MicroRNAs in colorectal cancer as markers and targets: Recent advances

Genome-Wide Analysis of microRNA and mRNA Expression in Colorectal Intramucosal Neoplasia and Colorectal Cancer With a Microsatellite-Stable Phenotype Based on Adenoma-Carcinoma Sequences

Background

Although MicroRNAs (miRNAs) play important roles in various biological processes, the biological functions of miRNAs are achieved through mRNAs. The aim of this study is to identify dysregulated miRNA/mRNA expression patterns in colorectal tumors.

Methods

We examined 42 colorectal tumors [15 adenomas, 8 intramucosal cancers (IMCs), and 19 invasive colorectal cancers (CRCs)] with the microsatellite stable (MSS) phenotype (first cohort). The first cohort was used for genome-wide miRNA and mRNA expression arrays, whereas the second cohort (37 colorectal neoplasias) was used for validation analyses. Finally, we used 15 cases of “adenoma in/with carcinoma” to identify network patterns of miRNAs/mRNAs that were directly associated with neoplastic progression. In addition, simple regression analysis for array-based and RT-PCR analyses was performed to select candidate miRNA–mRNA pairs. Transfection of miRNA mimics was also performed to confirm whether target mRNA expression is affected by specific miRNAs.

Results

Specific paired miRNA/mRNA networks, including hsa-miR-34a-5p/SLC12A2, hsa-miR-15b-5p/SLC12A2, hsa-miR-195-5p/SLC12A2, hsa-miRNA-502-3p/OLFM4, hsa-miRNA-6807-5p/ZG16, and hsa-miRNA 3064-5p/SH3BGRL3, were identified in samples of adenoma, IMC, and CRC with the MSS phenotype. In adenomatous lesions obtained from the same tumor with a carcinomatous lesion, we identified pairs of miRNA-130a-3p/HSPA8 and miRNA-22-3p/RP53 that were linked to multiple pathways. On the other hand, 2 pairs of miRNA/mRNA (miRNA-660-5p and miRNA-664a-5p/APP) were found in isolated carcinomatous glands. Ectopic expression of miRNA 3064-5p suppressed SH3BGRL3 expression.

Conclusions

We found that networks based on specific pairs of miRNAs/mRNAs contribute to progression from adenomatous and carcinomatous lesions. Our results provide insights into the molecular tumorigenesis of colorectal tumors.

Comprehensive analyses of microRNA and mRNA expression in colorectal serrated lesions and colorectal cancer with a microsatellite instability phenotype

MicroRNA (miRNA) expression is dysregulated in human tumors, thereby contributing to tumorigenesis through altered expression of mRNA. Thus, identification of the relationships between miRNAs and mRNAs is important for evaluating the molecular mechanisms of tumors. In addition, elucidation of the molecular features of serrated lesions is essential in colorectal tumorigenesis. Here, we examined the relationships of miRNA and mRNA expressed in serrated lesions, including 26 sessile serrated lesions (SSLs), 12 traditional serrated adenomas (TSAs), and 11 colorectal cancers (CRCs) with a microsatellite instability (MSI) phenotype using crypt isolation. We divided the samples into the first and second cohorts for validation. Array-based expression analyses were used to evaluate miRNAs and mRNAs with opposite expression patterns in isolated tumor glands. In addition, we validated the relationships of miRNA/mRNA pairs in the second cohort using real-time polymerase chain reaction. We found that the expression of miRNA-5787 was correlated with reciprocal expression of two mRNAs, that is, SRRM2 and POLR2J3, in SSL samples. In TSA samples, two pairs of miRNAs/mRNAs showing opposite expression patterns, that is, miRNA-182-5p/ETF1 and miRNA-200b-3p/MYB, were identified. Ultimately, three pairs of miRNAs/mRNAs with opposite expression patterns, including miRNA-222-3p/SLC26A3, miRNA-6753-3p/FABP1, and miRNA-222-3p/OLFM4, were retained in CRC with an MSI phenotype. Finally, we performed transfection with an miR-222-3p mimic to confirm the expression of SLC26A3 and OLFM4; the results showed that ectopic expression of miR-222-3p moderately suppressed OLFM4 and downregulated SLC26A3 to some extent. Overall, our results provided basic insights into the evaluation of colorectal tumorigenesis of serrated lesions and CRC with an MSI phenotype.

Hsa-miR-186-5p regulates TGFβ signaling pathway through expression suppression of SMAD6 and SMAD7 genes in colorectal cancer

TGFβ signaling is a known pathway to be involved in colorectal cancer (CRC) progression and miRNAs play crucial roles by regulating different components of this pathway. Hence, finding the link between miRNAs and the pathway could be beneficial for CRC therapy. Array data indicated that miR-186-5p is a differentially expressed miRNA in colorectal Tumor/Normal tissues and bioinformatics tools predicted SMAD6/7 (inhibitory SMADs) as bona fide targets of this miRNA. Here, we intended to investigate the regulatory effect of the miR-186-5p expression on TGFβ signaling in CRC. Firstly, the miR-186-5p overexpression in HCT116 cells resulted in a significant reduction of SMAD6/7 expression, measured through RT-qPCR. Then, the direct interactions of miR-186-5p with SMAD6/7 3'UTRs were supported through dual luciferase assay. Furthermore, miR-186-5p overexpression suppressed proliferation, cell viability, and migration while, it increased apoptosis in CRC cells, assessed by cell cycle, MTT, scratch and Annexin V/PI apoptosis assays. Consistently, miR-186-5p overexpression resulted in reduced CyclinD1 protein using western blot, and also resulted in increased P21 and decreased c-Myc expression. Overall, these results introduced miR-186-5p as a cell cycle suppressor through downregulation of SMAD6/7 expression. Thus, miR-186-5p might be served as a novel tumor suppressive biomarker and therapeutic target in CRC treatment.

MicroRNA Expression and Correlation with mRNA Levels of Colorectal Cancer-Related Genes

INTRODUCTION

MicroRNAs (miRNAs), as a family of non-coding RNAs, have opened a new window in cancer biology and transcriptome. It has been revealed that miRNAs post-transcriptionally regulate the gene expression and involve in colorectal cancer (CRC) development and progression. Our aim was to examine the differential expression of miRNAs in a CRC and to correlate their expression levels with mRNA levels of CRC-related genes (K-ras, APC, p53).

MATERIALS AND METHODS

Seventy-two colorectal tumor tissues from patients with newly diagnosed CRC and 72 matched normal adjacent tissues were analyzed. Relative expression of seven CRC-related miRNAs (miR-21, miR-31, miR-20a, miR-133b, and miR-145, miR-135b and let-7g) and three CRC-related genes (K-ras, APC, p53) was detected using the SYBR Green quantitative real-time PCR technique. The correlation between gene expression levels and clinicopathological features was evaluated.

