Predictive power of circulating miRNAs in detecting colorectal cancer

Diagnostic Potential of Exosomal microRNAs in Colorectal Cancer

Background: Despite the significance of colonoscopy for early diagnosis of colorectal adenocarcinoma (CRC), population-wide screening remains challenging, mainly because of low acceptance rates. Herein, exosomal (exo-miR) and free circulating microRNA (c-miR) may be used as liquid biopsies in CRC to identify individuals at risk. Direct comparison of both compartments has shown inconclusive results, which is why we directly compared a panel of 10 microRNAs in this entity. Methods: Exo-miR and c-miR levels were measured using real-time quantitative PCR after isolation from serum specimens in a cohort of 69 patients. Furthermore, results were compared to established tumor markers CEA and CA 19-9. Results: Direct comparison of exo- and c-miR biopsy results showed significantly higher microRNA levels in the exosomal compartment (p < 0.001). Exo-Let7, exo-miR-16 and exo-miR-23 significantly differed between CRC and healthy controls (all p < 0.05), while no c-miR showed this potential. Sensitivity and specificity can be further enhanced using combinations of multiple exosomal miRNAs. Conclusions: Exosomal microRNA should be considered as a promising biomarker in CRC for future studies. Nonetheless, results may show interference with common comorbidities, which must be taken into account in future studies.

Novel Diagnostic Biomarkers in Colorectal Cancer

Colorectal cancer (CRC) is still a leading cause of cancer death worldwide. Less than half of cases are diagnosed when the cancer is locally advanced. CRC is a heterogenous disease associated with a number of genetic or somatic mutations. Diagnostic markers are used for risk stratification and early detection, which might prolong overall survival. Nowadays, the widespread use of semi-invasive endoscopic methods and feacal blood tests characterised by suboptimal accuracy of diagnostic results has led to the detection of cases at later stages. New molecular noninvasive tests based on the detection of CRC alterations seem to be more sensitive and specific then the current methods. Therefore, research aiming at identifying molecular markers, such as DNA, RNA and proteins, would improve survival rates and contribute to the development of personalized medicine. The identification of “ideal” diagnostic biomarkers, having high sensitivity and specificity, being safe, cheap and easy to measure, remains a challenge. The purpose of this review is to discuss recent advances in novel diagnostic biomarkers for tumor tissue, blood and stool samples in CRC patients.

The value of microRNAs as the novel biomarkers for colorectal cancer diagnosis: A meta-analysis

BACKGROUND

Numerous studies have reported that microRNAs (miRNAs) hold great potential as the biomarkers for colorectal cancer (CRC). However, inconsistent results have made it challenging to evaluate their diagnostic performance. Thus, the aim of this meta-analysis was to systematically assess the pooled efficacy of miRNAs for CRC diagnosis.

METHODS

A search for eligible studies up to October 30, 2019 was conducted using PubMed, Web of Science and EMBASE databases. A random-effects model was used to evaluate the pooled sensitivity and specificity. The summary receiver operator characteristic (SROC) curve and area under the curve (AUC) were calculated to assess the overall diagnostic efficacy.

RESULTS

A total of 3258 CRC patients and 2683 healthy controls were identified in 35 included studies. The overall diagnostic accuracy was as follows: sensitivity, 0.80 [95 % confidence interval (CI) 0.75-0.83]; specificity, 0.80 (95 % CI, 0.75-0.84); positive likelihood ratio (PLR), 4.0 (95 % CI, 3.2-5.0); negative likelihood ratio (NLR), 0.26 (95 % CI, 0.21-0.31); diagnostic odds ratio (DOR), 16 (95 % CI, 11-23); and AUC, 0.87 (95 % CI, 0.83-0.89).

CONCLUSION

The results indicated that miRNAs, particularly serum-derived miRNAs, can serve as the powerful and promising biomarkers for early CRC screening.

