Clinical significance and biological role of KLF17 as a tumour suppressor in colorectal cancer.

It has been reported that kruppel­like factor 17 (KLF17) acts as a tumour suppressor in several tissues and cancer cells, however, the molecular roles, the underlying mechanisms and clinical significance of KLF17 in colorectal cancer (CRC) have not been completely elucidated. In the present study, KLF17 protein expression was detected in 140 primary CRCs and paired adjacent non­tumour tissues using immunohistochemistry with tissue microarrays. The KLF17 mRNA expression was determined in 4 CRC cell lines and 20 pairs of the aforementioned tissues using reverse transcription quantitative polymerase chain reaction. The correlation between KLF17 expression and clinicopathologic characteristics was determined. Next, the functions of KLF17 in CRC were examined by cell proliferation, colony formation, adhesion, invasion and mouse xenograft assays. Methylation­specific PCR and bisulfite sequencing PCR were also carried out to investigate the promoter methylation status of KLF17 in CRC cells and tissues and explore the effects of lentiviral­mediated RNAi of UHRF1 on the methylation and expression of KLF17. The results revealed that KLF17 expression was abnormally decreased in CRC and associated with lymph node metastasis and unfavorable overall survival. Moreover, ectopic KLF17 expression suppressed CRC cell growth and invasion in vitro and in vivo. In addition, the downregulation of KLF17 was associated with the hypermethylation of the CpG nucleotides on the KLF17 promoter. The knockdown of the epigenetic regulator UHRF1 reduced the methylation level of the KLF17 promoter and inhibited CRC cell adhesion, invasion and epithelial­mesenchymal transition by upregulating KLF17. The present findings indicated that KLF17 may act as a tumour suppressor gene in CRC and a potential independent prognostic biomarker in CRC patients. UHRF1 can suppress KLF17 expression through the hypermethylation of its promoter in CRC. These results offer insights into the KLF17 expression regulation in CRC and suggest an inhibitory effect of KLF17 on tumourigenesis.

Analysis of fecal microbiota in patients with functional constipation undergoing treatment with synbiotics.

This study was performed to identify changes to microbial composition after treatment with synbiotics in patients with functional constipation and to define the key microbiota in the pathogenesis of functional constipation. Fecal samples from 53 patients diagnosed with chronic functional constipation according to the Rome III criteria were analyzed using 16S rRNA sequencing. After treatment with synbiotics for 1 month, fecal samples were collected from 36 patients; after a total of 3 months, fecal samples were collected from 15 patients. The outcomes were compared with the intestinal microbiota profiles of 53 healthy community volunteers. The microbiota in the constipation group differed from that in the treatment group and healthy group. After synbiotic treatment for 1 and 3 months, the abundance of Escherichia/Shigella decreased, whereas that of Prevotella_9 and Lactococcus increased. Comparison of the microbiota among the three groups showed that Prevotella_9 was the characteristic bacteria that decreased in the constipation group and increased in the treatment group. Synbiotic treatment can improve the microbiota in patients with constipation. Identification of the key bacterial genus is important to reveal the mechanism and provide a reliable theoretical basis of synbiotic treatment. It will also promote relevant research of microbiota treatment and individualized treatments.

Identification of molecular mechanisms of glutamine in pancreatic cancer.

The aim of the present study was to explore the critical genes and molecular mechanisms in pancreatic cancer (PC) cells with glutamine. By analyzing microarray data GSE17632 from the Gene Expression Omnibus database, the DEGs between PC cells treated with glutamine and without glutamine were evaluated. Additionally, function enrichment analyses and protein-protein interaction (PPI) network construction of DEGs were performed. Network module and literature mining analyses were performed to analyze the critical DEGs in PC cells. In total, 495 genes were selected as DEGs between control and glutamine cells in PC. These DEGs were mainly enriched in several Gene Ontology (GO) terms in biological process, cellular components and molecular function. Additionally, they were also enriched in certain pathways, including metabolic pathways and the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. MYC, heat shock 70kDa protein 5 (HSPA5), interleukin 8 (IL8), and chemokine (C-X-C motif) receptor 4 (CXCR4) were hub genes in the PPI network. Furthermore, two sub-network modules of PPI network and two co-occurrence networks were obtained. The DEGs of MYC, HSPA5, IL18 and CXCR4 may exert important roles in molecular mechanisms of PC cells with glutamine.

