Elevated microRNA-31 expression regulates colorectal cancer progression by repressing its target gene SATB2. PLoS One. 2013;8:e85353. [PMID: 24386467 PMCID: PMC3875556 DOI: 10.1371/journal.pone.0085353]

MicroRNA-31 functions as an oncogenic microRNA in cutaneous squamous cell carcinoma cells by targeting RhoTBT1

Cutaneous squamous cell carcinoma (cSCC) is a malignancy of epidermal keratinocytes that is responsible for ~20% of annual skin cancer-associated mortalities. Accumulating evidence demonstrates that the dysregulation of micro (mi)RNAs serves a significant role in the tumorigenesis and progression of human cSCC. MicroRNA-31 (miR-31) is upregulated in cSCC and is involved in cSCC development. However, the underlying mechanism remains unclear. The present study demonstrated that miR-31 is upregulated in the cSCC cell line, A-431, and that miR-31 expression contributes to the cell proliferation and invasion of cSCC. In addition, bioinformatics combined with dual luciferase reporter analysis was applied to determine that the tumor suppressor RhoTBT1 was a direct target of miR-31. In addition, miR-31 mimics reduced RhoBTB1 expression in A-431 cells. The results of MTT and Transwell assays demonstrated that knockdown of RhoBTB1 by short interfering RNA induced cell proliferation and invasion in A-431 cells. These results indicated that suppression of RhoBTB1 may be involved in cSCC tumorigenesis, which was directly affected by miR-31. In conclusion, the present study provides evidence that miR-31 acts as an oncogene through direct repression of RhoTBT1 expression in cSCC cancer, suggesting a potential application of miR-31 in prognosis prediction and its therapeutic application in cSCC.

Nanogel-antimiR-31 conjugates affect colon cancer cells behaviour

Soft nanogels, produced by electron beam irradiation, are conjugated to the inhibitor of miR-31, an important molecule in colorectal cancer progression. AntimiR-31 interacts with its biological target in vitro, without being detached from the nanogel.

miRNA Expression Change in Dorsal Root Ganglia After Peripheral Nerve Injury

The role of microRNAs (miRNAs) in the regulation of nerve injury-induced neuropathic pain is unclear. The aims of this study were to assess and compare miRNA expression profiles in dorsal root ganglia (DRG) following three different kinds of peripheral nerve injury, including spinal nerve ligation (SNL), dorsal root transection (DRT), and ventral root transection (VRT), in Sprague-Dawley rats. Responses to thermal and mechanical stimuli were measured preoperatively and on postoperative days (PODs) 1, 4, and 7. A miRNA microarray analysis was used to detect the miRNA expression profiles in injured L5 DRG from SNL, DRT, and VRT on POD 7. Validation of miRNA expression was performed by qPCR and in situ hybridization. Rats receiving SNL displayed significantly higher mechanical hypersensitivity, but those receiving DRT developed higher thermal hypersensitivity. The number of miRNAs that were significantly upregulated in L5 DRG was 49 (7.2%), 25 (3.7%), and 146 (21.5%) following SNL, DRT, and VRT, respectively. On the other hand, 35 (5.1%) miRNAs were significantly downregulated in the SNL group, 21 (3.1%) miRNAs in the DRT group, and 41 (6.0%) miRNAs in the VRT group. Of the four miRNAs that were mutually aberrant in all three models, two were significantly upregulated (twofold), miR-21 and miR-31, and two were significantly downregulated, miR-668 and miR-672. Using in situ hybridization, miRNA-21, miRNA-31, miRNA-668, and miRNA-672 were found to localize to neurons in the DRG. Collectively, the mutual abnormal miRNA expression of miR-21, miR-31, miR-668, and miR-677 implied that these miRNAs may be therapeutic targets for alleviating multiple forms of neuropathic pain.