RESULTS

Our results showed a significant difference between the two groups for the expression level of miR-21, miR-31, miR-145, and miR-20a (P < 0.001). Also, a significant difference between the two groups for the expression level of K-ras was found (P < 0.001). Further analysis revealed an inverse significant correlation between miR-145 and K-ras (R² = 0.662, P < 0.001), while a positive correlation was observed between miR-21 and K-ras (R² = 0.732, P < 0.001).

CONCLUSION

Dysregulation of miRNAs and correlation with molecular signaling pathways designated a biological role for miRNAs in various cellular mechanisms underlying CRC. On the other hand, the pattern of miRNAs expression and its correlation with transcriptional status are helpful to discovery biomarkers and design therapeutics for CRC.

RFC2, a direct target of miR-744, modulates the cell cycle and promotes the proliferation of CRC cells

Colorectal cancer (CRC) is a common digestive tract malignancy, which is characterized by high mortality, morbidity, and poor prognosis. Replication factor C subunit 2 (RFC2), one RFC family member, was reported to be related to various malignancies and plays an important role in proliferation, invasion, and metastasis. Nonetheless, the RFC2 biological role within CRC is still unknown. RFC2 expression profiles in CRC tissues were collected based on The Cancer Genome Atlas database, whereas miR-744 and RFC2 expression levels were detected in human CRC tissues. miR-744 and RFC2 effects on the proliferation of CRC were assessed both in vivo and in vitro. RFC2 was recognized to be a direct miR-744 target through luciferase reporter assay. RFC2 upregulation was observed within CRC tissues, and a high RFC2 level showed a correlation with poor clinicopathological symptoms. RFC2 knockdown inhibited CRC cell proliferation through promoting cell cycle arrest at the G1 phase, which was achieved by cyclin E2 (CCNE2) downregulation in vivo and in vitro. miR-744 was identified to be the tumor suppressor microRNA, which targeted RFC2 directly for inhibiting the proliferation of CRC cells both in vivo and in vitro. miR-744 downregulation was detected within CRC tissue, and messenger RNA expression showed a negative correlation with RFC2 expression within CRC tissues. Our study demonstrates that the miR-744/RFC2/CCNE2 axis potentially provides a candidate for a treatment strategy for CRC.

Cyto-biological effects of microRNA-424-5p on human colorectal cancer cells

MicroRNA (miR)-424-5p is overexpressed in colorectal cancer (CRC); however, its role, clinical significance and underlying molecular mechanism have remained to be fully elucidated. The aim of the present study was to investigate the roles of miR-424-5p in CRC and the underlying mechanisms. It was demonstrated that miR-424-5p is overexpressed in CRC, based on bioinformatics analysis using The Cancer Genome Atlas TCGA and analysis of tissue samples from patients with CRC from The First Hospital of Hebei Medical University, and the expression of miR-424-5p was associated with the depth of invasion and Dukes' staging. In CRC cells, the oncogenic roles of miR-424-5p were also verified by Cell Counting Kit-8, wound healing and Transwell assays. To identify target genes, all transcripts were compared between miR-424-5p mimic-transfected SW480 cells and mimic control cells by transcriptome sequencing. Subsequently, the differentially expressed genes (DEGs) were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. The DEGs were revealed to be significantly enriched in the GO terms 'serine hydrolase activity,' 'serine-type peptidase activity' and 'serine-type endopeptidase activity'. KEGG signaling pathway analysis indicated that the DEGs were significantly enriched in 'endocytosis', 'regulation of actin cytoskeleton', 'Wnt signaling pathway' and 'ubiquitin-mediated proteolysis signaling pathway'. These results suggested that miR-424-5p is a potential target in the treatment of CRC.

The association of a single-nucleotide variant in the microRNA-146a with advanced colorectal cancer prognosis

The aim of this study was to evaluate the association of single-nucleotide variant n.60G>C (rs2910164) of microRNA (miR)-146a, related to suppressing of BRCA1/2 DNA repair protein, with the risk and survival of colorectal cancer patients, as well as miR-146a and BRCA1/2 levels and miR binding efficiency. The genotypes were identified in 125 colorectal cancer patients and 276 controls using TaqMan polymerase chain reaction assay. The miR-146a and BRCA1/2 levels were assessed by quantitative-polymerase chain reaction protocols. Primary precursor of miR-146a containing G (wild-type) and C (variant) allele were cloned into pcDNA.3.3 vector and co-transfected in HT-29 colorectal cancer cell line. Luciferase reporter assay was performed to assess miR-146a binding to BRCA2 3'-untranslated region in HT-29. The differences between groups were calculated using chi-square or Fisher's exact test, logistic regression, and Mann-Whitney test. The prognostic impact of single-nucleotide variant genotypes on overall survival was evaluated by Kaplan-Meier estimate and Cox regression. The GC or CC genotypes prevalence was similar in patients and controls (50.4% vs 50.7%, p = 0.74). However, patients with tumors in advanced stage with miR-146a GG genotype had 2.41 more chance of dying than GC or CC genotypes. In addition, tumor tissues of patients with GG genotype presented higher miR-146a (p = 0.02) and lower BRCA1 (p = 0.01) and BRCA2 (p < 0.0001) levels when compared to those with GC or CC genotypes. In fact, pcDNA.3.3-miR-146a-G presented increased binding capacity to the 3'-untranslated region of BRCA2 (p = 0.001) compared to pcDNA.3.3-miR-146a-C. In addition, the G allele altered the binding affinity between miR-146a and its BRCA2 3'-untranslated region target (p < 0.001), thus enhancing suppression of BRCA2 expression. Our results suggest that single-nucleotide variant rs2910164 does not influence the colorectal cancer risk in Brazilian patients; however, the GG genotype could act as a factor of worse prognosis in patients with advanced disease due to suppression of BRCA1/2 modulated by miR-146a.

MiR-153-5p promotes sensibility of colorectal cancer cells to oxaliplatin via targeting Bcl-2-mediated autophagy pathway

Oxaliplatin (L-OHP) is one of the effective chemotherapeutic drugs for colorectal cancer (CRC). Further investigation into the molecular mechanism of chemoresistance could improve outcomes for patients with colorectal cancer. Recently, microRNAs have been reported as a key in drug resistance of tumors. In this study, we aimed to investigate the effects of miR-153-5p in L-OHP-resistant CRC cells, and its underlying mechanism. Downregulation of miR-153-5p was observed in CRC cells, while upregulation of miR-153-5p enhances the chemosensitivity of CRC/L-OHP cells. The autophagy of CRC/L-OHP cells was markedly increased after exposure to L-OHP but abolished by the upregulation of miR-153-5p. Dual-luciferase reporter assays validated that Bcl-2 was a direct target of miR-153-5p. In conclusion, our data suggested that miR-153-5p was a mediator of cisplatin resistance in colorectal cancer by affecting Bcl-2-mediated autophagy, indicating a new therapeutic target for CRC treatment.

microRNA-93, upregulated in serum of nasopharyngeal carcinoma patients, promotes tumor cell proliferation by targeting PDCD4

