Identification of serum microRNAs as novel non-invasive biomarkers for early detection of gastric cancer

microRNA-221 and microRNA-18a identification in stool as potential biomarkers for the non-invasive diagnosis of colorectal carcinoma

BACKGROUND

The detection of microRNA (miRNA) dysregulation in stool is a novel approach for the diagnosis of colorectal carcinoma (CRC). The aim of this study is to investigate the use of miR-221 and miR-18a in stool samples as non-invasive biomarkers for CRC diagnosis.

METHODS

A miRNA expression array containing 667 miRNAs was performed to identify miRNA dysregulation in CRC tissues. We focused on miR-221 and miR-18a, two significantly upregulated miRNAs which were subsequently verified in 40 pairs of CRC tissues and 595 stool samples (198 CRCs, 199 polyps and 198 normal controls).

RESULTS

miR-221 and miR-18a were upregulated in the miRNA expression array. miR-221 and miR-18a levels were also significantly higher in 40 CRC tumours compared with their respective adjacent normal tissues. In stool samples, miR-221 and miR-18a showed a significant increasing trend from normal controls to late stages of CRC (P<0.0001). The levels of stool miR-221 and miR-18a were both significantly higher in subjects with stages I+II (miR-221: P<0.0001, miR-18a: P<0.0001) and stages III+IV of CRC (miR-221: P=0.0004, miR-18a: P<0.0001) compared with normal controls. The AUC of stool miR-221 and miR-18a were 0.73 and 0.67 for CRC patients as compared with normal controls, respectively. No significant differences in stool miR-221 and miR-18a levels were found between patients with proximal and distal CRCs. The use of antibiotics did not influence stool miRNA-221 and miRNA-18a levels.

CONCLUSIONS

Stool-based miR-221 can be used as a non-invasive biomarker for the detection of CRC.

MicroRNAs as potential biomarkers for gastric cancer

Gastric cancer is the fourth most common cancer in the world and the second leading cause of cancer-related death. More than 80% of diagnoses occur at the middle to late stage of the disease, highlighting an urgent need for novel biomarkers detectable at earlier stages. Recently, aberrantly expressed microRNAs (miRNAs) have received a great deal of attention as potential sensitive and accurate biomarkers for cancer diagnosis and prognosis. This review summarizes the current knowledge about potential miRNA biomarkers for gastric cancer that have been reported in the publicly available literature between 2008 and 2013. Available evidence indicates that aberrantly expressed miRNAs in gastric cancer correlate with tumorigenesis, tumor proliferation, distant metastasis and invasion. Furthermore, tissue and cancer types can be classified using miRNA expression profiles and next-generation sequencing. As miRNAs in plasma/serum are well protected from RNases, they remain stable under harsh conditions. Thus, potential functions of these circulating miRNAs can be deduced and may implicate their diagnostic value in cancer detection. Circulating miRNAs, as well as tissue miRNAs, may allow for the detection of gastric cancer at an early stage, prediction of prognosis, and monitoring of recurrence and/or lymph node metastasis. Taken together, the data suggest that the participation of miRNAs in biomarker development will enhance the sensitivity and specificity of diagnostic and prognostic tests for gastric cancer.

Perspectives on new biomarkers in gastric cancer: Diagnostic and prognostic applications

Gastric cancer is considered one of the most deadly tumors worldwide. Even with the decline in its incidence, the mortality rate of this disease has remained high, mainly due to its late diagnosis and to the lack of precise prognostic markers. The main purpose of this review is to present genetic, epigenetic and proteomic molecular markers that may be used in a diagnostic and prognostic manner and to discuss the pros and cons of each type of marker for improving clinical practice. In this sense, we observed that the use of genetic markers, especially mutations and polymorphisms, should be carefully considered, as they are strongly affected by ethnicity. Proteomic-based markers show promise, but the higher costs of the associated techniques continue to make this approach expensive for routine use. Alternatively, epigenetic markers appear to be very promising, as they can be detected in bodily fluids as well as tissues. However, such markers must be used carefully because epigenetic changes may occur due to environmental factors and aging. Despite the advances in technology and its access, to date, there are few defined biomarkers of prognostic and diagnostic use for gastric tumors. Therefore, the use of a panel of several approaches (genetic, epigenetic and proteomic) should be considered the best alternative for clinical practice.

MicroRNA-410 suppresses migration and invasion by targeting MDM2 in gastric cancer

Gastric cancer is one of the most frequent malignancies in tumors in the East Asian countries. Identifying precise prognostic markers and effective therapeutic targets is important in the treatment of gastric cancer. microRNAs (miRNAs) play important roles in tumorigenesis. However, the mechanisms by which miRNAs regulate gastric cancer metastasis remain poorly understood. In this study, we found that the levels of miR-410 in gastric cancer and cell lines were much lower than that in the normal control, respectively, and the lower level of miR-410 was significantly associated with lymph-node metastasis. Transfection of miR-410 mimics could significantly inhibit the cell proliferation, migration and invasion in the HGC-27 gastric cancer cell lines. In contrast, knockdown of miR-410 had the opposite effect on the cell proliferation, migration and invasion. Moreover, we also found that MDM2 was negatively regulated by miR-410 at the post-transcriptional level, via a specific target site with the 3′UTR by luciferase reporter assay. The expression of MDM2 was inversely correlated with miR-410 expression in gastric cancer tissues, and overexpression of MDM2 in miR-410-transfected gastric cancer cells effectively rescued the inhibition of cell proliferation and invasion caused by miR-410. Thus, our findings suggested that miR-410 acted as a new tumor suppressor by targeting the MDM2 gene and inhibiting gastric cancer cells proliferation, migration and invasion. The findings of this study contributed to the current understanding of these functions of miR-410 in gastric cancer.

Identification of 9 serum microRNAs as potential noninvasive biomarkers of human astrocytoma

BACKGROUND

Circulating microRNAs (miRNAs) are emerging as promising biomarkers for human cancer. In the current study, we investigated the potential use of serum miRNAs as biomarkers for diagnosis and prognosis in a cohort of Chinese astrocytoma patients.

METHODS

An initial screening of the circulating miRNA expression profile was performed on pooled serum samples from 10 preoperative patients and 10 healthy controls using a TaqMan low-density array. The selected serum miRNAs were then validated in 90 preoperative patients and 110 healthy controls who were randomly divided into a training set and a validation set. An additional double-blind test was performed in 50 astrocytomas and 50 controls to assess the serum miRNA-based biomarker accuracy in predicting astrocytoma. The differentially expressed miRNAs were evaluated in paired preoperative and postoperative serum samples from 73 astrocytoma patients. The correlation of the miRNA levels with survival in astrocytoma samples was estimated.