Serum patterns of mir-23a and mir-181b in irritable bowel syndrome and colorectal cancer - A pilot study

Emerging evidence demonstrates that microRNAs (miRNAs) could serve as reliable biomarkers of inflammation and oncogenesis. The aim of this study was to determine whether miR-23a and miR-181b were suitable as biomarkers of irritable bowel syndrome (IBS) and colorectal cancer (CRC). Forty patients with IBS (29 females, 11 males), 33 with CRC (14 females, 19 males), and 33 healthy controls (17 females, 16 males) were prospectively included. Serum levels of miRNAs were evaluated by quantitative real-time PCR. The serum levels of miR-23a and miR-181b were significantly higher in the IBS group (p = 0.0009 and 0.004, respectively) and CRC group (p = 0.002 and 0.029, respectively) than in the control group. Serum levels of miR-23a and miR-181b were upregulated in CRC vs. IBS, but the differences did not reach statistical significance (p = 0.169 and 0.179, respectively). The miRNet and Reactome databases identified phosphatase and tensin homolog as a major common pathway, indicating inflammation as a central hallmark. Although miRNAs could serve as reliable biomarkers in clinical practice, future studies are needed to establish appropriate cut-off limits.

Circulating molecular biomarkers for screening or early diagnosis of colorectal cancer: which is ready for prime time?

According to recent statistics, colorectal cancer (CRC) is a frequent disease, the second most frequent malignancy in women and the third most common malignant disease in men, respectively. Although reinforced emphasis on CRC screening by means of immunochemical fecal occult blood test, colonoscopy or sigmoidoscopy has contributed to decrease cancer-related deaths, alternative diagnostic tests would be needed for establishing earlier and more potentially effective treatments. Innovative diagnostic techniques have recently emerged, some of which hold promises for screening and/or early CRC detection. Recent evidence suggests that the so-called "liquid biopsy", conventionally defined as detection and quantification of circulating tumor cells (CTCs) and cancer-related nucleic acids in peripheral blood, may allow earlier diagnosis of CRC combined with lower invasiveness and less patient inconvenience, higher throughput, faster turnaround time, inferior usage of healthcare resources and relatively low cost. Encouraging data have emerged from trials based on CTCs detection, though the sensitivity of the current diagnostic techniques is still perhaps insufficient for enabling early CRC diagnosis. Among the various biomarkers that can be detected with liquid biopsy, SEPT9 methylation displays good diagnostic performance and relatively high cancer detection rate (between 57-64% in patients with CRC stages 0-I), which would make this test a promising tool for population screening, alone or in combination with other conventional diagnostic investigations. Encouraging evidence has also been recently published for BCAT1/IKZF1 methylation. Regarding microRNA (miRNAs), the available evidence highlights that the combination of some of these biomarkers rather than the assessment of a single miRNA alone would enable efficient identification of early CRCs, though widespread clinical application is still challenged by a number of preanalytical, analytical and clinical issues.

4-Acetyl-Antroquinonol B Suppresses SOD2-Enhanced Cancer Stem Cell-Like Phenotypes and Chemoresistance of Colorectal Cancer Cells by Inducing hsa-miR-324 re-Expression

Background: Colorectal cancer (CRC) remains a leading cause of cancer-related morbidity and mortality in both sexes globally. This is not unconnected with the heterogeneity and plasticity of CRC stem cells (CRC-SCs) which stealthily exploit the niche-related and (epi)genetic factors to facilitate metastasis, chemoresistance, tumor recurrence, and disease progression. Despite the accumulating evidence of the role of dysregulated microRNAs in malignancies, the therapeutic efficacy of pharmacological-targeting of CRC-SC-associated microRNAs is relatively under-explored. Experimental approach: In this present study, we employed relatively new bioinformatics approaches, analyses of microarray data, Western blot, real-time polymerase chain reaction (RT-PCR), and functional assays to show that hsa-miR-324-5p expression is significantly suppressed in CRC cells, and inversely correlates with the aberrant expression of SOD2. Results: This converse hsa-miR-324-5p/SOD2 relationship is associated with enhanced oncogenicity, which is effectively inhibited by 4-acetylantroquinonol B (4-AAQB), as evidenced by inhibited cell viability and proliferation, as well as attenuated migration, invasion, and clonogenicity in 4-AAQB-treated DLD1 and HCT116 cells. Interestingly, 4-AAQB did not affect the viability and proliferation of normal colon cells. We also showed that 4-AAQB-induced re-expression of hsa-miR-324-5p, akin to short-interfering RNA, reduced SOD2 expression, correlates with the concurrent down-regulation of SOD2, N-cadherin, vimentin, c-Myc, and BcL-xL2, with concomitant up-regulation of E-cadherin and BAX2 proteins. Enhanced expression of hsa-miR-324-5p in the CRC cells suppressed their tumorigenicity in vitro and in vivo. Additionally, 4-AAQB synergistically potentiates the FOLFOX (folinate (leucovorin), fluorouracil (5FU), and oxaliplatin) anticancer effect by eliciting the re-expression of SOD2-suppressed hsa-miR-324, and inhibiting SOD2-mediated tumorigenicity. Conclusion: Our findings highlight the pre-clinical anti-CSC efficacy of 4-AAQB, with or without FOLFOX in CRC, and suggest a potential novel therapeutic strategy for CRC patients.

