Cytokines, NF-kappaB, microenvironment, intestinal inflammation and cancer

Identification of gene expression changes from colitis to CRC in the mouse CAC model

A connection between colorectal carcinogenesis and inflammation is well known, but the underlying molecular mechanisms have not been elucidated. Chemically induced colitis-associated cancer (CAC) is an outstanding mouse model for studying the link between inflammation and cancer. Additionally, the CAC model is used for examining novel diagnostic, prognostic, and predictive markers for use in clinical practice. Here, a CAC model was established in less than 100 days using azoxymethane (AOM) with dextran sulfate sodium salt (DSS) in BALB/c mice. We examined the mRNA expression profiles of three groups: control untreated mice (K), DSS-induced chronic colitis mice (D), and AOM/DSS-induced CAC (AD) mice. We identified 6301 differentially expressed genes (DEGs) among the three groups, including 93 persistently upregulated genes and 139 persistently downregulated genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses revealed that the most persistent DEGs were significantly enriched in metabolic or inflammatory components in the tumor microenvironment. Furthermore, several associated DEGs were identified as potential DEGs by protein-protein interaction (PPI) network analysis. We selected 14 key genes from the DEGs and potential DEGs for further quantitative real-time PCR (qPCR) verification. Six persistently upregulated, 3 persistently downregulated DEGs, and the other 3 genes showed results consistent with the microarray data. We demonstrated the regulation of 12 key genes specifically involved in Wnt signaling, cytokine and cytokine receptor interactions, homeostasis, and tumor-associated metabolism during colitis-associated CRC. Our results suggest that a close relationship between metabolic and inflammatory mediators of the tumor microenvironment is present in CAC.

MicroRNA-155 is involved in the pathogenesis of ulcerative colitis by targeting FOXO3a

BACKGROUND

MicroRNAs (miRNAs) are important posttranscriptional regulators of gene expression. The precise role of miRNAs in ulcerative colitis (UC) is not completely understood. The purpose of this study was to identify miRNAs that are induced in patients with active UC and to assess the effect of miR-155 on improving intestinal inflammation.

METHODS

The miRNA profiles in patients with active UC (n = 20) and healthy subjects (n = 16) were examined using miRNA microarrays. miR-155 upregulation was confirmed by quantitative RT-PCR. Regulation of the target gene FOXO3a expression by miR-155 was assessed using luciferase reporter construct assays and miR-155 mimic or inhibitor transfections. The effects of FOXO3a or miR-155 on IκBα or IL-8 were detected by Western blot or enzyme-linked immunosorbent assay in HT29 cells, respectively.

RESULTS

We identified 68 miRNAs that were differentially expressed (33 upregulated and 35 downregulated) in patients with active UC compared with healthy controls. One of the upregulated miRNAs in the UC tissue was miR-155 (1.22-fold, P < 0.03), which plays a key role in the regulation of inflammatory pathways. In patients with active UC, miR-155 was significantly upregulated, and the expression of FOXO3a dramatically decreased. Luciferase reporter assays demonstrated that miR-155 directly targets FOXO3a and affects the protein expression of FOXO3a in HT29 cells. Moreover, silenced FOXO3a and the overexpression of miR-155 increased the levels of IL-8 in TNF-α-treated HT29 cells by suppressing the inhibitory IκBα.

CONCLUSIONS

miR-155 appears to play a role in the intestinal inflammation of patients with active UC by downregulating the expression of FOXO3a. This process may activate the nuclear factor kappa B signaling pathway.

Regulated expression of PTPRJ/CD148 and an antisense long noncoding RNA in macrophages by proinflammatory stimuli

PTPRJ/CD148 is a tyrosine phosphatase that has tumour suppressor-like activity. Quantitative PCR of various cells and tissues revealed that it is preferentially expressed in macrophage-enriched tissues. Within lymphoid tissues immunohistochemistry revealed that PTPRJ/CD148 co-localised with F4/80, indicating that macrophages most strongly express the protein. Macrophages express the highest basal level of ptprj, and this is elevated further by treatment with LPS and other Toll-like receptor ligands. In contrast, CSF-1 treatment reduced basal and stimulated Ptprj expression in human and mouse cells, and interferon also repressed Ptprj expression. We identified a 1006 nucleotide long noncoding RNA species, Ptprj-as1 that is transcribed antisense to Ptprj. Ptprj-as1 was highly expressed in macrophage-enriched tissue and was transiently induced by Toll-like receptor ligands with a similar time course to Ptprj. Finally, putative transcription factor binding sites in the promoter region of Ptprj were identified.

Overview of molecular pathways in inflammatory bowel disease associated with colorectal cancer development

Patients with long-standing inflammatory bowel disease (IBD) are at a higher risk of developing colorectal cancer (CRC). This risk increases with the longer duration of colitis, greater extent of inflammation, a family history of CRC, severity of bowel inflammation, and a coexistent primary sclerosing cholangitis. The cornerstone for comprehending the development of CRC in IBD and hence early detection is based on the understanding of the molecular pathways of IBD itself. At a molecular level, the pathogenesis of CRC is related to understanding the inflammatory changes and involves multiple inter-related pathways including (i) genetic alterations (e.g. chromosomal and microsatellite instability and hypermethylation), (ii) mucosal inflammatory mediators (e.g. COX-2, interleukin-6, interleukin-23, tumor necrosis factor-α, nuclear factor-κB, and chemokines), (iii) changes in the expression of receptors on the epithelial cells, and (iv) oxidant stress, mucosal breakdown, and intestinal microbiota. The aim of this review is to provide an evidence-based approach for the role of chronic inflammatory mechanisms and the molecular basis of these mechanisms in the development of CRC. Therefore, understanding the molecular basis of CRC is an important step for the identification of new biomarkers that can help in the early detection of CRC in these patients.

