Sequential analysis of multistage hepatocarcinogenesis reveals that miR-100 and PLK1 dysregulation is an early event maintained along tumor progression

Increased hsa-miR-100-5p Expression Improves Hepatocellular Carcinoma Prognosis in the Asian Population with PLK1 Variant rs27770A>G

Hepatocellular carcinoma (HCC) has the highest incidence and mortality in the Asian population, and race is an independent risk factor affecting survival time in liver cancer. Micro RNAs (miRNAs) are remarkably dysregulated in HCC and closely associated with HCC prognosis. Recent studies show that genetic variability between ethnic groups may result in differences in the specificity of HCC miRNA biomarkers. Here, we reveal a high expression level of hsa-miR-100-5p, an HCC prognosis-related miRNA, which improves HCC prognosis in the Asian Population with Polo-like kinase 1 (PLK1) variant rs27770A>G. In this study, we discovered that hsa-miR-100-5p was downregulated in various HCC cell lines. While mimics transient transfection and mouse liver cancer model confirmed the interaction between hsa-miR-100-5p and PLK1, a stratified analysis based on the Cancer Genome Atlas Liver Hepatocellular Carcinoma (TCGA-LIHC) data suggest both low hsa-miR-100-5p expression level and high PLK1 expression level associated with poor HCC prognosis, especially in the Asian population. According to the 1000 Genomes Project database, the SNP rs27770 located in 3'UTR of PLK1 had a significantly higher G allele frequency in the East Asian population. Bioinformatics analysis suggested that rs27770 A>G affects PLK1 mRNA secondary structure and alters the hsa-miR-100-5p/PLK1 interaction by forming an additional seedless binding site. This racial variation caused PLK1 to be more vulnerable to hsa-miR-100-5p inhibition, resulting in hsa-miR-100-5p being more favorable for HCC prognosis in the Asian population.

Comprehensive Analysis of Necroptosis-Related Genes as Prognostic Factors and Immunological Biomarkers in Breast Cancer

Breast cancer (BC) is a lethal malignancy with a poor prognosis. Necroptosis is critical in the progression of cancer. However, the expression of genes involved in necroptosis in BC and their association with prognosis remain unclear. We investigated the predictive potential of necroptosis-related genes in BC samples from the TCGA dataset. We used LASSO regression to build a risk model consisting of twelve necroptosis-related genes in BC. Using the necroptosis-related risk model, we were able to successfully classify BC patients into high- and low-risk groups with significant prognostic differences (p = 4.872 × 10 ^-7). Additionally, we developed a matched nomogram predicting 5, 7, and 10-year overall survival in BC patients based on this necroptosis-related risk model. Our next step was to perform multiple GSEA analyses to explore the biological pathways through which these necroptosis-related risk genes influence cancer progression. For these twelve risk model genes, we analyzed CNV, SNV, OS, methylation, immune cell infiltration, and drug sensitivity in pan-cancer. In addition, immunohistochemical data from the THPA database were used to validate the protein expression of these risk model genes in BC. Taken together, we believe that necroptosis-related genes are considered potential therapeutic targets in BC and should be further investigated.

Construction of a ceRNA Network and Comprehensive Analysis of lncRNA in Hepatocellular Carcinoma

To explore the RNA biomolecular marker associated with hepatocellular carcinoma (HCC) prognosis, we constructed a regulatory network of competitive endogenous RNAs (ceRNAs), which provides favorable conditions for the early diagnosis, prognostic monitoring, and personalized treatment of HCC. In this study, the differentially expressed genes (DEGs) of patients with HCC were obtained from the Gene Expression Omnibus. We identified 574 upregulated genes and 274 downregulated genes relevant to HCC occurrence (p < 0.05). Subsequently, we constructed the protein−protein interaction (PPI) network using these DEGs and identified the hub genes from the PPI. We then determined the expression and prognostic values of the hub genes from the GEPIA and Kaplan−Meier plotter databases. After the upstream microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) were respectively identified by miRTarBase and miRNet, we validated the expression of the key miRNAs in the serum using qPCR experiments. Moreover, we identified a two-lncRNA (LINC01184 and ADORA2A-AS1) signature from the upstream lncRNA that effectively predicted overall survival and had promotive effects for HCC. To verify the clinical significance of the signature, we validated the expression of the lncRNA in HCC tissues. Finally, we discovered and identified four mRNAs, four miRNAs, and five lncRNAs associated with the prognosis of HCC and constructed a new ceRNA regulatory network, which will be beneficial for the accurate diagnosis and treatment of HCC.

CircCASC15-miR-100-mTOR may influence the cervical cancer radioresistance

Background

Cervical cancer has ranked the top one in gynecological malignancies for incidence. Radioresistance is now becoming a leading reason of recurrence.

Methods

Our microRNA array data indicated that the miRNA-100 level decreased significantly during radioresistance. In this study, we up-regulated miR-100 in Hela and Siha cells by using miR-100 mimics and observed proliferation and invasion.

Results

It turned out that with overexpression of miR-100, the cells had less invasiveness as well as proliferation. It may target gene mTOR, and it deed reduced EMT. To examine the role of miR-100 in radioresistance, there was no significant result showed by BSP. While the circCASC15 has been identified with sponge function according to RNA pull down and ISH.

Conclusion

The conclusions indicate miR-100 is a tumor suppressor gene and could be a therapeutic target in radio-resistant cervical cancers.

MicroRNAs as Diagnostic Tools in Hepatocellular Carcinoma

Liver cancer is the fourth leading cause of cancer-related deaths worldwide, with hepatocellular carcinoma (HCC) accounting for approximately 80% of all liver cancers. The serum concentration of alpha-fetoprotein (AFP) is the only validated biomarker for HCC diagnosis. MicroRNAs (miRNAs) are small non-coding RNAs of 21–30 nucleotides playing a critical role in human carcinogenesis, with types of miRNAs with oncogenic (oncomiRs) or tumor suppressor features. The altered expression of miRNAs in HCC is associated with many pathological processes, such as cancer initiation, tumor growth, apoptosis escape, promotion of migration and invasion. Moreover, circulating miRNAs have been increasingly investigated as non-invasive biomarkers for HCC diagnosis. MiRNAs’ expression patterns are altered in HCC and several single miRNAs or miRNAs panels have been found significantly up or downregulated in HCC with respect to healthy controls or non-oncological patients (cirrhotic or with viral hepatitis). However, any of the investigated miRNAs or miRNAs panels has entered clinical practice so far. This has mostly to do with lack of protocols standardization, small sample size and discrepancies in the measurement techniques. This review summarizes the major findings regarding the diagnostic role of miRNAs in HCC and their possible use together with standard biomarkers in order to obtain an early diagnosis and easier differential diagnosis from non-cancerous liver disease.

miR-100 Suppresses the Proliferation, Invasion, and Migration of Hepatocellular Carcinoma Cells via Targeting CXCR7

This study is to elucidate the functions of miR-100 in hepatocellular carcinoma progression and to explore the underlying mechanisms. Expression levels of miR-100 in normal-cancer hepatocellular carcinoma tissues were measured using quantitative real-time PCR (qRT-PCR). The invasive and proliferative abilities of hepatocellular carcinoma cell lines transfected with mimic-NC or mimic-miR-100 were measured using transwell, CCK-8, and colony formation assays. The binding sites between CXCR7 and miR-100 were determined using luciferase reporter assays. The correlation of CXCR7 and miR-100 in hepatocellular carcinoma progression was further confirmed by cotransfection assays. Our results showed that miR-100 was significantly lower expressed in hepatocellular carcinoma tissues and negatively associated with CXCR7 expression. Cell functional assays' results found that upregulation of miR-100 inhibited the proliferative, invasive, and migrative abilities in hepatocellular carcinoma cells. Luciferase reporter assay suggested that CXCR7 mRNA and miR-100 bound one another. Increasing CXCR7 expression reversed the inhibitive effects of upregulated miR-100 in hepatocellular carcinoma cells. Further study showed that miR-100/CXCR7 played a role in hepatocellular carcinoma progression by regulating metalloproteinase-2 (MMP2) and vascular endothelial growth factor (VEGF). Conclusively, miR-100 exerts antitumor effects on hepatocellular carcinoma. Overexpression of miR-100 attenuates the invasive and proliferative abilities of hepatocellular carcinoma cells by targeting CXCR7.