SP1 mediates the link between methylation of the tumour suppressor miR-149 and outcome in colorectal cancer.

Although recent studies indicate that DNA methylation contributes to the down-regulation of microRNAs (miRNAs) in colorectal cancer (CRC), this field remains largely unexplored. To identify methylation-silenced miRNAs and clarify their role in CRC, we performed a microarray analysis and screened for miRNAs that were induced in CRC cells by 5-aza-2'-deoxycytidine treatment or by the knockdown of DNA methyltransferases. The DNA methylation status of the candidate miRNA was analysed by bisulphite sequencing PCR and methylation-specific PCR. We found that miRNA-149 (miR-149) was epigenetically silenced in CRC and down-regulation of miR-149 was associated with hypermethylation of the neighbouring CpG island (CGI). Quantitative RT-PCR analysis demonstrated that the miR-149 level was markedly reduced in 51.6% of the CRC tissues compared with matched non-cancerous tissues. In addition, low expression of miR-149 was associated with a greater depth of invasion (p = 0.012), lower 5-year survival rate (p = 0.025), and was found to be an independent prognostic factor for overall survival (p = 0.016) in a multivariate analysis. Moreover, transfection of miR-149 inhibited cell growth and invasion of CRC cells in vitro. We also identified mRNA for Specificity Protein 1 (SP1, Sp1), a potential oncogenic protein, as a target of miR-149. Our data suggest that, as a methylation-sensitive miRNA, miR-149 may play an important role as a tumour suppressor in CRC, which has prognostic and therapeutic implications.

Effects of Lactobacillus plantarum on gut barrier function in experimental obstructive jaundice.

AIM: To investigate the mechanisms of Lactobacillus plantarum (L. plantarum) action on gut barrier in preoperative and postoperative experimental obstructive jaundice in rats. METHODS: Forty rats were randomly divided into groups of sham-operation, bile duct ligation (BDL), BDL + L. plantarum, BDL + internal biliary drainage (IBD), and BDL + IBD + L. plantarum. Ten days after L. plantarum administration, blood and ileal samples were collected from the rats for morphological examination, and intestinal barrier function, liver function, intestinal oxidative stress and protein kinase C (PKC) activity measurement. The distribution and expression of the PKC and tight junction (TJ) proteins, such as occludin, zonula occludens-1, claudin-1, claudin-4, junction adhesion molecule-A and F-actin, were examined by confocal laser scanning microscopy, immunohistochemistry, Western blotting, real-time fluorescent quantitative polymerase chain reaction assay. RESULTS: L. plantarum administration substantially restored gut barrier, decreased enterocyte apoptosis, improved intestinal oxidative stress, promoted the activity and expression of protein kinase (BDL vs BDL + L. plantarum, 0.295 ± 0.007 vs 0.349 ± 0.003, P < 0.05; BDL + IBD vs BDL + IBD + L. plantarum, 0.407 ± 0.046 vs 0.465 ± 0.135, P < 0.05), and particularly enhanced the expression and phosphorylation of TJ proteins in the experimental obstructive jaundice (BDL vs BDL + L. plantarum, 0.266 ± 0.118 vs 0.326 ± 0.009, P < 0.05). The protective effect of L. plantarum was more prominent after internal biliary drainage ( BDL + IBD vs BDL + IBD + L. plantarum, 0.415 ± 0.105 vs 0.494 ± 0.145, P < 0.05). CONCLUSION: L. plantarum can decrease intestinal epithelial cell apoptosis, reduce oxidative stress, and prevent TJ disruption in biliary obstruction by activating the PKC pathway.

Protective effects of Lactobacillus plantarum against epithelial barrier dysfunction of human colon cell line NCM460.

