Exosomal miR-638 Inhibits Hepatocellular Carcinoma Progression by Targeting SP1

An Insight into the Arising Role of MicroRNAs in Hepatocellular Carcinoma: Future Diagnostic and Therapeutic Approaches

Hepatocellular carcinoma (HCC) constitutes a frequent highly malignant form of primary liver cancer and is the third cause of death attributable to malignancy. Despite the improvement in the therapeutic strategies with the exploration of novel pharmacological agents, the survival rate for HCC is still low. Shedding light on the multiplex genetic and epigenetic background of HCC, such as on the emerging role of microRNAs, is considered quite promising for the diagnosis and the prediction of this malignancy, as well as for combatting drug resistance. MicroRNAs (miRNAs) constitute small noncoding RNA sequences, which play a key role in the regulation of several signaling and metabolic pathways, as well as of pivotal cellular functions such as autophagy, apoptosis, and cell proliferation. It is also demonstrated that miRNAs are significantly implicated in carcinogenesis, either acting as tumor suppressors or oncomiRs, while aberrations in their expression levels are closely associated with tumor growth and progression, as well as with local invasion and metastatic dissemination. The arising role of miRNAs in HCC is in the spotlight of the current scientific research, aiming at the development of novel therapeutic perspectives. In this review, we will shed light on the emerging role of miRNAs in HCC.

Natural Bioactive Compounds Targeting Histone Deacetylases in Human Cancers: Recent Updates

Cancer is a complex pathology that causes a large number of deaths worldwide. Several risk factors are involved in tumor transformation, including epigenetic factors. These factors are a set of changes that do not affect the DNA sequence, while modifying the gene’s expression. Histone modification is an essential mark in maintaining cellular memory and, therefore, loss of this mark can lead to tumor transformation. As these epigenetic changes are reversible, the use of molecules that can restore the functions of the enzymes responsible for the changes is therapeutically necessary. Natural molecules, mainly those isolated from medicinal plants, have demonstrated significant inhibitory properties against enzymes related to histone modifications, particularly histone deacetylases (HDACs). Flavonoids, terpenoids, phenolic acids, and alkaloids exert significant inhibitory effects against HDAC and exhibit promising epi-drug properties. This suggests that epi-drugs against HDAC could prevent and treat various human cancers. Accordingly, the present study aimed to evaluate the pharmacodynamic action of different natural compounds extracted from medicinal plants against the enzymatic activity of HDAC.

Exosomes in Pathogenesis, Diagnosis, and Treatment of Hepatocellular Carcinoma

Exosomes are extracellular vesicles with a diameter of 30-150 nm that are released by most types of cells and have been confirmed to be involved in many physical and pathological processes, especially in cell to cell communication. Compared with other vesicles, exosomes have a unique double-layer saclike structure that allows them to be present stably in various body fluids, including blood, cerebrospinal fluid, urine, saliva, and serous cavity effusion. The cargoes of exosomes reflect the characteristics of host cells. Due to the nature of hepatocellular carcinoma (HCC) cells, heterogeneity in the bioactive substances usually exist in exosomes. In addition, exosomes can efficiently deliver cargoes to the target cells to exert pathological functions, playing important role in tumor occurrence, development, metastasis, immune regulation, and drug resistance. Previous studies have been shown that exosomes have wide applications in diagnosis and treatment of HCC. In this review, we discuss these recent findings and highlight the significant roles of exosomes in HCC, focusing on the effect and underlying mechanisms of exosomes to regulate HCC progression and the potential clinical value of exosomes as biomarkers and therapeutic targets.

Long noncoding RNA NEAT1 changes exosome secretion and microRNA expression carried by exosomes in hepatocellular carcinoma cells

BACKGROUND

This study aimed to investigate the roles and functions of nuclear-enriched abundant transcript 1 (NEAT1) in exosome secretion and exosomal microRNA (miRNA) changes in hepatocellular carcinoma (HCC) cells.

METHODS

HepG2 and HuH-7 cells were divided into two groups: Lv-control (which were infected with lentivirus without NEAT1 expression) and Lv-NEAT1 (which were infected with lentivirus with NEAT1 overexpression). Each group was used to study cell function (proliferation, invasion, and apoptosis) and exosome secretion by nanoparticle tracking analysis (NTA), electron microscopy, and nanoflow cytometry (nanoFCM). Different levels of messenger RNA (mRNA), miRNA, and exosomal miRNA were detected by RNA sequencing. Next, potential target RNAs were verified by reverse transcription polymerase chain reaction (RT-PCR). Changed exosomal miRNAs were found and miRNA mimics were used to study cell function in NEAT1-overexpression and NEAT1-knockdown HCC cells.