Circulating microRNA signatures that predict liver fibrosis progression in patients with HIV-1/hepatitis C virus coinfections

OBJECTIVE

The lack of available biomarkers for diagnosing and predicting different stages of liver disease with a noninvasive strategy is currently one of the main challenges that clinicians are facing. Recent evidence indicates that the plasma levels of specific microRNAs (miRNAs) may be significantly altered in patients with liver injury, including those with HIV type 1 (HIV-1) infections.

DESIGN/METHODS

Large-scale deep sequencing analysis of small RNA expression was performed on plasma samples from 46 patients with HIV-1/hepatitis C virus (HCV) coinfections that did not exhibit liver fibrosis at the time of sampling.

RESULTS

A total of 1065 different miRNAs were identified. After a mean of 10.3 years, 26 out of the 46 patients developed liver fibrosis (stage F2-4) and 20 remained without signs of liver fibrosis (stage F0-1). We identified a signature of seven miRNAs: 100-5p, 192-5p, 99a-5p, 122-5p, 125b-2-3p, 1246 and 194-5p, which were highly correlated with progression to liver fibrosis. These seven miRNAs detected liver fibrosis progression with an area under the curve (AUC) of 0.910-0.806. Two miRNAs, 100-5p and 192-5p, which displayed the best AUC values, yielded a sensitivity of 88% and a specificity of 85% for detecting liver fibrosis progression.

CONCLUSION

Our results demonstrated that circulating miRNA levels had potential in predicting liver fibrosis progression before the clinical detection of liver fibrosis or significant clinical signs, such as elevated liver transaminases or platelets. Thus, our results might facilitate predictions of liver injury progression in patients with HIV-1-infections.

MicroRNAs in the Pathogenesis of Hepatocellular Carcinoma: A Review

Simple Summary

Hepatocellular carcinoma (HCC) is one of the most frequently occurring cancers, and the prognosis for late-stage HCC remains poor. A better understanding of the pathogenesis of HCC is expected to improve outcomes. MicroRNAs (miRNAs) are small, noncoding, single-stranded RNAs that regulate the expression of various target genes, including those in cancer-associated genomic regions or fragile sites in various human cancers. We summarize the central roles of miRNAs in the pathogenesis of HCC and discuss their potential utility as valuable biomarkers and new therapeutic agents for HCC.

Abstract

Hepatocellular carcinoma (HCC) is the seventh most frequent cancer and the fourth leading cause of cancer mortality worldwide. Despite substantial advances in therapeutic strategies, the prognosis of late-stage HCC remains dismal because of the high recurrence rate. A better understanding of the etiology of HCC is therefore necessary to improve outcomes. MicroRNAs (miRNAs) are small, endogenous, noncoding, single-stranded RNAs that modulate the expression of their target genes at the posttranscriptional and translational levels. Aberrant expression of miRNAs has frequently been detected in cancer-associated genomic regions or fragile sites in various human cancers and has been observed in both HCC cells and tissues. The precise patterns of aberrant miRNA expression differ depending on disease etiology, including various causes of hepatocarcinogenesis, such as viral hepatitis, alcoholic liver disease, or nonalcoholic steatohepatitis. However, little is known about the underlying mechanisms and the association of miRNAs with the pathogenesis of HCC of various etiologies. In the present review, we summarize the key mechanisms of miRNAs in the pathogenesis of HCC and emphasize their potential utility as valuable diagnostic and prognostic biomarkers, as well as innovative therapeutic targets, in HCC diagnosis and treatment.

Bioinformatics analysis of key genes in triple negative breast cancer and validation of oncogene PLK1

Background

Breast cancer is the most common malignancy in women. Triple-negative breast cancer (TNBC) refers to a special subtype that is deficient in the expression of estrogen (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER-2). In this study, a variety of bioinformatics analysis tools were used to screen Hub genes related to the occurrence and development of triple negative breast cancer, and their biological functions were analyzed.

Methods

Gene Expression Omnibus (GEO) breast cancer microarray data GSE62931 was selected as the research object. The differentially expressed genes (DEGs) were screened and the protein-protein interaction (PPI) network of DEGs was constructed using bioinformatics tools. The Hub genes were also screened. The Gene Ontology (GO) knowledgebase and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used for biological enrichment analysis. The Gene Expression Profiling Interactive Analysis (GEPIA) online tool was used to verify the expression of the screened genes and patient survival. The effects of polo-like kinase 1 (PLK1) on the proliferation, invasion, migration, and dryness of breast cancer cells were verified using cell counting kit 8 (CCK-8), transwell migration assays, scratch tests, and clone formation tests. An animal model of subcutaneous xenotransplantation of breast cancer was established to evaluate the effect of PLK1 on the proliferation of breast cancer.

Results

A total of 824 DEGs were screened by GSE62931 microarray data; 405 of which were up-regulated and 419 of which were down-regulated. Functional enrichment analysis showed that these DEGs were mainly enriched in cancer-related pathways and were primarily involved in biological processes (BP) such as cell and mitotic division. From the Hub gene screening, PLK1 was further identified as the Hub gene associated with TNBC. Cell and animal experiments indicated that PLK1 promotes the proliferation, invasion, migration, and clone formation of breast cancer cells.

Conclusions

Gene chip combined with bioinformatics methods can effectively analyze the DEGs related to the occurrence and development of breast cancer, and the screening of PLK1 can provide theoretical guidance for further research on the molecular mechanism of breast cancer and the screening of molecular markers.

HIF1A activates the transcription of lncRNA RAET1K to modulate hypoxia-induced glycolysis in hepatocellular carcinoma cells via miR-100-5p

Hepatocellular carcinoma (HCC) remains the primary cause of cancer-related death. Metabolic change is the major characteristic of cancer. The present study attempted to investigate the regulatory mechanisms of HCC energy metabolism from the perspective of noncoding RNA regulation of HIF1A and LDHA. The expression of miR-100-5p expression was significantly suppressed in HCC tissue samples and HCC cell lines under 1% O₂-induced hypoxia. miR-100-5p overexpression significantly suppressed hypoxia-induced increases in lactate concentration and glucose uptake. Exposure to 1% O₂ induced HIF1A protein and reduced miR-100-5p expression, while HIF1A silencing dramatically rescued miR-100-5p expression upon 1% O₂ exposure. In addition, 1% O₂-induced increases in lactate concentration and glucose uptake were also suppressed by HIF1A silencing. Next, by analyzing available data in TCGA, we found that lncRNA RAET1K was correlated with HIF1A and miR-100-5p.LncRNA RAET1K could downregulate the expression of miR-100-5p by acting as a sponge, while HIF1A bound the lncRNA RAET1K promoter region to activate its transcription. LncRNA RAET1K silencing significantly suppressed HCC cell proliferation and invasion and also suppressed hypoxia-induced increases in lactate concentration and glucose uptake, while miR-100-5p inhibition reversed the effects of lncRNA RAET1K silencing on hypoxia-induced glycolysis in HCC cells. Finally, the expression of HIF1A, lncRNA RAET1K, and LDHA was upregulated in HCC tissue specimens; the expression of miR-100-5p was negatively related to HIF1A, lncRNA RAET1K, and LDHA; and HIF1A, lncRNA RAET1K, and LDHA were positively correlated with each other. In conclusion, the HIF1A/lncRNA RAET1K/miR-100-5p axis modulates hypoxia-induced glycolysis in HCC cells and might affect HCC progression.

MicroRNAs in Animal Models of HCC

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality. Molecular heterogeneity and absence of biomarkers for patient allocation to the best therapeutic option contribute to poor prognosis of advanced stages. Aberrant microRNA (miRNA) expression is associated with HCC development and progression and influences drug resistance. Therefore, miRNAs have been assayed as putative biomarkers and therapeutic targets. miRNA-based therapeutic approaches demonstrated safety profiles and antitumor efficacy in HCC animal models; nevertheless, caution should be used when transferring preclinical findings to the clinics, due to possible molecular inconsistency between animal models and the heterogeneous pattern of the human disease. In this context, models with defined genetic and molecular backgrounds might help to identify novel therapeutic options for specific HCC subgroups. In this review, we describe rodent models of HCC, emphasizing their representativeness with the human pathology and their usefulness as preclinical tools for assessing miRNA-based therapeutic strategies.

