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

Cell-free nucleic acids as noninvasive biomarkers for colorectal cancer detection

Cell-free nucleic acids (CFNA) have been reported by several authors in blood, stool, and urine of patients with colorectal cancer (CRC). These genetic biomarkers can be an indication of neoplastic colorectal epithelial cells, and can thus potentially be used as noninvasive tests for the detection of the disease in CRC patients and monitor their staging, without the need to use heavier and invasive tools. In a number of test-trials, these genetic tests have shown the advantage of non-invasiveness, making them well accepted by most of the patients, without major side effects. They have also shown a promising sensitivity and specificity in the detection of malignant and premalignant neoplasms. Moreover, costs for performing such tests are very low. Several studies reported and confirmed the proof of the principle for these genetic tests for screening, diagnosis, and prognosis; the main challenge of translating this approach from research to clinical laboratory is the validation from large and long-term randomized trials to prove sustainable high sensitivity and specificity. In this paper, we present a review on the noninvasive genetics biomarkers for CRC detection described in the literature and the challenges that can be encountered for validation processes.

DNA methylation and microRNA biomarkers for noninvasive detection of gastric and colorectal cancer

Cancer initiation and progression is controlled by both genetic and epigenetic events. Epigenetics refers to the study of mechanisms that alter gene expression without permanently altering the DNA sequence. Epigenetic alterations are reversible and heritable, and include changes in histone modifications, DNA methylation, and non-coding RNA-mediated gene silencing. Disruption of epigenetic processes can lead to altered gene function and malignant cellular transformation. Aberrant epigenetic modifications occur at the earliest stages of neoplastic transformation and are now believed to be essential players in cancer initiation and progression. Recent advances in epigenetics have not only offered a deeper understanding of the underlying mechanism(s) of carcinogenesis, but have also allowed identification of clinically relevant putative biomarkers for the early detection, disease monitoring, prognosis and risk assessment of cancer patients. At this moment, DNA methylation and non-coding RNA including with microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) represent the largest body of available literature on epigenetic biomarkers with the highest potential for cancer diagnosis. Following identification of cell-free nucleic acids in systematic circulation, increasing evidence has demonstrated the potential of cell-free epigenetic biomarkers in the blood or other body fluids for cancer detection. In this article, we summarize the current state of knowledge on epigenetic biomarkers - primarily DNA methylation and non-coding RNAs - as potential substrates for cancer detection in gastric and colorectal cancer, the two most frequent cancers within the gastrointestinal tract. We also discuss the obstacles that have limited the routine use of epigenetic biomarkers in the clinical settings and provide our perspective on approaches that might help overcome these hurdles, so that these biomarkers can be readily developed for clinical management of cancer patients.

Polymorphism in miRNA-1 target site and circulating miRNA-1 phenotype are associated with the decreased risk and prognosis of coronary artery disease

MiRNA molecules have been identified to play key roles in a broad range of physiologic and pathologic processes. Polymorphisms in microRNA target sites (PolymiRTSs) can disturb or obstruct miRNA binding and consequentially influence regulation of the target genes. A two-step study design was used in this study. A case-control study was designed to assess the relationship between miRNA-1 target site rs9548934C→T polymorphism in target gene (Component of Oligomeric Golgi Complex 6, COG6) and risk of coronary artery disease (CAD) in 1013 patients and 610 normal controls. This genetic variant was also evaluated for the association with major adverse cardiovascular events (MACE) of CAD in a follow-up study, including 785 (785/1013) patients followed up for 42 months. The phenotypes of circulating miRNA-1 levels in 34 cases were slightly lower than that of 40 controls but not significantly different (P = 0.090). The CT and CT/TT genotypes were associated with a 34% and 26% decreased risk of CAD, and the TT and CT/TT genotypes were associated with a 76% and 49% decreased risk of MACE of CAD. Cox regression analysis showed that rs9548937 C/T variant was associated with a decreased risk of MACE, while age, diabetes mellitus, higher levels of CRP (≥ 3.80 mg/L) and three pathological changes in the coronary artery were associated with an increased risk of MACE. Our findings implicate miRNA-1 target site rs9548934C→T genotypes, circulating miRNA-1 phenotype and CRP levels may modulate the occurrence and MACE of CAD.