Deregulation of microRNAs (miRs) has been demonstrated to contribute to the development and malignant progression of nasopharyngeal carcinoma (NPC). Recently, miR-93 was reported to be significantly upregulated in NPC tissues and cell lines, and promote the proliferation, migration and invasion of NPC cells in vitro, as well as tumor growth in vivo. However, whether there is any clinical value of serum miR-93 expression in NPC still remains unclear. Therefore, the present study aimed to explore the clinical significance of serum miR-93 expression in NPC. A total of 85 serum samples from NPC patients and 30 from healthy controls were collected. Reverse transcription-quantitative polymerase chain reaction data demonstrated that the serum expression of miR-93 was significantly increased in NPC patients, when compared with those in healthy controls. Following receiving chemo-radiotherapy, the serum miR-93 levels were significantly decreased in NPC patients. Furthermore, the increased serum levels of miR-93 were significantly associated with advanced grade, clinical stage, lymph node metastasis, as well as worse 5-year overall survival of NPC patients. Furthermore, the serum miR-93 expression was demonstrated to be an independent factor for predicating the prognosis of NPC. In vitro experiments demonstrated that knockdown of miR-93 caused a decrease in NPC cell proliferation, whereas overexpression of miR-93 promoted NPC cell proliferation. PDCD4 was then identified as a direct target of miR-93 in NPC cells. Overexpression of PDCD4 significantly eliminated the promoting effects of miR-93 overexpression on NPC cell proliferation. Taken together, these findings suggest that the serum miR-93 expression could be used as a predicator for the clinical outcome of NPC patients, and suggest that miR-93 may also become a potential therapeutic target for NPC treatment.

miR-137 alleviates focal cerebral ischemic injury in rats by regulating JAK1/STAT1 signaling pathway

The repairing effect and potential mechanism of miR-137 on cerebral ischemic injury in rats was investigated. The volume of cerebral infarction and calculated brain water content was detected by triphenyltetrazolium chloride staining. The expression of inflammatory factors was detected by enzyme-linked immunosorbent assay. The pathological damage of brain tissue was analyzed by hematoxylin and eosin and Nissl staining. The apoptosis in ischemic brain tissue was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling. The levels of STAT1 and JAK1 proteins were analyzed by Western blot. The expression of miR-137 in primary hippocampal neurons was detected by reverse transcription polymerase chain reaction. miR-137 overexpression significantly improved brain damage in rats. miR-137 overexpression can reduce the expression of TNF-α, IL-1β, and IL-6. miR-137 overexpression can reduce the degree of brain tissue damage and inhibit the expression of JAK1 and STAT1 proteins. miR-137 overexpression can reduce oxygen-glucose deprivation (OGD)/R-induced cell damage, improve cell proliferation, and reduce apoptotic rate. JAK1 and STAT1 protein expression was inhibited in hippocampal neurons after OGD/R treatment after transfection with miR-137 mimic. After the addition of the Filgotinib inhibitor, the levels of JAK1 and STAT1 proteins were significantly reduced. The results suggested that miR-137 overexpression can effectively improve ischemic injury after focal cerebral ischemia and protect against by inhibiting JAK1/STAT1 pathway.

FOXC1 Regulation of miR-31-5p Confers Oxaliplatin Resistance by Targeting LATS2 in Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer-related illness worldwide and one of the most common malignancies. Therefore, colorectal cancer research and cases have gained increasing attention. Oxaliplatin (OXA) is currently used in first-line chemotherapy to treat stage III and stage IV metastatic CRC. However, patients undergoing chemotherapy often develop resistance to chemo drugs being used. Evidence has confirmed that microRNAs regulate downstream genes in cancer biology and thereby have roles related to tumor growth, proliferation, invasion, angiogenesis, and multi-drug resistance. The aim of our study is to establish whether miR-31-5p is an oncogene in human colorectal cancers that are resistant to OXA and further confirm its malignant phenotype-associated target molecule. From the results of miRNA microarray assay, we establish that miR-31-5p expression was upregulated in oxaliplatin-resistant (OR)-LoVo cells compared with parental LoVo cells. Moreover, through in vitro and in vivo experiments, we demonstrate that miR-31-5p and large tumor suppressor kinase 2 (LATS2) were inversely related and that miR-31-5p and Forkhead box C1 (FOXC1) were positively correlated in the same LoVo or OR-LoVo cells. Importantly, we reveal a novel drug-resistance mechanism in which the transcription factor FOXC1 binds to the miR-31 promoter to increase the expression of miR31-5p and regulate LATS2 expression, resulting in cancer cell resistance to OXA. These results suggest that miR-31-5p may be a novel biomarker involved in drug resistance progression in CRC patients. Moreover, the FOXC1/miR31-5p/LATS2 drug-resistance mechanism provides new treatment strategies for CRC in clinical trials.

Effect and mechanism of microRNA-10b on proliferation and invasion of esophageal cancer cells

MicroRNA (miR)-10b is highly expressed in esophageal cancer tissues and is associated with poor prognosis of esophageal cancer. However, the role and mechanism of miR-10b in esophageal cancer cells remains unclear, therefore, the present study aimed to investigate this. Esophageal cancer cells, TE-1 and EC9706, were transfected with miR-10b mimic, miR-10b inhibitor or incubated with transforming growth factor-β (TGF-β). MTT and EdU assays were used to detect cell proliferation. Flow cytometry was used to determine cell cycle analysis and apoptosis. Cell migration and invasion were also analyzed. Western blot analysis was used to detect protein levels and reverse transcription-quantitative PCR was used to analyze miR-10b expression. The present results demonstrated that, compared with the control group, miR-10b significantly promoted TE-1 and EC9706 cell proliferation. Compared with miR-10b inhibitor group and control group, miR-10b mimic promoted esophageal cancer cell cycle progression, inhibited apoptosis of esophageal cancer cells and promoted the migration and invasion of cells. The proliferation of esophageal cancer cells increased in a dose-dependent manner with TGF-β concentration. TGF-β treatment induced high expression of miR-10b in both cell lines. The miR-10b mimic + TGF-β group further promoted the migration and invasion of esophageal cancer cells. Western blot analysis determined that, compared with the control group, miR-10b mimic increased TGF-β expression. miR-10b mimic also inhibited the expression of phosphatase and tensin homolog (PTEN) in tumor cells. Compared with the control group, TGF-β inhibited the expression of PTEN with the miR-10b mimic + TGF-β group further inhibiting the PTEN. miR-10b inhibitor + TGF-β reversed the effect of TGF-β and miR-10b on PTEN. In conclusion, miR-10b promoted cell cycle progression, inhibited apoptosis and promoted the migration and invasion of esophageal cancer cells. The mechanism may be related to the upregulation of TGF-β and the downregulation of PTEN. The present findings suggested that miR-10b might be a potential therapeutic target for esophageal cancer.

