Serum microRNA panel as biomarkers for early diagnosis of colorectal adenocarcinoma

Extracellular MicroRNA in liquid biopsy: applicability in cancer diagnosis and prevention

One of the goals of contemporary cancer research is the development of new markers that facilitate earlier and non-invasive diagnosis. MicroRNAs are non-coding RNA molecules that regulate gene expression; studies have shown that their expression levels are altered in cancer. Recently, extra-cellular microRNAs have been detected in biological fluids and studied as possible cancer markers that can be detected by noninvasive procedures. In this review, we analyze the current understanding of extracellular miRNAs based on clinical studies to establish their possible use for the prevention of the most common tumors. Despite discrepancies among different studies of the same cancers, panels of specific extracellular microRNAs are emerging as a new tool for the secondary (selection of high-risk individuals to undergo screening) and tertiary (relapse) prevention of cancer.

miR-422a is an independent prognostic factor and functions as a potential tumor suppressor in colorectal cancer

AIM: To determine the expression of miR-422a in colorectal cancer (CRC) tissues and to further explore the prognostic value and function of miR-422a in CRC carcinogenesis.

METHODS: miR-422a expression was analyzed in 102 CRC tissues and paired normal mucosa adjacent to carcinoma by quantitative real-time PCR. The relationship of miR-422a expression with clinicopathological parameters was also analyzed. Kaplan-Meier analysis and Cox multivariate analysis were performed to estimate the potential role of miR-422a. Cell proliferation, migration, and invasion were used for in vitro functional analysis of miR-422a.

RESULTS: The levels of miR-422a were dramatically reduced in CRC tissues compared with normal mucosa (P < 0.05), and significantly correlated with local invasion (P = 0.004) and lymph node metastasis (P < 0.001). Kaplan-Meier survival and Cox regression multivariate analyses revealed that miR-422a expression (HR = 0.568, P = 0.015) and clinical TNM stage (HR = 2.942, P = 0.003) were independent prognostic factors for overall survival in CRC patients. Furthermore, in vitro experiments showed that overexpression of miR-422a inhibited the proliferation, migration, and invasion of SW480 and HT-29 cells.

CONCLUSION: Down-regulation of miR-422a may serve as an independent prognosis factor in CRC. MiR-422a functions as a tumor suppressor and regulates progression of CRC.

New Concepts in Cancer Biomarkers: Circulating miRNAs in Liquid Biopsies

The effective and efficient management of cancer patients relies upon early diagnosis and/or the monitoring of treatment, something that is often difficult to achieve using standard tissue biopsy techniques. Biological fluids such as blood hold great possibilities as a source of non-invasive cancer biomarkers that can act as surrogate markers to biopsy-based sampling. The non-invasive nature of these “liquid biopsies” ultimately means that cancer detection may be earlier and that the ability to monitor disease progression and/or treatment response represents a paradigm shift in the treatment of cancer patients. Below, we review one of the most promising classes of circulating cancer biomarkers: microRNAs (miRNAs). In particular, we will consider their history, the controversy surrounding their origin and biology, and, most importantly, the hurdles that remain to be overcome if they are really to become part of future clinical practice.

Diverse human extracellular RNAs are widely detected in human plasma

There is growing appreciation for the importance of non-protein-coding genes in development and disease. Although much is known about microRNAs, limitations in bioinformatic analyses of RNA sequencing have precluded broad assessment of other forms of small-RNAs in humans. By analysing sequencing data from plasma-derived RNA from 40 individuals, here we identified over a thousand human extracellular RNAs including microRNAs, piwi-interacting RNA (piRNA), and small nucleolar RNAs. Using a targeted quantitative PCR with reverse transcription approach in an additional 2,763 individuals, we characterized almost 500 of the most abundant extracellular transcripts including microRNAs, piRNAs and small nucleolar RNAs. The presence in plasma of many non-microRNA small-RNAs was confirmed in an independent cohort. We present comprehensive data to demonstrate the broad and consistent detection of diverse classes of circulating non-cellular small-RNAs from a large population.

