Circulating microRNA-203 predicts metastases, early recurrence, and poor prognosis in human gastric cancer

Role of exosomal miRNAs and macrophage polarization in gastric cancer: A novel therapeutic strategy

Gastric cancer (GC) is one of the most common gastrointestinal cancers worldwide, with consistently high morbidity and mortality rates and poor prognosis. Most patients are diagnosed at an advanced stage due to the lack of specific presentation in the early stages. Exosomes are a class of extracellular vesicles (EVs) widely found in body fluids and can release genetic material or multiple proteins to facilitate intercellular communication. In recent years, exosomal miRNAs have gained attention for their role in various cancers. These exosomal miRNAs can impact GC development and progression by targeting specific genes or influencing signaling pathways and cytokines involved in Angiogenesis, epithelial-mesenchymal transition (EMT), drug resistance, and immune regulation. They show great potential in terms of diagnosis, prognosis, and treatment of GC. Notably, the gastrointestinal tract has the largest number of macrophages, which play a significant role in GC progression. Tumor-associated macrophages (TAMs) are the most abundant immune cells in the tumor microenvironment (TME) and can influence macrophage programming through various mediators, including macrophage polarization. Macrophage polarization is involved in inflammatory responses and significantly impacts the GC process.

Targeting non-coding RNAs as a promising biomarker in peritoneal metastasis: Background, mechanism, and therapeutic approach

Peritoneal metastasis (PM) pathophysiology is complex and not fully understood. PM, originating from gastrointestinal (GI) cancer, is a condition that significantly worsens patient prognosis due to its complex nature and limited treatment options. The non-coding RNAs (ncRNAs) have been shown to play pivotal roles in cancer biology, influencing tumorigenesis, progression, metastasis, and therapeutic resistance. Increasing evidence has demonstrated the regulatory functions of different classes of ncRNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) in PM. Identifying biomarkers for early detection of PM is a crucial step towards improving patient outcomes, and how ncRNA profiles correlate with survival rates, response to therapy, and recurrence risks have raised much attention in recent years. Additionally, exploring innovative therapeutic approaches utilizing ncRNAs, such as targeted therapy and gene silencing, may offer new horizons in treating this dire condition. Recent advances in systemic treatments and the development of novel loco-regional therapies have opened doors to multimodal treatment approaches. Radical surgeries combined with hyperthermic intraperitoneal chemotherapy (HIPEC) have shown promising results, leading to extended patient survival. Current research is focused on the molecular characterization of PM, which is crucial for early detection and developing future therapeutic strategies. By summarizing the latest findings, this study underscores the transformative potential of ncRNAs in enhancing the diagnosis, prognosis, and treatment of PM in GI cancer, paving the way for more personalized and effective clinical strategies.

miR-1286, a Tumor Suppressor of Gastric Cancer, Serves as a Promising Biomarker for Screening Gastric Cancer from Gastritis

Gastric cancer (GC) is one of the crucial causes of cancer-associated death worldwide. This study aimed to investigate the biological function of miR-1286 in GC progression in vitro, evaluate the clinical value of serum miR-1286 to screen GC patients and explore its relationship with helicobacter pylori (HP) infection and peritoneal metastasis in GC patients. Expression of miR-1286 was measured by RT-qPCR. Cell Counting Kit-8 assay was utilized for measuring GC cell proliferation ability. The migration and invasion abilities of GC cells were measured using Transwell assays. Serum samples were obtained from 108 GC patients, 62 gastritis cases and 62 healthy volunteers. The diagnostic performance of miR-1286 was assessed using ROC analysis, and the predictive value of miR-1286 for peritoneal metastasis onset was analyzed using logistic regression analysis. miR-1286 played as a tumor suppressor in GC progression by inhibiting GC cell proliferation, migration and invasion. In GC patients, significantly decreased miR-1286 was observed compared to gastritis and healthy controls, and had considerable diagnostic accuracy to distinguish GC from the controls. A significant association was found between miR-1286 expression and HP infection, peritoneal metastasis and TNM stage. Moreover, miR-1286 was lowly expressed in GC patients with peritoneal metastasis, and independently predicted the occurrence of peritoneal metastasis in GC. miR-1286 acts as a tumor suppressor and a biomarker in GC, and is closely associated with HP infection and peritoneal metastasis onset. The methods to regulate miR-1286 may be novel strategies to improve the treatment of GC.

The role of microRNAs in the gastric cancer tumor microenvironment

BACKGROUND

Gastric cancer (GC) is one of the deadliest malignant tumors with unknown pathogenesis. Due to its treatment resistance, high recurrence rate, and lack of reliable early detection techniques, a majority of patients have a poor prognosis. Therefore, identifying new tumor biomarkers and therapeutic targets is essential. This review aims to provide fresh insights into enhancing the prognosis of patients with GC by summarizing the processes through which microRNAs (miRNAs) regulate the tumor microenvironment (TME) and highlighting their critical role in the TME.

MAIN TEXT

A comprehensive literature review was conducted by focusing on the interactions among tumor cells, extracellular matrix, blood vessels, cancer-associated fibroblasts, and immune cells within the GC TME. The role of noncoding RNAs, known as miRNAs, in modulating the TME through various signaling pathways, cytokines, growth factors, and exosomes was specifically examined. Tumor formation, metastasis, and therapy in GC are significantly influenced by interactions within the TME. miRNAs regulate tumor progression by modulating these interactions through multiple signaling pathways, cytokines, growth factors, and exosomes. Dysregulation of miRNAs affects critical cellular processes such as cell proliferation, differentiation, angiogenesis, metastasis, and treatment resistance, contributing to the pathogenesis of GC.

CONCLUSIONS

miRNAs play a crucial role in the regulation of the GC TME, influencing tumor progression and patient prognosis. By understanding the mechanisms through which miRNAs control the TME, potential biomarkers and therapeutic targets can be identified to improve the prognosis of patients with GC.

MiR-203 improves cardiac dysfunction by targeting PARP1-NAD+ axis in aging murine

Heart aging is a prevalent cause of cardiovascular diseases among the elderly. NAD+ depletion is a hallmark feature of aging heart, however, the molecular mechanisms that affect NAD+ depletion remain unclear. In this study, we identified microRNA-203 (miR-203) as a senescence-associated microRNA that regulates NAD+ homeostasis. We found that the blood miR-203 level negatively correlated with human age and its expression significantly decreased in the hearts of aged mice and senescent cardiomyocytes. Transgenic mice with overexpressed miR-203 (TgN (miR-203)) showed resistance to aging-induced cardiac diastolic dysfunction, cardiac remodeling, and myocardial senescence. At the cellular level, overexpression of miR-203 significantly prevented D-gal-induced cardiomyocyte senescence and mitochondrial damage, while miR-203 knockdown aggravated these effects. Mechanistically, miR-203 inhibited PARP1 expression by targeting its 3'UTR, which helped to reduce NAD+ depletion and improve mitochondrial function and cell senescence. Overall, our study first identified miR-203 as a genetic tool for anti-heart aging by restoring NAD+ function in cardiomyocytes.

Non-coding RNAs and gastrointestinal cancers prognosis: an umbrella review of systematic reviews and meta-analyses of observational studies

Aim

Provide an overview and a systematic evaluation of the evidence quality on the association between non-coding RNAs (ncRNAs) and prognosis value for gastrointestinal cancers (GICs).

Methods

We searched the literature from three electronic databases: Pubmed, Embase, and Web of science, then carefully screened and extracted the primary information and results from the included articles. We use A measurable systematic review and meta-analysis evaluation tool (AMSTAR2) to evaluate the quality of methodology and then use the Grading of Recommendations Assessment 2, Development and Evaluation guideline (GRADE) make sure the reliability of the meta-analysis.

Results

Overall, 182 meta-analyses from 58 studies were included in this study. Most of these studies are of low or very low quality. Using the scoring tool, we found that only two meta-analyses were rated as high reliability, and 17 meta-analyses were rated as medium reliability.

