Mutation of the transforming growth factor-β typeⅡ receptor gene in sporadic colorectal cancers with microsatellite instability

AIM: To determine the relationship between the mutation of the RII gene and RER status in the tumorigenesis of sporadic colorectal cancer. METHODS: We screened RER status and mutation of the RII gene from 50 sporadic colorectal cancers (19 in the proximal colon, 31 in the distal colorectum). RESULTS: RER was found in 13 cases (8 in the proximal colon, 5 in the distal colorectum), and 5 of them showed mutations of the RII gene. All 5 cancers carrying a TGF-β RII gene mutation showed RER+, but there wasn't any mutation of RII gene in RER(-) cases. Four of 5 RII mutation were located at the cecum. CONCLUSION: These data indicate that the TGF- βRII gene is a major target of microsatellite instability and mutation of the RII gene play an important role in carcinogenesis of sporadic colorectal cancer with microsatellite instability , especially at the cecum.     

Sensitivity of different human colorectal tumor cell lines to commonly used chemotherapeutic drugs in vitro

AIM: To observe the antitumor effect of 5 commonly used chemotherapeutic drugs on 11 human colorectal cancer cell lines in vitro. METHODS: CCK-8 method was used to determine the growth inhibitory effects of 5 antitumor drugs, which were expressed as the half growth inhibitory concentration (IC50) and sensitivity index IC50/PPC (peak plasma concentration) on 11 human colorectal cancer cell lines. The expression variations of heat-shock protein 27 (HSP27) and HSP70 at protein levels in human colorectal tumor cell lines treated with different chemotherapeutic drugs were observed by Western blotting. RESULTS: All the 11 colorectal cancer cell lines were sensitive to 5-fluorouracil (5-FU) and oxaliplatin (OHP) without drug resistant. Five colorectal cancer cell lines were sensitive to mitomycin (MMC), while the other 6 cell lines were moderately sensitive. Ten colorectal cancer cell lines except SW1116 were sensitive to docetaxel (DXL), while SW1116 cells were resistant to DXL. Nine colorectal cancer cell lines except LS174T and SW1116 were moderately sensitive to irinotecan (IFL), and SW1116 cells were also resistant to IFL, while LS174T cells were sensitive to IFL. After treated with the antitumor drugs, HSP27 was up-regulated in HCT116 cells and SW480 cells, while the expression of HSP70 didnt change. CONCLUSION: LS174T cells are multidrug-sensitive, while SW1116 cells are multidrug-resistant. 5-FU and OHP are the wide-spectrum anti-colorectal cancer drugs. Determining the sensitivity to chemotherapeutic drugs and the expression level of HSP27 can improve the accuracy in drug selection.     

Effect of long non-coding RNA MEG3 on invasion and migration of colorectal cancer cells

AIM: To investigate the expression of long non-coding RNA maternally expressed gene 3(MEG3) in colorectal cancer(CRC) cells, and to observe the effect of MEG3 on the invasion and migration of CRC cells. METHODS: The levels of MEG3 in human normal colon cell NCM460 and CRC cells SW48 and LoVo were detected by real- time PCR. MEG3 was over-expressed by plasmid transfection, and the effects of MEG3 on the invasion and migration of SW48 and LoVo cells were analyzed by Transwell assay and wound healing assay. The expression of matrix metalloproteinase(MMP) family proteins was determined by Western blotting. RESULTS: The level of MEG3 was down-regulated in CRC cells compared with normal colon cell NCM460. The invasion and migration of CRC cells were reduced after MEG3 over-expression. Transwell invasion and migration assays showed that the numbers of transmembrane SW48 and LoVo cells were smaller in MEG3 over-expression group than control group(CONCLUSION: The expression of MEG3 is down-regulated in CRC cells. Over-expression of MEG3 inhibits the invasion and migration of CRC cells. TIMP-2, MMP-2 and MMP-9 might play an important role in this regulation.     

