The role of microRNAs in the management of liver cancer

The role of microRNAs in the different phases of liver regeneration

INTRODUCTION

Since the first discovery of microRNAs (miRs) extensive evidence reveals their indispensable role in different patho-physiological processes. They are recognized as critical regulators of hepatic regeneration, as they modulate multiple complex signaling pathways affecting liver regeneration. MiR-related translational suppression and degradation of target mRNAs and proteins are not limited to one specific gene, but act on multiple targets.

AREAS COVERED

In this review, we are going to explore the role of miRs in the context of liver regeneration and discuss the regulatory effects attributed to specific miRs. Moreover, specific pathways crucial for liver regeneration will be discussed, with a particular emphasis on the involvement of miRs within the respective signaling cascades.

EXPERT OPINION

The considerable amount of studies exploring miR functions in a variety of diseases paved the way for the development of miR-directed therapeutics. Clinical implementation has already shown promising results, but additional research is warranted to assure safe and efficient delivery. Nevertheless, given the broad functional properties of miRs and their critical involvement during hepatic regeneration, they represent an attractive treatment target to promote liver recovery after hepatic resection.

Rosmarinic acid inhibits migration, invasion, and p38/AP-1 signaling via miR-1225-5p in colorectal cancer cells

Elucidating the molecular mechanism of the migration and invasion is critical for identifying novel therapeutic targets and may significantly improve the prognosis of colorectal cancer. Emerging evidence suggests an involvement of dysregulated microRNAs in the process of tumorigenesis. Here, we show that miR-1225-5p prevents migration and invasion of colorectal cancer cells. Overexpression of miR-1225-5p significantly decreases the expression of Matrix Metalloproteases (MMPs)-1, 3, and 9. Knockdown of miR-1225-5p elevates ROS level via regulating Keap1/Nrf2 pathway. Furthermore, miR-1225-5p attenuates IL-17A-induced p38/AP-1-signaling pathway by suppressing IL-17RA expression. We also examined the biological effects of Rosmarinic acid (RA) on metastatic colorectal cancer cells. RA inhibited EMT via the p38/AP-1 signaling, and miR-1225-5p is essential for RA-mediated anti-metastatic effects.

A Computational Approach to Identify Novel Potential Precursor miRNAs and their Targets from Hepatocellular Carcinoma Cells

Background:

Recent advances in next-generation sequencing technology allow highthroughput RNA-Sequencing to be widely applied in studying coding and non-coding RNA profiling in cells. RNA-Seq data usually contains functional transcriptomic and other small and larger non-coding (nc) RNA sequences. </P><P> Objective: MicroRNAs (miRNAs), a small nc-RNA act as epigenetic markers and the expression of their target genes and pathways that regulate Hepatocellular Carcinoma (HCC), a primary malignancy of the liver. The unreported potential novel miRNAs targeting HCC pathways can be identified from the sequenced data.

Methods:

In this study, we performed a computational identification of novel putative miRNAs and their targets from publicly available high-throughput sequencing Fastq data of human HCC cells HepG2, NorHep and SKHep1, retrieved from NCBI-SRA.

Results:

Totally, 572 unique known precursor miRNAs and 1062 unique novel miRNAs were identified from HepG2, Nor and SKHep1 HCC cell lines. Interestingly, 140 novel miRNAs were predicted to be extensively involved in targeting genes of HCC related pathways such as apoptosis, cell signaling, cell division, cell-cycle arrest, GPCR, MAPK cascade, TOR signaling, TNFSF11 signaling and liver development.

Conclusion:

The predicted novel miRNAs reported in the paper might have a vital role in regulating the molecular mechanism of HCC and thus, further studies on these miRNAs will provide significant clues for researchers into the complex biological process of liver cancer.