Conclusions

Although ncRNA has good prognostic value in some studies, only a tiny amount of evidence is highly credible at present. More research is needed in the future.

PROSPERO registration number

CRD42022382296.

A liquid biopsy signature for predicting early recurrence in patients with gastric cancer

BACKGROUND

Gastric cancer (GC) patients who experience recurrence within the first year following surgery (early recurrence [ER]) exhibit worse prognosis. Herein, we established a microRNA-based liquid biopsy assay to predict ER in GC patients.

METHODS

A comprehensive biomarker discovery was performed by analysing miRNA expression profiling in 271 primary GC tumours. Thereafter, the expression of these biomarkers was validated in 290 GC cases, which included 218 tissues and 72 pre-treatment sera, from two independent institutions.

RESULTS

A panel of 8 miRNAs was identified during the initial biomarker discovery, and this panel could robustly predict ER in a tissue-based clinical cohort (area under the curve [AUC]: 0.81). Furthermore, a model combining the miRNA panel, microsatellite instability (MSI) status and tumour size exhibited superior predictive performance (AUC: 0.86), and was defined as a Prediction of Early Recurrence in GC (PERGC) signature, which was successfully validated in another independent cohort (AUC: 0.82). Finally, the PERGC signature was translated into a liquid biopsy assay (AUC: 0.81), and a multivariate regression analysis revealed this signature to be an independent predictor for ER (odds ratio: 11.20).

CONCLUSION

We successfully established a miRNA-based liquid biopsy signature that robustly predicts the risk of ER in GC patients.

MiR-200/183 family-mediated module biomarker for gastric cancer progression: an AI-assisted bioinformatics method with experimental functional survey

BACKGROUND

Gastric cancer (GC) is a major cancer burden throughout the world with a high mortality rate. The performance of current predictive and prognostic factors is still limited. Integrated analysis is required for accurate cancer progression predictive biomarker and prognostic biomarkers that help to guide therapy.

METHODS

An AI-assisted bioinformatics method that combines transcriptomic data and microRNA regulations were used to identify a key miRNA-mediated network module in GC progression. To reveal the module's function, we performed the gene expression analysis in 20 clinical samples by qRT-PCR, prognosis analysis by multi-variable Cox regression model, progression prediction by support vector machine, and in vitro studies to elaborate the roles in GC cells migration and invasion.

RESULTS

A robust microRNA regulated network module was identified to characterize GC progression, which consisted of seven miR-200/183 family members, five mRNAs and two long non-coding RNAs H19 and CLLU1. Their expression patterns and expression correlation patterns were consistent in public dataset and our cohort. Our findings suggest a two-fold biological potential of the module: GC patients with high-risk score exhibited a poor prognosis (p-value < 0.05) and the model achieved AUCs of 0.90 to predict GC progression in our cohort. In vitro cellular analyses shown that the module could influence the invasion and migration of GC cells.

CONCLUSIONS

Our strategy which combines AI-assisted bioinformatics method with experimental and clinical validation suggested that the miR-200/183 family-mediated network module as a "pluripotent module", which could be potential marker for GC progression.

Application progress of liquid biopsy in gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors globally. Guiding the individualized treatment of GC is the focus of research. Obtaining representative biological samples to study the biological characteristics of GC is the focus of diagnosis and treatment of GC. Liquid biopsy technology can use high-throughput sequencing technology to detect biological genetic information in blood. Compared with traditional tissue biopsy, liquid biopsy can determine the dynamic changes of tumor. As a noninvasive auxiliary diagnostic method, liquid biopsy can provide diagnostic and prognostic information concerning the progression of the disease. Liquid biopsy includes circulating tumor cells, circulating tumor DNA, circulating tumor RNA, tumor educated platelets, exosomes, and cytokines. This article describes the classification of liquid biopsy and its application value in the occurrence, development, and therapeutic efficacy of GC.

Comprehensive analysis of competitive endogenous RNAs network: Identification and validation of prediction model composed of mRNA signature and miRNA signature in gastric cancer

Gastric cancer (GC), one of the most lethal malignant tumors, is highly aggressive with a poor prognosis, while the molecular mechanisms underlying it remain largely unknown. Although advanced imaging techniques and comprehensive treatment facilitate the diagnosis and survival of some GC patients, the precise diagnosis and prognosis are still a challenge. The present study used publicly available gene expression profiles from The Cancer Genome Atlas and Gene Expression Omnibus datasets including mRNA, micro (mi)RNA and circular (circ)RNA of GC to establish a competing endogenous RNA network (ceRNA). Further, the present study performed least absolute shrinkage and selector operator regression analysis on the hub RNAs to establish a prediction model with mRNA and miRNA. The ceRNA network contained 109 edges and 56 nodes and the visible network contains 13 miRNAs, 9 circRNAs and 34 mRNAs. The five mRNA-based signature were CTF1, FKBP5, RNF128, GSTM2 and ADAMTS1. The area under curve (AUC) value of the diagnosis training cohort was 0.9975. The prognosis of the high-risk group (RiskScore >4.664) was worse compared with that of the low-risk group (RiskScore ≤4.664; P<0.05) in the training cohort. The five miRNA-based signature were miR-145-5p, miR-615-3p, miR-6507-5p, miR-937-3p and miR-99a-3p. The AUC value of the diagnosis training cohort was 0.9975. The prognosis of the high-risk group (RiskScore >1.621) was worse compared with that of the low-risk group (RiskScore ≤1.621; P<0.05) in the training cohort. The validation cohorts indicated that both five mRNA and five miRNA-based signatures had strong predictive power in diagnosis and prognosis for GC. In conclusion, a ceRNA network was established for GC and a five mRNA-based signature and a five miRNA-based signature was identified that enabled diagnosis and prognosis of GC by assigning patient to a high-risk group or low-risk group.

Non-Coding RNAs in Gastric Cancer: From Malignant Hallmarks to Clinical Applications

Gastric cancer (GC) is one of the most lethal malignancies worldwide. However, the molecular mechanisms underlying gastric carcinogenesis remain largely unknown. Over the past decades, advances in RNA-sequencing techniques have greatly facilitated the identification of various non-coding RNAs (ncRNAs) in cancer cells, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Accumulating evidence has revealed that ncRNAs are essential regulators in GC occurrence and development. However, ncRNAs represent an emerging field of cancer research, and their complex functionality remains to be clarified. Considering the lack of viable biomarkers and therapeutic targets in GC, further studies should focus on elucidating the intricate relationships between ncRNAs and GC, which can be translated into clinical practice. In this review, we summarize recent research progress on how ncRNAs modulate the malignant hallmarks of GC, especially in tumor immune escape, drug resistance, and stemness. We also discuss the promising applications of ncRNAs as diagnostic biomarkers and therapeutic targets in GC, aiming to validate their practical value for clinical treatment.

Genomewide Expression Profiling Identifies a Novel miRNA-based Signature for the Detection of Peritoneal Metastasis in Patients With Gastric Cancer

OBJECTIVE

This study aimed to conduct a genomewide transcriptomic profiling to develop a microRNA (miRNA)-based signature for the identification of peritoneal metastasis (PM) in patients with gastric cancer (GC).

SUMMARY BACKGROUND DATA

Even though PM in patients with GC has long been recognized to associate with poor prognosis, currently there is lack of availability of molecular biomarkers for its robust diagnosis.

METHODS

We performed a systematic biomarker discovery by analyzing miRNA expression profiles in primary tumors from GC patients with and without PM, and subsequently validated the expression of candidate miRNA biomarkers in 3 independent clinical cohorts of 354 patients with advanced GC.

