High levels of microRNA-21 in the stroma of colorectal cancers predict short disease-free survival in stage II colon cancer patients. Clin Exp Metastasis. 2011;28:27-38. [PMID: 21069438 PMCID: PMC2998639 DOI: 10.1007/s10585-010-9355-7]

Stromal miR-21 is more important than miR-21 of tumour cells for the progression of gastric cancer

BACKGROUND

Gastric cancer (GC) is a common cancer globally. miRNA-21 (miR-21) appears to be important in the tumourigenesis of almost all types of human cancer. However its precise localization in GC has yet to be clarified. We thus examined miR-21 localization in GC and revealed its clinicopathological importance.

METHODS

Tissue arrays of 469 GCs from 454 patients were examined for miR-21 using in situ hybridization (ISH). The positivity was evaluated separately in tumour cells and stromal cells. Conventional sections of 10 GCs were also stained. Eight cases were examined by quantitative RT-PCR (qRT-PCR).

RESULTS

miR-21 was highly expressed in tumour cells of 44% of cases and in cancer stroma of 51% of cases. miR-21 of tumour cells was not related to clinicopathological factors, whereas stromal miR-21 was related to many factors including tumour stage, size, and nodal metastasis. Stromal miR-21 gradually increased during tumour progression. ISH of whole sections showed stronger stromal positivity in invasive areas with desmoplastic reaction. Cancer stroma also showed higher miR-21 expression than tumour and non-tumourous tissue in the qRT-PCR study.

CONCLUSION

Stromal miR-21 is closely related to tumour progression in GC. Stromal miR-21 of tumours might be a target of treatment.

Elevated level of microRNA-21 in the serum of patients with colorectal cancer

In patients with colorectal cancer, circulating micro RNA-21 (miR-21) is overexpressed and may act as a potential diagnostic and prognostic biomarker. In the present study, serum miR-21 level was determined in patients with colorectal cancer and control subjects in an attempt to explore its potential clinical diagnostic and prognostic value. Serum levels of miR-21 were measured in 40 patients with colorectal adenocarcinoma and 40 control subjects using a quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) assay. Serum miR-21 levels were compared in the colorectal cancer patients and control subjects. Furthermore, the association between serum miR-21 level and the clinical stages of tumors was also examined in the patients. Serum miR-21 level was significantly elevated in colorectal adenocarcinoma patients relative to control subjects (P=0.0001), and it was revealed as a potential diagnostic biomarker for differentiating the patients from control subjects. Increased levels of serum miR-21 were associated with clinical stages of tumors in the patients (P=0.01). These results indicated that serum miR-21 levels could serve as a reliable diagnostic and prognostic biomarker for colorectal adenocarcinoma.

Diagnostic and prognostic value of microRNA-21 in colorectal cancer: an original study and individual participant data meta-analysis

BACKGROUND

We aimed to systematically summarize the diagnostic and prognostic value of circulating/tissue miR21 in patients with colorectal cancer.

METHODS

An original study was conducted to explore the potential value of circulating miR21 in colorectal cancer diagnosis and tissue miR21 in colorectal cancer prognosis. PUBMED and EMBASE were searched (to August, 2013) to identify eligible studies. To explore the diagnostic performance of circulating miR21, meta-analysis methods were used to pool sensitivity, specificity, positive and negative likelihood ratio, diagnostic OR and to construct a summary ROC curve. For prognostic meta-analysis, study-specific HRs of tissue miR21 for survival were summarized. Subgroup and sensitivity analyses were applied to explore heterogeneity.

RESULTS

Finally, 14 studies (including our study) were included in the meta-analyses. The pooled sensitivity, specificity, and AUC of circulating miR21 were 0.76 [95% confidence interval (CI), 0.59-0.88], 0.81 (95% CI, 0.76-0.85), and 0.81 (95% CI, 0.78-0.85) in diagnosing colorectal cancer. Patients with higher expression of tissue miR21 had significant inferior overall survival (OS; pooled HR, 1.56; 95% CI, 1.16-2.11) and disease-free survival (DFS; pooled HR, 1.35; 95% CI, 1.08-1.69). The individual participant data (IPD) meta-analysis demonstrated that tissue miR21 level was independently associated with worse colorectal cancer OS (HR, 1.69; 95% CI, 1.07-2.67; P = 0.023), whereas this association seems to be confined to males (P = 0.007) but not for females (P = 0.845).

CONCLUSIONS

Circulating miR21 level has potential value for colorectal cancer early detection, whereas high tissue miR21 level is associated with adverse colorectal cancer prognosis.

IMPACT

miR21 is a promising biomarker for early detection and prognosis of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 23(12); 2783-92. ©2014 AACR.

Tissue slide-based microRNA characterization of tumors: how detailed could diagnosis become for cancer medicine?

miRNAs are short, non-coding, regulatory RNAs that exert cell type-dependent, context-dependent, transcriptome-wide gene expression control under physiological and pathological conditions. Tissue slide-based assays provide qualitative (tumor compartment) and semi-quantitative (expression levels) information about altered miRNA expression at single-cell resolution in clinical tumor specimens. Reviewed here are key technological advances in the last 5 years that have led to implementation of fully automated, robust and reproducible tissue slide-based assays for in situ miRNA detection on US FDA-approved instruments; recent tissue slide-based discovery studies that suggest potential clinical applications of specific miRNAs in cancer medicine are highlighted; and the challenges in bringing tissue slide-based miRNA assays into the clinic are discussed, including clinical validation, biomarker performance, biomarker space and integration with other biomarkers.

miRNA expression in anaplastic thyroid carcinomas

Anaplastic thyroid carcinoma (ATC) is the most lethal form of thyroid neoplasia and represents an end stage of thyroid tumor progression. No effective treatment exists so far. In this study, we analyzed the miRNA expression profiles of 11 ATC by microarrays and their relationship with the mRNA expression profiles of the same 11 ATC samples. ATC show distinct miRNA expression profiles compared to other less aggressive thyroid tumor types. ATC show 18 commonly deregulated miRNA compared to normal thyroid tissue (17 downregulated and 1 upregulated miRNA). First, the analysis of a combined approach of the mRNA gene expression and of the bioinformatically predicted mRNA targets of the deregulated miRNA suggested a role for these regulations in the epithelial to mesenchymal transition (EMT) process in ATC. Second, the direct interaction between one of the upregulated mRNA target, the LOX gene which is an EMT key player, and a downregulated miRNA, the miR-29a, was experimentally validated by a luciferase assay in HEK cell. Third, we confirmed that the ATC tissue is composed of about 50% of tumor associated macrophages (TAM) and suggested, by taking into account our data and published data, their most likely direct or paracrine intercommunication between them and the thyroid tumor cells, amplifying the tumor aggressiveness. Finally, we demonstrated by in situ hybridization a specific thyrocyte localization of 3 of the deregulated miRNA: let-7g, miR-29a and miR-30e and we pointed out the importance of identifying the cell type localization before drawing any conclusion on the physiopathological role of a given gene.