Single-Molecule Localization Microscopy allows for the analysis of cancer metastasis-specific miRNA distribution on the nanoscale

We describe a novel approach for the detection of small non-coding RNAs in single cells by Single-Molecule Localization Microscopy (SMLM). We used a modified SMLM–setup and applied this instrument in a first proof-of-principle concept to human cancer cell lines. Our method is able to visualize single microRNA (miR)-molecules in fixed cells with a localization accuracy of 10–15 nm, and is able to quantify and analyse clustering and localization in particular subcellular sites, including exosomes. We compared the metastasis-site derived (SW620) and primary site derived (SW480) human colorectal cancer (CRC) cell lines, and (as a proof of principle) evaluated the metastasis relevant miR-31 as a first example. We observed that the subcellular distribution of miR-31 molecules in both cell lines was very heterogeneous with the largest subpopulation of optically acquired weakly metastatic cells characterized by a low number of miR-31 molecules, as opposed to a significantly higher number in the majority of the highly metastatic cells.

Furthermore, the highly metastatic cells had significantly more miR-31-molecules in the extracellular space, which were visualized to co-localize with exosomes in significantly higher numbers. From this study, we conclude that miRs are not only aberrantly expressed and regulated, but also differentially compartmentalized in cells with different metastatic potential. Taken together, this novel approach, by providing single molecule images of miRNAs in cellulo can be used as a powerful supplementary tool in the analysis of miRNA function and behaviour and has far reaching potential in defining metastasis-critical subpopulations within a given heterogeneous cancer cell population.

Special AT-rich sequence-binding protein 2 acts as a negative regulator of stemness in colorectal cancer cells

AIM

To find the mechanisms by which special AT-rich sequence-binding protein 2 (SATB2) influences colorectal cancer (CRC) metastasis.

METHODS

Cell growth assay, colony-forming assay, cell adhesion assay and cell migration assay were used to evaluate the biological characteristics of CRC cells with gain or loss of SATB2. Sphere formation assay was used to detect the self-renewal ability of CRC cells. The mRNA expression of stem cell markers in CRC cells with upregulated or downregulated SATB2 expression was detected by quantitative real-time polymerase chain reaction. Chromatin immunoprecipitation (ChIP) was used to verify the binding loci of SATB2 on genomic sequences of stem cell markers. The Cancer Genome Atlas (TCGA) database and our clinical samples were analyzed to find the correlation between SATB2 and some key stem cell markers.

RESULTS

Downregulation of SATB2 led to an aggressive phenotype in SW480 and DLD-1 cells, which was characterized by increased migration and invasion abilities. Overexpression of SATB2 suppressed the migration and invasion abilities in SW480 and SW620 cells. Using sequential sphere formation assay to detect the self-renewal abilities of CRC cells, we found more secondary sphere formation but not primary sphere formation in SW480 and DLD-1 cells after SATB2 expression was knocked down. Moreover, most markers for stem cells such as CD133, CD44, AXIN2, MEIS2 and NANOG were increased in cells with SATB2 knockdown and decreased in cells with SATB2 overexpression. ChIP assay showed that SATB2 bound to regulatory elements of CD133, CD44, MEIS2 and AXIN2 genes. Using TCGA database and our clinical samples, we found that SATB2 was correlated with some key stem cell markers including CD44 and CD24 in clinical tissues of CRC patients.

CONCLUSION

SATB2 can directly bind to the regulatory elements in the genetic loci of several stem cell markers and consequently inhibit the progression of CRC by negatively regulating stemness of CRC cells.

miRNA-99b-5p suppresses liver metastasis of colorectal cancer by down-regulating mTOR

Liver metastasis is common in patients diagnosed with colorectal cancer (CRC), and is also correlated with poor outcome. In this study we screened the different expression profiles of microRNAs (miRNAs) on the development of liver metastasis in CRC patients. miR-99b-5p was found to be more than 6-fold higher in primary tumors than in matched liver metastases (P = 0.007). Expression of miR-99b-5p in primary tumors of patients with stage III CRC without liver metastases was higher than in CRC patients with liver metastases (P = 0.028). Up-regulated miR-99b-5p was associated with longer overall survival (P = 0.01). Besides, miR-99b-5p silencing in miR-99b-5p-positive CRC cell lines promoted cell migration and up-regulated mTOR, and vice versa. In addition, luciferase assays demonstrated that miR-99b-5p functioned as a tumor suppressor by targeting mTOR. Taken together, our results demonstrate thatmiR-99b-5p is differently expressed in primary CRC and liver metastasis and functions as a tumor-suppressive microRNA in metastatic CRC. The miR-99b-5p–mTOR axis may serve as a prognostic factor and therapeutic target for anti-metastatic therapy in CRC patients.