MicroRNA and mRNA Interaction Network Regulates the Malignant Transformation of Human Bronchial Epithelial Cells Induced by Cigarette Smoke

This study analyzes the correlation and interaction of miRNAs and mRNAs and their biological function in the malignant transformation of BEAS-2B cells induced by cigarette smoke (CS). Normal human bronchial epithelial cells (BEAS-2B) were continuously exposed to CS for 30 passages (S30) to establish an in vitro cell model of malignant transformation. The transformed cells were validated by scratch wound healing assay, transwell migration assay, colony formation and tumorigenicity assay. The miRNA and mRNA sequencing analysis were performed to identify differentially expressed miRNAs (DEMs) and differentially expressed genes (DEGs) between normal BEAS-2B and S30 cells. The miRNA-seq data of lung cancer with corresponding clinical data obtained from TCGA was used to further identify lung cancer-related DEMs and their correlations with smoking history. The target genes of these DEMs were predicted using the miRDB database, and their functions were analyzed using the online tool “Metascape.” It was found that the migration ability, colony formation rate and tumorigenicity of S30 cells enhanced. A total of 42 miRNAs and 753 mRNAs were dysregulated in S30 cells. The change of expression of top five DEGs and DEMs were consistent with our sequencing results. Among these DEMs, eight miRNAs were found dysregulated in lung cancer tissues based on TCGA data. In these eight miRNAs, six of them including miR-96-5p, miR-93-5p, miR-106-5p, miR-190a-5p, miR-195-5p, and miR-1-3p, were found to be associated with smoking history. Several DEGs, including THBS1, FN1, PIK3R1, CSF1, CORO2B, and PREX1, were involved in many biological processes by enrichment analysis of miRNA and mRNA interaction. We identified the negatively regulated miRNA-mRNA pairs in the CS-induced lung cancer, which were implicated in several cancer-related (especially EMT-related) biological process and KEGG pathways in the malignant transformation progress of lung cells induced by CS. Our result demonstrated the dysregulation of miRNA-mRNA profiles in cigarette smoke-induced malignant transformed cells, suggesting that these miRNAs might contribute to cigarette smoke-induced lung cancer. These genes may serve as biomarkers for predicting lung cancer pathogenesis and progression. They can also be targets of novel anticancer drug development.

The Differential DNA Hypermethylation Patterns of microRNA-137 and microRNA-342 Locus in Early Colorectal Lesions and Tumours

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide, representing 13% of all cancers. The role of epigenetics in cancer diagnosis and prognosis is well established. MicroRNAs in particular influence numerous cancer associated processes including apoptosis, proliferation, differentiation, cell-cycle controls, migration/invasion and metabolism. MiRNAs-137 and 342 are exon- and intron-embedded, respectively, acting as tumour-suppressive microRNA via hypermethylation events. Levels of miRNAs 137 and 342 have been investigated here as potential prognostic markers for colorectal cancer patients. The methylation status of miRNA-137 and miRNA-342 was evaluated using methylation-specific (MSP) polymerase chain reaction (PCR) on freshly frozen tissue derived from 51 polyps, 8 tumours and 14 normal colon mucosa specimens. Methylation status of miRNA-137 and miRNA-342 was significantly higher in tumour lesions compared to normal adjacent mucosa. Surprisingly, the methylation frequency of miR-342 (76.3%) among colorectal cancer patients was significantly higher compared to miR-137 (18.6%). Furthermore, normal tissues, adjacent to the lesions (N-Cs), displayed no observable methylation for miRNA-137, whereas 27.2% of these N-Cs showed miRNA-342 hypermethylation. MiRNA-137 hypermethylation was significantly higher in male patients and miR-342 hypermethylation correlated with patient age. Methylation status of miRNA-137 and miRNA-342 has both diagnostic and prognostic value in CRC prediction and prevention.

Down-regulation of microRNA-144-3p and its clinical value in non-small cell lung cancer: a comprehensive analysis based on microarray, miRNA-sequencing, and quantitative real-time PCR data

BACKGROUND

Previous studies have shown that miR-144-3p might be a potential biomarker in non-small cell lung cancer (NSCLC). Nevertheless, the comprehensive mechanism behind the effects of miR-144-3p on the origin, differentiation, and apoptosis of NSCLC, as well as the relationship between miR-144-3p and clinical parameters, has been rarely reported.

METHODS

We investigated the correlations between miR-144-3p expression and clinical characteristics through data collected from Gene Expression Omnibus (GEO) microarrays, the relevant literature, The Cancer Genome Atlas (TCGA), and real-time quantitative real-time PCR (RT-qPCR) analyses to determine the clinical role of miR-144-3p in NSCLC. Furthermore, we investigated the biological function of miR-144-3p by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Protein-protein interaction (PPI) network was created to identify the hub genes.

RESULTS

From the comprehensive meta-analysis, the combined SMD of miR-144-3p was - 0.95 with 95% CI of (- 1.37, - 0.52), indicating that less miR-144-3p was expressed in the NSCLC tissue than in the normal tissue. MiR-144-3p expression was significantly correlated with stage, lymph node metastasis and vascular invasion (all P <  0.05). As for the bioinformatics analyses, a total of 37 genes were chosen as the potential targets of miR-144-3p in NSCLC. These promising target genes were highly enriched in various key pathways such as the protein digestion and absorption and the thyroid hormone signaling pathways. Additionally, PPI revealed five genes-C12orf5, CEP55, E2F8, STIL, and TOP2A-as hub genes with the threshold value of 6.

CONCLUSIONS

The current study validated that miR-144-3p was lowly expressed in NSCLC. More importantly, miR-144-3p might function as a latent tumor biomarker in the prognosis prediction for NSCLC. The results of bioinformatics analyses may present a new method for investigating the pathogenesis of NSCLC.

MiR-1260b inhibitor enhances the chemosensitivity of colorectal cancer cells to fluorouracil by targeting PDCD4/IGF1

Colorectal cancer (CRC) is the most common malignant tumor type and has become resistant to 5-fluorouracil (5-FU) in recent decades, which is one of the most popular therapies. Recently, microRNA (miRNA or miR) has been investigated as a potential therapeutic strategy for CRC. However, there has been little investigation of the underlying mechanism of the association between expression of miRNA and chemosensitivity. The present study aimed to investigate the effect of miR-1260b inhibitor on CRC cells, and their chemosensitivity to 5-FU, by treating them with the miR-1260b inhibitor. miR-1260b inhibitor was demonstrated to significantly promote the proliferation and invasion of the CRC cell line, HCT116, and to increase the apoptotic rate. Furthermore, it was validated that programmed cell death 4 (PDCD4) was a direct target of miR-1260b inhibitor in CRC with bioinformatics tools and a luciferase assay. Western blot analysis revealed that miR-1260b inhibitor could significantly decrease PDCD4 expression, and downregulate the expression of phosphorylated-Akt (p-Akt) and phosphorylated-extracellular-signal-regulated kinase (p-ERK). In conclusion, it was confirmed that the anti-tumor effect of the miR-1260b inhibitor was conducted by blocking the phosphorylated 3-kinase/Akt pathway as dysregulated protein expression induced by miR-1260b inhibitor was rescued by insulin-like growth factor. Notably, miR-1260b inhibitor could significantly enhanced the chemoresponse of HCT116 cells to 5-FU via reduced proliferation, increased apoptosis, and downregulation of PDCD4, p-Akt and p-ERK protein expression. In summary, the present study may provide a novel direction for future clinical therapy to enhance the chemosensitivity of tumor cells.

