MicroRNAs in colorectal cancer metastasis

LncRNA CRLM1 inhibits apoptosis and promotes metastasis through transcriptional regulation cooperated with hnRNPK in colorectal cancer

Background

Colorectal liver metastases (CRLM) continue to have a low survival rate. The number of CRLM regulators and clinical indicators remains limited. Long non-coding RNAs (lncRNAs) are a new master regulator of cell invasion and metastasis. However, the function and regulation mechanism of lncRNAs in colorectal cancer (CRC) metastasis are yet unknown.

Methods

To screen and identify CRLM-related lncRNAs, public transcriptome data were used. Gain and loss of function experiments were carried out to investigate the biological activities of lncRNA CRLM1 in vitro and in vivo. RNA sequencing (RNA-seq), chromatin isolation by RNA purification (ChIRP), immunofluorescence (IF), quantitative real-time PCR (qRT-PCR), western blotting, and rescue experiments were performed to explore the molecular mechanism of CRLM1. Moreover, identified the proteins, DNAs, and RNAs that interact with CRLM1.

Results

The investigation of lncRNA expression dynamics in CRLM, primary CRC, and normal tissues in this work resulted in identifying a series of lncRNAs associated with metastasis, including CRLM1. CRLM1 inhibited apoptosis of CRC cells and promoted liver metastasis in Balb/C nude mice. CRLM1 was weakly associated with the chromatin regions of genes involved in cell adhesion and DNA damage, and this association was bidirectionally correlated with CRLM1-regulated pro-metastatic gene expression. CRLM1 physically interacts with the hnRNPK protein and promotes its nuclear localization. CRLM1 effectively enhances hnRNPK promoter occupancy and co-regulates the expression of a panel of metastatic genes.

Conclusions

The finding of the clinically significant lncRNA CRLM1 in promoting metastasis and regulating gene expression suggests a potential biomarker and target for CRLM therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00849-9.

Predictive models based on machine learning for bone metastasis in patients with diagnosed colorectal cancer

Background

This study aimed to develop an artificial intelligence predictive model for predicting the probability of developing BM in CRC patients.

Methods

From SEER database, 50,566 CRC patients were identified between January 2015 and December 2019 without missing data. SVM and LR models were trained and tested on the dataset. Accuracy, area under the curve (AUC), and IDI were used to evaluate and compare the models.

Results

For bone metastases in the entire cohort, SVM model with poly as kernel function presents the best performance, whose accuracy is 0.908, recall is 0.838, and AUC is 0.926, outperforming LR model. The top three most important factors affecting the model's prediction of BM include extraosseous metastases (EM), CEA, and size.

Conclusion

Our study developed an SVM model with poly as kernel function for predicting BM in CRC patients. SVM model could improve personalized clinical decision-making, help rationalize the bone metastasis screening process, and reduce the burden on healthcare systems and patients.

Ultrasound microbubble-mediated miR-503-5p downregulation suppressed in vitro CRC progression via promoting SALL1 expression

BACKGROUND

This study compared the effect of ultrasound microbubble-mediated miR-503-5p downregulation with that of pure liposome-mediated miR-503-5p downregulation on colorectal cancer (CRC) progression and explored the downstream mechanism.

METHODS

Bioinformatics tools were utilized to predict miR-503-5p-targeted genes and CRC progression-associated genes. MiR-503-5p and sal-like 1 (SALL1) expressions in CRC cells and tissues were analyzed by qRT-PCR and/or bioinformatics tools; their correlations with overall survival and clinicopathological features of CRC patients were presented, and their interaction was validated by dual-luciferase reporter assay. CRC cells received ultrasound microbubble-mediated miR-503-5p downregulation and/or liposome-mediated miR-503-5p downregulation or SALL1 silencing. Cell phenotype changes were evaluated by flow cytometry, as well as MTT, Wound healing, Transwell and tube formation assays. E-cadherin, N-cadherin, Vimentin, B-cell lymphoma (Bcl)- 2, Cleaved caspase-3, and SALL1 expressions in cells were analyzed by Western blot.

RESULTS

Upregulated miR-503-5p in CRC tissues and cells was detected, associated with poorer cell differentiation, easier lymph node metastasis and higher TNM stages, and related to poorer prognoses of CRC patients. Ultrasound microbubble-mediated miR-503-5p downregulation relative to pure liposome-mediated miR-503-5p downregulation better decreased viability, inhibited migration, invasion and tube formation, enhanced apoptosis, upregulated SALL1, E-cadherin and Cleaved caspase-3, and downregulated miR-503-5p, N-cadherin, Vimentin and Bcl-2 in CRC cells. SALL1 was targeted by miR-503-5p, low-expressed in CRC tissues and cells and positively related to CRC patients' survival. Silencing SALL1 exerted the opposite effects, which reversed the effects of ultrasound microbubble-mediated miR-503-5p downregulation and vice versa.

CONCLUSION

Ultrasound microbubble-mediated miR-503-5p downregulation suppressed in vitro CRC progression via promoting SALL1 expression.

MiR-20b-5p promotes hepatocellular carcinoma cell proliferation, migration and invasion by down-regulating CPEB3

INTRODUCTION AND OBJECTIVES

This study aimed to explore the functional mechanism of the miRNA-20b-5p/cytoplasmic polyadenylation element binding protein 3 (miR-20b-5p/CPEB3) axis in hepatocellular carcinoma (HCC) so as to provide a new idea for targeted therapy of HCC.

MATERIALS AND METHODS

Bioinformatics analysis was employed to obtain markedly differentially expressed miRNAs and mRNAs in The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC) dataset, so as to find target miRNA and its target mRNA. Real-time quantitative PCR was conducted to detect miR-20b-5p and CPEB3 mRNA expression. Western blot was performed to determine CPEB3 protein expression. Dual-luciferase reporter assay was carried out to verify the targeting relationship between miR-20b-5p and CPEB3. Cell counting kit-8 assay, wound healing assay, Transwell invasion assay and flow cytometry were conducted to evaluate the proliferation, migration, invasion and apoptosis of HCC cells.

RESULTS

Bioinformatics analysis suggested that miR-20b-5p and CPEB3 were markedly highly and lowly expressed, respectively, in HCC tissue in TCGA-LIHC dataset. Over-expressing miR-20b-5p facilitated the proliferation, migration and invasion, and suppressed the apoptosis of HCC cells. Dual-luciferase reporter assay validated that there was a targeting relationship between miR-20b-5p and CPEB3. The inhibitory effect of CPEB3 over-expression on HCC cell proliferation, migration and invasion was reversed by over-expressing miR-20b-5p.

CONCLUSIONS

The present study proved that miR-20b-5p promotes HCC cell proliferation, migration and invasion by inhibiting CPEB3 expression, which may provide a theoretical basis for the prognosis and treatment of HCC patients.

[Long non-coding RNA LINC01106 regulates colorectal cancer cell proliferation and apoptosis through the STAT3 pathway]

OBJECTIVE

To investigate the expression of LINC01106 in colorectal cancer and its role in regulating the proliferation and apoptosis of colorectal cancer cells.

METHODS

We analyzed the data of LINC01106 expression levels in tumor tissues and normal tissues of patients with colorectal cancer in TCGA database and explored the association of LINC01106 expression level with the prognosis of the patients. Colorectal cancer SW480 cell lines with LINC01106 knockdown or overexpression were established, and their proliferation and apoptosis relative to the parental cells were evaluated using CCK-8 assay and flow cytometry, respectively. The expressions of p-STAT3, STAT3, and Bcl-2 in the cells were detected by immunoblotting. Nude mouse models bearing xenografts of SW480 cells with LINC01106 knockdown or na?ve SW480 cells were established to observe the effect of LINC01106 knockdown on the growth of SW480 cells in vivo.