Prognostic value and prospective molecular mechanism of miR-100-5p in hepatocellular carcinoma: A comprehensive study based on 1,258 samples

The prognostic value and molecular mechanism of microRNA-100-5p (miR-100-5p) in hepatocellular carcinoma (HCC) are still unclear. To explore the prognostic value and the mechanism of miR-100-5p in HCC, the present study analyzed the results of 18 previous studies and bioinformatic datasets. The clinical significance of miR-100-5p and its targets in HCC were investigated using The Cancer Genome Atlas and the Gene Expression Omnibus, as well as relevant literature. In total, 12 online tools were used to predict the target genes of miR-100-5p. Bioinformatics analysis and Spearman correlation analysis were performed, and genomic alterations of the hub genes were evaluated. A meta-analysis with 1,258 samples revealed that miR-100-5p was significantly downregulated in HCC [standard mean difference (SMD), −0.94; 95% confidence interval (CI), −1.14 to −0.74; I², 35.2%]. Lower miR-100-5p expression was associated with poorer clinical characteristics and a poorer prognosis for patients with HCC. Additionally, bioinformatics analysis revealed that the ‘regulation of transcription’, ‘chromatin remodeling complex’, ‘transcription regulator activity’, ‘pathways in cancer’ and ‘heparan sulfate biosynthesis’ were the most enriched terms. Furthermore, expression of histone deacetylase (HDAC)2, HDAC3, SHC-transforming protein 1 (SHC1), Ras-related protein Rac1 (RAC1) and E3 ubiquitin-protein ligase CBL (CBL) was negatively correlated with miR-100-5p expression. Among these, upregulated HDAC2 [hazard ratio (HR), 1.910; 95% CI, 1.309–2.787; P=0.0007], HDAC3 (HR, 1.474; 95% CI, 1.012–2.146; P=0.0435), SHC1 (HR, 1.52; 95% CI, 1.043–2.215; P=0.0281) and RAC1 (HR, 1.817; 95% CI, 1.248–2.645; P=0.0022) were associated with shorter survival. Alterations in HDAC2, SHC1, RAC1 and IGF1R were linked with a poorer outcome for HCC, and alternative splicing of SHC and RAC1 were significantly decreased and increased in HCC, respectively. In summary, the downregulation of miR-100-5p may be involved in the progression and prognosis of HCC. The upregulation of HDAC2, HDAC3, SHC1 and RAC1 may indicate a poorer survival rate for patients with HCC. Thus, miR-100-5p and these 4 potential target genes may provide novel therapeutic targets and prognostic predictors for patients with HCC.

Integrative analysis reveals disrupted pathways regulated by microRNAs in cancer

MicroRNAs (miRNAs) are small endogenous regulatory molecules that modulate gene expression post-transcriptionally. Although differential expression of miRNAs have been implicated in many diseases (including cancers), the underlying mechanisms of action remain unclear. Because each miRNA can target multiple genes, miRNAs may potentially have functional implications for the overall behavior of entire pathways. Here, we investigate the functional consequences of miRNA dysregulation through an integrative analysis of miRNA and mRNA expression data using a novel approach that incorporates pathway information a priori. By searching for miRNA-pathway associations that differ between healthy and tumor tissue, we identify specific relationships at the systems level which are disrupted in cancer. Our approach is motivated by the hypothesis that if an miRNA and pathway are associated, then the expression of the miRNA and the collective behavior of the genes in a pathway will be correlated. As such, we first obtain an expression-based summary of pathway activity using Isomap, a dimension reduction method which can articulate non-linear structure in high-dimensional data. We then search for miRNAs that exhibit differential correlations with the pathway summary between phenotypes as a means of finding aberrant miRNA-pathway coregulation in tumors. We apply our method to cancer data using gene and miRNA expression datasets from The Cancer Genome Atlas and compare ∼10⁵ miRNA-pathway relationships between healthy and tumor samples from four tissues (breast, prostate, lung and liver). Many of the flagged pairs we identify have a biological basis for disruption in cancer.

regQTLs: Single nucleotide polymorphisms that modulate microRNA regulation of gene expression in tumors

Genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with trait diversity and disease susceptibility, yet their functional properties often remain unclear. It has been hypothesized that SNPs in microRNA binding sites may disrupt gene regulation by microRNAs (miRNAs), short non-coding RNAs that bind to mRNA and downregulate the target gene. While several studies have predicted the location of SNPs in miRNA binding sites, to date there has been no comprehensive analysis of their impact on miRNA regulation. Here we investigate the functional properties of genetic variants and their effects on miRNA regulation of gene expression in cancer. Our analysis is motivated by the hypothesis that distinct alleles may cause differential binding (from miRNAs to mRNAs or from transcription factors to DNA) and change the expression of genes. We previously identified pathways—systems of genes conferring specific cell functions—that are dysregulated by miRNAs in cancer, by comparing miRNA–pathway associations between healthy and tumor tissue. We draw on these results as a starting point to assess whether SNPs on dysregulated pathways are responsible for miRNA dysregulation of individual genes in tumors. Using an integrative regression analysis that incorporates miRNA expression, mRNA expression, and SNP genotype data, we identify functional SNPs that we term “regulatory QTLs (regQTLs)”: loci whose alleles impact the regulation of genes by miRNAs. We apply the method to breast, liver, lung, and prostate cancer data from The Cancer Genome Atlas, and provide a tool to explore the findings.

Genomics studies have identified single nucleotide polymorphisms (SNPs) associated with trait diversity and disease susceptibility, yet the mechanism of action of many genetic variants remains unclear. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules that base-pair coding mRNAs to regulate gene transcription. We hypothesize that SNP variants may affect the ability of miRNAs to bind their target genes, thus influencing gene regulation. To identify these “regulatory QTLs” (regQTLs), we integrate miRNA expression, mRNA expression, and SNP data to identify miRNAs that are associated with pathway dysregulation in tumors, and assess whether SNPs on these pathways are responsible for disrupted miRNA-gene regulation. This data-driven approach enables the discovery of SNPs whose alleles impact gene regulation by miRNAs, with functional consequences for tumor biology. We detail the method, apply it to data from The Cancer Genome Atlas, and provide a tool to explore the findings.

MIR100 host gene-encoded lncRNAs regulate cell cycle by modulating the interaction between HuR and its target mRNAs

Long non-coding RNAs (lncRNAs) regulate vital biological processes, including cell proliferation, differentiation and development. A subclass of lncRNAs is synthesized from microRNA (miRNA) host genes (MIRHGs) due to pre-miRNA processing, and are categorized as miRNA-host gene lncRNAs (lnc-miRHGs). Presently, the cellular function of most lnc-miRHGs is not well understood. We demonstrate a miRNA-independent role for a nuclear-enriched lnc-miRHG in cell cycle progression. MIR100HG produces spliced and stable lncRNAs that display elevated levels during the G1 phase of the cell cycle. Depletion of MIR100HG-encoded lncRNAs in human cells results in aberrant cell cycle progression without altering the levels of miRNA encoded within MIR100HG. Notably, MIR100HG interacts with HuR/ELAVL1 as well as with several HuR-target mRNAs. Further, MIR100HG-depleted cells show reduced interaction between HuR and three of its target mRNAs, indicating that MIR100HG facilitates interaction between HuR and target mRNAs. Our studies have unearthed novel roles played by a MIRHG-encoded lncRNA in regulating RNA binding protein activity, thereby underscoring the importance of determining the function of several hundreds of lnc-miRHGs that are present in human genome.

Hsa-let-7b inhibits cell proliferation by targeting PLK1 in HCC

Previous studies have shown that high levels of PLK1 are expressed in HCC, and PLK1 inhibitors are being tested in clinical trials. However, the mechanisms, which regulate PLK1 expression in HCC, have not been clarified. Here, we show that induction of let-7b over-expression inhibits the PLK1-regulated luciferase activity in HEK-293T cells, and decreases the levels of PLK1 expression in HCC cells. Furthermore, the levels of let-7b expression were negatively correlated with PLK1 expression in HCC tissues. Let-7b over-expression inhibited the proliferation of HCC cells and promoted their apoptosis, which were partially rescued by increased PLK1 expression. Let-7b over-expression decreased the levels of PLK1, CDC25C and Survivin phosphorylation and CDC2, β-catenin, TCF-4 expression, which were mitigated by increased PLK1 expression in MHCC-97H cells. Let-7b over-expression inhibited the development and growth of implanted HCC tumors in mice by decreasing PLK1 and Survivin expression in the tumors. Together, our data indicated that let-7b targeted PLK1 to inhibit HCC growth and induce their apoptosis by attenuating the PLK1-mediated Survivin phosphorylation. Our findings may provide new insights into the pathogenesis of HCC.