Effects of heterogously-expressed RON receptor tyrosine kinase on motile/invasive ability of human colorectal cancer cell line RKO

AIM: To investigate the roles of overexpression of RON receptor tyrosine kinase in motile/invasive ability of human colorectal cancer cell line RKO. METHODS: A eucaryotic expression vector pDR2 containing full-length wt-RON cDNA was transfected into the colorectal cancer cell line RKO and a stable expression clone was obtained. The motile/invasive ability was tested by wound healing test and the transwell migration assay. The expression of E-cadherin was measured by Western blotting. RESULTS: Motile ability of transfected RKO was greatly promoted by transwell chemotaxis assay (P<0.01). The wound healing time showed statistical difference as of (42.50±4.12) h, (69.50±2.52) h and (70.50±3.42) h, respectively in transfected group, untransfected group and vector control group. After knocking down RON by siRNA, the motile became less than that in control group (P<0.01). E-cadherin expression in transfected RKO was decreased significantly due to pDR2-wt-RON transfection. CONCLUSIONS: Overexpression of wt-RON led to the decrease in expression of E-cadherin and decreased cancer cell-cell adhension. At the same time, migration/invasion ability was promoted. Taken together, abnormal accumulation of RON might play potential roles in invasion/metastasis of colorectal cancer. RNAi can block motile/invasion ability mediated by RON.     

Expression and clinical significance of Bmi-1 in colorectal cancer

AIM:This study was to investigate the expression and significance of Bmi-1 in colorectal carcinoma (CRC), and to explore the effect of Bmi-1 on Ki67 expression in human CRC.METHODS:The samples from sixty CRC, thirty adenomas and twenty normal colorectal mucosal tissues were used in this study.The expression of Bmi-1 protein was detected by immunohistochemistry.The clinicopathological features and survival rate of patients were also analyzed.RESULTS:The overexpression of Bmi-1 was respectively 25.0％, 6.7％and 0% in CRC and adenomas as well as normal colorectal mucosal tissues.The results showed that the expression of Bim-1 was significantly higher in CRC, compared with that in adenomas and normal colorectal mucosal tissues (P<0.05).The overexpression of Bmi-1 protein in CRC was obviously associated with distant metastasis and TNM stage (P<0.05), but not with gender, age, tumor size, tumor site, histological type, differentiation degree and lymph node metastasis (P>0.05).Kaplan-Meier survival analysis showed that the overexpression of Bmi-1 reduced significantly survival of CRC patients (P<0.05).No statistical relation between expression of Bmi-1 and Ki67 in CRC was observed.CONCLUSION:The overexpression of Bmi-1 protein is significantly correlated with tumorigenesis, metastasis and prognosis of CRC.Bmi-1 might be regarded as a parameter in evaluating prognosis of CRC.     

Expression of phosphorylated MEK2 (Thr394) in colorectal cancer and its clinical implication

AIM:To analyze the phosphorylation of Thr394 residue of mitogen extracellular kinase 2 (MEK2) protein in human colorectal tissues and its clinical significance. METHODS:Formalin-fixed, paraffin-embedded human colorectal tissue specimens were immunostained with the antibody against p-MEK2 (Thr394). The expression levels of p-MEK2 in normal mucosa (n=24), adenoma (n=24) and adenocarcinoma (n=96) of colorectum were compared. Another group of colorectal adenocarcinoma samples (n=417) was used to analyze the expression of p-MEK2 (Thr394) and its relationship with clinicopathological parameters and overall survival. RESULTS:The expression level of p-MEK2 (Thr394) in normal mucosa was 100%, in colorectal adenomas was 66.7% and in colorectal adenocarcinoma was 198%, showing the tendency of decrement and statistically significant differences. No significant correlation between the expression level of p-MEK2 (Thr394) and the clinicopathological parameters including sex, age, body mass index, differentiation degree, T stage, N stage, TNM stage, hepatic metastasis and mutation of K-ras was observed. Moreover, Kaplan-Meier analysis showed that the expression level of p-MEK2 (Thr394) and the prognosis of colorectal cancer had no significant correlation. CONCLUSION: Reduction of p-MEK2 (Thr394) expression occurs during colorectal tumorigenesis. The phosphorylation of Thr394 residue in MEK2 may play an important role in the development of colorectal cancer.     