RESULTS

Analysis of the data from TCGA database showed that the expression level of LINC01106 was significantly higher in colorectal cancer tissues than in normal tissues, and LINC01106 expression level was significantly related to the prognosis of the patients (P < 0.05). Knockdown of LINC01106 significantly inhibited the proliferation and promoted apoptosis of SW480 cells (P < 0.05), while LINC01106 overexpression significantly promoted proliferation of the cells. LINC01106 knockdown in SW-480 cells obviously lowered the expressions of p- STAT3 and Bcl-2 and suppressed the growth of the xenograft in nude mice.

CONCLUSIONS

LINC01106 is significantly up-regulated in colorectal cancer tissue and is related to the prognosis of the patients. LINC01106 can regulate the proliferation and apoptosis of SW480 cells through STAT3/Bcl-2 signaling and may serve as a potential marker for the diagnosis and prognostic evaluation of colorectal cancer.

Antitumor effects of curcumin on the proliferation, migration and apoptosis of human colorectal carcinoma HCT‑116 cells

Curcumin is the main component of the Chinese herbal plant turmeric, which has been demonstrated to possess antitumor and other pharmacological properties. The aim of the present study was to investigate the effects of curcumin on the viability, migration and apoptosis of human colorectal carcinoma HCT-116 cells, and to explore the underlying molecular mechanisms. In addition, it was investigated whether the antitumor effect of curcumin on HCT-116 cells could match that of the chemotherapeutic drug 5-fluorouracil (5-FU). HCT-116 cells were treated with curcumin (10, 20 and 30 µM) and 5-FU (500 µM), and cell viability and proliferation were detected by Cell Counting Kit-8 and colony formation assays, respectively. The migration and invasion of treated cells were determined using Transwell and carboxyfluorescein succinimidyl amino ester fluorescent labeling assays. Cell cycle distribution and apoptosis rates were detected by flow cytometry. Furthermore, cell morphology changes associated with apoptosis were observed by fluorescence microscopy with acridine orange/ethidium bromide dual staining. To investigate the possible underlying molecular mechanisms, the gene and protein levels of Fas, Fas-associated via death domain (FADD), caspase-8, caspase-3, matrix metalloproteinase (MMP)-9, nuclear factor (NF)-κB, E-cadherin and claudin-3 were detected using quantitative PCR analysis, zymography and western blotting. The results revealed that curcumin markedly inhibited the viability and proliferation of HCT-116 cells in a dose- and time-dependent manner. The migration, aggregation and invasion of HCT-116 cells into the lungs of mice were decreased by curcumin treatment in a dose-dependent manner. S-phase arrest and gradually increased apoptotic rates of HCT-116 cells were observed with increasing curcumin concentrations. Additionally, the mRNA and protein levels of apoptosis-associated proteins (Fas, FADD, caspase-8 and caspase-3) and E-cadherin in HCT-116 cells were upregulated following treatment with curcumin in a dose-dependent manner. By contrast, the expression of migration-associated proteins, including MMP-9, NF-κB and claudin-3, was downregulated with increasing curcumin concentrations. These data suggested that the inhibitory effect of curcumin on HCT-116 cells may match that of 5-FU. Therefore, curcumin induced cell apoptosis and inhibited tumor cell metastasis by regulating the NF-κB signaling pathway, and its therapeutic effect may be comparable to that of 5-FU.

The roles of miRNAs' clinical efficiencies in the colorectal cancer pathobiology: A review article

MiRNAs (microRNAs) are defined as micro directors and regulators of gene expression. Since altered miRNA expression is signified in the pathobiology of diverse cancers such as colorectal cancers (CRCs), these molecules are described as therapeutic targets, either. Manipulation of miRNAs could lead to further therapy for chemo and radio-resistant CRCs. The usage of microRNAs has indicated prominent promise in the prognosis and diagnosis of CRC, because of their unique expression pattern associated with cancer types and malignancies. Nowadays, many researchers are analyzing the correlation between miRNA polymorphisms and cancer risk. With continuous incompatibility in colorectal cancer (CRC) miRNAs expression data, it is critical to move toward the content of a "pre-laboratory" analysis to speed up efficient accuracy medicine and translational study. Pathway study for the highest expressed miRNAs- regulated target genes resulted in the identification of a considerable number of genes associated with CRC pathway including PI3K, TGFβ, and APC. In this review, we aimed to collect fruitful information about miRNAs and their potential roles in CRC, and provide a meta-analysis of the most frequently studied miRNAs in association with the disease.

Effect of KNL1 on the proliferation and apoptosis of colorectal cancer cells

Objective:

To identify the expression of kinetochore scaffold 1 (KNL1) in colorectal tumor tissues and to clarify the role of this gene in the proliferation capability of colorectal cancer cells.

Methods:

A total of 108 paired colorectal tumor and normal tissue samples were collected from patients with colorectal cancer and subjected to quantitative polymerase chain reaction and immunohistochemistry analyses. Expression levels of KNL1 mRNA and protein were compared between tumor and normal tissues, and KNL1 levels were evaluated in relation to the patients’ tumor differentiation, sex, lymph node metastasis, TNM stage, infiltration depth, age, and tumor location. Survival curves were also constructed and compared between patients with tumor samples with and without KLN1 protein expression. KNL1 was under-expressed in colorectal cancer cells in vitro using lentiviral transfection with short hairpin RNA, and its function was evaluated by proliferation, colony-formation, and apoptosis assays. Expression levels of BUB1 protein were also compared between tumor and normal tissues, and the correlation between KNL1 expression and BUB1 expression in colorectal cancer tissues was examined.

Results:

KNL1 mRNA and protein were both highly expressed in colorectal tumor tissues compared with paired normal tissues. KNL1 downregulation significantly inhibited colorectal cancer cell proliferation and colony formation, and promoted apoptosis. KNL1 protein expression was significantly associated with tumor differentiation, but not with sex, lymph node metastasis, TNM stage, infiltration depth, age, or tumor location. KNL1 protein expression was also significantly associated with poorer survival. Moreover, there was a significant correlation between KNL1 and BUB1 in colorectal cancer tissues.

Conclusions:

KNL1 plays an effective role in decreasing apoptosis and promoting the proliferation of colorectal cancer cells, suggesting that its inhibition may represent a promising therapeutic approach in patients with colorectal cancer.

Diagnostic Value Investigation and Bioinformatics Analysis of miR-31 in Patients with Lymph Node Metastasis of Colorectal Cancer

Colorectal cancer (CRC) is one of the most frequent cancers occurring in developed countries. Distant CRC metastasis causes more than 90% of CRC-associated mortality. MicroRNAs (miRNAs) play a key role in regulating tumor metastasis and could be potential diagnostic biomarkers in CRC patients. This study is aimed at identifying miRNAs that can be used as diagnostic biomarkers for CRC metastasis. Towards this goal, we compared the expression of five miRNAs commonly associated with metastasis (i.e., miR-10b, miR-200c, miR-155, miR-21, and miR-31) between primary CRC (pCRC) tissues and corresponding metastatic lymph nodes (mCRC). Further, bioinformatics analysis of miR-31 was performed to predict target genes and related signaling pathways. Results showed that miR-31, miR-21, miR-10b, and miR-155 expression was increased to different extents, while miR-200c expression was lower in mCRC than that in pCRC. Moreover, we found that the level of both miR-31 and miR-21 was notably increased in pCRC when lymph node metastasis (LNM) was present, and the increase of miR-31 expression was more profound. Hence, upregulated miR-31 and miR-21 expression might be a miRNA signature in CRC metastasis. Moreover, we detected a higher miR-31 level in the plasma of CRC patients with LNM compared to patients without LNM or healthy individuals. With the bioinformatics analysis of miR-31, 121 putative target genes and transition of mitotic cell cycle and Wnt signaling pathway were identified to possibly play a role in CRC progression. We next identified seven hub genes via module analysis; of these, TNS1 was most likely to be the target of miR-31 and had significant prognostic value for CRC patients. In conclusion, miR-31 is significantly increased in the cancer tissues and plasma of CRC patients with LNM; thus, a high level of miR-31 in the plasma is a potential biomarker for the diagnosis of LNM of CRC.