AIM: To investigate the effects of Lactobacillus plantarum (L. plantarum) in the intestinal permeability and expression of tight junction (TJ) using the normal human colon cell line NCM460. METHODS: Paracellular permeability of NCM460 monolayers was determined by transepithelial electrical resistance and dextran permeability. Expression of TJ proteins in NCM460 cell monolayers was detected by Western blotting and quantitative real-time polymerase chain reaction. RESULTS: L. plantarum played an important role in increasing transepithelial electrical resistance and decreasing the permeability to macromolecules of NCM460 monolayers against the disruption caused by enteropathogenic Escherichia coli (E. coli) or enteroinvasive E. coli. L. plantarum also prevented the decrease in the expression of TJ proteins and F-actin in NCM460 cells. CONCLUSION: L. plantarum can protect against dysfunction of NCM460 intestinal epithelial barrier caused by enteropathogenic E. coli or enteroinvasive E. coli, and thus can be a potential candidate of therapeutic agents for the treatment of intestinal diseases.

Lactobacillus plantarum consumption increases PepT1-mediated amino acid absorption by enhancing protein kinase C activity in spontaneously colitic mice.

Although probiotic consumption has generally been shown to have many beneficial effects for the prevention and treatment of inflammatory bowel disease, the effects of Lactobacillus plantarum (LP) on intestinal nutrient absorption, particularly oligopeptide transporter 1 (PepT1)-mediated absorption of dietary protein under inflammatory conditions, has not yet been characterized. In this study, we first investigated the effects of LP consumption on plasma amino acid concentrations and PepT1-mediated absorption of cephalexin in the small intestine of wild-type (WT) mice and interleukin-10 knockout (IL-10(-/-)) mice, a model of spontaneous colitis. We then analyzed expression and distribution of PepT1 and protein kinase C (PKC) activity in the jejunum of these mice. LP consumption (10(9) colony-forming units/0.5 mL) delivered by gavage once per day for 4 wk increased the total plasma amino acid concentration and the concentration of plasma cephalexin through enhancement of PepT1-mediated uptake in LP treated IL-10(-/-) mice compared with IL-10(-/-) mice. However, Western blotting and quantitative PCR analysis revealed no significant differences in PepT1 protein and mRNA expression between LP-treated and untreated mice. Additionally, immunofluorescence analysis showed that PepT1 did not appear to be mislocalized in IL-10(-/-) mice. Interestingly, IL-10(-/-) mice had significantly lower PKC activity and expression of phosphorylated PKC compared with WT mice, and these decreases could be prevented by LP treatment. These data suggest that consumption of LP enhances PepT1-mediated amino acid absorption, likely through alterations in PKC activity, as opposed to changes in expression or distribution of PepT1 in the small intestine of IL-10(-/-) mice.

Lactobacillus plantarum ameliorates colonic epithelial barrier dysfunction by modulating the apical junctional complex and PepT1 in IL-10 knockout mice.

Probiotics are efficacious in the treatment of inflammatory bowel disease. However, the precise mechanisms remain unknown. To determine whether probiotic Lactobacillus plantarum (LP) ameliorates colonic epithelial barrier dysfunction present in interleukin-10 knockout (IL-10⁻(/)⁻) mice, IL-10⁻(/)⁻ and wild-type mice received LP or the vehicle for 4 wk. Colitis was assessed by histological scores and clinical manifestation, and gut paracellular permeability was measured by Ussing chamber. Oligopeptide transporter 1 (PepT1)-mediated transepithelial transport was evaluated by measuring the plasma cephalexin concentration. The expression and distribution of apical junctional complex (AJC) proteins and PepT1 were determined by Western blotting and immunofluorescence and their mRNA by reverse transcriptase-PCR. Spontaneous colitis was observed in all IL-10⁻(/)⁻ mice in which paracellular permeability was increased, in conjunction with decreased expression and redistribution of zonula occludens-1, occludin, claudin-1, and ß-catenin. PepT1 expression was increased, accompanied with an enhanced cephalexin transport. Colonic epithelial barrier dysfunction was further confirmed by increased bacterial translocation and proinflammatory cytokine production. Treatment with LP decreased colonic paracellular permeability with restoration of expression and distribution of AJC proteins and partially prevented PepT1 expression and cephalexin transport in IL-10⁻(/)⁻ mice. Moreover, treatment with LP also prevented bacterial translocation and proinflammatory cytokine production in IL-10⁻(/)⁻ mice. Results from this study indicated that treatment with LP may ameliorate colonic epithelial barrier dysfunction in IL-10⁻(/)⁻ mice, by modulating the AJC- and PepT1-mediated transepithelial transport.

