miR-21 expression predicts prognosis in hepatocellular carcinoma

microRNA 21 and long non-coding RNAs interplays underlie cancer pathophysiology: A narrative review

Non-coding RNAs (ncRNAs) are a diverse group of functional RNA molecules that lack the ability to code for proteins. Despite missing this traditional role, ncRNAs have emerged as crucial regulators of various biological processes and have been implicated in the development and progression of many diseases, including cancer. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two prominent classes of ncRNAs that have emerged as key players in cancer pathophysiology. In particular, miR-21 has been reported to exhibit oncogenic roles in various forms of human cancer, including prostate, breast, lung, and colorectal cancer. In this context, miR-21 overexpression is closely associated with tumor proliferation, growth, invasion, angiogenesis, and chemoresistance, whereas miR-21 inactivation is linked to the regression of most tumor-related processes. Accordingly, miR-21 is a crucial modulator of various canonical oncogenic pathways such as PTEN/PI3K/Akt, Wnt/β-catenin, STAT, p53, MMP2, and MMP9. Moreover, interplays between lncRNA and miRNA further complicate the regulatory mechanisms underlying tumor development and progression. In this regard, several lncRNAs have been found to interact with miR-21 and, by functioning as competitive endogenous RNAs (ceRNAs) or miRNA sponges, can modulate cancer tumorigenesis. This work presents and discusses recent findings highlighting the roles and pathophysiological implications of the miR-21-lncRNA regulatory axis in cancer occurrence, development, and progression. The data collected indicate that specific lncRNAs, such as MEG3, CASC2, and GAS5, are strongly associated with miR-21 in various types of cancer, including gastric, cervical, lung, and glioma. Indeed, these lncRNAs are well-known tumor suppressors and are commonly downregulated in different types of tumors. Conversely, by modulating various mechanisms and oncogenic signaling pathways, their overexpression has been linked with preventing tumor formation and development. This review highlights the significance of these regulatory pathways in cancer and their potential for use in cancer therapy as diagnostic and prognostic markers.

A comprehensive review of miR-21 in liver disease: Big impact of little things

microRNAs (miRNAs), a class of non-coding RNA with 20-24 nucleotides, are defined as the powerful regulators for gene expression. miR-21 is a multifunctional miRNA enriched in the circulatory system and multiple organs, which not only serves as a non-invasive biomarker in disease diagnosis, but also participates in many cellular activities. In various chronic liver diseases, the increase of miR-21 affects glycolipid metabolism, viral infection, inflammatory and immune cell activation, hepatic stellate cells activation and tissue fibrosis, and autophagy. Moreover, miR-21 is also a liaison in the deterioration of chronic liver disease to hepatocellular carcinoma (HCC), and it impacts on cell proliferation, apoptosis, migration, invasion, angiogenesis, immune escape, and epithelial-mesenchymal transformation by regulating target genes expression in different signaling pathways. In current research on miRNA therapy, some natural products can exert the hepatoprotective effects depending on the inhibition of miR-21 expression. In addition, miR-21-based therapeutic also play a role in regulating intracellular miR-21 levels and enhancing the efficacy of chemotherapy drugs. Herein, we systemically summarized the recent progress of miR-21 on biosynthesis, biomarker function, molecular mechanism and miRNA therapy in chronic liver disease and HCC, and looked forward to outputting some information to enable it from bench to bedside.

MiRNAs in Alcohol-Related Liver Diseases and Hepatocellular Carcinoma: A Step toward New Therapeutic Approaches?

Alcohol-related Liver Disease (ALD) is the primary cause of chronic liver disorders and hepatocellular carcinoma (HCC) development in developed countries and thus represents a major public health concern. Unfortunately, few therapeutic options are available for ALD and HCC, except liver transplantation or tumor resection for HCC. Deciphering the molecular mechanisms underlying the development of these diseases is therefore of major importance to identify early biomarkers and to design efficient therapeutic options. Increasing evidence indicate that epigenetic alterations play a central role in the development of ALD and HCC. Among them, microRNA importantly contribute to the development of this disease by controlling the expression of several genes involved in hepatic metabolism, inflammation, fibrosis, and carcinogenesis at the post-transcriptional level. In this review, we discuss the current knowledge about miRNAs' functions in the different stages of ALD and their role in the progression toward carcinogenesis. We highlight that each stage of ALD is associated with deregulated miRNAs involved in hepatic carcinogenesis, and thus represent HCC-priming miRNAs. By using in silico approaches, we have uncovered new miRNAs potentially involved in HCC. Finally, we discuss the therapeutic potential of targeting miRNAs for the treatment of these diseases.

Value of miR-21 levels as potential biomarkers in the early diagnosis of hepatocellular carcinoma：a meta-analysis

BACKGROUND

Many studies have reported that miR-21 levels are different between hepatocellular carcinoma (HCC) patients and healthy controls, which could be used as a potential diagnostic biomarker for HCC. However, the diagnostic value of miR-21 for HCC varied greatly in previous studies. Therefore, this meta-analysis aims to provide higher grade evidence to investigate the diagnostic value of miR-21 for HCC.

METHODS

The databases of PubMed, Embase, Web of Science, and Chinese databases (CNKI and VIP) were searched. The indices of miR-21 in the diagnosis of HCC were pooled using bivariate random-effect models. QUADAS-2 was used to evaluate the quality of included studies. All statistical analyses were performed by STATA (12.0) software.

RESULTS

Totally, 1589 subjects from 14 publications were included in this study. The pooled sensitivity, specificity, positive likelihood ratios (PLR), negative likelihood ratios (NLR), and area under the curve (AUC) were 0.83 (0.77-0.88), 0.80 (0.74-0.85), 4.12 (3.04-5.57), 0.21 (0.15-0.30), and 0.88 (0.85-0.91), respectively. Subgroup analysis showed that the AUC was higher in Non-China subgroup, qRT-PCR subgroup, and plasma subgroup than that in China subgroup, ddPCR subgroup, and serum subgroup, respectively. However, the AUC was not significantly different between the healthy control subgroup and chronic hepatitis control subgroup. Significant heterogeneity was found in this meta-analysis, while no evident publication bias was identified.