RESULTS

Nine serum miRNAs were significantly increased in the astrocytoma patients. The biomarker composed of these 9 miRNAs had high sensitivity, specificity, and accuracy. These 9 miRNAs were markedly decreased in the serum after operation. The upregulation of miR-20a-5p, miR-106a-5p, and miR-181b-5p was associated with advanced clinical stages of astrocytoma. Kaplan-Meier survival analysis showed that the high expression of miR-19a-3p, miR-106a-5p, and miR-181b-5p was significantly associated with poor patient survival. Finally, the combined 3-miRNAs panel was an important prognostic predictor, independent of other clinicopathological factors.

CONCLUSIONS

The results indicated the potential of serum miRNAs as novel diagnostic and prognostic biomarkers for human astrocytoma.

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.

Transforming growth factor β1 increases p27 levels via synthesis and degradation mechanisms in the hyperproliferative gastric epithelium in rats

Throughout postnatal development, the gastric epithelium expresses Transforming Growth Factor beta1 (TGFβ1), but it is also exposed to luminal peptides that are part of milk. During suckling period, fasting promotes the withdrawal of milk-born molecules while it stimulates gastric epithelial cell proliferation. Such response can be reversed by exogenous TGFβ1, as it directly affects cell cycle through the regulation of p27 levels. We used fasting condition to induce the hyperproliferation of gastric epithelial cells in 14-day-old Wistar rats, and evaluated the effects of TGFβ1 gavage on p27 expression, phosphorylation at threonine 187 (phospho-p27^Thr187) and degradation. p27 protein level was reduced during fasting when compared to suckling counterparts, while phospho-p27^Thr187/p27 ratio was increased. TGFβ1 gavage reversed this response, which was confirmed through immunostaining. By using a neutralizing antibody against TGFβ1, we found that it restored the p27 and phosphorylation levels detected during fasting, indicating the specific role of the growth factor. We noted that neither fasting nor TGFβ1 changed p27 expression, but after cycloheximide administration, we observed that protein synthesis was influenced by TGFβ1. Next, we evaluated the capacity of the gastric mucosa to degrade p27 and we recorded a higher concentration of the remaining protein in pups treated with TGFβ1, suggesting augmented stability under this condition. Thus, we showed for the first time that luminal TGFβ1 increased p27 levels in the rat gastric mucosa by up- regulating translation and reducing protein degradation. We concluded that such mechanisms might be used by rapidly proliferating cells to respond to milk-born TGFβ1 and food restriction.

Decrease expression of microRNA-744 promotes cell proliferation by targeting c-Myc in human hepatocellular carcinoma

Background

MicroRNAs (miRNAs) are a large group of post-transcriptional gene regulators that potentially play a critical role in tumorigenesis. Increasing evidences indicate that miR-744 deregulated in numerous human cancers including hepatocellular carcinoma (HCC). However, its role in HCC carcinogenesis remains poorly defined. In this study, we investigated the roles of miR-744 in tumor growth of HCC.

Methods

Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was conducted to detect the expression of miR-744 and Immunohistochemistry was performed to detect expression of c-Myc in HCC specimens and adjacent normal tissues. The biological functions of miR-744 were determined by cell proliferation and cell cycle assay. Furthermore, cell lines transfected with miR-744 mimics were analyzed in vitro. Luciferase reporter assays was performed to confirm whether miR-744 regulated the expression of c-Myc.

Results

Our results showed that the expression of miR-744 was frequently down-regulated in both HCC tissues and cells. Furthermore, restoration of miR-744 in HCC cells was statistically correlated with decrease of cell growth and restored G1 accumulation. Luciferase assay and Western blot analysis revealed that c-Myc is a direct target of miR-744. Down-regulation of miR-744 and up-regulation of c-Myc were detected in HCC specimens compared with adjacent normal tissues. Moreover, restoration of miR-744 rescues c-Myc induced HCC proliferation.

Conclusions

Our data suggest that miR-744 exerts its tumor suppressor function by targeting c-Myc, leading to the inhibition of HCC cell growth. miR-744 may serve as a potentially useful target for the miRNA-based therapies of HCC in the future.

MicroRNA-196a and -196b as Potential Biomarkers for the Early Detection of Familial Pancreatic Cancer

Screening programs are recommended for individuals at risk (IAR) from families with familial pancreatic cancer (FPC). However, reliable imaging methods or biomarkers for early diagnosis of pancreatic ductal adenocarcinoma (PC) or its precursor lesions are still lacking. The ability of circulating microRNAs (miRNAs) to discriminate multifocal high-grade precursor lesions or PC from normal was examined. The presence of miRNA-21, -155, -196a, -196b and -210 was analyzed in the serum of transgenic KPC mice to test their ability to distinguish mice with different grades of pancreatic intraepithelial neoplasia (mPanIN1–3) or PC from control mice. Serum levels of miR-196a and -196b were significantly higher in mice with PanIN2/3 lesions (n = 10) or PC (n = 8) as compared to control mice (n = 10) or mice with PanIN1 lesions (n = 10; P = .01). In humans, miR-196a and -196b were also diagnostic. Patients with PC, sporadic (n = 9) or hereditary (n = 10), and IAR with multifocal PanIN2/3 lesions (n = 5) had significantly higher serum levels than patients with neuroendocrine pancreatic tumors (n = 10) or chronic pancreatitis (n = 10), IAR with PanIN1 or no PanIN lesions (n = 5), and healthy controls (n = 10). The combination of both miR-196a and -196b reached a sensitivity of 1 and specificity of 0.9 (area under the curve = 0.99) to diagnose PC or high-grade PanIN lesions. In addition, preoperative elevated serum levels of miR-196a and -196b in patients with PC or multifocal PanIN2/3 lesions dropped to normal after potential curative resection. The combination of miR-196a and -196b may be a promising biomarker test for the screening of IAR for FPC.

A systematic review of microRNA expression profiling studies in human gastric cancer

Gastric cancer (GC) is the second leading cause of global cancer mortality. Most GC patients are diagnosed with advanced-stage disease and show extremely poor prognosis. All of the GC research has a common interest to search for the specific and sensitive biomarkers for early diagnosis of GC. Number of microRNAs play important role in GC. We carried out a systematic review of published miRNA profiling studies that compared the miRNA expression profiles between GC tissues and paired noncancerous gastric tissue. A vote-counting strategy was followed with the collection of information like total number of studies reporting differential expression of miRNA, total number of tissue samples used in the studies, direction of differential expression and fold change. A total of 352 differentially expressed microRNAs were reported in the 14 microRNA expression profiling studies that compared GC tissues with normal tissues with 120 microRNAs reported at least in two studies. In the group of consistently reported microRNAs, miR-21 was reported upregulated in 10 studies followed by miR-25, miR-92, and miR-223 upregulated in eight studies. MiR-375 and miR-148a were found downregulated in six and five studies, respectively, followed by miR-638 in four studies. MiR-107 and miR-103 were reported in nine and eight studies, respectively, but their expression were inconsistent. From this study, the most consistently reported upregulated microRNA was found to be miR-21. This systematic review study of human GC microRNA expression profiling studies would provide information on microRNAs with potential role as the biomarkers in gastric cancer.

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.