RESULTS

The data showed that NEAT1-overexpression promoted exosome secretion. The overexpression of NEAT1 altered global genes, including exosome-related genes. Compared with the control group, we observed that several miRNAs changed in the exosomes secreted by NEAT1-overexpressing cells. Our study found that these changed exosomal miRNAs played a suppressor role in HCC. Transfection of miR-634, miR-638, and miR-3960 reversed the enhanced invasion and proliferation in HCC cells with a high level of NEAT1 expression.

CONCLUSIONS

These results suggested that NEAT1 regulates exosome-related genes, which might be associated with increasing exosome secretion by NEAT1-overexpressing cells. Furthermore, NEAT1 promotes cell invasion and proliferation via downregulation of miR-634, miR-638, and miR-3960 in exosomes. This study may provide potential targets for exosome-mediated miRNA transfer in HCCs with a high level of NEAT1 expression therapy.

Exosomal non-coding RNAs in Hepatobiliary Cancer: A Rising Star

Hepatobiliary cancers are a heterogeneous group of malignancies with a dismal prognosis. Despite intensive research efforts focused on these tumors, methods for early diagnosis and effective targeted therapies are still lacking. Exosomes, released by most cells, exist in all kinds of body fluids and play an important role in cell-to-cell communication. They are small membranous vesicles containing biological molecules, such as noncoding RNAs (ncRNAs), which are not translated into proteins, but they exert effects on the regulation of gene transcription and translation. There is growing evidence for the essential roles of ncRNAs in exosomes in both physiological and pathological conditions of hepatobiliary cancers. They have been identified as sensitive diagnostic biomarkers as well as potential therapeutic targets. The present review discusses recent findings in the crosstalk between hepatobiliary cancers cells and the surrounding cells of the microenvironment and discuss their potential clinical usage.

Exosomal microRNAs in hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common malignant tumors worldwide and the fourth leading cause of cancer-related deaths. The prognosis of hepatocellular carcinoma patients is extremely poor due to the occult onset and high metastasis of hepatocellular carcinoma. Therefore, biomarkers with high specificity and sensitivity are of great importance in early screening, diagnosis prognosis, and treatment of hepatocellular carcinoma patients. Exosomes are tiny vesicles secreted by various types of cells, which can serve as mediators of intercellular communication to regulate the tumor microenvironment, and play a key role in the occurrence, development, prognosis, monitor and treatment of hepatocellular carcinoma. As microRNA deliverer, exosomes are involved in multiple life activities by regulating target genes of recipient cells such as proliferation, invasion, metastasis and apoptosis of cancer cells. In this review, we summarized the composition, active mechanism and function of exosomal microRNAs in hepatocellular carcinoma, and elaborated on their potential application value of early diagnosis and treatment in hepatocellular carcinoma.

Prognostic and clinicopathological significance of miR-638 in cancer patients: A meta-analysis

INTRODUCTION

MiR-638 is believed to be involved in human cancers. However, the prognostic value of miR-638 in human carcinomas is controversial and inconclusive. Therefore, we conducted this meta-analysis to investigate the association between miR-638 expression and clinical outcomes in the patients with various cancers.

METHODS

We searched Pubmed, Embase, Wanfang, and the China National Knowledge Infrastructure (CNKI) up to September 1, 2020 to identify relevant studies. Hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were used to correlate expression of miR-638 with prognosis and clinicopathological features.