Effects of PLK1 on proliferation, invasion and metastasis of gastric cancer cells through epithelial-mesenchymal transition

Effects of polo-like kinase (PLK1) on proliferation, migration and invasion capacities of gastric cancer cells through epithelial-mesenchymal transition (EMT) were investigated. Small-interfering ribonucleic acid (siRNA) with targeted interference in PLK1 gene was designed and transfected into gastric cancer MGC-803 cells via Lipofectamine to inhibit the expression of PLK1 gene in MGC-803 cells. The proliferation of MGC-803 cells was detected via methyl thiazolyl tetrazolium (MTT) assay. The mRNA and protein expression of PLK1 and EMT-related marker (E-cadherin) was detected via real-time polymerase chain reaction and western blot analysis, respectively. The effects of interference in PLK1 gene on migration and invasion of MGC-803 cells were studied via wound healing assay and Transwell chamber assay, respectively. Results of MTT assay showed that compared with that in control group, the cell proliferation in PLK1 siRNA group was significantly inhibited (p<0.01). Compared with those in control group, the mRNA and protein expression of PLK1 in PLK1 siRNA group was significantly decreased (p<0.01), but the mRNA and protein expression of E-cadherin was obviously upregulated (p<0.01). Results of wound healing assay and invasion assay showed that the capacity of migration and invasion of MGC-803 cells in PLK1 siRNA group was significantly inhibited compared with those in control group (p<0.01). In conclusion, PLK1 enhances the proliferation, migration and invasion of gastric cancer MGC-803 cells through affecting EMT.

MicroRNA miR-509 Regulates ERK1/2, the Vimentin Network, and Focal Adhesions by Targeting Plk1

Polo-like kinase 1 (Plk1) has been implicated in mitosis, cytokinesis, and proliferation. The mechanisms that regulate Plk1 expression remain to be elucidated. It is reported that miR-100 targets Plk1 in certain cancer cells. Here, treatment with miR-100 did not affect Plk1 protein expression in human airway smooth muscle cells. In contrast, treatment with miR-509 inhibited the expression of Plk1 in airway smooth muscle cells. Exposure to miR-509 inhibitor enhanced Plk1 expression in cells. Introduction of miR-509 reduced luciferase activity of a Plk1 3'UTR reporter. Mutation of miR-509 targeting sequence in Plk1 3'UTR resisted the reduction of the luciferase activity. Furthermore, miR-509 inhibited the PDGF-induced phosphorylation of MEK1/2 and ERK1/2, and cell proliferation without affecting the expression of c-Abl, a tyrosine kinase implicated in cell proliferation. Moreover, we unexpectedly found that vimentin filaments contacted paxillin-positive focal adhesions. miR-509 exposure inhibited vimentin phosphorylation at Ser-56, vimentin network reorganization, focal adhesion formation, and cell migration. The effects of miR-509 on ERK1/2 and vimentin were diminished in RNAi-resistant Plk1 expressing cells treated with miR-509. Taken together, these findings unveil previously unknown mechanisms that miR-509 regulates ERK1/2 and proliferation by targeting Plk1. miR-509 controls vimentin cytoskeleton reorganization, focal adhesion assembly, and cell migration through Plk1.

Large-scale screening of circulating microRNAs in individuals with HIV-1 mono-infections reveals specific liver damage signatures

Human immunodeficiency virus type 1 (HIV-1)-induced inflammation and/or long-term antiretroviral drug toxicity may contribute to the evolution of liver disease. We investigated circulating plasma microRNAs (miRNAs) as potential biomarkers of liver injury in patients mono-infected with HIV-1. We performed large-scale deep sequencing analyses of small RNA level on plasma samples from patients with HIV-1 mono-infection that had elevated or normal levels of alanine aminotransferase (ALT) or focal nodular hyperplasia (FNH). Hepatitis C virus (HCV) mono-infected patients were also studied. Compared to healthy donors, patients with HIV-1 or HCV mono-infections showed significantly altered (fold change >2, adjusted p < 0.05) level of 25 and 70 miRNAs, respectively. Of the 25 altered miRNAs found in patients with HIV-1, 19 were also found in patients mono-infected with HCV. Moreover, 13 of the 14 most up-regulated miRNAs (range: 9.3-3.4-fold increase) in patients with HCV mono-infections were also up-regulated in patients with HIV-1 mono-infections. Importantly, most of these miRNAs significantly and positively correlated with ALT and aspartate aminotransferase (AST) levels, and liver fibrosis stage (p < 0.05). MiR-122-3p and miR-193b-5p were highly up-regulated HIV-1 mono-infected patients with elevated ALT or FNH, but not in HIV-1 patients with normal levels of ALT. These results reveal that HIV-1 infections impacted liver-related miRNA levels in the absence of an HCV co-infection, which highlights the potential of miRNAs as biomarkers for the progression of liver injury in HIV-1 infected patients.

Combined effects of PLK1 and RAS in hepatocellular carcinoma reveal rigosertib as promising novel therapeutic "dual-hit" option

Inhibition of RAS-RAF-ERK-signaling is a major mechanism mediated by the multi-kinase inhibitors sorafenib and regorafenib, the only effective therapeutic approaches for advanced hepatocellular carcinoma (HCC). This underlines the importance of RAS-RAF-ERK-signaling in HCC. Most RAS isoforms were not yet described to play crucial roles in HCC. However, several studies indicate that the HRAS isoform can function as potent oncogene in HCC, but pharmacologic RAS inhibition has not yet been investigated. Moreover, the cell cycle promoting polo-like kinase 1 (PLK1) is an increasingly recognized therapeutic target in HCC that can be activated by RAS-RAF-signaling. A recently developed small molecule inhibitor, ON-01910 ("rigosertib", RGS), was shown to interfere with both RAS- and PLK1-signaling. The aim of this study was to analyze the effects of RGS in HCC and to assess PLK1 and HRAS expression in HCC. RGS treatment reduced cell proliferation and induced cell cycle arrest in human HCC cell lines in vitro. Moreover, RGS strongly inhibited both ERK- and AKT-activation in HCC cells, indicating disruption of RAS-signaling. Analysis of HCC patient data showed that PLK1 and HRAS expression levels are upregulated during HCC development and in advanced HCC, respectively. High expression levels of PLK1 significantly correlated with poor patient survival. Moreover, high expression of both PLK1 and HRAS revealed combined effects on patient outcome. This underscores the importance of these genes and associated pathways in HCC. We newly demonstrate the therapeutic potential of RGS in HCC by inhibition of both PLK1 activation and major RAS-pathways, revealing a novel therapeutic "dual-hit" approach for HCC.

Regulation of PLK1 through competition between hnRNPK, miR-149-3p and miR-193b-5p

Polo-like kinase 1 (PLK1) is a critical regulator of cell cycle progression and apoptosis. However, its regulation remains poorly understood. In the present study, we investigated the molecular mechanism underlying the post-transcriptional regulation of PLK1. We observed that heterogeneous nuclear ribonucleoprotein K (hnRNPK) and PLK1 were positively associated in several different cancers and high expression levels of them correlated with poor prognosis in patients with cancer. Knockdown of hnRNPK resulted in reduced expression of PLK1, whereas conversely, PLK1 expression was increased in hnRNPK-overexpressing cells. We found that hnRNPK regulated PLK1 expression through KH1- and KH2-dependent interactions with the 3'UTR of PLK1 mRNA. In addition, microRNA-149-3p (miR-149-3p) and miR-193b-5p suppressed PLK1 expression by targeting the 3'UTR of PLK1 mRNA. MicroRNA-elicited enrichment of PLK1 mRNA in Ago2 immunoprecipitation was altered by the presence or absence of hnRNPK. Furthermore, the deletion of the cytosine (C)-rich sequences of the 3'UTR of PLK1 mRNA abolished the decreased PLK1 expression observed via hnRNPK silencing and administration of miRNAs, a finding that suggests that hnRNPK shares this C-rich motif with miR-149-3p and miR-193b-5p. We also found that downregulation of PLK1 by either silencing hnRNPK or overexpression of miR-149-3p and miR-193b-5p decreased clonogenicity and induced apoptosis. Our findings from this study demonstrate that hnRNPK regulates PLK1 expression by competing with the PLK1-targeting miRNAs, miR-149-3p and miR-193b-5p.