Comparison of different extraction techniques to profile microRNAs from human sera and peripheral blood mononuclear cells

Background

microRNAs (miRNAs) play crucial roles in major biological processes and their deregulations are often associated with human malignancies. As such, they represent appealing candidates as targets of innovative therapies. Another interesting aspect of their biology is that they are present in various biological fluids where, advantageously, they appear to be very stable. A plethora of studies have now reported their potential as biomarkers that can be used in diagnosis, prognosis and/or theranostic issues. However, the application of circulating miRNAs in clinical practices still requires the identification of highly efficient, robust and reproducible methods for their isolation from biological samples.

In that context, we performed an independent cross-comparison of three commercially available RNA extraction kits for miRNAs isolation from human blood samples (Qiagen and Norgen kits as well as the new NucleoSpin miRNAs Plasma kit from Macherey-Nagel). miRNAs were further profiled using the Taqman Low Density Array technology.

Results

We found that, although these 3 kits had equal performances in extracting miRNAs from peripheral blood mononuclear cells, the Macherey-Nagel kit presented several advantages when isolating miRNAs from sera. Besides, our results have indicated that, depending on the quantity of the biological samples used, the extraction procedure directly impacted on the G/C composition of the miRNAs detected.

Conclusion

Overall, our study contributes to the definition of a reliable framework for profiling circulating miRNAs.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-395) contains supplementary material, which is available to authorized users.

MicroRNA in gastrointestinal cancer: a step closer to reality

Despite significant strides in understanding molecular pathogenesis of cancer, gastrointestinal malignancy (gastric, colorectal, pancreatic, and liver) still ranks among the leading causes of cancer-related mortality and morbidity worldwide. One of the key clinical challenges in effectively reducing disease burden associated with gastrointestinal neoplasia stems from late diagnosis, underscoring the need for early detection, risk assessment, and intervention. Currently available screening approaches are inadequate, and the development of accurate noninvasive molecular biomarkers is very much needed, microRNAs (miRNAs) are short (20-24 nucleotides in length) noncoding RNAs that have emerged as important translational gene regulators in cancer cells. In contrast to genetic markers, miRNAs have a cancer-specific expression pattern. They are present in a remarkably stable form and can be detected in a wide variety of body fluids including blood and feces. These properties make them attractive cancer biomarker targets. Although development of miRNA biomarkers is still in its early stages, burgeoning evidence supports their potential use for development as markers for early detection, prognosis, and prediction of disease recurrence and therapeutic outcome in gastrointestinal cancers. In the future, it is likely that miRNA biomarkers will revolutionize personalized medicine and mitigate disease burden associated with gastrointestinal cancers.

Identification of circulating microRNAs as novel potential biomarkers for gastric cancer detection: a systematic review and meta-analysis

BACKGROUND

Recent studies show that microRNAs (miRNAs) in serum or plasma can be stably detected and used as potential biomarkers in cancer diagnosis.

OBJECTIVES

To systematically evaluate circulating miRNAs from numerous gastric cancer (GC) expression profiling studies and to determine miRNA biomarkers for GC detection.

METHODS

A systematic review and meta-analysis of published studies comparing the circulating miRNA expressions between GC patients and healthy controls were carried out. An miRNA ranking system that considered the number of comparisons in agreement, total number of samples, and average fold change was used. Then the receiver-operating characteristic curve (ROC) results of the top miRNAs were combined to further evaluate their diagnostic value by using Meta-disc 1.4.

RESULTS

A total of 35 miRNAs were reported in the 22 included studies, with 7 miRNAs reported in at least 2 studies. MiR-21 is the most consistently reported miRNA with upregulation. In further analysis, the sensitivity, specificity, and area under the curve of summary ROC for miR-21 in GC diagnosis are 0.78 (95 % CI 0.71-0.85), 0.89 (95 % CI 0.82-0.94), and 0.91, respectively.

CONCLUSION

Circulating miR-21 can serve as a potential biomarker for detection of GC.

Liquid biopsy of gastric cancer patients: Circulating tumor cells and cell-free nucleic acids

To improve the clinical outcomes of cancer patients, early detection and accurate monitoring of diseases are necessary. Numerous genetic and epigenetic alterations contribute to oncogenesis and cancer progression, and analyses of these changes have been increasingly utilized for diagnostic, prognostic and therapeutic purposes in malignant diseases including gastric cancer (GC). Surgical and/or biopsy specimens are generally used to understand the tumor-associated alterations; however, those approaches cannot always be performed because of their invasive characteristics and may fail to reflect current tumor dynamics and drug sensitivities, which may change during the therapeutic process. Therefore, the importance of developing a non-invasive biomarker with the ability to monitor real-time tumor dynamics should be emphasized. This concept, so called “liquid biopsy”, would provide an ideal therapeutic strategy for an individual cancer patient and would facilitate the development of “tailor-made” cancer management programs. In the blood of cancer patients, the presence and potent utilities of circulating tumor cells (CTCs) and cell-free nucleic acids (cfNAs) such as DNA, mRNA and microRNA have been recognized, and their clinical relevance is attracting considerable attention. In this review, we discuss recent developments in this research field as well as the relevance and future perspectives of CTCs and cfNAs in cancer patients, especially focusing on GC.

Role of miR-191/425 cluster in tumorigenesis and diagnosis of gastric cancer

Gastric cancer (GC) is among the most frequent types of cancer worldwide. Therefore, understanding the biology of GC tumorigenesis is important for appropriate diagnosis and patient surveillance. The miR-191/425 cluster has been reported to be overexpressed in various human cancers, but the tumorigenic role and clinical significance of miR-191/425 overexpression in gastric carcinogenesis is currently undefined. In this study, the expression of miR-191 and miR-425 in GC tissue and serum was assessed, and the relationship between miRNA expression and clinicopathological data was analyzed. We found that miR-191 and miR-425 were both significantly increased in human GC tissues relative to adjacent normal controls. In addition, miR-191 levels correlated with GC tumor stage and metastatic state. Furthermore, the level of serum miR-191 was significantly higher in the GC group than in the control group when using serum miR-16 as an endogenous control. Finally, inhibition of miR-191 or miR-425 in the GC cell lines HGC-27 not only reduced cell proliferation and cell cycle progression but also impaired cell migration and invasion. Taken together, our results revealed the oncogenic roles of miR-191 and miR-425 in gastric carcinogenesis, and indicated the potential use of serum miR-191 as a novel and stable biomarker for GC diagnosis.

Serum protein and genetic tumor markers of gastric carcinoma

The high incidence of gastric cancer and consequent mortality pose severe threats to human health. Early screening, diagnosis and treatment are the key to improve the prognosis of the patients with gastric cancer. Gastroscopy with biopsy is an efficient method for the diagnosis of early gastric cancer, but the associated discomfort and high cost make it difficult to be a routine method for screening gastric cancer. Serum tumor marker assay is a simple and practical method for detection of gastric cancer, but it is limited by poor sensitivity and specificity. Therefore, people have been looking for novel serum markers of gastric cancer in recent years. Here we review the novel serum tumor markers of gastric cancer and their diagnostic significance, focusing on the discoveries from serum proteomics analyses and epigenetics researches.