Epidermal growth factor-like domain 7 predicts response to first-line chemotherapy and bevacizumab in patients with metastatic colorectal cancer

The number of approved antiangiogenic drugs is constantly growing and emphasizes the need for predictive biomarkers. The aim of this study was to analyze the predictive value of epidermal growth factor-like domain 7 (EGFL7) and microRNA-126 (miR126) to first-line chemotherapy combined with bevacizumab, in patients with metastatic colorectal cancer (mCRC). A total of 158 patients from two different, but comparable, cohorts were included. Analyses were performed on tumor tissue from the primary tumor either based on a whole-tumor resection or an endoscopic biopsy. EGFL7 was analyzed by immunohistochemistry (IHC) and miR126 by in situ hybridization (ISH). Both biomarkers were quantified by image-guided analyses. Endpoints were response rate (RR) and progression-free survival (PFS). The EGFL7 vessel area (VA) in tumor resections was closely related to treatment response with a median EGFL7 VA in responding patients of 4 [95% confidence interval (CI), 4-6] compared with 8.5 (95% CI, 7-11) in nonresponders, P = 0.0008. This difference translated into a borderline significant difference in PFS (P = 0.06). Furthermore, a significant relationship between high EGFL7 VA and KRAS mutation was detected (P = 0.049). The results showed no significant relationship between the miR126 VA and the clinical endpoints. Our study suggests a predictive value of EGFL7 in regard to first-line chemotherapy and bevacizumab in patients with mCRC and supports the mechanism of a dual blocking of the vascular endothelial growth factor-A and EGFL7 axis in this setting.

Stromal microRNA-21 levels predict response to 5-fluorouracil in patients with pancreatic cancer

BACKGROUND AND OBJECTIVES

MicroRNA-21 (miR-21) is upregulated and inversely associated with survival in many cancer types, including pancreatic ductal adenocarcinoma (PDAC). We studied the predictive value of miR-21 levels for gemcitabine or 5-fluorouracil (5-FU) response in tumor cells (TCs) or cancer associated fibroblasts (CAFs) in a cohort of PDAC patients from the RTOG 9704 trial.

METHODS

MiR-21 expression in CAFs and TCs, determined by in situ hybridization, of the 229 PDAC subset from RTOG 9704 was correlated with (i) histopathology characteristics using a chi-square test; and (ii) patient overall survival (OS) using the Cox proportional hazards model.

RESULTS

MiR-21 was strongly expressed in TCs and CAFs in 137/182 (75%) and 152/181 (84%) PDACs, respectively. MiR-21 expression in CAFs for the group given 5-FU for OS: (i) approached significance in a univariate analysis (hazard ratio [HR], 1.57; 95% confidence interval [CI], 0.95-2.57; P = 0.07); and (ii) was significant in the multivariate model (HR, 1.70; 95% CI, 1.03-2.82; P = 0.038).

CONCLUSIONS

MiR-21 expression in CAFs was associated with decreased OS in PDAC patients who received 5-FU, but not gemcitabine. These findings begin to identify stromal miR-21 as a marker to guide chemotherapy choice in PDAC patients.

miR-21 Expression in Cancer Cells may Not Predict Resistance to Adjuvant Trastuzumab in Primary Breast Cancer

Trastuzumab is established as standard care for patients with HER2-positive breast cancer both in the adjuvant and metastatic setting. However, 50% of the patients do not respond to the trastuzumab therapy, and therefore new predictive biomarkers are highly warranted. MicroRNAs (miRs) constitute a new group of biomarkers and their cellular expression can be determined in tumor samples by in situ hybridization (ISH) analysis. miR-21 is highly prevalent and up-regulated in breast cancer and has been linked to drug resistance in clinical and in vitro settings. To determine expression patterns of miR-21 in high-grade breast cancers, we examined miR-21 expression in 22 HER2-positive tumors and 15 HER2-negative high-grade tumors by ISH. The histological examination indicated that patient samples could be divided into three major expression patterns: miR-21 predominantly in tumor stroma, predominantly in cancer cells, or in both stromal and cancer cells. There was no obvious difference between the HER2-positive and HER2-negative tumors in terms of the miR-21 expression patterns and intensities. To explore the possibility that miR-21 expression levels and/or cellular localization could predict resistance to adjuvant trastuzumab in HER2-positive breast cancer patients, we analyzed additional 16 HER2-positive tumors from patients who were treated with trastuzumab in the adjuvant setting. Eight of the 16 patients showed clinical recurrence and were considered resistant. Examination of the miR-21 expression patterns and intensities revealed no association between the miR-21 scores in the cancer cell population (p = 0.69) or the stromal cells population (p = 0.13) and recurrent disease after adjuvant trastuzumab. Thus, our findings show that elevated miR-21 expression does not predict resistance to adjuvant trastuzumab.

MicroRNA-21 identified as predictor of cancer outcome: a meta-analysis

BACKGROUND

Growing evidence from recent studies has revealed the association of microRNA-21 (mir-21) with outcomes in multiple cancers, but inconsistent findings have been reported, which rationalized a summary and analysis of available data to investigate the prognostic role of mir-21.

MATERIALS AND METHODS

Eligible studies were identified through several search strategies and assessed for quality. Data was extracted from studies in terms of baseline characteristics and key statistics such as hazard ratio (HR), 95% confidence interval (CI) and P value, which were utilized to calculate pooled effect size.

RESULTS

25 studies were included in the meta-analysis to evaluate the prognostic role of mir-21 in malignant tumors. Elevated mir-21 level was demonstrated to moderately predict poor overall survival (OS) (HR = 1.903, 95% CI: 1.713-2.113, P = 0.000) and disease-free survival (DFS) (HR = 1.574, 95% CI: 1.139-2.175, P = 0.006) by the fixed and random effect model respectively. Importantly, subgroup analysis disclosed significant association between increased mir-21 level in cancerous tissue and worse survival status. Furthermore, over-expression of mir-21 was an independent prognostic factor for non-small cell lung cancer (NSCLC) and pancreatic cancer patients, with the pooled HR being 2.153 (95% CI: 1.693-2.739, P = 0.000) and 1.976 (95% CI: 1.639-2.384, P = 0.000).

CONCLUSIONS

Over-expression of mir-21, especially in cancerous tissue, was effectively predictive of worse prognosis in various carcinomas. Non-invasive circulating mir-21, however, exhibited modest ability to discriminate outcomes. Major concerns about mir-21 assay standardization and selection of specimen need to be fully addressed before its practical implementation in management of cancer.

Redefining high-risk patients with stage II colon cancer by risk index and microRNA-21: results from a population-based cohort

Background:

The aim of the present study was to analyse the prognostic value of microRNA-21 (miRNA-21) in patients with stage II colon cancer aiming at a risk index for this group of patients.

Methods:

A population-based cohort of 554 patients was included. MicroRNA-21 was analysed by qPCR based on tumour tissue. An index was created using the coefficients obtained from a collective multiple Cox regression. The entire procedure was cross-validated (10-fold). The performance of the index was quantified by time-dependent receiver operating characteristics curves.

Results:

High miRNA-21 expression was associated with an unfavourable recurrence-free cancer-specific survival (RF-CSS), hazard ratio 1.35 (95% confidence interval, 1.03–1.76) (P=0.028). The generated RF-CSS index divided the traditional high-risk patients into subgroups with 5-year RF-CSS rates of 87% and 73%, respectively (P<0.001). The overall survival (OS) index identified three different subgroups (P<0.001). Cross-validated 5-year OS rates were 88%, 68%, and 50%, respectively.

Conclusions:

This population-based study supports miRNA-21 as an additional prognostic biomarker in patients with stage II colon cancer. Furthermore, the introduction of a risk index may guide the use of postoperative adjuvant treatment in a more appropriate way compared with current practice.

Prognostic value of miR-21 in various cancers: an updating meta-analysis

BACKGROUND

Recently, more and more studies investigated the value of microRNA (miRNA) as a diagnostic or prognostic biomarker in various cancers. MiR-21 was found dysregulated in almost all types of cancers. While the prognostic role of miR-21 in many cancers has been studied, the results were not consistent.

METHODS

We performed a meta-analysis to investigate the correlation between miR-21 and survival of general cancers by calculating pooled hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

The pooled results of 63 published studies showed that elevated miR-21 was a predictor for poor survival of general carcinomas, with pooled HR of 1.91 (95%CI: 1.66-2.19) for OS, 1.42 (95% CI: 1.16-1.74) for DFS and 2.2 (95% CI: 1.64-2.96) for RFS/CSS. MiR-21 was also a prognostic biomarker in the patients who received adjuvant therapy, with pooled HR of 2.4 (95%CI: 1.18-4.9) for OS.