CONCLUSIONS

miR-21 is a valuable biomarker for the early diagnosis of HCC.

miRcorrNet: machine learning-based integration of miRNA and mRNA expression profiles, combined with feature grouping and ranking

A better understanding of disease development and progression mechanisms at the molecular level is critical both for the diagnosis of a disease and for the development of therapeutic approaches. The advancements in high throughput technologies allowed to generate mRNA and microRNA (miRNA) expression profiles; and the integrative analysis of these profiles allowed to uncover the functional effects of RNA expression in complex diseases, such as cancer. Several researches attempt to integrate miRNA and mRNA expression profiles using statistical methods such as Pearson correlation, and then combine it with enrichment analysis. In this study, we developed a novel tool called miRcorrNet, which performs machine learning-based integration to analyze miRNA and mRNA gene expression profiles. miRcorrNet groups mRNAs based on their correlation to miRNA expression levels and hence it generates groups of target genes associated with each miRNA. Then, these groups are subject to a rank function for classification. We have evaluated our tool using miRNA and mRNA expression profiling data downloaded from The Cancer Genome Atlas (TCGA), and performed comparative evaluation with existing tools. In our experiments we show that miRcorrNet performs as good as other tools in terms of accuracy (reaching more than 95% AUC value). Additionally, miRcorrNet includes ranking steps to separate two classes, namely case and control, which is not available in other tools. We have also evaluated the performance of miRcorrNet using a completely independent dataset. Moreover, we conducted a comprehensive literature search to explore the biological functions of the identified miRNAs. We have validated our significantly identified miRNA groups against known databases, which yielded about 90% accuracy. Our results suggest that miRcorrNet is able to accurately prioritize pan-cancer regulating high-confidence miRNAs. miRcorrNet tool and all other supplementary files are available at https://github.com/malikyousef/miRcorrNet.

Dairy consumption and hepatocellular carcinoma risk

This review provides epidemiological and translational evidence for milk and dairy intake as critical risk factors in the pathogenesis of hepatocellular carcinoma (HCC). Large epidemiological studies in the United States and Europe identified total dairy, milk and butter intake with the exception of yogurt as independent risk factors of HCC. Enhanced activity of mechanistic target of rapamycin complex 1 (mTORC1) is a hallmark of HCC promoted by hepatitis B virus (HBV) and hepatitis C virus (HCV). mTORC1 is also activated by milk protein-induced synthesis of hepatic insulin-like growth factor 1 (IGF-1) and branched-chain amino acids (BCAAs), abundant constituents of milk proteins. Over the last decades, annual milk protein-derived BCAA intake increased 3 to 5 times in Western countries. In synergy with HBV- and HCV-induced secretion of hepatocyte-derived exosomes enriched in microRNA-21 (miR-21) and miR-155, exosomes of pasteurized milk as well deliver these oncogenic miRs to the human liver. Thus, milk exosomes operate in a comparable fashion to HBV- or HCV- induced exosomes. Milk-derived miRs synergistically enhance IGF-1-AKT-mTORC1 signaling and promote mTORC1-dependent translation, a meaningful mechanism during the postnatal growth phase, but a long-term adverse effect promoting the development of HCC. Both, dietary BCAA abundance combined with oncogenic milk exosome exposure persistently overstimulate hepatic mTORC1. Chronic alcohol consumption as well as type 2 diabetes mellitus (T2DM), two HCC-related conditions, increase BCAA plasma levels. In HCC, mTORC1 is further hyperactivated due to RAB1 mutations as well as impaired hepatic BCAA catabolism, a metabolic hallmark of T2DM. The potential HCC-preventive effect of yogurt may be caused by lactobacilli-mediated degradation of BCAAs, inhibition of branched-chain α-ketoacid dehydrogenase kinase via production of intestinal medium-chain fatty acids as well as degradation of milk exosomes including their oncogenic miRs. A restriction of total animal protein intake realized by a vegetable-based diet is recommended for the prevention of HCC.

Overexpression of Taspase 1 Predicts Poor Prognosis in Patients with Hepatocellular Carcinoma

Background

Taspase 1 (TASP1) is a highly conserved protease involved in site-specific proteolysis. Existing researches have revealed a link between TASP1 expression and carcinogenesis. However, limited data are available regarding the prognosis and functions of TASP1 in hepatocellular carcinoma (HCC).

Methods

Western Blotting and qRT-PCR were employed to evaluate the level of TASP1 in HCC cell lines and clinical specimens. TASP1 expression was further calculated in clinical specimens by immunohistochemistry and the mRNA level of TASP1 in HCC was analyzed using Oncomine and UALCAN databases. The TASP1 promoter methylation modification was shown via MEXPRESS and UALCAN. The association between TASP1 expression and postoperative prognosis was evaluated using Kaplan–Meier and Cox regression analysis in clinical patients. The effect of TASP1 on HCC prognosis was analyzed via Kaplan-Meier plotter, GEPIA and UALCAN. Additionally, the regulators, kinases, miRNA and transcription factor targets of TASP1 were identified using LinkedOmics. Moreover, cBioPortal was used to detect the genetic alteration of TASP1. Finally, TIMER was utilized to assess the relation between TASP1 and the immune cell infiltration, whereas the correlation of TASP1 with three immune factors was detected through TISIDB.