Predictive Value of MiR-219-1, MiR-938, MiR-34b/c, and MiR-218 Polymorphisms for Gastric Cancer Susceptibility and Prognosis

Gastric cancer (GC) is one of the most prominent global cancer-related health threats. Genes play a key role in the precise mechanisms of gastric cancer. SNPs in mi-RNAs could affect mRNA expression and then affect the risk and prognosis of GC. Firstly, we have decided to perform a case-control study which included 897 GC patients and 992 controls to evaluate the association of miR-219-1 rs213210, miR-938 rs2505901, miR-34b/c rs4938723, and miR-218 rs11134527 polymorphisms with gastric cancer susceptibility. Secondly, among the 897 GC patients above, 755 cases underwent a radical operation, without distant metastasis and with negative surgical margins included in the survival analysis to evaluate the association of the four SNPs above with gastric cancer prognosis. The C/T or C/C genotypes of rs213210 were related to a lower GC risk (OR = 0.76, 95% CI: 0.62–0.93, P = 0.009) compared to the T/T genotype. Rs11134527 in miR-218 was associated with GC survival, and the G/A and G/G genotypes of rs11134527 resulted in a decreased risk of death when compared with the A/A genotype (HR = 0.75, 95% CI: 0.61–0.95, P = 0.016). This study found that miR-219-1 rs213210 polymorphism was associated with GC susceptibility and rs11134527 in miR-218 was positively correlated with GC prognosis.

Role of Epigenetics in Uveal Melanoma

Uveal melanoma (UM) is a severe human malignancy with a high mortality rate that demands continued research into new and alternative forms of prevention and treatment. The emerging field of epigenetics is beginning to unfold an era of contemporary approaches to reducing the risk and improving the clinical treatment of UM. Epigenetic changes have a high prevalence rate in cancer, are reversible in nature, and can lead to cancer characteristics even in mutation-free cells. The information contained in this review highlights and expands on the main mechanisms of epigenetic dysregulation in UM tumorigenesis, progression and metastasis, including microRNA expression, hypermethylation of genes and histone modification. Epigenetic drugs have been shown to enhance tumor suppressor gene expression and drug sensitivity in many other cancer cell lines and animal models. An increased understanding of epigenetic mechanisms in UM will be invaluable in the design of more potent epigenetic drugs, which when used in combination with traditional therapies, may permit improved therapeutic outcomes.

Epigenetic biomarkers in liver cancer

Liver cancer (hepatocellular carcinoma or HCC) is a major cancer worldwide. Research in this field is needed to identify biomarkers that can be used for early detection of the disease as well as new approaches to its treatment. Epigenetic biomarkers provide an opportunity to understand liver cancer etiology and evaluate novel epigenetic inhibitors for treatment. Traditionally, liver cirrhosis, proteomic biomarkers, and the presence of hepatitis viruses have been used for the detection and diagnosis of liver cancer. Promising results from microRNA (miRNA) profiling and hypermethylation of selected genes have raised hopes of identifying new biomarkers. Some of these epigenetic biomarkers may be useful in risk assessment and for screening populations to identify who is likely to develop cancer. Challenges and opportunities in the field are discussed in this chapter.

miR-34a inhibits the migration and invasion of esophageal squamous cell carcinoma by targeting Yin Yang-1

Esophageal squamous cell carcinoma (ESCC), one of the most common gastrointestinal tumors, is known for its high mortality rate. microRNAs (miRNAs) have been reported to play important regulatory roles in cancer metastasis and progression. miR-34a has been demonstrated to be associated with the development of and metastasis in certain types of cancer via various target genes, but its function and targets in ESCC are unknown. The aim of this study was to examine whether the expression of miR-34a was significantly decreased in ESCC tissues, compared with normal esophageal tissues using RT-PCR and western blot analysis. The results showed that miR-34a overexpression increased apoptosis and decreased clonogenic formation, but inhibited invasion and migration in ESCC cells by suppressing MMP-2 and -9 expression. Yin Yang-1 (YY1), a widely distributed transcription factor that belongs to the GLI-Kruppel class of zinc finger proteins, was found to be a direct target of miR-34a in ESCC cell lines. Rescue experiments indicated that the suppressive effect of miR-34a on invasion and migration was mediated by activating YY1 expression. Results of the present study showed that miR-34a is associated with ESCC migration and provides a potential therapeutic and diagnostic target for ESCC.

MicroRNA-93 regulates collagen loss by targeting MMP3 in human nucleus pulposus cells

OBJECTIVES

Degenerated disc disease is one of the most common medical conditions in patients suffering from low back pain. Recent studies have shown that microRNAs can regulate cell function in many pathological conditions. The aim of this study was to investigate expression and role of miR-93 in disc degeneration.