RESULTS

Five miRNAs (miR-30a-5p, -134-5p, -337-3p, -659-3p, and -3917) were identified during the initial discovery phase; three of which (miR-30a-5p, -659-3p, and -3917) were significantly overexpressed in the primary tumors from PM-positive patients in the testing cohort (P = 0.002, 0.04, and 0.007, respectively), and distinguished patients with versus without peritoneal metastasis with the value of area under the curve (AUC) of 0.82. Furthermore, high expression of these miRNAs also associated with poor prognosis (hazard ratio = 2.18, P = 0.04). The efficacy of the combination miRNA signature was subsequently validated in an independent validation cohort (AUC = 0.74). Finally, our miRNA signature when combined together with the macroscopic Borrmann's type score offered a much superior diagnostic in all 3 cohorts (AUC = 0.87, 0.76, and 0.79, respectively).

CONCLUSIONS

We have established an miRNA-based signature that have a potential to identify peritoneal metastasis in GC patients.

Clinical Applications of Liquid Biopsy in Gastric Cancer

Liquid biopsy represents an exciting new area in the field of cancer diagnosis and management, offering a less invasive and more convenient approach to obtain a time-point image of the tumor burden and its genomic profile. Samples collected from several body fluids, mostly blood, can be used to gain access to circulating tumor cells and DNA, non-coding RNAs, microRNAs, and exosomes, at any moment, offering a dynamic picture of the tumor. For patients with GC, the use of blood-based biopsies may be particularly beneficial since tissue biopsies are difficult to obtain and cause real distress to the patient. With advantages such as repeatability and minimal invasion, it is no wonder that the field of liquid biopsy has received tremendous attention. However, the abundance of studies, involving a wide range of assays with different principles, prevented for the moment the reproducibility of the results and therefore the translation into the clinic of liquid biopsy. In this review, we present the latest technical development and data on circulating biomarkers available through liquid biopsy in gastric cancer with an emphasis on their clinical utility in areas such as cancer screening, prognostic stratification, and therapeutic management.

Long non-coding RNAs as the critical regulators of doxorubicin resistance in tumor cells

Resistance against conventional chemotherapeutic agents is one of the main reasons for tumor relapse and poor clinical outcomes in cancer patients. Various mechanisms are associated with drug resistance, including drug efflux, cell cycle, DNA repair and apoptosis. Doxorubicin (DOX) is a widely used first-line anti-cancer drug that functions as a DNA topoisomerase II inhibitor. However, DOX resistance has emerged as a large hurdle in efficient tumor therapy. Furthermore, despite its wide clinical application, DOX is a double-edged sword: it can damage normal tissues and affect the quality of patients’ lives during and after treatment. It is essential to clarify the molecular basis of DOX resistance to support the development of novel therapeutic modalities with fewer and/or lower-impact side effects in cancer patients. Long non-coding RNAs (lncRNAs) have critical roles in the drug resistance of various tumors. In this review, we summarize the state of knowledge on all the lncRNAs associated with DOX resistance. The majority are involved in promoting DOX resistance. This review paves the way to introducing an lncRNA panel marker for the prediction of the DOX response and clinical outcomes for cancer patients.

Circulating MicroRNAs in Gastrointestinal Cancer

Simple Summary

The screening methods and therapeutic strategies for gastrointestinal cancer (GIC) have improved, but mortality in GIC patients remains high. Early detection and precise evaluation of GIC are required to further improve treatment outcomes in GIC patients. MicroRNAs (miRNAs), which do not encode proteins, have attracted attention as biomarkers of various diseases. Since the first report revealing the strong correlation between miRNAs and cancer in 2002, numerous studies have illustrated the changes in the expression and the biological and oncological effects of miRNAs in GIC. Furthermore, miRNAs circulating in the blood are reported to be associated with GIC status. These miRNAs are thought to be useful as noninvasive biomarkers because of their stability in blood. Herein, we discuss the potential of miRNAs as noninvasive biomarkers for each type of GIC on the basis of previous reports and describe perspectives for their future application.

Abstract

Gastrointestinal cancer (GIC) is a common disease and is considered to be the leading cause of cancer-related death worldwide; thus, new diagnostic and therapeutic strategies for GIC are urgently required. Noncoding RNAs (ncRNAs) are functional RNAs that are transcribed from the genome but do not encode proteins. MicroRNAs (miRNAs) are short ncRNAs that are reported to function as both oncogenes and tumor suppressors. Moreover, several miRNA-based drugs are currently proceeding to clinical trials for various diseases, including cancer. In recent years, the stability of circulating miRNAs in blood has been demonstrated. This is of interest because these miRNAs could be potential noninvasive biomarkers of cancer. In this review, we focus on circulating miRNAs associated with GIC and discuss their potential as novel biomarkers.

Recent advances of miRNAs in the development and clinical application of gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors. The mechanism of how GC develops is vague, and therapies are inefficient. The function of microRNAs (miRNAs) in tumorigenesis has attracted the attention from many scientists. During the development of GC, miRNAs function in the regulation of different phenotypes, such as proliferation, apoptosis, invasion and metastasis, drug sensitivity and resistance, and stem-cell-like properties. MiRNAs were evaluated for use in diagnostic and prognostic predictions and exhibited considerable accuracy. Although many problems exist for the application of therapy, current studies showed the antitumor effects of miRNAs. This paper reviews recent advances in miRNA mechanisms in the development of GC and the potential use of miRNAs in the diagnosis and treatment of GC.

MicroRNA-653-5p Promotes Gastric Cancer Proliferation and Metastasis by Targeting the SOCS6-STAT3 Pathway

MicroRNAs (miRNAs) are emerging as significant regulators of the tumorigenesis of gastric cancer (GC), and may be effective biomarkers for diagnosis, prognosis, and therapeutic targeting for GC. In this study, miR-653-5p was found to be significantly upregulated in GC tissues, serum, and cell lines and was strongly associated with poor prognosis in patients with GC. Furthermore, miR-653-5p promoted GC cell proliferation and metastasis in vivo and in vitro. Suppressor of cytokine signaling 6 (SOCS6) was directly targeted by miR-653-5p, and SOCS6 attenuated miR-653-5p-mediated GC cell growth, migration, and invasion. In addition, SOCS6-mediated inactivation of the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway was also reversed by the administration of miR-653-5p. The findings from this study support a novel regulatory axis between miR-653-5p, SOCS6, and JAK2/STAT3 that may be a target for diagnosis and therapeutic intervention for GC.

miR-96-5p enhances cell proliferation and invasion via targeted regulation of ZDHHC5 in gastric cancer

Objective: To explore the biological function and mechanism of miR-96-5p in gastric cancer.

Methods: The expression of differently expressed microRNAs (DEMs) related to gastric adenocarcinoma (GAC) prognosis was identified in GAC tumor samples and adjacent normal samples by qRT-PCR. A target gene miR-96-5p was selected using TargetScan, miRTarBase, miRDB databases. The combination of miR-96-5p and ZDHHC5 was verified by luciferase receptor assay. To further study the function and mechanism of miR-96-5p, we treated MGC-803 cells with miR-96-5p inhibitor and si-ZDHHC5, then detected cell viability, apoptosis, migration and invasion ability, as well as the expression of ZDHHC5, Bcl-2, Bax, cleaved caspase-3, cleaved caspase-9, and COX-2 by Western blot.

Results: Compared with adjacent normal samples, the levels of miR-96-5p, miR-222-5p, and miR-652-5p were remarkably increased, while miR-125-5p, miR-145-3p, and miR-379-3p were significantly reduced in GAC tumor samples (P<0.01), which were consistent with bioinformatics analysis. Furthermore, ZDHHC5 was defined as a direct target gene of miR-96-5p. miR-96-5p silence significantly reduced cell viability, increased cell apoptosis, and suppressed cell migration and invasion, as well as inhibited the expression of Bcl-2 and COX-2 and promoted Bax, cleaved caspase-3 and cleaved caspase-9 level in MGC-803 cells (P<0.01). Notably, ZDHHC5 silence reversed the inhibiting effects of miR-96-5p on MGC-803 cells growth and metastasis

Conclusion: Our findings identified six microRNAs (miRNAs; miR-96-5p, miR-222-5p, miR-652-5p, miR-125-5p, miR-145-3p, and miR-379-3p) related to GAC prognosis, and suggested that down-regulated miR-96-5p might inhibit tumor cell growth and metastasis via increasing ZDHHC5 expression enhance MGC-803 cell apoptosis, as well as decrease MGC-803 cell metastasis.

