MiR-21 regulates biological behavior through the PTEN/PI-3 K/Akt signaling pathway in human colorectal cancer cells

Expression of miR-34a-5p is up-regulated in human colorectal cancer and correlates with survival and clock gene PER2 expression

Colorectal cancer represents a leading cause of cancer death. MicroRNAs (miRNAs) are small non-coding RNA molecules that have been extensively studied in tumours, since changes in their levels can reveal patient prognosis. Cancer progression is also influenced by the circadian system whose functioning is based on the rhythmic expression of clock genes. Therefore, we performed macroarray screening of tumour and adjacent tissues in patients undergoing surgery for colorectal carcinoma. We identified 17 miRNAs showing expression that was more than 100 times higher in tumour tissue compared to adjacent tissue. From in silico analysis, miR-34a-5p was selected as showing a computer-predicted interaction with PER2. Real-time PCR revealed a negative correlation between expression of PER2 mRNA and miR-34a in patients with more advanced cancer stage. Expression of miR-34a was up-regulated in cancer tissue compared to adjacent tissue. High miR-34a expression was associated with better survival of patients. miR-34a showed lower expression levels in male patients with lymph node involvement, and a trend towards decreased expression in male patients with distant metastases. Male patients, but not female patients, with high expression of miR-34a and who were free of distant metastases and/or lymph node involvement showed better survival. Therefore, we proposed that expression of miR-34a was regulated in a sex-dependent manner and could be considered a marker of prognosis in earlier cancer stages in male patients.

Emerging roles of microRNAs in regulating the mTOR signaling pathway during tumorigenesis

The mammalian target of rapamycin (mTOR) is a large Ser/Thr protein kinase that belongs to the phosphoinositide 3-kinase (PI3K) family and mediates various physiological and pathological processes, especially cell proliferation, protein synthesis, autophagy, and cancer development. The mTOR expression is transient and tightly regulated in normal cells, but it is overactivated in cancer cells. Recently, several studies have indicated that microRNAs (miRNAs) play a critical role in the regulation of mTOR and mTOR-associated processes, some acting as inhibitors and the others as activators. Although it is still in infancy, the strategy of combining both miRNAs and mTOR inhibitors might provide an approach to selectively sensitizing tumor cells to chemotherapy-induced DNA damage and subsequently attenuating the tumor cell growth and apoptosis.

MicroRNAs, intestinal inflammatory and tumor

Colorectal cancer (CRC) is the third most malignant tumor. Inflammatory bowel disease (IBD) can increase the risk of colorectal cancer. And colitis-associated cancer (CAC) is a CRC subtype, representing the inflammation-related colorectal cancer. For the past decades, we have known that ectopic microRNA (miRNA) expression was involved in the pathogenesis of IBD and CRC, playing a pivotal role in the progression of inflammation to colorectal cancer. Thus, this review provides the recent advances in altered human tissue-specific miRNAs that contribute to IBD, CRC and CAC pathogenesis, diagnosis and treatment. Meanwhile, the potential utilization of miRNAs as novel therapeutic targets for the prevention of CRC was also discussed.

The diagnostic efficacy of circulating miRNAs in monitoring the early development of colitis-induced colorectal cancer

Early detection of colorectal cancer and monitoring the progress in colon carcinogenesis stages is essential to reduce mortality. Therefore, there is continuous search for noninvasive biomarkers with high stability and good sensitivity and specificity. miRNAs have attracted attention as promising biomarkers as they are stably expressed in circulation. The aim of our study is to evaluate the aberrant expression of circulating miRNAs during the stepwise progress of colitis-associated colon cancer. This was accomplished through assessing the expression levels of five miRNAs (miR-141, miR-15b, miR-17-3p, miR-21, and miR-29a) in serum and their corresponding tissue samples through the different cycles of colorectal carcinogenesis cascade using the azoxymethane/dextran sulfate sodium murine model. We also compared the diagnostic performance of these selected miRNAs with the conventional tumor biomarkers CEA and CA 19-9. The results of our study revealed that the expression levels of those miRNAs were dynamically changing in accordance with the tumor development state. Moreover, their aberrant expression in serum was statistically correlated with that in tissue. Our data also revealed that serum miR-15b, miR-21, and miR-29a showed the best performance in terms of diagnostic power. Our findings highlight the efficiency of these circulating miRNAs not only for early diagnostics purposes, but also for monitoring progress in the colorectal carcinogenesis process, and therefore encouraging integrating these noninvasive biomarkers into the clinical diagnostic settings beside the traditional diagnostic markers for accurate screening of the early progress of colon carcinogenesis.

Small non-coding RNA and colorectal cancer

Colorectal cancer (CRC) is the third most common malignance. Although great efforts have been made to understand the pathogenesis of CRC, the underlying mechanisms are still unclear. It is now clear that more than 90% of the total genome is actively transcribed, but lack of protein‐coding potential. The massive amount of RNA can be classified as housekeeping RNAs (such as ribosomal RNAs, transfer RNAs) and regulatory RNAs (such as microRNAs [miRNAs], PIWI‐interacting RNA [piRNAs], tRNA‐derived stress‐induced RNA, tRNA‐derived small RNA [tRFs] and long non‐coding RNAs [lncRNAs]). Small non‐coding RNAs are a group of ncRNAs with the length no more than 200 nt and they have been found to exert important regulatory functions under many pathological conditions. In this review, we summarize the biogenesis and functions of regulatory sncRNAs, such as miRNAs, piRNA and tRFs, and highlight their involvements in cancers, particularly in CRC.

Mir20a/106a-WTX axis regulates RhoGDIa/CDC42 signaling and colon cancer progression

Wilms tumor gene on the X chromosome (WTX) is a putative tumor suppressor gene in Wilms tumor, but its expression and functions in other tumors are unclear. Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in women and the second leading cause in men in the United States. We demonstrated that WTX frequently lost in CRC which was highly correlated with cell proliferation, tumor invasion and metastasis. Mechanistically, WTX loss disrupts the interaction between RhoGDIα and CDC42 by losing of the binding with RhoGDIα and triggers the activation of CDC42 and its downstream cascades, which promotes CRC development and liver metastasis. The aberrant upregulation of miR-20a/miR-106a were identified as the reason of WTX loss in CRC both in vivo and in vitro. These study defined the mechanism how miR-20a/miR-106a-mediated WTX loss regulates CRC progression and metastasis, and provided a potential therapeutic target for preventing CRC progression.

Genetic variant in miR-21 binding sites is associated with colorectal cancer risk

Single nucleotide polymorphisms (SNPs) within binding sites of microRNAs (miRNAs) could modify cancer susceptibility by changing the binding affinity of miRNAs on their target mRNA 3'-untranslated regions (UTRs). MicroRNA-21 (miR-21) is involved in the development of colorectal cancer. However, the relationship between SNPs within the binding sites of miR-21 and colorectal cancer risk has not been widely investigated. A case-control study including 1147 patients and 1203 controls was performed to evaluate the association of SNPs in miR-21 binding sites and colorectal cancer risk. Dual-luciferase reporter assays and functional assays were performed to evaluate the effects of miR-21. The SNP rs6504593 C allele conferred an increased risk of colorectal cancer compared with the T allele in an additive model (odds ratio [OR] = 1.19, 95% confidence interval [CI] = 1.04-1.36, P = 0.011). Dual-luciferase reporter assays demonstrated that the rs6504593 T allele negatively post-transcriptionally regulated IGF2BP1 by altering the binding affinity of miR-21. Additionally, colorectal cancer cells transiently transfected with miR-21 mimics promoted cell proliferation and suppressed apoptosis, whereas inhibition of miR-21 decreased cell growth. These data suggest that the miR-21 binding site SNP rs6504593 in the IGF2BP1 3'-UTR may alter IGF2BP1 expression and contribute to colorectal cancer risk.