Screening of differentially expressed genes in colorectal cancer based on TCGA database and verification of novel gene CCDC78

AIM To explore novel genes closely related to the prognosis of colorectal cancer through bioinformatics analysis of RNA sequencing (RNA-Seq） data of gene expression profile in large samples of colorectal cancer tissues from The Cancer Genome Atlas (TCGA) database, and to validate the new genes and study their functions. METHODS The RNA-Seq data were downloaded from TCGA database to screen differentially expressed genes, R-survival package was used to carry out survival analysis of differentially expressed genes to screened out genes related to prognosis of colorectal cancer, and the most significantly up-regulated genes that have not been reported in cancer studies were selected for further verification. RT-qPCR was employed to detect mRNA expression of these novel genes in human colon cancer cell lines and human colorectal cancer tissues. The colon cancer cell line with stable silencing of the novel gene expression was constructed by transfection of lentivirus vector, and its viability, migration and invasion were detected by CCK-8 assay and Transwell assay. RESULTS (1) A total of 4 017 differentially expressed genes were found in the gene expression profile of the colorectal cancer samples. Kaplan-Meier survival analysis showed that 69 genes were closely related to poor prognosis in patients with colorectal cancer, 36 of which were up-regulated, and 11 of these 36 genes have not been reported in cancer studies. (2) The mRNA expression of the top 3 up-regulated genes CCDC78, PGGHG and TSPEAR of the 11 genes was significantly increased in colon cancer cell lines, and the expression of CCDC78 mRNA was also up-regulated in colorectal cancer tissues. (3) CCDC78 gene silencing significantly suppressed the viability, migration and invasion of colon cancer cells (P<0.01). CONCLUSION Bioinformatics analysis based on TCGA database is helpful to discover nov?el genes related to prognosis of colorectal cancer, and CCDC78 may be a novel oncogene associated with poor prognosis of colorectal cancer.     

Progress on DAB2IP gene

Human DAB2 interaction protein (DAB2IP) is a novel member of Ras GTPase-activating protein family. It interacts directly with disabled-2 protein (DAB2/DOC2) which suppresses growth of cancers derived from different tissues, including mammary, prostate and ovarian cancers. DAB2IP was identified as an immediate downstream effector mediated by DAB2/DOC2. DAB2IP and DAB2/DOC2 form a unique protein complex that has a negative regulatory effect on the Ras-mediated signal pathway. It is demonstrated that DAB2IP is a tumor suppressor gene inactivated by methylation in several cancers. This article reviews the structure and biological functions of DAB2IP gene as well as its potential roles in carcinogenesis and evolution.     

Up-regulation of microRNA-187* inhibits proliferation of human colon cancer cell line HCT116

AIM:To investigate the expression of microRNA-187* (miR-187*) in human colon cancer cell lines and normal colon tissues, and to determine the effects of miR-187* up-regulation on the proliferation and cell cycle of human colon cancer cell line HCT116. METHODS:The expression profiling of miRNAs in 3 colorectal adenocarcinoma samples and their matched normal tissue samples was performed using miRNA microarray chip. Total RNA was isolated from 8 colon cancer cell lines and 10 normal colon tissues. The miR-187* level was detected by Taqman real-time RT-PCR. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI-1), the possible target of miR-187*, was also detected. Synthetic miR-187* mimics were transfected into HCT116 cell line by LipofectamineTM 2000. The mRNA expression of miR-187* and BMI-1 in HCT116 cell line was measured by real-time RT-PCR. Cell growth and cell cycle were assayed by MTS method and flow cytometry. RESULTS:miR-187* was found to be differentially expressed between colorectal adenocarcinoma and normal tissues. The expression of miR-187* in 8 colon cancer cell lines was down-regulated, while BMI-1 mRNA was up-regulated. Compared with blank control group, miR-187* expression was remarkably increased after transfection with miR-187* mimics, and ectopic expression of miR-187* significantly inhibited the mRNA expression of BMI-1. The cell growth was inhibited in miR-187* mimics group, and proliferating cell nuclear antigen (PCNA) mRNA expression was decreased. The cells at G2/M phase in miR-187* mimics group were significantly increased. CONCLUSION: miR-187* is down-regulated in human colon cancer cell lines. Up-regulation of miR-187* not only inhibits the proliferation but also influence the cell cycle of HCT116 cells, which might act as a tumor suppressor in colorectal cancer by inhibiting the expression of BMI-1.     