MicroRNA-145 Inhibits Cell Migration and Invasion in Colorectal Cancer by Targeting TWIST

Introduction

MicroRNAs function as oncogenes or tumor suppressors in the development of various human cancers. We investigated the effect of microRNA-145 (miR-145) on colorectal cancer (CRC) cell invasion and migration.

Methods

The levels of miR-145 in CRC cells were examined by quantitative PCR; Western blotting was used to detect TWIST1 (twist family bHLH transcription factor 1) protein and the epithelial–mesenchymal transition (EMT)-related proteins (E-cadherin, vimentin). Then, we transfected miR-145 mimics or inhibitor into CRC cells and used the wound healing and Transwell invasion assays to investigate their migration and invasive capability, respectively.

Results

The miR-145 mimics suppressed CRC cell invasion and migration significantly; in contrast, miR-145 downregulation had the opposite effect. Furthermore, miR-145 regulated TWIST1 levels negatively at transcriptional level. TWIST1 knockdown significantly inhibited the CRC cell migration ability and the number of CRC cells that crossed the Transwell membrane. There was no significant difference in terms of migration and invasive capability after the cells had been transfected with miR-145 mimics or inhibitor plus TWIST1 small interfering RNA (siRNA) as compared to the TWIST1 siRNA–only group. Furthermore, we demonstrate that the inhibition of miR-145 could enhance the capability for lung metastasis in vivo.

Conclusion

Taken together, these findings indicate that miR-145 acts as a new tumor suppressor by regulating TWIST1 and plays a vital role in the invasive and migration ability of CRC cells.

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.

MicroRNAs and complex diseases: from experimental results to computational models

Plenty of microRNAs (miRNAs) were discovered at a rapid pace in plants, green algae, viruses and animals. As one of the most important components in the cell, miRNAs play a growing important role in various essential and important biological processes. For the recent few decades, amounts of experimental methods and computational models have been designed and implemented to identify novel miRNA-disease associations. In this review, the functions of miRNAs, miRNA-target interactions, miRNA-disease associations and some important publicly available miRNA-related databases were discussed in detail. Specially, considering the important fact that an increasing number of miRNA-disease associations have been experimentally confirmed, we selected five important miRNA-related human diseases and five crucial disease-related miRNAs and provided corresponding introductions. Identifying disease-related miRNAs has become an important goal of biomedical research, which will accelerate the understanding of disease pathogenesis at the molecular level and molecular tools design for disease diagnosis, treatment and prevention. Computational models have become an important means for novel miRNA-disease association identification, which could select the most promising miRNA-disease pairs for experimental validation and significantly reduce the time and cost of the biological experiments. Here, we reviewed 20 state-of-the-art computational models of predicting miRNA-disease associations from different perspectives. Finally, we summarized four important factors for the difficulties of predicting potential disease-related miRNAs, the framework of constructing powerful computational models to predict potential miRNA-disease associations including five feasible and important research schemas, and future directions for further development of computational models.

Prognostic significance of lymphovascular invasion in colorectal cancer and its association with genomic alterations

BACKGROUND

Lymphovascular invasion (LVI) is suggested to be an early and important step in tumor progression toward metastasis, but its prognostic value and genetic mechanisms in colorectal cancer (CRC) have not been well investigated.

AIM

To investigate the prognostic value of LVI in CRC and identify the associated genomic alterations.

METHODS

We performed a retrospective analysis of 1219 CRC patients and evaluated the prognostic value of LVI for overall survival by the Kaplan-Meier method and multivariate Cox regression analysis. We also performed an array-based comparative genomic hybridization analysis of 47 fresh CRC samples to examine the genomic alterations associated with LVI. A decision tree model was applied to identify special DNA copy number alterations (DCNAs) for differentiating between CRCs with and without LVI. Functional enrichment and protein-protein interaction network analyses were conducted to explore the potential molecular mechanisms of LVI.

RESULTS

LVI was detected in 150 (12.3%) of 1219 CRCs, and the presence was positively associated with higher histological grade and advanced tumor stage (both P < 0.001). Compared with the non-LVI group, the LVI group showed a 1.77-fold (95% confidence interval: 1.40-2.25, P < 0.001) increased risk of death and a significantly lower 5-year overall survival rate (P < 0.001). Based on the comparative genomic hybridization data, 184 DCNAs (105 gains and 79 losses) were identified to be significantly related to LVI (P < 0.05), and the majority were located at 22q, 17q, 10q, and 6q. We further constructed a decision tree classifier including seven special DCNAs, which could distinguish CRCs with LVI from those without it at an accuracy of 95.7%. Functional enrichment and protein-protein interaction network analyses revealed that the genomic alterations related to LVI were correlated with inflammation, epithelial-mesenchymal transition, angiogenesis, and matrix remodeling.

CONCLUSION

LVI is an independent predictor for survival in CRC, and its development may correlate with inflammation, epithelial-mesenchymal transition, angiogenesis, and matrix remodeling.

Selected Aspects of Chemoresistance Mechanisms in Colorectal Carcinoma-A Focus on Epithelial-to-Mesenchymal Transition, Autophagy, and Apoptosis

Chemoresistance has been found in all malignant tumors including colorectal carcinoma (CRC). Nowadays chemoresistance is understood as a major reason for therapy failure, with consequent tumor growth and spreading leading ultimately to the patient's premature death. The chemotherapy-related resistance of malignant colonocytes may be manifested in diverse mechanisms that may exist both prior to the onset of the therapy or after it. The ultimate function of this chemoresistance is to ensure the survival of malignant cells through continuing adaptation within an organism, therefore, the nature and spectrum of cell-survival strategies in CRC represent a highly significant target of scientific inquiry. Among these survival strategies employed by CRC cells, three unique but significantly linked phenomena stand out-epithelial-to-mesenchymal transition (EMT), autophagy, and cell death. In this mini-review, current knowledge concerning all three mechanisms including their emergence, timeline, regulation, and mutual relationships will be presented and discussed.

Development of novel predictive miRNA/target gene pathways for colorectal cancer distance metastasis to the liver using a bioinformatic approach

Background

Liver metastases are the major cause of colorectal cancer (CRC)-related deaths. However, there is no reliable clinical predictor for CRC progression to liver metastasis. In this study, we investigated possible predictors (miRNAs and biomarkers) for clinical application.

Methodology

The Gene Expression Omnibus (GEO) datasets GSE49355, GSE41258 and GSE81558 for genes and GSE54088 and GSE56350 for miRNAs were used to identify common differentially expressed genes (DEGs) and miRNAs between primary CRC tissues and liver metastases. The identified miRNAs and their targets from the DEGs were verified in datasets comprising gene, miRNA and miRNA exosome profiles of CRC patients with no distant metastases (M0) and distant metastases (M1); the interaction networks and pathways were also mapped.

Results

There were 49 upregulated and 13 downregulated DEGs and 16 downregulated and 14 upregulated miRNAs; between the DEGs and miRNA targets, there were five upregulated and four downregulated genes. MiR-20a was strongly correlated with the status of liver metastasis. MiR-20a, miR499a, and miR-576-5p were highly correlated with the metastatic outcomes. MiR-20a was significantly highly expressed in the M1 group. In an analysis of the miRNA target genes, we found that CDH2, KNG1, and MMP2 were correlated with CRC metastasis. We demonstrated a new possible pathway for CRC metastasis: miR-576-5p/F9, miR20a/MMP2, CTSK, MMP3, and miR449a/P2RY14. The regulation of IGF transport and uptake by IGFBPs, extracellular matrix organization, signal transduction and the immune system were the enriched pathways.

Conclusion

This model can predict CRC to liver metastases and the pathways involved, which can be clinically applicable.

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) and its receptor PROKR2 are associated to human colorectal cancer progression and peritoneal carcinomatosis

BACKGROUND

The highest risk factor for mortality among malignant tumors is metastasis. Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is an angiogenic factor which biological activity is mediated via two G protein-coupled receptors, prokineticin receptor1 (PROKR1) and PROKR2. Recent studies suggested that EG-VEGF expression is deregulated in multiple cancers including colorectal cancer (CRC).