Small RNA sequencing of sessile serrated polyps identifies microRNA profile associated with colon cancer

Sessile serrated adenoma/polyps (SSA/Ps) of the colon account for 20-30% of all colon cancers. Small non-coding RNAs, including microRNAs (miRNAs), may function as oncogenes or tumor suppressor genes involved in cancer development. Small RNA sequencing (RNA-seq) was used to characterize miRNA profiles in SSA/Ps, hyperplastic polyps (HPs), adenomatous polyps and paired uninvolved colon. Our 108 small RNA-seq samples' results were compared to small RNA-seq data from 212 colon cancers from the Cancer Genome Atlas. Twenty-three and six miRNAs were differentially expressed in SSA/Ps compared to paired uninvolved colon and HPs, respectively. Differential expression of MIR31-5p, MIR135B-5p and MIR378A-5p was confirmed by RT-qPCR. SSA/P-specific miRNAs are similarly expressed in colon cancers containing genomic aberrations described in serrated cancers. Correlation of miRNA expression with consensus molecular subtypes suggests more than one subtype is associated with the serrated neoplasia pathway. Canonical pathway analysis suggests many of these miRNAs target growth factor signaling pathways.

The Dual Role of MicroRNAs in Colorectal Cancer Progression

Colorectal cancer (CRC) is responsible for one of the major cancer incidence and mortality worldwide. It is well known that MicroRNAs (miRNAs) play vital roles in maintaining the cell development and other physiological processes, as well as, the aberrant expression of numerous miRNAs involved in CRC progression. MiRNAs are a class of small, endogenous, non-coding, single-stranded RNAs that bind to the 3’-untranslated region (3′-UTR) complementary sequences of their target mRNA, resulting in mRNA degradation or inhibition of its translation as a post-transcriptional regulators. Moreover, miRNAs also can target the long non-coding RNA (lncRNA) to regulate the expression of its target genes involved in proliferation and metastasis of CRC. The functions of these dysregulated miRNAs appear to be context specific, with evidence of having a dual role in both oncogenes and tumor suppression depending on the cellular environment in which they are expressed. Therefore, the unique expression profiles of miRNAs relate to the diagnosis, prognosis, and therapeutic outcome in CRC. In this review, we focused on several oncogenic and tumor-suppressive miRNAs specific to CRC, and assess their functions to uncover the molecular mechanisms of tumor initiation and progression in CRC. These data promised that miRNAs can be used as early detection biomarkers and potential therapeutic target in CRC patients.

LINC00312 represses proliferation and metastasis of colorectal cancer cells by regulation of miR-21

Long non‐coding RNAs (lncRNAs) have emerged as important regulators of cancer, including colorectal cancer (CRC). The exact expression pattern of long intergenic noncoding RNA 00312 (LINC00312) in CRC and its mechanisms of action have not been reported. Here, we found that LINC00312 is underexpressed in CRC tissues and cell lines. Functional experiments suggested that LINC00312 suppresses growth, migration and invasion of CRC cells in vitro and attenuates tumour proliferation and metastasis in vivo. Mechanistically, LINC00312 was found to regulate the malignancy of CRC cells by binding to miR‐21 and by functioning as a tumour suppressor targeting PTEN. Overexpression of miR‐21 or knockdown of PTEN attenuated the LINC00312‐mediated inhibition of CRC cell proliferation and invasion. Taken together, our results elucidate the role of the LINC00312–miR‐21–PTEN axis in CRC cell proliferation and tumour progression and may lead to new lncRNA‐based diagnostics or therapeutics for CRC.

Overexpression of miR-21-5p promotes proliferation and invasion of colon adenocarcinoma cells through targeting CHL1

Background

This study aims to investigate the effect of miR-21-5p on process of colon adenocarcinoma (COAD) cells and its connection with neural cell adhesion molecule L1 (CHL1).

Methods

Different expressions of mRNAs and miRNAs were calculated with microarray analysis. QRT-PCR and western blot were performed to quantify miR-21-5p and CHL1 expression. Flow Cytometry, MTT assay, colony formation assay, transwell assay and ELISA were performed to evaluate propagation and invasiveness of COAD cells. Dual luciferase reporter assay was employed to scrutinize the relationship between miR-21-5P and CHL1. We performed in vivo experiment to detect the impact of miR-21-5p and CHL1 on COAD tumor growth.

Results

Expression level of miR-21-5p increased in both COAD tissues and cells. MTT and Cell cycle assay showed that overexpression of miR-21-5p accelerated proliferation of COAD cells. Transwell assay indicated that miR-21-5p promoted cell invasion. The result of dual luciferase reporter assay indicated that miR-21-5p targeted CHL1 directly and inhibited its expression. The result of in vivo experiments showed that down-regulation of miR-21-5p decreased the volume and weight of tumor, while knockdown of CHLI stimulated tumor growth.

Conclusions

The overexpression of miR-21-5p can promote propagation and invasiveness of COAD cells through inhibiting the expression of CHL1.

The Role of Autophagy and Related MicroRNAs in Inflammatory Bowel Disease

Accumulating evidence demonstrates that microRNA- (miR-) mediated posttranscriptional regulation plays an important role in autophagy in inflammatory bowel disease (IBD), a disease that is difficult to manage clinically because of the associated chronic recurrent nonspecific inflammation. Research indicates that microRNAs regulate autophagy via different pathways, playing an important role in the IBD process and providing a new perspective for IBD research. Related studies have shown that miR-142-3p, miR-320, miR-192, and miR-122 target NOD2, an IBD-relevant autophagy gene, to modulate autophagy in IBD. miR-142-3p, miR-93, miR-106B, miR-30C, miR-130a, miR-346, and miR-20a regulate autophagy by targeting ATG16L1 through several different pathways. miR-196 can downregulate IRGM and suppress autophagy by inhibiting the accumulation of LC3II. During the endoplasmic reticulum stress response, miR-665, miR-375, and miR-150 modulate autophagy by regulating the unfolded protein response, which may play an important role in IBD intestinal fibrosis. Regarding autophagy-related pathways, miR-146b, miR-221-5p, miR-132, miR-223, miR-155, and miR-21 regulate NF-κB or mTOR signaling to induce or inhibit autophagy in intestinal cells by releasing anti- or proinflammatory factors, respectively.

Inhibition of miR-21 ameliorates excessive astrocyte activation and promotes axon regeneration following optic nerve crush

Optic nerve injury is a leading cause of irreversible visual impairment worldwide and can even cause blindness. Excessive activation of astrocytes has negative effects on the repair and recovery of retinal ganglion cells following optic nerve injury. However, the molecular and cellular mechanisms underlying astrocyte activation after optic nerve injury remain largely unknown. In the present study, we explored the effects of microRNA-21 (miR-21) on axon regeneration and flash visual evoked potential (F-VEP) and the underlying mechanisms of these effects based on astrocyte activation in the rat model of optic nerve crush (ONC). To the best of our knowledge, this article is the first to report that inhibition of miR-21 enhances axonal regeneration and promotes functional recovery in F-VEP in the rat model of ONC. Furthermore, inhibition of miR-21 attenuates excessive astrocyte activation and glial scar formation, thereby promoting axonal regeneration by regulating the epidermal growth factor receptor (EGFR) pathway. In addition, we observed that the expression of tissue inhibitor of metalloproteinase-3, a target gene of miR-21, was inhibited during this process. Taken together, these findings demonstrate that inhibition of miR-21 regulates the EGFR pathway, ameliorating excessive astrocyte activation and glial scar progression and promoting axonal regeneration and alleviating impairment in F-VEP function in a model of ONC. This study's results suggest that miR-21 may represent a therapeutic target for optic nerve injury.

Exosomal microRNA-32-5p induces multidrug resistance in hepatocellular carcinoma via the PI3K/Akt pathway

BACKGROUND

Multidrug resistance is the main obstacle for hepatocellular carcinoma (HCC) treatment. miR-32-5p is involved in HCC progression but its function in multidrug resistance is still unclear. Here we aim to find out the function of miR-32-5p in inducing multidrug resistance and its underlying mechanisms of transforming sensitive cell to resistant cell.