The role of chemoprevention of colorectal cancer with 5-aminosalicylates in ulcerative colitis

5-aminosalicylates (5-ASA) are widely used to treat patients with ulcerative colitis. Experimental data suggest that these agents can potentially be used in a chemopreventive fashion to inhibit the development of colitis-associated colorectal cancer (CRC); however, observational studies investigating a possible risk reduction of CRC by 5-ASA therapy have revealed conflicting results. Currently, it appears that 5-ASA have no or only a very limited effect as a deterrence against CRC. Thus, a general recommendation for long-term use of 5-ASA solely for chemopreventive measures is not warranted.

Oroxylin A prevents inflammation-related tumor through down-regulation of inflammatory gene expression by inhibiting NF-κB signaling

Increasing evidence suggests that inflammatory microenvironment plays a critical role at different stages of tumor development. However, the molecular mechanisms of the interaction between inflammation and proliferation of cancer cells remain poorly defined. Here we reported the inhibitory effects of oroxylin A on the inflammation-stimulated proliferation of tumor cells and delineated the mechanism of its action. The results indicated that treatment with oroxylin A inhibited NF-κB p65 nuclear translocation and phosphorylation of IκBα and IKKα/β in both human colon tumor HCT116 cells and human monocytes THP-1 cells. In addition, in THP-1 cells, oroxylin A significantly suppressed lipopolysaccharide (LPS)-induced secretion of prototypical proinflammatory cytokine IL-6 but not IL-1β, and it was confirmed at the transcription level. Moreover, oroxylin A inhibited the proliferation of HCT116 cells stimulated by LPS-induced THP-1 cells in co-culture microenvironment. In summary, oroxylin A modulated NF-κB signaling pathway involved in inflammation-induced cancer initiation and progression and therefore could be a potential cancer chemoprevention agent for inflammation-related cancer.

IL-6-induced DNMT1 activity mediates SOCS3 promoter hypermethylation in ulcerative colitis-related colorectal cancer

Ulcerative colitis (UC) is associated with a high risk of developing colorectal cancer (CRC). The mechanisms by which chronic inflammatory responses in the colon may promote CRC remain only partially understood, but may involve reduced negative regulation of interleukin (IL)-6 signaling towards signal transducer and activator of transcription 3 activation through the loss of SOCS3 expression, unleashing the full carcinogenic potential of this transcription factor. Thus, we analyzed SOCS3 expression in the colon of healthy controls, as well as in a cohort of UC patients with varying degrees of dysplasia. We observe that the loss of epithelial SOCS3 expression delimits the areas subject to dysplasia in UC, suggesting an important tumour-suppressive role of SOCS3 downregulation, early in the transformation process. Importantly, methylation of the SOCS3 promotor appears to constitute an important regulatory mechanism for colonic SOCS3 expression as SOCS3 methylation status in CRC cells correlates with a disability to upregulate SOCS3 upon IL-6 stimulation, whereas forced demethylation using 5-aza-2'-deoxycytidine restores SOCS3 expression and inhibits IL-6-induced p-signal transducer and activator of transcription 3 activation and proliferation. Expression of the DNA methyltransferase gene DMNT1 is prominent in dysplastic cells and correlates with low or absent SOCS3 expression. Thus, induction of DNMT1 expression in the chronically inflamed colon may release IL-6 signaling towards signal transducer and activator of transcription 3 from inhibition through SOCS3 increasing the propensity to malignant transformation. Hence, DNMT1 emerges as a rational target in preventive strategies aimed at counteracting UC-CRC.

Immune microenvironmental shift along human colorectal adenoma-carcinoma sequence: is it relevant to tumor development, biomarkers and biotherapeutic targets?

Human colorectal carcinoma (CRC) is one of the leading cancers. Every year, the WHO estimates a total of 945,000 new CRC cases, with 492,000 deaths worldwide. Most CRCs arise from the main premalignant lesion, colorectal adenomas, and the progression of colorectal adenoma to CRCs may take a long-term time course. The development of human CRCs is not only determined by the adenomatous cells, but also by the interaction between adenomatous cells and host immune environment. In response to tumor initiation or invasion, many inflammatory cells and components will be inevitably activated and form an inflammatory microenvironment surrounding the CRC tumors. Accumulative evidence has revealed that inflammatory response plays a key role in the development of human CRCs by implicating in many aspects including in determining the microenvironmental immune function shift from immunosurveillance to immunosuppression and significantly influences the progression of precancerous lesions to cancers. In this review, the functional changes of immune microenvironment from precancerous stage (adenoma) to cancer stage are summarized, and their potential as predictive biomarkers and biotherapeutic significance in preventing the development of CRCs are discussed.

Association of the OCTN1/1672T variant with increased risk for colorectal cancer in young individuals and ulcerative colitis patients

BACKGROUND

Ulcerative colitis (UC) is associated with colorectal cancer. Chronic inflammation may also play a role in the pathogenesis of sporadic colorectal cancer (SCC), particularly in younger patients (<55 years). We evaluated whether single nucleotide polymorphisms of the OCTN1 and OCTN2 genes are associated with UC, SCC, and with UC cases with cancer progression (UCCP).

METHODS

We evaluated the OCTN1 and OCTN2 polymorphisms in 200 patients with UC, 59 patients with UCCP, 200 patients with SCC, and 200 controls (HC). IL-8 expression was also assessed by real-time polymerase chain reaction (PCR). Additionally, we transfected human colon carcinoma Caco2 cells, homozygous for OCTN1/1672T variant, with the OCTN1/1672C allele and NF-κB activity was evaluated by luciferase based reporter assay and IL-8 mRNA expression by real-time PCR.