Altered miRNA expression in aniline-mediated cell cycle progression in rat spleen

Aniline exposure is associated with toxicity to the spleen, however, early molecular events in aniline-induced cell cycle progression in the spleen remain unknown. MicroRNAs (miRNAs) have been implicated in tumor development by modulating key cell cycle regulators and controlling cell proliferation. This study was, therefore, undertaken on the expression of miRNAs, regulation of cyclins and cyclin-dependent kinases (CDKs) in an experimental condition that precedes a tumorigenic response. Male SD rats were treated with aniline (1 mmol/kg/day by gavage) for 7 days, and expression of miRNAs, cyclins and CDKs in rat spleens were analyzed. Microarray and/or qPCR analyses showed that aniline exposure led to significantly decreased miRNA expression of let-7a, miR-24, miR-34c, miR-100, miR-125b, and greatly increased miR-181a. The aberrant expression of miRNAs was associated with significantly increased protein expression of cyclins A, B1, D3 and E. Furthermore, remarkably enhanced expression of CDKs like CDK1, CDK2, CDK4, CDK6, especially p-CDK1 and p-CDK2 as well as alternations in the expression of pRB, p27, and CDC25A in the spleens of aniline-treated rats was also observed. The data suggest that aniline exposure leads to aberrant expression of miRNAs in the spleen which could be important in the regulation of cell cycle proteins. Our findings, thus, provide new insight into the role of miRNAs in cell cycle progression, which may contribute to aniline-induced tumorigenic response in the spleen.

PLK1-associated microRNAs are correlated with pediatric medulloblastoma prognosis

PURPOSE

Medulloblastoma (MB) is the most common malignant tumor of the central nervous system (CNS) in children. Despite its relative good survival rates, treatment can cause long time sequels and may impair patients' lifespan and quality, making the search for new treatment options still necessary. Polo like kinases (PLKs) constitute a five-member serine/threonine kinases family (PLK 1-5) that regulates different stages during cell cycle. Abnormal PLKs expression has been observed in several cancer types, including MB. As gene regulators, miRNAs have also been described with variable expression in cancer.

METHODS

We evaluated gene expression profiles of all PLK family members and related miRNAs (miR-100, miR-126, miR-219, and miR-593*) in MB cell lines and tumor samples.

RESULTS

RT-qPCR analysis revealed increased levels of PLK1-4 in all cell lines and in most MB samples, while PLK5 was found underexpressed. In parallel, miR-100 was also found upregulated while miR-129, miR-216, and miR-593* were decreased in MB cell lines. Variable miRNAs expression patterns were observed in MB samples. However, a correlation between miR-100 and PLK4 expression was observed, and associations between miR-100, miR-126, and miR-219 expression and overall and event free survival were also evinced in our cohort. Moreover, despite the lack of association with clinico-pathological features, when comparing primary tumors to those relapsed, we found a consistent decrease on PLK2, miR-219, and miR-598* and an increase on miR-100 and miR-126.

CONCLUSION

Specific dysregulation on PLKs and associated miRNAs may be important in MB and can be used to predict prognosis. Although miRNAs sequences are fundamental to predict its target, the cell type may also be consider once that mRNA repertoire can define different roles for specific miRNA in a given cell.

The GSK461364 PLK1 inhibitor exhibits strong antitumoral activity in preclinical neuroblastoma models

Polo-like kinase 1 (PLK1) is a serine/threonine kinase that promotes G2/M-phase transition, is expressed in elevated levels in high-risk neuroblastomas and correlates with unfavorable patient outcome. Recently, we and others have presented PLK1 as a potential drug target for neuroblastoma, and reported that the BI2536 PLK1 inhibitor showed antitumoral actvity in preclinical neuroblastoma models. Here we analyzed the effects of GSK461364, a competitive inhibitor for ATP binding to PLK1, on typical tumorigenic properties of preclinical in vitro and in vivo neuroblastoma models. GSK461364 treatment of neuroblastoma cell lines reduced cell viability and proliferative capacity, caused cell cycle arrest and massively induced apoptosis. These phenotypic consequences were induced by treatment in the low-dose nanomolar range, and were independent of MYCN copy number status. GSK461364 treatment strongly delayed established xenograft tumor growth in nude mice, and significantly increased survival time in the treatment group. These preclinical findings indicate PLK1 inhibitors may be effective for patients with high-risk or relapsed neuroblastomas with upregulated PLK1 and might be considered for entry into early phase clinical trials in pediatric patients.

MiR-509-3-5p causes aberrant mitosis and anti-proliferative effect by suppression of PLK1 in human lung cancer A549 cells

MicroRNAs (miRNAs) are potent post-transcriptional regulators of gene expression and play roles in DNA damage response (DDR). PLK1 is identified as a modulator of DNA damage checkpoint. Although down-regulation of PLK1 by certain microRNAs has been reported, little is known about the interplay between PLK1 and miR-509-3-5p in DDR. Here we have demonstrated that miR-509-3-5p repressed PLK1 expression by targeting PLK1 3'-UTR, thereby causing mitotic aberration and growth arrest of human lung cancer A549 cells. Repression of PLK1 by miR-509-3-5p was further evidenced by over-expression of miR-509-3-5p in A549, HepG2 and HCT116p53(-/-) cancer cells, in which PLK1 protein was suppressed. Consistently, miR-509-3-5p was stimulated, while PLK1 protein was down-regulated in A549 cells exposed to CIS and ADR, suggesting that suppression of PLK1 by miR-509-3-5p is a component of CIS/ADR-induced DDR pathway. Flow cytometry and immunofluorescence labeling showed that over-expression of miR-509-3-5p in A549 induced G2/M arrest and aberrant mitosis characterized by abnormal bipolar mitotic spindles, condensed chromosomes, lagging DNA and chromosome bridges. In addition, over-expression of miR-509-3-5p markedly blocked A549 cell proliferation and sensitized the cells to CIS and ADR treatment. Taken together, miR-509-3-5p is a feasible suppressor for cancer by targeting PLK1. Our data may provide aid in potential design of combined chemotherapy and in our better understanding of the roles of microRNAs in response to DNA damage.

HBV polymerase overexpression due to large core gene deletion enhances hepatoma cell growth by binding inhibition of microRNA-100

Different types of hepatitis B virus (HBV) core gene deletion mutants were identified in chronic hepatitis B patients. However, their clinical roles in different stages of natural chronic HBV infection remained unclear. To address this issue, HBV core genes were sequenced in three gender- and age-matched patient groups diagnosed as chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC), respectively. Functional analysis of the identified mutants was performed. A novel type of large-fragment core gene deletion (LFCD) was identified exclusively in HCC patients and significantly associated with unfavorable postoperative survival. The presence of LFCDs resulted in generation of precore-polymerase fusion protein or brought the polymerase reading frame under direct control of HBV precore/core promoter, leading to its over-expression. Enhanced cell proliferation and increased tumorigenicity in nude mice were found in hepatoma cells expressing LFCDs. Because of the epsilon-binding ability of HBV polymerase, we hypothesized that the over-expressed polymerase carrying aberrant amino-terminal sequence could bind to cellular microRNAs. Screening of a panel of microRNAs revealed physical association of a precore-polymerase fusion protein with microRNA-100. A binding inhibition effect on microRNA-100 by the precore-polymerase fusion protein with up-regulation of its target, polo-like kinase 1 (PLK1), was discovered. The binding inhibition and growth promoting effects could be reversed by overexpressing microRNA-100. Together, HCC patients carrying hepatitis B large-fragment core gene deletion mutants had an unfavorable postoperative prognosis. The growth promoting effect was partly due to polymerase overexpression, leading to binding inhibition of microRNA-100 and up-regulation of PLK1.

MicroRNA-100 promotes the autophagy of hepatocellular carcinoma cells by inhibiting the expression of mTOR and IGF-1R

We found that restoration of miR-100 expression resulted in accumulation of LC3B-II and decrease of p62 in hepatocellular carcinoma (HCC) cells, whereas antagonism of miR-100 reduced the level of LC3B-II. Moreover, a significant correlation between miR-100 downregulation and p62 upregulation was observed in human HCC tissues, suggesting an autophagy-promoting effect of miR-100. Subsequent investigations disclosed that knockdown of Atg7 but not Beclin-1 attenuated the miR-100-induced LC3B-II elevation. Furthermore, miR-100 overexpression caused massive cell death, which was abrogated by both the Atg7 silencing and chloroquine treatment. Simultaneously, miR-100 expression led to increased fraction of cells with Annexin V-staining and loss of mitochondrial potential, implying that miR-100 may promote the Atg7-dependent autophagy and subsequent apoptotic cell death. Consistently, mouse xenograft models revealed that miR-100 inhibited the in vivo growth of HCC cells. We further showed that miR-100 suppressed the expression of mTOR and IGF-1R by binding to their 3′ untranslated region, and knockdown of mTOR or IGF-1R phenocopied the pro-autophagy effect of miR-100, indicating that miR-100 may promote autophagy by reducing mTOR and IGF-1R level. Collectively, our data uncover a new regulatory mechanism of autophagy and a novel function of miR-100, and provide a potential therapeutic target for HCC.