Function and regulation of microRNA-31 in development and disease

MicroRNAs (miRNAs) are small noncoding RNAs that orchestrate numerous cellular processes both under normal physiological conditions as well as in diseases. This review summarizes the functional roles and transcriptional regulation of the highly evolutionarily conserved miRNA, microRNA-31 (miR-31). miR-31 is an important regulator of embryonic implantation, development, bone and muscle homeostasis, and immune system function. Its own regulation is disrupted during the onset and progression of cancer and autoimmune disorders such as psoriasis and systemic lupus erythematosus. Limited studies suggest that miR-31 is transcriptionally regulated by epigenetics, such as methylation and acetylation, as well as by a number of transcription factors. Overall, miR-31 regulates diverse cellular and developmental processes by targeting genes involved in cell proliferation, apoptosis, cell differentiation, and cell motility. Mol. Reprod. Dev. 83: 654-674, 2016 © 2016 Wiley Periodicals, Inc.

miR-449a inhibits colorectal cancer progression by targeting SATB2

miR-449a has been reported to act as a tumor suppressor in several cancers, however, it is controversial whether it inhibits tumor growth in colorectal cancer. The mechanisms underlying its expression and functions in colorectal cancers are still largely unknown. SATB2 is a sensitive and specific marker for CRC diagnosis. However, the mechanisms by which the expression and functions of SATB2 are regulated still remain to be clarified. We investigated the expression and functional significance of miR-449a and SATB2 and the mechanisms of their dysregulation in human CRC cells. miR-449a overexpression or SATB2 depletion inhibited tumor growth and promoted apoptosis in colorectal tumor cells in vitro and in xenograft mouse model, partially by downregulating SATB2. Expression of miR-449a was increased epigenetically via knocking down their targets, particularly SATB2. miR-449a was downregulated and STAB2 expression was upregulated in human CRCs. Their expressions were significantly associated with overall survival of CRC patients. Our findings demonstrate the existence of a miR-449a-SATB2 negative feedback loop that maintains low levels of miR-449a as well as high level of SATB2, thereby promoting CRC development.

CCAT1: a pivotal oncogenic long non-coding RNA in human cancers

Long non-coding RNAs (lncRNAs) compose a group of non-protein-coding RNAs - more than 200 nucleotides in length. Recent studies have shown that lncRNAs play important roles in different cellular processes, including proliferation, differentiation, migration and invasion. Deregulation of lncRNAs has been widely reported in human tumours, in which they are able to function as either oncogenes (on the one hand) or tumour suppressor genes (on the other). Deregulation of CCAT1 (colon cancer-associated transcript-1), an oncogenic lncRNA, has been documented in different types of malignancy, such as gastric cancer, colorectal cancer and hepatocellular carcinoma. In this regard, enforced expression of CCAT1 exerts potent tumorigenic effects by promoting cell proliferation, invasion and migration. Recent evidence has also shown that CCAT1 may serve as a prognostic cancer biomarker. In this review, we provide an overview of current evidence relating to the role and biological function of CCAT1 in tumour development.

miR-211 suppresses hepatocellular carcinoma by downregulating SATB2

Dysregulation of microRNAs (miRs) is involved in carcinogenesis. Deregulation of miR-211 has recently been observed in many tumors, but its function in hepatocellular carcinoma (HCC) is still unknown. Here we found that miR-211 was decreased in HCC cancer tissues compared with adjacent normal tissues. We also found that overexpression of miR-211 repressed proliferation and invasion in HepG2 and SMMC7721 cells. Luciferase reporter assays and western blot indicated that special AT-rich sequence-binding protein-2 (SATB2), is a direct target of miR-211. The expression of SATB2 was upregulated in HCC cancer tissues and cell lines and miR-211 levels inversely correlated with SATB2 levels in HCC. Importantly, SATB2 rescued the miR-211-mediated inhibition of cell invasion and proliferation. Finally, reintroduction of miR-211 repressed tumor formation of HCC in xenograft mice. This study provides insights into molecular mechanisms that miR-211 contributed to HCC.