Extracellular miRNAs are present in a variety of bodily fluids. Here, Freedman et al. analysed plasma-derived RNA by RNA-seq from 40 people followed by targeted RT-qPCR in an additional 2,763 people, and report over 1,000 extracellular RNAs including microRNAs, piwi-interacting RNA and small nucleolar RNAs.

Prognostic microRNA signatures derived from The Cancer Genome Atlas for head and neck squamous cell carcinomas

Identification of novel prognostic biomarkers typically requires a large dataset which provides sufficient statistical power for discovery research. To this end, we took advantage of the high‐throughput data from The Cancer Genome Atlas (TCGA) to identify a set of prognostic biomarkers in head and neck squamous cell carcinomas (HNSCC) including oropharyngeal squamous cell carcinoma (OPSCC) and other subtypes. In this study, we analyzed miRNA‐seq data obtained from TCGA patients to identify prognostic biomarkers for OPSCC. The identified miRNAs were further tested with an independent cohort. miRNA‐seq data from TCGA was also analyzed to identify prognostic miRNAs in oral cavity squamous cell carcinoma (OSCC) and laryngeal squamous cell carcinoma (LSCC). Our study identified that miR‐193b‐3p and miR‐455‐5p were positively associated with survival, and miR‐92a‐3p and miR‐497‐5p were negatively associated with survival in OPSCC. A combined expression signature of these four miRNAs was prognostic of overall survival in OPSCC, and more importantly, this signature was validated in an independent OPSCC cohort. Furthermore, we identified four miRNAs each in OSCC and LSCC that were prognostic of survival, and combined signatures were specific for subtypes of HNSCC. A robust 4‐miRNA prognostic signature in OPSCC, as well as prognostic signatures in other subtypes of HNSCC, was developed using sequencing data from TCGA as the primary source. This demonstrates the power of using TCGA as a potential resource to develop prognostic tools for improving individualized patient care.

miR‑19a‑3p targets PMEPA1 and induces prostate cancer cell proliferation, migration and invasion

Prostate cancer (PCa) is one of the most common malignant tumors in men. Studies have observed that microRNA (miR)‑19a‑3p expression levels are downregulated in several types of cancer, and yet the biological function and its underlying mechanisms in the pathogenesis of PCa remain unclear. In the current study, the expression pattern of miR‑19a‑3p in PCa tissues and cell lines was detected by reverse transcription‑quantitative polymerase chain reaction. The proliferative, migratory and invasive capacity of PCa cells were determined using EdU and Transwell assays following transfection with miR‑19a‑3p mimics. Additionally, the current study investigated the biological impact and regulation of prostate transmembrane protein androgen induced 1 (PMEPA1) in PCa cells by transfection with PMEPA1 small interfering (si)RNA. It was observed that miR‑19a‑3p was upregulated in PCa tissue samples and cell lines in vitro. Functional analysis also confirmed that miR‑19a‑3p overexpression promoted the proliferation, migration and invasion of PCa cells. Furthermore, PMEPA1 was identified as a direct target of miR‑19a‑3p, and siRNA knockdown of PMEPA1 resulted in increased proliferation, migration and invasion of PCa cells, which partially accounts for the effect of miR‑19a‑3p in tumor metastasis. In conclusion, the findings of the present study suggest that the upregulation of miR‑19a‑3p expression levels contributes to tumor progression and that one of its underlying mechanisms involves inhibition of PMEPA1 expression.

MicroRNAs in colorectal carcinoma--from pathogenesis to therapy

Background

Acting as inflammatory mediators, tumor oncogenes or suppressors, microRNAs are involved in cell survival, death, epithelial–mesenchymal transition and metastasis, etc. Investigating the communication between microRNAs and tumorigenesis is critical to our understanding of the pathogenesis of multiple disease states.