Biomarkers for early detection of colorectal cancer and polyps: systematic review

There is growing interest in early detection of colorectal cancer as current screening modalities lack compliance and specificity. This study systematically reviewed the literature to identify biomarkers for early detection of colorectal cancer and polyps. Literature searches were conducted for relevant papers since 2007. Human studies reporting on early detection of colorectal cancer and polyps using biomarkers were included. Methodologic quality was evaluated, and sensitivity, specificity, and the positive predictive value (PPV) were reported. The search strategy identified 3,348 abstracts. A total of 44 papers, examining 67 different tumor markers, were included. Overall sensitivities for colorectal cancer detection by fecal DNA markers ranged from 53% to 87%. Combining fecal DNA markers increased the sensitivity of colorectal cancer and adenoma detection. Canine scent detection had a sensitivity of detecting colorectal cancer of 99% and specificity of 97%. The PPV of immunochemical fecal occult blood test (iFOBT) is 1.26%, compared with 0.31% for the current screening method of guaiac fecal occult blood test (gFOBT). A panel of serum protein biomarkers provides a sensitivity and specificity above 85% for all stages of colorectal cancer, and a PPV of 0.72%. Combinations of fecal and serum biomarkers produce higher sensitivities, specificities, and PPVs for early detection of colorectal cancer and adenomas. Further research is required to validate these biomarkers in a well-structured population-based study.

The validity of circulating microRNAs in oncology: five years of challenges and contradictions

MicroRNAs (miRNAs) in circulation have received an increasing amount of interest as potential minimal invasive diagnostic tools in oncology. Several diagnostic, prognostic and predictive signatures have been proposed for a variety of cancers at different stages of disease, but these have not been subjected to a critical review regarding their validity: reproducible identification in comparable studies and/or with different platforms of miRNA detection. In this review, we will critically address the results of circulating miRNA research in oncology that have been published between January 2008 and June 2013 (5.5 years), and discuss pre-analytical challenges, technological pitfalls and limitations that may contribute to the non-reproducibility of circulating miRNA research.

Limited diagnostic value of microRNAs for detecting colorectal cancer: a meta-analysis

BACKGROUND

MicroRNAs have been demonstrated to play important roles in the development and progression of colorectal cancer. Several studies utilizing microRNAs as diagnostic biomarkers for colorectal cancer (CRC) have been reported. The aim of this meta-analysis was to comprehensively and quantitatively summarize the diagnostic value of microRNAs for detecting colorectal cancer.

METHODS

We searched PubMed, Embase and Cochrane Library for published studies that used microRNAs as biomarkers for the diagnosis of colorectal cancer. Summary estimates for sensitivity, specificity and other measures of accuracy of microRNAs in the diagnosis of colorectal cancer were calculated using the bivariate random effects model. A summary receiver operating characteristic (SROC) curve was also generated to summarize the overall effectiveness of the test.

RESULT

Thirteen studies from twelve published articles met the inclusion criteria and were included. The overall sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odd ratio of microRNAs for the diagnosis of colorectal cancer were 0.81 (95%CI: 0.79-0.84), 0.78 (95%CI: 0.75-0.82), 4.14 (95%CI: 2.90- 5.92), 0.24 (95%CI: 0.19-0.30), and 19.2 (95%CI: 11.7-31.5), respectively. The area under the SROC curve was 0.89.

CONCLUSIONS

The current evidence suggests that the microRNAs test might not be used alone as a screening tool for CRC. Combining microRNAs testing with other conventional tests such as FOBT may improve the diagnostic accuracy for detecting CRC.

Advances in epigenetic biomarker research in colorectal cancer

Colorectal cancer (CRC) causes approximately 600000 deaths annually and is the third leading cause of cancer mortality worldwide. Despite significant advancements in treatment options, CRC patient survival is still poor owing to a lack of effective tools for early diagnosis and a limited capacity for optimal therapeutic decision making. Since there exists a need to find new biomarkers to improve diagnosis of CRC, the research on epigenetic biomarkers for molecular diagnostics encourages the translation of this field from the bench to clinical practice. Epigenetic alterations are thought to hold great promise as tumor biomarkers. In this review, we will primarily focus on recent advances in the study of epigenetic biomarkers for colorectal cancer and discuss epigenetic biomarkers, including DNA methylation, microRNA expression and histone modification, in cancer tissue, stool, plasma, serum, cell lines and xenografts. These studies have improved the chances that epigenetic biomarkers will find a place in the clinical practices of screening, early diagnosis, prognosis, therapy choice and recurrence surveillance for CRC patients. However, these studies have typically been small in size, and evaluation at a larger scale of well-controlled randomized clinical trials is the next step that is necessary to increase the quality of epigenetic biomarkers and ensure their widespread clinical use.

