Circulating plasma MiR-141 is a novel biomarker for metastatic colon cancer and predicts poor prognosis

A four-miRNA signature identified from genome-wide serum miRNA profiling predicts survival in patients with nasopharyngeal carcinoma

Recent findings have reported that human serum microRNAs (miRNAs) can be used as prognostic biomarkers in various cancers. We aimed to explore the prognostic value of serum miRNAs in nasopharyngeal carcinoma (NPC) patients. The level of serum miRNA was retrospectively analyzed in 512 NPC patients recruited between January 2001 and December 2006. In the discovery stage, a microarray followed by reverse transcription-quantitative polymerase chain reaction was used to identify differentially altered miRNAs in eight patients with shorter survival and eight patients with longer survival who were well matched by age, sex and clinical stage. The identified serum miRNAs were then validated in all 512 samples, which were randomly divided into a training set and a validation set. Four serum miRNAs (miR-22, miR-572, miR-638 and miR-1234) were found to be differentially altered and were used to construct a miRNA signature. Risk scores were calculated to classify the patients into high- or low-risk groups. Patients with high-risk scores had poorer overall survival [hazard ratio (HR), 2.54; 95% confidence interval (CI), 1.57-4.12; p < 0.001] and distant metastasis-free survival (HR, 3.28; 95% CI, 1.82-5.94; p < 0.001) than those with low-risk scores in the training set; these results were confirmed in the validation and combined sets. The miRNA signature and TNM stage were independent prognostic factors. The combination of the miRNA signature and TNM stage had a better prognostic value than the TNM stage or miRNA signature alone. The four-serum miRNA signature may add prognostic value to the TNM staging system and provide information for personalized therapy in NPC.

Copy number variation in hereditary non-polyposis colorectal cancer

Hereditary non-polyposis colorectal cancer (HNPCC) is the commonest form of inherited colorectal cancer (CRC) predisposition and by definition describes families which conform to the Amsterdam Criteria or reiterations thereof. In ~50% of patients adhering to the Amsterdam criteria germline variants are identified in one of four DNA Mismatch repair (MMR) genes MLH1, MSH2, MSH6 and PMS2. Loss of function of any one of these genes results in a failure to repair DNA errors occurring during replication which can be most easily observed as DNA microsatellite instability (MSI)—a hallmark feature of this disease. The remaining 50% of patients without a genetic diagnosis of disease may harbour more cryptic changes within or adjacent to MLH1, MSH2, MSH6 or PMS2 or elsewhere in the genome. We used a high density cytogenetic array to screen for deletions or duplications in a series of patients, all of whom adhered to the Amsterdam/Bethesda criteria, to determine if genomic re-arrangements could account for a proportion of patients that had been shown not to harbour causative mutations as assessed by standard diagnostic techniques. The study has revealed some associations between copy number variants (CNVs) and HNPCC mutation negative cases and further highlights difficulties associated with CNV analysis.

Diagnostic and prognostic value of circulating miR-21 for cancer: a systematic review and meta-analysis

BACKGROUND

MicroRNAs (miRNAs) have been reported to be aberrantly expressed in patients with cancer. Many studies have shown that circulating miRNAs could play potential roles as diagnostic and prognostic biomarkers of cancers. The aim of this meta-analysis is to summarize the role of circulating miR-21 as a biomarker in patients with a variety of carcinomas.

MATERIAL AND METHODS

Eligible studies were identified and assessed for quality through multiple search strategies. For diagnostic meta-analysis, the sensitivity, specificity, and other measures of miR-21 in the diagnosis of cancer were pooled using bivariate random-effects approach models. For prognostic meta-analysis, pooled hazard ratios (HRs) of circulating miR-21 for survival were calculated.

RESULTS

A total of 36 studies dealing with various carcinomas were included for the systemic review. Among them, 23 studies were finally enrolled in the global meta-analysis (17 studies for diagnosis and 6 studies for prognosis). For diagnostic meta-analysis, the overall pooled results for sensitivity, specificity, positive likelihood ratio (LRP), negative likelihood ratios (LRN) and diagnostic odds ratio (DOR) were 75.7% (95% CI: 67.1%-82.6%), 79.3% (95% CI: 74.2%-83.5%), 3.65 (95% CI: 2.83-4.70), 0.31 (95% CI: 0.22-0.43), and 11.88 (95% CI: 6.99-20.19), respectively. For prognostic meta-analysis, the pooled HR of higher miR-21 expression in circulation was 2.37 (95% CI: 1.83-3.06, P<0.001), which could significantly predict poorer survival in general carcinomas. Importantly, subgroup analysis suggested that higher expression of miR-21 correlated with worse overall survival (OS) significantly in carcinomas of digestion system (HR, 5.77 [95% CI: 2.65-12.52]).

CONCLUSIONS

Our findings suggest that circulating miR-21 may not suitable to be a diagnostic biomarker, but it has a prognostic value in patients with cancer.

Plasma microRNAs predicting clinical outcome in metastatic colorectal cancer patients receiving first-line oxaliplatin-based treatment

The conventional first-line chemotherapy for metastatic colorectal cancer (mCRC) consists of fluorouracil (5-FU) in combination with either oxaliplatin or irinotecan. We have explored microRNAs (miRNAs) in plasma as potential predictive markers to oxaliplatin-based chemotherapy. The expression of 742 miRNAs was examined in plasma samples from 24 mCRC patients (12 responders and 12 non-responders) before onset and after four cycles of 5-FU/oxaliplatin. The top differentially expressed miRNAs between responders and non-responders were selected for further analysis in a validation cohort of 150 patients. In the validation cohort, there was a significant overrepresentation of miRNAs with higher mean expression in the non-responder group than in the responder group before treatment (p < 0.002). Moreover, we found three miRNAs (miR-106a, miR-484, and miR-130b) to be significantly differentially expressed before treatment (p = 0.008, 0.008, and 0.008, respectively). All three miRNAs were upregulated in non-responders. High expression of miR-27b, miR-148a, and miR-326 were associated with decreased progression-free survival (Hazard ratios (HR) of 1.4 (95% CI 1.1-1.8, p = 0.004), 1.3 (95% CI 1.1-1.6, p = 0.007), and 1.4 (95% CI 1.1-1.8, p = 0.008), respectively). miR-326 was also associated with decreased overall survival (HR 1.5 (95% CI 1.1-2.0, p = 0.003)). There were no significantly differentially expressed miRNAs in association with clinical outcome after four cycles of chemotherapy. The present study demonstrates that plasma miRNAs analyzed before treatment may serve as non-invasive markers predicting outcome in mCRC patients treated with 5-FU and oxaliplatin-based chemotherapy.