Main body

Currently, colorectal carcinoma (CRC), one of the most common malignancies worldwide, has a poor prognosis due to lack of an effective therapeutic option. Increasing evidence has identified altered profiles and regulatory potential of microRNAs in conditions related to environmentally-caused colorectal inflammation and colitis-associated cancer. Many studies have shed light on a more thorough understanding of the function and distribution of microRNAs in CRC initiation and emergence. However, the molecular mechanisms by which microRNAs modulate cellular processes still need to be further elucidated and may offer a foundation for evaluating microRNA-based therapeutic potential for CRC in both animal models and clinical trials.

Conclusion

In this review, the roles and mechanisms of microRNAs involved in CRC from pathogenesis to therapy are summarized and discussed, which may provide more useful hints for CRC prevention and therapy.

Mismatch Repair and Colon Cancer: Mechanisms and Therapies Explored

Colorectal cancer (CRC) remains one of the most prevalent cancers worldwide. In sporadic CRC, mutations frequently occur in the DNA mismatch repair (MMR) pathway. In addition, germline MMR mutations have been linked to Lynch syndrome, the most common form of hereditary CRC. Although genetic mutations, diet, inflammation, and the gut microbiota can influence CRC, it is unclear how MMR deficiency relates to these factors to modulate disease. In this review, the association of MMR to the etiology of CRC is examined, particularly in the context of microRNAs (miRNAs), inflammation, and the microbiome. We also discuss the most current targeted therapies, methods of prevention, and molecular biomarkers against MMR-deficient CRC, all of which are encouraging advancements in the field.

A Comprehensive Meta-Analysis of MicroRNAs for Predicting Colorectal Cancer

Colorectal cancer (CRC) has been defined as a common malignancy due to its prevailing incidence in both males and females. Recently, the intrinsic value of microRNAs (miRNAs) with respect to early cancer diagnosis has been contentious as the diagnostic accuracy of miRNAs significantly varied across different studies. As a result of this, this pioneer meta-analysis was proposed to address this issue. Qualified studies were obtained through electronic systematical searching in Medline, Embase, and PubMed. On the basis of the random-effects model, we calculated the pooled sensitivity (SEN), specificity (SPE), and area under the receiver operating characteristics curve (AUC) to assess the diagnostic accuracy of miRNAs. Subgroup analysis and meta-regression were implemented to determine how different confounding factors affect the overall diagnostic accuracy which were considered important sources of heterogeneity. All the statistical analyses were conducted with R 3.2.1 software. We incorporated 103 studies from 36 articles with a total of 3124 CRC patients and 2579 healthy individuals. MiRNAs have a good performance with the following pooled estimates: SEN = 0.769 (95% CI = 0.733-0.802), SPE = 0.806 (95% CI = 0.781-0.829), AUC = 0.857, and partial AUC = 0.773. As suggested by subgroup analyses and meta-regression, multiple miRNAs appeared to be more favorable than single miRNA (AUC: 0.918 > 0.813, partial AUC: 0.848 > 0.701, sensitivity = 0.853 > 0.718, specificity = 0.860 > 0.772). Compared with samples of plasma, blood, tissue, and feces, miRNA obtained from serum samples were more powerful for detecting CRC particularly in Asian. Our study provided exclusive evidence that multiple miRNAs extracted from serum samples had superior diagnostic performance over single miRNA for screening CRC. Therefore, this approach that is characterized by high specificity and noninvasive nature may assist in early diagnosis of CRC particularly in Asian.

MicroRNAs as growth regulators, their function and biomarker status in colorectal cancer

Gene expression is in part regulated by microRNAs (miRNAs). This review summarizes the current knowledge of miRNAs in colorectal cancer (CRC); their role as growth regulators, the mechanisms that regulate the miRNAs themselves and the potential of miRNAs as biomarkers. Although thousands of tissue samples and bodily fluids from CRC patients have been investigated for biomarker potential of miRNAs (>160 papers presented in a comprehensive tables), none single miRNA nor miRNA expression signatures are in clinical use for this disease. More than 500 miRNA-target pairs have been identified in CRC and we discuss how these regulatory nodes interconnect and affect signaling pathways in CRC progression.