Results

TASP1 expression was increased in HCC cell lines and HCC tissues. CNV and DNA methylation of TASP1 were changed. Survival analysis revealed that high TASP1 expression was correlated with overall survival (OS). Functional network analysis about TASP1 in HCC showed that the double-strand break repair, peptidyl-threonine modification, spindle organization, peptidyl-lysine modification and microtubule-based movement were modulated. Furthermore, TASP1 expression revealed puissant relation to the infiltration of immune cells and three immune factors in HCC.

Conclusion

These data indicate that TASP1 may act as a potential prognostic marker in HCC and regulate HCC via multiple mechanisms.

The Prognostic Significance of miR-21 Expression among Surgically Resected Hepatocellular Carcinoma Patients: Evidence from a Meta-Analysis and Retrospective Cohort Study

Background

To date, microRNA-21 (miR-21) has been reported to be associated with the prognosis of hepatocellular carcinoma (HCC) in various studies, yet the results were inconsistent. The purpose of this two-part study, consisting of a retrospective cohort study and a meta-analysis, sets out to determine the prognostic role of miR-21 expression among HCC patients who underwent surgical resection. Methods. In this study, we first detected miR-21 expression in HCC patients by quantitative real-time PCR (qRT-PCR). Patients were divided into a high miR-21 expression group and a low miR-21 expression group according to the median level of miR-21 expression in tumor tissues. The survival outcomes of the two groups were analyzed by the Kaplan-Meier method with the log-rank test. Multivariate analysis of the prognostic factors was performed with the Cox regression model. Subsequently, eligible studies were obtained by searching on PubMed, Cochrane Library, and Web of Science, and a meta-analysis was performed to assess the prognostic role of miR-21 expression among HCC.

Results

The qRT-PCR analysis results of our cohort study showed miR-21 expression was significantly upregulated in HCC tissues when compared with adjacent nontumor tissues. Multivariate analysis suggested that miR-21 expression was an independent prognostic factor for overall survival (OS) (hazard ratio, HR = 2.361) and disease-free survival (DFS) (HR = 2.024) in HCC patients who underwent surgical resection. A total of 10 studies with 969 patients were enrolled in the meta-analysis, consisting of 9 studies from the database search and our cohort study. We observed that elevated miR-21 expression can predict poor OS (HR = 2.24, 95%CI = 1.73-2.91, P < 0.001) and DFS/recurrence-free survival (RFS) (HR = 2.44, 95%CI = 1.62-3.67, P < 0.001) in surgically resected HCC patients.

Conclusions

Our study demonstrated that miR-21 high expression among surgically resected HCC patients is a prognostic factor that indicated adverse survival.

Circulating miR-21-5p level has limited prognostic value in patients with hepatocellular carcinoma and is influenced by renal function

BACKGROUND

MicroRNAs (miRNAs) have been suggested as biomarkers for malignant diseases including hepatocellular carcinoma (HCC). Specifically, hsa-miR-21-5p (miR-21) is among the most frequently deregulated miRNA in cancer. The diagnostic and prognostic value of miR-21 has been demonstrated in HCC tissue, mostly in the Asian population. Although the impact of various factors has been recently reported for circulating hsa-miR-122-5p (miR-122), at present only limited knowledge is available for miR-21.

AIM

To evaluate the value of miR-21 for the assessment of prognosis in HCC patients and to delineate the influence of clinical and preanalytical factors on miR-21 level in sera.

METHODS

Patients with confirmed HCC from our European cohort with predominantly alcohol-associated liver damage were included in the study. All subjects were characterized according to their clinical and laboratory work-up and overall survival data were obtained. Quantitative real-time polymerase chain reaction was performed for miR-21 and spiked-in cel-miR-39-3p. The results were compared to previously reported miR-122 data.

RESULTS

Survival of HCC patients was comparable between patients with low and high serum miR-21 concentration. No association was observed between miR-21 level in sera and Child-Pugh score, Barcelona Clinic Liver Cancer staging system, or etiology of HCC/liver disease. Age, gender, or pretreatment had no association with miR-21 level. A positive correlation was observed between miR-21 and aspartate aminotransferase (r = 0.2854, P = 0.0061), serum miR-122 (r = 0.2624, P = 0.0120), and the International Normalized Ratio (r = 0.2065, P = 0.0496). Negative correlation of miR-21 with serum creatinine (r = -0.2215, P = 0.0348) suggests renal function as a potential influencing factor in miR-21 biogenesis in blood.

CONCLUSION

The results from this work do not support clinically relevant prognostic value of circulating miR-21 in HCC patients in real-life settings. Following systematic evaluation, we identified renal function and aspartate aminotransferase as potential factors that may affect miR-21 concentration in blood. This knowledge should be considered in future miRNA-based biomarker studies not only for HCC but also for other diseases.

Dysregulated microRNAs in Hepatitis B Virus-Related Hepatocellular Carcinoma: Potential as Biomarkers and Therapeutic Targets

MicroRNAs (miRNAs) are non-coding small RNAs that can function as gene regulators and are involved in tumorigenesis. We review the commonly dysregulated miRNAs in liver tumor tissues and plasma/serum of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) patients. The frequently reported up-regulated miRNAs in liver tumor tissues include miR-18a, miR-21, miR-221, miR-222, and miR-224, whereas down-regulated miRNAs include miR-26a, miR-101, miR-122, miR-125b, miR-145, miR-199a, miR-199b, miR-200a, and miR-223. For a subset of these miRNAs (up-regulated miR-222 and miR-224, down-regulated miR-26a and miR-125b), the pattern of dysregulated circulating miRNAs in plasma/serum is mirrored in tumor tissue based on multiple independent studies. Dysregulated miRNAs target oncogenes or tumor suppressor genes involved in hepatocarcinogenesis. Normalization of dysregulated miRNAs by up- or down-regulation has been shown to inhibit HCC cell proliferation or sensitize liver cancer cells to chemotherapeutic treatment. miRNAs hold as yet unrealized potential as biomarkers for early detection of HCC and as precision therapeutic targets, but further studies in diverse populations and across all stages of HCC are needed.