METHODS

Using distinctive CRC and peritoneal carcinomatosis (PC) cohorts and a corresponding control cohort, we determined the circulating levels of EG-VEGF and its in situ expression, and that of its related receptors.

RESULTS

Circulating EG-VEGF levels were significantly increased in patients with metastatic PC compared to CRC and control patients (p< 0.05). Furthermore, according to clinicopathologic examinations, local EG-VEGF expression correlated with higher tumor and nodal stages (p< 0.001) of CRC. EG-VEGF and PROKR2 were highly expressed in colorectal primary lesions compared to positive controls. PROKR1 expression was lower and did not change in tumor specimens. Also, EG-VEGF and its receptor PROKR2 were differentially expressed in the colorectal primary lesions and in the control groups.

CONCLUSION

Altogether these findings suggest that EG-VEGF/receptors system might be an important actor in the CRC progression into PC and might be involved in the ability of tumor cells to invade other organs. Circulating EG-VEGF could be proposed as a prognostic marker in human CRC and its progression into PC.

Early metastatic colorectal cancers show increased tissue expression of miR-17/92 cluster members in the invasive tumor front

Accurate prediction of regional lymph node metastases (LNM) in endoscopically resected pT1 colorectal cancer (CRC) is crucial in treatment stratification for subsequent radical surgery. Several miRNAs have been linked to CRC invasion and metastasis, including the oncogenic miR-17/92 cluster, and expression levels might have predictive value in the risk assessment of early metastatic progression in CRC. We performed global miRNA microarray using tissue samples from the invasive front of pT1 CRC and investigated associations of the miR-17/92 cluster and presence of LNM. In total, 56 matched pT1 CRCs were thoroughly clinicopathologically characterized, and miRNA microarrays were performed on invasive front tissue samples. Global miRNA intensities were screened using paired t-tests between pT1pN+ and pT1pN0. Associations between miR-17/92 and histopathological features were analyzed using general linear models and tumor cell adjusted expression intensities. miR-17-3p and miR-92a were significantly higher expressed in the invasive front of tumors with LNM compared to those without, corresponding to 1.53-fold higher expression of miR-17-3p (95%CI: 1.04-2.24, P = .030) and 1.28-fold higher expression of miR-92a (95%CI: 1.01-1.68, P = .042). An inverse association between miR-19a and presence of high-grade tumor budding was observed (1.55-fold, 95%CI: 1.13-2.12, P = .008). We provide evidence for associations between early regional LNM and high expression levels of the miR-17/92 cluster members: miR-17-3p and miR-92a, in the invasive front of CRC. Our results support a role for the miR-17/92 cluster in early metastatic progression of CRC and calls for further investigation.

MiR-195 suppresses colon cancer proliferation and metastasis by targeting WNT3A

MicroRNAs (miRNAs) are a novel class of diagnostic and therapeutic target in cancer. Here, we aimed to explore the effects and mechanism of miR-195 regulation in colon cancer. The expressions of several putative miRNAs in colon tumors, compared to those in normal tissues, were investigated by bioinformatical analysis of a Gene Expression Omnibus database. Quantitative real-time PCR analysis (qRT-PCR) was used to validate the identified changes in normal tissues, primary tumors, and metastatic tumors. MTT, soft agar colony formation, and transwell assays were used to evaluate the effects of miR-195 overexpression or inhibition on cell viability, proliferation, migration, and invasion. Targets of miR-195 were identified by TargetScan, and subsequently verified by qRT-PCR and Western blot. The role of miR-195 in the β-catenin pathway was also studied using RT-PCR and Western blot. MiR-195 expression was downregulated in colon carcinoma tissues and negatively correlated with the metastatic potential. While transfecting miR-195 mimics decreased the proliferation, migration, and invasion of colon cancer cells, miR-195 inhibition exerted opposing effects. WNT3A was identified as a direct target of miR-195. β-catenin was also downregulated by miR-195 in colon cancers. MiR-195 downregulation is associated with the enhanced proliferation, migration, and invasion of colon cancer. MiR-195 directly downregulates WNT3A. Our results indicate that miR-195 is a potential diagnostic marker and therapeutic target for improving the clinical management of colon cancer.

Roles of long noncoding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is the 3^rd most common malignancies worldwide. Metastasis is responsible for more than 90% CRC patients' death. Long noncoding RNAs (lncRNAs) are an important class of transcribed RNA molecules greater than 200 nucleotides in length. With the development of whole genome sequencing technologies, they have been gained more attention. Accumulating evidences suggest that abnormal expression of lncRNAs in diverse diseases are involved in various biological functions such as proliferation, apoptosis, metastasis and differentiation by acting as epigenetic, splicing, transcriptional or post-transcriptional regulators. Aberrant expression of lncRNAs has also been found in CRC. Besides, recent studies have indicated that lncRNAs play important roles in tumourigenesis and cancer metastasis. They participate in the process of metastasis by activing or inhibiting the metastatic pathways. However, their functions on the development of cancer metastasis are poorly understood. In this review, we highlight the findings of roles for lncRNAs in CRC metastasis and review the metastatic pathways of lncRNAs leading to cancer metastasis in CRC, including escape of apoptosis, epithelial-mesenchymal transition (EMT), angiogenesis and invasion, migration and proliferation. Furthermore, we also discuss the potential clinical application of lncRNAs in CRC as diagnostic markers and therapeutic targets.

Role of RbBP5 and H3K4me3 in the vicinity of Snail transcription start site during epithelial-mesenchymal transition in prostate cancer cell

EMT (epithelial-mesenchymal transition) occurs in a wide range of tumor types, and has been shown to be crucial for metastasis. Epigenetic modifications of histones contribute to chromatin structure and result in the alterations in gene expression. Tri-methylation of histone H3 lysine 4 (H3K4me3) is associated with the promoters of actively transcribed genes and can serve as a transcriptional on/off switch. RbBP5 is a component of the COMPASS/ -like complex, which catalyzes H3K4me3 formation. In this study, we found that in the process of TGF-Beta1 induced EMT in the prostate cancer cell line DU145, H3K4me3 enrichment and RbBP5 binding increased in the vicinity of Snail (SNAI1) transcription start site. Knocking-down of RbBP5 notably decreased Snail expression and EMT. Recruitment of RbBP5 and formation of H3K4me3 at Snail TSS during EMT depend on binding of SMAD2/3 and CBP at Snail TSS. This study links the SMAD2/3 signal with Snail transcription via a histone modification - H3K4me3. Furthermore, our research also demonstrates that RbBP5 and even WRAD may be a promising therapeutic candidates in treating prostate cancer metastasis, and that DU145 cells maintain their incomplete mesenchymal state in an auto/paracrine manner.

Predictive microRNAs for lymph node metastasis in endoscopically resectable submucosal colorectal cancer

Accurate prediction of regional lymph node metastasis (LNM) in endoscopically resected T1-stage colorectal cancers (CRCs) can reduce unnecessary surgeries. To identify miRNA markers that can predict LNM in T1-stage CRCs, the study was conducted in two phases; (I) miRNA classifier construction by miRNA-array and quantitative reverse transcription PCR (qRT-PCR) using 36 T1-stage CRC samples; (II) miRNA classifier validation in an independent set of 20 T1-stage CRC samples. The expression of potential downstream target genes of miRNAs was assessed by immunohistochemistry. In the discovery analysis by miRNA microarray, expression of 66 miRNAs were significantly different between LNM-positive and negative CRCs. After qRT-PCR validation, 11 miRNAs were consistently significant in the combined classifier construction set. Among them, miR-342-3p was the most significant one (P=4.3×10-4). Through logistic regression analysis, we developed a three-miRNA classifier (miR-342-3p, miR-361-3p, and miR-3621) for predicting LNM in T1-stage CRCs, yielding the area under the curve of 0.947 (94% sensitivity, 85% specificity and 89% accuracy). The discriminative ability of this system was consistently reliable in the independent validation set (83% sensitivity, 64% specificity and 70% of accuracy). Of the potential downstream targets of the three-miRNAs, expressions of E2F1, RAP2B, and AKT1 were significantly associated with LNM. In conclusion, this classifier can predict LNM more accurately than conventional pathologic criteria and our study results may be helpful to avoid unnecessary bowel surgery after endoscopic resection in early CRC.

