expression and function are opposite to that of their host genes. Intronic microRNAs have been reported to play an antagonistic or synergetic role as an enemy or a partner of their host genes. Elucidation of the relationship between intronic microRNAs and their host genes will facilitate a deeper understanding of gene expression and the function of introns. This mini review will discuss recent research addressing intronic microRNAs and their host genes.

Drug resistance-related microRNAs in esophageal cancer

INTRODUCTION

Drug resistance has been the main obstacle in cancer therapy. A number of drug resistance-related molecules are under investigation but no one agent has already been used in clinical practice. The research on drug resistance-related microRNAs (miRNAs) may eventually lead to improved clinical strategies and outcomes for patients with esophageal cancer (EC).

AREAS COVERED

This review summarizes the recent advances in drug resistance-related miRNAs in EC, and also analyzes the clinical and therapeutic applications they provide. The authors envisage future developments in the molecular mechanisms of these miRNAs and their potential applications to cancer treatment.

EXPERT OPINION

Drug resistance-related miRNAs can be used as a useful therapeutic tool for EC. More investigations should be performed to promote the success of therapeutic-clinical use of miRNAs in cancer.