RESULTS

OCTN2 polymorphisms did not present a significant association with any group of patients compared to normal controls. Conversely, homozygosity for the OCTN1/1672T variant was significantly associated with UC (P = 0.047 vs. HC), with UCCP (UCCP vs. HC, P < 0.001), and with SCC developing in early age (<55 years) (P = 0.021 vs. HC). Importantly, IL-8 mRNA expression was higher in UC and UCCP patients homozygous for the OCTN1 1672T variant compared to the other genotypes. Moreover, in Caco2 cells transfection of the OCTN1/1672C variant reduced the activity of the proinflammatory factor NF-κB.

CONCLUSION

Our data demonstrate that OCTN1 could have a role in modulating the severity of chronic inflammation associated with SCC in early age and in UC patients, and that its polymorphisms may help to predict malignant progression of IBD.

The role of gut microbiota (commensal bacteria) and the mucosal barrier in the pathogenesis of inflammatory and autoimmune diseases and cancer: contribution of germ-free and gnotobiotic animal models of human diseases

Metagenomic approaches are currently being used to decipher the genome of the microbiota (microbiome), and, in parallel, functional studies are being performed to analyze the effects of the microbiota on the host. Gnotobiological methods are an indispensable tool for studying the consequences of bacterial colonization. Animals used as models of human diseases can be maintained in sterile conditions (isolators used for germ-free rearing) and specifically colonized with defined microbes (including non-cultivable commensal bacteria). The effects of the germ-free state or the effects of colonization on disease initiation and maintenance can be observed in these models. Using this approach we demonstrated direct involvement of components of the microbiota in chronic intestinal inflammation and development of colonic neoplasia (i.e., using models of human inflammatory bowel disease and colorectal carcinoma). In contrast, a protective effect of microbiota colonization was demonstrated for the development of autoimmune diabetes in non-obese diabetic (NOD) mice. Interestingly, the development of atherosclerosis in germ-free apolipoprotein E (ApoE)-deficient mice fed by a standard low-cholesterol diet is accelerated compared with conventionally reared animals. Mucosal induction of tolerance to allergen Bet v1 was not influenced by the presence or absence of microbiota. Identification of components of the microbiota and elucidation of the molecular mechanisms of their action in inducing pathological changes or exerting beneficial, disease-protective activities could aid in our ability to influence the composition of the microbiota and to find bacterial strains and components (e.g., probiotics and prebiotics) whose administration may aid in disease prevention and treatment.

High-fat diet increases NF-κB signaling in the prostate of reporter mice

BACKGROUND

High-fat diet (HFD) is considered as a major risk factor for benign prostatic diseases and cancer in the Western world. Studies have shown an association between oxidative stress and prostatic diseases. NF-κB has been implicated in stress response and is deregulated in prostrate disorders; therefore, we sought to determine whether HFD could induce oxidative stress in the prostate which could contribute to prostatic diseases.

METHODS

Transgenic NF-κB-Luc-Tag mice were either fed with regular diet (RD) or HFD for 12 weeks. Serial, non-invasive molecular imaging was performed to study NF-κB activation in the whole body, and in various organs including thymus, spleen, and prostate. Western blotting was used to determine the expression of NF-κB, its upstream and downstream targets in the prostate.

RESULTS

Twofold increase in whole body NF-κB activity in vivo and two to threefold upregulated prostate NF-κB activity ex vivo were observed after HFD intake compared with RD controls. HFD-induced NF-κB activity was elevated remarkably in the abdominal cavity, thymus, spleen, and prostate with increase in prostrate weight. In the prostrate, an increase in the protein expression of gp91(phox) , p22(phox) , and p47(phox) NADPH oxidase subunits was observed suggesting the involvement of HFD in causing oxidative stress. Nuclear extracts from the prostrate tissue showed an increased expression of p65/RelA that corresponded with elevated cytosolic levels of p-IκBα, along with increased expression of downstream targets of NF-κB, nitric oxide synthase, and cyclooxygenase-2.

CONCLUSIONS

Our findings suggest that HFD-mediated oxidative stress and deregulation of NADPH oxidase leads to NF-κB activation in the prostrate.

Correlation of NF-kappaB signal pathway with tumor metastasis of human head and neck squamous cell carcinoma

Background

Nuclear factor-kappa B (NF-κB) signaling constitutes a key event in the multistep process of carcinogenesis, progression and treatment in many cancer types. However, the significance of NF-κB pathway for complex and tissue-specific aspects of head and neck cancer progression, such as invasion and metastasis, is less understood.

Methods

The expression of NF-κB p65 in squamous cell carcinoma of the head and neck (SCCHN) clinical specimens by immunohistochemistry. The role of NF-κB activity in head and neck squamous cell carcinoma was determined by western blot, reporter assay and EMSA analysis in vitro and metastasis assays in vivo in different metastatic potential tumor cells. Furthermore, the apoptosis rate and expression of metastasis-related protein such as MMP9 and VEGF were examined by Annexin V/PI staining and Western blot, respectively.

Results

A higher level of active nuclear-localized NF-κB was observed in the metastatic SCCHN specimens group (p < 0.01). The NF-κB activities of SCCHN cell lines with different metastatic potentials were then determined and in excellent agreement with results found in SCCHN specimens, highly metastatic SCCHN cell lines expressed high level of NF-κB activity. The treatment of highly metastatic SCCHN cells with NF-κB inhibitors reduced the in vitro cell invasion capacity of the cells without affecting the apoptotic rate. Additionally, the NF-κB inhibitors significantly inhibited the experimental lung metastasis of Tb cells and lymph node metastasis of TL cells in nude mice. Furthermore, the expression of metastasis-related proteins, such as matrix metalloproteinase 9 and vascular endothelial growth factor, was inhibited by pyrrolidine dithiocarbonate.