MicroRNA-31 initiates lung tumorigenesis and promotes mutant KRAS-driven lung cancer

MicroRNA (miR) are important regulators of gene expression, and aberrant miR expression has been linked to oncogenesis; however, little is understood about their contribution to lung tumorigenesis. Here, we determined that miR-31 is overexpressed in human lung adenocarcinoma and this overexpression independently correlates with decreased patient survival. We developed a transgenic mouse model that allows for lung-specific expression of miR-31 to test the oncogenic potential of miR-31 in the lung. Using this model, we observed that miR-31 induction results in lung hyperplasia, followed by adenoma formation and later adenocarcinoma development. Moreover, induced expression of miR-31 in mice cooperated with mutant KRAS to accelerate lung tumorigenesis. We determined that miR-31 regulates lung epithelial cell growth and identified 6 negative regulators of RAS/MAPK signaling as direct targets of miR-31. Our study distinguishes miR-31 as a driver of lung tumorigenesis that promotes mutant KRAS-mediated oncogenesis and reveals that miR-31 directly targets and reduces expression of negative regulators of RAS/MAPK signaling.

Molecular mechanisms of microRNAs in regulating epithelial-mesenchymal transitions in human cancers

The epithelial-mesenchymal transition (EMT) provides a strong driving force in the progression of various human cancers and the development of chemoresistance. Recently, numbers of studies have demonstrated that microRNAs (miRNAs), by post-transcriptionally silencing EMT-related molecules, can promote or inhibit the EMT process and play pivotal roles in effectively manipulating the occurrence, development, invasion, and metastasis of cancers. MiRNAs can also control the EMT or be controlled by genetic modification and mutual regulation, especially negative feedback. Therefore, miRNAs can be viewed as either oncogenes or tumor suppressor genes to facilitate or retard the EMT, resulting in far-reaching impact on tumor metastasis and effective diagnosis, treatment, and prognosis.

Non-coding landscapes of colorectal cancer

For two decades Vogelstein’s model has been the paradigm for describing the sequence of molecular changes within protein-coding genes that would lead to overt colorectal cancer (CRC). This model is now too simplistic in the light of recent studies, which have shown that our genome is pervasively transcribed in RNAs other than mRNAs, denominated non-coding RNAs (ncRNAs). The discovery that mutations in genes encoding these RNAs [i.e., microRNAs (miRNAs), long non-coding RNAs, and circular RNAs] are causally involved in cancer phenotypes has profoundly modified our vision of tumour molecular genetics and pathobiology. By exploiting a wide range of different mechanisms, ncRNAs control fundamental cellular processes, such as proliferation, differentiation, migration, angiogenesis and apoptosis: these data have also confirmed their role as oncogenes or tumor suppressors in cancer development and progression. The existence of a sophisticated RNA-based regulatory system, which dictates the correct functioning of protein-coding networks, has relevant biological and biomedical consequences. Different miRNAs involved in neoplastic and degenerative diseases exhibit potential predictive and prognostic properties. Furthermore, the key roles of ncRNAs make them very attractive targets for innovative therapeutic approaches. Several recent reports have shown that ncRNAs can be secreted by cells into the extracellular environment (i.e., blood and other body fluids): this suggests the existence of extracellular signalling mechanisms, which may be exploited by cells in physiology and pathology. In this review, we will summarize the most relevant issues on the involvement of cellular and extracellular ncRNAs in disease. We will then specifically describe their involvement in CRC pathobiology and their translational applications to CRC diagnosis, prognosis and therapy.

Epigenetic Alterations in Colorectal Cancer: Emerging Biomarkers

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. One of the fundamental processes driving the initiation and progression of CRC is the accumulation of a variety of genetic and epigenetic changes in colonic epithelial cells. Over the past decade, major advances have been made in our understanding of cancer epigenetics, particularly regarding aberrant DNA methylation, microRNA (miRNA) and noncoding RNA deregulation, and alterations in histone modification states. Assessment of the colon cancer "epigenome" has revealed that virtually all CRCs have aberrantly methylated genes and altered miRNA expression. The average CRC methylome has hundreds to thousands of abnormally methylated genes and dozens of altered miRNAs. As with gene mutations in the cancer genome, a subset of these epigenetic alterations, called driver events, are presumed to have a functional role in CRC. In addition, the advances in our understanding of epigenetic alterations in CRC have led to these alterations being developed as clinical biomarkers for diagnostic, prognostic, and therapeutic applications. Progress in this field suggests that these epigenetic alterations will be commonly used in the near future to direct the prevention and treatment of CRC.