HnRNP K and PDI marked response to chemotherapy to human colorectal cancer cells.

UNLABELLED: 5-Fluorouracil has been the chemotherapy agent of first-choice for colorectal cancer for many years, but since there are no proven predictors of a patient's response to therapy, all patients receive similar treatment. Consequently, identification of biomarkers for therapeutic effect is crucial for the development of novel therapeutic strategies. Two human colorectal cancer cell lines of different metastatic potential (LoVo and SW480) were studied. IC50 of 5-FU for both cell lines were measured by 3-(4,5-dimethy-lthiazol-2-yl)-2,5-diphenyltetrazolium assay and validated by cell cycle analysis. Then the cell lines were treated with 5-FU at IC50 concentration and protein was extracted for 2-DE. Differential protein spots were examined by MALDI-TOF/TOF MS. The expression levels of the different proteins were further confirmed by Western blot and immunofluorescence analyses. Eleven proteins were identified. Expression of heterogeneous nuclear ribonucleoprotein K (hnRNP K) in LoVo cells was higher than in SW480 cells, while protein disulfide isomerase (PDI) displayed the opposite trend. After treatment with 5-FU, the expression of hnRNP K in LoVo decreased more significantly than in SW480, while PDI in SW480 increased more significantly than in LoVo cells. CONCLUSION: hnRNP K and PDI in the two cell lines have different expression characteristics. The sensitivity to 5-FU is not consistent in tumor progression. It may assist in development of novel treatment strategies for colorectal cancer metastasis.

Effects of oral Lactobacillus plantarum on hepatocyte tight junction structure and function in rats with obstructive jaundice.

Surgery and infection are prominent risk factors for the development of obstructive cholestasis which in turn is associated with failure of the liver barrier. We studied the effects of oral Lactobacillus plantarum (LP) supplementation on endotoxemia, oxidative stress, apoptosis, and tight junctions of hepatocytes in an experimental model of obstructive jaundice. Fifty male Wistar rats were randomly divided into five groups of 10 each: group I, sham-operated; group II, ligation and division of the common bile duct (BDL); group III, BLD followed by oral LP treatment; group IV, BDL followed by internal biliary drainage (IBD); group V, BDL followed by IBD and oral LP treatment. Hepatocyte apoptosis, plasma reduced glutathione (GSH) and oxidized glutathione (GSSG) levels, and portal blood endotoxin levels were measured and changes in tight junction-associated proteins occludin, claudin-1, claudin-4, and ZO-1 were observed. Compared to the sham-operated group I, significant increases in endotoxemia, apoptosis, and GSSG were observed in group II and significant decreases were observed in group V. Tight junctions were destroyed in group II animals but were not in animals treated with oral LP (groups III and V). An increase in occludin, claudin-1, claudin-4, and ZO-1 mRNA and protein levels were detected in livers in LP-treated animals (group V) compared with group II levels. Oral LP treatment of rats with obstructive jaundice assisted in the return of active hepatic barrier function. These results may lead to treatments to prevent the deleterious effects of obstructive jaundice.

[Proteomic research of biomarker of colorectal cancer metastasis].

OBJECTIVE: To explore the potential markers of colorectal cancer metastasis and the influence of 5-FU on differentially expressed proteins by using proteomic technology, and to elucidate the mechanism of colorectal cancer metastasis. METHODS: Human colorectal carcinoma cell lines of different metastatic potential, Lovo and SW480 were conventionally cultured, and the protein was extracted. 50% inhibitory concentration (IC(50)) of 5-FU to these two cell lines was measured by MTT assay. Proteins of these two cell lines after intervention by 5-FU at IC(50) were extracted, then 2-dimensional gel electrophoresis was conducted for the proteins. The differential protein spots were examined by mass spectrometry and analyzed by bioinformatics. Difference of expressed proteins in two cell lines before and after the intervention of 5-FU was validated by Western blot and immunofluorescence. RESULTS: Eleven differentially expressed proteins were identified by 2-dimensional gel electrophoresis and mass spectrometry. The hnRNP K protein and PDI were selected to be examined by Western blot and immunofluorescence. Results revealed that the expression of hnRNP K in Lovo was higher than that in SW480, while the expression of PDI was lower in Lovo. After intervention by 5-FU at IC(50), the expression of hnRNP K in Lovo decreased more as compared to SW480, while the expression of PDI in SW480 increased more as compared to Lovo. CONCLUSION: There are significant differences in expression of hnRNP K and PDI proteins between Lovo and SW480 cell lines, and the proteins alter regularly after 5-FU intervention.