Conclusions

This study suggests that NF-κB activity significantly contributes to tumor hematologic and lymphatic metastases and may aid in the development of early detection methods or therapies targeting non-conventional molecular targets.

In vivo chemoresistance of prostate cancer in metronomic cyclophosphamide therapy

A human prostate cancer (PC3) xenograft model was established which reflects acquired in vivo resistance towards metronomic cyclophosphamide (CPA) treatment. Cell cultures of two in vivo resistant PC3 tumors were established which maintain chemoresistant phenotypes upon xenografting into mice. A comparative proteome analysis of the two resistant cell lines PC3-D3 and -D4 versus the non-resistant parental PC3 cell line by 2D-DIGE approach followed by MALDI-TOF-TOF analysis revealed a total of 25 differently expressed proteins. Validation of protein candidates by Western blot analysis of the corresponding in vivo tumor xenografts identified three differentially expressed proteins (thioredoxin containing protein 5, cathepsin B, and annexin A3). Thioredoxin containing protein 5 was up-regulated in resistant xenografts only upon in vivo CPA therapy. A truncated version of cathepsin B translocated into mitochondria in the resistant clones whereas it stays cytoplasmic in corresponding parental PC3 cells. Annexin A3 (ANXA3) presents a very interesting candidate which was found to be up-regulated both in vitro and in xenografts, with protein levels further increased by metronomic CPA treatment in vivo. It is noteworthy that independent studies in other epithelial cancers recently identified ANXA3 as cancer progression and resistance marker.

Formulation and in vitro characterization of spray-dried antisense oligonucleotide to NF-kappaB encapsulated albumin microspheres

The aim of this study was to formulate and characterize microspheres containing antisense oligonucleotide to NF-kappaB using bovine serum albumin as the polymer matrix. Microspheres were prepared by spray-drying technique with 5, 10 and 15% drug loading. Glutaraldehyde was used as a cross-linking agent. The particle sizes ranged from 3-5 microm. Microspheres were smooth and spherical in shape, as determined by scanning electron microscopy (SEM). The yield of microspheres ranged from 70-75% and the encapsulation efficiencies were found to be in the range of 59-60%, as determined by a novel HPLC method. Zeta potential of the microspheres ranged between -39 to -53 mV, thus indicating good suspension stability in water. In-vitro release studies performed using phosphate buffer saline demonstrated extended drug release up to 72 h. Kinetic model fitting showed high correlation with the Higuchi model, suggesting that the drug release was primarily diffusion controlled.

Epithelial NF-kappaB enhances transmucosal fluid movement by altering tight junction protein composition after T cell activation

In inflammatory bowel disease (IBD), aberrant activation of innate and adaptive immune responses enhances mucosal permeability through mechanisms not completely understood. To examine the role of epithelial nuclear factor (NF-kappaB) in IBD-induced enhanced permeability, epithelial-specific IkappaBalpha mutant (NF-kappaB super repressor) transgenic (TG) mice were generated. NF-kB activation was inhibited in TG mice, relative to wild-type mice, following T cell-mediated immune cell activation using an anti-CD3 monoclonal antibody. Furthermore, epithelial NF-kappaB super repressor protein inhibited diarrhea and blocked changes in transepithelial resistance and transmucosal flux of alexa350 (0.35 kDa) and dextran3000 (3 kDa). In vivo perfusion loop studies in TG mice revealed reversed net water secretion and reduced lumenal flux of different molecular probes (bovine serum albumin, alexa350, and dextran3000). Cell-imaging and immunoblotting of low-density, detergent-insoluble membrane fractions confirmed that tight junction proteins (occludin, claudin-1 and zona occludens-1) are internalized through an NF-kappaB-dependent pathway. Taken together, these data suggest that IBD-associated diarrhea results from NF-kappaB-mediated tight junction protein internalization and increased paracellular permeability. Thus, reduction of epithelial NF-kappaB activation in IBD may repair defects in epithelial barrier function, reduce diarrhea, and limit protein (eg, serum albumin) losses. Epithelial NF-kappaB activation induced by mucosal T cells, therefore, actively plays a role in opening paracellular spaces to promote transmucosal fluid effux into the intestinal lumen.

Profiling of molecular pathways regulated by microRNA 601

MicroRNAs (miRNAs) have been implicated in complex vertebrate developmental and pathological systems as a versatile class of molecules involved in the regulation of various biological processes and molecular pathways. To elucidate the role of miRNAs in human somatic cells, an understanding of the molecular framework regulated by individual miRNA is essential. In this study, we examined the effect of hsa-miR-601 on gene expression changes in human lung cancer cells A549. To achieve this, DNA microarray and global pathway analyses were performed on hsa-miR-601 introduced cells for two successive days. Gene ontology analysis revealed that the effect of hsa-miR-601 over-represented the negative regulation of translation/translational initiation, whereas GenMAPP analysis revealed that several characteristic pathways were changed in hsa-miR-601 introduced A549 cells compared to control short RNA introduced cells. Among them, up-regulation of actin cytoskeleton and down-regulation of Fas-induced apoptosis pathway occurred on two successive days after hsa-miR-601 introduction. Using a luciferase reporter assay, we also showed that hsa-miR-601 specifically repressed nuclear factor-kappaB (NF-kappaB) transcription factor-dependent reporter expression, a key component of the immune-oncogenesis pathway. These findings suggest that hsa-miR-601 could affect a variety of signaling pathways accompanying orchestrated gene expression changes. Our results argue that individual miRNAs affect complex regulation of cellular signaling pathways.