Circulating microRNAs: Biomarkers of disease

MicroRNAs are a class of endogenous noncoding single-stranded RNA molecules with approximately 20-24 nucleotides and are associated with a broad range of biological processes. Researchers found that microRNAs are abundant in tissues, and more importantly, there are also trace circulating microRNAs that exist in biological fluids. In recent years, circulating microRNAs had emerged as promising diagnostic and prognostic biomarkers for the noninvasive detection of diseases with high specificity and sensitivity. More importantly, specific microRNA expression signatures reflect not only the existence of early-stage diseases but also the dynamic development of advanced-stage diseases, disease prognosis prediction, and drug resistance. To date, an increasing number of potential miRNA biomarkers have been reported, but their practical application prospects are still unclear. Therefore, microRNAs, as potential diagnostic and prognostic biomarkers in a variety of diseases, need to be updated, as they are of great importance in the diagnosis, prognosis and prediction of therapeutic responses. In this review, we summary our current understanding of microRNAs as potential biomarkers in the major diseases (e.g., cancers and cardio-cerebrovascular diseases), which provide the basis for the design of diagnosis and treatment plan and the improvement of the cure rate.

Non-coding RNAs in gastric cancer

Non-coding RNAs (ncRNAs) are functional RNA molecules that play crucial regulatory roles in many fundamental biological processes. The dysregulation of ncRNAs is significantly associated with the progression of human cancers, including gastric cancer. In this review, we have summarized the oncogenic or tumor-suppressive roles and the regulatory mechanisms of lncRNAs, miRNAs, circRNAs and piRNAs, and have discussed their potential as biomarkers or therapeutic targets in gastric cancer.

The circulating miRNAs as diagnostic and prognostic markers

A large portion of the human genome transcribes RNA sequences that do not code for any proteins. The first of these sequences was identified in 1993, and the best known noncoding RNAs are microRNA (miRNAs). It is now fully established that miRNAs regulate approximately 30% of the known genes that codify proteins. miRNAs are involved in several biological processes, like cell proliferation, differentiation, apoptosis and metastatization. These RNA products regulate gene expression at the post-transcriptional level, modulating or inhibiting protein expression by interacting with specific sequences of mRNAs. Mature miRNAs can be detected in blood plasma, serum and also in a wide variety of biological fluids. They can be found associated with proteins, lipids as well as enclosed in exosome vesicles. We know that circulating miRNAs (C-miRNAs) can regulate several key cellular processes in tissues different from the production site. C-miRNAs behave as endogenous mediators of RNA translation, and an extraordinary knowledge on their function has been obtained in the last years. They can be secreted in different tissue cells and associated with specific pathological conditions. Significant evidence indicates that the initiation and progression of several pathologies are "highlighted" by the presence of specific C-miRNAs, underlining their potential diagnostic relevance as clinical biomarkers. Here we review the current literature on the possible use of this new class of molecules as clinical biomarkers of diseases.

Circulating microRNAs as biomarkers in cancer diagnosis

MicroRNAs (miRNAs) are a group of tiny molecules of 18-22 nucleotide long noncoding RNA that regulate the post-transcriptional gene expression through translational inhibition and/or mRNA destabilization. Because of their involvement in important developmental processes, it is highly likely that the altered expression of miRNAs could be associated with abnormal conditions like suboptimal growth or diseases. Thus, the expression of miRNAs can be used as biomarkers in pathophysiological conditions. Recently, a handful of miRNAs are detected in cell-free conditions including biofluids and cell culture media and they exhibit specific expression patterns that are associated with altered physiological conditions. Extracellular miRNAs are not only extremely stable outside cells in a variety of biofluids but also they are easy to acquire. These characteristics led to the idea of using extracellular miRNAs as a potential biomarker for the onset and prognosis of cancer. Although miRNAs have been proposed as a potential diagnostic tool for cancer detection, their application in the routine clinical investigation is yet to come. First, this review will provide an insight into the extracellular miRNAs, particularly, their release mechanisms and characteristics, and the potential of extracellular miRNAs as a biomarker in cancer detection. Finally, it will discuss the potential of using extracellular miRNAs in different cancer diagnoses and challenges associated with the clinical application of extracellular miRNAs as noninvasive biomarkers.

Serum miR-191 and miR-425 as Diagnostic and Prognostic Markers of Advanced Gastric Cancer Can Predict the Sensitivity of FOLFOX Chemotherapy Regimen

Purpose

miR-191 and miR-425 have been proved to be highly expressed in gastric carcinoma (GC). However, little research has been done on their clinical value in serum of patients with advanced GC. In addition, it is not clear whether they can be used as markers for the response and prognosis of GC patients treated with oxaliplatin combined with 5-fluorouracil and FOLFOX chemotherapy.

Patients and Methods

A total of 230 patients with advanced GC admitted to our hospital were selected as the study objects, all of whom received FOLFOX chemotherapy regimen. Another 100 cases of healthy subjects were included. QRT-PCR was employed to detect the serum expression of miR-191 and miR-425 in patients.

Results

Compared with the healthy subjects, the serum expressions of miR-191 and miR-425 in GC patients were significantly upregulated, which were correlated with differentiation degree and TNM staging, respectively. According to the ROC curve, the AUC of miR-191 and miR-425 for GC diagnosis was 0.937 and 0.901, respectively, while the AUC for differentiation degree diagnosis was 0.854 and 0.822, and that for TNM staging diagnosis was 0.860 and 0.829, respectively. The predictive AUC of miR-191 and miR-425 for chemosensitivity was 0.868 and 0.835, respectively, with a combined predictive AUC of 0.935. Low differentiation degree, high TNM staging, high miR-191 and high miR-425 expressions were independent risk factors for chemotherapy insensitivity. Differentiation degree, TNM staging, chemotherapy effect, miR-191 and miR-425 were independent influencing factors for the prognosis of GC patients.

Conclusion

Up-regulated expression of miR-191 and miR-425 in the serum of patients with advanced GC are effective biomarkers for the diagnosis, chemotherapy and prognosis evaluation of GC.

Serum miR-551b-3p is a potential diagnostic biomarker for gastric cancer

BACKGROUND/AIMS

Gastric cancer (GC) is one of the most common gastrointestinal malignancies. Many studies have demonstrated that serum microRNAs have potential applications as non-invasive biomarkers for cancer diagnosis. The aim of the present study was to investigate the expression of serum miR-551b-3p in patients with GC and to explore its potential as a diagnostic biomarker in GC.

MATERIALS AND METHODS

The expression of miR-551b-3p was detected using quantitative reverse transcription polymerase chain reaction in preoperative serum samples of 50 patients with GC and 53 healthy individuals. An analysis was performed to determine the correlation between serum miR-551b-3p levels and clinicopathological characteristics of patients with GC. The receiver operating characteristic curve was generated, and the cut-off point of serum miR-551b-3p for the diagnosis of GC was selected. The clinical value of serum miR-551b-3p for GC was analyzed by a consistency test.

RESULTS

The expression of serum miR-551b-3p was significantly lower in patients with GC than in healthy individuals (p=0.000). Low level was positively associated with tumor size (p=0.014), depth of invasion (p=0.001), and Tumor-Node-Metastasis stage (p=0.022). The area under the curve for serum miR-551b-3p distinguishing patients with GC from healthy individuals was 0.860 (95% CI: 0.787-0.933, p=0.000), with a specificity of 96.2% and a sensitivity of 70%. The kappa consistency test had a kappa value of 0.667 (p=0.000) in GC.