MicroRNAs in colorectal cancer as markers and targets: Recent advances

MicroRNAs are evolutionarily conserved small non-coding RNA molecules encoded by eukaryotic genomic DNA, and function in post-transcriptional regulation of gene expression via base-pairing with complementary sequences in target mRNAs, resulting in translational repression or degradation of target mRNAs. They represent one of the major types of epigenetic modification and play important roles in all aspects of cellular activities. Altered expression of microRNAs has been found in various human diseases including cancer. Many efforts have been made to discover the characteristic microRNA expression profiles, to understand the roles of aberrantly expressed microRNAs and underlying mechanisms in different cancers. With the application of DNA microarray, real-time quantitative polymerase chain reaction and other molecular biology techniques, increasing evidence has been accumulated which reveal that aberrant microRNAs can be detected not only intracellularly within the cancer cells, but also extracellularly in plasma of patients, postulating the potential of aberrant microRNAs as promising diagnostic/prognostic markers and attracting therapeutic targets. This review is intended to provide the most recent advances in microRNA studies in one of the most common cancers, colorectal cancer, especially the identification of those specifically altered microRNAs in colorectal cancer, validation for their relevance to clinical pathological parameters of patients, functional analyses and potential applications of these microRNAs.

Identification of miRNAs differentially expressed in clinical stages of human colorectal carcinoma-an investigation in Guangzhou, China

Aberrant expression of microRNAs (miRNAs) has been implicated in human cancer, including colorectal cancer (CRC). Such dysregulated miRNAs may have potential as diagnostic markers or therapeutic targets. However, the nature of an association between these miRNAs and clinical stages of CRC is still not clear. To this end, we performed a miRNA profiling of 1547 distinct human miRNAs using 31 samples of tumor and paired normal mucosa obtained from 31 CRC patients. Based on statistical analyses of profiling data, we identified 569 miRNAs that were significantly dysregulated in CRC relative to normal tissues (P<0.05). Among the 569 dysregulated miRNAs, downregulation of 17 was associated with stages II, III, and IV colon and rectal cancers (separate or combined), according to our criteria. We also assessed the potential of these dysregulated miRNAs as diagnostic biomarkers for CRC patients who were without metastasis, and the value of the dysregulated miRNAs for predicting metastasis, lymph node and distant. Their distinct expression patterns in colon and rectal cancers were also examined. Although our findings cannot be immediately applied toward clinical diagnosis, our new study model for determining and assessing the biomarker potential of dysregulated miRNAs should be useful in further research in detection of human CRC.

Use of blood-based biomarkers for early diagnosis and surveillance of colorectal cancer

Early screening for colorectal cancer (CRC) holds the key to combat and control the increasing global burden of CRC morbidity and mortality. However, the current available screening modalities are severely inadequate because of their high cost and cumbersome preparatory procedures that ultimately lead to a low participation rate. People simply do not like to have colonoscopies. It would be ideal, therefore, to develop an alternative modality based on blood biomarkers as the first line screening test. This will allow for the differentiation of the general population from high risk individuals. Colonoscopy would then become the secondary test, to further screen the high risk segment of the population. This will encourage participation and therefore help to reach the goal of early detection and thereby reduce the anticipated increasing global CRC incidence rate. A blood-based screening test is an appealing alternative as it is non-invasive and poses minimal risk to patients. It is easy to perform, can be repeated at shorter intervals, and therefore would likely lead to a much higher participation rate. This review surveys various blood-based test strategies currently under investigation, discusses the potency of what is available, and assesses how new technology may contribute to future test design.