Epithelial cell -derived microvesicles: A safe delivery platform of CRISPR/Cas9 conferring synergistic anti-tumor effect with sorafenib

Safe and efficient intracellular delivery of CRISPR/Cas9 is a key step for effective therapeutic genome editing in a wide range of diseases. This remains challenging due to multiple drawbacks of the currently available vehicles. Here we report that epithelial cell -derived microvesicles (MVs) function as safe and natural carriers for efficient delivery of CRISPR/Cas9 to treat cancer. In our study, compared to epithelial cell -derived MVs, cancer -derived MVs were quickly absorbed intracellularly by recipient cancer cells in vitro and showed selective accumulation in tumors of HepG2 xenografts in vivo, due to their cancer cell tropism dependent targeting. Surprisingly, synergistic anti-tumor effect of sgIQ 1.1 loaded Cas9MVs/HEK293 + sorafenib was better than sgIQ 1.1 + Cas9MVs/HepG2 + sorafenib in vitro. In addition, qPCR results showed that miR-21 and miR-181a expression were upregulated in HepG2 cells treated with cancer cell -derived MVs that might support the cancer progression. Further, treatment of HepG2 xenografts with sgIQ 1.1 loaded Cas9MVs/HEK293 showed enhanced anti-cancer effect than sgIQ 1.1 + Cas9MVs/HepG2. Therefore, we conclude that normal cells -derived MVs can act as better and safe natural delivery systems for cancer therapeutics in the future.

Prognostic value of miR-21 in gliomas: comprehensive study based on meta-analysis and TCGA dataset validation

Recent studies have highlighted the value of microRNA-21 (miR-21) as a prognostic biomarker in gliomas. However, the role of miR-21 in predicting prognosis remains controversial. We performed a comprehensive study based upon a meta-analysis and The Cancer Genome Atlas (TCGA) glioma dataset validation to clarify the prognostic significance of miR-21 in glioma patients. In this study, we searched Embase, PubMed, Web of science, CNKI, SinoMed, and Wanfang databases for records up to May 2018. Relevant data were extracted to assess the correlation between miR-21 expression and survival in glioma patients. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were used to describe association strength. We further used multivariate Cox regression analysis to assess miR-21 expression in the TCGA glioma dataset to validate the relationship between miR-21 expression and survival. Nine studies were included in the meta-analysis. Among them, eight studies provided data on overall survival (OS) with a pooled HR of 1.91 (95% CI: 1.34, 2.73), indicating that higher expression of miR-21 was significantly associated with worse OS in glioma patients; for the other study, which provided data on progression-free survival (PFS), no statistically significant HR was reported for PFS in the glioma patients (HR = 1.23, 95% CI: 0.41, 3.72). A multivariate Cox regression analysis of the miR-21 expression in the TCGA glioma dataset revealed that overexpression of miR-21 was a potential independent prognostic biomarker of poorer OS (HR = 1.27, 95% CI: 1.01, 1.59) and poorer PFS (HR = 1.46, 95% CI: 1.17, 1.82). Our findings suggest that higher expression of miR-21 is correlated with poorer glioma prognosis.

LncRNA growth arrest-specific transcript 5 targets miR-21 gene and regulates bladder cancer cell proliferation and apoptosis through PTEN

The aim of this study was to investigate the mechanism by which growth arrest‐specific transcript 5 (GAS5) regulates bladder cancer cells. Bladder cancer samples were collected and tested for experiment. Dual‐luciferase reporter assay was used to verify the downstream target genes for GAS5 and miR‐21. The expression level of GAS5 was decreased and that of miR‐21 was increased, indicating a negative correlation between the two. Patients with high GAS5 level and low miR‐21 level had relatively longer survival rates. GAS5 inhibited bladder cancer cells proliferation and promoted apoptosis, and miR‐21 had the opposite effects. MiR‐21 was a direct target for GAS5, whereas phosphatase and tensin homolog (PTEN) was a direct target gene of miR‐21. Low expression of miR‐21 could reverse the proliferative and antiapoptotic effects caused by GAS5 silencing. High levels of GAS5 and low levels of miR‐21 might be associated with a higher survival rate in bladder cancer patients. GAS5 could exert antiproliferative and proapoptotic effects on bladder cancer cells through miR‐21 and PTEN.

Dysregulated MicroRNA Fingerprints and Methylation Patterns in Hepatocellular Carcinoma, Cancer Stem Cells, and Mesenchymal Stem Cells

Hepatocellular carcinoma (HCC) is one of the top causes of cancer mortality worldwide. Although HCC has been researched extensively, there is still a need for novel and effective therapeutic interventions. There is substantial evidence that initiation of carcinogenesis in liver cirrhosis, a leading cause of HCC, is mediated by cancer stem cells (CSCs). CSCs were also shown to be responsible for relapse and chemoresistance in several cancers, including HCC. MicroRNAs (miRNAs) constitute important epigenetic markers that regulate carcinogenesis by acting post-transcriptionally on mRNAs, contributing to the progression of HCC. We have previously shown that co-culture of cancer cells with mesenchymal stem cells (MSCs) could induce the reprogramming of MSCs into CSC-like cells. In this review, we evaluate the available data concerning the epigenetic regulation of miRNAs through methylation and the possible role of this regulation in stem cell and somatic reprogramming in HCC.

A combined treatment of curcumin, piperine, and taurine alters the circulating levels of IL-10 and miR-21 in hepatocellular carcinoma patients: a pilot study

Background

Investigating and evaluating possible alternative therapeutic strategies to control hepatocellular carcinoma (HCC) is a critical need because of its high prevalence and being one of the most lethal cancers. Curcumin and taurine showed potent anti-tumor activities in pre-clinical and clinical studies by targeting multiple pathways. Thus, this study was designed to assess the effect of a combined treatment consisted of curcumin, piperine, and taurine on circulating levels of interleukin-10 (IL-10), and microRNAs miR-141 and miR-21.