Plasma miR-122 and miR-192 as potential novel biomarkers for the early detection of distant metastasis of gastric cancer

The aim of the present study was to ascertain whether plasma levels of specific microRNAs (miRNAs) are associated with distant metastasis (DM) in gastric cancer (GC). miRNA profiling was performed on 12 pairs of samples of gastric cancer with distant metastasis (GC/DM) and gastric cancer with no distant metastasis (GC/NDM); 14 differentially expressed miRNAs were identified for further inspection. Validation of these 14 miRNAs using quantitative reverse transcription PCR (qRT-PCR) on an independent validation set identified 2 differentially expressed miRNAs (miR-122 and miR-192). further validation of these two candidate miRNAs was conducted in a disease control set, a self-paired plasma set and finally in gastric cell lines in vitro. The results revealed that when compared with GC/NDM and healthy controls (HCs), plasma levels of miR-122 were significantly lower and plasma levels of miR-192 were significantly higher in GC/DM samples (both P<0.01). The plasma miR-122 level was again lower and the plasma miR-192-level was again higher in patients with GC/DM than in patients with benign gastric ulcer (BGC) and chronic gastritis (CG) (P<0.01). Compared to the level in patients with pre-distant metastases, miR-122 was significantly decreased while miR-192 was markedly elevated in patients with post-distant metastases (P<0.01). In CTC105 and CTC141 cells, miR-122 levels were moderately lower and miR-192 levels were markedly higher when compared to the levels in the GES-1 cells. ROC analyses showed that the AUC for plasma miR-122 was 0.808 (95% CI, 0.712-0.905; P<0.01), and the AUC for plasma miR-192 was 0.732 (95% CI, 0.623-0.841; P<0.01) for distinguishing GC/DM from GC/NDM. High expression of miR-122 in plasma independently contributed to a more favorable prognosis for GC (hazard ratio, 0.262; 95% CI, 0.164-0.816; P=0.038; Cox regression analysis), whereas the miR-192 level was not associated with the overall survival time. Our results demonstrated that assessment of decreased circulating miR-122 and elevated circulating miR-192 levels has the potential to improve early detection of DM in GC. Higher plasma levels of miR-122 in GC may indicate a favorable prognosis.

Advances in molecular biomarkers for gastric cancer: miRNAs as emerging novel cancer markers

Carcinoma of the stomach is one of the most prevalent cancer types in the world. Although the incidence of gastric cancer is declining, the outcomes of gastric cancer patients remain dismal because of the lack of effective biomarkers to detect early gastric cancer. Modern biomedical research has explored many potential gastric cancer biomarker genes by utilising serum protein antigens, oncogenic genes or gene families through improving molecular biological technologies, such as microarray, RNA-Seq and the like. Recently, the small noncoding microRNAs (miRNAs) have been suggested to be critical regulators in the oncogenesis pathways and to serve as useful clinical biomarkers. This new class of biomarkers is emerging as a novel molecule for cancer diagnosis and prognosis, including gastric cancer. By translational suppression of target genes, miRNAs play a significant role in the gastric cancer cell physiology and tumour progression. There are potential implications of previously discovered gastric cancer molecular biomarkers and their expression modulations by respective miRNAs. Therefore, many miRNAs are found to play oncogenic roles or tumour-suppressing functions in human cancers. With the surprising stability of miRNAs in tissues, serum or other body fluids, miRNAs have emerged as a new type of cancer biomarker with immeasurable clinical potential.

Screening and identification of six serum microRNAs as novel potential combination biomarkers for pulmonary tuberculosis diagnosis

BACKGROUND

It is very difficult to prevent pulmonary tuberculosis (TB) due to the lack of specific and diagnostic markers, which could lead to a high incidence of pulmonary TB. We screened the differentially expressed serum microRNAs (miRNAs) as potential biomarkers for the diagnosis of pulmonary TB.

METHODS

In this study, serum miRNAs were screened using the Solexa sequencing method as the potential biomarkers for the diagnosis of pulmonary TB. The stem-loop quantitative reverse-transcription polymerase chain reaction (qRT-PCR) assay was used to verify differentially expressed serum miRNAs. The receiver operating characteristic (ROC) curve and logistic regression model were used to analyze the sensitivity and specificity of the single miRNA and a combination of miRNAs for diagnosis, respectively. Using the predicted target genes, we constructed the regulatory networks of miRNAs and genes that were related to pulmonary TB.

RESULTS

The Solexa sequencing data showed that 91 serum miRNAs were differentially expressed in pulmonary TB patients, compared to healthy controls. Following qRT-PCR confirmation, six serum miRNAs (hsa-miR-378, hsa-miR-483-5p, hsa-miR-22, hsa-miR-29c, hsa-miR-101 and hsa-miR-320b) showed significant difference among pulmonary TB patients, healthy controls (P<0.001) and differential diagnosis groups (including patients with pneumonia, lung cancer and chronic obstructive pulmonary disease) (P<0.05). The logistic regression analysis of a combination of six serum miRNAs revealed that the sensitivity and the specificity of TB diagnosis were 95.0% and 91.8% respectively. The miRNAs-gene regulatory networks revealed that several miRNAs may regulate some target genes involved in immune pathways and participate in the pathogenesis of pulmonary TB.

CONCLUSION

Our study suggests that a combination of six serum miRNAs have great potential to serve as non-invasive biomarkers of pulmonary TB.

MicroRNA and mRNA signatures in ischemia reperfusion injury in heart transplantation

Ischemia reperfusion (I/R) injury is an unavoidable event occurring during heart transplantation, leading to graft failures and lower long-term survival rate of the recipient. Several studies have demonstrated that microRNAs (miRNAs) are vital regulators of signalling pathways involved in I/R injury. The present study aims to quantify the altered expression levels of miRNA and mRNA upon I/R injury in a mouse heart transplantation model, and to investigate whether these miRNA can regulate genes involved in I/R injury. We performed heterotopic heart transplantation on mouse models to generate heart tissue samples with I/R and non-I/R (control). The expression levels of miRNAs as well as genes were measured in heart grafts by microarray and real time RT-PCR. miRNA alteration in cardiomyocytes exposed to hypoxia was also detected by qRT-PCR. We observed significant alterations in miRNA and gene expression profile after I/R injury. There were 39 miRNAs significantly downregulated and 20 upregulated up to 1.5 fold in heart grafts with I/R injury compared with the grafts without I/R. 48 genes were observed with 3 fold change and p<0.05 and 18 signalling pathways were enriched using Keggs pathway library. Additionally, hypoxia/reperfusion induced primary cardiomyocyte apoptosis and altered miRNA expression profiles. In conclusion, this is the first report on miRNA expression profile for heart transplantation associated with I/R injury. These findings provide us with an insight into the role of miRNA in I/R injury in heart transplantation.