miRNA-141, downregulated in pancreatic cancer, inhibits cell proliferation and invasion by directly targeting MAP4K4

miRNAs are associated with various types of cancer due to their ability to affect expression of genes that modulate tumorigenesis. In this study, we explored the role of miR-141 in pancreatic cancer. The analysis of clinical characteristics showed that miR-141 was significantly downregulated in tissues and cell lines of pancreatic cancer. Moreover, the decreased miR-141 level was significantly associated with tumor size and TNM stage, as well as lymph node and distant metastasis. Meanwhile, both Kaplan-Meier and multivariate survival analysis showed decreased miR-141 were associated with overall survival. Overexpression of miR-141 in pancreatic cancer cells inhibited cell proliferation, clonogenicity, and invasion; induced G1 arrest and apoptosis; and enhanced chemosensitivity. To understand how miR-141 mediates the phenotype of pancreatic cancer cells, a bioinformatics tool was used to identify MAP4K4 as a potential target of miR-141. The Dual-Luciferase reporter gene assay showed that miR-141 binds directly to the 3'-untranslated region (3'UTR) of MAP4K4 to inhibit MAP4K4 expression. Western blot and quantitative real-time PCR (qRT-PCR) analyses revealed that MAP4K4 expression was inversely correlated with miR-141 expression both in pancreatic cancer samples and cell lines. Knockdown of MAP4K4 inhibited cell proliferation, clonogenicity, and invasion, induced G1 arrest and apoptosis, and enhanced chemosensitivity. In a nude mouse xenograft model, both overexpression of miR-141 and knockdown of MAP4K4 significantly repressed pancreatic cancer cell growth. Therefore, we conclude that miR-141 targets MAP4K4, acts as a tumor suppressor in pancreatic cancer cells, and may serve as a novel therapeutic agent for miRNA-based pancreatic cancer therapy.

How microRNAs influence both hereditary and inflammatory-mediated colon cancers

MicroRNAs have emerged as important post-translational regulators of gene expression and are involved in several physiological and pathological states including the pathogenesis of human colon cancers. In regards to tumor development, microRNAs can act as oncogenes or tumor suppressors. Two hereditary predispositions (i.e., Lynch syndrome and familial adenomatous polyposis) contribute to the development of colon cancer. In addition, individuals who suffer from inflammatory bowel diseases such as Crohn's disease or ulcerative colitis have a higher risk of developing colon cancer. Here, we discuss the occurrence of the deregulated expression of microRNAs in colon cancer that arise as a result of hereditary predisposition and inflammatory bowel disease.

Prognostic implications of serum microRNA-21 in colorectal cancer

BACKGROUND AND OBJECTIVES

MicroRNAs (miRNAs) are small, noncoding RNAs that are involved in carcinogenesis through postranscriptional gene regulatory activity. Few studies have focused on the detection of miR-21 in serum rather than in tissue. The current study aimed to measure serum miR-21 expression levels and to evaluate their association with the outcome of colorectal cancer (CRC).

METHODS

Blood samples were collected from 102 CRC patients undergoing surgery with curative intent. The expression levels of miR-21 were measured using a quantitative reverse transcription polymerase chain reaction (qRT-PCR). The results were analysed to assess the relationship between serum miR-21 levels and patient survival.

RESULTS

A univariate analysis revealed that lower expression levels of serum miR-21 were associated with higher local recurrence (P = 0.025) and mortality (P = 0.029). A logistic regression analysis demonstrated that the relative overexpression of miR-21 (expression > 1) was associated with a 51% reduction in the risk of recurrence. A Cox regression analysis identified miR-21 expression as an independent predictor of survival (P = 0.048); a relative increase in miR-21 expression (>1) was associated with a 50% reduction in the risk of mortality.

CONCLUSION

The expression level of serum miR-21 correlates with the recurrence and mortality of CRC patients. Our results suggest that circulating serum miR-21 is a promising prognostic tumour marker, and they highlight the potential clinical utility of miR-21 expression as a prognostic marker for CRC prognosis.

Predicting chemotherapeutic response and toxicity in colorectal cancer

SUMMARY While treatment for colorectal cancer has evolved significantly over the past 10 years with the introduction of active chemotherapeutic agents and targeted therapies, this has been at the cost of increased toxicity for patients; and significant financial burden for governments and patients. Predicting clinical outcomes, especially given the largely elderly patient population involved, is therefore paramount. This review seeks to summarize existing data regarding the prediction of response and toxicity to chemotherapy agents currently used in the treatment of colorectal cancer.

Differential microRNA expression in renal cell carcinoma

The present study aimed to detect microRNA expression levels in the tissues and sera of patients with clear cell renal cell carcinoma (ccRCC). The association of microRNA expression with ccRCC clinical pathology was analyzed, and the potential of the microRNAs as ccRCC serum markers and the significance of their expression in the clinical diagnosis, staging, prognosis and selection of new therapeutic targets for ccRCC were discussed. Specific microRNAs were selected according to the associated literature. TaqMan quantitative polymerase chain reaction (qPCR) technology was used to determine the expression levels of selected microRNAs. miR-34a, miR-224 and miR-21 were upregulated, whereas miR-141, miR-149 and miR-429 were downregulated in the ccRCC tissues (P<0.01). The expression of miR-221 and miR-211 was not significant in the ccRCC tissues (P>0.05). miR-34a, miR-21 and miR-224 were upregulated and miR-141 was downregulated in the sera of patients with ccRCC (P<0.01), while the expression of miR-149 and miR-429 was not significant (P>0.05). The serum miR-21 expression levels were significantly correlated with the clinical staging of the patients with ccRCC (P<0.05). miR-34a, miR-21 and miR-224 are upregulated in the tissues and sera of patients with ccRCC, whereas miR-141 is downregulated. miR-21 and miR-141 are associated with ccRCC and are, thus, potential ccRCC serum markers.

MicroRNA-206 is involved in hypoxia-induced pulmonary hypertension through targeting of the HIF-1α/Fhl-1 pathway

Hypoxia-induced pulmonary hypertension (PH), which is characterized by vasoconstriction and subsequent structural remodeling of blood vessels, is an important event in chronic obstructive pulmonary disease patients and in people living at high altitudes. Hypoxia-inducible factor-1α (HIF-1α) and its regulator four-and-a-half LIM (Lin-11, Isl-1 and Mec-3) domain 1 (Fhl-1) have important roles in hypoxia-induced PH. MicroRNA-206 (miR-206) is critical for myogenesis and related diseases; however, the role of miR-206 in hypoxia-induced PH is unknown. miR-206 expression was evaluated in a hypoxic rat model and in cultured hypoxic pulmonary artery smooth muscle cells (PASMCs) using real-time quantitative PCR (RT-qPCR). HIF-1α and Fhl-1 expression were evaluated using RT-qPCR, western blotting, immunohistochemistry and immunofluorescence. The function of miR-206 was assessed by transfecting miR-206 mimics and inhibitors. Dual-luciferase reporter gene assays and western blotting were performed to validate the target genes of miR-206. siRNA targeted against Fhl-1 was used to investigate the effect of Fhl-1 on miR-206. Flow cytometry was used to detect the cell cycle phase distribution in each group of PASMCs. Significant downregulation of miR-206 in hypoxic lung tissue and PASMCs was identified, whereas HIF-1α and Fhl-1 were upregulated in these samples. The expression of miR-206 in the serum was different from that in the lung tissue. Transfection of pre-miR miR-206 in hypoxic conditions led to increased expression of HIF-1α and Fhl-1 rather than abolishing hypoxia-induced HIF-1α and Fhl-1, as was expected, and promoted the entry of cells into the S phase and enhanced PASMC proliferation. Fhl-1-targeted siRNA in PASMC prevented cell proliferation and led to an increased proportion of cells in the G1 phase without altering miR-206 expression. Bioinformatic analysis and dual-luciferase reporter gene assays revealed direct evidence for miR-206 targeting of HIF-1α. In conclusion, hypoxia-induced downregulation of miR-206 promotes PH by targeting the HIF-1α/Fhl-1 pathway in PASMCs. miR-206 could be a triggering factor of early stage of hypoxia-induced PH.