Heterogeneous nuclear ribonucleoprotein A1 is identified as a potential biomarker for colorectal cancer based on differential proteomics technology.

Colorectal cancer (CRC) is the third most common cancer worldwide and has poor prognosis. To identify the proteins involved in colorectal carcinogenesis, we employed 2-DE and MALDI-TOF/TOF-based proteomics approach to study the differentially expressed proteins in tumor and adjacent nontumor tissue samples. Samples from 10 colorectal patients were analyzed. Of the 7 significantly and consistently altered proteins identified, hnRNP A1 was one of the most significantly altered proteins and its overexpression was confirmed using RT-PCR and Western blot analyses. Immunohistochemical examination showed that the enhanced expression of hnRNP A1 was correlated with the increasing severity of colorectal tissue and the progression of the colorectal cancer, as well as UICC (International Union against Cancer) staging, histo-differentiation, recurrence and decreased survival. By developing a highly sensitive immunoassay, hnRNP A1 could be detected in human serum and was significantly elevated in CRC patients compared with healthy volunteers. We proposed that hnRNP A1 could be considered as a novel serum tumor marker for CRC that may have significance in the detection and in the management of patients with this disease. Knockdown of hnRNP A1 expression by RNA interference led to the significant suppression of the cell growth in colorectal cancer SW480 cells in vitro. These data suggested that hnRNP A1 may be a potential biomarker for early diagnosis, prognosis, and monitoring in the therapy of colorectal cancer. Further studies are needed to fully assess the potential clinical value of this biomarker candidate.

Influences of enteral nutrition combined with probiotics on gut microflora and barrier function of rats with abdominal infection.

AIM: To investigate the influences of enteral, parenteral nutrition and probiotics delivered by gut on intestinal microecology, epithelial tight junctions, immune and barrier function of rats with abdominal infection. METHODS: Rat abdominal infection models established with cecal ligation and perforation method, were divided into three groups: parenteral nutrition (PN group, n = 7), PN+enteral nutrition (EN group, n = 7) and PN + EN + probiotics (probiotics group, n = 7) via the needle jejunostomy and neck vein for five days. The total nutritional supplement of the three groups was isonitrogenic and isocaloric. Probiotics was delivered by jejunostomy 10 mL/d (1 x 10(8) cfu/mL). The rats were killed on the sixth day. The feces in the cecum were cultured for anaerobic bacterial growth and analyzed with bacterial group DNA fingerprint profile with random amplified polymorphic DNA. The transmembrane binding proteins (occludin) and IgA level in plasma cells of intestine epithelium in colon and terminal ileum were measured by an immunohistochemistry method. The ultrastructure of intestinal epithelial tight junctions in colon and small intestine was observed by electron-microscopy. Vena cava blood and the homogenated tissue of liver, lung and mesenteric lymph nodes were cultured to determine the bacterial translocations, and endotoxin in the blood from portal vein was detected. RESULTS: (1) The amount of bacteria of gut species in EN group and probiotic group was higher than that in PN group. The DNA-profiles in EN group and probiotic group were similar to that of normal rats. The number of DNA-profiles in probiotics group was much more than that in PN group and EN group. Moreover, there were strange stripes in PN group. (2) The expression of occludin and IgA in the small and large intestine in EN group (2.309 +/- 0.336, 15.440 +/- 2.383) and probiotic group (2.938 +/- 0.515, 16.230 +/- 3.183) was improved as compared with PN group (1.207 +/- 0.587, P < 0.05, 11.189 +/- 2.108, P < 0.01). The expression of occludin in probiotic group (intestine: 2.93 +/- 0.515; cecum: 3.40 +/- 0.617) was higher than that in EN group (intestine: 2.309 +/- 0.336; cecum: 2.076 +/- 0.670; P < 0.05). The expression of IgA, especially in EN group (intestine: 15.440 +/- 2.383) and probiotic EN group (large intestine: 12.516 +/- 1.542) significantly increased as compared with PN group (intestine: 11.189 +/- 2.108; cecum: 10.160 +/- 1.643; P<0.01). The intestinal epithelial tight junctions and microvilli of the probiotic group were more intact than those in the PN group. (3) The bacterial translocations in blood, liver, lung and mesenteric lymph nodes, and the levels of endotoxin were significantly reduced in probiotic (0.082 +/- 0.029) and EN (0.125 +/- 0.040) groups as compared with PN group (0.403 +/- 0.181, P < 0.05). CONCLUSION: Application of EN combined with probiotics could improve the expression of transmembrane binding proteins (occludin) and IgA, correct the intestinal flora disturbance, maintain gut barrier functions and tight junctions, and reduce the occurrence of gut bacterial translocation.