Methods

Twenty eligible HCC patients administrated an oral dose of 4 g curcumin, 40 mg piperine, and 500 mg taurine daily for three successive treatment cycles, each was a 30-day. The level of IL-10 along with the expression levels of miR-141, and miR-21 were monitored in serum before starting the treatment and after each cycle. Patients were followed-up for a period of 24 months.

Results

The combined treatment was able to produce a significant decrease in the levels of serum IL-10, and miR-21 while it resulted in a non-significant up-regulation of serum miR-141 expression level. At the end of the follow-up period, the median overall survival (OS) rate was found to be 17.00 months with a worse OS in patients with high baseline levels of circulating IL-10 and miR-21 compared to those with low levels. In contrast, a low baseline level of circulating miR-141 was associated with poor prognosis.

Conclusions

The combined treatment may be able to increase the OS rate by altering the circulating level of IL-10 and miR-21.

Diagnostic and prognostic biomarkers in cholangiocarcinoma

The high mortality rate of cholangiocarcinoma (CCA) is due, in part, to the lack of non-invasive approaches able to accurately detect this silent tumour at early stages, when therapeutic options can be potentially curative or may at least increase the overall survival of patients. The fact that the majority of CCA tumours are not linked to any known aetiological factor highly compromises the monitoring of patients at risk for tumour development and also their early diagnosis. Combination of clinical/biochemical features, imaging techniques and analysis of non-specific tumour biomarkers in serum are commonly used to help in the diagnosis of CCA, but tumour biopsy is usually required to confirm the diagnosis. Moreover, no prognostic biomarkers are currently used in the clinical setting, deserving more innovative research, and international validation and consensus. Important efforts have been made in the last few years to identify accurate non-invasive biomarkers, by using innovative techniques and high-throughput omics technologies. This review summarizes and discusses the advances in the investigation of novel diagnostic and prognostic biomarkers in CCA and envisions the future directions in this field of research.

Inflammation and Liver Cancer: Molecular Mechanisms and Therapeutic Targets

Hepatocellular carcinoma (HCC) is associated with chronic inflammation and fibrosis arising from different etiologies, including hepatitis B and C and alcoholic and nonalcoholic fatty liver diseases. The inflammatory cytokines tumor necrosis factor-α and interleukin-6 and their downstream targets nuclear factor kappa B (NF-κB), c-Jun N-terminal kinase (JNK), and signal transducer and activator of transcription 3 drive inflammation-associated HCC. Further, while adaptive immunity promotes immune surveillance to eradicate early HCC, adaptive immune cells, such as CD8+ T cells, Th17 cells, and B cells, can also stimulate HCC development. Thus, the role of the hepatic immune system in HCC development is a highly complex topic. This review highlights the role of cytokine signals, NF-κB, JNK, innate and adaptive immunity, and hepatic stellate cells in HCC and discusses whether these pathways could be therapeutic targets. The authors will also discuss cholangiocarcinoma and liver metastasis because biliary inflammation and tumor-associated stroma are essential for cholangiocarcinoma development and because primary tumor-derived inflammatory mediators promote the formation of a "premetastasis niche" in the liver.

miR-21 promotes cell migration and invasion of hepatocellular carcinoma by targeting KLF5

Previous studies have reported that microRNAs regulate gene expression and transcription. miR-21 have been identified to play a role in many types of cancer. KLF5 functions as a tumor inhibitor in certain cancers. However, the role of KLF5 plays in hepatocellular carcinoma (HCC), especially concerning the relationship between miR-21 and the KLF5 gene remains to be determined. Reverse transcription-quantitative PCR (RT-qPCR), western blot analysis, as well as luciferase reporter and Transwell assays were used to determine the expression of miR-21 and KLF5 in Huh 7, SK-HEP-1, LO-2, and HCC tissues. In HCC cells and tissues, the upregulation of miR-21 was identified. HCC cell migratory and invasive abilities significantly increased because of miR-21 overexpression. KLF5 expression was inhibited by miR-21 by targeting its 3′-UTR. KLF5 overexpression alleviated the effect induced by miR-21 on the migratory and invasive ability of the Huh 7 cells. The results therefore show that, HCC cell migration and invasion is significantly suppressed by miR-21 via targeting KLF5. The newly identified miR-21/KLF5 axis provides a useful therapeutic biomarker for HCC treatment.

Overview upon miR-21 in lung cancer: focus on NSCLC

Considering the high mortality rate encountered in lung cancer, there is a strong need to explore new biomarkers for early diagnosis and also improved therapeutic targets to overcome this issue. The implementation of microRNAs as important regulators in cancer and other pathologies expanded the possibilities of lung cancer management and not only. MiR-21 represents an intensively studied microRNA in many types of cancer, including non-small cell lung cancer (NSCLC). Its role as an oncogene is underlined in multiple studies reporting the upregulated expression of this sequence in patients diagnosed with this malignancy; moreover, several studies associated this increased expression of miR-21 with a worse outcome within NSCLC patients. The same pattern is supported by the data existent in the Cancer Genome Atlas (TCGA). The carcinogenic advantage generated by miR-21 in NSCLC resides in the target genes involved in multiple pathways such as cell growth and proliferation, angiogenesis, invasion and metastasis, but also chemo- and radioresistance. Therapeutic modulation of miR-21 by use of antisense sequences entrapped in different delivery systems has shown promising results in impairment of NSCLC. Hereby, we review the mechanisms of action of miR-21 in cancer and the associated changes upon tumor cells together a focused perspective on NSCLC signaling, prognosis and therapy.