METHODS

We detected the expression of miR-32-5p and PTEN in the multidrug-resistant cell line (Bel/5-FU) and the sensitive cell line (Bel7402), HCC and para-carcinoma liver tissues through real-time PCR. Dual-luciferase reporter assay verified PTEN is the target of miR-32-5p. Exosomes from sensitive and multidrug resistant cell line were obtained and confirmed through ultracentrifuge and Nano Analyzer. Gain- and loss-of-function experiments, rescue experiments, a PI3K/Akt pathway inhibitor, an exosome biogenesis inhibitor, and nude mice xenograft models were used to determine the underlying mechanisms of miR-32-5p and PTEN, as well as exosomal miR-32-5p in inducing multidrug resistance in vitro and in vivo.

RESULTS

miR-32-5p was significantly elevated but PTEN was reduced in Bel/5-FU. An inverse correlation between miR-32-5p and PTEN was confirmed in HCC cell lines and patients; moreover, high expression of miR-32-5p and low expression of PTEN were positively associated with poor prognosis. Over-expression of miR-32-5p activated the PI3K/Akt pathway by suppressing PTEN and induced multidrug resistance via exosomes through promoting angiogenesis and epithelial-mesenchymal transition (EMT).

CONCLUSIONS

Our study demonstrated that the multidrug-resistant cell, Bel/5-FU delivers miR-32-5p to sensitive cell, Bel7402 by exosomes and activates the PI3K/Akt pathway to further induce multidrug resistance by modulating angiogenesis and EMT.

Over-Expression of miR-21 and Lower PTEN Levels in Wilms' Tumor with Aggressive Behavior

Wilms' tumor (WT) is the most common pediatric kidney tumor. MiR-21 is one of the most frequently overexpressed microRNAs in solid tumors, while phosphatase and tensin homolog deleted from chromosome 10 (PTEN) is the most highly mutated tumor suppressor gene. The aim of this study was to investigate the relationship between miR-21 and PTEN in WT. The expression levels of miR-21 and the PTEN protein were determined by qRT-PCR and Western blot analyses in WT specimens, respectively. In WT tissues, the miR-21 expression levels were significantly higher and the PTEN protein levels were significantly lower, compared to the adjacent non-tumorous renal tissues. The higher levels of miR-21 and lower levels of PTEN were correlated with age (> 24 months), late clinical stage, unfavorable histopathological type and lymphatic metastasis. A univariate linear regression analysis indicated a significant correlation between higher miR-21 levels and lower PTEN levels. Using the SK-NEP-1 WT cell line, we showed that the decreased expression levels of miR-21 promoted cell proliferation and invasion, but inhibited apoptosis. Importantly, lowered expression levels of miR-21 increased the expression levels of PTEN protein and decreased the expression levels of phosphoinositide 3-kinase (PI3K) and phosphorylated protein kinase B (p-AKT), each of which functions in the downstream signaling pathway. Dual luciferase-reporter assays indicated that PTEN mRNA was a direct target of miR-21. In conclusion, higher miR-21 levels and lower PTEN protein levels are predictive biomarkers for poor prognosis of WT patients. Over-expression of miR-21 promotes aggressive behavior of WT by targeting PTEN.

miR‑21‑5p regulates type II alveolar epithelial cell apoptosis in hyperoxic acute lung injury

Hyperoxia-induced acute lung injury (HALI) as one of the most common complications in patents on mechanical ventilation, and there are no efficient methods to overcome this at present. It was hypothesized that microRNA 21-5p(miR-21-5p) can promote the survival of type II alveolar epithelial cells (AECII), alleviating HALI. The present study aimed to combine gene chip analysis with the overexpression miR-21-5p to develop a novel therapeutic option for HALI. It was found that AECII apoptosis was an important pathogenic event in the development of HALI, and the overexpression of miR-21-5p prevented HALI, associated with reducing AECII apoptosis. These results were obtained using adenoviral/lentiviral vectors, which overexpressed miR-21-5p, to transfect AECII cells in vitro and in vivo. It was found that the overexpression of miR-21-5p reduced the apoptotic rate of the AECII cells. In addition, miR-21-5p decreased the ratio of B-cell lymphoma 2 (Bcl-2)-associated X protein/Bcl-2 and the expression of caspase-3. It was also revealed that the overexpression of miR-21-5p alleviated acute lung injury in adult rats exposed to a hyperoxic environment. These results suggest that miR-21-5p may become a novel therapeutic option for patients with HALI, by protecting AECII cells from apoptosis.

Role of Microbiome in Carcinogenesis Process and Epigenetic Regulation of Colorectal Cancer

Epigenetic changes during the development of colorectal cancer (CRC) play a significant role. Along with factors such as diet, lifestyle, and genetics, oncogenic infection, bacteria alone or whole microbiome, has been associated with this tumor type. How gut microbiome contributes to CRC pathogenesis in the host is not fully understood. Most of the epigenetic studies in CRC have been conducted in populations infected with Helicobacter pylori. In the current review, we summarize how the gut microbiota contributes in colon carcinogenesis and the potential role of epigenetic mechanism in gene regulation. We discuss microbiota-mediated initiation and progression of colon tumorigenesis and have also touched upon the role of microbial metabolites as an initiator or an inhibitor for procarcinogenic or antioncogenic activities. The hypothesis of gut microbiota associated CRC revealed the dynamic and complexity of microbial interaction in initiating the development of CRC. In the multifaceted processes of colonic carcinogenesis, gradual alteration of microbiota along with their microenvironment and the potential oncopathogenic microbes mediated modulation of cancer therapy and other factors involved in microbiome dysbiosis leading to the CRC have also been discussed. This review provides a comprehensive summary of the mechanisms of CRC development, the role of microbiome or single bacterial infection in regulating the processes of carcinogenesis, and the intervention by novel therapeutics. Epigenetic mechanism involved in CRC is also discussed.

MicroRNAs in the etiology of colorectal cancer: pathways and clinical implications

MicroRNAs (miRNAs) are small single-stranded RNAs that repress mRNA translation and trigger mRNA degradation. Of the ∼1900 miRNA-encoding genes present in the human genome, ∼250 miRNAs are reported to have changes in abundance or altered functions in colorectal cancer. Thousands of studies have documented aberrant miRNA levels in colorectal cancer, with some miRNAs reported to actively regulate tumorigenesis. A recurrent phenomenon with miRNAs is their frequent participation in feedback loops, which probably serve to reinforce or magnify biological outcomes to manifest a particular cellular phenotype. Here, we review the roles of oncogenic miRNAs (oncomiRs), tumor suppressive miRNAs (anti-oncomiRs) and miRNA regulators in colorectal cancer. Given their stability in patient-derived samples and ease of detection with standard and novel techniques, we also discuss the potential use of miRNAs as biomarkers in the diagnosis of colorectal cancer and as prognostic indicators of this disease. MiRNAs also represent attractive candidates for targeted therapies because their function can be manipulated through the use of synthetic antagonists and miRNA mimics.

Summary: This Review provides an overview of some important microRNAs and their roles in colorectal cancer.

miR-21 Inhibitors Modulate Biological Functions of Gastric Cancer Cells via PTEN/PI3K/mTOR Pathway

Gastric cancer is one of the most common malignancy in the world. microRNAs (miRNAs) are naturally occurring noncoding RNA that control gene expression by targeting messenger RNA (mRNA) for post-transcriptional repression or cleavage. This study focused on a specific miRNA, miR-21, which was overexpressed in gastric cancer and examined the effects of miR-21 inhibitor on biological functions of gastric cancer cells and its possible mechanism. Gastric cancer cells MKN74 were treated with miR-21 inhibitor, negative control, and blank control. Cell proliferation, colony formation, migration, and invasion were assessed. Real-time PCR and western blot were applied to examine the expression of phosphatase and tens in homolog deleted on chromosome ten (PTEN)/PI3K/mTOR pathway molecules. miR-21 inhibitor markedly suppressed proliferation, migration, invasion, and colony formation of gastric cancer cells. Anti-miR-21 treatment also reduced the expression ratio of B cell lymphoma 2 (Bcl-2)/Bax. Furthermore, miR-21 inhibition was associated with increased expression of PTEN, which in turn decreased the ratios of S235/236, S240/244, and p-AK/AKT in gastric cancer cells. Inhibiting miR-21 modulates biological functions of gastric cancer cells via PTEN/PI3K/mTOR pathway and miR-21 inhibitor may provide a novel therapeutic strategy for gastric cancer.