Identification of a circulating microRNA signature for colorectal cancer detection

Prognosis of patients with colorectal cancer (CRC) is generally poor because of the lack of simple, convenient, and noninvasive tools for CRC detection at the early stage. The discovery of microRNAs (miRNAs) and their different expression profiles among different kinds of diseases has opened a new avenue for tumor diagnosis. We built a serum microRNA expression profile signature and tested its specificity and sensitivity as a biomarker in the diagnosis of CRC. We also studied its possible role in monitoring the progression of CRC. We conducted a two phase case-control test to identify serum miRNAs as biomarkers for CRC diagnosis. Using quantitative reverse transcription polymerase chain reactions, we tested ten candidate miRNAs in a training set (30 CRCs vs 30 controls). Risk score analysis was used to evaluate the diagnostic value of the serum miRNA profiling system. Other independent samples, including 83 CRCs and 59 controls, were used to validate the diagnostic model. In the training set, six serum miRNAs (miR-21, let-7g, miR-31, miR-92a, miR-181b, and miR-203) had significantly different expression levels between the CRCs and healthy controls. Risk score analysis demonstrated that the six-miRNA-based biomarker signature had high sensitivity and specificity for distinguishing the CRC samples from cancer-free controls. The areas under the receiver operating characteristic (ROC) curve of the six-miRNA signature profiles were 0.900 and 0.923 for the two sets of serum samples, respectively. However, for the same serum samples, the areas under the ROC curve used by the tumor markers carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were only 0.649 and 0.598, respectively. The expression levels of the six serum miRNAs were also correlated with CRC progression. Thus, the identified six-miRNA signature can be used as a noninvasive biomarker for the diagnosis of CRC, with relatively high sensitivity and specificity.

miR-146a G>C polymorphisms and risk of hepatocellular carcinoma in a Chinese population

MicroRNAs (miRNAs) are thought to have a role in cancer development. We investigated the association among miR-146a G>C genetic variations, hepatitis B (HBV), and C (HCV) infection, and risk of hepatocellular carcinoma (HCC). Unconditional logistical regression analysis suggested that the miR-146a GG genotype and G allele carried a 2.10- (95 % confidence interval (CI)=1.03-4.37) and 1.42-fold (95 % CI=1.07-1.92) increased HCC risk, respectively. HBV-positive subjects carrying the miR-146a GG genotype (odds ratio (OR)=2.95, 95 % CI=1.31-6.81) and G allele (OR=1.65, 95 % CI=1.15-2.58) had an increased risk of HCC. However, the miR-146a GG genotype and G allele did not carry a significantly enhanced risk of HCC in either hepatitis-negative or HCV-infected subjects. miR-146a G>C polymorphisms appear to influence susceptibility to HCC, especially in HBV-infected patients.

Proteomics, genomics and transcriptomics: their emerging roles in the discovery and validation of colorectal cancer biomarkers

Colorectal cancer (CRC) is the second most common cancer in females and the third in males. Since CRC is often diagnosed at an advanced stage when prognosis is poor, identification of biomarkers for early diagnosis is urgently required. Recent advances in proteomics, genomics and transcriptomics have facilitated high-throughput profiling of data generated from CRC-related genes and proteins, providing a window of information for biomarker discovery and validation. However, transfer of candidate biomarkers from bench to bedside remains a dilemma. In this review, we will discuss emerging proteomic technologies and highlight various sample types utilized for proteomics-based identification of CRC biomarkers. Moreover, recent breakthroughs in genomics and transcriptomics for the identification of CRC biomarkers, with particular emphasis on the merits of emerging methylomic and miRNAomic strategies, will be discussed. Integration of proteomics, genomics and transcriptomics will facilitate the discovery and validation of CRC biomarkers leading to the emergence of personalized medicine.

Down-regulation of ncRAN, a long non-coding RNA, contributes to colorectal cancer cell migration and invasion and predicts poor overall survival for colorectal cancer patients

Accumulating evidence has indicated that long non-coding RNAs (lncRNAs) play critical roles in regulating cellular processes, such as cell growth and apoptosis, as well as cancer progression and metastasis. ncRAN (non-coding RNA expressed in aggressive neuroblastoma) was previously shown to be dramatically up-regulated and associated with poor prognosis in human neuroblastoma. This lncRNA also plays an important role in bladder cancer growth and invasion. Colorectal cancer (CRC) progression typically follows a complex cascade from primary malignancy to distant metastasis, but whether the aberrant expression of ncRAN in CRC is associated with malignancy, metastasis or prognosis remains unknown. In this study, we demonstrated that ncRAN expression is significantly down-regulated in tumor tissue and CRC cell lines compared with adjacent normal tissue and a normal intestinal mucous cell line. Reduced expression of ncRAN was detected in poorly differentiated or undifferentiated tumors and in tumors with liver metastases. Kaplan-Meier analysis indicated that patients with lower ncRAN expression have a worse overall survival. Moreover, multivariate analysis revealed that decreased expression of ncRAN is an independent predictor of overall survival. Our experimental data indicated that ncRAN mediates the in vitro migration and invasion of CRC cells. Together, these results suggest that ncRAN might represent a novel prognostic indicator, a biomarker for the early detection of metastasis and a target for gene therapy in CRC.