Prospects of Noncoding RNAs in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a global health problem and one of the most common malignant tumors. Recent studies have shown that noncoding RNAs (ncRNAs) contribute to the pathogenesis of hepatocellular carcinoma (HCC). These RNAs may be involved in a variety of pathological processes such as cell proliferation, apoptosis, angiogenesis, invasion, and metastasis. In addition, abnormal expression of ncRNAs in HCC may provide potential prognostic or diagnostic biomarkers. This review provides an overview of the role and potential applications of ncRNAs, miRNAs, lncRNAs, circRNAs, and snoRNAs in liver cancer.

High expression of miR-21 is not a predictor of poor prognosis in all patients with hepatocellular carcinoma

MicroRNA (miR)-21 has been identified as a novel biomarker of hepatocellular carcinoma (HCC). However, the prognostic value of miR-21 expression in HCC remains controversial. The aim of the present study was to investigate the value of high expression of miR-21 in predicting the prognosis of HCC. Following a search through the PubMed, Science Citation Index, EMBASE and CNKI databases, a total of 9 studies investigating the expression of miR-21 in HCC and the association between high expression of miR-21 and prognosis of HCC were identified. It was observed that high expression of miR-21 was not associated with poor overall survival of all patients with HCC (P=0.52). However, high expression of miR-21 was found to be correlated with poor prognosis of HCC patients undergoing curative resection (hazard ratio = 2.36; P<0.01). It was also demonstrated that high expression of miR-21 was correlated with tumor size >5 cm [odds ratio (OR)=1.53; P=0.04], venous invasion (OR=4.86; P=0.01), TNM stage (OR=3.44; P<0.01) and liver cirrhosis (OR=2.12; P=0.03). It was concluded that miR-21 cannot be considered as a factor complementary to α-fetoprotein, microvascular invasion and advanced tumor stage in predicting the prognosis of all HCC patients. Higher expression of miR-21 may be a promising biomarker associated with certain clinicopathological characteristics of HCC, such as tumor size, venous invasion, TNM stage and liver cirrhosis.

A Comprehensive Analysis of Argonaute-CLIP Data Identifies Novel, Conserved and Species-Specific Targets of miR-21 in Human Liver and Hepatocellular Carcinoma

MicroRNAs are ~22 nucleotide RNAs that regulate gene expression at the post-transcriptional level by binding messenger RNA transcripts. miR-21 is described as an oncomiR whose steady-state levels are commonly increased in many malignancies, including hepatocellular carcinoma (HCC). Methods known as cross-linking and immunoprecipitation of RNA followed by sequencing (CLIP-seq) have enabled transcriptome-wide identification of miRNA interactomes. In our study, we use a publicly available Argonaute-CLIP dataset (GSE97061), which contains nine HCC cases with matched benign livers, to characterize the miR-21 interactome in HCC. Argonaute-CLIP identified 580 miR-21 bound target sites on coding transcripts, of which 332 were located in the coding sequences, 214 in the 3'-untranslated region, and 34 in the 5'-untranslated region, introns, or downstream sequences. We compared the expression of miR-21 targets in 377 patients with liver cancer from the data generated by The Cancer Genome Atlas (TCGA) and found that mRNA levels of 402 miR-21 targets are altered in HCC. Expression of three novel predicted miR-21 targets (CAMSAP1, DDX1 and MARCKSL1) correlated with HCC patient survival. Analysis of RNA-seq data from SK-Hep1 cells treated with a miR-21 antisense oligonucleotide (GSE65892) identified RMND5A, an E3 ubiquitin ligase, as a strong miR-21 candidate target. Collectively, our analysis identified novel miR-21 targets that are likely to play a causal role in hepatocarcinogenesis.

Prognostic value of microRNAs in hepatocellular carcinoma: a meta-analysis

Background

Numerous articles reported that dysregulated expression levels of miRNAs correlated with survival time of HCC patients. However, there has not been a comprehensive meta-analysis to evaluate the accurate prognostic value of miRNAs in HCC.

Design

Meta-analysis.

Materials and Methods

Studies, published in English, estimating expression levels of miRNAs with any survival curves in HCC were identified up until 15 April, 2017 by performing online searches in PubMed, EMBASE, Web of Science and Cochrane Database of Systematic Reviews by two independent authors. The pooled hazard ratios (HR) with 95% confidence intervals (CI) were used to estimate the correlation between miRNA expression and overall survival (OS).

Results

54 relevant articles about 16 miRNAs, with 6464 patients, were ultimately included. HCC patients with high expression of tissue miR-9 (HR = 2.35, 95% CI = 1.46–3.76), miR-21 (HR = 1.76, 95% CI = 1.29–2.41), miR-34c (HR = 1.64, 95% CI = 1.05–2.57), miR-155 (HR = 2.84, 95% CI = 1.46–5.51), miR-221 (HR = 1.76, 95% CI = 1.02–3.04) or low expression of tissue miR-22 (HR = 2.29, 95% CI = 1.63–3.21), miR-29c (HR = 1.35, 95% CI = 1.10–1.65), miR-34a (HR = 1.84, 95% CI = 1.30–2.59), miR-199a (HR = 2.78, 95% CI = 1.89–4.08), miR-200a (HR = 2.64, 95% CI = 1.86–3.77), miR-203 (HR = 2.20, 95% CI = 1.61–3.00) have significantly poor OS (P < 0.05). Likewise, HCC patients with high expression of blood miR-21 (HR = 1.73, 95% CI = 1.07–2.80), miR-192 (HR = 2.42, 95% CI = 1.15–5.10), miR-224 (HR = 1.56, 95% CI = 1.14–2.12) or low expression of blood miR-148a (HR = 2.26, 95% CI = 1.11–4.59) have significantly short OS (P < 0.05).