MicroRNAs and their role for T stage determination and lymph node metastasis in early colon carcinoma

Worldwide, colon cancer is among the most common cancer entities. Understanding the molecular background is the key to enable accurate stage determination, which is crucial to assess optimal therapy options. The search for preoperative biomarkers is ongoing. In recent years, several studies have proposed a diagnostic and prognostic role for miRNAs in cancer. Aim of this study was to evaluate miRNA expression patterns correlating with tumor stage, especially lymph node metastasis, in primary colon carcinoma tissue. Screening was accomplished using GeneChip^® miRNA v3.0 arrays (Thermo Fisher Scientific, Waltham, MA, USA) and validated via TaqMan^® qPCR assays (Thermo Fisher Scientific, Waltham, MA, USA) to investigate miRNA expressions in 168 FFPE and 83 fresh frozen colon carcinoma samples. Regarding lymph node status, analyses displayed no significantly differential miRNA expression. Interestingly, divergent expression of miR-18a-5p, miR-20a-5p, miR-21-5p, miR-152-3p and miR-1973 was detected in stage pT1. Although miRNAs might not represent reliable biomarkers regarding lymph node metastasis status, they could support risk assessment in stage T1 tumors.

MicroRNA-21: A Positive Regulator for Optimal Production of Type I and Type III Interferon by Plasmacytoid Dendritic Cells

Plasmacytoid dendritic cells (pDCs) are the major producers of type I and type III interferons (IFNs) that play essential roles in host antiviral immunity. MicroRNAs (miRs) are small, noncoding RNAs that can modulate many immune processes. Although molecular regulation of type I IFN production by pDCs has been studied extensively, the regulation of type III IFN production has not been studied thoroughly, particularly at posttranscriptional level. We show here that miR-21 is an essential positive regulator for the production of both IFN-α and IFN-λ by pDCs and for promoting host defense against viral infection. miR-21 was markedly upregulated in toll-like receptor (TLR)-activated pDCs and was crucial for TLR7/9 ligand- or herpesvirus-induced production of IFN-α and IFN-λ by pDCs. miR-21-deficient pDCs produced significantly lower levels of IFN-α and IFN-λ on activation than those by wild-type pDCs. Impaired antiviral immune responses were also observed in miR-21-deficient mice. Mechanistically, we identified phosphatase and tensin homolog (PTEN) as the major target of miR-21 in pDCs, and miR-21 deficiency resulted in increased expression of PTEN that suppressed TLR-mediated activation of PI3K-Akt-mTOR signaling in pDCs. Hence, our findings provide evidence that miR-21 positively regulates both IFN-α and IFN-λ production and identify an important role for miR-21 in regulating the function of pDCs and in host antiviral immunity.

The Role of MicroRNAs in the Chemopreventive Activity of Sulforaphane from Cruciferous Vegetables

Colorectal cancer is an increasingly significant cause of mortality whose risk is linked to diet and inversely correlated with cruciferous vegetable consumption. This is likely to be partly attributable to the isothiocyanates derived from eating these vegetables, such as sulforaphane, which is extensively characterised for cytoprotective and tumour-suppressing activities. However, its bioactivities are likely to extend in complexity beyond those currently known; further insight into these bioactivities could aid the development of sulforaphane-based chemopreventive or chemotherapeutic strategies. Evidence suggests that sulforaphane modulates the expression of microRNAs, many of which are known to regulate genes involved at various stages of colorectal carcinogenesis. Based upon existing knowledge, there exist many plausible mechanisms by which sulforaphane may regulate microRNAs. Thus, there is a strong case for the further investigation of the roles of microRNAs in the anti-cancer effects of sulforaphane. There are several different types of approach to the wide-scale profiling of microRNA differential expression. Array-based methods may involve the use of RT-qPCR or complementary hybridisation probe chips, and tend to be relatively fast and economical. Cloning and deep sequencing approaches are more expensive and labour-intensive, but are worth considering where viable, for their greater sensitivity and ability to detect novel microRNAs.

Potential roles of microRNAs and ROS in colorectal cancer: diagnostic biomarkers and therapeutic targets

As one of the most commonly diagnosed cancers worldwide, colorectal adenocarcinoma often occurs sporadically in individuals aged 50 or above and there is an increase among younger patients under 50. Routine screenings are recommended for this age group to improve early detection. The multifactorial etiology of colorectal cancer consists of both genetic and epigenetic factors. Recently, studies have shown that the development and progression of colorectal cancer can be attributed to aberrant expression of microRNA. Reactive oxygen species (ROS) that play a key role in cancer cell survival, can also lead to carcinogenesis and cancer exacerbations. Given the rapid accumulating knowledge in the field, an updated review regarding microRNA and ROS in colorectal cancer is necessary. An extensive literature search has been conducted in PubMed/Medline databases to review the roles of microRNAs and ROS in colorectal cancer. Unique microRNA expression in tumor tissue, peripheral blood, and fecal samples from patients with colorectal cancer is outlined. Therapeutic approaches focusing on microRNA and ROS in colorectal cancer treatment is also delineated. This review aims to summarize the newest knowledge on the pathogenesis of colorectal cancer in the hopes of discovering novel diagnostic biomarkers and therapeutic techniques.

Clinicopathological parameters and prognostic relevance of miR-21 and PTEN expression in Wilms' tumor

BACKGROUND

MiR-21 is one of the most often found miRNAs overexpressed in solid tumors, while PTEN is the most highly mutated tumor suppressor gene. Our purpose was to examine the expression levels of miR-21 and PTEN protein in Wilms' tumor (WT) and in para-tumoral tissues and to investigate the relationships among miR-21, PTEN expression, clinicopathological parameters and the prognosis of patients with WT.

METHODS

The expression levels of miR-21 and PTEN protein in WT and corresponding para-tumoral tissues were investigated by qRT-PCR and Western blot, respectively. Differences in patient survival were determined using the Kaplan-Meier method and the log-rank test. A Cox proportional hazards regression analysis was used for univariate and multivariate analyses of prognostic values.

RESULTS

Compared with para-tumoral renal tissues, the expression levels of miR-21 were significantly upregulated in WT tissues, while the PTEN protein were significantly downregulated (P<0.05). Analyses of the clinicopathological parameters showed that the miR-21 expression level was significantly associated with age, late clinical stage, histopathological tumor type and lymphatic metastasis (P<0.05). PTEN protein expression was significantly associated with age, late clinical stage and histopathological tumor type (P<0.05). The univariate linear regression analysis illustrated a significant negative correlation between miR-21 and PTEN expression (r=-0.687, P<0.05). The Kaplan-Meier curve showed that patients with high miR-21 and low PTEN protein expression survived significantly longer (P<0.05). However, a multivariate analysis suggested that neither the expression level of miR-21 nor that of PTEN is an independent prognostic factor for overall survival.

CONCLUSIONS

Both upregulated miR-21 and downregulated PTEN expression have a possible correlation with the aggressive progression and poor prognosis of WT, which suggests that upregulated miR-21 and downregulated PTEN expression may be valuable markers of tumor progression and indicators of the prognosis of WT.

miR-543 promotes colorectal cancer proliferation and metastasis by targeting KLF4

Till now, miR-543 expression has been demonstrated to be involved in the development of some cancers. However, reports about its expression and mechanism in colorectal cancer (CRC) were conflicting [1, 2]. Here, we investigated clinical implications of miR-543 and mechanisms underlying miR-543-mediated CRC development. In this study, real-time quantitative PCR (qRT-PCR) validated miR-543 was highly expressed in CRC samples and cell lines. MiR-543 was closely associated with tumor size, TNM stage and metastasis. In addition, survival analysis showed that high miR-543 expression was obviously correlated with poor overall survival and disease-free survival. Mechanically, downregulation of miR-543 by miR-543 inhibitor obviously repressed cell proliferation, promoted apoptosis, affected migration and invasion. Moreover, luciferase reporter analysis identified that Krüppel-like Factor-4 (KLF4) was a direct target of miR-543, and there was an obvious inverse correlation between miR-543 and KLF4 expression in CRC tissues. Furthermore, KLF4 down-regulation favors miR-543-induced oncogenic effect on cell proliferation, apoptosis, migration, and invasion. In conclusion, this study indicated that miR-543 facilitates colorectal cancer proliferation and metastasis by targeting KLF4, and miR-543 may serve as a promising target for the treatment of CRC patients.