CONCLUSIONS

Our results showed that miR-21 could act as a significant biomarker in the prognosis of various cancers. Further studies are warranted before the application of the useful biomarker in the clinical.

DUF1220 protein domains drive proliferation in human neural stem cells and are associated with increased cortical volume in anthropoid primates

Genome sequences encoding DUF1220 protein domains show a burst in copy number among anthropoid species and especially humans, where they have undergone the greatest human lineage-specific copy number expansion of any protein coding sequence in the genome. While DUF1220 copy number shows a dosage-related association with brain size in both normal populations and in 1q21.1-associated microcephaly and macrocephaly, a function for these domains has not yet been described. Here we provide multiple lines of evidence supporting the view that DUF1220 domains function as drivers of neural stem cell proliferation among anthropoid species including humans. First, we show that brain MRI data from 131 individuals across 7 anthropoid species shows a strong correlation between DUF1220 copy number and multiple brain size-related measures. Using in situ hybridization analyses of human fetal brain, we also show that DUF1220 domains are expressed in the ventricular zone and primarily during human cortical neurogenesis, and are therefore expressed at the right time and place to be affecting cortical brain development. Finally, we demonstrate that in vitro expression of DUF1220 sequences in neural stem cells strongly promotes proliferation. Taken together, these data provide the strongest evidence so far reported implicating DUF1220 dosage in anthropoid and human brain expansion through mechanisms involving increasing neural stem cell proliferation.

Tracking endogenous amelogenin and ameloblastin in vivo

Research on enamel matrix proteins (EMPs) is centered on understanding their role in enamel biomineralization and their bioactivity for tissue engineering. While therapeutic application of EMPs has been widely documented, their expression and biological function in non-enamel tissues is unclear. Our first aim was to screen for amelogenin (AMELX) and ameloblastin (AMBN) gene expression in mandibular bones and soft tissues isolated from adult mice (15 weeks old). Using RT-PCR, we showed mRNA expression of AMELX and AMBN in mandibular alveolar and basal bones and, at low levels, in several soft tissues; eyes and ovaries were RNA-positive for AMELX and eyes, tongues and testicles for AMBN. Moreover, in mandibular tissues AMELX and AMBN mRNA levels varied according to two parameters: 1) ontogenic stage (decreasing with age), and 2) tissue-type (e.g. higher level in dental epithelial cells and alveolar bone when compared to basal bone and dental mesenchymal cells in 1 week old mice). In situ hybridization and immunohistodetection were performed in mandibular tissues using AMELX KO mice as controls. We identified AMELX-producing (RNA-positive) cells lining the adjacent alveolar bone and AMBN and AMELX proteins in the microenvironment surrounding EMPs-producing cells. Western blotting of proteins extracted by non-dissociative means revealed that AMELX and AMBN are not exclusive to mineralized matrix; they are present to some degree in a solubilized state in mandibular bone and presumably have some capacity to diffuse. Our data support the notion that AMELX and AMBN may function as growth factor-like molecules solubilized in the aqueous microenvironment. In jaws, they might play some role in bone physiology through autocrine/paracrine pathways, particularly during development and stress-induced remodeling.

MiR-21 expression in the tumor stroma of oral squamous cell carcinoma: an independent biomarker of disease free survival

Oral squamous cell carcinoma (OSCC) patients have a high mortality rate; thus, new clinical biomarkers and therapeutic options are needed. MicroRNAs (miRNAs) are short noncoding RNAs that regulate posttranscriptional gene expression and are commonly deregulated in OSCC and other cancers. MicroRNA-21 (miR-21) is the most consistently overexpressed miRNA in several types of cancer, and it might be a useful clinical biomarker and therapeutic target. To better understand the role of miR-21 in OSCC, paraffin-embedded tumor tissue samples from 86 patients with primary OSCC were analyzed by in situ hybridization. We found that miR-21 was primarily expressed in the tumor stroma and in some tumor-associated blood vessels with no expression in the adjacent normal epithelia or stroma. Using image analysis, we quantitatively estimated miR-21 expression levels specifically in the stroma of a cohort of OSCC samples. These miR-21 levels significantly correlated with disease free survival with the highest levels being located in the stroma. Stromal miR-21 expression was independently associated with a poorer prognosis, even after adjusting for clinical parameters (perineural invasion and N-stage) in a multivariate analysis. In summary, we have shown that miR-21 is located in the carcinoma cells, stroma and blood vessels of tumors, and its expression specifically in the stromal compartment has a negative prognostic value in OSCC.

Loss of microRNA-200a expression correlates with tumor progression in breast cancer

MicroRNAs (miRNAs) are 19∼22 nucleotide-long, noncoding, small RNAs, involved in post-transcriptional regulation of many target genes. The miRNA-200 family has been shown to play a crucial role in the epithelial to mesenchymal transition in human cancers. In situ hybridization (ISH) was used to investigate the expression level of miRNA-200a in breast cancers. Formalin-fixed, paraffin embedded (FFPE) tissues from normal breast, ductal carcinoma in situ (DCIS), primary cancers, and metastatic lymph nodes were achieved and constructed to tissue microarrays. MiRNA-200a expression was demonstrated in 95.2% of normal breast tissue samples and 80.4% of DCIS, whereas 178 (58.0%) of 307 breast cancers and 83.3% of metastatic lymph node samples lacked miRNA-200a expression (P < 0.001). Moreover, loss of MiRNA-200a expression correlated with high histologic grade (P = 0.017) and perinodal tumor extension (P = 0.026). However, miRNA-200a expression did not predict tumor recurrence or patient survival. In conclusion, loss of miRNA-200a is frequently observed in breast cancers, especially tumors with high grade histology. These findings suggest that miRNA-200a may play an important role in breast cancer initiation and progression. ISH can be used to detect miRNAs in FFPE sections, and should permit the validation of miRNAs as biomarkers in large clinical samples.

High tumor cell expression of microRNA-21 in node positive non-small cell lung cancer predicts a favorable clinical outcome

BACKGROUND

MicroRNA (miR)-21 has been revealed as an oncogene in cancer development, and is one of the miRNAs closely connected to angiogenesis. We aimed to explore the impact of miR-21 expression in both tumor and stromal compartments of non-small cell lung cancer (NSCLC), and correlations between miR-21 and angiogenic protein markers.

METHODS

From 335 unselected stage I to IIIA NSCLC carcinomas, duplicate tumor and tumor-associated stromal cores were collected in tissue microarrays (TMAs). In situ hybridization (ISH) was used to detect the expression of miR-21 separately in tumor cells and stromal cells of the tumor, and immunohistochemistry (IHC) was used to detect the expression of the protein markers protein kinase B (Akt), phosphatidylinositol-3-kinase (PI3K), hypoxia induced factor 1 (HIF1α) and vascular endothelial growth factor-A (VEGF-A).

RESULTS

In univariate analyses, high tumor cell expression of miR-21 in patients with lymph node metastasis was a positive prognostic factor (P = 0.024). High stromal miR-21 expression had a negative prognostic impact (P = 0.022). In the multivariate analysis, low tumor mir-21 expression in node positive patients was an independent adverse prognostic factor (HR 2.03, CI 95% 1.09-3.78, P = 0.027).

CONCLUSIONS

In patients with lymph node metastasis, miR-21 expression in tumor cells is an independent positive prognostic factor. High stromal miR-21 expression is a negative prognostic factor.