Tumor suppressor FOXO3 participates in the regulation of intestinal inflammation

Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is characterized by chronic mucosal injury and the infiltration of inflammatory cells. Tumor suppressor FOXO3 regulates gene expression and its translocation to the cytosol leads to the abrogation of its transcriptional function. We have previously shown that bacterial infection regulates FOXO3 in intestinal epithelial cells and increases cytokine levels. As TNFalpha is a major contributor in intestinal inflammation, the aim of this study was to assess its effect on FOXO3 and FOXO3's contribution to intestinal inflammation in vitro and in vivo. TNFalpha induces the translocation of nuclear FOXO3 into the cytosol where it undergoes proteasomal degradation in human intestinal HT-29 cells. Proximally, the PI3K and IKK pathways mediate TNFalpha-induced FOXO3 phosphorylation. In FOXO3-silenced HT-29 cells, TNFalpha-induced IL-8 expression is increased approximately 83%. In vivo, Foxo3 is present in the nuclei and cytosol of colonic crypt epithelia. In DSS-induced colonic inflammation, Foxo3's nuclear localization is lost and it is only found in the cytosol. Consistent with a role for Foxo3 in colitis, Foxo3-deficient mice treated with DSS developed more severe colonic inflammation with an increased number of intraepithelial lymphocytes and PMNs infiltrated in the epithelia, than wild-type mice. In summary, TNFalpha inactivates FOXO3 in intestinal epithelia through the PI3K and IKK pathways and FOXO3 inactivation leads to the upregulation of IL-8 in vitro; in vivo Foxo3 is in the cytosol of inflamed colonic epithelia and Foxo3 deficiency leads to severe intestinal inflammation.

Up-regulated microRNA-143 transcribed by nuclear factor kappa B enhances hepatocarcinoma metastasis by repressing fibronectin expression

It is increasingly clear that hepatocellular carcinoma (HCC) has a distinct microRNA (miRNA) expression profile that is involved in malignancy; however, little is known about how functional miRNA modulates the metastasis of hepatitis B virus (HBV)-related HCC (HBV-HCC). In the present study, we demonstrate that the levels of miRNA-143 (miR-143) are dramatically increased in metastatic HBV-HCC of both p21-HBx transgenic mice and HCC patients. Moreover, we show that overexpression of this miRNA is transcribed by nuclear factor kappa B (NF-kappaB) and favors liver tumor cell invasive and metastatic behavior. Intratumoral administration of miR-143 shows that high levels of miR-143 can significantly promote HCC metastasis in an athymic nude mouse model. An in vivo study that used p21-HBx transgenic mice also showed that local liver metastasis and distant lung metastasis are significantly inhibited by blocking miR-143. Additionally, fibronectin type III domain containing 3B (FNDC3B), which regulates cell motility, was identified as the direct and functional target of miR-143 both in vivo and in vitro.

CONCLUSION

Up-regulation of miR-143 expression transcribed by NF-kappaB in HBV-HCC promotes cancer cell invasion/migration and tumor metastasis by repression of FNDC3B expression. The present study provides a better understanding of the specificity of the biological behavior and thus may be helpful in developing an effective treatment against HBV-HCC.

3,3'-diindolylmethane attenuates colonic inflammation and tumorigenesis in mice

BACKGROUND

3,3-Diindolylmethane (DIM) is a major in vivo product of acid-catalyzed oligomerization of indole-3-carbinol (I3C) derived from Brassica food plants. Although DIM is known as a chemopreventive and chemotherapeutic phytochemical, the effects of DIM on inflammation in vivo are still unknown. In the present study we investigated the antiinflammatory effects of DIM on experimental colitis and colitis-associated colorectal carcinogenesis.

METHODS

To determine if DIM has an antiinflammatory effect in vivo, we examined the therapeutic effects of DIM in dextran sodium sulfate (DSS)-induced experimental colitis and colitis-associated colon carcinogenesis induced by azoxymethane (AOM)/DSS in BALB/c mice.

RESULTS

Treatment with DIM significantly attenuated loss of body weight, shortening of the colon, and severe clinical signs in a colitis model. This was associated with a remarkable amelioration of the disruption of the colonic architecture and a significant reduction in colonic myeloperoxidase activity and production of prostaglandin E(2), nitric oxide, and proinflammatory cytokines. Further, DIM administration dramatically decreased the number of colon tumors in AOM/DSS mice.

CONCLUSIONS

These results suggest that DIM-mediated antiinflammatory action at colorectal sites may be therapeutic in the setting of inflammatory bowel disease and colitis-associated colon cancer.

Expression of chemokines and chemokine receptors in human colon cancer

Human colorectal cancer (CRC), the second largest cause of tumor-related death in Western countries, represents a paradigm for the now well-established connections between inflammation and cancer. In this study, we investigated which inflammatory mediators are mostly expressed in the microenvironment of human CRC. The RNA profile of a large panel of inflammatory genes, in particular chemokines and chemokine receptors, was analyzed in eight surgical tumor samples and in paired normal tissues from CRC patients. We employed an "inflammatory gene card" (TaqMan Low Density Array by Applied Biosystem), designed by our group, containing probes for 24 chemokines and 17 chemokine receptors. Several chemokines were strongly upregulated in the tumor microenvironment, most frequently CCL4 and CCL5, chemotactic for monocytes/macrophages and T cells, and the corresponding receptors CCR1 and CCR5; the angiogenic chemokines CXCL1 and CXCL8, and the receptor CXCR2. The antiangiogenic chemokines CXCL9 and CXCL10 were also expressed, but in the absence of the receptor CXCR3. Selected results have been confirmed in a larger number of samples. The levels of mRNA CXCL8 were significantly associated with the levels of osteopontin, a matrix-associated protein that shares with chemokines important functions such as induction of cell migration and survival, and modulation of the neoangiogenesis. Overall these results could be helpful to identify the most relevant inflammatory pathways present in CRC tumors and to build a solid rationale for future therapeutic interventions based on anti-inflammatory strategies.