FOXR2 Promotes the Proliferation, Invasion, and Epithelial-Mesenchymal Transition in Human Colorectal Cancer Cells

Forkhead box R2 (FOXR2), a member of the FOX gene family, has not been very well investigated for its role in cancer. A recent study has shown that FOXR2 is highly expressed in breast cancer samples and is associated with poor prognosis. In addition, FOXR2 was identified as an oncogene in medulloblastoma. Nevertheless, whether FOXR2 plays a role in colorectal cancer (CRC) remains unclear. In the present study, we conducted several in vitro and in vivo studies to investigate the expression and effect of FOXR2 in CRC. The study results demonstrated that FOXR2 was upregulated in CRC tissues and cells. Downregulation of FOXR2 inhibited CRC cell proliferation, invasion, and the epithelial-mesenchymal transition (EMT) phenotype in vitro and also suppressed CRC cell growth and metastasis in vivo. Furthermore, downregulation of FOXR2 remarkably reduced the protein expression of Shh, Gli1, and Ptch1 in SW480 cells. Taken together, our data suggested that FOXR2 significantly promoted proliferation, invasion, and EMT of CRC cells. All these findings provided evidence for the role of FOXR2 as an oncogene in CRC development.

Identification of metastasis-associated microRNAs in serum from rectal cancer patients

MicroRNAs (miRNAs) are promising prognostic and diagnostic biomarkers due to their high stability in blood. Here we investigate the expression of miRNAs and other noncoding (nc) RNAs in serum of rectal cancer patients. Serum from 96 rectal cancer patients was profiled using small RNA sequencing and expression of small RNAs was correlated with the clinicopathological characteristics of the patients. Multiple classes of RNAs were detected, including miRNAs and fragments of tRNAs, snoRNAs, long ncRNAs, and other classes of RNAs. Several miRNAs, miRNA variants (isomiRs) and other ncRNAs were differentially expressed between Stage IV and Stage I-III rectal cancer patients, including several members of the miR-320 family. Furthermore, we show that high expression of miR-320d as well as one tRNA fragment is associated with poor survival. We also show that several miRNAs and isomiRs are differentially expressed between patients receiving preoperative chemoradiotherapy and patients who did not receive any treatment before serum collection. In summary, our study shows that the expression of miRNAs and other small ncRNAs in serum may be used to predict distant metastasis and survival in rectal cancer.

Towards personalized medicine of colorectal cancer

Efforts in colorectal cancer (CRC) research aim to improve early detection and treatment for metastatic stages which could translate into better prognosis of this disease. One of the major challenges that hinder these efforts is the heterogeneous nature of CRC and involvement of diverse molecular pathways. New large-scale 'omics' technologies are making it possible to generate, analyze and interpret biological data from molecular determinants of CRC. The developments of sophisticated computational analyses would allow information from different omics platforms to be integrated, thus providing new insights into the biology of CRC. Together, these technological advances and an improved mechanistic understanding might allow CRC to be clinically managed at the level of the individual patient. This review provides an account of the current challenges in CRC management and an insight into how new technologies could allow the development of personalized medicine for CRC.

MicroRNA-23a promotes pancreatic cancer metastasis by targeting epithelial splicing regulator protein 1

miR-23a plays vital roles in various cancer metastases. Here, we found that miR-23a expression was significantly up-regulated in pancreatic cancer tissues compared with adjacent normal tissues. miR-23a up-regulation was significantly associated with differentiated degree, lymphoid nodal status, tumor invasion and poor survival rate in pancreatic cancer patients. We also found that miR-23a expression was significantly up-regulated in lymph node metastatic tissues and in pancreatic cancer cells that underwent epithelial-mesenchymal transition (EMT). miR-23a down-regulation blocked TGF-β1-induced EMT and reversed the phenotype of EMT in Panc-1 cells. Furthermore, miR-23a down-regulation inhibited Panc-1 cells migration and invasion in vitro and liver metastases in vivo. But the effect of miR-23a up-regulation in Aspc-1 cells was opposite to that of miR-23a down-regulation in Panc-1 cells. Epithelial splicing regulatory protein 1 (ESRP1) was identified as a direct target of miR-23a. Restoration of ESRP1 rescued the effect of miR-23a on pancreatic cancer cell progression. Moreover, miR-23a up-regulation in Aspc-1 cells induced a shift in CD44 expression from variant isoforms (CD44v) to the standard isoform (CD44s) together with increased FGFR2 IIIc mRNA levels, and decreased FGFR2 IIIb expression during EMT. But the effect of miR-23a down-regulation in Panc-1 cells was opposite to that of miR-23a up-regulation in Aspc-1 cells. In addition, the effect of miR-23a up-regulation was partly reversed by ESRP1 over-expression. Taken together, our findings indicated that miR-23a functions as an oncogene by regulating ESRP1 in pancreatic cancer.

The role of microRNAs in colorectal liver metastasis: Important participants and potential clinical significances

Colorectal cancer is one of the most common cancers in the world, and liver metastasis is the leading direct cause of cancer-related deaths in colorectal cancer. MicroRNA is involved in tumor metastasis in many aspects; mounting studies have shown that microRNAs play important roles in colorectal liver metastasis. Although lots of reviews about the association between microRNAs and colorectal cancer metastasis have been published, the reviews specifically focusing on microRNAs and colorectal liver metastasis are still lacking in the literature. To address this issue, here, we summarize the underlying mechanisms of microRNAs in colorectal liver metastasis and explore their potential clinical applications in this aspect.

Decreased expression of miR-193a-3p is associated with poor prognosis in colorectal cancer

Epithelial-mesenchymal transition (EMT) is an early and key process in the metastatic cascade during the progression of colorectal cancer (CRC). The aim of the present study was to identify deregulated EMT-related microRNAs (miRNAs/miRs) of CRC and assess the effect of differentially expressed miRNAs on the prognosis of patients with CRC. Genome-wide expression profiling of miRNAs was assessed in 3 EMT-negative and 3 EMT-positive CRC tissues. Differentially expressed miRNA was further validated in 90 pairs of CRC and corresponding paracarcinoma tissues using the reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A total of 6 miRNAs (miR-10a-5p miR-204-3p, miR-1224-3p, miR-193a-3p, miR-365a-3p and miR-3678-3p) were identified to be differentially expressed between different EMT statuses of CRC tissues. Following validation using RT-qPCR, 3 miRNAs (miR-10a-5p, miR-365a-3p and miR-193a-3p) were selected for subsequent studies. The expression levels of miR-10a-5p, miR-193a-3p and miR-365a-3p were markedly increased compared with levels in corresponding paracarcinoma tissues. Survival analyses revealed that down-regulation of miR-193a-3p was associated with worse prognosis of patients with CRC, particularly in female and older patients. The results of the present study indicate that miR-193a-3p may be an EMT-related biomarker and serve as a novel prognostic factor for CRC.

Regulatory miRNAs in Colorectal Carcinogenesis and Metastasis

Colorectal cancer is one of the most common malignancies and is the second-leading cause of cancer-related death world-wide, which is linked to genetic mutations, epigenetic alterations, and oncogenic signaling activation. MicroRNAs, one of the categories of epigenetics, have been demonstrated significant roles in carcinogenesis and progression through regulating of oncogenic signaling pathways, stem cells, epithelial-mesenchymal transition, and metastasis. This review summarizes the roles of microRNAs in the regulating of Wnt, Ras, TGF-β, and inflammatory signaling pathways, stemness, and epithelial-mesenchymal transition, for carcinogenesis and metastasis in colorectal cancer. Improving our understanding of the mechanisms of regulatory interactions of microRNAs with signaling pathways in colorectal cancer formation and progression will aid in determining the genes responsible for colorectal cancer initiation, progression, metastasis, and recurrence and, finally, in developing personalized approaches for cancer prevention and therapy.