Downregulation of microRNA-100 enhances the ICMT-Rac1 signaling and promotes metastasis of hepatocellular carcinoma cells

Metastasis is responsible for rapid recurrence of hepatocellular carcinoma (HCC) and poor survival of HCC patients. Here we showed that miR-100 downregulation in HCC tissues was significantly associated with venous invasion, advanced TNM stage, tumor nodule without complete capsule, poorer cell differentiation, and shorter recurrence-free survival. Both gain- and loss-of-function studies showed that miR-100 dramatically suppressed the ability of HCC cells to migrate and to invade through Matrigel in vitro. Analyses using mouse orthotopic xenograft model further revealed that xenografts of miR-100-stable-expressing HCC cells displayed a significant reduction in pulmonary metastasis, compared with control group. Subsequent investigations revealed that miR-100 directly inhibited the expression of isoprenylcysteine carboxyl methyltransferase (ICMT) and ras-related C3 botulinum toxin substrate 1 (Rac1) by binding to their 3′-UTRs, and in turn suppressed lamellipodia formation and matrix metallopeptidase 2 (MMP2) activation. Furthermore, knockdown of ICMT and Rac1 phenocopied the anti-metastasis effect of miR-100, whereas overexpression of the constitutively active Rac1 (Q61L) antagonized the function of miR-100. Taken together, miR-100 represses metastasis of HCC cells by abrogating the ICMT-Rac1 signaling. Downregulation of miR-100 contributes to HCC metastasis and the restoration of miR-100 is a potential strategy for cancer therapy.

KRAS-dependent sorting of miRNA to exosomes

Mutant KRAS colorectal cancer (CRC) cells release protein-laden exosomes that can alter the tumor microenvironment. To test whether exosomal RNAs also contribute to changes in gene expression in recipient cells, and whether mutant KRAS might regulate the composition of secreted microRNAs (miRNAs), we compared small RNAs of cells and matched exosomes from isogenic CRC cell lines differing only in KRAS status. We show that exosomal profiles are distinct from cellular profiles, and mutant exosomes cluster separately from wild-type KRAS exosomes. miR-10b was selectively increased in wild-type exosomes, while miR-100 was increased in mutant exosomes. Neutral sphingomyelinase inhibition caused accumulation of miR-100 only in mutant cells, suggesting KRAS-dependent miRNA export. In Transwell co-culture experiments, mutant donor cells conferred miR-100-mediated target repression in wild-type-recipient cells. These findings suggest that extracellular miRNAs can function in target cells and uncover a potential new mode of action for mutant KRAS in CRC.

KRAS-dependent sorting of miRNA to exosomes

Mutant KRAS colorectal cancer (CRC) cells release protein-laden exosomes that can alter the tumor microenvironment. To test whether exosomal RNAs also contribute to changes in gene expression in recipient cells, and whether mutant KRAS might regulate the composition of secreted microRNAs (miRNAs), we compared small RNAs of cells and matched exosomes from isogenic CRC cell lines differing only in KRAS status. We show that exosomal profiles are distinct from cellular profiles, and mutant exosomes cluster separately from wild-type KRAS exosomes. miR-10b was selectively increased in wild-type exosomes, while miR-100 was increased in mutant exosomes. Neutral sphingomyelinase inhibition caused accumulation of miR-100 only in mutant cells, suggesting KRAS-dependent miRNA export. In Transwell co-culture experiments, mutant donor cells conferred miR-100-mediated target repression in wild-type-recipient cells. These findings suggest that extracellular miRNAs can function in target cells and uncover a potential new mode of action for mutant KRAS in CRC.

Combination of exosomes and circulating microRNAs may serve as a promising tumor marker complementary to alpha-fetoprotein for early-stage hepatocellular carcinoma diagnosis in rats

PURPOSE

Due to unsatisfying prognosis of AFP for hepatocellular carcinoma (HCC), we aim to evaluate the prognostic value of combination of exosomes and miRNAs in detecting HCC.

METHODS

HCC was induced with diethylnitrosamine in rats and using a scoring system based on histological examination six different stages (normal liver, degeneration, fibrosis, cirrhosis, early HCC and late HCC) were identified in the development of HCC. The expression levels of AFP, exosomes and miRNAs (miRNA-10b, miRNA-21, miRNA-122 and miRNA-200a) were detected in both tissue and blood samples from those six stages. Receiver operating characteristic (ROC) curve analysis was conducted to evaluate the power of each parameter and their different combinations in diagnosing HCC or cirrhosis.

RESULTS

A change in the expression of both exosomes and miRNAs was observed during cirrhosis, which in contrast with AFP starts showing up until the early HCC stage. Interestingly, the expressions of exosomes and the selected four miRNAs at early HCC stage obtained more remarkably alterations than the level of AFP (P < 0.05). On correlation analysis, four selected miRNAs had a significant closer relationship with exosomes when compared with AFP. The different combinations of AFP, exosomes, serous miRNAs and exosomal miRNAs had stronger power in predicting HCC than AFP (area under the curve of ROC, 0.943 vs 0.826).

CONCLUSION

To conclude, the combination of circulating miRNAs and exosomes might serve as promising biomarkers for non-virus infected HCC screening and cirrhosis discrimination.

The role of miR-100-mediated Notch pathway in apoptosis of gastric tumor cells

MicroRNAs (miRNAs) are small non-coding regulatory molecules that influence many biological functions, including apoptosis, but their role in the regulation of apoptosis in gastric tumor cells has not been intensively investigated. Here, we showed that miR-100 was specifically upregulated in human epithelium-derived gastric cancer cells and that silencing miR-100 expression in human gastric epithelial cancer cells initiated a robust apoptotic response in vitro. Our in vivo assays indicated that the development of gastric cancer was inhibited by the miR-100 antagonism via initiating apoptosis of tumor. The results presented that antagonism of miR-100 increased the expression level of HS3ST2, the target gene of miR-100, and further resulted in the activation of the Notch-apoptosis pathway in tumor cells. The data also revealed that silencing of miR-100 expression sensitized gastric cancer cells to chemotherapy. Therefore our study presented a novel miR-100 mediated Notch pathway in apoptosis of tumor cells.

By promoting cell differentiation, miR-100 sensitizes basal-like breast cancer stem cells to hormonal therapy

Basal-like breast cancer is an aggressive tumor subtype with a poor response to conventional therapies. Tumor formation and relapse are sustained by a cell subset of Breast Cancer Stem Cells (BrCSCs). Here we show that miR-100 inhibits maintenance and expansion of BrCSCs in basal-like cancer through Polo-like kinase1 (Plk1) down-regulation. Moreover, miR-100 favors BrCSC differentiation, converting a basal like phenotype into luminal. It induces the expression of a functional estrogen receptor (ER) and renders basal-like BrCSCs responsive to hormonal therapy. The key role played by miR-100 in breast cancer free-survival is confirmed by the analysis of a cohort of patients' tumors, which shows that low expression of miR-100 is a negative prognostic factor and is associated with gene signatures of high grade undifferentiated tumors. Our findings indicate a new possible therapeutic strategy, which could make aggressive breast cancers responsive to standard treatments.

Heterogeneity of hepatocellular carcinoma contributes to cancer progression

Hepatocellular carcinoma (HCC) is a highly heterogeneous disease displaying differences in angiogenesis, extracellular matrix proteins, the immune microenvironment and tumor cell populations. Additionally, genetic variations and epigenetic changes of HCC cells could lead to aberrant signaling pathways, induce cancer stem cells and enhance tumor progression. Thus, the heterogeneity in HCC contributes to disease progression and a better understanding of its heterogeneity will greatly aid in the development of strategies for the HCC treatment.

miRNA in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer deaths worldwide. Despite improvements in HCC therapy, the prognosis for HCC patients remains poor due to a high incidence of recurrence. An improved understanding of the pathogenesis of HCC development would facilitate the development of more effective outcomes for the diagnosis and treatment of HCC at earlier stages. miRNA are small, endogenous, non-coding, ssRNA that are 21-30 nucleotides in length and modulate the expression of various target genes at the post-transcriptional and translational levels. Aberrant expression of miRNA is common in various human malignancies and modulates cancer-associated genomic regions or fragile sites. As for the relationship between miRNA and HCC, several studies have demonstrated that the aberrant expression of specific miRNA can be detected in HCC cells and tissues. However, little is known about the mechanisms of miRNA-related cell proliferation and development. In this review, we summarize the central and potential roles of miRNA in the pathogenesis of HCC and elucidate new possibilities that may be useful as diagnostic and prognostic markers, as well as novel therapeutic targets in HCC.