CONCLUSION

Serum miR-551b-3p may potentially serve as a diagnostic biomarker for GC.

MiR-96-5p inhibition induces cell apoptosis in gastric adenocarcinoma

BACKGROUND

Gastric adenocarcinoma (GAC) mortality rates have remained relatively changed over the past 30 years, and it continues to be one of the leading causes of cancer-related death.

AIM

To search for novel miRNAs related to GAC prognosis and further investigate the effect of miR-96-5p on MGC-803 cells.

METHODS

The miRNA expression profile data of GAC based on The Cancer Genome Atlas were obtained and used to screen differently expressed miRNAs (DEMs) and DEMs related to GAC prognosis. Then, the expression of DEMs related to GAC prognosis was identified in GAC tumor samples and adjacent normal samples by qRT-PCR. The target gene, ZDHHC5, of miR-96-5p was predicted using TargetScan, miRTarBase, and miRDB databases and confirmed by luciferase reporter assay. Furthermore, MGC-803 cells were transfected with inhibitor NC, miR-96-5p inhibitor, si-ZDHHC5, or miR-96-5p inhibitor + si-ZDHHC5, and then cell apoptosis was detected by flow cytometry. The expression of ZDHHC5, Bcl-2, and COX-2 was detected using western blotting.

RESULTS

A total of 299 DEMs and 35 DEMs related to GAC prognosis were screened based on The Cancer Genome Atlas. Then compared with adjacent normal samples, the levels of miR-96-5p, miR-222-5p, and miR-652-5p were remarkably increased, while miR-125-5p, miR-145-3p, and miR-379-3p levels were reduced in GAC tumor samples (P < 0.01), which were consistent with bioinformatics analysis. Furthermore, ZDHHC5 was defined as a direct target gene of miR-96-5p. miR-96-5p inhibition increased the number of apoptotic cells as well as promoted the expression of ZDHHC5, Bcl-2, and COX-2 in MGC-803 cells (P < 0.01). After ZDHHC5 inhibition, the number of apoptotic cells and the expression of ZDHHC5, Bcl-2, and COX-2 were reduced. The addition of an miR-96-5p inhibitor partly reversed these effects (P < 0.01).

CONCLUSION

Our findings identified six miRNAs related to GAC prognosis and suggested that downregulated miR-96-5p might induce cell apoptosis via upregulating ZDHHC5 expression in MGC-803 cells.

Association Between Liquid Biopsy and Prognosis of Gastric Cancer Patients: A Systematic Review and Meta-Analysis

Background: Reports regarding liquid biopsy and gastric cancer (GC) have emerged rapidly in recent decades, yet their prognostic value still remains controversial. This study was aimed to assess the impact of liquid biopsy, including circulating tumor cells (CTCs) and cell-free nucleic acids, on GC patients' prognosis.

Methods: PubMed, Medline, EMBASE, and ClinicalTrial.gov databases were searched for studies that report GC patient survival data stratified by CTC/circulating tumor DNA (ctDNA)/circulating miRNAs' status. The hazard ratios (HRs) and their 95% confidence intervals (CIs) for patients' overall survival (OS) and disease-free survival (DFS)/progression-free survival (PFS) were recorded or calculated depending on circulating target status.

Results: We initially identified 4,221 studies, from which 43 were eligible for further analysis, comprising 3,814 GC patients. Pooled analyses showed that detection of certain CTCs, ctDNA, and circulating miRNA was associated with poorer OS (CTCs: HR = 1.84, 95%CI 1.50–2.26, p < 0.001; ctDNA: HR = 1.78, 95%CI 1.36–2.34, p < 0.001; circulating miRNA: HR = 1.74, 95%CI 1.13–2.69, p < 0.001) and DFS/PFS (CTCs: HR = 3.39, 95%CI 2.21–5.20, p < 0.001; ctDNA: HR = 2.38, 95%CI 1.31–4.32, p = 0.004; circulating miRNA: HR = 3.30, 95%CI 2.39–4.55, p < 0.001) of GC patients, regardless of disease stage and time point at which sample is taken (at baseline or post-treatment).

Conclusions: The presence of CTCs and/or cellular components identifies a group of GC with poorer prognosis. Among circulating markers, CTCs demonstrated a stronger and more stable predictive value for late-stage disease and among Mongolian populations with GC. Less data are available for ctDNA and miRNA; however, their presence may also reflect aggressive biology and warrants further prospective study.

MicroRNA-A Tumor Trojan Horse for Tumor-Associated Macrophages

MicroRNAs (miRs) significantly contribute to the regulation of gene expression, by virtue of their ability to interact with a broad, yet specific set of target genes. MiRs are produced and released by almost every cell type and play an important role in horizontal gene regulation in the tumor microenvironment (TME). In the TME, both tumor and stroma cells cross-communicate via diverse factors including miRs, which are taking central stage as a therapeutic target of anti-tumor therapy. One of the immune escape strategies adopted by tumor cells is to release miRs as a Trojan horse to hijack circulating or tumor-localized monocytes/macrophages to tune them for pro-tumoral functions. On the other hand, macrophage-derived miRs exert anti-tumor functions. The transfer of miRs from host to recipient cells depends on the supramolecular structure and composition of miR carriers, which determine the distinct uptake mechanism by recipient cells. In this review, we provide a recent update on the miR-mediated crosstalk between tumor cells and macrophages and their mode of uptake in the TME.

Downregulation of thymopoietin by miR-139-5p suppresses cell proliferation and induces cell cycle arrest/apoptosis in pancreatic ductal adenocarcinoma

MicroRNAs (miRNAs) serve a pivotal role in tumor development and progression, in which miRNA (miR)-139-5p functions as a tumor suppressor. However, the functions and mechanisms of miR-139-5p in pancreatic ductal adenocarcinoma (PDAC) remain unclear. In the present study, it was found that miR-139-5p was markedly decreased in PDAC tissues and cell lines. Noticeably, thymopoietin (TMPO) was predicted and confirmed as a direct target of miR-139-5p using a luciferase reporter system. The expression level of miR-139-5p was inversely associated with the expression of TMPO in PDAC specimens. A series of gain-of-function assays elucidated that the overexpression of miR-139-5p suppressed cell proliferation, and induced cell cycle arrest and cell apoptosis, determined with a Cell Counting Kit-8, colony formation assays and flow cytometry, respectively. Furthermore, the re-expression of TMPO eliminated the effects of miR-139-5p on cell proliferation, cell cycle progression and apoptosis. In summary, these findings demonstrated that miR-139-5p may be a tumor suppressor in PDAC, which may be useful in developing promising therapies for PDAC.

Identification of hsa_circ_0001821 as a Novel Diagnostic Biomarker in Gastric Cancer via Comprehensive Circular RNA Profiling

Background: The morbidity and mortality of gastric cancer (GC) remain high worldwide. With the advent of the Human Genome Sequencing Project, circular RNAs (circRNAs) have attracted widespread attention in cancer research due to their stable ring structure. Our aim was to identify differentially expressed circRNAs in GC and explore their potential roles in GC diagnosis, treatment, and prognostic prediction.

Methods: Large-scale gene screening was performed in three pairs of GC tissues and adjacent noncancerous tissues using high-throughput sequencing. The expression of hsa_circ_0001821 was detected in 80 pairs of tissue samples by quantitative real-time PCR (qRT-PCR). Stability of the ring structure of hsa_circ_0001821 RNA was verified by exonuclease digestion assay, and its diagnostic value was evaluated by receiver operating characteristic (ROC) analysis. In addition, the location of hsa_circ_0001821 in GC cells was detected by nucleoplasm separation assay.