MiR-141 suppresses the migration and invasion of HCC cells by targeting Tiam1

Background

We have demonstrated that T lymphoma invasion and metastasis 1 (Tiam1) gene is associated with the poor prognosis of patients with hepatocellular carcinoma (HCC), and we used a computational approach to identify miR-141 as a Tiam1-targeting microRNA (miRNA). Here, we explored the function of miR-141 and the relationship between miR-141 and Tiam1 gene in HCC.

Methods

The miR-141 expression in HCC tissues and cell lines was detected and its roles in regulation of HCC cell proliferation, migration and invasion and target gene expression was investigated. Tiam1 was identified as a novel target of miR-141. Ethics statement: our study was approved by the Nanfang Hospital Medical Ethics Committee Ethics statement. Written informed consent was obtained before collection.

Results

Based on in situ hybridization (ISH) analysis, miR-141 was down-regulated in the same HCC samples. Kaplan-Meier analysis demonstrated that patients with low miR-141 expression had poorer overall survival rate than that of the patients with high miR-141 expression. Furthermore, multivariate Cox regression analysis indicated that miR-141 could serve as an independent prognostic factor in HCC. MiR-141 significantly inhibited in vitro cell proliferation, migration and invasion as proved by gain- and loss- of function studies, while the mRNA and protein levels of Tiam1 were reduced in cells over-expressing miR-141. Moreover, Tiam1 treatment antagonized this effect, while knockdown of Tiam1 by Tiam1 short hairpin RNA (shTiam1) induced inhibitory effects.

Conclusions

These findings indicated that miR-141 functions as a tumor suppressor and inhibits the migration and invasion of HCC cells by targeting Tiam1, which may provide novel prognostic and treatment strategies for HCC patients.

MicroRNAs (miRNAs) as biomarker(s) for prognosis and diagnosis of gastrointestinal (GI) cancers

Gastrointestinal (GI) cancers remain one of the most common malignancies and are the second common cause of cancer deaths worldwide. The limited effectiveness of therapy for patients with advanced stage and recurrent disease is a reflection of an incomplete understanding of the molecular basis of GI carcinogenesis. Major advancements have improved our understanding of pathology and pathogenesis of GI cancers, but high mortality rates, unfavorable prognosis and lack of clinical predictive biomarkers provide an impetus to investigate new sensitive and specific diagnostic and prognostic markers for GI cancers. MicroRNAs (miRNAs) are short (19-24 nucleotides) noncoding RNA molecules that regulate gene expression at the posttranscriptional level thus playing an important role in modulating various biological processes including, but not limited to developmental processes, proliferation, apoptosis, metabolism, differentiation, epithelial-mechenchymal transition and are involved in the initiation and progression of various human cancers. Unique miRNA expression profiles have been observed in various cancer types at different stages, suggesting their potential as diagnostic and prognostic biomarkers. Due to their tumor-specific and tissue-specific expression profiles, stability, robust clinical assays for detection in serum as well as in formalin-fixed tissue samples, miRNAs have emerged as attractive candidates for diagnostic and prognostic applications. This review summarizes recent research supporting the utility of miRNAs as novel diagnostic and prognostic tools for GI cancers.

The anti-miR21 antagomir, a therapeutic tool for colorectal cancer, has a potential synergistic effect by perturbing an angiogenesis-associated miR30

Colon cancer has the third highest incidence and mortality among cancers in the United States. MicroRNA-21 (miR21) has been described as an oncomir that is highly overexpressed in tumor tissue from colorectal cancer. Recent studies showed that silencing of miR21 through use of a miR21 inhibitor (anti-miR21) affected viability, apoptosis and the cell cycle in colon cancer cells. We identified an anti-miR21 that targets miR21 to inhibit genes by both post-transcriptional gene silencing and transcriptional gene silencing in the cytoplasm and nucleus, respectively. Overexpression of anti-miR21 in colon cancer cells caused changes in miRNA expression levels. We found that treatment with anti-miR21 down-regulated expression of miR30, which is involved in angiogenesis. In an in vitro angiogenesis assay, network formation induced by an angiogenesis activator was reduced upon treatment with anti-miR21. Sequence analysis of anti-miR21 and pri-miR30 revealed homology between anti-miR21 and the 3′ end of pri-miR30, suggesting that anti-miR21 may bind to pri-miR30 and block processing of the miRNA processing. These results suggest anti-miR21 has a role not only in tumor growth but also in angiogenesis. Therefore, treatment with the anti-miR21 antagomir may have a synergistic effect mediated through suppression of miR30.

Use of microRNAs in personalized medicine

Personalized medicine comprises the genetic information together with the phenotypic and environmental factors to yield healthcare tailored to an individual and removes the limitations of the "one-size-fits-all" therapy approach. This provides the opportunity to translate therapies from bench to clinic, to diagnose and predict disease, and to improve patient-tailored treatments based on the unique signatures of a patient's disease and further to identify novel treatment schedules. Nowadays, tiny noncoding RNAs, called microRNAs, have captured the spotlight in molecular biology with highlights like their involvement in DNA translational control, their impression on mRNA and protein expression levels, and their ability to reprogram molecular signaling pathways in cancer. Realizing their pivotal roles in drug resistance, they emerged as diagnostic targets orchestrating drug response in individualized therapy examples. It is not premature to think that researchers could have the US Food and Drug Administration (FDA)-approved kit-based assays for miRNA analysis in the near future. We think that miRNAs are ready for prime time.

Prognostic role of microRNA-21 in colorectal cancer: a meta-analysis

BACKGROUND

To date, many studies have shown that microRNAs (miRNA) exhibit altered expression in various cancers and may play an important role as prognostic biomarker of cancers. The present meta-analysis summarizes the recent advances in the use of microRNA-21 (miR-21) in the assessment of colorectal cancer and analyzes the prognostic role of miR-21 for survival outcome.

METHODOLOGY/PRINCIPAL FINDINGS

The present meta-analysis was performed by searching PubMed through multiple search strategies. Data were extracted from studies comparing overall survival (OS) in patients with colorectal cancer who showed higher expression of miR-21 than similar patients. Pooled hazard ratios (HRs) of miR-21 for survival and 95% confidence intervals (CI) were calculated. Seven studies with a total of 1174 patients were included this meta-analysis. For overall survival (OS), the pooled hazard ratio (HR) of higher miR-21 expression in colorectal cancer was 1.76 (95% CI: 1.34-2.32, P=0.000). After elimination of heterogeneity, the pooled HR was 2.32 (95% CI: 1.82-2.97, P=0.000), which was found to significantly predict poorer survival. The subgroup analysis suggested that elevated miR-21 level and patients' survival correlated with III/IV stage (HR=5.35, 95% CI: 3.73-7.66).

CONCLUSIONS/SIGNIFICANCE

The present findings suggest that high expression of miR-21 might predict poor prognosis in patients with colorectal cancer.

High miR-21 expression from FFPE tissues is associated with poor survival and response to adjuvant chemotherapy in colon cancer

Colon cancer (CC) is a leading cause of cancer mortality. Novel biomarkers are needed to identify CC patients at high risk of recurrence and those who may benefit from therapeutic intervention. The aim of this study is to investigate if miR-21 expression from RNA isolated from formalin-fixed paraffin-embedded (FFPE) tissue sections is associated with prognosis and therapeutic outcome for patients with CC. The expression of miR-21 was measured by quantitative reverse transcriptase-polymerase chain reaction in a Japanese cohort (stage I-IV, n = 156) and a German cohort (stage II, n = 145). High miR-21 expression in tumors was associated with poor survival in both the stage II/III Japanese (p = 0.0008) and stage II German (p = 0.047) cohorts. These associations were independent of other clinical covariates in multivariable models. Receipt of adjuvant chemotherapy was not beneficial in patients with high miR-21 in either cohort. In the Japanese cohort, high miR-21 expression was significantly associated with poor therapeutic outcome (p = 0.0001) and adjuvant therapy was associated with improved survival in patients with low miR-21 (p = 0.001). These results suggest that miR-21 is a promising biomarker to identify patients with poor prognosis and can be accurately measured in FFPE tissues. The expression of miR-21 may also identify patients who will benefit from adjuvant chemotherapy.