MicroRNA-200c and microRNA-31 regulate proliferation, colony formation, migration and invasion in serous ovarian cancer

BACKGROUND

Serous epithelial ovarian cancer (SEOC) is a highly metastatic disease and its progression has been implicated with microRNAs. This study aimed to identify the differentially expressed microRNAs in Malaysian patients with SEOC and examine the microRNAs functional roles in SEOC cells.

METHODS

Twenty-two SEOC and twenty-two normal samples were subjected to miRNA expression profiling using the locked nucleic acid (LNA) quantitative real-time PCR (qPCR). The localization of miR-200c was determined via LNA in situ hybridization (ISH). Functional analysis of miR-200c and miR-31 on cell proliferation, migration and invasion and clonogenic cell survival were assessed in vitro. The putative target genes of the two miRNAs were predicted by miRWalk program and expression of the target genes in SEOC cell lines was validated.

RESULTS

The miRNA expression profiling revealed thirty-eight significantly dysregulated miRNAs in SEOC compared to normal ovarian tissues. Of these, eighteen were up-regulated whilst twenty miRNAs were down-regulated. We observed chromogenic miR-200c-ISH signal predominantly in the cytoplasmic compartment of both epithelial and inflammatory cancer cells. Re-expression of miR-200c significantly increased the cell proliferation and colony formation but reduced the migration and invasion of SEOC cells. In addition, miR-200c expression was inversely proportionate with the expression of deleted in liver cancer-1 (DLC-1) gene. Over-expression of miR-31 in SEOC cells resulted in decreased cell proliferation, clonogenic potential, cell migration and invasion. Meanwhile, miR-31 gain-of-function led to the down-regulation of AF4/FMR2 family member 1 (AFF1) gene.

CONCLUSIONS

These data suggested that miR-200c and miR-31 may play roles in the SEOC metastasis biology and could be considered as promising targets for therapeutic purposes.

MiR-320e is a novel prognostic biomarker in colorectal cancer

Background:

Advances in early detection and treatment have improved outcomes in patients with colorectal cancer (CRC). However, there remains a need for robust prognostic and predictive biomarkers. We conducted a systematic discovery and validation of microRNA (miRNA) biomarkers in two clinical trial cohorts of CRC patients.

Methods:

We performed an initial ‘discovery' phase using Affymetrix miRNA expression arrays to profile stage III CRC patients with and without tumour recurrence (n=50 per group) at 3-years of follow-up. All patients received adjuvant 5-fluorouracil (5-FU) plus oxaliplatin, that is, FOLFOX, treatment. During ‘validation', we analysed miRNAs using qRT–PCR in an independent cohort of 237 stage II–IV CRC patients treated with 5-FU-based chemotherapy, as well as in normal colonic mucosa from 20 healthy subjects. Association with disease recurrence, disease-free survival (DFS) and overall survival (OS) was examined using Cox proportional hazard models.

Results:

In the discovery cohort, miR-320e expression was significantly elevated in stage III colon cancers from patients with vs without recurrence (95% confidence interval (CI)=1.14–1.42; P<0.0001). These results were then independently validated in stage II and III tumours. Specifically, increased miR-320e expression was associated with poorer DFS (hazard ratio (HR)=1.65; 95% CI=1.27–2.13; P=0.0001) and OS (HR=1.78; 95% CI=1.31–2.41; P=0.0003) in stage III CRC patients.

Conclusions:

In two clinical trial cohorts, a systematic biomarker discovery and validation approach identified miR-320e to be a novel prognostic biomarker that is associated with adverse clinical outcome in stage III CRC patients treated with 5-FU-based adjuvant chemotherapy. These findings have important implications for the personalised management of CRC patients.