MicroRNA Profiling of Laser-Microdissected Hepatocellular Carcinoma Reveals an Oncogenic Phenotype of the Tumor Capsule

Several microRNAs (miRNAs) are associated with the molecular pathogenesis of hepatocellular carcinoma (HCC). However, previous studies analyzing the dysregulation of miRNAs in HCC show heterogeneous results. We hypothesized that part of this heterogeneity might be attributable to variations of miRNA expression deriving from the HCC capsule or the fibrotic septa within the peritumoral tissue used as controls. Tissue from surgically resected hepatitis C–associated HCC from six well-matched patients was microdissected using laser microdissection and pressure catapulting technique. Four distinct histologic compartments were isolated: tumor parenchyma (TP), fibrous capsule of the tumor (TC), tumor-adjacent liver parenchyma (LP), and cirrhotic septa of the tumor-adjacent liver (LC). MiRNA expression profiling analysis of 1105 mature miRNAs and precursors was performed using miRNA microarray. Principal component analysis and consecutive pairwise supervised comparisons demonstrated distinct patterns of expressed miRNAs not only for TP versus LP (e.g., intratumoral down-regulation of miR-214, miR-199a, miR-146a, and miR-125a; P< .05) but also for TC versus LC (including down-regulation within TC of miR-126, miR-99a/100, miR-26a, and miR-125b; P< .05). The tumor capsule therefore demonstrates a tumor-like phenotype with down-regulation of well-known tumor-suppressive miRNAs. Variations of co-analyzed fibrotic tissue within the tumor or in controls may have profound influence on miRNA expression analyses in HCC. Several miRNAs, which are proposed to be HCC specific, may indeed be rather associated to the tumor capsule. As miRNAs evolve to be important biomarkers in liver tumors, the presented data have important translational implications on diagnostics and treatment in patients with HCC.

The involvement of miR-100 in bladder urothelial carcinogenesis changing the expression levels of mRNA and proteins of genes related to cell proliferation, survival, apoptosis and chromosomal stability

Introduction

MicroRNAs (miRNA) are small non-coding RNAs that play an important role in the control of gene expression by inhibiting protein translation or promoting messenger RNA degradation. Today, miRNAs have been shown to be involved in various physiological and pathological cellular processes, including cancer, where they can act as oncogenes or tumor suppressor genes. Recently, lowered expression of miR-100, resulting in upregulation of FGFR3, has been correlated with low-grade, non-invasive bladder urothelial cancer, as an alternative oncogenesis pathway to the typical FGFR3 gene mutation. Our aim is to analyze the role of miR-100 in bladder cancer cell lines in controlling the expression of some of its possible target genes, including FGFR3 and its relationship with proliferation, apoptosis and DNA ploidy.

Methods

The bladder cancer cell lines RT4 and T24 were transfected with pre-miR 100, anti-miR 100 and their respective controls using a lipid-based formulation. After transfection mRNA and protein levels of its supposed target genes THAP2, BAZ2A, mTOR, SMARCA5 and FGFR3 were analyzed by quantitative real time polymerase chain reaction (qRT-PCR) and western blotting. Cell proliferation, apoptosis and DNA ploidy were analyzed by flow cytometry. For statistical analysis, a t-test was applied, p < 0.05 was considered significant.

Results

After miR-100 transfection, there was a significant reduction in the mRNA of mTOR (p = 0.006), SMARCA5 (p = 0.007) and BAZ2A (p = 0.029) in RT4, mTOR (p = 0.023) and SMARCA5 (p = 0.015) in T24. There was a reduction in the expression of all proteins, variable from 22.5% to 57.1% in both cell lines. In T24 miR-100 promoted an increase in cell proliferation and anti-miR 100 promoted apoptosis characterizing miR-100 as an oncomiR in this cell line representative of a high-grade urothelial carcinoma.

Conclusion

miR-100 transfection reduces expression of BAZ2A, mTOR and SMARCA5 mRNA and protein in BC cell lines. miR-100 would be classified as an oncomiR in T24 cells representative of high grade urothelial carcinoma promoting increase in cell proliferation and reduction in apoptosis. The knowledge of miRNA role in tumors will allow their use as tumor markers and targets for new therapies.

miRNAs: new tools for molecular classification, diagnosis and prognosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most common malignancies worldwide, ranking as the third leading cause of cancer-related death. With recent advances in understanding HCC biology, progress has been made in early detection and management of HCC; however, its prognosis remains dismal. Novel biomarkers for HCC that are acceptable for clinical utility are urgently in need. Recently, miRNA has emerged as an important class of gene regulator that controls various cellular processes including cancer development. In HCC, miRNAs are frequently dysregulated, and studies have shown great promises of miRNAs as biomarkers for tumor classification, diagnosis and prognosis. Given miRNAs are highly stable in blood plasma and serum, they are suggested as a new class of noninvasive biomarker for detection of HCC. In this article, we provide an up-to-date review of the recent findings of the use of miRNAs in molecular classification of HCC tumors, diagnosis and prognosis.

Feasibility of global miRNA analysis from fine-needle biopsy FFPE material in patients with hepatocellular carcinoma treated with sorafenib

The present study demonstrates that miRNA analyses are feasible from fine-needle biopsy specimens and is the first to correlate the response under sorafenib therapy to miRNA expression signatures in hepatocellular carcinoma (HCC). The data do not support that miRNA profiles function as reliable biomarkers for sorafenib response prediction.

MiRNA-99a directly regulates AGO2 through translational repression in hepatocellular carcinoma

The regulation network consisting of microRNAs (miRNAs) and their target genes remains largely elusive in hepatocellular carcinoma (HCC), especially the reciprocal loop between specific miRNAs and the miRNA processing machinery. In this study, we found that miR-99a was remarkably decreased in 111 of 152 (73.03%) primary HCC tissues and low-level expression of miR-99a was correlated with low tumor differentiation (P=0.001), liver cirrhosis (P=0.015), poor tumor-free survival (P=0.004) and overall survival (P=0.006) for HCC patients. By restoration of miR-99a, the HCC growth could be considerably inhibited both in vitro and in vivo. Subsequently, Argonaute-2 (Ago2), a central component of RNA-induced silencing complex, was found to be directly regulated by miR-99a via translational repression. Overexpression of Ago2 could partly impair the inhibitory effect of miR-99a on HCC cells in vitro. Then, we demonstrated that Ago2 was upregulated in HCC tissues at both RNA and protein levels and the expression of AGO2 protein and miR-99a was negatively correlated within detected HCC tissues (r=−0.727, P=0.004). Interestingly, the tumorigenicity of Ago2-knockdown HCC cells was severely impaired (4/10 vs 10/10, P<0.05), and this was in contrast to the miR-99a-overexpressing HCC cells. Functionally, the increased AGO2 protein could specifically facilitate oncogenic miR-21 to repress its targeted gene phosphatase and tensin homolog (Pten) in HCC, whereas leave the regulatory capacity of let-7a on its targeted oncogenes almost unaltered. In summary, our study has revealed a novel pathway for the tumor suppressor miR-99a to control tumor growth in HCC, via its downstream signaling of AGO2/miR-21/PTEN. In addition, this study provides potential strategies for HCC therapy by reintroduction of miRNA suppressors.

The role of microRNAs in hepatocarcinogenesis: current knowledge and future prospects

MicroRNAs (miRNAs) are small, noncoding RNA molecules that regulate gene expression post-transcriptionally through complementary base pairing with thousands of messenger RNAs. Although the precise biological functions of individual miRNAs are still unknown, miRNAs are speculated to play important roles in diverse biological processes through fine regulation of their target gene expression. A growing body of data indicates the deregulation of miRNAs during hepatocarcinogenesis. In this review, we summarize recent findings regarding deregulated miRNA expression and their possible target genes in hepatocarcinogenesis, with emphasis on inflammation-related hepatocarcinogenesis. Because miRNA-based strategies are being applied to clinical therapeutics, precise knowledge of miRNA functions is crucial both scientifically and clinically. We discuss the current open questions from these points of view, which must be clarified in the near future.