The prognostic significance of APC gene mutation and miR-21 expression in advanced-stage colorectal cancer

AIM

Colorectal cancer (CRC) is the second commonest cause of cancer death in Taiwan. Although numerous genes have been associated with tumorigenesis in colorectal cancer, only a few have been validated and used as biomarkers for predicting clinical outcome. The aim of this study was to analyse the association of APC gene mutation and miR-21 expression with clinical outcome in CRC patients.

METHOD

In total, 195 colorectal cancer patients were enrolled in a single medical centre between 2003 and 2007. APC gene mutation and expression of APC and miR-21 were analysed by direct DNA sequencing and real-time reverse transcription polymerase chain reaction. The primary outcome included 5-year overall survival and univariate (Kaplan-Meier) and multivariate (Cox regression) analyses of prognostic factors.

RESULTS

The results showed that 66 (33.8%) of 195 tumour tissues contained an APC mutation. The predominant APC gene variations were deletion mutations (50.0%). APC gene expression was low in CRC and negatively correlated with miR-21 expression and gene mutation. In advanced-stage cancer, patients with APC mutation/high miR-21 had poorer overall survival rates than those with APC mutation/low miR-21, APC wild-type/high miR-21 and APC wild-type/low miR-21.

CONCLUSION

In Taiwan, downregulation of the APC gene in CRC correlated with gene mutation and miR-21 upregulation. APC mutation and miR-21 expression could be used to predict the clinical outcome of CRC, especially in patients with advanced disease.

Epigenetic regulation of miR-21 in colorectal cancer: ITGB4 as a novel miR-21 target and a three-gene network (miR-21-ITGΒ4-PDCD4) as predictor of metastatic tumor potential

Previous studies have uncovered several transcription factors that determine biological alterations in tumor cells to execute the invasion-metastasis cascade, including the epithelial-mesenchymal transition (EMT). We sought to investigate the role of miR-21 in colorectal cancer regulation. For this purpose, miR-21 expression was quantified in a panel of colorectal cancer cell lines and clinical specimens. High expression was found in cell lines with EMT properties and in the vast majority of human tumor specimens. We demonstrate in a cell-specific manner the occupancy of MIR-21 gene promoter by AP-1 and ETS1 transcription factors and, for the first time, the pattern of histone posttranslational modifications necessary for miR-21 overexpression. We also show that Integrin-β4 (ITGβ4), exclusively expressed in polarized epithelial cells, is a novel miR-21 target gene and plays a role in the regulation of EMT, since it is remarkably de-repressed after transient miR-21 silencing and downregulated after miR-21 overexpression. miR-21-dependent change of ITGβ4 expression significantly affects cell migration properties of colon cancer cells. Finally, in a subgroup of tumor specimens, ROC curve analysis performed on quantitative PCR data sets for miR-21, ITGβ4, and PDCD4 shows that the combination of high miR-21 with low ITGβ4 and PDCD4 expression is able to predict presence of metastasis. In conclusion, miR-21 is a key player in oncogenic EMT, its overexpression is controlled by the cooperation of genetic and epigenetic alterations, and its levels, along with ITGβ4 and PDCD4 expression, could be exploited as a prognostic tool for CRC metastasis.

miRNAs as colorectal cancer biomarkers: current progress and future challenges

SUMMARY Colorectal cancer is a common pathology, accounting for approximately 8% of cancer deaths. The induction of a metastatic cascade heralds a potentially devastating end point with limited curative therapeutic options and early detection is, therefore, crucial. Novel diagnostic and predictive biomarkers are urgently required as current candidates lack sensitivity and specificity, particularly in the context of early disease. miRNAs are a group of short noncoding RNAs which regulate gene expression at a post-transcriptional level and have recently been shown to hold promise as fecal, circulating or tissue biomarkers. This review explores current progress and future challenges in this rapidly expanding field.

MicroRNA-21 as a potential colon and rectal cancer biomarker

Colorectal cancer (CRC) is one of the most common malignant diseases worldwide and the prognosis is still poor although much progress has been achieved in recent years. In order to reduce CRC-related deaths, many studies are aimed at identifying novel screening- and prognosis-related biomarkers. MicroRNAs (miRNAs) are a class of 18-27-nucleotide single-stranded RNA molecules that regulate gene expression at the post-transcriptional level. It has been demonstrated that miRNAs regulate a variety of physiological functions, including development, cell differentiation, proliferation, and apoptosis. They play important roles in various physiologic and developmental processes and in the initiation and progression of various human cancers. It has been shown that miRNAs can critically regulate tumor cell gene expression, and evidence suggests that they may function as both oncogenes and tumor suppressor genes. In CRC, miRNAs-21 is one of the most important miRNAs and is rapidly emerging as a novel biomarker in CRC, with good potential as a diagnostic and therapeutic target. In this review, we summarize the latest research findings of the clinicopathological relevance of miRNAs-21 in CRC initiation, development, and progress, highlighting its potential diagnostic, prognostic, and therapeutic application, as well as discussing future prospects.

Expression, tissue distribution and function of miR-21 in esophageal squamous cell carcinoma

Objective

MiR-21 is an oncomir expressed by malignant cells and/or tumor microenvironment components. In this study we focused on understanding the effects of stromal miR-21 on esophageal malignant cells.

Design

MiR-21 expression was evaluated in formalin-fixed paraffin-embedded samples from patients with esophageal squamous-cell carcinoma (SCC) by quantitative RT-PCR. MiR-21 tissue distribution was visualized with in situ hybridization. A co-culture system of normal fibroblasts and esophageal cancer cells was used to determine the effects of fibroblasts on miR-21 expression levels, and on SCC cell migration and invasion.

Results

MiR-21 was overexpressed in SCCs, when compared to the adjacent non-tumor tissues (P = 0.0007), and was mainly localized in the cytoplasm of stromal cells adjacent to malignant cells. Accordingly, miR-21 expression was increased in tumors with high versus low stromal content (P = 0.04). When co-cultured with normal fibroblasts, miR-21 expression was elevated in SCC cells (KYSE-30), while its expression was restricted to fibroblasts when co-cultured with adenocarcinoma cells (OE-33 and FLO-1). MiR-21 was detected in conditioned media of cancer cell lines, illustrating the release of this miRNA into the environment. Co-culturing with normal fibroblasts or addition of fibroblast conditioned media caused a significant increase in cell migration and invasion potency of KYSE-30 cells (P<0.0001). In addition, co-culturing cancer cells with fibroblasts and expression of miR-21 induced the expression of the cancer associated fibroblast (CAF) marker S100A4.

Conclusions

MiR-21 expression is mostly confined to the SCC stroma and its release from fibroblasts influences the migration and invasion capacity of SCC cells. Moreover, miR-21 may be an important factor in “activating” fibroblasts to CAFs. These findings provide new insights into the role of CAFs and the extracellular matrix in tumor microenvironment formation and in tumor cell maintenance, and suggest miR-21 may contribute to cellular crosstalk in the tumor microenvironment.