A pilot study assessing the incidence and clinical significance of circulating tumor cells in esophagogastric cancers

BACKGROUND

Circulating tumor cells (CTCs) have been found to be of clinical utility in predicting response to treatment and prognosis in several malignancies. Less is known of the prevalence and clinical relevance of CTCs in esophagogastric adenocarcinoma, with the available data arising from heterogeneous patient populations using varied detection methods.

PATIENTS AND METHODS

A pilot study was undertaken to assess the prevalence of CTCs in patients with advanced esophageal or gastric adenocarcinoma. Patients were eligible if they had advanced disease and either had received no prior therapy or had progressed after prior chemotherapy. Blood samples for CTC analysis were obtained at baseline and during the course of treatment. The CellSearch immunomagnetic CTC detection platform was used.

RESULTS

Twenty-two patients with metastatic esophageal or gastric adenocarcinoma were enrolled. Eighteen received first-line EOX (epirubicin/oxaliplatin/capecitabine) chemotherapy (± panitumumab) and had baseline samples suitable for CTC analysis. At baseline, ≥ 2 CTCs were detected in 8 patients (44%). Overall tumor response rate was 60% in patients with < 2 CTCs and 37.5% in patients with ≥ 2 CTCs. Median progression-free and overall survival were 6.1 and 10.5 months and 5.2 and 6.1 months in the groups of patients with < 2 CTCs and ≥ 2 CTCs, respectively. The study was prematurely discontinued, owing to the withdrawal of commercial support.

CONCLUSION

The incidence of CTCs in locally advanced or metastatic esophagogastric cancer may be clinically relevant. Investigation of the potential clinical utility of CTCs is warranted in a larger cohort of patients with esophagogastric cancer.

Identification of serum miRNAs as novel non-invasive biomarkers for detection of high risk for early gastric cancer

BACKGROUND

Many micro-RNAs (miRNAs) are differentially expressed in Helicobacter pylori-infected gastric mucosa and in gastric cancer tissue and previous reports have suggested the possibility of serum miRNAs as complementary tumour markers. The aim of the study was to investigate serum miRNAs and pepsinogen levels in individuals at high risk for gastric cancer both before and after H. pylori eradication.

METHODS

Patients with recent history of endoscopic resection for early gastric cancer and the sex- and age-matched controls were enrolled. Serum was collected from subjects before or after eradication and total RNA was extracted to analyse serum levels of 24 miRNAs. Serum pepsinogen (PG) I and II levels were measured using enzyme-linked immunosorbent assay kits.

RESULTS

Using miR-16 as an endogenous control, the relative levels of miR-106 and let-7d before and after H. pylori eradication and miR-21 after eradication were significantly higher in the high-risk group than in the controls. H. pylori eradication significantly decreased miR-106b levels and increased let-7d only in the control group. After eradication, the combination MiR-106b with miR-21 was superior to serum pepsinogen and the most valuable biomarker for the differentiating high-risk group from controls.

CONCLUSION

Serum miR-106b and miR-21 may provide a novel and stable marker of increased risk for early gastric cancer after H. pylori eradication.

Gastric cancer: epidemiologic aspects

A multifactorial and multistep model of gastric cancer (GC) is currently accepted, according to which different environmental and genetic factors are involved at different stages in the cancer process. The aim of this article is to review the most relevant information published on the relative contribution of genetic and environmental factors. Large meta-analyses confirmed the association between IL8, IL10, TNF-b, TP53 and PSCA, while genetic variation at different genes such as XPG, PLCE1, HFE, ERCC5, EZH2, DOC2, CYP19A1, ALDH2, and CDH1 have been reported to be associated with GC risk. Several microRNAs have also been associated with GC and their prognosis. Cohort studies have shown the association between GC and fruit, flavonoid, total antioxidant capacity, and green tea intake. Obesity was associated with cardia GC, heme iron intake from meat with GC risk. Several large meta-analyses have confirmed the positive association of GC with salt intake and pickled foods and the negative association with aspirin use.

Making sense of OMICS data in population-based environmental health studies

Although experience from the application of OMICS technologies in population-based environmental health studies is still relatively limited, the accumulated evidence shows that it can allow the identification of features (genes, proteins, and metabolites), or sets of such features, which are targeted by particular exposures or correlate with disease risk. Such features or profiles can therefore serve as biomarkers of exposure or disease risk. Blood-based OMIC profiles appear to reflect to some extent events occurring in target tissues and are associated with toxicity or disease and therefore have the potential to facilitate the elucidation of exposure-disease relationships. Further progress in this direction requires better understanding of the significance of exposure-induced network perturbations for disease initiation and progression and the development of a framework that combines agnostic searches with the utilization of prior knowledge, taking account of particular elements which characterize the structure and evolution of complex systems and brings in principles of systems biology.

Profiling of circulating microRNAs after a bout of acute resistance exercise in humans

Recent studies have revealed a new aspect of physiological regulation in which microRNAs (miRNAs) play fundamental roles in diverse biological and pathological processes. Furthermore, it was recently discovered that miRNAs are stably secreted into blood and that circulating miRNAs may play important roles in cell-cell communication. Here, we examined whether the circulating miRNA profile is affected by acute resistance exercise. Twelve males performed a resistance exercise session (bench press and leg press), consisting of five sets of 10 repetitions at 70% of maximum strength, with a 1 min rest between sets. Blood samples were taken before exercise, and at 0 and 60 min, 1 day, and 3 days after exercise. The circulating miRNA profile was determined by microarray analysis. Quantitative real-time PCR confirmed that the miR-149* level increased three days after resistance exercise. In contrast, the miR-146a and miR-221 levels decreased three days after resistance exercise. Our findings suggest that circulating miRNA levels change in response to acute resistance exercise, and miRNAs may play important roles in resistance-exercise-induced adaptation.

The potential role of miR-451 in cancer diagnosis, prognosis, and therapy

MicroRNAs (miRNA) are small noncoding RNAs that converge to maintain an intrinsic balance of various processes, including cell proliferation, differentiation, and apoptosis. Recent research efforts have been devoted to translating these basic discoveries into applications that could improve the early diagnosis and therapeutic outcome of patients with cancer. Early studies have shown that miRNA-451 (miR-451) is widely dysregulated in human cancers and plays a critical role in tumorigenesis and tumor progression. In this review, we summarize the potential use of miR-451 for cancer diagnosis, prognosis, and treatment. In addition, we discuss the possible mechanisms of miR-451 dysregulation and future challenges in development of miR-451 as a noninvasive biomarker and a potential therapeutic target in human cancers.

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.

Reduced expression of miR-22 in gastric cancer is related to clinicopathologic characteristics or patient prognosis

Objective

Involvements of microRNA-22 (miR-22) in cancer development have attracted much attention, but its role in tumorigenesis of gastric cancer is still largely unknown. Therefore, the aim of this study was to investigate the expression patterns and clinical implications of miR-22 in gastric cancer.

Methods

Quantitative RT-PCR was performed to evaluate the expression levels of miR-22 in 98 pairs of gastric cancer and normal adjacent mucosa.