Epithelial-mesenchymal transition in colorectal cancer metastasis: A system review

Tumor metastasis is a multi-step process by which tumor cells disseminate from their primary site and form secondary tumors at a distant site. And metastasis is the major cause of death in the vast majority of cancer patients. However, the mechanisms underlying each step remain obscure. In the past decade, a developmental program epithelial-to-mesenchymal transition (EMT) has been increasingly recognized to play pivotal and intricate roles in promoting carcinoma invasion and metastasis. The EMT process is very complex and controlled by various families of transcriptional regulators through different signaling pathways. In this system review, we focus on the molecular network of the EMT program and its malignant phenotypes associated with metastasis in colorectal cancer (CRC), including cancer stem cells, tumor budding, circulating tumor cells and drug resistance. A better understanding of the molecular regulation of the dynamic EMT program during tumor metastasis will help to provide much-needed therapeutic interventions to target this program when treating metastatic CRC.

Regulative Effect of Mir-205 on Osteogenic Differentiation of Bone Mesenchymal Stem Cells (BMSCs): Possible Role of SATB2/Runx2 and ERK/MAPK Pathway

Bone mesenchymal stem cells (BMSCs) have multiple potentials to differentiate into osteoblasts and adipocytes, and methods to enhance their osteogenic differentiation are gaining increasing attention. MicroRNAs are critical regulation factors during the process of the osteogenic induction in BMSCs, and mir-205 has been substantiated to be involved in the osteogenic process, but the underlying mechanisms remain unclear. The purpose of this article is to investigate the role of mir-205 in the osteogenic differentiation of BMSCs. We found that mir-205 expression was down-regulated in a time-dependent manner during BMSC osteo-induction. Inhibition of mir-205 enhanced osteogenic abilities by up-regulating bone sialoprotein (BSP) and osteopontin (OPN) protein levels and increasing alkaline phosphatase (ALP) activity and osteocalcin secretion. Furthermore, we found that mir-205 could regulate protein expression of special AT-rich sequence-binding protein 2 (SATB2) and runt-related transcription factor 2 (Runx2), and over-expression of SATB2 activated Runx2 and reversed the negative effects of mir-205 on osteoblastic differentiation. Furthermore, we examined the extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38 MAPK) pathways during osteogenic induction and our data indicates that mir-205 might exert negative functions on the osteogenic differentiation in BMSCs at least partly via altering phosphorylation of ERK and p38 MAPK. These results shed new light on the molecular mechanisms of microRNAs in governing differentiation of BMSCs.

An update on miRNAs as biological and clinical determinants in colorectal cancer: a bench-to-bedside approach

Colorectal carcinogenesis represents a sequential progression of normal colonic mucosa from adenoma to carcinoma. It has become apparent that miRNA deregulation contributes to the initiation and progression of colorectal cancer (CRC). These oncogenic or tumor-suppressive miRNAs interact with intracellular signaling networks and lead to alteration of cell proliferation, apoptosis, metastasis and even response to chemotherapeutic treatments. This article aims to review the cutting edge progress in the discovery of the role of novel mechanisms for miRNAs in the development of CRC. We will also discuss the potential use of miRNAs as biomarkers for early diagnosis and prognosis of CRC. Furthermore, with advancements in RNA delivery technology, it is anticipated that manipulation of miRNAs may offer an alternative therapy for CRC treatment.

SATB1 and 2 in colorectal cancer

The special AT-rich sequence-binding proteins 1 and 2 (SATB1/2) are nuclear matrix associated proteins that are transcription factors involved in chromatin remodeling and gene regulation. Expression of the SATB2 gene is tissue-specific, and the only epithelial cells expressing SATB2 are the glandular cells of the lower gastrointestinal tract where its expression is regulated by microRNA-31 (miR-31) and miR-182. SATB2, along with its homolog SATB1, are thought to be involved in various cancers with their roles in this disease being specific to the type of cancer. Colorectal cancer (CRC) provides the largest association of SATB2 with cancer and the roles of SATB2 are better defined and more studied in CRC than in any other cancer type. SATB1 displays a negative association with SATB2 in CRC. The various studies that have investigated the involvement of SATB1 and 2 in CRC have produced consistent findings. Here, we form four major conclusions regarding the role of these proteins in CRC and their potential clinical value: (i) SATB2 is a sensitive marker to distinguish CRC from other cancer types, (ii) Reduced expression of SATB2 in CRC is associated with poor prognosis, (iii) High levels of SATB1 expression facilitate CRC and are associated with poor prognosis and (iv) Overexpression of miR-31 and -182 in CRC leads to more aggressive cancer. This review will describe several of the key investigations that established these conclusions and highlight results that offer opportunities for future research in the treatment and diagnosis of CRC.