RESULTS

A total of 18 studies involving 1886 patients were included in the meta-analysis. The results revealed that low miR-638 expression was significantly correlated with poor overall survival (OS) (HR = 2.09, 95% CI: 1.46-2.98, P < .001), but not with disease-free survival (DFS) (HR = 1.71, 95% CI: 0.31-9.56, P = .540). Subgroup analysis found that low miR-638 expression was associated with worse OS in patients with digestive system cancer (HR = 2.47, 95% CI: 1.85-3.30, P < .001), the reported directly from articles group (HR = 2.12, 95% CI: 1.34-3.33, P < .001), survival curves group (HR = 2.02, 95% CI: 1.07-3.80, P = .029), in studies with sample size ≥100 (HR = 2.12, 95% CI: 1.34-3.35, P = .001), and in studies with sample size <100 (HR = 2.02, 95%CI: 1.09-3.75, P = .025). Moreover, cancer patients with low miR-638 expression were prone to tumor size (OR = 1.47, 95% CI: 1.03-2.09, P = .035), earlier lymph node metastasis (present vs absent, OR = 2.26, 95% CI: 1.63-3.14, P < .001), earlier distant metastasis (present vs absent, OR = 2.60, 95% CI: 1.45-4.67, P < .001), TNM stage (III-IV vs I-II, OR = 2.01, 95% CI: 1.35-2.99, P = .001), and portal vein invasion (present vs absent, OR = 4.39, 95% CI:2.23-8.64, P < .001), but not associated with age, gender, tumor differentiation, and vascular invasion.

CONCLUSIONS

MiR-638 may serve as a promising indicator in the prediction of prognosis and clinicopathological features in patients with different kinds of cancers.

Exosomal Non-Coding RNAs: Regulatory and Therapeutic Target of Hepatocellular Carcinoma

Exosomes are small extracellular vesicles secreted by most somatic cells, which can carry a variety of biologically active substances to participate in intercellular communication and regulate the pathophysiological process of recipient cells. Recent studies have confirmed that non-coding RNAs (ncRNAs) carried by tumor cell/non-tumor cell-derived exosomes have the function of regulating the cancerous derivation of target cells and remodeling the tumor microenvironment (TME). In addition, due to the unique low immunogenicity and high stability, exosomes can be used as natural vehicles for the delivery of therapeutic ncRNAs in vivo. This article aims to review the potential regulatory mechanism and the therapeutic value of exosomal ncRNAs in hepatocellular carcinoma (HCC), in order to provide promising targets for early diagnosis and precise therapy of HCC.

An integrated workflow for biomarker development using microRNAs in extracellular vesicles for cancer precision medicine

EV-miRNAs are microRNA (miRNA) molecules encapsulated in extracellular vesicles (EVs), which play crucial roles in tumor pathogenesis, progression, and metastasis. Recent studies about EV-miRNAs have gained novel insights into cancer biology and have demonstrated a great potential to develop novel liquid biopsy assays for various applications. Notably, compared to conventional liquid biomarkers, EV-miRNAs are more advantageous in representing host-cell molecular architecture and exhibiting higher stability and specificity. Despite various available techniques for EV-miRNA separation, concentration, profiling, and data analysis, a standardized approach for EV-miRNA biomarker development is yet lacking. In this review, we performed a substantial literature review and distilled an integrated workflow encompassing important steps for EV-miRNA biomarker development, including sample collection and EV isolation, EV-miRNA extraction and quantification, high-throughput data preprocessing, biomarker prioritization and model construction, functional analysis, as well as validation. With the rapid growth of "big data", we highlight the importance of efficient mining of high-throughput data for the discovery of EV-miRNA biomarkers and integrating multiple independent datasets for in silico and experimental validations to increase the robustness and reproducibility. Furthermore, as an efficient strategy in systems biology, network inference provides insights into the regulatory mechanisms and can be used to select functionally important EV-miRNAs to refine the biomarker candidates. Despite the encouraging development in the field, a number of challenges still hinder the clinical translation. We finally summarize several common challenges in various biomarker studies and discuss potential opportunities emerging in the related fields.

Dysregulation of miR-638 in the progression of cancers

MicroRNA (miRNA) is a form of short, single-stranded and non-coding RNA that is important in regulating the post-transcriptional modification of multiple downstream targets. Many miRNAs have been reported to involve in controlling the progression of human diseases, and one of them is miR-638, which play essential roles in regulating the development of human cancer. By targeting the 3'-ends of its targets, miR-638 can regulate cellular processes including proliferation, invasion, metastases, angiogenesis, apoptosis and inflammation. This review was aimed to summarize current findings on the roles of miR-638 in different human cancers based on the results from various in vitro, in vivo and clinical studies. The biogenesis process and tissue expression, followed by the roles of miR-638 in regulating the development of various human cancers by targeting different downstream targets were covered in this review. The potential applications and challenges of employing miR-638 as cancer biomarker and therapeutic agent were also discussed.