Results

Compared with normal adjacent mucosa, miR-22 expression was significantly downregulated in gastric cancer tissues (P < 0.001). Of 98 patients with gastric cancer, 58 (59.2%) were placed in the low miR-22 expression group and 40 (40.8%) were placed in the high miR-22 expression group. In addition, tumors with low miR-22 expression had greater extent of lymph node metastasis (P = 0.02) and distant metastasis (P = 0.01), and were at a worse stage (P = 0.01) than the tumors with high miR-22 expression. Moreover, the gastric cancer patients with low miR-22 expression had shorter overall survival than those with high miR-22 expression (P = 0.03). MiR-22, determined by multivariate analysis, was an independent prognostic factor for patients with gastric cancer.

Conclusion

Our data offer the convincing evidence that the reduced expression of miR-22 was significantly associated with malignant development of gastric cancer and may be a novel prognostic marker of this disease. miR-22 might have potentials in the application of cancer therapy for patients with 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.

Up-regulation of Ago2 expression in gastric carcinoma

Argonaute (Ago) proteins have been demonstrated to be widely expressed and involved in post-transcriptional gene silencing and thus play key roles in carcinogenesis. Nevertheless, little is known about the specific role of Ago2 in gastric cancer (GC). Thus, we aimed to study the expression of Ago2 in 363 primary GC, 8 corresponding lymph node metastases and 10 non-neoplastic surrounding gastric epithelium tissues by immunohistochemical analyses and tissue microarray. The expression of Ago2 was also correlated with clinicopathological characteristics and HER-2 status. Ago2 expression levels in primary GC and corresponding lymph node metastases were significantly higher compared with healthy controls (P < 0.05). But, there was no difference of Ago2 between GC and its metastatic lymph node (P > 0.05). Ago2 up-regulation had no correlation with GC patients' age, tumor location, tumor size, gross morphology or tumor infiltration. However, we found that Ago2 was different between HER-2 positive and HER-2 negative groups (P = 0.044), which had been demonstrated to be related to GC prognosis. And there was a great correlation between Ago2 expression and the tumor differentiation (P = 0.007), lymph node invasion (P = 0.000) and clinical stage (P = 0.006). Interestingly, Ago2 was also correlated to patients' gender (P = 0.004), which may suggest a possible role of hormonal signal in the mechanisms of Ago2. Thus, our results suggested that up-regulation of Ago2 may play an important role in GC carcinogenesis and progression. Further studies on the cellular functions of Ago2 need to address these issues.

MiRNA-199a-3p: A potential circulating diagnostic biomarker for early gastric cancer

BACKGROUND

Tumor-associated miRNAs have been detected in serum or plasma. We investigated whether plasma miRNA-199a-3p could be a potential circulating biomarker for early gastric cancer (EGC).

METHODS

By using real-time qRT-PCR, the expression of miRNA-199a-3p were compared between these pre-operative plasmas from 30 EGC patients and 70 healthy controls, and between these pre-operative and post-operative plasmas. Further validation was on an independent set of plasmas from 50 EGC patients.

RESULTS

The expression of miRNA-199a-3p (47.5 ± 6.5) in plasma in EGC patients was significantly higher than that from healthy controls (13.9 ± 2.7, P < 0.001) and gastric precancerous diseases (GPD) patients (19.2 ± 2.5, P = 0.004), respectively. Furthermore, the expression levels of miRNA-199a-3p (11.8 ± 2.9, P = 0.012) in the post-operative plasmas were significantly reduced when compared to the pre-operative plasmas. With respect of clinicopathological characteristics, the expression of miRNA-199a-3p in plasma was not associated with the depth of tumor invasion. Moreover, the AUC of the expression of miRNA-199a-3p in plasma for EGC diagnosis was 0.818, which was significantly higher than that of combined tumor markers (0.556). The sensitivity, specificity and accuracy of miRNA-199a-3p expression in plasma for EGC diagnosis were 76%, 74%, and 75%, respectively.

CONCLUSIONS

Plasma miRNA-199a-3p could be a novel potential diagnostic biomarkers for EGC.

Proto-oncogenic isoform A2 of eukaryotic translation elongation factor eEF1 is a target of miR-663 and miR-744

Background:

Eukaryotic translation elongation factor 1A2 (eEF1A2) is a known proto-oncogene. We proposed that stimulation of the eEF1A2 expression in cancer tissues is caused by the loss of miRNA-mediated control.

Methods:

Impact of miRNAs on eEF1A2 at the mRNA and protein levels was examined by qPCR and western blot, respectively. Dual-luciferase assay was applied to examine the influence of miRNAs on 3′-UTR of EEF1A2. To detect miRNA-binding sites, mutations into the 3′-UTR of EEF1A2 mRNA were introduced by the overlap extension PCR.

Results:

miR-663 and miR-744 inhibited the expression of luciferase gene attached to the 3′-UTR of EEF1A2 up to 20% and 50%, respectively. In MCF7 cells, overexpression of miR-663 and miR-744 reduced the EEF1A2 mRNA level by 30% and 50%. Analogous effects were also observed at the eEF1A2 protein level. In resveratrol-treated MCF7 cells the upregulation of mir-663 and mir-744 was accompanied by downregulation of EEF1A2 mRNA. Both miRNAs were able to inhibit the proliferation of MCF7 cells.

Conclusion:

miR-663 and miR-744 mediate inhibition of the proto-oncogene eEF1A2 expression that results in retardation of the MCF7 cancer cells proliferation. Antitumour effect of resveratrol may include stimulation of the miR-663 and miR-744 expression.

Genetic polymorphisms of miR-146a and miR-27a, H. pylori infection, and risk of gastric lesions in a Chinese population

Background

MicroRNAs (miRNAs) have been implicated in various human diseases. Single nucleotide polymorphisms (SNPs) in inflammation-related miRNA may play an important role in Helicobacter pylori (H. pylori)-induced gastric lesions. To evaluate the associations between miRNA SNPs, H. pylori and gastric lesions, a population-based study was conducted in Linqu County, China.

Methodology/Principal Findings

Based on serum miRNA array conducted in this population, two SNP loci (miR-146a rs2910164: G>C and miR-27a rs895819: T>C) were determined by polymerase chain reaction-restriction fragment length polymorphism in 2,380 participants with diverse gastric lesions. Using participants with superficial gastritis and mild chronic atrophic gastritis as the reference group, we found that rs2910164 CC carriers had a significantly increased risk of intestinal metaplasia [adjusted odds ratio (OR), 1.42; 95% confidence interval (CI), 1.03–1.97] and dysplasia (OR, 1.54; 95% CI, 1.05–2.25) compared to GG carriers, whereas no significant association was observed for rs895819. Stratified analysis by H. pylori infection indicated that rs2910164 C allele was associated with an increased risk of intestinal metaplasia and dysplasia only among individuals infected with H. pylori (CC vs. GG: OR, 1.53; 95% CI, 1.12–2.08, P for trend = 0.004). Participants who simultaneously carried variant alleles and H. pylori infection were more likely to develop intestinal metaplasia and dysplasia, although the interaction between genetic variants and H. pylori infection was not significant (P for interaction = 0.35 for rs2910164 and 0.92 for rs895819).