Emerging paradigms of long non-coding RNAs in gastrointestinal cancer

A large number of long non-coding RNAs (lncRNAs) have been discovered by genome-wide transcriptional analyses. Emerging evidence has indicated that lncRNAs regulate gene expression at epigenetic, transcription, and post-transcription levels, are widely involved in various pathobiology of human diseases, and may play an important role in the biology of cancer stem cells. Alterations of specific lncRNAs have been revealed to interact with the major pathways of cell proliferation, apoptosis, differentiation, invasion and metastasis in many human malignancies, such as gastrointestinal cancer. This review summarizes the current understandings in biological functions and implications of lncRNAs in gastrointestinal cancer.

Prognostic role of microRNA-31 in various cancers: a meta-analysis

To date, many studies have shown that microRNAs (miRNA) exhibit altered expression levels in various cancers and may play a potential role as diagnostic and prognostic biomarkers of cancers. This meta-analysis was designed to evaluate the exact role of microRNA-31 (miR-31) for survival and discuss the possibility of utilizing miR-31 to predict the prognosis of patients with various human cancers. Electronic literature databases including PubMed, Web of Science, and Embase were searched for articles published until May 2014. The articles only written in English were considered. Data were extracted from studies comparing overall survival (OS), cancer-specific survival (CSS), or postoperative survival (PS) in patients with multiple cancers, which showed higher miR-31 expression than with similar patients. Pooled hazard ratios (HRs) of miR-31 for survival and 95 % confidence intervals (CI) were calculated. Ten studies with a total of 1,648 participants were included for the meta-analysis. For OS, the pooled HRs of higher miR-31 expression in cancers indicated significant predictor poorer survival in general cancers in either univariate analysis (HR=2.34, 95 % CI=1.15-3.52, P<0.05) or multivariate analysis (HR=1.15, 95 % CI=1.04-1.26, P<0.05). For CSS, elevated miR-31 was also a significant predictor to general cancers in multivariate analysis (HR=1.77, 95 % CI=1.06-2.47, P<0.05). And, no association was found between miR-31 expression and PS. In conclusion, the present findings indicate that high miR-31 expression is associated with poor OS and CSS in patients with general cancers and miR-31 may be a useful clinical prognostic biomarker.

Epigenetics of colorectal cancer

Colorectal cancer is a common type of gastrointestinal cancer with high incidence. It is generally considered that colorectal cancer develops through a multistep process that results from the progressive accumulation of mutations and epigenetic changes. The genes in colorectal cancer are more frequently affected by altered epigenetics than by mutations. In this review, we will discuss epigenetic changes of colorectal cancer, aiming to provide new ideas for the prevention, diagnosis, treatment and prognosis of this malignancy.

Increased expression of miRNA-182 in colorectal carcinoma: an independent and tissue-specific prognostic factor

Increasing evidence has revealed that miRNAs play a pivotal role in multiple processes of carcinogenesis, and are being explored as diagnostic, prognostic and predictive biomarker. In this study, we investigated the status of miR-182 expression in colorectal carcinoma (CRC) by in situ hybridization and its underlying clinicopathologic significance for patients with CRC. We found that 79/138 (57.25%) CRCs had high-level expression of miR-182, while 17/67 (25.37%) normal mucosa tissues had high-level expression of miR-182. The expression level of miR-182 was remarkably up-regulated in CRC tissues compared with non-neoplastic normal tissues (P < 0.001). The over-expression of miR-182 in cancer parenchyma cells in CRC were strongly correlated with T-stage (P = 0.020), lymph node metastasis (P = 0.003), distant metastasis (P = 0.002), and Dukes' stage (P = 0.005) in patients with CRC. Patients with high-level expression of miR-182 had short overall survival time than those with low-level expression of miR-182 (P < 0.001). Univariate and multivariate survival analyses further showed that miR-182 expression was a potential unfavorable prognostic factor for CRC, suggesting a potential application of miR-182 in prognosis prediction and therapeutic application in CRC.