Non-coding RNAs Enabling Prognostic Stratification and Prediction of Therapeutic Response in Colorectal Cancer Patients

Colorectal cancer (CRC) is a heterogeneous disease and current treatment options for patients are associated with a wide range of outcomes and tumor responses. Although the traditional TNM staging system continues to serve as a crucial tool for estimating CRC prognosis and for stratification of treatment choices and long-term survival, it remains limited as it relies on macroscopic features and cases of surgical resection, fails to incorporate new molecular data and information, and cannot perfectly predict the variety of outcomes and responses to treatment associated with tumors of the same stage. Although additional histopathologic features have recently been applied in order to better classify individual tumors, the future might incorporate the use of novel molecular and genetic markers in order to maximize therapeutic outcome and to provide accurate prognosis. Such novel biomarkers, in addition to individual patient tumor phenotyping and other validated genetic markers, could facilitate the prediction of risk of progression in CRC patients and help assess overall survival. Recent findings point to the emerging role of non-protein-coding regions of the genome in their contribution to the progression of cancer and tumor formation. Two major subclasses of non-coding RNAs (ncRNAs), microRNAs and long non-coding RNAs, are often dysregulated in CRC and have demonstrated their diagnostic and prognostic potential as biomarkers. These ncRNAs are promising molecular classifiers and could assist in the stratification of patients into appropriate risk groups to guide therapeutic decisions and their expression patterns could help determine prognosis and predict therapeutic options in CRC.

miR-331-3p and Aurora Kinase inhibitor II co-treatment suppresses prostate cancer tumorigenesis and progression

RNA-based therapeutics could represent a new avenue of cancer treatment. miRNA 331-3p (miR-331-3p) is implicated in prostate cancer (PCa) as a putative tumor suppressor, but its functional activity and synergy with other anti-tumor agents is largely unknown. We found miR-331-3p expression in PCa tumors was significantly decreased compared to non-malignant matched tissue. Analysis of publicly available PCa gene expression data sets showed miR-331-3p expression negatively correlated with Gleason Score, tumor stage, lymph node involvement and PSA value, and was significantly down regulated in tumor tissue relative to normal prostate tissue. Overexpression of miR-331-3p reduced PCa cell growth, migration and colony formation, as well as xenograft tumor initiation, proliferation and survival of mice. Microarray analysis identified seven novel targets of miR-331-3p in PCa. The 3’-untranslated regions of PLCγ1 and RALA were confirmed as targets of miR-331-3p, with mutation analyses confirming RALA as a direct target. Expression of miR-331-3p or RALA siRNA in PCa cells reduced RALA expression, proliferation, migration and colony formation in vitro. RALA expression positively correlated with Gleason grade in two separate studies, as well as in a PCa tissue microarray. Co-treatment using siRALA with an Aurora Kinase inhibitor (AKi-II) decreased colony formation of PCa cells while the combination of AKi-II with miR-331-3p resulted in significant reduction of PCa cell proliferation in vitro and PCa xenograft growth in vivo. Thus, miR-331-3p directly targets the RALA pathway and the addition of the AKi-II has a synergistic effect on tumor growth inhibition, suggesting a potential role as combination therapy in PCa.

MicroRNAs in HPV associated cancers: small players with big consequences

INTRODUCTION

MicroRNAs (miRs) are short (~20 nucleotides) non-coding ribonuecleic acids (ncRNAs) known to be involved in cellular processes such as proliferation, differentiation, immune response, pathogenicity and tumourigenesis, among many others. The regulatory mechanisms exerted by miRs have been implicated in many cancers, including Human Papillomavirus (HPV)-associated cancers. Areas covered: In this review, the authors discuss the involvement of miRs (-143, -375, -21, -200, -296 etc.) that have been shown to be dysregulated in HPV-associated cancers. This review also encompasses both intracellular and exosomal miRs, and their potential as diagnostic biomarkers in saliva and blood. The authors have also attempted to dissect the functional impact of miRs on cellular processes such as changes in cellular polarity, loss of apoptosis and tumour suppression, and unchecked and uncontrolled cell cycle regulation, all of which ultimately lead to aberrant cellular proliferation. Expert commentary: Identification of dysregulated miRs in HPV-associated cancers opens up new opportunities to develop diagnostic, therapeutic and prognostic biomarkers. Studies on global expression patterns of miRs dysregulated in HPV-associated cancers can be instrumental in developing broader therapeutic strategies. Therapies like anti-miR, miR-replacement and those based on alternative natural products targeting miRs, need to be improved and better synchronized to be cost-effective and have better treatment outcomes.

Co-delivery of microRNA-21 antisense oligonucleotides and gemcitabine using nanomedicine for pancreatic cancer therapy

Tumor metastasis occurs naturally in pancreatic cancer, and the efficacy of chemotherapy is usually poor. Precision medicine, combining downregulation of target genes with chemotherapy drugs, is expected to improve therapeutic effects. Therefore, we developed a combined therapy of microRNA‐21 antisense oligonucleotides (ASO‐miR‐21) and gemcitabine (Gem) using a targeted co‐delivery nanoparticle (NP) carrier and investigated the synergistic inhibitory effects on pancreatic cancer cells metastasis and growth. Polyethylene glycol–polyethylenimine–magnetic iron oxide NPs were used to co‐deliver ASO‐miR‐21 and Gem. An anti‐CD44v6 single‐chain variable fragment (scFv_CD44v6) was used to coat the particles to obtain active and targeted delivery. Our results showed that the downregulation of the oncogenic miR‐21 by ASO resulted in upregulation of the tumor‐suppressor genes PDCD4 and PTEN and the suppression of epithelial–mesenchymal transition, which inhibited the proliferation and induced the clonal formation, migration, and invasion of pancreatic cancer cells in vitro. The co‐delivery of ASO‐miR‐21 and Gem induced more cell apoptosis and inhibited the growth of pancreatic cancer cells to a greater extent than single ASO‐miR‐21 or Gem treatment in vitro. In animal tests, more scFv_CD44v6‐PEG‐polyethylenimine/ASO‐magnetic iron oxide NP/Gem accumulated at the tumor site than non‐targeted NPs and induced a potent inhibition of tumor proliferation and metastasis. Magnetic resonance imaging was used to observed tumor homing of NPs. These results imply that the combination of miR‐21 gene silencing and Gem therapy using an scFv‐functionalized NP carrier exerted synergistic antitumor effects on pancreatic cancer cells, which is a promising strategy for pancreatic cancer therapy.

XRCC1 Gene Polymorphisms and miR-21 Expression in Patients with Colorectal Carcinoma

OBJECTIVE

The objectives of this study were to evaluate the impact of two X-ray repair cross complementing 1 (XRCC1) gene polymorphisms (Arg194Trp and Arg399Gln) on the risk of development of colorectal cancer (CRC) and to assess the expression levels of microRNA-21 (miR-21) in CRC patients.

MATERIALS AND METHODS

A case-control cross sectional study was conducted on 50 CRC patients and 50 cancer-free subjects. DNA and miR-21 were extracted from whole blood samples. The expression levels of the XRCC1 polymorphisms and miR-21 were assessed by real-time PCR in all subjects of the study.