Conclusions/Significance

These findings suggest that miR-146a rs2910164 polymorphism may contribute to the evolution of H. pylori-associated gastric lesions in this high-risk population.

Clinical application of microRNA in gastric cancer in Eastern Asian area

Recent research has shown that microRNA (miRNA), which is involved in almost every step of gastric carcinogenesis, has broad prospective application in diagnosis and therapy of gastric carcinoma. Eastern Asia (South Korea, Japan and China) has the highest incidence of gastric cancer in the world. There were 988  000 new cases of gastric cancer worldwide and 736  000 deaths in 2008. Approximately 60% of the cases of gastric cancer are found in East Asia (mainly China). We herein provide a brief review of the clinical applications of miRNA, which include the following aspects: (1) miRNA may serve as a potential new generation of tumor markers; (2) a complete miRNA expression profile is highly specific, can reflect the evolutionary lineage and differentiation of tumors, and be used to carry out diversity analysis; (3) detecting specific miRNA expression in peripheral blood will become a new method for diagnosis of gastric cancer; (4) miRNA can predict prognosis of gastric cancer; (5) miRNA has predictive value in determining chemotherapy and radiotherapy resistance; and (6) miRNA could be a type of innovative drug. Finally, we focus on assessing the value of miRNA from laboratory to clinical application and the challenges it faces in East Asia.

miRConnect 2.0: identification of oncogenic, antagonistic miRNA families in three human cancers

BACKGROUND

Based on their function in cancer micro(mi)RNAs are often grouped as either tumor suppressors or oncogenes. However, miRNAs regulate multiple tumor relevant signaling pathways raising the question whether two oncogenic miRNAs could be functional antagonists by promoting different steps in tumor progression. We recently developed a method to connect miRNAs to biological function by comparing miRNA and gene array expression data from the NCI60 cell lines without using miRNA target predictions (miRConnect).

RESULTS

We have now extended this analysis to three primary human cancers (ovarian cancer, glioblastoma multiforme, and kidney renal clear cell carcinoma) available at the Cancer Genome Atlas (TCGA), and have correlated the expression of the clustered miRNAs with 158 oncogenic signatures (miRConnect 2.0). We have identified functionally antagonistic groups of miRNAs. One group (the agonists), which contains many of the members of the miR-17 family, correlated with c-Myc induced genes and E2F gene signatures. A group that was directly antagonistic to the agonists in all three primary cancers contains miR-221 and miR-222. Since both miR-17 ~ 92 and miR-221/222 are considered to be oncogenic this points to a functional antagonism of different oncogenic miRNAs. Analysis of patient data revealed that in certain patients agonistic miRNAs predominated, whereas in other patients antagonists predominated. In glioblastoma a high ratio of miR-17 to miR-221/222 was predictive of better overall survival suggesting that high miR-221/222 expression is more adverse for patients than high miR-17 expression.

CONCLUSION

miRConnect 2.0 is useful for identifying activities of miRNAs that are relevant to primary cancers. The new correlation data on miRNAs and mRNAs deregulated in three primary cancers are available at miRConnect.org.

Circulating microRNAs as biomarkers for early detection of diffuse-type gastric cancer using a mouse model

Background:

Diffuse-type gastric cancer (DGC) exhibits rapid disease progression and a poor prognosis. There are no effective serum biomarkers for early detection of DGC. We have established an E-cadherin/p53 double conditional knockout (DCKO) mouse line that recapitulates human DGC morphologically and molecularly. In this study we tried to identify circulating microRNAs (miRNAs) as non-invasive biomarkers for DGC diagnosis using DCKO mice.

Methods:

We performed miRNA microarray and quantitative reverse transcription–PCR analyses of tissue and serum samples from DCKO mice with DGC and age-matched littermate controls.

Results:

Comparative analyses showed that mouse and human primary gastric cancers have similar miRNA expression patterns. Next, we selected some candidate miRNAs highly expressed in sera and cancer tissues of DCKO mice for further evaluation. TaqMan quantitative RT–PCR analyses indicated that four of them, miR-103, miR-107, miR-194 and miR-210, were significantly upregulated in sera of both early and advanced-stage DGC-bearing mice compared with in corresponding controls. Receiver-operating characteristic curve analyses demonstrated that these four miRNAs can discriminate DGC-positive cases from normal ones with high sensitivity and specificity.

Conclusion:

These observations suggest that this mouse model of DGC is useful for identifying serum biomarkers, and we found circulating miRNAs that can accurately detect DGC at an early stage.

The role of microRNAs in cancers of the upper gastrointestinal tract

Cancers of the oesophagus, gastro-oesophageal junction and stomach (upper gastrointestinal tract cancers; UGICs) pose a major health risk around the world. Collectively, the 5-year survival rate has remained <15%, and therapeutic improvements have been very slow and small. Novel molecules for early diagnosis, prognosis and therapy are, therefore, urgently needed. The role that microRNA (miRNA) molecules have in UGICs are worth pursuing to this end. miRNAs are small noncoding RNA molecules that regulate ∼60% of coding genes in humans and, therefore, are pivotal in mediating and regulating many physiologic processes. miRNAs are deregulated in many disease states, particularly in cancer, making them important targets. Here, we review the growing body of evidence regarding the alterations of miRNAs in UGICs. By suppressing translation and/or promoting degradation of mRNAs, miRNAs can contribute to carcinogenesis and progression of UGICs. In-depth studies of miRNAs in UGICs might yield novel insights and potential novel therapeutic strategies.

Plasma microRNAs serve as novel potential biomarkers for early detection of gastric cancer

Recent studies have shown that microRNAs can be stably detected in human plasma and have the potential as non-invasive biomarkers for the diagnosis of cancers. This study evaluates the potential application of plasma microRNAs for the early detection of gastric cancer (GC). We first measured the plasma expression levels of 15 selected microRNAs (miR-1, -106a, -106b, -17-5p, -20a, -21, -221, -27a, -34, -376c, -378, -423-5p, -451, -486, -744) in 30 GC patients and 30 age- and gender-matched healthy controls and then validated those microRNAs that differentiating GC and controls in another 60 GC patients and 60 matched controls using quantitative reverse transcription-polymerase chain reaction. The areas under the receiver operating characteristic (ROC) curves were used to test the sensitivity and specificity of GC diagnosis using these identified plasma microRNAs. Three plasma microRNAs, miR-106b, miR-20a, and miR-221, were significantly elevated in GC patients than in healthy controls (P < 0.05). Furthermore, the areas under the ROC curves using miR-106b, miR-20a, and miR-221 for GC diagnosis were 0.7733 (95 % CI, 0.7758-0.8409), 0.8593 (95 % CI, 0.8046-0.9139), and 0.7960 (95 % CI, 0.7256-0.8664), respectively. Furthermore, these three microRNAs had a statistically significant elevation in GC patients compared with healthy controls at each of the four stages. However, there were no significant differences in the plasma levels of the three microRNAs among the four TNM stages (P > 0.05). Plasma miR-106b, miR-20a, and miR-221 have the potential as novel, non-invasive biomarkers for the early detection of GC.

