microRNAs (miRNAs) are endogenous, small noncoding RNA molecules discovered in animals, plants and viruses. They play a critical role in developmental and physiological processes and are implicated in the pathogenesis of many human cancers. Presently, human cancer, including colorectal cancer, is recognized as both a genetic and epigenetic disease. Changes induced by miRNAs are considered as epigenetic changes. Experiments were largely performed to analyze the colorectal microRNAome and bio-networking involving miRNAs. This review focuses on recent advances in colorectal miRNA expression profiles. Further, we discuss the regulatory network of miRNAs in the initiation and carcinogenesis of colon cancer in order to open up an avenue of anticancer therapy based on the epigenetic regulation by miRNAs.
Animals ; Colonic Neoplasms ; genetics ; Epigenesis, Genetic ; genetics ; Humans ; MicroRNAs ; genetics

Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; Colonic Neoplasms/genetics* ; Glucosephosphate Dehydrogenase/genetics* ; Humans ; MicroRNAs/genetics*

OBJECTIVETo investigate the inhibiting impact of 5'-deoxy-5-fluorouridine (5'-DFUR) on human colon carcinoma cell line LOVO after transfection of thymidine phosphorylase (TP) cDNA.

METHODSTP cDNA was transfected into human colon carcinoma cell line LOVO with lentiviral vector pLenti6.3_MCS_IRES2-EGFP, and the transfection efficiency was analyzed by flow cytometry. TP mRNA and protein expressions were detected by RT-PCR and Western blotting respectively. The IC50 of 5'-DFUR on TP-transfected LOVO and parental cell were evaluated by MTT assay. The volumes of 5-FU converted from 5'-DFUR in media, where TP-transfected and parental LOVO were cultured, were detected by HPLC.

RESULTSThe stable transfectants passed 5 generations were obtained and the transfection rate was 95%. Compared with parental cell, the RQ values of mRNA expression in TP-transfected LOVO was (282.5±86.8) folds higher significantly (P<0.01), also the TP protein expression of TP-transfected LOVO was obviously up-regulated as compared to parental cells. The IC50 value of 5'-DFUR of TP-transfectants was (1087.7±89.1) μmol/L, less than (1607.3±56.8) μmol/L of parental cells significantly (P<0.01), while there was no significant difference between parental cells and vector-transfectants [(1699.5±38.7) μmol/L, P>0.05]. HPLC revealed that when medium was added with 0, 500, 1000, and 2000 μmol/L of 5'-DFUR respectively, 0, 2.10, 3.13, and 7.19 μmol/L of 5-FU was found in the parental cells culture, while 0, 22.16, 30.94 and 40.02 μmol/L of 5-FU was found in TP-transfectants culture, but no 5-FU was found in the vector-transfectants culture.

CONCLUSIONTP cDNA transfection into LOVO can up-regulate the TP mRNA and protein expressions, increase the 5-FU converted from 5'-DFUR, and enhance the cytotoxic effect of 5'-DFUR on the LOVO cells.

Cell Line, Tumor ; Colonic Neoplasms ; pathology ; DNA, Complementary ; genetics ; Floxuridine ; pharmacology ; Humans ; Thymidine Phosphorylase ; genetics ; Transfection

OBJECTIVETo investigate miR-146a expression in colonic cancer and its clinical implications.

METHODSQuantitative real-time PCR was employed to detect the levels of miR-146a expression in colonic cancer tissues, pair-matched adjacent normal tissues and different colonic cancer cell lines. MTT essay was used to evaluate the proliferation of colonic cancer SW260 cells transfected with miR-146a mimics, and the cell cycle and apoptosis of the cells were analyzed with flow cytometry.

RESULTSCompared with the normal tissues, 38 of the 43 colonic cancer samples showed down-regulated miR-146a expression, which was associated with poor tumor differentiation. The expression of miR-146a in the tumor tissues was significantly correlated with tumor size and clinical stages. The patients with high miR-146a expression levels had significantly longer total survival time than those with low expression of miR-146a. In SW260 cell cultures, transfection with miR-146a mimics significantly inhibited cell growth (P<0.05) and increased the cell apoptosis rate (11.9% vs 5.9%) but produced no obvious effect on cell cycle.

CONCLUSIONSmiR-146a may serve as a potential therapeutic target for colonic cancer for its role in inhibiting colonic cancer cell proliferation.

Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; Colonic Neoplasms ; genetics ; pathology ; Humans ; MicroRNAs ; genetics

Mismatch repair (MMR) system is one form of DNA repair mechanisms, which plays an important role in rectifying the mismatch of base pairs, reducing gene mutations and keeping genome stability. Abnormal expression of MMR regulated by miRNA is closely related to the development of colon cancer. Functional defects of MMR (dMMR) with particular clinical characteristics can be used as a potential prognostic and predictive biomarker. This article reviews the relation between MMR system, miRNA and colon cancer.
Colonic Neoplasms ; genetics ; DNA Mismatch Repair ; Humans ; MicroRNAs ; genetics ; Mutation ; Prognosis

Objective To identify immune-related molecular markers in an attempt to predict prognosis of colon adenocarcinoma (COAD). Methods Immune related genes (IREGs) was analyzed based on the TCGA database. Weighted gene co-expression network analysis (WGCNA) and Cox regression analysis were used to establish risk models. According to the median risk score, COAD patients were divided into high risk and low risk groups. The prognostic difference were compared between the two groups. The function of the model was validated using GEO. Results A total of 1015 IREGs was obtained. The established model consisted of three genes: RAR related orphan receptor C (RORC), leucine-rich repeat Fli-I-interacting protein 2 (LRRFIP2) and lectin galactoside-binding soluble galectin 4 (LGALS4). The high-risk group had significantly poorer prognosis than low-risk group in the GEO database, and it was validated using a GEO database. Further analysis via univariate and multivariate Cox regression analyses revealed that risk model could function as independent prognostic factor for COAD patients. Conclusion The risk model based on IREGs can predict the prognosis of patients with COAD.
Humans ; Prognosis ; Adenocarcinoma/genetics* ; Colonic Neoplasms/genetics* ; Gene Expression Profiling ; Lectins

Adenocarcinoma ; genetics ; pathology ; Adenoma ; genetics ; pathology ; Colonic Polyps ; genetics ; pathology ; Colorectal Neoplasms ; genetics ; pathology ; Humans ; Microsatellite Instability ; Mutation ; Precancerous Conditions ; genetics ; pathology ; Proto-Oncogene Proteins B-raf ; genetics

OBJECTIVETo examine the differential expression of miRNAs in colon cancer tissues and matched tumor adjacent tissues.

METHODSDifferential expression of microRNAs in twenty paired human colon cancer tissues and adjacent tissues were detected by QPCR. miRNAs with significantly differential expression (fold change >2.4 and P<0.01) were screened to analyze their accumulation by Cluster analysis. Thus correlation of miRNA and other colon cancer-associated proteins was examined.

RESULTSExpressions of 17 miRNAs were significantly reduced in colon cancer tissues. Cluster analysis showed that miR763-3, miR451 and miR99a had similar expression. Plasma CK20 level was negatively correlated with miR100 (r=-0.948), miR152a-5p (r=-0.948), miR125b (r=-0.949), miR145 (r=-0.949) and miR145*(r=-0.949) (all P<0.05).

CONCLUSIONmiR145 and other 16 miRNAs may be used as diagnostic molecular markers of colon cancer, and miR100, miR125a-5p, miR125b, miR145 and miR145* may become the molecular markers of colon cancer lymph node metastasis.

Cluster Analysis ; Colonic Neoplasms ; genetics ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Genomics ; Humans ; Lymphatic Metastasis ; MicroRNAs ; genetics

Colonic Neoplasms ; genetics ; pathology ; CpG Islands ; genetics ; DNA Methylation ; Humans ; Polymerase Chain Reaction ; methods ; Sequence Analysis, DNA ; methods

OBJECTIVETo investigate the effect of siRNA targeting Livin and Survivin gene simultaneously on the proliferation and apoptosis of human colon cancer cells.

METHODSSiRNA recombinant expression vectors targeting Livin and Survivin gene simultaneously were constructed and transfected into human colon cancer cell line Lovo. The effects of siRNA recombinant expression vector on Lovo cells were detected by RT-PCR, Western blot, MTT reduction assay and flow cytometry.

RESULTSIt was confirmed by restriction endonuclease and sequence analysis that siRNA recombinant expression vector targeting Livin and Survivin gene simultaneously was constructed successfully. The suppressive rates of siRNA targeting Livin and Survivin gene simultaneously on Livin mRNA and protein expression were 27.9% and 22.3% respectively, and those on Survivin mRNA and protein expression were 32.2% and 40.9% respectively. The survival rate of cancer cells was decreased whereas the apoptotic rate was increased, but the coordinate repression was weaker than Livin and Survivin RNA interference alone.

CONCLUSIONSsiRNA targeting Livin and Survivin gene simultaneously can decrease the expression of Livin and Survivin gene, suppress cell proliferation and induce cell apoptosis in human colon cancer. The coordinate repression was weaker than Livin and Survivin RNA interference alone.

Adaptor Proteins, Signal Transducing ; genetics ; Apoptosis ; Cell Line, Tumor ; Colonic Neoplasms ; genetics ; pathology ; Humans ; Inhibitor of Apoptosis Proteins ; genetics ; Microtubule-Associated Proteins ; genetics ; Neoplasm Proteins ; genetics ; RNA, Small Interfering