RESULTS

Genotype analysis revealed a significant association between CRC risk and both the Arg194Trp genotype (OR=11.407, 95% CI=4.039-32.221, p<0.001) and the Arg399Gln genotype (OR=3.778, 95% CI= 1.6-8.919, p=0.002). The expression levels of circulating miR-21 were able to detect CRC cases significantly (p=0.022) with a sensitivity of 82% and a specificity of 56% (Area under the curve (AUC)=0.633) but were unable to distinguish between early and late cases (AJCC classification) (p=0.194).

CONCLUSION

The XRCC1 Arg194Trp and Arg399Gln polymorphisms both confer high susceptibility for the development of CRC. Circulating miR-21 expression levels are a potentially diagnostic non-invasive genetic marker of CRC.

Therapeutic Suppression of miR-4261 Attenuates Colorectal Cancer by Targeting MCC

The mutated in colorectal cancer (MCC) gene is an important colorectal tumor suppressor gene, although few studies have reported the microRNA(s) that could directly target MCC in colorectal cancer. Here, we used microRNA (miRNA) target prediction algorithms, and previously reported microarray data in human colorectal cancer found that only miR-4261 was predicted by all three databases to directly target MCC. Based on specimens from our own cohort of colorectal cancer patients, we further demonstrated that miR-4261 was overexpressed in colorectal cancer. Interestingly, overexpression of miR-4261 could enhance cell proliferation and G1/S phase transition of cell cycle, and promote cell migration in HCT116 and HT29 cells, while inhibition of miR-4261 had opposite effects. Luciferase reporter assay and western blot analysis confirmed MCC as a direct target of miR-4261. MCC small interfering RNA (siRNA) could abolish the suppressive effects of miR-4261 inhibitor on cell proliferation and migration in HCT116 and HT29 cell lines. Finally, we showed that therapeutic intervention with lentivirus-based miR-4261 sponge injection could effectively reduce tumor growth and inhibit cell proliferation in colorectal cancer xenograft. Collectively, our study is the first one to unravel the functional role of miR-4261, and it provides strong evidence that inhibition of miR-4261 through targeting of MCC might exert a therapeutic effect for colorectal cancer.

MicroRNA-186-5p overexpression modulates colon cancer growth by repressing the expression of the FAM134B tumour inhibitor

OBJECTIVES

The role and underlying mechanism of miR-186-5p in colorectal cancer remain unknown. The present study aims to examine the various cellular effects of miR-186-5p in the carcinogenesis of colorectal cancer. Also, the interacting targets and association of clinicopathological factors with miR-186-5p expression in patients with colorectal cancer were analysed.

METHODS

The miR-186-5p expression levels in colorectal cancer tissues (n=126) and colon cancer cell lines (n=3) were analysed by real-time PCR. Matched non-neoplastic colorectal tissues and a non-neoplastic colonic epithelial cell line were used as controls. Various in vitro assays such as cell proliferation, wound healing and colony formation assays were performed to examine the miR-186-5p specific cellular effects. Western blots and immunohistochemistry analysis were performed to examine the modulation of FAM134B, PARP9 and KLF7 proteins expression.

RESULTS

Significant high expression of miR-186-5p was noted in cancer tissues (p< 0.001) and cell lines (p<0.05) when compared to control tissues and cells. The majority of the patients with colorectal cancer (88/126) had shown overexpression of miR-186-5p. This miR-186-5p overexpression was predominantly noted with in cancer with distant metastasis (p=0.001), lymphovascular permeation (p=0.037), microsatellite instability (MSI) stable (p=0.015), in distal colorectum (p=0.043) and with associated adenomas (p=0.047). Overexpression of miR-186-5p resulted in increased cell proliferation, colony formation, wound healing capacities and induced alteration of cell cycle kinetics in colon cancer cells. On the other hand, inhibition of endogenous miR-186-5p reduced the cancer growth properties. miR-186-5p overexpression reduced FAM134B expression significantly in the cancer cells (p<0.01). Also, FAM134B and miR-186-5p expressions are inversely correlated in colorectal cancer tissues and cells.

CONCLUSION

The miR-186-5p expression promotes colorectal cancer pathogenesis by regulating tumour suppressor FAM134B. Reduced cancer cells growth followed by inhibition of miR-186-5p highlights the potential of miR-186-5p inhibitor as a novel strategy for targeting colorectal cancer initiation and progression.

MicroRNAs: Potential candidates for diagnosis and treatment of colorectal cancer

Colorectal cancer (CRC) is known as the third common cancer worldwide and an important public health problem in different populations. Several genetics and environmental risk factors are involved in the development and progression of CRC including chromosomal abnormalities, epigenetic alterations, and unhealthy lifestyle. Identification of risk factors and biomarkers could lead to a better understanding of molecular pathways involved in CRC pathogenesis. MicroRNAs (miRNAs) are important regulatory molecules which could affect a variety of cellular and molecular targets in CRC. A large number of studies have indicated deregulations of some known tissue-specific miRNAs, for example, miR-21, miR-9, miR-155, miR-17, miR-19, let-7, and miR-24 as well as circulating miRNAs, for example, miR-181b, miR-21, miR-183, let-7g, miR-17, and miR-126, in patients with CRC. In the current review, we focus on the findings of preclinical and clinical studies performed on tissue-specific and circulating miRNAs as diagnostic biomarkers and therapeutic targets for the detection of patients at various stages of CRC.

Micro-RNA-21 Regulates Cancer-Associated Fibroblast-Mediated Drug Resistance in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer deaths due to its highly aggressive biological nature and resistance to chemotherapy. Previous studies indicate that miR-21 is an important regulator in the activation of cancer-associated fibroblasts (CAFs). However, whether miR-21 in CAFs would regulate PDAC’s tumor microenvironment and lead to drug resistance remain unknown. In this study, we evaluated the relationship between CAF activation, miR-21 expression, and drug resistance using tumor samples from PDAC patients. We changed the miR-21 expression level in CAFs and tested its roles in regulating the function of CAFs. In addition, we explored the roles of miR-21 in CAFs in the development of PDAC using an animal model. We found that PDAC patients who were resistant to gemcitabine treatment tended to have higher miR-21 expression and more activated CAFs. An in vitro study showed that CAFs with high miR-21 expression had elevated MMP-3, MMP-9, PDGF, and CCL-7 expression and promoted the invasion of PDAC cell lines. miR-21 overexpression also contributed to the activation of CAFs by regulating the PDCD4 gene. The in vivo study showed that upregulating miR-21 in CAFs promoted PDAC desmoplasia and increased its drug resistance to gemcitabine treatment, but downregulating miR-21 in CAFs suppressed desmoplasia and enhanced the effect of gemcitabine. We concluded that miR-21 promoted the activation of CAFs and contributed to the drug resistance of PDAC.

Exosomal transfer of tumor-associated macrophage-derived miR-21 confers cisplatin resistance in gastric cancer cells

BACKGROUND

Cisplatin-based chemotherapy is frequently used to treat advanced gastric cancer (GC). However, the resistance often occurs with the mechanisms being not well understood. Recently, emerging evidence indicates that tumor-associated macrophages (TAMs) play an important role in chemoresistance of cancer. As the important mediators in intercellular communications, exosomes secreted by host cells mediate the exchange of genetic materials and proteins to be involved in tumor aggressiveness. The aim of the study was to investigate whether exosomes derived from TAMs mediate cisplatin resistance in gastric cancer.

METHODS

M2 polarized macrophages were obtained from mouse bone marrow or human PBMCs stimulated with IL-4 and IL-13. Exosomes isolated from M2 macrophages culture medium were characterized, and miRNA expression profiles of M2 derived exosomes (M2-exos) were analyzed using miRNA microarray. In vitro cell coculture was further conducted to investigate M2-exos mediated crosstalk between TAMs and tumor cells. Moreover, the in vivo experiments were performed using a subcutaneous transplantation tumor model in athymic nude mice.