microRNA-182 targets special AT-rich sequence-binding protein 2 to promote colorectal cancer proliferation and metastasis

Background

Increasing evidence has revealed that microRNAs (miRNA) played a pivotal role in regulating cancer cell proliferation and metastasis. The deregulation of miR-182 has been identified in colorectal cancer (CRC). However, the role and mechanism of miR-182 in CRC have not been completely understood yet.

Methods

The expression levels of miR-182 in CRC tissues and CRC cell lines were examined by performing stem-loop quantitative RT-PCR. The stable over-expression miR-182 cell lines and control cell lines were constructed by lentivirus infection. Subsequently, CCK-8 assay, plate colony formation assay, cell migration, invasion assay and experimental animal models were performed to detect the biological functions of miR-182 in vitro and in vivo. A luciferase reporter assay was conducted to confirm target associations. Western blot and immunohistochemical analysis were performed to examine the expression changes of molecular markers that are regulated by miR-182.

Results

We found that miR-182 expression is increased in CRC cells that originated from metastatic foci and human primary CRC tissues with lymph node metastases. The ectopic expression of miR-182 enhanced cell proliferation, invasion, and migration in vitro. Stable overexpression of miR-182 also facilitated tumor growth and metastasis in vivo too. Further research showed that miR-182 could directly target the 3’untranslated region (3’UTR) of SATB2 mRNA and subsequently repress both the mRNA and protein expressions of SATB2, which we identified in previous studies as a CRC metastasis-associated protein. Restoring SATB2 expression could reverse the effects of miR-182 on CRC cell proliferation and migration. Investigations of possible mechanisms underlying these behaviors induced by miR-182 revealed that miR-182 induced epithelial-mesenchymal transition (EMT) by modulating the expression of key cellular molecules in EMT.

Conclusions

Our results illustrated that the up-regulation of miR-182 played a pivotal role in CRC tumorigenesis and metastasis, which suggesting a potential implication of miR-182 in the molecular therapy for CRC.

MicroRNA-215 is a potential prognostic marker for cervical cancer

Recently, microRNAs (miRNAs) have been shown to be involved in multiple biological pathways that can influence tumor progression and metastasis and they can serve as prognostic biomarkers in many cancers. The present study examined the prognostic significance of miR-215 in cervical cancer. The paraffin-embedded paired cervical scrape samples and tumor tissue samples from 302 patients with stage II cervical cancer were detected for the expression of miR-215 by using qRT-PCR. A miR-215-based classifier was established by using the Cox regression model. The prognostic and predictive accuracy of this classifier was determined in both the internal testing group of 138 patients, and the external independent group of 280 patients. Moreover, cervical cancer HeLa cells overexpressing miR-215 (HeLa-miR-215) were constructed and subcutaneously injected into the nude mice to examine the effect of miR-215 on tumor growth and metastasis in vivo. The results showed that the expression level of miR-215 was significantly higher in cervical cancer tissues than in paired normal tissues (P<0.0001). When patients were classified into high- and low-risk cancer progression groups according to miR-215 level, the 5-year disease-free survival in high- and low-risk groups were 43% (95% CI: 32.1-51.6) and 67% (95% CI: 48.6-77.3) (hazard ratio [HR] 2.02, 95% CI: 1.16-3.52; P=0.013) respectively. Moreover, the expression level of miR-215 was negatively associated with survival rate in patients at TNM stage T3 (HR: 3.317; 95% CI: 1.18-5.14, P=0.017) and TNM stage T4 (HR: 3.48; 95% CI: 1.49-4.45, P=0.008). Tumor volume in nude mice injected with HeLa-miR-215 cells was significantly larger than that in mice injected with control HeLa cells. It was concluded that the expression level of miR-215 is associated with cervical tumor progression and worse survival rate, suggesting that it may serve as a potential prognostic marker to identify patients at higher risk of recurrence.