Expression of miR-155 and miR-126 in situ in cutaneous T-cell lymphoma

Recently, miR-155 has been implicated in cutaneous T-cell lymphoma (CTCL). Thus, elevated levels of miR-155 were observed in skin lesions from CTCL patients as judged from qPCR and micro-array analysis and aberrant, high miR-155 expression was associated with severe disease. Moreover, miR-155 promoted proliferation of malignant T cells in vitro. Little is, however, known about which cell types express miR-155 in vivo in CTCL skin lesions. Here, we study miR-155 expression using in situ hybridization (ISH) with a miR-155 probe, a negative control (scrambled), and a miR-126 probe as a positive control in nine patients with mycosis fungoides, the most frequent subtype of CTCL. We provide evidence that both malignant and non-malignant T cells stain weakly to moderately positive with the miR-155 probe, but generally negative with the miR-126 and negative control probes. Reversely, endothelial cells stain positive for miR-126 and negative for miR-155 and the control probe. Solitary T cells with a malignant morphology display brighter staining with the miR-155 probe. Taken together, our findings suggest that both malignant and non-malignant T cells express miR-155 in situ in CTCL. Moreover, they indicate heterogeneity in miR-155 expression among malignant T cells.

MicroRNA-21 in pancreatic ductal adenocarcinoma tumor-associated fibroblasts promotes metastasis

INTRODUCTION

Pancreatic ductal adenocarcinoma (PDAC) is projected to rise to the second leading cause of U.S. cancer-related deaths by 2020. Novel therapeutic targets are desperately needed. MicroRNAs (miRs) are small noncoding RNAs that function by suppressing gene expression and are dysregulated in cancer. miR-21 is overexpressed in PDAC tumor cells (TC) and is associated with decreased survival, chemoresistance and invasion. Dysregulation of miR regulatory networks in PDAC tumor-associated fibroblasts (TAFs) have not been previously described. In this study, we show that miR-21 expression in TAFs promotes TC invasion.

METHODS

In-situ hybridization for miR-21 was performed on the 153 PDAC patient UCLA tissue microarray and 23 patient-matched lymph node metastases. Stromal and TC histoscores were correlated with clinicopathologic parameters by univariate and multivariate Cox regression. miR-21 positive cells were further characterized by immunofluorescence for mesenchymal/epithelial markers. For in vitro studies, TAFs were isolated from freshly resected human PDAC tumors by the outgrowth method. miR-21 was overexpressed/inhibited in fibroblasts and then co-cultured with GFP-MiaPaCa TCs to assess TC invasion in modified Boyden chambers.

RESULTS

miR-21 was upregulated in TAFs of 78% of tumors, and high miR-21 significantly correlated with decreased overall survival (P = 0.04). Stromal miR-21 expression was also significantly associated with lymph node invasion (P = 0.004), suggesting that it is driving TC spread. Co-immunofluorescence revealed that miR-21 colocalized with peritumoral fibroblasts expressing α-smooth muscle actin. Moreover, expression of miR-21 in primary TAFs correlated with miR-21 in TAFs from patient-matched LN metastases; evidence that PDAC tumor cells induce TAFs to express miR-21. miR-21 expression in TAFs and TCs promotes invasion of TCs and is inhibited with anti-miR-21.

CONCLUSIONS

miR-21 expression in PDAC TAFs is associated with decreased overall survival and promotes TC invasion. Anti-miR-21 may represent a novel therapeutic strategy for dual targeting of both tumor and stroma in PDAC.

Visualising and quantifying angiogenesis in metastatic colorectal cancer : A comparison of methods and their predictive value for chemotherapy response

PURPOSE

Angiogenesis plays an important role in tumour growth and dissemination. We have recently shown that blood vessel density, determined by image analysis based on microRNA-126 (miRNA-126) in situ hybridization (ISH) in the primary tumours of metastatic colorectal cancers (mCRC), is predictive of chemotherapy response. Here, we evaluated whether more general approaches to determine vessel density in primary tumours are equally predictive of chemotherapy response.

METHODS

This methodological study was carried out using paraffin embedded tissues from primary tumours of 89 patients with mCRC, who had all been treated with first-line chemotherapy (XELOX). Tissue sections from the deepest invasive tumour front were processed for miRNA-126 ISH and CD34 immunohistochemistry (IHC). Estimates of microvessel density (MVD) were obtained for both miRNA-126 and CD34 by quantitative image analyses (MVDi), vascular area per image (μm²) analyses, and manually counting vessels in vascular hot spots (MVDh). Clinical responses were evaluated according to Response Evaluation Criteria In Solid Tumours (RECIST).

RESULTS

The MVDi for miRNA-126 showed a significant correlation with treatment response (p=0.01), with a median value of 2,071 μm² (95% CI, 1,505-3,075 μm²) in the responder group compared to 1,337 μm² (95% CI, 1,038-1,499 μm²) in the non-responder group. This difference translated into a significant difference in progression free survival (p=0.01).

CONCLUSIONS

The methodological assessment of MVD and the molecular vessel marker are both important for the prediction of the chemotherapy response in mCRC. Our findings indicate that MVDi for miRNA-126 represents a powerful estimate and may serve as a clinical biomarker superior to MVDh.

miR-21 and its target gene CCL20 are both highly overexpressed in the microenvironment of colorectal tumors: significance of their regulation

Recently, we reported a functional interaction between miR-21 and its identified chemokine target CCL20 in colorectal cancer (CRC) cell lines. Here, we investigated whether such functional interactions are permitted at the cellular level which would require an inverse correlation of expression and also co-expression of miR-21 and CCL20 in the same cell. Expression profiling was performed using qPCR, and ELISA, in situ hybridization and immunohistochemistry were applied for the presentation of their cellular localization. We demonstrated that miR-21 as well as CCL20 were both significantly upregulated in CRC tissues; thus, showing no antidromic expression pattern. This provided an initial clue that miR-21 and CCL20 may not be expressed in the same cell. In addition, we located miR-21 expression at the cellular level predominantly in stromal cells such as tumor-associated fibroblasts and to a minor degree in immune cells such as macrophages and lymphocytes. Likewise, CCL20 expression was primarily detected in tumor-infiltrating immune cells. Thus, investigating the cellular localization of miR-21 and its target CCL20 revealed that both molecules are expressed predominantly in the microenvironment of CRC tumors.

Pleiotropic actions of miR-21 highlight the critical role of deregulated stromal microRNAs during colorectal cancer progression

The oncogene microRNA-21 (miRNA; miR-21) is overexpressed in most solid organ tumours; however, a recent examination of stage II colorectal cancer (CRC) specimens suggests this may be a stromal phenomenon and not only a feature of cancer cells. In vitro and in vivo studies show that miR-21 has potent pro-metastatic effects in various malignant carcinoma cell lines. The tumour microenvironment has also been identified as a key actor during the metastatic cascade; however to date the significance of deregulated miR-21 expression within the cancer-associated stroma has not been examined. In the present study, a quantitative RT-PCR-based analysis of laser microdissected tissue confirmed that miR-21 expression is associated with a four-fold mean increase in CRC stroma compared with normal tissue. In situ hybridisation using locked nucleic acid probes localised miR-21 expression predominantly to fibroblasts within tumour-associated stroma. To study the molecular and biological impact of deregulated stromal miR-21 in CRC, stable ectopic expression was induced in immortalised fibroblasts. This resulted in upregulated α-smooth muscle actin expression implying miR-21 overexpression is driving the fibroblast-to-myofibroblast transdifferentiation. Conditioned medium from miR-21-overexpressing fibroblasts protected CRC cells from oxaliplatin-induced apoptosis and increased their proliferative capacity. 3D organotypic co-cultures containing fibroblasts and CRC cells revealed that ectopic stromal miR-21 expression was associated with increased epithelial invasiveness. Reversion-inducing cysteine-rich protein with kazal motifs, an inhibitor of matrix-remodelling enzyme MMP2, was significantly downregulated by ectopic miR-21 in established and primary colorectal fibroblasts with a reciprocal rise in MMP2 activity. Inhibition of MMP2 abrogated the invasion-promoting effects of ectopic miR-21. This data, which characterises a novel pro-metastatic mechanism mediated by miR-21 in the CRC stroma, highlights the importance of miRNA deregulation within the tumour microenvironment and identifies a potential application for stromal miRNAs as biomarkers in cancer.