Noncoding RNAs in DNA repair and genome integrity

SIGNIFICANCE

The well-studied sequences in the human genome are those of protein-coding genes, which account for only 1%-2% of the total genome. However, with the advent of high-throughput transcriptome sequencing technology, we now know that about 90% of our genome is extensively transcribed and that the vast majority of them are transcribed into noncoding RNAs (ncRNAs). It is of great interest and importance to decipher the functions of these ncRNAs in humans.

RECENT ADVANCES

In the last decade, it has become apparent that ncRNAs play a crucial role in regulating gene expression in normal development, in stress responses to internal and environmental stimuli, and in human diseases.

CRITICAL ISSUES

In addition to those constitutively expressed structural RNA, such as ribosomal and transfer RNAs, regulatory ncRNAs can be classified as microRNAs (miRNAs), Piwi-interacting RNAs (piRNAs), small interfering RNAs (siRNAs), small nucleolar RNAs (snoRNAs), and long noncoding RNAs (lncRNAs). However, little is known about the biological features and functional roles of these ncRNAs in DNA repair and genome instability, although a number of miRNAs and lncRNAs are regulated in the DNA damage response.

FUTURE DIRECTIONS

A major goal of modern biology is to identify and characterize the full profile of ncRNAs with regard to normal physiological functions and roles in human disorders. Clinically relevant ncRNAs will also be evaluated and targeted in therapeutic applications.

MicroRNA/gene profiling unveils early molecular changes and nuclear factor erythroid related factor 2 (NRF2) activation in a rat model recapitulating human hepatocellular carcinoma (HCC)

Studies on gene and/or microRNA (miRNA) dysregulation in the early stages of hepatocarcinogenesis are hampered by the difficulty of diagnosing early lesions in humans. Experimental models recapitulating human hepatocellular carcinoma (HCC) are then used to perform this analysis. We performed miRNA and gene expression profiling to characterize the molecular events involved in the multistep process of hepatocarcinogenesis in the resistant-hepatocyte rat model. A high percentage of dysregulated miRNAs/genes in HCC were similarly altered in early preneoplastic lesions positive for the stem/progenitor cell marker cytokeratin-19, indicating that several HCC-associated alterations occur from the very beginning of the carcinogenic process. Our analysis also identified miRNA/gene-target networks aberrantly activated at the initial stage of hepatocarcinogenesis. Activation of the nuclear factor erythroid related factor 2 (NRF2) pathway and up-regulation of the miR-200 family were among the most prominent changes. The relevance of these alterations in the development of HCC was confirmed by the observation that NRF2 silencing impaired while miR-200a overexpression promoted HCC cell proliferation in vitro. Moreover, T3-induced in vivo inhibition of the NRF2 pathway accompanied the regression of cytokeratin-19-positive nodules, suggesting that activation of this transcription factor contributes to the onset and progression of preneoplastic lesions towards malignancy. The finding that 78% of genes and 57% of dysregulated miRNAs in rat HCC have been previously associated with human HCC as well underlines the translational value of our results.

CONCLUSION

This study indicates that most of the molecular changes found in HCC occur in the very early stages of hepatocarcinogenesis. Among these, the NRF2 pathway plays a relevant role and may represent a new therapeutic target.

β-ionone inhibits persistent preneoplastic lesions during the early promotion phase of rat hepatocarcinogenesis: TGF-α, NF-κB, and p53 as cellular targets

Dietary isoprenic derivatives such as β-ionone (βI) are a promising class of chemopreventive agents. In this study, cellular aspects of βI protective activities during early hepatocarcinogenesis were evaluated. Male Wistar rats were submitted to "resistant hepatocyte" model and then received daily 16 mg/100 g body weight (b.w.) of βI (βI group) or only 0.25 mL/100 g b.w. of corn oil (vehicle, control group [CO]) during 4 wk, specifically during early promotion phase. Compared to controls, βI inhibited (P < 0.05) the development of persistent preneoplastic lesions (pPNL), considered to be potential hepatocellular carcinoma (HCC) progression sites, and increased remodeling PNL (rPNL) (P < 0.05) that tend to regress to a normal phenotype. Increased βI hepatic levels (P < 0.05), in the βI group, were associated with its chemopreventive actions. Compared to control rats, βI reduced the frequency of both pPNL and rPNL positive for tumor growth factor (TGF)-α (P < 0.05), reduced the frequency of pPNL stained for p65 (nuclear factor-kappaB; NF-κB) (P < 0.05), and reduced the frequency of pPNL positive for cytoplasmic p53 (P < 0.05). Our data demonstrated that βI targets TGF-α, NF-κB, and p53 in initial phases of hepatocarcinogenesis and specifically inhibits PNL with increased probability to progress to HCC. This isoprenoid may represent a chemopreventive agent of choice for HCC control.

MicroRNA-100 inhibits osteosarcoma cell proliferation by targeting Cyr61

Increasing evidence indicates that microRNAs (miRNAs) participate in almost every step of cellular processes and are often aberrantly expressed in human cancer. Therefore, the discovery of miRNAs may provide a new and powerful tool for understanding the mechanism and treatment of carcinogenesis. The aim of this study was to investigate the functional significance of miR-100 and to identify its possible target genes in osteosarcoma (OS) cells. Here, we found that expression level of miR-100 was significantly decreased in osteosarcoma tissues in comparison with the adjacent normal tissues. The enforced expression of miR-100 was able to inhibit cell proliferation in Saos-2 and MG63 cells, while its antisense oligonucleotides (antisense miR-100) promoted cell proliferation. Moreover, our results further revealed that expression of Cyr61, an extracellular matrix-associated growth factor, was negatively regulated by miR-100. Therefore, we consider that miR-100 acts as a tumor suppressor for osteosarcoma. It may provide novel diagnostic and therapeutic options for human osteosarcoma in the future.

The role of polo-like kinase 1 in carcinogenesis: cause or consequence?

Polo-like kinase 1 (Plk1) is a well-established mitotic regulator with a diverse range of biologic functions continually being identified throughout the cell cycle. Preclinical evidence suggests that the molecular targeting of Plk1 could be an effective therapeutic strategy in a wide range of cancers; however, that success has yet to be translated to the clinical level. The lack of clinical success has raised the question of whether there is a true oncogenic addiction to Plk1 or if its overexpression in tumors is solely an artifact of increased cellular proliferation. In this review, we address the role of Plk1 in carcinogenesis by discussing the cell cycle and DNA damage response with respect to their associations with classic oncogenic and tumor suppressor pathways that contribute to the transcriptional regulation of Plk1. A thorough examination of the available literature suggests that Plk1 activity can be dysregulated through key transformative pathways, including both p53 and pRb. On the basis of the available literature, it may be somewhat premature to draw a definitive conclusion on the role of Plk1 in carcinogenesis. However, evidence supports the notion that oncogene dependence on Plk1 is not a late occurrence in carcinogenesis and it is likely that Plk1 plays an active role in carcinogenic transformation.

Downregulation of microRNA-100 correlates with tumor progression and poor prognosis in hepatocellular carcinoma

Increasing evidence suggests that dysregulation of microRNAs is correlated with malignant transformation and tumor development. miR-100, a potential tumor suppressor, is downregulated by many human cancers. However, the expression and functions of miR-100 in hepatocellular carcinoma (HCC) are still unclear. The aim of this study was to detect the expression of miR-100 in HCC tissues and investigate its clinicopathological and prognostic significance. Also, the effects of miR-100 on growth and apoptosis of HCC cells and its potential molecular mechanisms were analyzed. Results showed that the expression level of miR-100 in HCC tissues was significantly lower than that in matched non-cancerous liver tissues. Also, low-miR-100 expression was observed to be significantly correlated with higher tumor grade, higher incidence of lymph node metastasis, advanced TNM stage and higher incidence of tumor recurrence in HCC patients. Multivariate survival analyses suggested that low-miR-100 expression was an independent prognostic factor for HCC patients (HR = 1.66, 95 % CI 1.32-2.82, P = 0.019). In addition, we found that upregulation of miR-100 could inhibit growth and increase apoptosis of HCC cells by downregulating polo-like kinase 1 (plk1). In HCC tissues, miR-100 expression was inversely correlated with the expression of plk1 protein (r = -0.418; P = 0.029). Therefore, downregulation of miR-100 was correlated with progressive pathological feature and poor prognosis in HCC patients, and miR-100 could function as a tumor suppressor by targeting plk1. miR-100 may serve as a prognostic marker and molecular therapeutic target in HCC.