Effects of BCL-3 gene silencing on the proliferation and drug sensitivity of human colorectal cancer cell line RKO with high expression of BCL-3

AIM：To construct lentiviral vectors for RNA interference (RNAi) of BCL-3 gene, and to detect the changes of biological behaviors and drug sensitivity of colorectal cancer cells after BCL-3 gene silencing. METHODS：The expression of BCL-3 in five human colorectal cancer cell lines was detected by RT-PCR and Western blotting. Lentiviral vectors for RNAi of BCL-3 gene were constructed and transfected into the human colorectal cancer cell line with high expression of BCL-3, and then the silencing effect was detected by Western blotting. After BCL-3 gene silencing, the change of cell proliferation was detected by MTT assay and soft agar colony formation assay, and the change of drug sensitivity was detected by MTT assay. RESULTS：BCL-3 was highly expressed in human colorectal cancer cell line RKO. Lentiviral vectors for RNAi of BCL-3 gene were successfully constructed, and Western blotting showed that BCL-3-shRNA2 could efficiently inhibit the expression of BCL-3 protein in RKO cells. After BCL-3 gene silencing, the proliferation ability and colony formation rate of RKO cells were decreased, and the median inhibitory concentration of oxaliplatin for RKO cells also decreased significantly. CONCLUSION: Inhibition of BCL-3 gene expression decreases the proliferation ability of human colorectal cell line RKO with high expression of BCL-3, and enhances the sensitivity of RKO cells to oxaliplatin.     

Methylation of TIMP-3 gene and their relationships with their clinical-pathological characteristics of colorectal cancers

AIM: To investigate whether methylation of the TIMP-3 gene is associated with clinical-pathological characteristics, recurrence and metastasis of the colorectal cancer. METHODS: Nest methylation specific PCR (nMSP) and RT-PCR techniques were used to detect methylation of TIMP-3 gene and its mRNA expression in the colorectal cancer specimen and adjacent non-cancerous tissues. RESULTS: The expression of TIMP-3 mRNA in tumor tissues was distinctly reduced (P<0.01). The expression of TIMP-3 mRNA in those without lymph node metastasis was higher than those with lymph node metastasis (P<0.01). The patients with Duke's C, D and lymph node metastasis were more to contain methylated TIMP-3 compared to those with Duke's A, B and no lymph node metastasis (P<0.05). Statistical differences in pathological characteristics such as tumor site, Duke's stage, histological differentiation and type between TIMP-3 methylation positive group and negative group were observed (P<0.05). CONCLUSION: Methylation of the TIMP-3 gene promoter usually occurs in the proximal site, infiltrating type, poor cellular differentiation, lymph node metastasis and advanced stage of colorectal cancers patients.     

Research advance in molecular characteristics of human stanniocalcin 1

Stanniocalcin (STC) is a glycoprotein hormone that was firstly found in bony fish. The related human proteins, STC1and STC2, are expressed in a wide variety of tissues. STC1 is involved in calcium and phosphate homeostasis, and plays important roles in carcinogenesis. This article reviews the data currently available regarding the human STC1, and discusses the roles they may play in normal physiology and in cancers.     

Apoptosis of colorectal cancer cells transfected with human mutant p27

AIM: To study the inducing effect of human mutant p27 gene on apoptosis of the colorectal cancer cells. METHODS: The recombinant adenovirus Ad-p27mt was constructed to infect the colorectal cancer cell SW480. The inducing effect of Ad-p27mt on apoptosis in colorectal cancer cells was measured by flow cytometry, DNA fragment analysis and TUNEL method. RESULTS: Ad-p27mt was successfully constructed. When the multiplicity of infection (MOI) was ≥50, the infection efficiency reached 100%. After 24 h of infection, there was an apoptotic hypodiploid peak observed by flow cytometry before G1 and there were apoptotic characteristic bands in the DNA electrophoresis. The apoptotic index detected by TUNEL method was 82.6±3.2 (Ad-p27mt group) and 5.0±3.5 (control group), respectively, the difference of which was significant (P<0.01). CONCLUSION: Human mutant p27 gene transfection effectively induces apoptosis in the colorectal cancer cells.     