MicroRNA-194 modulates epithelial-mesenchymal transition in human colorectal cancer metastasis

MicroRNAs (miRNAs), as key regulators of gene expression, are closely related to tumor occurrence and progression. MiR-194 has been proved as a tumor regulatory factor in various cancers; however, the biological function and mechanism of action in colorectal cancer (CRC) have not been well explored. In the present study, we found that miR-194 expression is upregulated in CRC clinical specimens, while overexpression of miR-194 promotes cell migration and invasion in CRC cell lines. Besides, miR-194 significantly influenced the epithelial–mesenchymal transition (EMT) markers by downregulating E-cadherin expression (P<0.01) and upregulating vimentin and MMP-2 expression (P<0.001, P<0.05). Cell migration is the cell movement related to actin cytoskeleton. In this study, we found miR-194 increased cell polarization in SW480 cells. Moreover, zymography assay showed that miR-194 significantly upregulated the gelatin-degrading activity of MMP-2 (P<0.01). Collectively, our findings suggest that miR-194 functions as a tumor promoter in CRC, which may provide new insights for the study of CRC development and metastasis.

TUC.338 promotes invasion and metastasis in colorectal cancer

Ultraconserved regions (UCRs) are non-protein coding gene sequences that are strictly conserved across among different species. Emerging evidence demonstrates that transcribed ultraconserved regions (TUCRs) encoding noncoding RNAs serve as regulators of gene expression. In recent decades, increasing evidence implicates the involvement of UCRs in carcinogenesis. The role of TUC.338 in cervical cancers was an oncogene in previous studies. Until now, the role of TUC.338 in colorectal cancers remains undefined. This study revealed that TUC.338 is significantly up-regulated in colorectal cancers (CRC) tissue and CRC cell lines, and the up-regulated TUC.338 is associated with lymph node metastasis. Transfection with small interfering RNA (siRNA) markedly inhibited cell migration and invasion in SW480 and HCT116 colorectal cancer cell lines. TIMP-1 was demonstrated to be negatively regulated by TUC.338 at the posttranscriptional level, via a specific target site within the 3' untranslated region by dual-luciferase reporter assay. The expression of TIMP-1 was also observed to inversely correlate with TUC.338 expression in CRC tissues. Over-expression of TIMP-1 with migRI-TIMP-1-GFP inhibited CRC cell migration and invasion and down-regulates MMP9, resembling that of TUC.338-siRNA. Thus, these findings suggested that TUC.338 acts as a novel oncogene by targeting the TIMP-1 gene thus promoting colorectal cancer cell migration and invasion.

Colorectal cancer cell-derived microRNA200 modulates the resistance of adjacent blood endothelial barriers in vitro

Since cancer cells, when grown as spheroids, display drug sensitivity and radiation resistance patterns such as seen in vivo we recently established a three‑dimensional (3D) in vitro model recapitulating colorectal cancer (CRC)-triggered lymphatic endothelial cell (LEC)‑barrier breaching to study mechanisms of intra‑/extravasation. CRC metastasizes not only through lymphatics but also through blood vessels and here we extend the 3D model to the interaction of blood endothelial cells (BECs) with naïve and 5‑fluorouracil (5‑FU)‑resistant CRC CCL227 cells. The 3D model enabled quantifying effects of tumour‑derived microRNA200 (miR200) miR200a, miR200b, miR200c, miR141 and miR429 regarding the induction of so-called 'circular chemorepellent‑induced defects' (CCIDs) within the BEC‑barrier, which resemble gates for tumour transmigration. For this, miR200 precursors were individually transfected and furthermore, the modulation of ZEB family expression was analysed by western blotting. miR200c, miR141 and miR429, which are contained in exosomes from naïve CCL227 cells, downregulated the expression of ZEB2, SNAI and TWIST in BECs. The exosomes of 5‑FU‑resistant CCL227‑RH cells, which are devoid of miR200, accelerated CCID formation in BEC monolayers as compared to exosomes from naïve CCL227 cells. This confirmed the reported role of ZEB2 and SNAI in CRC metastasis and highlighted the active contribution of the stroma in the metastatic process. CCL227 spheroids affected the integrity of BEC and LEC barriers alike, which was in agreement with the observation that CRC metastasizes via blood stream (into the liver) as well as via lymphatics (into lymph nodes and lungs). This further validated the CRC/LEC and CRC/BEC in vitro model to study mechanisms of CRC spreading through vascular systems. Treatment of CCL227‑RH cells with the HDAC inhibitors mocetinostat and sulforaphane reduced CCID formation to the level triggered by naïve CCL227 spheroids, however, without significantly influencing miR200 expression in CCL227-RH cells.

Investigating intra-tumor heterogeneity and expression gradients of miR-21, miR-92a and miR-200c and their potential of predicting lymph node metastases in early colorectal cancer

INTRODUCTION

miR-21, miR-92a and miR-200c are regulators of pathways involved in migration, intravasation and metastasis, and their tumor expression levels have been proposed as potential prognostic markers in colorectal cancer (CRC). In two parallel cohorts we examine intra-tumor expression levels in early stage CRC tissue in order to determine intra-tumor heterogeneity, potential systematic intra-tumor expression gradients of the miRNAs and to investigate the association to metastatic disease in early stage CRC.

MATERIAL AND METHODS

Two parallel studies on archived formalin-fixed paraffin-embedded (FFPE) CRC tissue. Intra-tumor and inter-patient variances were analyzed in 9 early metastatic CRCs by measuring expression levels by qRT-PCR on isolated tissue samples from luminal, central and invasive border zones. Associations between miRNA expression levels and early metastasizing tumors was investigated in FFPE tissue from invasive border and central tumor zones from 47 early metastatic CRCs matched with 47 non-metastatic CRCs. Intra-tumor expression gradients were analyzed on both cohorts.

RESULTS

Mean intra-tumor coefficient of variation in the heterogeneity cohort was 38.5% (range: 33.1-49.0%) only slightly less than variation between patients (45.1%, range 37.0-49.5%). We demonstrated systematic expression gradients between tumor zones equal to a 3.23 (p=0.003) and 1.36 (p=0.014) fold lower expression in invasive areas for miR-200c, 1.52 (p<0.001) and 1.27 (p=0.021) fold lower expression in invasive areas for miR-92a. For miR-21 we found a 1.75 (p<0.001) and 1.21 (p=0.064) fold higher expression in invasive areas compared to luminal and central zones, respectively. No significant difference in expression levels between metastatic and non-metastatic tumors was demonstrated, nor a difference in intra-tumor gradients between metastatic and non-metastatic tumors.

CONCLUSION

This study provides evidence for moderate intra-tumor and inter-patient heterogeneities of three well-described potential prognostic markers in CRC. We demonstrate intra-tumor expression gradients indicating a differentiated expression of the target miRNAs between functional tumor zones, but the potential role as markers of early metastatic disease is still not fully clarified.

Epithelial-mesenchymal transition, inflammatory bowel disease and colitis associated colorectal cancer

Chronic inflammation can induce the formation of a wide variety of tumors. Inflammatory bowel disease is one of the major risk factors for colorectal cancer. Epithelial-mesenchymal transition (EMT) can promote the invasion and metastasis of a variety of cancer cells, including colorectal cancer cells. Different kinds of inflammatory cytokines produced in inflammatory bowel disease could mediate the activation of EMT through a series of pathways, and thus promote the occurrence and development of colitis associated colorectal cancer. This article explores the relationship among EMT, inflammatory bowel disease and colitis associated colorectal cancer, with an aim to provide new ideas and methods for the clinical treatment of colitis associated colorectal cancer.