Tumor-associated circulating microRNAs as biomarkers of cancer

MicroRNAs (miRNAs), the 17- to 25-nucleotide long noncoding RNAs that modulate the expression of mRNAs and proteins, have emerged as critical players in cancer initiation and progression processes. Deregulation of tissue miRNA expression levels associated with specific genetic alterations has been demonstrated in cancer, where miRNAs function either as oncogenes or as tumor-suppressor genes and are shed from cancer cells into circulation. The present review summarizes and evaluates recent advances in our understanding of the characteristics of tumor tissue miRNAs, circulating miRNAs, and the stability of miRNAs in tissues and their varying expression profiles in circulating tumor cells, and body fluids including blood plasma. These advances in knowledge have led to intense efforts towards discovery and validation of differentially expressing tumor-associated miRNAs as biomarkers and therapeutic targets of cancer. The development of tumor-specific miRNA signatures as cancer biomarkers detectable in malignant cells and body fluids should help with early detection and more effective therapeutic intervention for individual patients.

Circulating microRNAs as Promising Tumor Biomarkers

microRNAs (miRNAs) are small, nonprotein-coding RNAs that function as posttranscriptional regulators of target genes. miRNAs are involved in multiple cell differentiation, proliferation, and apoptosis processes that are closely related to tumorigenesis. Circulating miRNAs are promising cancer biomarkers under development with great translational potential in personalized medicine. Here, we describe the origin and function of circulating miRNAs and compare the current new high-throughput technology applied to miRNA quantitation. The latest publications on circulating miRNAs were summarized, indicating that miRNAs are potential biomarkers of diagnosis, prognosis, and treatment response of major cancer types including prostate, breast, lung, colorectal, and hematological cancers. We addressed the strengths and limitations of applying circulating miRNAs in clinical laboratory and several issues associated with the accurate measurement of circulating miRNAs.

microRNA-202-3p inhibits cell proliferation by targeting ADP-ribosylation factor-like 5A in human colorectal carcinoma

PURPOSE

MicroRNAs (miRNA) that are strongly implicated in carcinogenesis have recently reshaped our understanding of the role of non-protein-coding RNAs. Here, we focused on the function and molecular mechanism of miR-202-3p and its potential clinical application in colorectal cancer.

EXPERIMENTAL DESIGN

miR-202-3p expression was determined by quantitative reverse transcriptase PCR (qRT-PCR) in 94 colorectal cancer tissues and corresponding noncancerous tissues (NCT). Cell proliferation and colony formation assays in vitro and xenograft experiments in vivo were used to evaluate the effect of miR-202-3p on colorectal cancer cell proliferation. Luciferase assay and Western blot analysis were performed to validate the potential targets of miR-202-3p after the preliminary screening by online prediction and microarray analysis. The mRNA and protein levels of target genes were detected by qRT-PCR and immunohistochemical staining. The copy number of pre-miR-202 was measured by quantitative PCR.

RESULTS

First, miR-202-3p was significantly downregulated in 46.7% colorectal cancer samples compared with NCTs. The overexpression of miR-202-3p inhibited colorectal cancer cell growth in vitro and repressed tumorigenesis in nude mice. Then, miR-202-3p downregulated ADP-ribosylation factor-like 5A (ARL5A) protein level by binding to its 3' untranslated region, and knockdown of ARL5A phenocopied the proliferation inhibition effect of miR-202-3p. Furthermore, both of ARL5A mRNA and protein levels were upregulated in colorectal cancer samples compared with NCTs and high ARL5A protein levels predicted a poor prognosis.