Results: A total of 25,303 circRNAs were identified, among which 2,007 circRNAs were differentially expressed (fold change > 2.0, P < 0.05). Further validation disclosed that hsa_circ_0001821 was significantly downregulated in the 80 pairs of GC tissues and 30 whole-blood specimens obtained from the GC patients. The specificity of hsa_circ_0001821 in GC was higher than that in other solid tumors. In addition, hsa_circ_0001821 was relatively stable after RNA exonuclease digestion. Clinicopathological parameter analysis showed that hsa_circ_0001821 was negatively correlated with tumor depth (r = −0.255, P = 0.022) and lymph node metastasis (r = −0.235, P = 0.036). Area under the curve (AUC) analysis showed that the diagnostic efficiency of circulating hsa_circ_0001821 in distinguishing GC patients was higher than that in GC tissues (0.872, 95%CI: 0.767–0.977 vs. 0.792, 95%CI: 0.723–0.861). Combined use of circulating hsa_circ_0001821 with the existing tumor markers yielded the largest AUC of 0.933. Finally, hsa_circ_0001821 was demonstrated to mainly locate in the cytoplasm, implying that it played a potential regulatory role in GC at the posttranscriptional level.

Conclusion: Hsa_circ_0001821 may prove to be a new and promising potential biomarker for GC diagnosis.

Comprehensive evaluation of FKBP10 expression and its prognostic potential in gastric cancer

FK506 binding protein 10 (FKBP10) has been reported to be dysregulated in numerous types of cancer; however, few reports have investigated FKBP10 in gastric cancer (GC). The aim of the present study was to investigate FKBP10 expression in GC and to analyze its association with the prognosis of patients with GC. FKBP10 mRNA expression was evaluated using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. The standardized mean differences of the meta‑analysis were comprehensively evaluated for FKBP10 expression from a series of GEO datasets. Kaplan‑Meier survival and Cox regression analyses were applied to predict the prognostic value of FKBP10 in patients with GC. Additionally, the protein expression levels of FKBP10 were validated by immunohistochemistry (IHC) in 40 GC and adjacent tissues. FKBP10 co‑expression network and bioinformatics analyses were then used to explore the potential functional mechanisms of FKBP10. The results revealed that the mRNA expression levels of FKBP10 were significantly increased in GC within the TCGA and GEO databases. Survival analysis revealed that high FKBP10 expression results in poorer overall survival and disease‑free survival (P<0.05). Multivariate cox regression analysis indicate FKBP10 as a dependent prognostic factor. The results of IHC indicated that the protein expression levels of FKBP10 were higher in GC tissues than in adjacent non‑GC tissues (P<0.001). Co‑expression networks and functional enrichment analysis suggested that FKBP10 may be involved in the development of GC via cell adhesion molecules and extracellular matrix‑receptor interaction pathways. Therefore, the findings of the present study indicated that FKBP10 is upregulated in GC tissues, and suggests its potential prognostic value. Therefore FKBP10 may be a potential therapeutic target for the treatment of GC.

MiR-203a-3p regulates the biological behaviors of ovarian cancer cells through mediating the Akt/GSK-3β/Snail signaling pathway by targeting ATM

OBJECTIVE

To investigate whether miR-203a-3p can regulate the biological behaviors of ovarian cancer cells by targeting ATM to affect the Akt/GSK-3β/Snail signaling pathway.

METHODS

The expression levels of miR-203a-3p and ATM were detected by qRT-PCR, immunohistochemical staining and Western blotting in ovarian cancer tissues and adjacent normal tissues obtained from 152 subjects. A dual-luciferase reporter gene assay was performed to verify the relationship between miR-203a-3p and ATM. Human ovarian cancer cell lines (A2780 and SKOV3) were used to generate the Blank, miR-NC, miR-203a-3p mimic, Control siRNA, ATM siRNA, and miR-203a-3p inhibitor + ATM siRNA groups. The biological behaviors of ovarian cancer cells were evaluated by CCK-8, wound healing, and Transwell invasion assays, annexin V-FITC/PI staining and flow cytometry. The levels of Akt/GSK-3β/Snail pathway-related proteins were assessed by Western blotting.

RESULTS

Ovarian cancer tissues showed lower miR-203a-3p levels and higher ATM levels than adjacent normal tissues, both of which were associated with the FIGO stage, grade and prognosis of ovarian cancer. As confirmed by a dual-luciferase reporter gene assay, miR-203a-3p could target ATM. Furthermore, the miR-203a-3p mimic had multiple effects, including the inhibition of the proliferation, invasion and migration of A2780 and SKOV3 cells, the promotion of cell apoptosis, the arrest of the cell cycle at the G1 phase, and the blockage of the Akt/GSK-3β/Snail signaling pathway. ATM siRNA had similar effects on the biological behaviors of ovarian cancer cells, and these effects could be reversed by a miR-203a-3p inhibitor.

CONCLUSION

miR-203a-3p was capable of hindering proliferation, migration, and invasion and facilitating the apoptosis of ovarian cancer cells through its modulation of the Akt/GSK-3β/Snail signaling pathway by targeting ATM, and therefore it could serve as a potential therapeutic option for ovarian cancer.

Long non-coding RNA LOXL1-AS1 acts as a ceRNA for miR-324-3p to contribute to cholangiocarcinoma progression via modulation of ATP-binding cassette transporter A1

Accumulating evidence has appreciated long non-coding RNAs (lncRNAs) as novel prognostic markers and therapeutic targets in malignant carcinomas. Here, we aim to investigate the value of a novel cancer-related lncRNA, LOXL1-AS1, in cholangiocarcinoma (CCA). LOXL1-AS1 was found overexpressed in CCA tissues screened by high-throughput sequencing technology. Upregulation of LOXL1-AS1 was identified by TCGA database and qRT-PCR analysis. Additionally, upregulation of LOXL1-AS1 was associated with lymph node invasion, advanced TNM stages and unfavorable prognosis. Loss-of-function and gain-of-function experiments were conducted and validated that LOXL1-AS1 could facilitate cell proliferation, migration and invasion and attenuate cell apoptosis. Moreover, luciferase reporter and rescue assays indicated that LOXL1-AS1 functioned as a ceRNA to elevate ATP-binding cassette transporter A1 (ABCA1) level by sponging miR-324-3p and exhibited the malignant phenotypes of CCA cells, thereby playing an oncogenic role in CCA. Taken together, this study reveals that LOXL1-AS1 might act as a potential biomarker and therapeutic target for CCA clinical application.

Development of a preoperative prediction nomogram for lymph node metastasis in colorectal cancer based on a novel serum miRNA signature and CT scans

BACKGROUND

Preoperative prediction of lymph node (LN) status is of crucial importance for appropriate treatment planning in patients with colorectal cancer (CRC). In this study, we sought to develop and validate a non-invasive nomogram model to preoperatively predict LN metastasis in CRC.

METHODS

Development of the nomogram entailed three subsequent stages with specific patient sets. In the discovery set (n = 20), LN-status-related miRNAs were screened from high-throughput sequencing data of human CRC serum samples. In the training set (n = 218), a miRNA panel-clinicopathologic nomogram was developed by logistic regression analysis for preoperative prediction of LN metastasis. In the validation set (n = 198), we validated the above nomogram with respect to its discrimination, calibration and clinical application.

FINDINGS

Four differently expressed miRNAs (miR-122-5p, miR-146b-5p, miR-186-5p and miR-193a-5p) were identified in the serum samples from CRC patients with and without LN metastasis, which also had regulatory effects on CRC cell migration. The combined miRNA panel could provide higher LN prediction capability compared with computed tomography (CT) scans (P < .0001 in both the training and validation sets). Furthermore, a nomogram integrating the miRNA-based panel and CT-reported LN status was constructed in the training set, which performed well in both the training and validation sets (AUC: 0.913 and 0.883, respectively). Decision curve analysis demonstrated the clinical usefulness of the nomogram.

INTERPRETATION

Our nomogram is a reliable prediction model that can be conveniently and efficiently used to improve the accuracy of preoperative prediction of LN metastasis in patients with CRC.