Inhibition of microRNA-21-3p suppresses proliferation as well as invasion and induces apoptosis by targeting RNA-binding protein with multiple splicing through Smad4/extra cellular signal-regulated protein kinase signalling pathway in human colorectal cancer HCT116 cells

MicroRNA-21-3p (miR-21-3p), the passenger strand of pre-mir-21, has been found to be high-expressing in various cancers and to be associated with tumour malignancy, which is proposed as a novel focus in malignant tumours. Colorectal cancer (CRC), currently known as one of the most prevalent malignancy, is a leading cause of cancer death. This study aimed to investigate the key role of miR-21-3p in CRC by inhibiting its expression using transfection with miR-21-3p inhibitors into human CRC HCT116 cells. Results showed that the expression of miR-21-3p was higher than other CRC cells used in the study including Lovo, HT29, Colo320 and SW480 cells, inhibition of which suppressed the proliferation and induced cell cycle arrest in HCT116 cells. Besides, transfection with miR-21-3p inhibitors also attenuated cell migration and invasion, and induced apoptosis as well. Moreover, luciferase assay confirmed RBPMS as a direct target of miR-21-3p in HCT116 cells. Further, miR-21-3p inhibitors increased the nuclear accumulation of Smad4 and reduced phosphorylation of ERK. Interestingly, we found that silence of RBPMS using RNA interference (siRNA) not only elevated the cell viability but also increased the phosphorylation of ERK and reversed the nuclear accumulation of Smad4 induced by miR-21-3p inhibitors in HCT116 cells. Data suggest that inhibition of miR-21-3p suppresses cell proliferation, invasion as well as migration and induces apoptosis by directly targeting RBPMS through Smad4/ERK signalling pathway in HCT116 cells. Our study demonstrates miR-21-3p as a potent target for suppressing tumour progression of CRC which may have implications in CRC therapy in the future.

Identification of a sixteen-microRNA signature as prognostic biomarker for stage II and III colon cancer

Despite advances in colon cancer research and novel therapies, high risk of recurrence remains a major challenge. This study reports miRNA expression profiling as a biomarker for the prognosis of TNM stage II and III colon cancer.

Fresh frozen biopsies from the study cohort (N=111) were analyzed for miRNA by RT-qPCR and LASSO regression analysis was used to build a classifier of miRNAs. The prognostic accuracy was tested and the classifier was validated in an independent colon cohort (TCGA-COAD, N=209).

The LASSO regression analysis identified a 16-miRNA signature including miR-143-5p, miR-27a-3p, miR-31-5p, miR-181a-5p, miR-30b-5p, miR-30d-5p, miR-146a-5p, miR-23a-3p, miR-150-5p, miR-210-3p, miR-25-3p, miR-196a-5p, miR-148a-3p, miR-222-3p, miR-30c-5p and miR-223-3p. A low 16-miRNA signature was associated with better 5-year disease-free survival (DFS) in the study cohort than a high signature (93 % versus 58 %; p< 0.001). The signature was an independent prognostic factor for better 5-year DFS in multivariate analyses (HR 21.4; 95% CI: 4.21-108.7; p< 0.001). The results in the validation cohort were consistent with the study cohort in univariate (77 % versus 65 %; p= 0.045) and multivariate analyses (HR 2.0; 95% CI: 1.04-3.89; p=0.039).

We identified a 16-miRNA signature as a reliable prognostic biomarker for classification of colon cancer stage II and III patients into groups with low and high risk for recurrence.

Identification of microRNAs involved in gefitinib resistance of non-small-cell lung cancer through the insulin-like growth factor receptor 1 signaling pathway

Multiple clinical and experimental studies have suggested that epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) may be effective at treating advanced non-small cell lung cancer (NSCLC), however, the molecular basis of primary resistance to EGFR-TKIs in NSCLC remains unclear. In the current study, the insulin-like growth factor 1 receptor (IGF-1R) gene in the gefitinib-resistant human lung adenocarcinoma epithelial cell line A549 (A549/GR) was silenced using small interfering RNA (siRNA) in order to determine the role of microRNA (miRNA) in the development of resistance against epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in lung adenocarcinoma. The relative gefitinib-resistant capacity in A549 and A549/GR cells was determined using a cell counting kit 8. A549/GR cells were transfected with chemically synthesized siRNA to silence the IGF-1R gene. A total of 48 h after siRNA transfection, IGF-1R expression in A549/GR cells was evaluated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting. miRNA expression in A549/GR cells and A549/GR cells with silenced IGF-1R was analyzed using a miRNA microarray. The microarray results of 10 miRNAs were then compared with the results of RT-qPCR. The results demonstrated that the gefitinib-resistance capacity of A549/GR cells was six times higher than that of A549 cells. Additionally, RT-qPCR and western blotting demonstrated that the IGF-1R gene in A549/GR cells was successfully silenced by siRNA. The highest silencing rate (72%) of the IGF-1R gene was obtained using siRNA-2. The microarray identified 72 miRNAs with significantly different expression in A549/GR cells with silenced IGF-1R compared with A549/GR cells. Of the 72 differentially expressed miRNAs, 13 miRNAs (including miR-497-3p and miR-1273c) were up-regulated and 59 miRNAs (including miR-361-3p and miR-345-3p) were down-regulated in A549/GR cells with silenced IGF-1R compared with A549/GR cells. The changes in the expression of 10 different miRNAs were confirmed by RT-qPCR. Thus, the present study successfully established an A549/GR cell line with silenced IGF-1R. The results suggest that a number of miRNAs associated with the IGF-1R signaling pathway, including miR-497-3p and miR-144-5p, were involved in the development of resistance against EGFR-TKIs in A549 cells. These miRNAs may provide novel targets to treat lung adenocarcinoma exhibiting resistance against EGFR-TKIs.

MicroRNA-92a promotes cell viability and invasion in cervical cancer via directly targeting Dickkopf-related protein 3

MicroRNA-92a (miR-92a) was recently reported to have an oncogenic role in cervical cancer; however, the underlying mechanism remains largely unclear. The present study aimed to investigate the expression, clinical significance and regulatory mechanism of miR-92a in cervical cancer. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) data indicated that miR-92a was significantly upregulated in cervical cancer tissues compared with matched adjacent non-tumor tissues (P<0.01). High expression of miR-92a was significantly associated with poor differentiation (P=0.031), advanced clinical stage (P=0.011) and lymph node metastasis (P=0.014), but not associated with age, tumor size and distant metastasis. Knockdown of miR-92a significantly inhibited the viability and invasion of cervical cancer HeLa cells, while overexpression of miR-92a significantly enhanced HeLa cell viability and invasion (P<0.01). Luciferase reporter assay identified Dickkopf-related protein 3 (DKK3) as a target gene of miR-92a, and the protein expression of DKK3 was negatively regulated by miR-92a in HeLa cells. Furthermore, overexpression of DKK3 significantly eliminated the stimulative effects of miR-92a on HeLa cell viability and invasion (P<0.01). Additionally, DKK3 was significantly downregulated in cervical cancer tissues compared with adjacent non-tumor tissues (P<0.01), inversely correlated to the miR-92a levels in cervical cancer tissues (P<0.01). In summary, the present study indicated that miR-92a promotes cell viability and invasion in cervical cancer, partly at least, via inhibiting the protein expression of DKK3. Therefore, the present study highlights the clinical significance of the miR-92a/DKK3 axis in cervical cancer.