The liquid biopsy in the management of colorectal cancer patients: Current applications and future scenarios

The term liquid biopsy refers to the analysis of biomarkers in any body fluid, including blood, urine and cerebrospinal fluid. In cancer, liquid biopsy testing allows the analysis of tumor-derived DNA, RNA, miRNA and proteins that can be either cell-free or contained in circulating tumor cells (CTC), extracellular vesicles (EVs) or platelets. A number of studies suggest that liquid biopsy testing could have a relevant role in the management of colorectal cancer (CRC) patients at different stages of the disease. Analysis of cell-free DNA (cfDNA), CTC and/or miRNA can provide relevant information for the early diagnosis of CRC and the identification of minimal residual disease and, more generally, the evaluation of the risk of recurrence in early CRC patients. In addition, liquid biopsy testing might allow the assessment of prognostic and predictive biomarkers in metastatic CRC patients, and the monitoring of the response to treatment and of the clonal evolution of the disease. While a number of elegant studies have shown the potential of liquid biopsy in CRC, the possibility to use this approach in the daily clinical practice is still limited. The use of non-standardized methods, the small cohorts of patients analyzed, the lack of demonstration of a clear clinical benefit are the main limitations of the studies with liquid biopsy in CRC reported up to now. The potential of this approach and the steps that need still to be taken to translate these preliminary findings in the clinic are discussed in this review.

The clinical role of microRNA-21 as a promising biomarker in the diagnosis and prognosis of colorectal cancer: a systematic review and meta-analysis

This systematic analysis aimed to investigate the value of microRNA-21 (miR-21) in colorectal cancer for multiple purposes, including diagnosis and prognosis, as well as its predictive power in combination biomarkers. Fifty-seven eligible studies were included in our meta-analysis, including 25 studies for diagnostic meta-analysis and 32 for prognostic meta-analysis. For the diagnostic meta-analysis of miR-21 alone, the overall pooled results for sensitivity, specificity, and area under the curve (AUC) were 0.64 (95% CI: 0.53-0.74), 0.85 (0.79-0.90), and 0.85 (0.81-0.87), respectively. Circulating samples presented corresponding values of 0.72 (0.63-0.79), 0.84 (0.78-0.89), and 0.86 (0.83-0.89), respectively. For the diagnostic meta-analysis of miR-21-related combination biomarkers, the above three parameters were 0.79 (0.69-0.86), 0.79 (0.68-0.87), and 0.86 (0.83-0.89), respectively. Notably, subgroup analysis suggested that miRNA combination markers in circulation exhibited high predictive power, with sensitivity of 0.85 (0.70-0.93), specificity of 0.86 (0.77-0.92), and AUC of 0.92 (0.89-0.94). For the prognostic meta-analysis, patients with higher expression of miR-21 had significant shorter disease-free survival [DFS; pooled hazard ratio (HR): 1.60; 95% CI: 1.20-2.15] and overall survival (OS; 1.54; 1.27-1.86). The combined HR in tissues for DFS and OS were 1.76 (1.31-2.36) and 1.58 (1.30-1.93), respectively. Our comprehensive systematic review revealed that circulating miR-21 may be suitable as a diagnostic biomarker, while tissue miR-21 could be a prognostic marker for colorectal cancer. In addition, miRNA combination biomarkers may provide a new approach for clinical application.

Diagnostic significance of microRNAs as novel biomarkers for bladder cancer: a meta-analysis of ten articles

BACKGROUND

Previous studies have revealed the importance of microRNAs' (miRNAs) function as biomarkers in diagnosing human bladder cancer (BC). However, the results are discordant. Consequently, the possibility of miRNAs to be BC biomarkers was summarized in this meta-analysis.