MicroRNA-543 suppresses colorectal cancer growth and metastasis by targeting KRAS, MTA1 and HMGA2

miR-543 has been implicated as having a critical role in the development of breast cancer, endometrial cancer and hepatocellular carcinoma. However, the exact clinical significance and biological functions of miR-543 in colorectal cancer (CRC) remain unclear. Here, we found that miR-543 expression significantly downregulated in tumors from patients with CRC, APCMin mice and a mouse model of colitis-associated colon cancer. miR-543 level was inversely correlated with the metastatic status of patients with CRC and the metastatic potential of CRC cell lines. Moreover, ectopic expression of miR-543 inhibited the proliferation and metastasis of CRC cells in vitro and in vivo by targeting KRAS, MTA1 and HMGA2. Conversely, miR-543 knockdown promoted the proliferation, migration and invasion of CRC cells in vitro and augmented tumor growth and metastasis in vivo. Furthermore, we found that miR-543 expression was negatively correlated with the levels of KRAS, MTA1 and HMGA2 in clinical samples. Collectively, these data show that miR-543 inhibits the proliferation and metastasis of CRC cells by targeting KRAS, MTA1 and HMGA2. Our study highlights a pivotal role for miR-543 as a suppressor in the regulation of CRC growth and metastasis and suggests that miR-543 may serve as a novel diagnostic and prognostic biomarker for CRC metastasis.

MiR-381 functions as a tumor suppressor in colorectal cancer by targeting Twist1

MiR-381 has been reported to be dysregulated in several human cancers. However, the function and mechanism of miR-381 in colorectal cancer (CRC) remains unclear. In the present study, the miR-381 expression was assessed in a cohort of 113 CRC specimens using real-time quantitative polymerase chain reaction (RTq-PCR), which demonstrated that miR-381 was significantly downregulated in CRC and correlated with distant metastasis and tumor, node, and metastasis (TNM) stage. Functional study revealed that restoration of miR-381 significantly inhibited the invasion, migration, and epithelial–mesenchymal transition (EMT) of CRC cells. Luciferase reporter assay validated that Twist1, an important EMT inducer, was a direct target of miR-381, and rescued Twist1 attenuated the function of miR-381 in CRC cells. Correlation analysis also revealed an inverse correlation between miR-381 and Twist1 expression levels in CRC specimens. Taken together, our results highlight the significance of miR-381/Twist1 interaction in the development and progression of CRC, and suggest that restoration of miR-381 may be a potential therapeutic strategy for the patients with CRC.

MiR-1180 promotes apoptotic resistance to human hepatocellular carcinoma via activation of NF-κB signaling pathway

Apoptosis resistance in human hepatocellular carcinoma (HCC) is a significant factor in carcinogenesis. Therefore, understanding the molecular mechanisms involved in apoptosis resistance is crucial for developing anticancer therapies. Importantly, small non-coding microRNAs (miRNAs) have been reported as key biomarkers for detecting tumour onset and progression. In the present study, we demonstrate that miR-1180 is upregulated in HCC. Ectopic expression of miR-1180 has an anti-apoptotic effect in HCC, while miR-1180 inhibition increases cell apoptosis, both in vitro and in vivo. Moreover, our results show that miR-1180 directly targets key inhibitors of the nuclear factor (NF)-κB signaling pathway (i.e., OTUD7B and TNIP2) and the pro-apoptotic Bcl-2 associated death promoter (BAD) protein by post-transcriptional downregulation. Therefore, the anti-apoptotic function of miR-1180 in HCC may occur through NF-κB pathway activation via downregulation of its negative regulators. In conclusion, our study reveals the critical role of miR-1180 during apoptosis resistance in HCC.

Effect of junctional adhesion molecule-2 expression on cell growth, invasion and migration in human colorectal cancer

The junctional adhesion molecule (JAMs) family belongs to the immunoglobulin subfamily involved in the formation of tight junctions (TJ) in both endothelial and epithelial cells. Aberrant expression of JAM-2 is associated with cancer progression but little work has been carried out in discovering how this affects changes in cell behaviour. The present study aimed to examine the expression of JAM-2 in human colon cancer specimens and cell lines and its role in the development of colon cancer. JAM-2 expression in human colon cancer specimens (normal, n=75; cancer, n=94) and cell lines was analysed using quantitative real-time PCR and conventional RT-PCR. Colon cancer cells were stably transfected with a mammalian expression vector to overexpress JAM-2-Flag. The effect on growth, adhesion and migration following overexpression of JAM-2 was then investigated using in vitro models. TJ function was assessed using a trans-epithelial resistance assay (TER, with an EVOM voltammeter). JAM-2 was lowly expressed in colon cancer cells such as RKO, HT115. JAM-2 overexpression in RKO cells (RKO-JAM-2) and HT115 cells (HT115-JAM-2) showed retarded adhesion (P<0.05). An in vivo tumour model showed that RKO-JAM-2 had significantly reduced growth (P<0.05), invasion (P<0.05) and migration (P<0.05) as well as in HT115-JAM-2, except on proliferation and migration. Expression of JAM-2 resulted in a significant increase in TER and decrease in permeability of polarized monolayers (P<0.05). Further analysis of JAM-2 transcript levels against clinical aspects demonstrated that the decreasing JAM-2 expression correlated to disease progression, metastasis and poor survival. Taken together, JAM-2 may function as a putative tumour suppressor in the progression and metastasis of colorectal cancer.

MiRNA-21 Expression Decreases from Primary Tumors to Liver Metastases in Colorectal Carcinoma

Objective

Metastasis is the major cause of death in colorectal cancer patients. Expression of certain miRNAs in the primary tumors has been shown to be associated with progression of colorectal cancer and the initiation of metastasis. In this study, we compared miRNA expression in primary colorectal cancer and corresponding liver metastases in order to get an idea of the oncogenic importance of the miRNAs in established metastases.

Methods

We analyzed the expression of miRNA-21, miRNA-31 and miRNA-373 in corresponding formalin-fixed paraffin-embedded (FFPE) tissue samples of primary colorectal cancer, liver metastasis and healthy tissues of 29 patients by quantitative real-time PCR.

Results

All three miRNAs were significantly up-regulated in the primary tumor tissues as compared to healthy colon mucosa of the respective patients (p < 0.01). MiRNA-21 and miRNA-31 were also higher expressed in liver metastases as compared to healthy liver tissues (p < 0.01). No significant difference of expression of miRNA-31 and miRNA-373 was observed between primary tumors and metastases. Of note, miRNA-21 expression was significantly reduced in liver metastases as compared to the primary colorectal tumors (p < 0.01).

Conclusion

In the context of previous studies demonstrating increased miRNA-21 expression in metastatic primary tumors, our findings raise the question whether miRNA-21 might be involved in the initiation but not in the perpetuation and growth of metastases.

G9a is essential for EMT-mediated metastasis and maintenance of cancer stem cell-like characters in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a particularly aggressive cancer with poor prognosis, largely due to lymph node metastasis and local recurrence. Emerging evidence suggests that epithelial-to-mesenchymal transition (EMT) is important for cancer metastasis, and correlated with increased cancer stem cells (CSCs) characteristics. However, the mechanisms underlying metastasis to lymph nodes in HNSCC is poorly defined. In this study, we show that E-cadherin repression correlates with cancer metastasis and poor prognosis in HNSCC. We found that G9a, a histone methyltransferase, interacts with Snail and mediates Snail-induced transcriptional repression of E-cadherin and EMT, through methylation of histone H3 lysine-9 (H3K9). Moreover, G9a is required for both lymph node-related metastasis and TGF-β-induced EMT in HNSCC cells since knockdown of G9a reversed EMT, inhibited cell migration and tumorsphere formation, and suppressed the expression of CSC markers. Our study demonstrates that the G9a protein is essential for the induction of EMT and CSC-like properties in HNSCC. Thus, targeting the G9a-Snail axis may represent a novel strategy for treatment of metastatic HNSCC.