Clinical role of circulating miR-223 as a novel biomarker in early diagnosis of cancer patients

BACKGROUND

Current diagnostic procedures of cancers are invasive and non-specific. MicroRNAs (miRNAs) have become promising molecular markers for gastric cancer (GC) predication. However, there have been inconsistencies in the literature regarding the suitability of circulating miRNAs for early detection of cancers.

METHODS

We performed a comprehensive meta-analysis to integrate an evaluation index for diagnostic accuracy of miR-223 in diagnosing cancer patients. Furthermore, we conducted an independent validation set of 50 gastric cancer patients and 50 healthy controls comparing miR-223 expression. We also analyzed miR-223 expression in vitro.

RESULTS

A total of 11 studies met the inclusion criteria and therefore included in this meta-analysis. We found that miR-223 yielded a pooled area under ROC curve (AUC) of 0.89 (sensitivity: 81%, specificity: 84%) in discriminating cancer from controls. In our validation test, plasma miR-223 levels in GC patients were significantly higher than that in healthy controls (P<0.01). ROC curve analysis showed that AUC was 0.812 with a sensitivity of 70% and specificity of 80%. Moreover, the expression trend of miR-223 in plasma samples was in accordance with that of tissue and cell samples.

CONCLUSION

Current evidences suggested that plasma miR-223 could be a reliable and non-invasive biomarker for cancer diagnosis. Further large-scale prospective studies are necessary to validate their potential applicability in human cancer diagnosis.

Hsa-miR-19a is associated with lymph metastasis and mediates the TNF-α induced epithelial-to-mesenchymal transition in colorectal cancer

Lymph node metastasis is an important factor determining the outcome of colorectal cancer. Although epithelial-to-mesenchymal transition (EMT), TNF-α and microRNA (miRNA) have been found to play important roles in lymph node metastasis, the underlying molecular mechanism remains unclear. Here we reported that high expression of microRNA-19a (miR-19a) was associated with lymph node metastasis and played an important role in TNF-α-induced EMT in colorectal cancer (CRC) cells. We analyzed miR-19a expression in surgical tissue specimens from 11 CRC patients and 275 formalin-fixed, paraffin-embedded CRC patients. We found that miR-19a was up-regulated in CRC tissues and high expression of miR-19a was significantly associated with lymph node metastasis. We further analyzed miR-19a lymph node metastasis signature in an external validation cohort of 311 CRC cases of the TCGA. MiR-19a was found to be significantly associated with lymph node metastasis in rectal cancer. In vitro, we showed that overexpression of miR-19a in human CRC cell lines promoted cell invasion and EMT. Furthermore, miR-19a was up-regulated by TNF-α and miR-19a was required for TNF-α-induced EMT and metastasis in CRC cells. Collectively, miR-19a played an important role in mediating EMT and metastatic behavior in CRC. It may serve as a potential marker of lymph node metastasis.

Upregulation of nucleostemin in colorectal cancer and its effects on cell malignancy

Objective

Nucleostemin (NS) is a new protein localized in the nucleolus of most stem cells and tumor cells, which regulates their self-renewal and cell cycle progression. The aim of this study was to investigate the expression of NS in colorectal cancer (CRC) and the effects of NS knockdown in the Sw620 cell line to provide basis for clinical target therapy.

Methods

NS expression in 372 patients with CRC and 367 normal participants was assessed using immunohistochemistry. The expression level of NS gene was evaluated by polymerase chain reaction. Then, the relationship among NS expression, clinicopathological features, and prognosis was analyzed. Silencing of NS expression was achieved by using NS-specific small-interfering RNAs. The viability and growth rate of Sw620 cells were determined by proliferation and invasion assays. Cell cycle distribution of the cells was analyzed by flow cytometry.