The prognostic value of microRNAs varies with patient race/ethnicity and stage of colorectal cancer

PURPOSE

MicroRNAs (miRNA) have potential prognostic value for colorectal cancers; however, their value based on patient race/ethnicity and pathologic stage has not been determined. The goal was to ascertain the prognostic value of 5 miRNAs with increased expression in colorectal cancers of African American (black) and non-Hispanic Caucasian (white) patients.

EXPERIMENTAL DESIGN

TaqMan quantitative real-time PCR was used to quantify expression of miR-20a, miR-21, miR-106a, miR-181b, and miR-203 in paired normal and tumor colorectal cancer archival tissues collected from 106 black and 239 white patients. The results were correlated with overall survival based on patient race/ethnicity and pathologic stage. Because decisions about adjuvant therapy are important for stage III colorectal cancers, and because miR-181b seemed to have prognostic value only for stage III black patients, we assessed its prognostic value in a separate cohort of 36 stage III colorectal cancers of blacks.

RESULTS

All 5 miRNAs had higher expression in colorectal cancers (>1.0-fold) than in corresponding normal tissues. High expression of miR-203 was associated with poor survival of whites with stage IV colorectal cancers (HR = 3.00; 95% CI, 1.29-7.53), but in blacks it was an indicator of poor survival of patients with stages I and II colorectal cancers (HR = 5.63; 95% CI, 1.03-30.64). Increased miR-21 expression correlated with poor prognosis for white stage IV patients (HR = 2.50; 95% CI, 1.07-5.83). In both test and validation cohorts, high miR-181b expression correlated with poor survival of only black patients with stage III colorectal cancers (HR = 1.94; 95% CI, 1.03-3.67).

CONCLUSION

These preliminary findings suggest that the prognostic value of miRNAs in colorectal cancers varies with patient race/ethnicity and stage of disease.

MicroRNA biomarkers in glioblastoma

Recent research suggests that deregulation of microRNAs (miRNAs) is involved in initiation and progression of many cancers, including gliomas and that miRNAs hold great potential as future diagnostic and therapeutic tools in cancer. MiRNAs are a class of short non-coding RNA sequences (18-24 nucleotides), which base-pair to target messenger RNA (mRNA) and thereby cause translational repression or mRNA degradation based on the level of complementarity between strands. Profiling miRNAs in clinical glioblastoma samples has shown aberrant expression of numerous miRNAs when compared to normal brain tissues. Understanding these alterations is key to developing new biomarkers and intelligent treatment strategies. This review presents an overview of current knowledge about miRNA alterations in glioblastoma while focusing on the clinical future of miRNAs as biomarkers and discussing the strengths and weaknesses of various methods used in evaluating their expression.

Hypoxia induces the overexpression of microRNA-21 in pancreatic cancer cells

BACKGROUND

Pancreatic cancer cells exist in a hypoxic microenvironment containing numerous factors that impact tumor survival, proliferation, and metastasis. MicroRNAs (miRs) are differentially expressed in cancer but also altered by hypoxia. We hypothesized that hypoxia could induce expression of miR-21, an oncomir in pancreatic cancer cells.

MATERIALS AND METHODS

We examined how hypoxia regulates miR-21 expression in pancreatic cancer cell lines (BxPC-3, AsPC-1) by stem-loop RT-PCR. Chromatin immunoprecipitation assays were used to study how hypoxia alters hypoxia-inducible factor (HIF)-1α binding to the hypoxia response element of miR-21. BxPC-3 and AsPC-1 cells were transfected with a constitutively stable HIF-1α subunit or vector control (pcDNA3.1) to determine the influence of miR-21 in normoxia. The effect of mature miR-21 sense and antisense oligonucleotides on proliferation and apoptosis in hypoxic and normoxic conditions was assessed via WST-1 assay and flow cytometry.

RESULTS

MiR-21 levels increased in all cell lines grown in hypoxic conditions versus normoxia, whereas siRNA targeting HIF-1α reduced miR-21 expression. Hypoxic conditions resulted in direct binding of HIF-1α to the predicted binding site in miR-21. Transfection with a constitutively stable HIF-1α expression plasmid in normoxia resulted in upregulated miR-21, similar to that seen in hypoxia. Cells transfected with antisense constructs targeting miR-21 had reduced proliferation and increased apoptosis in normoxia, whereas miR-21 overexpression abrogated hypoxia-associated reductions in proliferation.

CONCLUSIONS

MiR-21 is induced by hypoxia in pancreatic cancer cells via HIF-1α upregulation. MiR-21 overexpression allows cells to avoid apoptosis in a hypoxic microenvironment. Inhibition of miR-21 expression may increase cellular susceptibility to hypoxia in pancreatic cancer.

A review on the electrochemical biosensors for determination of microRNAs

MicroRNAs (miRNAs) are a family of non-protein-coding, endogenous, small RNAs. They are a group of gene regulators that function mainly by binding the 3' untranslated regions of specific target messenger RNA (mRNA) leading to gene inactivation by repression of mRNA transcription or induction of mRNA. Mature miRNAs are short molecules approximately 22 nucleotides in length. They regulate a wide range of biological functions from cell proliferation and death to cancer progression. Cellular miRNA expression levels can be used as biomarkers for the onset of disease states and in gene therapy for genetic disorders. Methods for detection of miRNA mainly include northern blotting, microarray, polymerase chain reaction (PCR). This review focuses on the use of electrochemical biosensors for the detection of microRNA.

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.

The prognostic importance of miR-21 in stage II colon cancer: a population-based study

BACKGROUND

Despite several years of research and attempts to develop prognostic models a considerable fraction of stage II colon cancer patients will experience relapse within few years from their operation. The aim of the present study was to investigate the prognostic importance of miRNA-21 (miR-21), quantified by in situ hybridisation, in a unique, large population-based cohort.

PATIENTS AND METHODS

The study included 764 patients diagnosed with stage II colon cancer in Denmark in the year 2003. One section from a representative paraffin-embedded tumour tissue specimen from each patient was processed for analysis of miR-21 and quantitatively assessed by image analysis.

RESULTS

The miR-21 signal was predominantly observed in fibroblast-like cells located in the stromal compartment of the tumours. We found that patients expressing high levels of miR-21 had significantly inferior recurrence-free cancer-specific survival (RF-CSS): HR=1.26; 95% CI: 1.15-1.60; P<0.001. In Cox regression analysis, a high level of miR-21 retained its prognostic importance and was found to be significantly related to poor RF-CSS: HR=1.41; 95% CI: 1.19-1.67; P<0.001.

CONCLUSION

The present study showed that increasing miR-21 expression levels were significantly correlated to decreasing RF-CSS. Further investigations of the clinical importance of miR-21 in the selection of high-risk stage II colon cancer patients are merited.

Protective effect of caffeine against high sugar-induced transcription of microRNAs and consequent gene silencing: a study using lenses of galactosemic mice

PURPOSE

Previous studies have shown that caffeine prevents the formation of cataracts induced by a high-galactose diet and consequent oxidative stress. The objective of this study was to investigate if this protective effect is reflected in the attenuation of the transcription of microRNAs (miRNAs) known to induce apoptosis and cell death by gene silencing.

METHODS

Young CD-1 mice were fed either a normal laboratory diet or a diet containing 25% galactose with or without 1% caffeine. One week later, the animals were euthanized, and the lenses isolated and promptly processed for RNA isolation and subsequent preparation of cDNAs by reverse transcriptase reaction. Mature miRNA (miR)-specific cDNAs were then quantified with PCR in a 96-well microRNA-specific cassette using an ABI7900HT PCR machine.