miRNA: The nemesis of gastric cancer (Review)

microRNAs (miRNAs) are a group of small non-coding RNAs that are ~22 (18 to 25) nucleotides (nt) long and have been associated with a variety of diseases, including cancer. Increasing evidence indicates that miRNAs are essential in the development, diagnosis, treatment and prognosis of a variety of tumors. The utility of miRNAs as biomarkers for diagnosis and of target molecules for the treatment of cancers is increasingly being recognized. With the discovery of circulating miRNAs, a non-invasive approach for the diagnosis and treatment of cancer has been identified. This review summarizes the role of miRNAs in the development of different tumors, as well as a variety of other biological events. Moreover, this review focuses on analyzing the function and mechanism of gastric cancer-related miRNAs and investigates the importance of circulating miRNAs in gastric cancer, as well as their origin. Finally, this review lists a number of the problems that must be solved prior to miRNAs being used as reliable non-invasive tools for the diagnosis, treatment and prognosis of gastric cancer.

Cancer diagnosis and prognosis decoded by blood-based circulating microRNA signatures

In the recent years, circulating microRNAs (miRNAs) have garnered a lot of attention and interest in the field of disease biomarkers. With characteristics such as high stability, low cost, possibility of repeated sampling and minimal invasiveness, circulating miRNAs are ideal for development into diagnostic tests. There have been many studies reported on the potential of circulating miRNAs as early detection, prognostic, and predictive biomarkers in cancer. Here, we have reviewed the application of plasma and serum miRNAs as biomarkers for cancer focusing on epithelial carcinomas [prostate, breast, lung, colorectal, and gastric cancer (GC)] and hematological malignancies (leukemia and lymphoma). We have also addressed the common challenges that need to be overcome to achieve a successful bench to bedside transition.

Epigenetics and colorectal cancer pathogenesis

Colorectal cancer (CRC) develops through a multistage process that results from the progressive accumulation of genetic mutations, and frequently as a result of mutations in the Wnt signaling pathway. However, it has become evident over the past two decades that epigenetic alterations of the chromatin, particularly the chromatin components in the promoter regions of tumor suppressors and oncogenes, play key roles in CRC pathogenesis. Epigenetic regulation is organized at multiple levels, involving primarily DNA methylation and selective histone modifications in cancer cells. Assessment of the CRC epigenome has revealed that virtually all CRCs have aberrantly methylated genes and that the average CRC methylome has thousands of abnormally methylated genes. Although relatively less is known about the patterns of specific histone modifications in CRC, selective histone modifications and resultant chromatin conformation have been shown to act, in concert with DNA methylation, to regulate gene expression to mediate CRC pathogenesis. Moreover, it is now clear that not only DNA methylation but also histone modifications are reversible processes. The increased understanding of epigenetic regulation of gene expression in the context of CRC pathogenesis has led to development of epigenetic biomarkers for CRC diagnosis and epigenetic drugs for CRC therapy.

Circulating microRNAs as biomarkers of colorectal cancer: results from a genome-wide profiling and validation study

BACKGROUND & AIMS

Circulating microRNAs (miRNAs/miRs) might be used as biomarkers for the diagnosis of cancer and other diseases. Noninvasive approaches are needed to complement and improve upon current strategies for colorectal cancer (CRC) screening. We investigated whether plasma levels of miRNA can differentiate patients with CRC from healthy individuals. We also investigated whether plasma samples from patients with premalignant neoplastic lesions, such as advanced adenomas (AAs), also had a different expression pattern of miRNAs.

METHODS

We analyzed 196 plasma samples from 123 patients newly diagnosed with sporadic colorectal neoplasia (63 with CRC and 60 with AAs) and 73 healthy individuals (controls) seen at 2 tertiary medical centers in Spain. An initial set of samples was analyzed using a genome-wide miRNA expression profiling assay (n = 61). Quantitative reverse-transcription PCR was used to validate the expression of selected miRNAs in an independent cohort (n = 135).

RESULTS

Patients with CRC or AAs had plasma miRNA expression profiles that differed significantly from those of controls. We selected a group of 13 miRNAs for validation in an independent cohort of patients; 6 (miR18a, miR19a, miR19b, miR15b, miR29a, and miR335) were confirmed to be significantly up-regulated in patients with CRC, differentiating patients with CRC from controls with area under the receiver operating characteristic curve values ranging from 0.80 (95% confidence interval [CI], 0.71-0.89) to 0.70 (95% CI, 0.59-0.80). Only miR18a was confirmed to be significantly up-regulated in patients with AAs, compared with controls; the area under the receiver operating characteristic curve value was 0.64 (95% CI, 0.52-0.75).

CONCLUSIONS

Patients with CRC have significantly different patterns of miRNA expression than healthy individuals. These patterns might be developed as biomarkers for CRC, although they have limited value in identifying patients with premalignant neoplastic lesions.

Serum miR-21 as a diagnostic and prognostic biomarker in colorectal cancer

BACKGROUND

The oncogenic microRNAs (miRNAs) miR-21 and miR-31 negatively regulate tumor-suppressor genes. Their potential as serum biomarkers has not been determined in human colorectal cancer (CRC).

METHODS

To determine whether miR-21 and miR-31 are secretory miRNAs, we screened expression in medium from 2 CRC cell lines, which was followed by serum analysis from 12 CRC patients and 12 control subjects. We validated expression of candidate miRNAs in serum samples from an independent cohort of 186 CRC patients, 60 postoperative patients, 43 advanced adenoma patients, and 53 control subjects. We analyzed miR-21 expression in 166 matched primary CRC tissues to determine whether serum miRNAs reflect expression in CRC. Patient survival analyses were performed by Kaplan-Meier analyses and Cox regression models. All statistical tests were two-sided.