CONCLUSIONS

miR-202-3p might function as a tumor suppressor in colorectal cancer, and ARL5A, the functional target of miR-202-3p in colorectal cancer, is a potential prognostic factor for colorectal cancer.

A plasma microRNA panel for detection of colorectal adenomas: a step toward more precise screening for colorectal cancer

OBJECTIVE

The main objective of this study was to investigate the potential use of circulating microRNAs (miRNAs) as biomarkers of colorectal (CR) adenomas.

BACKGROUND

Detection of precancerous lesions such as CR adenoma is a key to reduce CR cancer (CRC) mortality. There is a great need for accurate, noninvasive biomarkers for detection of CR adenoma and CRC. MiRNAs are non-protein-coding RNAs that regulate gene expression. Our prior work investigated the dysregulation of 5 plasma miRNAs in CRC patients. As intended, we undertook a more comprehensive plasma-miRNA screening study in patients with CR adenoma and CRC.

METHODS

We screened for 380 plasma-miRNAs using microfluidic array technology (Applied BioSystems) in a screening cohort of 12 healthy controls, 9 patients with CR adenomas, and 20 patients with CRC. A panel of the most dysregulated miRNAs (P < 0.05, False Discovery Rate: 5%) was then validated in a blinded cohort of 26 healthy controls, 16 patients with large adenomas, and 45 patients with CRC.

RESULTS

A panel of 8 plasma miRNAs (miR-532-3p, miR-331, miR-195, miR-17, miR-142-3p, miR-15b, miR-532, and miR-652) distinguished polyps from controls with high accuracy [area under curve (AUC) = 0.868 (95% confidence interval [CI]: 0.76-0.98)]. In addition, a panel of 3 plasma miRNAs (miR-431, miR-15b, and miR-139-3p) distinguished Stage IV CRC from controls with an [AUC = 0.896 (95% CI: 0.78-1.0)]. Receiver-operating-characteristic curves of miRNA panels for all CRC versus controls and polyps versus all CRC showed AUC values of 0.829 (95% CI: 0.73-0.93) and 0.856 (95% CI: 0.75-0.97), respectively.

CONCLUSIONS

Plasma miRNAs are reliable, noninvasive, and inexpensive markers for CR adenomas. This miRNA panel warrants study in larger cohorts. Plasma-based assays could provide better screening compliance compared to fecal occult blood or endoscopic screening.

The relationship between and clinical significance of MicroRNA-32 and phosphatase and tensin homologue expression in colorectal cancer

MicroRNAs (miRNAs, miRs) are suspected to play important roles in carcinogenesis. MiR-32 has altered expression in colorectal cancer (CRC); however, the clinical significance of miR-32 expression in the process of carcinogenesis is poorly understood. In this study, we determined the levels of, the correlation between, and the clinical significance of the expression of miR-32 and phosphatase and tensin homologue (PTEN), a tumor suppressor targeted by miR-32, in CRC. The levels of miR-32 and PTEN gene expression in 35 colorectal carcinoma samples, 35 corresponding cancer-adjacent tissue samples, 27 colorectal adenoma samples, and 16 normal tissue samples were quantified using real-time quantitative reverse transcriptase-polymerase chain reaction. PTEN protein expression was determined using western blot and immunohistochemistry (IHC). The relationship between the miR-32 and PTEN protein expression and clinicopathological factors was analyzed. Significant upregulation of miR-32 expression and reduction of PTEN were identified in CRC tissues. High miR-32 levels were significantly associated with lymph node and distant metastasis, and Kaplan-Meier analysis indicated that patients with high miR-32 expression had a poor overall survival. Low PTEN protein expression was also significantly correlated with distant metastasis. An inverse relationship between miR-32 and PTEN protein expression was identified. In addition, IHC analysis revealed weak or indiscernible PTEN staining in tumor tissue. MiR-32 overexpression was correlated with specific CRC clinicopathological features and may be a marker of poor prognosis in CRC patients. MiR-32 and PTEN expression were inversely correlated, and miR-32 may be associated with the development of CRC.

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.

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.