Biological effects and clinical characteristics of microRNA-106a in human colorectal cancer

MicroRNAs serve important roles in various diseases, particularly cancer. microRNA-106a (miR-106a) exhibits abnormal expression and oncogenic activity in carcinogenesis. The clinical significance of the abnormal expression of miR-106a in colorectal cancer is poorly understood. In the present study, miR-106a expression from colorectal cancer tissues was quantified using the reverse transcription-quantitative polymerase chain reaction. The overexpression or knockdown of miR-106a was performed by transfection with microRNA mimic or inhibitor in human colorectal carcinoma HCT116 cells. The overexpression of miR-106a promoted viability and inhibited apoptosis in colorectal cancer cells. The association between miR-106a expression and clinicopathological factors was analyzed, and it was identified that miR-106a exhibited significantly increased expression in adenocarcinoma tissues compared with in mucinous carcinoma tissues, and the expression of miR-106a was identified to be associated with the depth of invasion and differentiation. The expression of miR-106a in plasma was also determined and it was identified that increased expression of miR-106a, as a characteristic of patients with colorectal cancer, may be distinguished from that of other patients by digitization of the areas under the receiver operating characteristic curves. These data suggested that miR-106a is a potential biomarker in the diagnosis of colorectal carcinoma. However, the underlying molecular mechanism of miR-106a-promoted viability and inhibition of apoptosis requires further investigation.

The trophoblast cell surface antigen 2 and miR-125b axis in urothelial bladder cancer

Human trophoblast cell surface antigen 2 (Trop-2) is a 40-kDa transmembrane glycoprotein that was first identified as a marker of human trophoblast cells. Trop-2 acts on cell proliferation, adhesion, and migration by activating a number of intracellular signalling pathways. Elevated Trop-2 expression has been demonstrated in several types of cancer and correlated with aggressiveness and poor prognosis. Since no data are available on Trop-2 in bladder cancer (BC), the purpose of the study was to determine its levels in tissue specimens from normal individuals and patients with BC at different stages. Moreover, since according to recent evidence Trop-2 is a miR-125b target, miR-125b expression was also assessed in tissue specimens. Finally, the effect of the Trop-2/miR-125b axis on the proliferation and migration of BC cells was evaluated in vitro.

The Trop-2/miR-125b axis was seen to be differentially expressed in normal urothelium, non-invasive BC and invasive BC tissue. Significant miR-125b down-regulation was associated with a significant increase in Trop-2 protein levels in BC tissue and correlated with disease severity. In vitro analysis confirmed the role of miR-125b in down-modulation of Trop-2 protein levels and showed that Trop-2/miR-125b axis affects cellular proliferation in bladder tissue.

In conclusion, our findings highlight a role for the Trop-2/miR-125b axis in BC progression and suggest Trop-2 and miR-125b as diagnostic/prognostic marker candidates as well as druggable targets for innovative therapeutic approaches.

MicroRNA-17-5p inhibits proliferation and triggers apoptosis in non-small cell lung cancer by targeting transforming growth factor β receptor 2

MicroRNAs (miRs) are small non-coding RNAs that suppress gene expression by directly binding to the 3′-untranslated region of their target mRNAs. Specific miRs serve key roles in the development and progression of non-small cell lung cancer (NSCLC). The aim of the present study was to determine the mechanism of miR-17-5p in the regulation of NSCLC cell survival and proliferation. Reverse transcription-quantitative polymerase chain reaction data indicated that miR-17-5p was significantly downregulated in 28 NSCLC tissues compared with 7 non-tumorous lung tissues. Furthermore, lower miR-17-5p expression was associated with a higher pathological stage in NSCLC patients. Lower miR-17-5p expression was also observed in several common NSCLC cell lines, including SK-MES-1, A549, SPCA-1, H460, H1229 and HCC827, compared with the bronchial epithelium cell line, BEAS-2B. Additionally, overexpression of miR-17-5p significantly inhibited proliferation while inducing the apoptosis of NSCLC H460 cells. Subsequently, transforming growth factor β receptor 2 (TGFβR2) was identified as a direct target of miR-17-5p using a luciferase reporter assay. Western blot analysis confirmed that miR-17-5p negatively mediated the expression of TGFβR2 in NSCLC cells. Furthermore, small interfering RNA-induced downregulation of TGFβR2 also suppressed the proliferation of H460 cells while triggering apoptosis. Therefore, the results of the current study suggest that miR-17-5p may inhibit proliferation and trigger apoptosis in NSCLC H460 cells at least partially by targeting TGFβR2.

CXCL12/CXCR4 axis induced miR-125b promotes invasion and confers 5-fluorouracil resistance through enhancing autophagy in colorectal cancer

The activation of CXCL12/CXCR4 axis is associated with potential progression of cancer, such as invasion, metastasis and chemoresistance. However, the underlying mechanisms of CXCL12/CXCR4 axis and cancer progression have been poorly explored. We hypothesized that miRNAs might be critical downstream mediators of CXCL12/CXCR4 axis involved in cancer invasion and chemoresistance in CRC. In human CRC cells, we found that the activation of CXCL12/CXCR4 axis promoted epithelial-mesenchymal transition (EMT) and concurrent upregulation of miR-125b. Overexpression of miR-125b robustly triggered EMT and cancer invasion, which in turn enhanced the expression of CXCR4. Importantly, the reciprocal positive feedback loop between CXCR4 and miR-125b further activated the Wnt/β-catenin signaling by targeting Adenomatous polyposis coli (APC) gene. There was a negative correlation of the expression of miR-125b with APC mRNA in paired human colorectal tissue specimens. Further experiments indicated a role of miR-125b in conferring 5-fluorouracil (5-FU) resistance in CRC probably through increasing autophagy both in vitro and in vivo. MiR-125b functions as an important downstream mediator upon the activation of CXCL12/CXCR4 axis that involved in EMT, invasion and 5-FU resistance of CRC. These findings shed a new insight into the role of miR-125b and provide a potential therapeutic target in CRC.