Identification of tumor antigen epitopes by MHC-I/peptide binding prediction and immunological experiments

AIM:To establish the methods to identify immune epitopes of tumor antigens restricted by human leukocyte antigen (HLA) alleles frequent in the Chinese population for the isolation and identification of tumor-specific T cells and the cloning of tumor antigen-specific T-cell receptor gene. METHODS:Three cancer/testis antigens NY-ESO,MAGE-A1 and KK-LC-1 were selected as the model antigens to predict the MHC-I binding peptides by major histocompatibility complex (MHC)-peptide binding prediction software. The HLA alleles of healthy volunteers were determined by PCR. The predicted epitopes restricted by HLA-A*11:01 and HLA-B*46:01 of the volunteers were selected for the long peptide design. ELISPOT and flow cytometry were used to analyze the interferon-γ (IFN-γ) spots of the activated T-cells and the up-regulation of CD137 to verify the effectiveness of peptides for T-cell-specific stimulation. We selected long peptides with the best response to verify short peptides. RESULTS:Three cancer/testis antigens containing many strong binding epitopes restricted by 35 HLA alleles common in Chinese population were found. It was found that the predicted epitopes were not equally distributed in the protein sequences. KK-LC-1 antigen was selected for further study. The 2 long peptides stimulated T-cell activation:the release of IFN-γ and up-regulation of CD137 molecules by T cells of the volunteers with the matched HLA alleles. The short peptides worked better than the long peptides.CONCLUSION:Tumor antigen epitopes are quickly identified by MHC/peptide binding prediction and T-cell stimulation analysis. According to the reaction of the long peptide, the short peptide is synthesized to verify the precise epitope. This study provides a new way to determine tumor antigen epitopes quickly.     

Expression and significance of T-cell immunoglobulin and ITIM domain in colorectal cancer

AIM: To study the expression and clinical significance of T-cell immunoglobulin and ITIM domain (TIGIT) in colorectal cancer. METHODS: The patients with colorectal cancer (n=80) from January 2016 to June 2018 were selected. The expression of TIGIT and CD155 in the colorectal cancer tissues and adjacent normal tissues were detected by immunohistochemical staining method. The expression of TIGIT and CD155 was also determined by Western blot and ELISA. RESULTS: The positive expression rates of TIGIT and CD155 were 78.8% (63/80) and 83.8% (67/80) in the colorectal cancer tissues, significantly higher than that in the paracancerous tissues of 8.8% (7/80) and 18.8% (15/80), respectively (P<0.05). There was a positive correlation between TIGIT and CD155 expression (r=0.867, P<0.01). The expression levels of TIGIT and CD155 were increased as the stage evolved. The positive rates of TIGIT and CD155 in the colorectal cancer tissues were correlated with the degree of differentiation, pathological stage and lymph node metastasis (P<0.05). CONCLUSION: TIGIT and CD155 are correlated with the occurrence and development of colorectal cancer, and can be used as one of the prognostic indicators of colorectal cancer.     

Influence of human mutant p27 gene on the biological behaviors of colorectal cancer cells

AIM: To observe the influence of human mutant p27 gene (p27mt) on the growth and so as to investigate the function and mechanism of p27mt in gene therapy for colorectal cancer.METHODS: Colorectal cancer cell line SW480 was infected with recombinant replication defective adenovirus Ad-p27mt,and expression of p27mt protein was detected by Western blotting.The inhibitory effect of p27mt on SW480 and cell cycle were determined by flow cytometry,and DNA fragment was analyzed to identify the occurrence of apoptosis.RESULTS: After transfected with Ad-p27mt,p27 protein was highly expressed in SW480 cells.77.96% colorectal cancer cells were blocked in phase G₀/G₁,while in Ad-LacZ group and blank control group,27.57% and 25.29% cells were blocked in the same phase,respectively.Growth curve showed Ad-p27mt had an obviously inhibitory effect on the growth of SW480 cells.DNA fragment assay demonstrated that p27mt was able to induce the apoptosis of colorectal cancer cells.CONCLUSION: p27mt has an obvious blocking effect on colorectal cancer cell cycle,and most cells are blocked in phase G₀/G₁.This blockage is related with the growth inhibition and apoptosis induced by p27mt.     

Recent advances in relationship between diversity of gut microbiota and health

Trillions of microbes inhabit the human intestine, forming a complex microecological community. It has been found that the gut microbiotas contribute nutrients and energy to the host, and they are also involved in the occurrence and development of human diseases. With the continuous development of related research, there is increasing evidence suggesting a close relationship between gut microbiota and human diseases. The discovery of this relationship affects the development of modern health care individually. In this review, we focus on the influence factors to the diversity of gut microbiota, which has influences on colorectal cancer, aging, obesity, immunity, drug effects and malnutrition.