RESULTS

In this study, we showed that M2 polarized macrophages promoted cisplatin (DDP) resistance in gastric cancer cells and exosomes derived from M2 macrophages (M2-exos) are involved in mediating the resistance to DDP. Using miRNA profiles assay, we identify significantly higher levels of microRNA-21 (miR21) isomiRNAs in exosomes and cell lysate isolated from M2 polarized macrophage. Functional studies revealed that exosomal miR-21 can be directly transferred from macrophages to the gastric cancer cells, where it suppresses cell apoptosis and enhances activation of PI3K/AKT signaling pathway by down-regulation of PTEN.

CONCLUSIONS

Our findings suggest that exosomal transfer of tumor-associated macrophages derived miR-21 confer DDP resistance in gastric cancer, and targeting exosome communication may be a promising new therapeutic strategy for gastric cancer patients.

Hepatitis B virus X protein increases microRNA‑21 expression and accelerates the development of hepatoma via the phosphatase and tensin homolog/phosphoinositide 3‑kinase/protein kinase B signaling pathway

Hepatitis B virus (HBV) X protein (HBx) is a key regulatory protein that is involved in HBV infection, replication and carcinogenesis of hepatocellular carcinoma (HCC). The aim of the present study was to investigate the role of HBx in the progression and metastasis of liver cancer cells and to determine the underlying molecular mechanism of HBx in metastatic liver cancer cells. HBx protein expression was detected by western blot analysis, and microRNA (miR)‑21 levels were determined by reverse transcription‑quantitative polymerase chain reaction in the highly metastatic MHCC‑97H low metastatic MHCC‑97L and SMMC‑7721 liver cancer cell lines. The results demonstrated that the levels of HBx and miR‑21 were significantly increased in MHCC‑97H cells compared with MHCC‑97L and SMMC‑7721 cells. In addition, three pairs of small interfering (si)RNA specific to HBx were designed and synthesized to interfere with endogenous HBx in liver cancer cells, and the results demonstrated that knockdown HBx was associated with a corresponding decrease in miR‑21 expression. The MTT assay results demonstrated that cell viability significantly decreased in HBx‑siRNA cells compared with scramble siRNA‑transfected cells. In addition, transfection with an miR‑21 inhibitor inhibited MHCC‑97H cell proliferation. Furthermore, Transwell assay results revealed that downregulation of HBx and treatment with miR‑21 inhibitors contributed to the inhibition of MHCC‑97H cell invasion and metastasis. Western blot analysis demonstrated that miR‑21 inhibitors and HBx‑siRNA treatment led to the upregulation of phosphatase and tensin homolog (PTEN), and decreased levels of phosphoinositide 3‑kinase (PI3K), phosphorylated protein kinase B (Akt) and matrix metalloproteinase (MMP)‑2. The results of the present study indicated that HBx was positively associated with miR‑21 expression, and downregulation of miR‑21 and HBx suppressed MMP‑2 activity via the PTEN/PI3K/Akt signaling pathway. Therefore, HBx and miR‑21 may represent novel therapeutic targets for the treatment of HCC.

Role of miRNAs in human cancer metastasis: Implications for therapeutic intervention

Metastasis is the spread and growth of localized cancer to new locations in the body and is considered the main cause of cancer-related deaths. Metastatic cancer cells display distinct genomic and epigenomic profiles and almost universally an aggressive pathophysiology. A better understanding of the molecular mechanisms and regulation of metastasis, including how metastatic tumors grow and survive in the nascent niche and the interactions of the emergent metastatic cancer cells within the local microenvironment may provide tools to design strategies to restrict metastatic dissemination. Aberrant microRNAs (miRNA) expression has been reported in metastatic cancer cells. MicroRNAs are known to regulate divergent and/or convergent metastatic gene pathways including activation of reprogramming switches during metastasis. An in-depth understanding of role of miRNAs in the metastatic cascade may lead to the identification of novel targets for anti-metastatic therapeutics as well as potential candidate miRNAs for cancer treatment. This review primarily focuses on the role of miRNAs in the mechanisms of cancer metastasis as well as implications for metastatic cancer treatment.

Targeting miRNAs by polyphenols: Novel therapeutic strategy for cancer

In the recent years, polyphenols have gained significant attention in scientific community owing to their potential anticancer effects against a wide range of human malignancies. Epidemiological, clinical and preclinical studies have supported that daily intake of polyphenol-rich dietary fruits have a strong co-relationship in the prevention of different types of cancer. In addition to direct antioxidant mechanisms, they also regulate several therapeutically important oncogenic signaling and transcription factors. However, after the discovery of microRNA (miRNA), numerous studies have identified that polyphenols, including epigallocatechin-3-gallate, genistein, resveratrol and curcumin exert their anticancer effects by regulating different miRNAs which are implicated in all the stages of cancer. MiRNAs are short, non-coding endogenous RNA, which silence the gene functions by targeting messenger RNA (mRNA) through degradation or translation repression. However, cancer associated miRNAs has emerged only in recent years to support its applications in cancer therapy. Preclinical experiments have suggested that deregulation of single miRNA is sufficient for neoplastic transformation of cells. Indeed, the widespread deregulation of several miRNA profiles of tumor and healthy tissue samples revealed the involvement of many types of miRNA in the development of numerous cancers. Hence, targeting the miRNAs using polyphenols will be a novel and promising strategy in anticancer chemotherapy. Herein, we have critically reviewed the potential applications of polyphenols on various human miRNAs, especially which are involved in oncogenic and tumor suppressor pathways.

The role of miRNA-21 and epithelial mesenchymal transition (EMT) process in colorectal cancer

AIMS

The study was conducted to assess the expression levels of epithelial mesenchymal transition (EMT) proteins (E-cadherin, N-cadherin, snail-1 and vimentin) and miRNA-21. In addition, we correlated these data with clinicopathological features in Colorectal cancer.

METHODS

H&E slides from a total of 59 formalin fixed paraffin embedded tissue blocks were examined by a pathologist to demarcate normal and tumour regions. Immunohistochemical analysis of mismatch repair proteins (MLH1, MSH2 and MSH6) and EMT markers (E-cadherin, N-cadherin, snail-1 and vimentin) was performed. The miRNA-21 expression levels were determined using qRT-PCR and the data was analysed using the relative quantification method. The Fisher's exact and Pearson's χ² tests were used to correlate snail-1, E-cadherin, miRNA-21 and clinicopathological data.

RESULTS

Our results showed a statistically significant correlation between high miRNA-21 expression levels and E-cadherin positive cases. There was also an association between high miRNA-21 expression levels and negative snail-1 expression. No significant correlation was seen between miRNA-21 expression levels and clinicopathological features. Moreover, high expression levels of miRNA-21 were significantly associated with the sporadic cases.

CONCLUSIONS

Our data suggest that miRNA-21 in association with E-cadherin and snail-1 does not play a significant role in the development and progression of this disease.

Clinical value of integrated-signature miRNAs in colorectal cancer: miRNA expression profiling analysis and experimental validation

MicroRNA (miRNA) expression profiling of colorectal cancer (CRC) are often inconsistent among different studies. To determine candidate miRNA biomarkers for CRC, we performed an integrative analysis of miRNA expression profiling compared CRC tissues and paired neighboring noncancerous colorectal tissues. Using robust rank aggregation method, we identified a miRNA set of 10 integrated-signature miRNAs. In addition, the qRT-PCR validation demonstrated that 9 miRNAs were consistent dysregulated with the integrative analysis in CRC tissues, 4 miRNAs (miR-21-5p, miR-183-5p, miR-17-5p and miR-20a-5p) were up-regulated expression, and 5 miRNAs (miR-145-5p, miR-195-5p, miR-139-5p, miR-378a-5p and miR-143-3p) were down-regulated expression (all p < 0.05). Consistent with the initial analysis, 7 miRNAs were found to be significantly dysregulated in CRC tissues in TCGA data base, 4 miRNAs (miR-21-5p, miR-183-5p, miR-17-5p and miR-20a-5p) were significantly up-regulated expression, and 3 miRNAs (miR-145-5p, miR-139-5p and miR-378a-5p) were significantly down-regulated expression in CRC tissues (all p < 0.001). Furthermore, miR-17-5p (p = 0.011) and miR-20a-5p (p = 0.003) were up-regulated expression in the III/IV tumor stage, miR-145-5p (p = 0.028) and miR-195-5p (p = 0.001) were significantly increased expression with microscopic vascular invasion in CRC tissues, miR-17-5p (p = 0.037) and miR-145-5p (p = 0.023) were significantly increased expression with lymphovascular invasion. Moreover, Cox regression analysis of CRC patients in TCGA data base showed miR-20a-5p was correlated with survival (hazard ratio: 1.875, 95%CI: 1.088-3.232, p = 0.024). Hence, the finding of current study provides a basic implication of these miRNAs for further clinical application in CRC.