RESULTS

Although miR-21 was secreted from CRC cell lines and upregulated in serum of CRC patients, no statistically significant differences were observed in serum miR-31 expression between CRC patients and control subjects. In the validation cohort, miR-21 levels were statistically significantly elevated in preoperative serum from patients with adenomas (P < .001) and CRCs (P < .001). Importantly, miR-21 expression dropped in postoperative serum from patients who underwent curative surgery (P < .001). Serum miR-21 levels robustly distinguished adenoma (area under the curve [AUC] = 0.813; 95% confidence interval [CI] = 0.691 to 0.910) and CRC (AUC = 0.919; 95% CI = 0.867 to 0.958) patients from control subjects. High miR-21 expression in serum and tissue was statistically significantly associated with tumor size, distant metastasis, and poor survival. Moreover, serum miR-21 was an independent prognostic marker for CRC (hazard ratio = 4.12; 95% CI = 1.10 to 15.4; P = .03).

CONCLUSIONS

Serum miR-21 is a promising biomarker for the early detection and prognosis of CRC.

Serum microRNAs: A new diagnostic method for colorectal cancer

Colorectal cancer (CRC) is the third most common malignant tumor worldwide, affecting over 1.23 million individuals annually. Over the past several years, the role of microRNAs (miRNAs) in CRC cells have been extensively investigated. Recently, it was discovered that extracellular miRNAs circulate in the blood of healthy individuals as well as CRC patients. Serum circulating miRNAs as novel biomarkers may be a new approach to CRC diagnosis. However, their secretory mechanism and biological function have not been fully elucidated. In this review, the main serum miRNAs used as potential diagnostic biomarkers for CRC, such as miR-92, miR-141, miR-29a, miR-21, miR-221, miR-601 and miR-760, were summarized. In addition, the mechanism of miRNA secretion from CRC cells was discussed. It is recommended that additional studies focus on the usefulness of serum miRNAs for early CRC diagnosis, prognosis and therapeutics.

Methylated DNA and microRNA in body fluids as biomarkers for cancer detection

Epigenetic alterations including DNA methylation and microRNAs (miRNAs) play important roles in the initiation and progression of human cancers. As the extensively studied epigenetic changes in tumors, DNA methylation and miRNAs are the most potential epigenetic biomarkers for cancer diagnosis. After the identification of circulating cell-free nuclear acids, increasing evidence demonstrated great potential of cell-free epigenetic biomarkers in the blood or other body fluids for cancer detection.

Identification and evaluation of plasma microRNAs for early detection of colorectal cancer

Background

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers. Circulating microRNAs (miRNAs) have been suggested as potentially promising markers for early detection of CRC. We aimed to identify and evaluate a panel of miRNAs that might be suitable for CRC early detection.

Methods

MiRNAs were profiled by TaqMan MicroRNA Array and screened for differential expression in 5 pools of plasma samples of CRC patients (N = 50) and 5 pools of neoplasm-free controls (N = 50). Additional miRNAs were selected from a literature review. Identified candidates were evaluated in independent validation samples with respect to discrimination of CRC patients (N = 80) or advanced adenoma patients (N = 50) and neoplasm-free controls (N = 194). Diagnostic performance of the panel of miRNAs was assessed by multiple logistic regression, using bootstrap analysis to correct for over-optimism.

Results

Five miRNAs identified to be differentially expressed from TaqMan MicroRNA Array (miR-29a, -106b, -133a, -342-3p, -532-3p), and seven miRNAs reported to be differentially expressed in the literature (miR-18a, -20a, -21, -92a, -143, -145, -181b) were selected for validation. Nine of the twelve miRNAs (miR-18a, -20a, -21, -29a, -92a, -106b, -133a, -143, -145) were found to be differentially expressed in CRC patients and controls in the validation samples. The optimism-corrected area under the curve was 0.745 (95% confidence interval: 0.708–0.846). None of the selected miRNAs showed significant differential expression between advanced adenoma patients and neoplasm-free controls.

Conclusion

The identified panel of miRNAs could be of potential use in the development of a multi-marker blood based test for early detection of CRC. Impact: The study underscores the high potential of plasma miRNAs for the improvement of current offers of non-invasive CRC screening.

Identification of serum microRNA profiles in colon cancer

Background:

microRNAs (miRNAs) exist in blood in an apparently stable form. We have explored whether serum miRNAs can be used as non-invasive early biomarkers of colon cancer.

Methods:

Serum samples from 30 patients with colon cancer stage IV and 10 healthy controls were examined for the expression of 375 cancer-relevant miRNAs. Based on the miRNA profile in this study, 34 selected miRNAs were measured in serum from 40 patients with stage I–II colon cancer and from 10 additional controls.

Results:

Twenty miRNAs were differentially expressed in serum from stage IV patients compared with controls (P<0.01). Unsupervised clustering revealed four subgroups; one corresponding mostly to the control group and the three others to the patient groups. Of the 34 miRNAs measured in the follow-up study of stage I–II patients, 21 showed concordant expression between stage IV and stage I–II patient. Based on the profiles of these 21 miRNAs, a supervised linear regression analysis (Partial Least Squares Regression) was performed. Using this model we correctly assigned stage I–II colon cancer patients based on miRNA profiles of stage IV patients.

Conclusion:

Serum miRNA expression profiling may be utilised in early detection of colon cancer.

Circulating miRNAs as sensitive and specific biomarkers for the diagnosis and monitoring of human diseases: promises and challenges

The regulation and modulation of gene expression has been a central focus of modern biomedical research ever since the first molecular elucidation of DNA. The cellular mechanisms by which genes are expressed and repressed hold valuable insight for maintaining tissue homeostasis or conversely provide mechanistic understanding of disease progression. Hence, the discovery of the first miRNA in humans roughly a decade ago profoundly shook the previously established dogmas of gene regulation. Since, these small RNAs of around 20 nucleotides have unquestionably influenced almost every area of medical research. This momentum has now spread to the clinical arena. Hundreds of papers have already been published shedding light on the mechanisms of action of miRNAs, their profound stability in almost every bodily fluid and relating their presence to disease state and severity of disease progression. In this review, we explore the diagnostic potential of miRNAs in the clinical laboratory with a focus on studies reporting the detection of miRNAs in blood and urine for investigation of human disease. Sensitivities, specificities, areas under the curve, group descriptions and miRNAs of interest for 69 studies covering a broad range of diseases are provided. We discuss the practicality of miRNAs in the screening, diagnosis and prognosis of a range of pathologies. Characteristics and pitfalls of miRNA detection in blood are also discussed. The topics covered here are pertinent in the design of future miRNA-based detection strategies for use in clinical biochemistry laboratory settings.

The Diagnostic and Prognostic Role of microRNA in Colorectal Cancer - a Comprehensive review

The discovery of microRNA, a group of regulatory short RNA fragments, has added a new dimension to the diagnosis and management of neoplastic diseases. Differential expression of microRNA in a unique pattern in a wide range of tumor types enables researches to develop a microRNA-based assay for source identification of metastatic disease of unknown origin. This is just one example of many microRNA-based cancer diagnostic and prognostic assays in various phases of clinical research.