Modulation of the fecal microflora profile and immune function by a novel trans-galactooligosaccharide mixture (B-GOS) in healthy elderly volunteers

BACKGROUND

Aging is associated with reduced numbers of beneficial colonic bifidobacteria and impaired immunity. Galactooligosaccharides (GOSs) stimulate the growth of bifidobacteria in younger adults, but little is known about their effects in the elderly and their immunomodulatory capacity.

OBJECTIVE

We assessed the effect of a prebiotic GOS mixture (B-GOS) on immune function and fecal microflora composition in healthy elderly subjects.

DESIGN

In a double-blind, placebo-controlled, crossover study, 44 elderly subjects were randomly assigned to receive either a placebo or the B-GOS treatment (5.5 g/d). Subjects consumed the treatments for 10 wk, and then went through a 4-wk washout period, before switching to the other treatment for the final 10 wk. Blood and fecal samples were collected at the beginning, middle (5 wk), and end of the test period. Predominant bacterial groups were quantified, and phagocytosis, natural killer (NK) cell activity, cytokine production, plasma cholesterol, and HDL cholesterol were measured.

RESULTS

B-GOS significantly increased the numbers of beneficial bacteria, especially bifidobacteria, at the expense of less beneficial groups compared with the baseline and placebo. Significant increases in phagocytosis, NK cell activity, and the production of antiinflammatory cytokine interleukin-10 (IL-10) and significant reduction in the production of proinflammatory cytokines (IL-6, IL-1beta, and tumor necrosis factor-alpha) were also observed. B-GOS exerted no effects on total cholesterol or HDL-cholesterol production, however.

CONCLUSIONS

B-GOS administration to healthy elderly persons resulted in positive effects on both the microflora composition and the immune response. Therefore, B-GOS may be a useful dietary candidate for the enhancement of gastrointestinal health and immune function in elderly persons.

Inhibition of oncogene-induced inflammatory chemokines using a farnesyltransferase inhibitor

Background

Farnesyltransferase inhibitors (FTI) are small molecule agents originally formulated to inhibit the oncogenic functions of Ras. Although subsequent analysis of FTI activity revealed wider effects on other pathways, the drug has been demonstrated to reduce Ras signaling by direct measurements. The purpose of the current study was to determine if FTI could be used to inhibit the inflammatory activities of a known Ras-activating human oncoprotein, RET/PTC3. RET/PTC3 is a fusion oncoprotein expressed in the thyroid epithelium of patients afflicted with thyroid autoimmune disease and/or differentiated thyroid carcinoma. Previous studies have demonstrated that RET/PTC3 signals through Ras and can provoke nuclear translocation of NFκB and the downstream release of pro-inflammatory mediators from thyroid follicular cells in vitro and in vivo, making it an ideal target for studies using FTI.

Methods

For the studies described here, an in vitro assay was developed to measure FTI inhibition of RET/PTC3 pro-inflammatory effects. Rat thyrocytes transfected with RET/PTC3 or vector control cDNA were co-cultured with FTI and examined for inhibition of chemokine expression and secretion measured by RT-PCR and ELISA. Immunoblot analysis was used to confirm the level at which FTI acts on RET/PTC3-expressing cells, and Annexin V/PI staining of cells was used to assess cell death in RET/PTC3-expressing cells co-cultured with FTI.

Results

These analyses revealed significant mRNA and protein inhibition of chemokines Ccl2 and Cxcl1 with nanomolar doses of FTI. Neither RET/PTC3 protein expression nor apoptosis were affected at any dose of FTI investigated.

Conclusion

These data suggest that FTI may be applied as an effective inhibitor for RET/PTC3-oncogene induced pro-inflammatory mediators.

Convergence of genetic, nutritional and inflammatory factors in gastrointestinal cancers

Gastrointestinal cancers account for 20% of all cancer incidences worldwide. Colorectal cancer is the second most common cause of all cancer-related mortality and is increasing in Western societies. Infection and inflammation contribute to 15-20% of all malignancies, and are predisposing risk factors for gastrointestinal cancers. Helicobacter pylori infection is commonly associated with gastric cancers, and chronic inflammation increases the risk of colorectal cancer by 1% per year. Micronutrient status and common genetic variations in human populations modify risk for gastrointestinal cancer. Chronic inflammation promotes carcinogenesis by inducing gene mutations, inhibiting apoptosis, and stimulating angiogenesis and cell proliferation. Inflammation also induces epigenetic alterations that are associated with cancer development. Two key genes in the inflammatory process, cyclooxygenase-2 (COX-2) and nuclear factor-kappa B (NF-kappaB), provide a mechanistic link between inflammation and cancer and are targets for chemoprevention. Dietary components, and human genetic variation that affects nutrient utilization, can directly modify inflammatory processes and/or suppress genomic alterations that are the molecular antecedents of cancers. The present report focuses on the convergence of genetic, nutritional, and inflammatory factors in the initiation and progression of gastrointestinal cancers, and the emerging dietary strategies for cancer prevention.

Stimulated monocyte IL-6 secretion predicts survival of patients with head and neck squamous cell carcinoma

Background

This study was performed in order to determine whether monocyte in vitro function is associated with presence, stage and prognosis of head and neck squamous cell carcinoma (HNSCC) disease.

Methods

Prospective study describing outcome, after at least five years observation, of patients treated for HNSCC disease in relation to their monocyte function. Sixty-five patients with newly diagnosed HNSCC and eighteen control patients were studied. Monocyte responsiveness was assessed by measuring levels of monocyte in vitro interleukin (IL)-6 and monocyte chemotactic peptide (MCP)-1 secretion after 24 hours of endotoxin stimulation in cultures supplied either with 20% autologous serum (AS) or serum free medium (SFM). Survival, and if relevant, cause of death, was determined at least 5 years following primary diagnosis.