A network similarity integration method for predicting microRNA-disease associations

The NSIM integrates the disease similarity network, miRNA similarity network, and known miRNA-disease association network on the basis of cousin similarity to predict not only novel miRNA-disease associations but also isolated diseases.

miR-1260b is a Potential Prognostic Biomarker in Colorectal Cancer

Background

Colorectal cancer (CRC) mainly refers to colon and rectum cancer, which is the most common gastrointestinal malignant tumor. MicroRNAs (miRNAs) in tumors participate in multiple processes of malignancy development, including cell differentiation, proliferation, invasion, and metastasis. In this study we explored the relationship of miR-1260b abnormal expression with clinical pathological features in CRC patients.

Material/Methods

The expression of miR-1260b was detected by real-time quantitative polymerase chain reaction (real-time PCR) in 120 cases of CRC tissues. The correlation of miR-1260b expression with the clinicopathologic features of CRC was analyzed by SPSS 21.0 statistical software. The Kaplan-Meier method was used for survival analysis. Cox regression analyses were conducted to determine whether miR-1260b was an independent predictor of survival for CRC patients.

Results

The miR-1260b expression in CRC was significantly higher than the expression levels in the corresponding para-carcinoma tissues (P<0.001). According to the expression levels of miR-1260b, 120 cases of CRC patients were classified into either the miR-1260b high expression group or the miR-1260b low expression group. The high expression levels of miR-1260b in CRC patients was associated with lymph node metastasis (P<0.05) and venous invasion (P<0.001). However, the high miR-1260b expression had no significant correlation with other clinical parameters (P>0.05). The high miR-1260b expression patients survived for shorter times than those CRC patients with low miR-1260b expression (P<0.05). Multivariate analysis revealed that high miR-1260b means poor prognosis of patients with CRC.

Conclusions

The high expression level of miR-1260b is an independent prognostic biomarker that indicates a worse prognosis for patients with CRC.

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.

miRs-134 and -370 function as tumor suppressors in colorectal cancer by independently suppressing EGFR and PI3K signalling

Growth factor receptor signalling plays a central and critical role in colorectal cancer. Most importantly, the EGFR signalling cascade involving PI3K/AKT/mTOR and Raf/MEK/ERK pathways are particularly relevant, since they are commonly activated in several cancer entities, including colorectal cancer. In this study, we show that miRs-134 and -370 are both capable of regulating these pathways by targeting EGFR and PIK3CA. In three different colorectal cancer cell lines (DLD1, HCT-116 and RKO), suppression of EGFR and PIK3CA through the enhanced expression of miR-134 or -370 led to a suppression of the key molecules of the PI3K/AKT/mTOR pathway. Furthermore, overexpression of miR-134 or -370 resulted in a significant reduction of cell proliferation, colony formation, migration, invasion and in-vivo tumor growth and metastasis. Concurrent experiments with small interfering RNAs targeting the prime targets show that our selected miRNAs exert a greater functional influence and affect more downstream molecules than is seen with silencing of the individual proteins. Taken together, these data indicate that miRs-134 and -370 are potential tumour suppressor miRNAs and could play a fundamental role in suppressing colorectal cancer tumorigenesis through their ability to co-ordinately regulate EGFR signalling cascade by independently targeting EGFR and PIK3CA.

MicroRNAs expression in normal and malignant colon tissues as biomarkers of colorectal cancer and in response to pomegranate extracts consumption: Critical issues to discern between modulatory effects and potential artefacts

SCOPE

MicroRNAs (miRs) are proposed as colorectal cancer (CRC) biomarkers. Pomegranate ellagic acid and their microbiota metabolites urolithins exert anticancer effects in preclinical CRC models, and target normal and malignant colon tissues in CRC patients. Herein, we investigated whether the intake of pomegranate extract (PE) modified miRs expression in surgical colon tissues versus biopsies from CRC patients.

METHODS AND RESULTS

We conducted a randomized, double-blind, controlled trial. Thirty-five CRC patients consumed 900 mg PE daily before surgery. Control CRC patients (no PE intake, n = 10) were included. Our results revealed: (1) significant differences for specific miRs between malignant and normal tissues modifiable by the surgical protocols; (2) opposed trends between -5p and -3p isomolecules; (3) general induction of miRs attributable to the surgery; (4) moderate modulation of various miRs following the PE intake, and (5) no association between tissue urolithins and the observed miRs changes.

CONCLUSION

PE consumption appears to affect specific colon tissue miRs but surgery critically alters miRs levels hindering the discrimination of significant changes caused by dietary factors and the establishment of genuine differences between malignant and normal tissues as biomarkers. The components responsible for the PE effects and the clinical relevance of these observations deserve further research.

Fecal microRNA profile in patients with colorectal carcinoma before and after curative surgery

PURPOSE

The purpose of this study was to explore the potential role of deranged fecal microRNA (miRNA) pattern as a reliable warning signal of colorectal cancer (CRC), a subset of fecal CRC-related miRNAs was evaluated in CRC patients, before and after surgery, and in healthy controls.

METHODS

Twenty CRC patients and 20 age/sex-matched healthy volunteers with negative colonoscopy entered the study. Cancer biopsy, colonic mucosa from the resected specimens, and fecal samples from patients and controls were screened for 13 miRNAs involved in CRC onset and progressions by reverse transcription quantitative PCR (RT-qPCR). Postoperative evaluation of fecal miRNAs was carried out after a median follow-up of 18 months (range 12-30).

RESULTS

Two out 13 miRNAs (RNU6B, miR-16-3p) were used as internal controls leaving 11 available for analysis. Cancer tissue contained significantly higher expression of all miRNAs, compared to normal mucosa (p < 0.05). Expression of preoperative levels of five fecal miRNAs, (miR-19-b-3p, miR-20a-5p, miR-21-3p, miR92a-3p, miR141) was significantly higher in CRC patients compared to controls and significantly decreased after curative surgery. Three out of these five miRNAs (miR20a-5p, miR21-3p, and miR141) returned to values comparable to normal controls.

CONCLUSIONS

A set of three specific fecal miRNAs is overexpressed before surgery, and return within the normal range after cancer removal could be considered as an appealing opportunity for a new reliable tool for CRC secondary prevention. However, their role needs to be explored in large prospective trials and compared with the existing screening tools.

p53 mutations in colorectal cancer- molecular pathogenesis and pharmacological reactivation

Colorectal cancer (CRC) is one of the most common malignancies with high prevalence and low 5-year survival. CRC is a heterogeneous disease with a complex, genetic and biochemical background. It is now generally accepted that a few important intracellular signaling pathways, including Wnt/β-catenin signaling, Ras signaling, and p53 signaling are frequently dysregulated in CRC. Patients with mutant p53 gene are often resistant to current therapies, conferring poor prognosis. Tumor suppressor p53 protein is a transcription factor inducing cell cycle arrest, senescence, and apoptosis under cellular stress. Emerging evidence from laboratories and clinical trials shows that some small molecule inhibitors exert anti-cancer effect via reactivation and restoration of p53 function. In this review, we summarize the p53 function and characterize its mutations in CRC. The involvement of p53 mutations in pathogenesis of CRC and their clinical impacts will be highlighted. Moreover, we also describe the current achievements of using p53 modulators to reactivate this pathway in CRC, which may have great potential as novel anti-cancer therapy.