Since colorectal cancer (CRC) is a phenotypic expression of multiple molecular pathways including chromosomal instability (CIN), micro-satellite instability (MIS) and CpG islands promoter hypermethylation (CIMP), there is no one-unique pattern of microRNA expression expected in this disease and indeed, there are multiple reports published, describing different patterns of microRNA expression in CRC.

The scope of this manuscript is to provide a comprehensive review of the scientific literature describing the dysregulation of and the potential role for microRNA in the management of CRC. A Pubmed search was conducted using the following MeSH terms, "microRNA" and "colorectal cancer". Of the 493 publications screened, there were 57 papers describing dysregulation of microRNA in CRC.

Circulating MicroRNAs as Biomarkers of Prostate Cancer: The State of Play

MicroRNAs are key regulators of gene expression and play critical roles in both normal physiology and pathology. Recent research has demonstrated that these molecules are present in body fluids, such as serum, plasma, and urine, and can be readily measured using a variety of techniques. More importantly, emerging evidence suggests that circulating or urine miRNAs are useful indicators of disease. Here, we consider the potential utility of such miRNAs as noninvasive biomarkers of prostate cancer, a disease that would benefit substantially from novel diagnostic and prognostic tools. The studies aimed at identifying diagnostic, prognostic, and/or predictive miRNAs for prostate cancer are summarised and reviewed. Finally, practical considerations that will influence the translation of this recent research into clinical implementation are discussed.

Blood-based miRNAs as noninvasive diagnostic and surrogative biomarkers in colorectal cancer

Few studies have assessed circulating miRNAs in the blood of colorectal cancer (CRC) patients. In the evaluated article, Kanaan et al. demonstrated that miR-21 may be a promising diagnostic plasma biomarker for CRC. They assessed miRNAs dysregulated in both tissue and blood samples from patients with CRC. A high-throughput microarray was used to first detect miRNAs deregulated in CRC compared with adjacent normal tissue. The three most upregulated and downregulated miRNAs were then measured in blood samples. Plasma miR-21 was able to correctly identify CRC with 90% specificity and sensitivity. In this article, we have considered the use of miRNAs as blood-based biomarkers for CRC.

Non-Coding RNAs: Functional Aspects and Diagnostic Utility in Oncology

Noncoding RNAs (ncRNAs) have been found to have roles in a large variety of biological processes. Recent studies indicate that ncRNAs are far more abundant and important than initially imagined, holding great promise for use in diagnostic, prognostic, and therapeutic applications. Within ncRNAs, microRNAs (miRNAs) are the most widely studied and characterized. They have been implicated in initiation and progression of a variety of human malignancies, including major pathologies such as cancers, arthritis, neurodegenerative disorders, and cardiovascular diseases. Their surprising stability in serum and other bodily fluids led to their rapid ascent as a novel class of biomarkers. For example, several properties of stable miRNAs, and perhaps other classes of ncRNAs, make them good candidate biomarkers for early cancer detection and for determining which preneoplastic lesions are likely to progress to cancer. Of particular interest is the identification of biomarker signatures, which may include traditional protein-based biomarkers, to improve risk assessment, detection, and prognosis. Here, we offer a comprehensive review of the ncRNA biomarker literature and discuss state-of-the-art technologies for their detection. Furthermore, we address the challenges present in miRNA detection and quantification, and outline future perspectives for development of next-generation biodetection assays employing multicolor alternating-laser excitation (ALEX) fluorescence spectroscopy.

Roles of exosomes and microvesicles in disease pathogenesis

A variety of cells release membrane vesicles, such as exosomes and microvesicles (MVs), that are thought to play key roles in cell-cell communication, antigen presentation, and the spread of infectious agents throughout the body. There have been considerable efforts to use MVs as diagnostic or prognostic markers because their composition is reflective of minor physiological changes. Furthermore, recent studies demonstrate that MVs derived from infected cells and tumors contribute to disease pathogenesis. This review presents an overview of the potential roles of MVs with respect to clinical diagnosis and disease pathogenesis.

Three-mode electrochemical sensing of ultralow microRNA levels

MicroRNAs (miRNAs) are an emerging class of biomarkers that are frequently deregulated in cancer cells and have shown great promise for cancer classification and prognosis. In this work, we developed a three-mode electrochemical sensor for detection and quantitation of ultralow levels of miRNAs in a wide dynamic range of measured concentrations. The sensor facilitates three detection modalities based on hybridization (H-SENS), p19 protein binding (P-SENS), and protein displacement (D-SENS). The combined three-mode sensor (HPD-SENS) identifies as low as 5 aM or 90 molecules of miRNA per 30 μL of sample without PCR amplification, and can be operated within the dynamic range from 10 aM to 1 μM. The HPD sensor is made on a commercially available gold nanoparticles-modified electrode and is suitable for analyzing multiple miRNAs on a single electrode. This three-mode sensor exhibits high selectivity and specificity and was used for sequential analysis of miR-32 and miR-122 on one electrode. In addition, the H-SENS can recognize miRNAs with different A/U and G/C content and distinguish between a fully matched miRNA and a miRNA comprising either a terminal or a middle single base mutation. Furthermore, the H- and P-SENS were successfully employed for direct detection and profiling of three endogenous miRNAs, including hsa-miR-21, hsa-miR-32, and hsa-miR-122 in human serum, and the sensor results were validated by qPCR.

An elevated serum miR-141 level in patients with bone-metastatic prostate cancer is correlated with more bone lesions

The skeleton is the most common metastatic organ in patients with prostate cancer (PCa). Non-invasive biomarkers that can facilitate the detection and monitoring of bone metastases are highly desirable. We designed this study to assess the expression patterns of serum miR-141 in patients with bone-metastatic PCa. Serum samples were collected to measure the miR-141 level in 56 patients, including six with benign prostatic hyperplasia (BPH), 20 with localized PCa and 30 with bone-metastatic PCa (10 with hormone-naive PCa, 10 with hormone-sensitive PCa and 10 with hormone-refractory PCa). A bone scan was performed for each patient with PCa to assess the number of bone lesions. The quantification of serum miR-141 levels was assayed by specific TaqMan qRT-PCR. The results showed that serum miR-141 levels were elevated in patients with bone metastasis (P<0.001). There was no statistically significant difference in the serum miR-141 levels between patients with BPH and patients with localized PCa. Using Kendall's bivariate correlation test, both the Gleason score and the number of bone-metastatic lesions were found to correlate with serum miR-141 levels (P=0.012 and P<0.001, respectively). The serum miR-141 level was found to be positively correlated with alkaline phosphatase (ALP) level in patients with skeletal metastasis, using Pearson's bivariate correlation test. No relationship was found between the serum miR-141 level and the serum prostate-specific antigen (PSA) level. We concluded that serum miR-141 levels are elevated in patients with bone-metastatic PCa and that patients with higher levels of serum miR-141 developed more bone lesions. Furthermore, serum miR-141 levels are correlated with serum ALP levels but not serum PSA levels.