Conclusions

In conclusion, tissue miR-9, miR-21, miR-22, miR-29c, miR-34a, miR-34c, miR-155, miR-199a, miR-200a, miR-203, miR-221 and blood miR-21, miR-148a, miR-192, miR-224 demonstrate significantly prognostic value. Among them, tissue miR-9, miR-22, miR-155, miR-199a, miR-200a, miR-203 and blood miR-148a, miR-192 are potential prognostic candidates for predicting OS in HCC.

Argonaute CLIP Defines a Deregulated miR-122-Bound Transcriptome that Correlates with Patient Survival in Human Liver Cancer

MicroRNA-122, an abundant and conserved liver-specific miRNA, regulates hepatic metabolism and functions as a tumor suppressor, yet systematic and direct biochemical elucidation of the miR-122 target network remains incomplete. To this end, we performed Argonaute crosslinking immunoprecipitation (Argonaute [Ago]-CLIP) sequencing in miR-122 knockout and control mouse livers, as well as in matched human hepatocellular carcinoma (HCC) and benign liver tissue to identify miRNA target sites transcriptome-wide in two species. We observed a majority of miR-122 binding on 3' UTRs and coding exons followed by extensive binding to other genic and non-genic sites. Motif analysis of miR-122-dependent binding revealed a G-bulged motif in addition to canonical motifs. A large number of miR-122 targets were found to be species specific. Upregulation of several common mouse and human targets, most notably BCL9, predicted survival in HCC patients. These results broadly define the molecular consequences of miR-122 downregulation in hepatocellular carcinoma.

Downregulation of PDCD4 by miR-21 suppresses tumor transformation and proliferation in a nude mouse renal cancer model

Programmed cell death 4 (PDCD4) is known to suppress neoplastic transformation, cell proliferation and metastasis, and to be downregulated by microRNA-21 (miR-21) in renal cell carcinoma (RCC) cell lines and tissues. The aim of the present study was to investigate the roles of and association between PDCD4 and miR-21 in a nude mouse renal cancer model. A total of 24 BALB/c male nude mice were randomly assigned into the following three groups: Negative control (NC; n=8), miR-21 inhibitor (n=8) and miR-21 mimic (n=8). Subsequently, renal cell adenocarcinoma 786-O cells were subcutaneously transplanted into the armpits of the mice, which were then injected daily with NC small interfering (si)RNA, precursor-miR-21 (mimic) or anti-miR-21 (inhibitor). Tumors were removed from the mice and weighed 16 days following 786-O cell transplantation. In addition, the expression of miR-21 and PDCD4 mRNA in cancer tissues was analyzed using reverse transcription-quantitative PCR. The expression of PDCD4 protein in cancer tissues was also examined using immunohistochemistry and western blotting. Furthermore, 786-O cells were transfected with PDCD4 siRNA or NC siRNA, and the effects of silencing PDCD4 on tumor cell growth, proliferation and invasion were investigated using soft agar colony formation, EdU cell proliferation assay and Transwell migration and invasion assays. Another 16 BALB/c male nude mice were randomly assigned into two groups as follows: NC (n=8) and PDCD4 siRNA (n=8). The 786-O cells were subcutaneously transplanted into the armpits of the mice, which were subsequently injected daily with NC siRNA or PDCD4 siRNA. The tumors were removed and weighed 16 days following transplantation. Compared with the NC group, tumor weight in the miR-21 mimic group was significantly increased. By contrast, tumor weight in the miR-21 inhibitor group was significantly decreased. Similar to the results observed in human renal cancer tissue and cell lines, miR-21 expression in the nude mouse renal cancer models was significantly upregulated in the miR-21 mimic group compared with the NC group, while it was significantly lower in the miR-21 inhibitor group. Furthermore, there was a significant reduction in PDCD4 protein levels in the miR-21 mimic group and a significant increase in the miR-21 inhibitor group compared with the NC, whereas PDCD4 mRNA expression was not significantly altered. In the EdU proliferation assay, the mean percentage of new cells that incorporated EdU was 28.6% in the NC siRNA group and significantly increased to 44.7% in PDCD4 siRNA transfected cells. In the soft agar colony formation assay, Transwell and migration and invasion assays, a significant increase in colony formation, migration and invasion capacity in PDCD4 siRNA-transfected cells was observed compared with the NC. Furthermore, compared with the NC group, tumor weight in the PDCD4 siRNA group was significantly increased. Similar to the results observed in human renal cancer tissue and cell lines, miR-21 promoted cancer cell hyperplasia and proliferation, and post-transcriptionally downregulated PDCD4 protein expression, in the nude mouse renal cancer model. The results of the present study and previous studies indicate that PDCD4 and miR-21 serve an important role in renal cancer. Thus, increasing PDCD4 expression or inhibiting miR-21 expression may constitute effective novel therapeutic strategies for the treatment of renal cancer.

Biomarker MicroRNAs for Diagnosis, Prognosis and Treatment of Hepatocellular Carcinoma: A Functional Survey and Comparison

Hepatocellular Carcinoma (HCC) is one of the most common malignant tumors with high incidence and mortality rate. Precision and effective biomarkers are therefore urgently needed for the early diagnosis and prognostic estimation. MicroRNAs (miRNAs) are important regulators which play functions in various cellular processes and biological activities. Accumulating evidence indicated that the abnormal expression of miRNAs are closely associated with HCC initiation and progression. Recently, many biomarker miRNAs for HCC have been identified from blood or tissues samples, however, the universality and specificity on clinicopathological features of them are less investigated. In this review, we comprehensively surveyed and compared the diagnostic, prognostic, and therapeutic roles of HCC biomarker miRNAs in blood and tissues based on the cancer hallmarks, etiological factors as well as ethnic groups, which will be helpful to the understanding of the pathogenesis of biomarker miRNAs in HCC development and further provide accurate clinical decisions for HCC diagnosis and treatment.