Results

All patients, as a group, had higher in vitro monocyte responsiveness in terms of IL-6 (AS) (t = 2.03; p < 0.05) and MCP-1 (SFM) (t = 2.49; p < 0.05) compared to controls. Increased in vitro monocyte IL-6 endotoxin responsiveness under the SFM condition was associated with decreased survival rate (Hazard ratio (HR) = 2.27; Confidence interval (CI) = 1.05–4.88; p < 0.05). The predictive value of monocyte responsiveness, as measured by IL-6, was also retained when adjusted for age, gender and disease stage of patients (HR = 2.67; CI = 1.03–6.92; p < 0.05). With respect to MCP-1, low endotoxin-stimulated responsiveness (AS), analysed by Kaplan-Meier method, predicted decreased survival (χ = 4.0; p < 0.05).

Conclusion

In HNSCC patients, changed monocyte in vitro response to endotoxin, as measured by increased IL-6 (SFM) and decreased MCP-1 (AS) responsiveness, are negative prognostic factors.

Molecular imaging of NF-kappaB in prostate tissue after systemic administration of IL-1 beta

BACKGROUND

Activation of nuclear-factor kappaB (NF-kappaB) influences the transcription of number of genes, many of which participate in inflammatory responses and tumor development. A wide range of human cancers and inflammatory disorders express inappropriate regulation of NF-kappaB. The role of NF-kappaB in intraprostatic inflammation has not been elucidated.

METHODS

Using transgenic NF-kappaB-Luciferase Tag mice coupled to the luciferase reporter gene, we performed serial, noninvasive in vivo and ex vivo molecular imaging of NF-kappaB activation in the mouse body after systemic administration of mouse pro-inflammatory cytokines: TNF-alpha, IL-6, and IL-1 beta at 10 microg/kg body weights. In some experiments, pretreatment with dexamethasone (10 mg/kg) was used to modulate the cytokine-induced NF-kappaB-dependent luminescence in vivo.

RESULTS

Treatment of NF-kappaB-Luc mice with cytokines increased luminescence in a time- and organ- specific manner. Highest levels of NF-kappaB-dependent luminescence were observed approximately 3-4 hr after IL-1 beta administration. An important finding was the cumulative effect of IL-1 beta to activate NF-kappaB in the prostate during chronic administration.

CONCLUSIONS

The molecular imaging of NF-kappaB activity might be an attractive approach to distinguish the role of cytokine-induced NF-kappaB signaling in intraprostatic inflammation and prostate cancer development. Since dexamethasone, a known NF-kappaB inhibitor, could reduce the IL-1 beta-induced NF-kappaB-dependent luminescence in the prostate, NF-kappaB-Luc mice might be useful tool to screen potential candidate drugs for treatment of inflammation and tumor associated with aberrant NF-kappaB activity.

Reduced expression of microenvironmental Th1 cytokines accompanies adenomas-carcinomas sequence of colorectum

Cytokines have been suggested to be key factors in modulating immune response against tumorigenesis in the microenvironment. Therefore, characterization of cytokine expression along the colorectal adenoma-carcinoma sequence may add important information for understanding the immune-related mechanisms of the development of colorectal carcinoma (CRC). In this study, biopsies from 32 patients with colorectal adenoma (CRA), 20 patients with CRC and 18 healthy controls were examined. Cytokine gene expressions of interleukin-4 (IL-4), IL-10, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma and its upstream inducers (IL-12A and IL-18) were measured at messenger RNA (mRNA) level with quantitative real-time PCR (Q-PCR). Cytokine expressing cells were characterized using immunohistochemistry (IHC). A distinct different cytokine profile between adenoma and CRC was observed: the Th1 cytokines (IFN-gamma, TNF-alpha, IL-12A and IL-18) were increased in local tissues of CRA and decreased in CRC. Consistent with the quantitative cytokine data, IHC examinations revealed slightly increased densities of Th1 cytokine-expressing cells in CRA and a remarkably decreased density of the Th1 cells in CRC. In CRA, the cytokine-expressing cells were highly polarized to the subepithelial stroma while the cells were evenly distributed through the stroma in CRC. In conclusion, distinct changes in the Th1 cytokine profile appear along the colorectal adenoma-carcinoma sequence. This may reflect a change in the host immune regulatory function in the adenoma-carcinoma sequence.

Liposomal curcumin with and without oxaliplatin: effects on cell growth, apoptosis, and angiogenesis in colorectal cancer

The role of curcumin (diferuloylmethane), a proapoptotic compound, for the treatment of cancer has been an area of growing interest. Curcumin in its free form is poorly absorbed in the gastrointestinal tract and therefore may be limited in its clinical efficacy. Liposome encapsulation of this compound would allow systemic administration. The current study evaluated the preclinical antitumor activity of liposomal curcumin in colorectal cancer. We also compared the efficacy of liposomal curcumin with oxaliplatin, a standard chemotherapy for this malignancy. In vitro treatment with liposomal curcumin induced a dose-dependent growth inhibition [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium salt] and apoptosis [poly(ADP-ribose) polymerase] in the two human colorectal cancer cell lines tested (LoVo and Colo205 cells). There was also synergism between liposomal curcumin and oxaliplatin at a ratio of 4:1 in LoVo cells in vitro. In vivo, significant tumor growth inhibition was observed in Colo205 and LoVo xenografts, and the growth inhibition by liposomal curcumin was greater than that for oxaliplatin (P < 0.05) in Colo205 cells. Tumors from animals treated with liposomal curcumin showed an antiangiogenic effect, including attenuation of CD31 (an endothelial marker), vascular endothelial growth factor, and interleukin-8 expression by immunohistochemistry. This study establishes the comparable or greater growth-inhibitory and apoptotic effects of liposomal curcumin with oxaliplatin both in vitro and in vivo in colorectal cancer. We are currently developing liposomal curcumin for introduction into the clinical setting.