Results

High NS expression was positively related with node metastasis, distant metastasis, and TNM stage. In Kaplan–Meier survival analysis, patients with low NS expression always had significantly longer survival time than those with high expression. Moreover, our results showed that knockdown of NS expression inhibited proliferation and viability of Sw620 cells in a time-dependent manner. Cell cycle studies revealed that NS depletion resulted in G1 cell cycle arrest at short times of transfection (24 hours), followed with apoptosis at longer times (48 hours and 72 hours), suggesting that post-G1 arrest apoptosis occurred in Sw620 cells.

Conclusion

Overall, these results point to the essential role of NS in Sw620 cells; thus, this gene might be considered a promising target for treatment of CRC.

MicroRNAs as potential drug targets for therapeutic intervention in colorectal cancer

INTRODUCTION

MicroRNAs (miRNAs) are small (19 - 22 nucleotide), non-protein-coding RNA segments that function as master regulators of hundreds of genes simultaneously in both normal and malignant cells. In colorectal cancer (CRC) miRNAs are deregulated and have critical roles in initiation and progression of CRC by interacting with various oncogenes and tumor suppressor genes including APC, KRAS and p53, or by modulating downstream signal transduction pathways. Numerous promising miRNAs have emerged as potential drug targets for therapeutic intervention and possible candidates for replacement therapy in CRC.

AREAS COVERED

In this review the authors summarize the available information on miRNAs and their role in CRC. The authors point out specific miRNAs as potential drug targets and those having a significant role in gene activation and gene silencing during the process of CRC development, to highlight their importance as possible therapeutic candidates for the treatment of CRC.

EXPERT OPINION

Targeting miRNAs provides an emerging opportunity to develop effective miRNA-based replacement therapy or antagonists to alter expression in colon cancer patient tumors. However, the biggest challenge is to overcome obstacles associated with pharmacokinetics, delivery and toxicity in order to translate the potential of miRNAs into efficacious anticancer drugs.

Exosomal microRNA in serum is a novel biomarker of recurrence in human colorectal cancer

Background:

Functional microRNAs (miRNAs) in exosomes have been recognised as potential stable biomarkers in cancers. The aim of this study is to identify specific miRNAs in exosome as serum biomarkers for the early detection of recurrence in human colorectal cancer (CRC).

Methods:

Serum samples were sequentially obtained from six patients with and without recurrent CRC. The miRNAs were purified from exosomes, and miRNA microarray analysis was performed. The miRNA expression profiles and copy number aberrations were explored using microarray and array CGH analyses in 124 CRC tissues. Then, we validated exosomal miRNAs in 2 serum sample sets (90 and 209 CRC patients) by quantitative real-time RT–PCR.

Results:

Exosomal miR-17-92a cluster expression level in serum was correlated with the recurrence of CRC. Exosomal miR-19a expression levels in serum were significantly increased in patients with CRC as compared with healthy individuals with gene amplification. The CRC patients with high exosomal miR-19a expression showed poorer prognoses than the low expression group (P<0.001).

Conclusions:

Abundant expression of exosomal miR-19a in serum was identified as a prognostic biomarker for recurrence in CRC patients.

An update on miRNAs as biological and clinical determinants in colorectal cancer: a bench-to-bedside approach

Colorectal carcinogenesis represents a sequential progression of normal colonic mucosa from adenoma to carcinoma. It has become apparent that miRNA deregulation contributes to the initiation and progression of colorectal cancer (CRC). These oncogenic or tumor-suppressive miRNAs interact with intracellular signaling networks and lead to alteration of cell proliferation, apoptosis, metastasis and even response to chemotherapeutic treatments. This article aims to review the cutting edge progress in the discovery of the role of novel mechanisms for miRNAs in the development of CRC. We will also discuss the potential use of miRNAs as biomarkers for early diagnosis and prognosis of CRC. Furthermore, with advancements in RNA delivery technology, it is anticipated that manipulation of miRNAs may offer an alternative therapy for CRC treatment.