RESULTS

As expected from previous studies, the lenses were positive for all 84 miRs corresponding to the miRNA probes present in the cassette wells. However, the levels of at least 19 miRs were significantly elevated in galactosemic lenses compared to those in the normal lenses. The majority are proapoptotic. Such elevation was inhibited by caffeine. This has been demonstrated for the first time.

CONCLUSIONS

Since aberrant elevation of miRNAs silences various genes and consequently deactivates protein translation, and since caffeine downregulates such aberration, the beneficial effect of caffeine could be attributed to its ability to suppress elevation of toxic miRs and consequent gene silencing.

MiRNA-362-3p induces cell cycle arrest through targeting of E2F1, USF2 and PTPN1 and is associated with recurrence of colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer deaths in Western countries. A significant number of CRC patients undergoing curatively intended surgery subsequently develop recurrence and die from the disease. MicroRNAs (miRNAs) are aberrantly expressed in cancers and appear to have both diagnostic and prognostic significance. In this study, we identified novel miRNAs associated with recurrence of CRC, and their possible mechanism of action. TaqMan(®) Human MicroRNA Array Set v2.0 was used to profile the expression of 667 miRNAs in 14 normal colon mucosas and 46 microsatellite stable CRC tumors. Four miRNAs (miR-362-3p, miR-570, miR-148 a* and miR-944) were expressed at a higher level in tumors from patients with no recurrence (p<0.015), compared with tumors from patients with recurrence. A significant association with increased disease free survival was confirmed for miR-362-3p in a second independent cohort of 43 CRC patients, using single TaqMan(®) microRNA assays. In vitro functional analysis showed that over-expression of miR-362-3p in colon cancer cell lines reduced cell viability, and proliferation mainly due to cell cycle arrest. E2F1, USF2 and PTPN1 were identified as potential miR-362-3p targets by mRNA profiling of HCT116 cells over-expressing miR-362-3p. Subsequently, these genes were confirmed as direct targets by Luciferase reporter assays and their knockdown in vitro phenocopied the effects of miR-362-3p over-expression. We conclude that miR-362-3p may be a novel prognostic marker in CRC, and hypothesize that the positive effects of augmented miR-362-3p expression may in part be mediated through the targets E2F1, USF2 and PTPN1.

Prognostic role of microRNA-21 in non-small cell lung cancer: a meta-analysis

INTRODUCTION

Many studies have reported that microRNA-21 (miR-21) mihght predict the survival outcome in non-small cell lung cancers (NSCLCs) but the opposite opinion has also been expressed. The aim of this study was to summarize the evidence for a prognostic role of miR-21.

MATERIALS AND METHODS

All the eligible studies was searched by Medline and EMBASE and patients' clinical characteristics and survival outcome were extracted. Then a meta-analysis was performed to clarify the prognostic role of the miR-21 expression in different subgroups.

RESULTS

A total of 8 eligible articles were yielded covering survival outcomes or clinical characteristics. The combined hazard ratio (HR) and 95% confidence interval (95% CI) for overall survival (OS) was 2.19 [0.76, 6.30], while the combined HR (95% CI) of Asian group for OS had a significant result, 5.49 [2.46, 12.27]. The combined HR (95% CI) for recurrence free survival or disease free survival (RFS/DFS) was 2.31 [1.52, 3.49]. Odds ratios (ORs) showed that the miR-21 expression was associated with lymph node status and histological type.

CONCLUSION

miR-21 expression could predict the prognostic outcome of NSCLC in Asians, despite some deficiencies in the study data.

Combined microRNA in situ hybridization and immunohistochemical detection of protein markers

MicroRNAs are short (18-23 nucleotides) non-coding RNAs involved in posttranscriptional regulation of gene expression through their specific binding to the 3'UTR of mRNAs. MicroRNAs can be detected in tissues using specific locked nucleic acid (LNA)-enhanced probes. The characterization of microRNA expression in tissues by in situ detection is often crucial following a microRNA biomarker discovery phase in order to validate the candidate microRNA biomarker and allow better interpretation of its molecular functions and derived cellular interactions. The in situ hybridization data provides information about contextual distribution and cellular origin of the microRNA. By combining microRNA in situ hybridization with immunohistochemical staining of protein markers, it is possible to precisely characterize the microRNA expressing cells and to identify the potential microRNA targets. This combined technology can also help to monitor changes in the level of potential microRNA targets in a therapeutic setting. In this chapter we present a fluorescence-based technology that allows the combination of microRNA in situ hybridization with immunohistochemistry exemplified by the in situ detection of miR-21 and miR-205 in combination with PDCD4 and smooth muscle a-actin.

Impact of the tumor necrosis factor receptor-associated protein 1 (Trap1) on renal DNaseI shutdown and on progression of murine and human lupus nephritis

Recent findings show that transformation of mild glomerulonephritis into end-stage disease coincides with shutdown of renal DNaseI expression in (NZBxNZW)F1 mice. Down-regulation of DNaseI results in reduced chromatin fragmentation and deposition of extracellular chromatin fragments in glomerular basement membranes where they appear in complex with IgG antibodies. Here, we implicate the anti-apoptotic and survival protein, tumor necrosis factor receptor-associated protein 1 (Trap1) in the disease process, based on the observation that annotated transcripts from this gene overlap with transcripts from the DNaseI gene. Furthermore, we translate these observations to human lupus nephritis. In this study, mouse and human DNaseI and Trap1 mRNA levels were determined by real-time quantitative PCR and compared with protein expression levels and clinical data. Cellular localization was analyzed by immune electron microscopy, IHC, and in situ hybridization. Data indicate that silencing of DNaseI gene expression correlates inversely with expression of the Trap1 gene. Our observations suggest that the mouse model is relevant for the aspects of disease progression in human lupus nephritis. Acquired silencing of the renal DNaseI gene has been shown to be important for progression of disease in both the murine and human forms of lupus nephritis. Early mesangial nephritis initiates a cascade of inflammatory signals that lead to up-regulation of Trap1 and a consequent down-regulation of renal DNaseI by transcriptional interference.

Clinical impact of serum exosomal microRNA-21 as a clinical biomarker in human esophageal squamous cell carcinoma

BACKGROUND

Exosomes are 40-nm to 100-nm membrane vesicles that are secreted by various cells, and they play a major role in cell-cell communication. The objective of this study was to clarify the significance of the levels of microRNA in exosomes extracted from the sera of patients with esophageal squamous cell cancer (ESCC).

METHODS

The authors isolated exosomes in serum samples from patients who had ESCC and from patients who had benign diseases without systemic inflammation. Total RNA was purified from the exosomes, and expression levels of microRNA-21 (miR-21) were analyzed by quantitative real-time polymerase chain reaction.

RESULTS

Serum exosomes from patients with ESCC induced the proliferation of ESCC cells in vitro. The expression levels of exosomal miR-21 were significantly higher in patients with ESCC than those with benign diseases with and without (C-reactive protein <0.3 mg/dL) systemic inflammation. MiR-21 was not detected in serum that remained after exosome extraction. Exosomal miR-21 expression was correlated with advanced tumor classification, positive lymph node status, and the presence of metastasis with inflammation or and clinical stage without inflammation (C-reactive protein <0.3 mg/dL).

CONCLUSIONS

The current results confirmed that exosomal miR-21 expression is up-regulated in serum from patients with ESCC versus serum from patients who have benign diseases without systemic inflammation. Exosomal miR-21 was positively correlated with tumor progression and aggressiveness, suggesting that it may be a useful target for cancer therapy. Cancer 2013. © 2012 American Cancer Society.

MicroRNAs: relevant tools for a colorectal surgeon?

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

The role of microRNAs in colorectal cancer

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

The role of microRNAs in colorectal cancer

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