Principles of microRNA involvement in human cancers

Naturally occurring microRNAs (miRNAs), small non-coding RNAs of 19 to 24 nucleotides (nt), are encoded in the genomes of invertebrates, vertebrates, and plants. miRNAs act as regulators of gene expression during development and differentiation at the transcriptional, posttranscriptional, and/or translational levels, although most target genes are still elusive. Many miRNAs are conserved in sequence between distantly related organisms, suggesting that these molecules participate in essential processes. In this review, we present principles related to the basic and translational research that has emerged in the last decade, a period that can be truly considered the “miRNA revolution” in molecular oncology. These principles include the regulation mechanism of miRNA expression, functions of miRNAs in cancers, diagnostic values and therapeutic potentials of miRNAs. Furthermore, we present a compendium of information about the main miRNAs that have been identified in the last several years as playing important roles in cancers. Also, we orient the reader to several additional reviews that may provide a deeper understanding of this new and exciting field of research.

MicroRNA and Epigenetics: Diagnostic and Therapeutic Opportunities

MicroRNAs (miRNAs) are a large family of post-transcriptional regulators of gene expression that control cellular and developmental processes by targeting messenger RNAs (mRNA). These small non-coding RNAs (ncRNAs) are aberrantly expressed in cancer, and are known to contribute to tumorigenesis and disease progression. Therapeutic strategies based on modulating miRNAs activity are emerging due to the ability of these ncRNAs to influence cellular behavior. MiRNA levels predict disease prognosis and overall patient survival, and reconstituting their basal levels has been proven to inhibit tumor growth and metastasis. Different delivery mechanisms have been tested in vivo, however many challenges need to be overcome before their utilization in the clinic. Moreover, it has been found that circulating miRNAs in body fluids have the potential to reshape cancer diagnosis and prognosis by functioning as biomarkers and indicators of progression and metastasis. These miRNAs as biofluids-based biomarkers provide an alternative strategy for early diagnosis and treatment of cancer patients.

Circulating microRNAs in serum: novel biomarkers for patients with bladder cancer?

PURPOSE

Recent studies indicate that circulating microRNAs in serum/plasma are a novel class of non-invasive biomarkers with diagnostic and prognostic information. So far, circulating microRNAs have not been analyzed in patients with bladder cancer.

METHODS

We collected serum from patients with non-muscle invasive bladder cancer (NMIBC), muscle invasive bladder cancer (MIBC) and non-malignant urological disease. Total RNA was isolated from 400 μl of serum using the mirVana PARIS Kit; the artificial cel-miR-39 was spiked-in prior to RNA isolation to control different RNA isolation efficiencies. Quantitative real-time PCR was applied to measure the levels of 22 microRNAs upregulated in BCA tissue (miR-15a, miR-18a, miR-21, miR-93, miR-96, miR-103, miR-130b, miR-135b, miR-141, miR-182, miR-183, miR-190, miR-191, miR-200b, miR-422b, miR-425, miR-449b, miR-601, miR-639, miR-644, miR-649 and miR-1233) in the marker identification cohort (NMIBC, n = 11, MIBC, n = 10; controls, n = 10). The most promising serum microRNAs were tested in a validation cohort (NMIBC, n = 65, MIBC, n = 61; controls, n = 105).

RESULTS

The RNA recovery was similar in patients with NMIBC, MIBC and control subjects. The analysis of serum microRNA levels in the marker identification cohort indicated that serum miR-141 and miR-639 levels were increased in bladder cancer patients compared to CTRL. The analysis of these miR-141 and miR-639 in the validation cohort demonstrated that microRNA levels were similar in bladder cancer patients and control subjects. Furthermore, microRNA levels were not correlated with clinicopathological parameters (pT-stage, metastasis, grading).

CONCLUSIONS

The analysis of serum miR-141 and miR-639 levels does not seem to be helpful in the diagnosis or prognosis of BCA.

Expression of miR-106a in colorectal cancer and its relation with tumor cell invasion

AIM: To assess the clinical significance of expression of miR-106a in colorectal cancer (CRC), and to investigate the effect of miR-106a overexpression on CRC cell invasion.

METHODS: Total RNA was extracted from 52 surgical CRC specimens and matched tumor-adjacent tissue specimens. MiR-106a expression was detected by real-time PCR, and its clinical significance was analyzed. Cell invasion assay was used to study the effect of miR-106a overexpression on CRC cell invasion.

RESULTS: The mean level of miR-106a in CRC tissues, as revealed by the 2^-△△Ct method, was 2.50 (0.017-14.269), which was significant higher than that in tumor-adjacent tissues (Z = -3.597, P < 0.01). The expression of miR-106a was correlated with TNM stag (t = 2.813, P = 0.003) and lymph node metastasis (Z = -2.635, P = 0.008). Overexpression of miR-106a induced cell invasion (P = 0.000).

CONCLUSION: Up-regulation of miR-106a may play a role in tumorigenesis and metastasis of colorectal cancer.

Epigenetics of colorectal cancer

In the early years of the molecular biology revolution, cancer research was mainly focused on genetic changes (ie, those that altered DNA sequences). Although this has been extremely useful as our understanding of the pathogenesis and biology of cancer has grown and matured, there is another realm in tumor development that does not involve changing the sequence of cellular DNA. This field is called "epigenetics" and broadly encompasses changes in the methylation of cytosines in DNA, changes in histone and chromatin structure, and alterations in the expression of microRNAs, which control the stability of many messenger RNAs and serve as "master regulators" of gene expression. This review focuses on the epigenetics of colorectal cancer and illustrates the impact epigenetics has had on this field.

MicroRNAs: relevant tools for a colorectal surgeon?

Colorectal cancer is the third most common malignancy and cause of cancer-related deaths worldwide. Approximately half of the patients diagnosed with colorectal cancer ultimately die of the condition. Death from colorectal cancer can be prevented by early detection, but unfortunately presentation is often late, with a worse prognosis. Screening by fecal occult blood testing reduces disease-specific mortality, but there is a need for sensitive and specific noninvasive biomarkers to facilitate detecting the disease, staging it, and predicting the best therapeutic options. MicroRNAs (miRNAs) are short noncoding RNA sequences that have a crucial role in the regulation of gene expression. They have significant regulatory functions in basic cellular processes, such as cell differentiation, proliferation, and apoptosis. Evidence suggests that miRNAs may function as both tumor suppressors and oncogenes. The main mechanism for changes in the function of miRNAs in cancer cells is due to aberrant gene expression. Accurate discrimination of miRNA profiles between tumor and normal mucosa in colorectal cancer allows definition of specific expression patterns of miRNAs, giving good potential as diagnostic and therapeutic targets. MiRNAs expressed in colorectal cancers are also abundantly present and stable in stool and plasma samples. Their extraction from these three sources is feasible and reproducible. The ease and reliability of determining miRNA profiles in plasma or stool makes them potential molecular markers for colorectal cancer screening. This review summarizes the role miRNAs have in colorectal cancer, highlighting particularly the potential diagnostic, prognostic, and therapeutic implications in the future treatment of the disease.