Stratification of Digestive Cancers with Different Pathological Features and Survival Outcomes by MicroRNA Expression

MicroRNAs (miRNAs) are aberrantly expressed in virtually all cancer types, including digestive cancers. Herein, we aggregated and systematically analyzed miRNA expression profiles of 1765 tumor samples, including esophageal, gastric, liver, pancreatic, colon and rectal cancers, obtained through small RNA sequencing by The Cancer Genome Atlas. We found that digestive cancers of different tissue origins could be differentiated according to their miRNA expression profiles. In particular, esophageal squamous cell carcinoma and esophageal adenocarcinoma exhibited distinct miRNA expression patterns. Thirteen (e.g. miR-135b, miR-182) and sixteen (e.g. miR-139, miR-133a-1, miR-490) miRNAs were commonly upregulated and downregulated in more than four cancer types, respectively. Pertinent to pathological features, low miR-181d expression was associated with microsatellite instability in colon and gastric cancers whereas low miR-106a expression was associated with hepatitis B virus infection in hepatocellular carcinoma. Progression in colon cancer could also be predicted by low let-7f-2 and high miR-106a expression. Molecular subtypes with distinct prognostic outcomes independent of tumor-node-metastasis staging were identified in hepatocellular carcinoma and colon cancer. In total, 4 novel and 6 reported associations between specific miRNAs and patients’ survival were identified. Collectively, novel miRNA markers were identified to stratify digestive cancers with different pathological features and survival outcomes.

Long noncoding RNA GAS5 suppresses the migration and invasion of hepatocellular carcinoma cells via miR-21

Long noncoding RNAs (lncRNAs) are aberrantly expressed in various cancers. Although lncRNA GAS5 (growth arrest-specific transcript 5) has been characterized as a tumor suppressor in some kinds of cancer, its role and function in hepatocellular carcinoma (HCC) remain unknown. The present report demonstrates that there are lower levels of GAS5, PDCD4, and PTEN and higher levels of microRNA-21 (miR-21) in HCC tissues than in adjacent normal tissues. Moreover, the levels of GAS5 and miR-21 were correlated with the clinicopathological characteristics of HCC. HCC patients with higher levels of GAS5 or with the lower levels of miR-21 have longer survival times. There are lower levels of GAS5 and higher levels of miR-21 in HCC cell lines (Be7402, SMMC-7721, and HCCLM3) than in normal liver L-02 cells, and the levels correlate with the aggression of the HCC cell lines. Knockdown of GAS5 upregulates miR-21 levels in Bel-7402 cells (weakly aggressive); in contrast, there are opposite changes in HCCLM3 cells (highly aggressive). Moreover, GAS5 that upregulated or downregulated the expression of PDCD4 and PTEN was reversed by inhibiting or overexpressing miR-21 level in Bel-7402 and HCCLM3 cells. Then, overexpression of GAS5 suppresses the migration and invasion of HCC cells and high expression of miR-21 largely eliminates GAS5-mediated suppression of HCC cell migration and invasion. Thus, GAS5 acts as a tumor suppressor in HCCs through negative regulation of miR-21 and its targets and proteins about migration and invasion in cancer cells, which may be a target for treating HCC.

Hepatitis B Virus Infection, MicroRNAs and Liver Disease

Hepatitis B virus (HBV) attacks the liver and can cause both acute as well as chronic liver diseases which might lead to liver cirrhosis and hepatocellular carcinoma. Regardless of the availability of a vaccine and numerous treatment options, HBV is a major cause of morbidity and mortality across the world. Recently, microRNAs (miRNAs) have emerged as important modulators of gene function. Studies on the role of miRNA in the regulation of hepatitis B virus gene expression have been the focus of modern antiviral research. miRNAs can regulate viral replication and pathogenesis in a number of different ways, which includefacilitation, direct or indirect inhibition, activation of immune response, epigenetic modulation, etc. Nevertheless, these mechanisms can appropriately be used with a diagnosticand/or therapeutic approach. The present review is an attempt to classify specific miRNAs that are reported to be associated with various aspects of hepatitis B biology, in order to precisely present the participation of individual miRNAs in multiple aspects relating to HBV.

Anti-miR-21 Suppresses Hepatocellular Carcinoma Growth via Broad Transcriptional Network Deregulation

Hepatocellular carcinoma (HCC) remains a significant clinical challenge with few therapeutic options available to cancer patients. MicroRNA 21-5p (miR-21) has been shown to be upregulated in HCC, but the contribution of this oncomiR to the maintenance of tumorigenic phenotype in liver cancer remains poorly understood. We have developed potent and specific single-stranded oligonucleotide inhibitors of miR-21 (anti-miRNAs) and used them to interrogate dependency on miR-21 in a panel of liver cancer cell lines. Treatment with anti-miR-21, but not with a mismatch control anti-miRNA, resulted in significant derepression of direct targets of miR-21 and led to loss of viability in the majority of HCC cell lines tested. Robust induction of caspase activity, apoptosis, and necrosis was noted in anti-miR-21-treated HCC cells. Furthermore, ablation of miR-21 activity resulted in inhibition of HCC cell migration and suppression of clonogenic growth. To better understand the consequences of miR-21 suppression, global gene expression profiling was performed on anti-miR-21-treated liver cancer cells, which revealed striking enrichment in miR-21 target genes and deregulation of multiple growth-promoting pathways. Finally, in vivo dependency on miR-21 was observed in two separate HCC tumor xenograft models. In summary, these data establish a clear role for miR-21 in the maintenance of tumorigenic phenotype in HCC in vitro and in vivo.

IMPLICATIONS

miR-21 is important for the maintenance of the tumorigenic phenotype of HCC and represents a target for pharmacologic intervention.