[Influences of enteral nutrition combined with probiotics on the gut microecology and barrier function of the rats with abdominal infection].

OBJECTIVE: To investigate the influences of enteral nutrition (EN), parenteral nutrition (PN) and probiotics supplement on the intestinal microecology, and barrier function of the rats with abdominal infection. METHODS: Twenty-one Sprague-Dawley (SD) rats with abdominal infection were randomly divided into three groups, and received PN (PN group, n=7), PN+ EN (PN+ EN group, n=7) or PN+ EN+ probiotics (probiotics group, n=7) respectively with isonitrogen and isocaloric nutrition. The rats were sacrificed after six days. The feces in cecum were cultured for anaerobic bacterial growth and DNA fingerprint spectrum was analyzed by randomly amplified polymorphic DNA technique. The transmembrane binding protein (occludin) and IgA levels in colon and terminal ileum were detected by immunohistochemistry method. The bacterial translocation rate and endotoxin level were also measured. RESULTS: The germ numbers of different species were both higher in PN+ EN and probiotic group than those in PN group. The bands of DNA fingerprint spectrum were significantly decreased in PN group, but the bands in both PN+ EN group and probiotic group were similar to that in the normal rats. The expression levels of occludin and IgA in the intestine and colorectum were higher in both PN+ EN group and probiotic group compared with those of PN group (P< 0.05, P< 0.01, respectively), the expression level of occludin was higher in probiotic group than that in PN+ EN group (P< 0.05). The overall bacterial translocation rates and endotoxin levels were significantly reduced in both probiotic and PN+ EN group (P< 0.05), but there was no difference between probiotic group and EN group. CONCLUSION: EN combined with probiotics can increase occluding and IgA expressions, improve the intestinal microecology,maintain the gut barrier function, and decrease the incidence of gut bacterial translocation.

Effect of lactobacillus on the gut microflora and barrier function of the rats with abdominal infection.

AIM: To investigate the effect of probiotics supplemented by gut on the tight junctions of epithelial cells, barrier function and the microflora of rats with abdominal infection. METHODS: After the model of cecal ligation and perforation established, SD rats were divided into two groups: parenteral nutrition (PN) group and PN+probiotics (probiotics) group, PN solution was supplemented by neck vein and probiotics was delivered via the jejunostomy tube for five days. Vena cava blood and the homogenated tissue of liver, lung and mesenteric lymph nodes were cultured to determine the bacterial translocation rate (BTR). The ultra-structure of epithelial tight junctions and microvilli of the gut were observed by electron microscopy; occluding expression was measured by indirect-immune fluorescence method; anaerobic bacterial growth by anaerobic culture and DNA fingerprint of bacterial colonies of the feces by PCR. RESULTS: The quantity of lactobacteria and bifydobacteria in probiotics group was higher than that of PN group. The profiles of DNA fingerprint expression in probiotics group were similar to that in the normal group, a new 16S rDNA sequence appeared in the profile in PN group. The occludin expression, the integrality of the gut epithelial tight junction and microvilli in probiotics group were improved as compared with PN group. The BTR and endotoxin in blood were reduced more significantly in probiotics group as compared with PN group. CONCLUSION: The probiotics could improve the gut microflora disturbance, increase occludin expression, maintain the gut epithelial tight junction and decrease the bacterial translocations rate.