MicroRNA: A Bridge from H. pylori Infection to Gastritis and Gastric Cancer Development

Helicobacter pylori (H. pylori) infection is a recognized risk factor for gastric cancer. The disease is one of the most common in the world and explains for a significant number of cancer cases and cancer-associated deaths worldwide. H. pylori infection induces huge array of responses at the gastric epithelial cells and the immune system, inducing both pro- and anti-inflammatory molecules that are intended to either perpetuate or control the infection. Despite the strong immune response, the infection is not cleared and can persist mostly without causing major significant discomfort in the human host. Among the mediators induced in response to the infection, microRNA (miRNA) have the potential to play a major impact on the outcome of the bacteria-host interaction. These miRNA are small 18-24 nucleotide long nucleotide molecules that can interact with mRNA molecules and block their translation into proteins or induce their degradation. Many efforts have been put into the generation of miRNA profiles and their role in gastric cancer. This has led to the identification of miRNA associated with promoting the inflammatory response initiated by the H. pylori infection, increasing the malignant progression of the gastric epithelium, and enhancing the invasiveness and migratory capacity of cancer cells. However, at the same time, several miRNA have been associated with events that are totally opposite, leading to reduced inflammation, inhibition of malignancy and increased apoptosis of transformed cells. In summary, as it is in many other examples, the role played by miRNA in gastric cancer is the results of a delicate balance between pro- and anti-cancer miRNA, and this balance is modified by the interaction of many players, many of which are still waiting to be discovered.

Determination of plasma microRNA for early detection of gastric cancer

Gastric cancer is the fourth most prevalent malignancy worldwide and remains the second most common cause of cancer-related death globally. Understanding the molecular structure of gastric carcinogenesis might identify new diagnostic and therapeutic strategies for this disease. Thus, early detection of gastric cancer is a key measure to reduce the mortality and improve the prognosis of gastric cancer. There have recently been several reports that microRNAs (miRNAs) circulate in highly stable, cell-free forms in blood. Because serum and plasma miRNAs are relatively easy to access, circulating miRNAs also have great potential to serve as non-invasive biomarkers. Although a number of miRNAs associated with gastric cancer have been identified, the underlying mechanism of these miRNAs in tumorigenesis and tumor progression remains to be investigated. The purpose of this study is to identify the potential of serum miRNAs as biomarkers for early detection of gastric cancer patients. RNA was isolated using the High Pure miRNA Isolation Kit (Roche) following the manufacturer's protocol. cDNA and preamplification protocols were obtained from the isolated plasma miRNAs. The BioMark™ 96.96 Dynamic Array (Fluidigm Corporation) for real-time qPCR was used to simultaneously quantite the expression of 740 miRNAs. All statistical analyses were performed using the Biogazelle's qbase PLUS 2.0 software. In this study, among 740 miRNAs that we analyzed only miR-195-5p was significantly (p < 0.05, fold changes = 13, 3) down-regulated in gastric cancer patients compared with control. We demonstrated that miR-195-5p is a novel tumor suppressor miRNA and may contribute to gastric carcinogenesis. The miRNA expression profile described in this study should contribute to future studies on the role of miRNAs in gastric cancer.

Discrimination of gastric cancer from normal by serum RNA based on surface-enhanced Raman spectroscopy (SERS) and multivariate analysis

PURPOSE

Here, the authors explore the feasibility of discriminating cancer patients from healthy controls by serum RNA detection based on surface-enhanced Raman spectroscopy (SERS) and multivariate analysis.

METHODS

MgSO(4)-aggregated silver nanoparticles (Ag NP) as the SERS-active substrate presented strong SERS signals to RNA. SERS measurements were performed on two groups of serum RNA samples: one group from patients (n = 31) with gastric cancer and the other group from healthy volunteers (n = 34).

RESULTS

Tentative assignments of the Raman bands in the normalized SERS spectra demonstrated that there are differential expressions of circulating RNA between the gastric cancer group and the control group. Principal component analysis (PCA) combined with linear discriminate analysis (LDA) was introduced to differentiate gastric cancer from normal and achieved sensitivity of 100% and specificity of 94.1%.

CONCLUSIONS

This exploratory study demonstrated potential for developing serum RNA SERS analysis into a useful clinical tool for noninvasive screening and detection of cancer.

Circulating microRNAs in plasma as early detection markers for breast cancer

In recent years, circulating miRNAs have attracted a great deal of attention as promising novel markers for various diseases. Here, we investigated their potential to serve as minimally invasive, early detection markers for breast cancer in blood plasma. We profiled miRNAs extracted from the plasma of early stage breast cancer patients (taken at the time-point of diagnosis) and healthy control individuals using TaqMan low-density arrays (TLDA). Selected candidates identified in the initial screen were further validated in an extended study cohort of 207 individuals including 127 sporadic breast cancer cases and 80 healthy controls via RT-qPCR. Four miRNAs (miR-148b, miR-376c, miR-409-3p and miR-801) were shown to be significantly upregulated in the plasma of breast cancer patients. ROC curve analysis showed that the combination of only three miRNAs (miR-148b, miR-409-3p and miR-801) had an equal discriminatory power between breast cancer cases and healthy controls as all four miRNAs together (AUC = 0.69). In conclusion, the identified miRNAs might be of potential use in the development of a multimarker blood-based test to complement and improve early detection of breast cancer. Such a multimarker blood test might for instance provide a prescreening tool, especially for younger women, to facilitate decisions about which individuals to recommend for further diagnostic tests.

Macrophage migration inhibitory factor and DJ-1 in gastric cancer: differences between high-incidence and low-incidence areas

BACKGROUND

There is a need for sensitive and specific blood-borne markers for the detection of gastric cancer. Raised serum macrophage inhibitory factor (MIF) levels have been proposed as a marker for gastric cancer diagnosis but, to date, studies have only encompassed patients from high-incidence areas.

METHODS

We have compared the serum concentration of MIF in a large cohort of UK and Japanese gastric cancer patients, together with appropriate control subjects (age and gender matched). Carcinoembryonic antigen and H. pylori IgG were also measured, as was DJ-1, a novel candidate protein biomarker identified by analysis of gastric cancer cell line secretomes.

RESULTS

Marked elevations of the serum concentration of MIF and DJ-1 were seen in Japanese patients with gastric cancer compared with Japanese controls, a trend not seen in the UK cohort. These results could not be accounted for by differences in age, disease stage or H. pylori status.

CONCLUSION

In regions of high, but not low incidence of gastric cancer, both MIF and DJ-1 have elevated serum concentrations in gastric cancer patients, compared with controls. This suggests that differing mechanisms of disease pathogenesis may be at play in high- and low-incidence regions.