MicroRNAs as potential biomarkers in human solid tumors

MicroRNAs (miRNAs) regulate the expression of approximately 30% of protein-coding genes. Functions of miRNAs are essential to maintain a steady state of cellular machinery. Dysregulations of miRNAs play pivotal roles in the initiation and progression of malignancies. Abnormal miRNA expressions have been found in a variety of human solid tumors. Furthermore, extracellular miRNAs could circulate in body fluids, and hence show great promise for refining diagnosis and prognosis of cancer. Here we review the progress of analysis of microRNAs as a potential approach for diagnosis and prognosis of solid cancer. We will also discuss obstacles in developing miRNAs as circulating biomarkers.

The role of microRNAs in colorectal cancer

During the last decade, it has become clear that aberrant microRNA expression has a functional role in the initiation and progression of colorectal cancer (CRC). Specific microRNAs can act as either tumor suppressors or oncogenes depending on the cellular environment in which they are expressed. The expression of microRNAs is reproducibly altered in CRC, and their expression patterns are associated with diagnosis, prognosis, and therapeutic outcome in CRC. Studies have begun to examine the association of microRNA-related polymorphisms and their association with CRC incidence and prognosis as well as the possibility of using circulating microRNAs or fecal microRNA expression as noninvasive early detection biomarkers. These data suggest that microRNAs may be potential molecular classifiers, early detection biomarkers, and therapeutic targets for CRC. Here, we will review the evidence demonstrating a role of microRNAs in CRC.

MicroRNA expression signatures in solid malignancies

An ongoing challenge in cancer research is represented by the identification of new specific clinical molecular markers and pharmacological targets. During the last 10 years, microRNAs (miRNAs) have become one of the hottest subjects in the area of cancer genomics. MicroRNAs are single-stranded RNAs of 19 to 24 nucleotides in length generated through a complex maturation process. Recent studies have demonstrated that microRNAs can have an oncogene or tumor suppressor role by regulating the expression of target genes. Therefore, microRNAs are highly related to cancer processes, including initiation, growth, apoptosis, invasion, and metastasis. In this panorama, several high-through put technologies studies have revealed miRNA roles in classifying tumors and predicting patient outcome with high accuracy. We provide a review highlighting recent progress on the understanding of the cellular function of human microRNAs and their expression in solid tumors.

The role of microRNAs in colorectal cancer

During the last decade, it has become clear that aberrant microRNA expression has a functional role in the initiation and progression of colorectal cancer (CRC). Specific microRNAs can act as either tumor suppressors or oncogenes depending on the cellular environment in which they are expressed. The expression of microRNAs is reproducibly altered in CRC, and their expression patterns are associated with diagnosis, prognosis, and therapeutic outcome in CRC. Studies have begun to examine the association of microRNA-related polymorphisms and their association with CRC incidence and prognosis as well as the possibility of using circulating microRNAs or fecal microRNA expression as noninvasive early detection biomarkers. These data suggest that microRNAs may be potential molecular classifiers, early detection biomarkers, and therapeutic targets for CRC. Here, we will review the evidence demonstrating a role of microRNAs in CRC.

Circulating MACC1 transcripts in colorectal cancer patient plasma predict metastasis and prognosis

Background

Metastasis is the most frequent cause of treatment failure and death in colorectal cancer. Early detection of tumors and metastases is crucial for improving treatment strategies and patient outcome. Development of reliable biomarkers and simple tests routinely applicable in the clinic for detection, prognostication, and therapy monitoring is of special interest. We recently identified the novel gene Metastasis-Associated in Colon Cancer 1 (MACC1), a key regulator of the HGF/Met-pathway. MACC1 is a strong prognostic biomarker for colon cancer metastasis and allows identification of high-risk subjects in early stages, when determined in patients’ primary tumors. To overcome the limitation of a restricted number of molecular analyses in tumor tissue, the establishment of a non-invasive blood test for early identification of high-risk cancer patients, for monitoring disease course and therapy response is strongly needed.

Methodology/Principal Findings

For the first time, we describe a non-invasive assay for quantification of circulating MACC1 transcripts in blood of more than 300 colorectal cancer patients. MACC1 transcript levels are increased in all disease stages of the cancer patients compared to tumor-free volunteers. Highest MACC1 levels were determined in individuals with metastases (all P<0.05). Importantly, high MACC1 levels correlate with unfavorable survival (P<.0001). Combining MACC1 with circulating transcripts of the metastasis gene S100A4, a transcriptional target of the Wnt/β-catenin-pathway, improves survival prediction for newly diagnosed cancer patients.

Conclusion/Significance

This blood-based assay for circulating MACC1 transcripts, which can be quantitated on a routine basis, is clinically applicable for diagnosis, prognosis, and therapeutic monitoring of cancer patients. Here we demonstrate the diagnostic and prognostic value of circulating MACC1 transcripts in patient plasma for metastasis and survival. Since MACC1 represents a promising target for anti-metastatic therapies, circulating MACC1 transcripts may prove to be an ideal read-out for monitoring therapeutic response of future interventions targeting MACC1-induced metastasis in cancer patients.

MicroRNAs in brain metastases: big things come in small packages

Metastatic brain tumors provide a formidable obstacle in the survival of affected cancer patients, an obstacle that current treatment is essentially ineffective against. Our understanding of the metastatic cascade has demonstrated the role of incorrectly regulated protein expression and proved it to be a crucial component of this process. Recently, molecular studies have emphasized the role of microRNAs, small non-coding RNAs that alter protein expression, in the regulation of both normal and abnormal biological processes, including cancer and its metastasis to the brain. Furthermore, studies have demonstrated the ability to distinguish normal from cancerous cells, primary from secondary brain tumors, and correctly categorize metastatic brain tumor tissue of origin based solely on microRNA profiles. Interestingly, manipulation of microRNAs has proven effective in cancer treatment. With the promise of reduced toxicity, increased efficacy, and individually directed therapy, using microRNA in the treatment of metastatic brain tumors may prove very useful. In this review, we focus on the multiple potential microRNA targets for the treatment of metastatic brain lesions as well as current and future directions for its use in gene therapy.