Downregulation of β3 integrin by miR-30a-5p modulates cell adhesion and invasion by interrupting Erk/Ets‑1 network in triple-negative breast cancer

Integrins are adhesion receptors involved in bidirectional signaling and are crucial for various cellular responses during normal homeostasis and pathological conditions, such as cancer progression and metastasis. In the present study, we demonstrated that blockage of β3 integrin-mediated cell- extracellular matrix interactions restrained triple-negative breast cancer (TNBC) growth, and elevated β3 integrin can trigger the rewiring of Erk/Ets-1 signaling pathways, thereby enhancing cell growth and invasion. Ectopic expression of miRNA has been implicated in the deregulation of integrin expression and activity, blocking of cancer tumor development and progression, and acquisition of metastatic phenotype. miR-30a-5p expression has been implicated in the progression of breast cancer. Overexpression of miR-30a-5p suppressed the proliferation, migration and invasion of breast cancer cells. On the contrary, inhibition of miR-30a-5p promoted the proliferation, migration, and invasion of TNBC cells by suppressing the expression of ERK/Ets-1 signal. An inverse correlation was found between the mRNA expressions of miR-30a-5p and β3 integrin in TNBC samples. Furthermore, bioinformatics analysis revealed the putative miR-30 binding sites in the 3'-UTR of β3 integrin. Results of luciferase assay revealed a strong repression of luciferase activity after transfection with miR‑30a-5p and wild-type 3'-UTR of β3 integrin. In TNBC cells, miR-30a-5p promoted an epithelial phenotype and suppressed invasion by specifically targeting β3 integrin subunit to subsequently interdict the β3 integrin/Erk/Ets-1 network.

Exosomes derived from SW480 colorectal cancer cells promote cell migration in HepG2 hepatocellular cancer cells via the mitogen-activated protein kinase pathway

Exosomes are membrane-derived extracellular vesicles that have recently been recognized as important mediators of intercellular communication. In the present study, we investigated the effects of exosomes derived from SW480 colorectal cancer cells in recipient HepG2 hepatocellular cancer cells. We demonstrated that SW480-derived exosomes were taken up by the recipient HepG2 cells via dynamin-dependent endocytosis and were localized to the HepG2 lysosomes. In addition, SW480-derived exosomes induced the phosphorylation of extracellular signal-regulated kinase (ERK)1/2 following their uptake into HepG2 cells. Of note, these changes occurred during the early phase after exosome treatment. Furthermore, SW480-derived exosomes promoted the migration of recipient HepG2 cells in a wound-healing assay, which was suppressed by pretreatment with U0126, an upstream inhibitor of ERK1/2. These results indicated that SW480-derived exosomes activated a classical mitogen-activated protein kinase pathway in recipient HepG2 cells via dynamin-dependent endocytosis and subsequently enhanced cell migration by ERK1/2 activation. Our results provide new insights into the regulation of cellular functions by exosomes.

MicroRNAs: Clinical Relevance in Colorectal Cancer

Colorectal cancer is one of the most common cancer diagnoses and causes of mortality worldwide. MicroRNAs are a class of small, non-coding regulatory RNAs that have shown strong associations with colorectal cancer. Through the repression of target messenger RNAs, microRNAs modulate many cellular pathways, such as those involved in cell proliferation, apoptosis, and differentiation. The utilization of microRNAs has shown significant promise in the diagnosis and prognosis of colorectal cancer, owing to their unique expression profile associations with cancer types and malignancies. Moreover, microRNA therapeutics with mimics or antagonists show great promise in preclinical studies, which encourages further development of their clinical use for colorectal cancer patients. The unique ability of microRNAs to affect multiple downstream pathways represents a novel approach for cancer therapy. Although still early in its development, we believe that microRNAs can be used in the near future as biomarkers and therapeutic targets for colorectal cancer.

An in vivo molecular response analysis of colorectal cancer treated with Astragalus membranaceus extract

The fact that many chemotherapeutic drugs cause chemoresistance and side effects during the course of colorectal cancer treatment necessitates development of novel cytotoxic agents aiming to attenuate new molecular targets. Here, we show that Astragalus membranaceus (Fischer) Bge. var. mongolicus (Bge.) Hsiao (AM), a traditional Chinese medicine, can inhibit tumor growth in vivo and elucidate the underlying molecular mechanisms. The antitumor effect of AM was assessed on the subcutaneous tumors of human colorectal cancer cell line HCT116 grafted into nude mice. The mice were treated with either water or 500 mg/kg AM once per day, before being sacrificed for extraction of tumors, which were then subjected to microarray expression profiling. The gene expression of the extraction was then profiled using microarray analysis. The identified genes differentially expressed between treated mice and controls reveal that administration of AM suppresses chromosome organization, histone modification, and regulation of macromolecule metabolic process. A separate analysis focused on differentially expressed microRNAs revealing involvement of macromolecule metabolism, and intracellular transport, as well as several cancer signaling pathways. For validation, the input of the identified genes to The Library of Integrated Network-based Cellular Signatures led to many chemopreventive agents of natural origin that produce similar gene expression profiles to that of AM. The demonstrated effectiveness of AM suggests a potential therapeutic drug for colorectal cancer.

miR-590-3p suppresses cancer cell migration, invasion and epithelial-mesenchymal transition in glioblastoma multiforme by targeting ZEB1 and ZEB2

Invasion and migration of glioblastoma multiforme (GBM) is a multistep process and an important phenotype that causes this disease to invade surrounding tissues in the brain. The purpose of this study was to determine the role of miR-590-3p in regulation of epithelial mesenchymal transition (EMT) and metastasis of GBM cells. Expression levels of miR-590-3p in 15 GBM specimens with adjacent tissues and five GBM cell lines were assessed by quantitative RT-PCR. We found that miR-590-3p was down-regulated in detected GBM tissue samples and all of the GBM cell lines. In addition, Ectopic expression of miR-590-3p suppressed and miR-590-3p-in promoted EMT, migration, and invasion in U87MG and A172 cells. Bioinformatics coupled with luciferase and Western blot assays also revealed that miR-590-3p inhibited expression of ZEB1 and ZEB2, which are master regulators of tumor metastasis. Our study first indicates that miR-590-3p functions as a suppressor of GBM EMT and metastasis by targeting ZEB1 and ZEB2, and it may be a therapeutic target for metastatic GBM.

MiR expression profiles of paired primary colorectal cancer and metastases by next-generation sequencing

MicroRNAs (miRs) have been recognized as promising biomarkers. It is unknown to what extent tumor-derived miRs are differentially expressed between primary colorectal cancers (pCRCs) and metastatic lesions, and to what extent the expression profiles of tumor tissue differ from the surrounding normal tissue. Next-generation sequencing (NGS) of 220 fresh-frozen samples, including paired primary and metastatic tumor tissue and non-tumorous tissue from 38 patients, revealed expression of 2245 known unique mature miRs and 515 novel candidate miRs. Unsupervised clustering of miR expression profiles of pCRC tissue with paired metastases did not separate the two entities, whereas unsupervised clustering of miR expression profiles of pCRC with normal colorectal mucosa demonstrated complete separation of the tumor samples from their paired normal mucosa. Two hundred and twenty-two miRs differentiated both pCRC and metastases from normal tissue samples (false discovery rate (FDR) <0.05). The highest expressed tumor-specific miRs were miR-21 and miR-92a, both previously described to be involved in CRC with potential as circulating biomarker for early detection. Only eight miRs, 0.5% of the analysed miR transcriptome, were differentially expressed between pCRC and the corresponding metastases (FDR <0.1), consisting of five known miRs (miR-320b, miR-320d, miR-3117, miR-1246 and miR-663b) and three novel candidate miRs (chr 1-2552-5p, chr 8-20656-5p and chr 10-25333-3p). These results indicate that previously unrecognized candidate miRs expressed in advanced CRC were identified using NGS. In addition, miR expression profiles of pCRC and metastatic lesions are highly comparable and may be of similar predictive value for prognosis or response to treatment in patients with advanced CRC.