Identification of a Novel lincRNA-p21-miR-181b-PTEN Signaling Cascade in Liver Fibrosis

Previously, we found that long intergenic noncoding RNA-p21 (lincRNA-p21) inhibits hepatic stellate cell (HSC) activation and liver fibrosis via p21. However, the underlying mechanism of the antifibrotic role of lincRNA-p21 in liver fibrosis remains largely unknown. Here, we found that lincRNA-p21 expression was significantly downregulated during liver fibrosis. In LX-2 cells, the reduction of lincRNA-p21 induced by TGF-β1 was in a dose- and time-dependent manner. lincRNA-p21 expression was reduced in liver tissues from patients with liver cirrhosis when compared with that of healthy controls. Notably, lincRNA-p21 overexpression contributed to the suppression of HSC activation. lincRNA-p21 suppressed HSC proliferation and induced a significant reduction in α-SMA and type I collagen. All these effects induced by lincRNA-p21 were blocked down by the loss of PTEN, suggesting that lincRNA-p21 suppressed HSC activation via PTEN. Further study demonstrated that microRNA-181b (miR-181b) was involved in the effects of lincRNA-p21 on HSC activation. The effects of lincRNA-p21 on PTEN expression and HSC activation were inhibited by miR-181b mimics. We demonstrated that lincRNA-p21 enhanced PTEN expression by competitively binding miR-181b. In conclusion, our results disclose a novel lincRNA-p21-miR-181b-PTEN signaling cascade in liver fibrosis and suggest lincRNA-p21 as a promising molecular target for antifibrosis therapy.

MicroRNA-21 promotes proliferation, migration, and invasion of colorectal cancer, and tumor growth associated with down-regulation of sec23a expression

Background

MicroRNA-21 (miR-21) is up-regulated in many cancers, including colorectal cancer (CRC). Nevertheless, the function of miR-21 in CRC and the mechanism underlying that function is still unclear.

Methods

After analyzing the expression of miR-21 and Sec23A in CRC cell lines, we transfected the highest miR-21 expressing cell line, SW-480, with a plasmid containing an miR-21 inhibitor and the lowest miR-21 expressing cell line, DLD-1, with a plasmid containing an miR-21 mimic and measured the effects on the expression of Sec23A and on cell proliferation, migration, and invasion. We also evaluated the effect of knocking down Sec23A on miR-21 expression and its effects on cell proliferation, migration, and invasion. Finally, we assessed the effect of miR-21 in a xenograft tumor model in mice. Tumor tissues from these mice were subjected to immunohistochemical staining to detect the expression of Sec23A.

Results

Genetic deletion of miR-21 suppressed the proliferation, migration, and invasion of SW-480 cells, while over-expression of miR-21 promoted proliferation, migration, and invasion of DLD-1 cells. Inhibition of miR-21 increased the expression of Sec23A protein in SW-480 cells while over-expression of miR-21 significantly suppressed the expression of Sec23A protein and Sec23A mRNA in DLD-1 cells. Knockdown of Sec23A increased the expression of miR-21 in SW480 and DLD-1 cells and their proliferation (DLD-1 only), migration, and invasion. Over-expression of miR-21 promoted tumor growth in BALB/c nude mice and suppressed tumor expression of Sec23A.

Conclusion

These findings provide novel insight into the molecular functions of miR-21 in CRC, which may serve as a potential interesting target.

MicroRNA-21 promotes phosphatase gene and protein kinase B/phosphatidylinositol 3-kinase expression in colorectal cancer

AIM: To explore the regulatory mechanism of the target gene of microRNA-21 (miR-21), phosphatase gene (PTEN), and its downstream proteins, protein kinase B (AKT) and phosphatidylinositol 3-kinase (PI3K), in colorectal cancer (CRC) cells.

METHODS: Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression levels of miR-21 and PTEN in HCT116, HT29, Colo32 and SW480 CRC cell lines. Also, the expression levels of PTEN mRNA and its downstream proteins AKT and PI3K in HCT116 cells after downregulating miR-21 were investigated.

RESULTS: Comparing the miR-21 expression in CRC cells, the expression levels of miR-21 were highest in HCT116 cells, and the expression levels of miR-21 were lowest in SW480 cells. In comparing miR-21 and PTEN expression in CRC cells, we found that the protein expression levels of miR-21 and PTEN were inversely correlated (P < 0.05); when miR-21 expression was reduced, mRNA expression levels of PTEN did not significantly change (P > 0.05), but the expression levels of its protein significantly increased (P < 0.05). In comparing the levels of PTEN protein and downstream AKT and PI3K in HCT116 cells after downregulation of miR-21 expression, the levels of AKT and PI3K protein expression significantly decreased (P < 0.05).

CONCLUSION: PTEN is one of the direct target genes of miR-21. Thus, phosphatase gene and its downstream AKT and PI3K expression levels can be regulated by regulating the expression levels of miR-21, which in turn regulates the development of CRC.

MicroRNAs: Novel immunotherapeutic targets in colorectal carcinoma

Colorectal carcinoma (CRC) is one of the most common types of cancer worldwide and the prognosis for CRC patients with recurrence or metastasis is extremely poor. Although chemotherapy and radiation therapy can improve survival, there are still numerous efforts to be performed. Immunotherapy is frequently used, either alone or in combination with other therapies, for the treatment of CRC and is a safe and feasible way to improve CRC treatment. Furthermore, the significance of the immune system in the biology of CRC has been demonstrated by retrospective assessments of immune infiltrates in resected CRC tumors. MicroRNAs (miRNAs) are short, non-coding RNAs that can regulate multiple target genes at the post-transcriptional level and play critical roles in cell proliferation, differentiation and apoptosis. MiRNAs are required for normal immune system development and function. Nevertheless, aberrant expression of miRNAs is often observed in various tumor types and leads to immune disorders or immune evasion. The immunomodulatory function of miRNAs indicates that miRNAs may ultimately be part of the portfolio of anti-cancer targets. Herein, we will review the potential roles of miRNAs in the regulation of the immune response in CRC and then move on to discuss how to utilize different miRNA targets to treat CRC. We also provide an overview of the major limitations and challenges of using miRNAs as immunotherapeutic targets.

Tissue microRNA-21 expression predicted recurrence and poor survival in patients with colorectal cancer - a meta-analysis

OBJECTIVE

MicroRNA-21 (miR-21) has been shown to play an important role in cancer prognosis. We performed a meta-analysis to evaluate the prognostic effect of miR-21 from tissues and serum on survival of the patients with colorectal cancer (CRC).

METHODS

Relevant studies were identified by searching PubMed, Embase, and Cochrane Library. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) of total and subgroup analyses, for overall survival (OS) and disease-free survival (DFS), were calculated to investigate the association between miR-21 expression and CRC prognosis.

RESULTS

Our analysis included eleven studies (3,669 subjects). In addition, four studies explored the association between miR-21 and DFS, and ten studies focused on the prognostic value of miR-21 for OS. Our results indicated that increased miR-21 expression of tissues predicted both poor DFS and OS in patients with CRC (DFS: HR =1.59, 95% CI =1.20-2.10; OS: HR =1.53, 95% CI =1.23-1.90). Consistent results were observed among colon cancer and quantitative real-time polymerase chain reaction subgroups.

CONCLUSION

Meta-analysis indicated that miR-21 predicted recurrence and poor survival in patients with CRC. miR-21 may be more suitable to predict cancer prognosis in colon cancer patients.