IL-21R functions as an oncogenic factor and is regulated by the lncRNA MALAT1/miR-125a-3p axis in gastric cancer

Interleukin-21 receptor (IL-21R) is involved in the immunological regulation of immune cells and tumor progression in multiple malignancies. However, the potential molecular mechanisms through which non-coding RNAs (ncRNAs) modulate IL-21R signaling in gastric cancer (GC) remain elusive. In this study, the expression of IL-21R was detected by RT-qPCR and western blot analysis in GC cell lines. The association between IL-21R expression and clinicopathological characteristics and the prognosis of patients with GC was analyzed by immunohistochemistry and Kaplan-Meier plotter analysis. The biological functions of IL-21R were analyzed by a series of in vitro and in vivo experiments, and its regulation by ncRNAs was predicted by bioinformatics analysis and confirmed by luciferase assays and rescue experiments. As a result, the expression of IL-21R was found to be significantly increased in GC cell lines and tissues as compared with normal tissues, and was associated with tumor size and lymphatic metastasis, acting as an independent prognostic factor of poor survival and recurrence in patients with GC. The knockdown of IL-21R markedly suppressed GC cell proliferation and invasion, and IL-21R expression was further validated to be negatively regulated by miR-125a-3p (miR-125a). The overexpression of IL-21R reversed the tumor suppressive effects of miR-125a in vitro and in vivo. Moreover, lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) acted as a sponge of miR-125a to modulate the IL-21R signaling pathway in GC cells and represented a risk factor for survival and recurrence in patients with GC. Taken together, the findings of this study reveal an oncogenic role for IL-21R in gastric tumorigenesis and verify that its activation is partly due to the dysregulation of the lncRNA MALAT1/miR-125a axis. These findings may provide a potential prognostic marker for patients with GC.

MicroRNAs as non-invasive diagnostic biomarkers for gastric cancer: Current insights and future perspectives

Non-invasive diagnostic biomarkers may contribute to an early identification of gastric cancer (GC) and improve the clinical management. Unfortunately, no sensitive and specific screening biomarkers are available yet and the currently available approaches are limited by the nature of the disease. GC is a heterogenic disease with various distinct genetic and epigenetic events that occur during the multifactorial cascade of carcinogenesis. MicroRNAs (miRNAs) are commonly deregulated in gastric mucosa during the Helicobacter pylori infection and in stepwise manner from chronic gastritis, through preneoplastic conditions such as atrophic gastritis and intestinal metaplasia, to early dysplasia and invasive cancer. Identification of miRNAs in blood in 2008 led to a great interest on miRNA-based diagnostic, prognostic biomarkers in GC. In this review, we provide the most recent systematic review on the existing studies related to miRNAs as diagnostic biomarkers for GC. Here, we systematically evaluate 75 studies related to differential expression of circulating miRNAs in GC patients and provide novel view on various heterogenic aspects of the existing data and summarize the methodological differences. Finally, we highlight several important aspects crucial to improve the future translational and clinical research in the field.

MicroRNAs as potential biomarkers for diagnosis, therapy and prognosis of gastric cancer

Despite the widespread use of endoscopy and conventional tumor biomarkers, gastric cancer (GC) remains one of the most frequent causes of cancer-related deaths worldwide due to its late diagnosis and poor response to treatment. Valuable and practical biomarkers are urgently needed to screen patients with a high risk of GC that can complement endoscopic diagnosis. Such biomarkers will enable the efficient prediction of therapeutic response and prognosis of GC patients and favor the establishment of an effective treatment strategy for each and every patient. MicroRNAs (miRNAs) are a class of small non-coding RNA sequences that play important roles in modulating key biological processes by regulating the expression of target genes. Expectedly, miRNAs are abnormally expressed within the tumor tissue and in associated biological fluids of GC patients including their blood, gastric juice, and urine. Accumulating evidence indicates that miRNAs are potential biomarkers with multiple diagnostic functions for GC. Here, we review recent advances and challenges in using miRNAs, particularly biofluid miRNAs, as GC biomarkers with potential clinical applications including diagnosing, clinically staging, and predicting malignant behaviors, therapy response, recurrence after surgery and survival time.

Review of recent efforts to discover biomarkers for early detection, monitoring, prognosis, and prediction of treatment responses of patients with gastric cancer

Gastric cancer (GC) is the leading cause of cancer-related death worldwide. Despite recent advances in diagnosis and therapy, the prognosis of patients with GC is poor. Many patients have inoperable disease upon diagnosis or experience recurrent disease after curative gastrectomy. Unfortunately, tumor markers for GC, such as serum carcinoembryonic antigen and carbohydrate antigen 19-9, lack sufficient sensitivity and specificity. Therefore, effective biomarkers are required to detect early GC and to predict tumor recurrence and chemosensitivity. Areas covered: Here we aimed to review recent developments in techniques that improve the detection of aberrant expression of GC-associated molecules, including protein coding genes, microRNAs, long noncoding RNAs, and methylated promoter DNAs. Expert commentary: Detection of genetic and epigenetic alterations in gastric tissue or in the circulation will likely improve the diagnosis and management of GC to achieve significantly improved outcomes.

HOTAIR enhanced paclitaxel and doxorubicin resistance in gastric cancer cells partly through inhibiting miR-217 expression

Drug resistance is a big obstacle for clinical anti-tumor treatment outcome. However, the role of HOTAIR in drug resistance in gastric cancer (GC) remains unknown. In this study, we showed that overexpression of HOTAIR enhanced paclitaxel and doxorubicin resistance in GC cells. Furthermore, the expression of HOTAIR was upregulated in GC tissues and higher expression of HOTAIR was associated with late stage. In addition, we showed that miR-217 expression was lower in GC tissues compared with the paired non-tumour tissues and downregulated expression of miR-217 was correlated with late stage. Interestingly, the expression of miR-217 was negatively correlated with HOTAIR expression in GC tissues. Ectopic expression of HOTAIR increased GC cell proliferation, cell cycle, and migration. Elevated expression of HOTAIR suppressed miR-217 expression and enhanced GPC5 and PTPN14 expression. Furthermore, we demonstrated that overexpression of miR-217 suppressed paclitaxel and doxorubicin resistance in GC cells. Ectopic expression of HOTAIR promoted drug resistance and increased GC cell proliferation, cell cycle, and migration by targeting miR-217. These data suggested that overexpression of HOTAIR enhanced paclitaxel and doxorubicin resistance in GC cells through inhibiting miR-217 expression.

Liquid biopsy provides new insights into gastric cancer

Liquid biopsies have great promise for precision medicine as they provide information about primary and metastatic tumors via a minimally invasive method. In gastric cancer patients, a large number of blood-based biomarkers have been reported for their potential role in clinical practice for screening, early diagnosis, prognostic evaluation, recurrence monitoring and therapeutic efficiency follow-up. This current review focuses on blood liquid biopsies' role and their clinical implications in gastric cancer patients, with an emphasis on circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) and circulating non-coding RNAs (ncRNAs). We also provide a brief discussion of the potential and limitations of liquid biopsies use and their future use in the routine clinical care of gastric cancer.

microRNA-203 suppresses invasion of gastric cancer cells by targeting ERK1/2/Slug/ E-cadherin signaling

BACKGROUND AND AIMS

Growing evidence suggests that microRNA plays an essential role in the development and metastasis of many tumors, including gastric cancer (GC). Expression of microRNA-203 (miR-203) has been reported to decrease in GC. In addition, overexpression of miR-203 inhibits grow of GC cells in vitro and in vivo. However, whether miR-203 affects cell migration and invasion of GC remains unclear. This study aimed to reveal the role of miR-203 on migration and invasion of GC, and its potential mechanisms.