Up-regulation of miR-592 correlates with tumor progression and poor prognosis in patients with colorectal cancer

miR-592, as a potential biomarker, has been linked to several cancers. However, the expression level and prognostic value of miR-592 in CRC have not been elucidated. In this study, we detected the miR-592 expression in CRC serum, tumor tissues, adjacent non-tumor tissues (NATs) and four colorectal cancer cell lines by RT-PCR. Our data proved that miR-592 expression was up-regulated in clinical CRC serum and tissues (P<0.05). Serum or tissue miR-592 in CRC metastatic patients also maintained a high level, compared to that in non-metastatic CRC patients (P<0.05). After radical surgery, postoperative serum miR-592 level in CRC patients significantly decreased (P<0.05). Our clinicopathological analysis revealed that high miR-592 was significant associated with the tumor size (P=0.008), TNM stage (P=0.026), distant metastasis (P=0.004) and preoperative CEA level (P=0.022), which led to a shorter overall survival rate in CRC patients (P=0.032). Furthermore, we designed and transfected miR-592 mimics or inhibitors into the corresponding CRC lines, and our experiments in vitro demonstrated that miR-592 could promote cell proliferation, wound healing and invasion ability of CRC cells (P<0.05), while miR-592 did not influence the CRC cell apoptosis (P>0.05). All these results suggested that miR-592 functioned as a novel and potential carcinogen-initiated and metastasis-related biomarker in CRC, and down-regulation of miR-592 might be considered as a potentially significant molecular treatment strategy for CRC patients.

MicroRNA-133a suppresses colorectal cancer cell invasion by targeting Fascin1

MicroRNAs (miRs) are a type of small non-coding RNA molecule that are involved in gene silencing and the regulation of cancer progression; miR-133a in particular has been implicated in colorectal cancer, although its specific role and underlying mechanism have yet to be determined. In the present study, the expression level of miR-133a was significantly downregulated in a number of colorectal cancer cell lines, as well as in colorectal cancer tissues compared with the normal adjacent tissues. Furthermore, the Fascin1 (FSCN1) gene was identified as a direct target of miR-133a, and the protein expression level of FSCN1 was negatively regulated by miR-133a in colorectal cancer cells. Additionally, restoration of miR-133a expression and downregulation of FSCN1 protein expression suppressed colorectal cancer cell invasion, while overexpression of FSCN1 reversed the inhibitory effect of miR-133a upregulation on colorectal cancer cell invasion. Thus, the present data indicates that miR-133a may at least partially suppress colorectal cancer cell invasion, possibly via the inhibition of FSCN1 expression. The present study highlights the important role of miR-133a in the progression of colorectal cancer.

A miRNA-binding site single nucleotide polymorphism in the 3'-UTR region of the NOD2 gene is associated with colorectal cancer

Colorectal cancer (CRC) is one of the common malignancies worldwide. Single nucleotide polymorphisms in miRNA-binding site on gene transcripts are reported to play important role in increased risk of CRC in different population. We performed a case-control study using 88 CRC patients and 88 non-cancer counterparts to evaluate the association between NOD2 rs3135500 polymorphism located at 3' untranslated region of the gene and risk of sporadic CRC. Genotyping of rs3135500 polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. We found a significant association of AA genotype with risk of CRC (adjusted OR 3.100, CI 1.621-5.930, p < 0.001). Also, significant difference in physical activity (p = 0.001) between case and control groups was found. We also found that individuals in control group were more aspirin or NSAID user compared to sporadic CRC cases (p = 0.002). In the case group, individuals with GG genotype consumed more aspirin or NSAID compared with AA+AG genotypes (33.3 vs. 9.6 %, adjusted OR 4.71, CI 1.25-17.76, p = 0.02). However, in the control group, individuals with AA+AG genotypes used more aspirin or NSAID compared with GG genotypes (47.2 vs. 11.4 %, adjusted OR 14 %, CI 0.05-0.47, p < 0.001).

Lack of association between miR-27a, miR-146a, miR-196a-2, miR-492 and miR-608 gene polymorphisms and colorectal cancer

Colorectal cancer (CRC) is one of the most common cancers worldwide with high mortality rates. MicroRNAs (miRNAs) have an established role in the development of different cancers. Single nucleotide polymorphisms (SNPs) in miRNA related genes were linked with various gastrointestinal malignancies. However, the data on association between miRNA SNPs and CRC development are inconsistent. The aim of the present study was to evaluate the association between miRNA-related gene polymorphisms (miR-27a, miR-146a, miR-196a-2, miR-492 and miR-608) and the presence of CRC in European population. Gene polymorphisms were analyzed in 621 subjects (controls: n = 428; CRC: n = 193). MiR-27a T>C (rs895819), miR-146a G>C (rs2910164), miR-196a-2 C>T (rs11614913), miR-492 G>C (rs2289030) and miR-608 C>G (rs4919510) SNPs were genotyped by RT-PCR. Overall, all genotypes and alleles of miRNA SNPs were distributed equally between control and CRC groups. We observed a tendency for miR-146a C allele to be associated with lower risk of CRC when compared to G allele, however, the difference did not reach the adjusted P-value (odds ratio (OR) = 0.68, 95% confidence interval (CI) 0.49–0.95, P = 0.025). In conclusion, gene polymorphisms of miR-27a, miR-146a, miR-196a-2, miR-492, miR-492a and miR-608 were not associated with the presence of CRC in European subjects.

KITENIN-targeting microRNA-124 suppresses colorectal cancer cell motility and tumorigenesis

MicroRNAs are increasingly implicated in the modulation of the progression of various cancers. We previously observed that KAI1 C-terminal interacting tetraspanin (KITENIN) is highly expressed in sporadic human colorectal cancer (CRC) tissues and hence the functional KITENIN complex acts to promote progression of CRC. However, it remains unknown that microRNAs target KITENIN and whether KITENIN-targeting microRNAs modulate CRC cell motility and colorectal tumorigenesis. Here, through bioinformatic analyses and functional studies, we showed that miR-124, miR-27a, and miR-30b negatively regulate KITENIN expression and suppress the migration and invasion of several CRC cell lines via modulation of KITENIN expression. Through in vitro and in vivo induction of mature microRNAs using a tetracycline-inducible system, miR-124 was found to effectively inhibit the invasion of CT-26 colon adenocarcinoma cells and tumor growth in a syngeneic mouse xenograft model. Constitutive overexpression of precursor miR-124 in CT-26 cells suppressed in vivo tumorigenicity and resulted in decreased expression of KITENIN as well as that of MYH9 and SOX9, which are targets of miR-124. Thus, our findings identify that KITENIN-targeting miR-124, miR-27a, and miR-30b function as endogenous inhibitors of CRC cell motility and demonstrate that miR-124 among KITENIN-targeting microRNAs plays a suppressor role in colorectal tumorigenesis.