METHODS

In this study, the relevant articles were systematically searched from CBM, PubMed, EMBASE, and Chinese National Knowledge Infrastructure (CNKI). The bivariate model was used to calculate the pooled diagnostic parameters and summary receiver operator characteristic (SROC) curve in this meta-analysis, thereby estimating the whole predictive performance. STATA software was used during the whole analysis.

RESULTS

Thirty-one studies from 10 articles, including 1556 cases and 1347 controls, were explored in this meta-analysis. In short, the pooled sensitivity, area under the SROC curve, specificity, positive likelihood ratio, diagnostic odds ratio, and negative likelihood ratio were 0.72 (95%CI 0.66-0.76), 0.80 (0.77-0.84), 0.76 (0.71-0.81), 3.0 (2.4-3.8), 8 (5.0-12.0), and 0.37 (0.30-0.46) respectively. Additionally, sub-group and meta-regression analyses revealed that there were significant differences between ethnicity, miRNA profiling, and specimen sub-groups. These results suggested that Asian population-based studies, multiple-miRNA profiling, and blood-based assays might yield a higher diagnostic accuracy than their counterparts.

CONCLUSIONS

This meta-analysis demonstrated that miRNAs, particularly multiple miRNAs in the blood, might be novel, useful biomarkers with relatively high sensitivity and specificity and can be used for the diagnosis of BC. However, further prospective studies with more samples should be performed for further validation.

Circulating cell-free microRNAs as clinical cancer biomarkers

MicroRNAs (miRNAs) are non-coding small RNAs that are master regulators of genic expression and consequently of many cellular processes. But their expression is often deregulated in human tumors leading to cancer development. Recently miRNAs were discovered in body fluids (serum, plasma and others) and their levels have often been reported to be altered in patients. Circulating miRNAs became one of the most promising biomarkers in oncology for early diagnosis, prognosis and therapeutic response prediction. Here we describe the origins and roles of miRNAs, and summarize the most recent studies focusing on their usefulness as cancer biomarkers in lung, breast, colon, prostate, ovary cancers and melanoma. Lastly, we describe the main methodologies related to miRNA detection, which should be standardized for their use in clinical practice.

Epigenetic silencing of miR-181b contributes to tumorigenicity in colorectal cancer by targeting RASSF1A

Aberrant microRNA expression is common in colorectal cancer and DNA methylation is believed to be responsible for this alteration. In this study, we performed evaluation in vivo and in vitro to determine the role of miR-181b as a potential diagnostic and prognostic biomarker in colorectal cancer. Ninety-seven pairs of colorectal cancer tissues and adjacent normal tissues were collected. The expression level and methylation status of miR-181b was determined in tissue samples and multiple colorectal cancer cell lines. RASSF1A, a predicted target gene of miR-181b, was investigated in vitro. Further mechanistic explorations were conducted. It was found that miR-181b expression was frequently downregulated in cancer samples. This lower expression level resulted from higher hypermethylation in cancer tissue and was closely related to TNM stage. Following artificial synthesis of miR-181b stimulation, colorectal cancer cell proliferation was greatly inhibited in CRC cells while apoptosis percentage markedly increased. miR-181b achieved the tumor suppressive effects via direct targeting of the RASSF1A gene. This study indicated the clinical significance of miR-181b and the influence of miR-181b promoter region in epigenetic silencing of tumorigenicity in colorectal cancer, and implied the possible usage of miR-181b as a diagnostic and prognostic biomarker in colorectal cancer.

Colorectal cancer characterization and therapeutic target prediction based on microRNA expression profile

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and a major cause of cancer death. However, the molecular mechanisms underlying CRC initiation, growth and metastasis are poorly understood. In this study, based on our previous work for comprehensively analyzing miRNA sequencing data, we examined a series of colorectal cancer microRNAs expression profiles data. Results show that all these CRC samples share the same four pathways including TGF-beta signaling pathway, which is important in colorectal carcinogenesis. Twenty-one microRNAs that evolved in the four overlapped pathways were then discovered. Further analysis selected miR-21 as an important regulator for CRC through TGF-beta pathways. This study develops methods for discovering tumor specific miRNA cluster as biomarker and for screening new cancer therapy targets based on miRNA sequencing.