METHODS

Synthetic pre-miR-203 (miR-203), anti-miR-203 and scrambled negative control RNAs was transfected into the gastric cancer SGC7901 cells to generate miR-203 or anti-miR-203-transfected stable clones. The roles of miR-203 on cell invasion and motility were then analyzed by Transwell migration assay and Wound healing assay in vitro. Using siRNA to targeting ERK1/2, Slug, and E-cadherin or Slug cDNA transfection (to increase Slug expression) to examine the miR-203 signaling pathway. We also examined the efficacies of miR-203 or anti-miR-203 on peritoneal metastasis of SGC7901 cells in the nude mouse model.

RESULTS

Overexpression of miR-203 inhibits SGC7901 cell invasion and motility, followed by decreased phospho-ERK1/2 (pERK1/2) and Slug expression, as well as increased E-cadherin expression. Re-expression of Slug in miR-203/SGC7901cells decreased E-cadherin expression and restored the invasive phenotypes. Targeting E-cadherin in miR-203/SGC7901cells also restored the invasive phenotypes. Inhibition of miR-203 promotes SGC7901 cell invasion and motility, followed by increased phospho-ERK1/2 (pERK1/2) and Slug expression, as well as decreased E-cadherin expression. Targeting ERK1/2 or Slug in anti-miR-203/SGC7901cells increased E-cadherin expression and reversed the invasive phenotypes. In addition, targeting ERK1/2 decreased Slug and increased the E-cadherin expression. Significantly, we found that miR-203 could exert marked inhibition of the peritoneal metastasis of SGC7901 in nude mice in vivo. Targeting miR-203 could exert marked promotion of the peritoneal metastasis of SGC7901 in nude mice in vivo.

CONCLUSIONS

miR-203/ERK1/2/Slug/E-cadherin signaling pathway plays an essential role on SGC7901 cell invasion and motility. miR-203 can be novel modalities to prevent peritoneal metastasis of invasive cancers such as gastric cancer.

Aberrant Expression of Some Circulating miRNAs in Childhood Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a heterogeneous cancer commonly affecting children due to dysregulation of miRNA expression. In the current study, authors investigated the expression profile for miRNA-125b-1 and miRNA-203 among childhood ALL. Blood samples were collected from newly diagnosed childhood ALL and healthy control children. The expression profile for candidate miRNAs was detected using quantitative RT-PCR analysis. Statistical analysis were performed using receiver operating characteristic curve (ROC) to examine the diagnostic efficacy of the two miRNA and their levels among ALL clinicopathological factors and phenotypes. The median expression level for miRNA-125b-1 was significantly high in childhood ALL; while miRNA-203 level was significantly low in childhood ALL as compared to control ones. MiRNA-125-1 reported significant increase in T-ALL as compared to other ALL phenotypes. Median miRNA-203 level was high in T-ALL followed by pre-B-ALL although no significant difference was reported. Clinicopathological factors did not emphasize significance with either detected miRNAs. Using ROC curve the diagnostic efficacy was significant with an area under the curve 0.858 for miRNA-125b-1 (83.72, 100%) and 0.878 for miRNA-203 (97.67, 86.96%). The combination of the two key miRNAs revealed absolute sensitivity (100%). MiRNA-125b-1 and miRNA-203 can be useful molecular markers for diagnosis of ALL. Further studies with large cohort are warranted to validate these results.

MiRNAs at the Crossroads between Innate Immunity and Cancer: Focus on Macrophages

Innate immune cells form an integrative component of the tumor microenvironment (TME), which can control or prevent tumor initiation and progression, due to the simultaneous processing of both anti- and pro-growth signals. This decision-making process is a consequence of gene expression changes, which are in part dependent on post-transcriptional regulatory mechanisms. In this context, microRNAs have been shown to regulate both recruitment and activation of specific tumor-associated immune cells in the TME. This review aims to describe the most important microRNAs that target cancer-related innate immune pathways. The role of exosomal microRNAs in tumor progression and microRNA-based therapeutic strategies are also discussed.

MicroRNA-144 functions as a tumor suppressor in gastric cancer by targeting cyclooxygenase-2

Gastric cancer (GC) poses a serious public health threat and the 5-year survival rate of patients with GC is low. MicroRNAs (miRNAs/miRs) may serve oncogenic or tumor suppressor functions during tumorigenesis by regulating cell proliferation, apoptosis, migration and invasion and it has been demonstrated that they may be dysregulated in various types of cancer. The present study demonstrated that miR-144 and GATA4 were downregulated in GC tissues and cell lines and suggested that this may be due to hypermethylation. Additionally, miR-144 and GATA4 had synergistic effects on GC cells by repressing cell proliferation and inducing cell cycle arrest and apoptosis. The results of bioinformatics and a luciferase reporter assay indicated that cyclooxygenase-2 (COX-2) is a direct target of miR-144 and that miR-144 negatively regulated the expression of COX-2, which inhibits the viability of GC cells. GATA4 also induced a similar effect on COX-2. Taken together, the results of the present study may improve understanding of the underlying mechanism of miR-144 and GATA4 in GC.

Biomarker significance of plasma and tumor miR-21, miR-221, and miR-106a in osteosarcoma

Osteosarcoma is the most common malignant bone tumor in children and young adults. Despite the use of surgery and multi-agent chemotherapy, osteosarcoma patients who have a poor response to chemotherapy or develop relapses have a dismal outcome. Identification of biomarkers for active disease may help to monitor tumor burden, detect early relapses, and predict prognosis in these patients. In this study, we examined whether circulating miRNAs can be used as biomarkers in osteosarcoma patients. We performed genome-wide miRNA profiling on a discovery cohort of osteosarcoma and control plasma samples. A total of 56 miRNAs were upregulated and 164 miRNAs were downregulated in osteosarcoma samples when compared to control plasma samples. miR-21, miR-221 and miR-106a were selected for further validation based on their known biological importance. We showed that all three circulating miRNAs were expressed significantly higher in osteosarcoma samples than normal samples in an independent cohort obtained from the Children's Oncology Group. Furthermore, we demonstrated that miR-21 was expressed significantly higher in osteosarcoma tumors compared with normal bone controls. More importantly, lower expressions of miR-21 and miR-221, but not miR-106a, significantly correlated with a poor outcome. In conclusion, our results indicate that miR-21, miR-221 and miR-106a were elevated in the circulation of osteosarcoma patients, whereas tumor expressions of miR-21 and miR-221 are prognostically significant. Further investigation of these miRNAs may lead to a better prognostic method and potential miRNA therapeutics for osteosarcoma.

MicroRNA-421 promotes the proliferation and metastasis of gastric cancer cells by targeting claudin-11

The present study aimed to evaluate the expression of microRNA (miR)-421 in gastric cancer and to investigate its biological function and underlying mechanism of action in the development of gastric cancer. The expression of miR-421 was measured in 60 pairs of clinically removed gastric cancer tissues and matched adjacent normal gastric tissues by reverse transcription-quantitative polymerase chain reaction. In addition, following transfection with an miR-421 inhibitor to suppress the expression of miR-421, the proliferation, migration and cell cycle distribution of human gastric carcinoma MKN28/MKN74 cells were determined by cell counting, Transwell and flow cytometry assays. The target gene of miR-421 was also predicted using bioinformatic analysis and verified by dual-luciferase reporter gene assay and western blot analysis. Furthermore, overexpression of the miR-421 target protein was induced in MKN28/MKN74 cells to determine its function. It was observed that miR-421 was significantly upregulated in gastric cancer tissues and that the expression of miR-421 was associated with lymph node metastasis and the clinical stage of gastric cancer (all P<0.05). Claudin11 (CLDN11) was predicted and verified as a direct target of miR-421. In vitro experiments demonstrated that inhibition of miR-421 expression suppressed the proliferation and metastasis of MKN28/MKN74 cells and induced G1/S-phase cell cycle arrest (all P<0.05). Analagous results were observed in MKN28/MKN74 cells following overexpression of the CLDN11 protein. Collectively, these data suggest that miR-421 may promote the proliferation, invasion and metastasis of gastric cancer by inhibiting the expression of CLDN11.