MATERIALS AND METHODS

Quantitative RT-PCR was employed to investigate level of miR-93 in degenerative nucleus pulposus (NP) tissues. Then, functional analysis of miR-93 in regulating collagen II expression was performed. Subsequently, western blotting and luciferase reporter assay were used to detect the target gene.

RESULTS

We showed that miR-93 was significantly down-regulated in degenerative NP tissues and its levels were associated with grade of disc degeneration. Overexpression of miR-93 stimulated type II collagen expression in NP cells. Moreover, MMP3 was identified as a putative target of miR-93. MiR-93 inhibited MMP3 expression by directly targeting its 3'UTR, and this was abolished by miR-93 binding site mutations. Additionally, restoration of MMP3 in miR-93-overexpressed NP cells reversed effects of type II collagen expression. Expression of MMP3 inversely correlated with miR-93 expression in degenerative NP tissues.

CONCLUSIONS

Taken together, we demonstrated that miR-93 contributed to abnormal NP cell type II collagen expression by targeting MMP3, involved in intervertebral disc degeneration.

MicroRNA dysregulation in uveal melanoma: a new player enters the game

Uveal melanoma is the second most common form of melanoma and a predominant intraocular malignant tumor in adults. The development of uveal melanoma is a multistep process involving genetic and epigenetic alteration of proto-oncogenes and tumor-suppressor genes. Recent discoveries have shed a new light on the involvement of a class of noncoding RNA known as microRNAs (miRNAs) in uveal melanoma. A lot of miRNAs show differential expressions in uveal melanoma tissues and cell lines. Genes coding for these miRNAs have been characterized as novel oncogene and tumor-suppressor genes based on findings that these miRNAs control malignant phenotypes of uveal melanoma cells. Several studies have confirmed that dysregulation of miRNAs promotes cell-cycle progression, confers resistance to apoptosis, and enhances invasiveness and metastasis. Moreover, several miRNAs have also been shown to correlate with uveal melanoma initiation and progression, and thus may be used as biomarkers for early diagnosis and prognosis. Elucidating the biological aspects of miRNA dysregulation may help us better understand the pathogenesis of uveal melanoma and promote the development of miRNA directed-therapeutics against this disease.

MicroRNAs: the fine modulators of liver development and function

MicroRNAs are a class of small non-coding RNAs involved in the transcriptional and post-transcriptional regulation of gene expression. The function of miRNAs in liver disease including hepatocellular carcinoma (HCC), hepatitis, and alcoholic liver disease, have been widely studied and extensively reviewed. Increasing evidence demonstrates that miRNAs also play a critical role in normal liver development and in the fine-tuning of fundamental biological liver processes. In this review, we highlight the most recent findings on the role of miRNAs in liver specification and differentiation, liver cell development, as well as in the many metabolic functions of the liver, including glucose, lipid, iron and drug metabolism. These findings demonstrate an important role of miRNAs in normal liver development and function. Further researches will be needed to fully understand how miRNAs regulate liver generation and metabolic function, which should then lead to greater insights in liver biology and perhaps open up the possibility to correct errors that cause liver diseases or metabolic disorders.

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

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

Downregulation of miR-16 promotes growth and motility by targeting HDGF in non-small cell lung cancer cells

MicroRNAs play important roles in the development and progression of non-small cell lung cancer (NSCLC). miR-16 functions as a tumor-suppressor and is inhibited in several malignancies. Herein, we validated that miR-16 is downregulated in NSCLC tissue samples and cell lines. Ectopic expression of miR-16 significantly inhibited cell proliferation and colony formation. Moreover, miR-16 suppressed cell migration and invasion in NSCLC cells. Hepatoma-derived growth factor (HDGF) was found to be a direct target of miR-16 in NSCLC cell lines. Rescue experiments showed that the suppressive effect of miR-16 on cell proliferation, colony formation, migration, and invasion is partially mediated by inhibiting HDGF expression. This study indicates that miR-16 might be associated with NSCLC progression, and suggests an essential role for miR-16 in NSCLC.