Centrifugation: an important pre-analytic procedure that influences plasma microRNA quantification during blood processing

Circulating microRNAs are robustly present in plasma or serum and have become a research focus as biomarkers for tumor diagnosis and prognosis. Centrifugation is a necessary procedure for obtaining high-quality blood supernatant. Herein, we investigated one-step and two-step centrifugations, two centrifugal methods routinely used in microRNA study, to explore their effects on plasma microRNA quantification. The microRNAs obtained from one-step and two-step centrifugations were quantified by microarray and TaqMan-based real-time quantitative polymerase chain reaction (Q-PCR). Dynamic light scattering was performed to explore the difference underlying the two centrifugal methods. The results from the microarray containing 1,347 microRNAs showed that the signal detection rate was greatly decreased in the plasma sample prepared by two-step centrifugation. More importantly, the microRNAs missing in this plasma sample could be recovered and detected in the precipitate generated from the second centrifugation. Consistent with the results from microarray, a marked decrease of three representative microRNAs in two-step centrifugal plasma was validated by Q-PCR. According to the size distribution of all nanoparticles in plasma, there were fewer nanoparticles with size >1,000 nm in two-step centrifugal plasma. Our experiments directly demonstrated that different centrifugation methods produced distinct quantities of plasma microRNAs. Thus, exosomes or protein complexes containing microRNAs may be involved in large nanoparticle formation and may be precipitated after two-step centrifugation. Our results remind us that sample processing methods should be first considered in conducting research.

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.

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.

Personalized medicine in screening for malignant disease: a review of methods and applications

Personalized medicine (PM) is currently a hot topic in the professional world. It is often called the medicine of the future and has already achieved resounding success in the area of targeted therapy. Nevertheless, integration of the concepts of PM into routine clinical practice is slow. This review is intended to give an overview of current and potential applications of PM in oncology. PM could soon play a decisive role, especially in screening. The relevance of PM in screening was examined in the case of four common cancers (colorectal cancer, lung cancer, breast cancer, and prostate cancer). A literature search was performed. This showed that biomarkers in particular play a crucial role in screening. In summary, it can be emphasized that there are already numerous known promising biomarkers in malignant disease. This results in several possibilities for individualizing and revolutionizing screening.

Identification and Insilico Analysis of Retinoblastoma Serum microRNA Profile and Gene Targets Towards Prediction of Novel Serum Biomarkers

Retinoblastoma (RB) is a malignant tumor of the retina seen in children, and potential non invasive biomarkers are in need for rapid diagnosis and for prognosticating the therapy. This study was undertaken to identify the differentially expressed miRNAs in the serum of children with RB in comparison with the normal age matched serum, to analyze its concurrence with the existing RB tumor miRNA profile, to identify its novel gene targets specific to RB, and to study the expression of a few of the identified oncogenic miRNAs in the advanced stage primary RB patient’s serum sample. MiRNA profiling was performed on 14 pooled serum from children with advanced RB and 14 normal age matched serum samples, wherein 21 miRNAs were found to be upregulated (fold change ≤ −2.0, P ≤ 0.05) and 24 to be downregulated (fold change ≥ +2.0, P ≤ 0.05). Furthermore, intersection of 59 significantly deregulated miRNAs identified from RB tumor profiles with that of miRNAs detected in serum profile revealed that 33 miRNAs had followed a similar deregulation pattern in RB serum. Later we validated a few of the miRNAs (miRNA 17-92) identified by microarray in the RB patient serum samples (n = 20) by using qRT-PCR. Expression of the oncogenic miRNAs, miR-17, miR-18a, and miR-20a by qRT-PCR was significant in the serum samples exploring the potential of serum miRNAs identification as noninvasive diagnosis. Moreover, from miRNA gene target prediction, key regulatory genes of cell proliferation, apoptosis, and positive and negative regulatory networks involved in RB progression were identified in the gene expression profile of RB tumors. Therefore, these identified miRNAs and their corresponding target genes could give insights on potential biomarkers and key events involved in the RB pathway.

The curious case of miRNAs in circulation: potential diagnostic biomarkers?

The pervasive occurrence of cell-free miRNAs in circulation suggests that these species play an emerging role as regulatory molecules in the secretory environment. Are these molecules released fortuitously with no clear biological intent? Or do they constitute a regulatory architecture that has evolved to modulate gene expression using the highways and byways of the circulatory system? The study of circulating miRNAs continues to increase our understanding of the regulation of genomes. The diversity of acellular miRNAs from a functional perspective is discussed, and in particular we explore their utility in a clinical setting as blood-based biomarkers for diseases.