MicroRNAs as Novel Biomarkers in Colorectal Cancer

MicroRNAs (miRNAs) play an important role in various physiologic and developmental processes and in the initiation and progression of cancer. This class of small, non-coding RNAs critically regulate gene expression at the post-transcriptional level and evidence suggests that they may function as both oncogenes and tumor suppressors. Colorectal cancer (CRC) is a major healthcare concern worldwide and in order to reduce CRC related deaths, research is aimed into the search for some novel screening approaches. In this sense, miRNAs are rapidly emerging as a novel class of biomarkers, with good potential as diagnostic and therapeutic targets. This review summarizes the recent findings of the clinicopathological relevance that miRNAs have in CRC initiation, development, and progress, highlighting their potential diagnostic, prognostic, and therapeutic use in CRC, focusing on the group of microsatellite instable and the group of hypermethylated CRCs, as well as discussing future prospects.

Cell-free Circulating miRNA Biomarkers in Cancer

Considerable attention and an enormous amount of resources have been dedicated to cancer biomarker discovery and validation. However, there are still a limited number of useful biomarkers available for clinical use. An ideal biomarker should be easily assayed with minimally invasive medical procedures but possess high sensitivity and specificity. Commonly used circulating biomarkers are proteins in serum, most of which require labor-intensive analysis hindered by low sensitivity in early tumor detection. Since the deregulation of microRNA (miRNA) is associated with cancer development and progression, profiling of circulating miRNAs has been used in a number of studies to identify novel minimally invasive miRNA biomarkers. In this review, we discuss the origin of the circulating cell-free miRNAs and their carriers in blood. We summarize the clinical use and function of potentially promising miRNA biomarkers in a variety of different cancers, along with their downstream target genes in tumor initiation and development. Additionally, we analyze some technical challenges in applying miRNA biomarkers to clinical practice.

Circulating microRNAs: new biomarkers in diagnosis, prognosis and treatment of cancer (review)

MicroRNAs (miRNAs) are small non-coding, endogenous, single-stranded RNAs. MiRNAs have been implicated in different areas such as the immune response, neural development, DNA repair, apoptosis, oxidative stress response and cancer. However, while the majority of miRNAs are found intracellularly, a significant number of miRNAs have been observed outside of cells, including various body fluids. Circulating miRNAs function as 'extracellular communication RNAs' that play an important role in cell proliferation and differentiation. MiRNA regulation is essential to many cellular processes, and escape from this regulatory network seems to be a common characteristic of several disease processes and malignant transformation. The interest in circulating miRNAs reflects in fact their central role in regulation of gene expression and the implication of miRNA-specific aberrant expression in the pathogenesis of cancer, cardiac, metabolic, neurologic, immune-related diseases as well as others. In our review we aimed to summarize the data related to the action of cellular miRNAs on the onset of various diseases, thus bringing together some of the latest information available on the role of circulating miRNAs. Additionally, the role of circulating miRNAs could be particularly relevant in the context of neoplastic diseases. At least 79 miRNAs have been reported as plasma or serum miRNA biomarkers of solid and hematologic tumors. Circulating miRNA profiling could improve the diagnosis of cancer, and could predict outcome for cancer patients, while the profiling of alterations in circulating miRNA that may signal a predisposition to cancer, could also be a therapeutic target in these patients.

Circulating microRNAs in cancer: diagnostic and prognostic significance

The involvement of microRNAs (miRs) in numerous pathological conditions is well established. In many kinds of cancer cells and animal models, various miRs have been shown to act as oncogenes or tumor suppressors. Recently, it was found that circulating miRs can be detected, and may be associated, with the clinicopathological features and prognosis of cancers, thus, providing potential novel diagnostic and prognostic markers for malignancies in humans. This review aims to address these issues based on recently published literature.

Circulating U2 small nuclear RNA fragments as a novel diagnostic biomarker for pancreatic and colorectal adenocarcinoma

Improved non-invasive strategies for early cancer detection are urgently needed to reduce morbidity and mortality. Non-coding RNAs, such as microRNAs and small nucleolar RNAs, have been proposed as biomarkers for non-invasive cancer diagnosis. Analyzing serum derived from nude mice implanted with primary human pancreatic ductal adenocarcinoma (PDAC), we identified 15 diagnostic microRNA candidates. Of those miR-1246 was selected based on its high abundance in serum of tumor carrying mice. Subsequently, we noted a cross reactivity of the established miR-1246 assays with RNA fragments derived from U2 small nuclear RNA (RNU2-1). Importantly, we found that the assay signal discriminating tumor from controls was derived from U2 small nuclear RNA (snRNA) fragments (RNU2-1f) and not from miR-1246. In addition, we observed a remarkable stability of RNU2-1f in serum and provide experimental evidence that hsa-miR-1246 is likely a pseudo microRNA. In a next step, RNU2-1f was measured by qRT-PCR and normalized to cel-54 in 191 serum/plasma samples from PDAC and colorectal carcinoma (CRC) patients. In comparison to 129 controls, we were able to classify samples as cancerous with a sensitivity and specificity of 97.7% [95% CI = (87.7, 99.9)] and 90.6% [95% CI = (80.7, 96.5)], respectively [area under the ROC curve 0.972]. Of note, patients with CRC were detected with our assay as early as UICC Stage II with a sensitivity of 81%. In conclusion, this is the first report showing that fragments of U2 snRNA are highly stable in serum and plasma and may serve as novel diagnostic biomarker for PDAC and CRC for future prospective screening studies.

Plasma miR-601 and miR-760 are novel biomarkers for the early detection of colorectal cancer

Background

Colorectal cancer (CRC) is a major cause of death worldwide. Sensitive, non-invasive diagnostic screen methods are urgently needed to improve its survival rates. Stable circulating microRNA offers unique opportunities for the early diagnosis of several diseases, including cancers. Our aim has been to find new plasma miRNAs that can be used as biomarkers for the detection of CRC.

Methodology/Principal Findings

According to the results of miRNA profiling performed on pooling plasma samples form 10 CRC patients or 10 healthy controls, a panel of miRNAs (hsa-miR-10a, -19a, -22*, -24, -92a, 125a-5p, -141, -150, -188-3p, -192, -210, -221, -224*, -376a, -425*, -495, -572, -601, -720, -760 and hsa-let-7a, -7e) were deregulated in CRC plasma with fold changes >5. After large scale validation by qRT-PCR performed on another 191 independent individuals (90 CRC, 43 advanced adenoma and 58 healthy participants), we found that the levels of plasma miR-601 and miR-760 were significantly decreased in colorectal neoplasia (carcinomas and advanced adenomas) compared with healthy controls. ROC curve analysis showed that plasma miR-601 and miR-760 were of significant diagnostic value for advanced neoplasia. These two miRNAs together yield an AUC of 0.792 with 83.3% sensitivity and 69.1% specificity for separating CRC from normal controls, and yield an AUC of 0.683 with 72.1% sensitivity and 62.1% specificity in discriminating advanced adenomas from normal controls.

Conclusions/Significance

Plasma miR-601 and miR-760 can potentially serve as promising non-invasive biomarkers for the early detection of CRC.