Intestinal epithelial cell signalling and chronic inflammation: From the proteome to specific molecular mechanisms

Advancing knowledge regarding the cellular mechanisms of intestinal inflammation has led to a better understanding of the disease pathology in patients with inflammatory bowel disease (IBD) including Crohn's disease and ulcerative colitis. It has become clear from numerous studies that enteric bacteria are a critical component in the development and prevention/treatment of chronic intestinal inflammation. An emerging new paradigm suggests that changes in the homeostasis of bacteria- and host-derived signal transduction at the intestinal epithelial cell (IEC) level may lead to a break in barrier function and the development of adaptive immune disturbances. The functional loss of anti-inflammatory host-derived signals in the gut including the immunosuppressive cytokines Interleukin 10 (IL-10) and transforming growth factor (TGF)-beta are of high relevance to the pathogenesis of IBD. The development of analytical tools including two-dimensional (2D) high-resolution protein separation techniques and peptide mass fingerprinting via high-sensitivity mass-spectrometers (MS) allows the quantitative assessment of protein expression changes in disease-relevant cell types. By using these advanced methods, the characterization of the epithelial cell proteome from murine models of experimental colitis and human IBD patients identified novel disease-related mechanisms with respect to the regulation of the glucose-regulated endoplasmic reticulum stress response protein 78 (grp-78). In conclusion, the identification and functional analysis of differentially expressed proteins in purified intestinal target cell types will help to add important insights to the understanding of the molecular pathogenesis of these immune-mediated chronic intestinal disorders.

[Stem cell theory of colorectal cancer and its connection with molecular-biological data]

Colorectal cancer is the second leading cause of death in Hungary as well as in the developed countries. The high cancer prevalence of the gastrointestinal tract is the result of the rapid turnover of epithelial cells and exposure to dietary toxins. Adult stem cells are in the lime-light of the medicine. The adult stem cells and tumor cells resemble to each other on the basis of their properties, like self-renewal and proliferation. Cancer is believed to be a disease of stem cells. Recent years have seen major advances in our understanding of location (niche), life cycle, regulation (Wnt/beta-catenin signaling pathway) and markers (mathusashi-1, beta-catenin) of gastrointestinal stem cells. The exact role of adult stem cells in intestinal carcinogenesis is open for debate. New works suggest the role for inflammation-induced engraftment of circulating marrow-derived stem cells in colorectal carcinogenesis. The causes of malignant transformation of local or engrafting bone marrow-derived stem cells are mutations (APC, MMR genes) or methylation (CDKN2A, p16/INK4a, MGMT, MLH1). The spread of dysplastic cells (bottom-up, top-down hypothesis) is also ambiguous.

Prospective study of interaction between alcohol, NSAID use and polymorphisms in genes involved in the inflammatory response in relation to risk of colorectal cancer

Inflammatory bowl disease predisposes to cancer of the colorectum, and the use of non-steroidal anti-inflammatory drugs (NSAIDs) decreases the risk; hence genetic variations that modify the inflammatory response may alter the risk of colorectal cancer (CRC). The purpose of this study was to determine if polymorphisms associated with an altered inflammatory response are associated with colorectal cancer risk, and to investigate the possible interaction with lifestyle factors such as alcohol use, smoking and NSAID use. We studied 355 adenocarcinoma cases and 753 control persons, nested within the prospective "Diet, Cancer and Health" study. None of the polymorphisms were associated with risk of colorectal cancer. A statistically significant interaction between PPARgamma2 Pro(12)Ala and alcohol was found, where alcohol use was associated with a 22% increased risk of CRC per 10g alcohol/day among carriers of the variant allele but not among homozygous wild type allele carriers (P for interaction=0.02). Moreover, an interaction between DLG5 R30Q and NSAID use was found (P for interaction=0.02). Our results do not suggest that inborn variations in the inflammatory response play any major role in risk of colorectal cancer.

The role of STAT1/IRF-1 on synergistic ROS production and loss of mitochondrial transmembrane potential during hepatic cell death induced by LPS/d-GalN

Previously, we demonstrated that signal transducer and activator of transcription factor 1 (STAT1) plays an essential role in liver injury induced by lipopolysaccharide (LPS)/D-galactosamine (D-GalN); however, the underlying mechanism involved remains unclear. Here, we showed that LPS/D-GalN administration induced secretion of tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma), which mediated apoptosis synergistically. Moreover, LPS/D-GalN-induced apoptosis was associated with increased inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production, as well as elevated reactive oxygen species (ROS) production, which were all strongly inhibited by treatment with the antioxidant N-acetyl-L-cysteine (NAC) and an iNOS/NO inhibitor, L-NMMA. Although STAT1 activation and expression did not change significantly in TNF-alpha/IFN-gamma-cotreated cells compared with cells treated with IFN-gamma alone, the absence of STAT1 or interferon regulatory factor 1 (IRF-1) in genetic knockout mice strongly abrogated the observed effects of TNF-alpha/IFN-gamma on iNOS/NO induction, ROS production, loss of mitochondrial transmembrane potential (DeltaPsim), and apoptosis compared with STAT1(+/+) and IRF-1(+/+) mice. Additionally, the synergistic effects of TNF-alpha/IFN-gamma on iNOS/NO induction, ROS production, and apoptosis were significantly inhibited by overexpression of dominant negative STAT1 in contrast to overexpression of wild-type STAT1. In STAT1-deficient mice, nuclear factor kappaB (NF-kappaB) activation by TNF-alpha/IFN-gamma was attenuated and strongly inhibited by both NAC and L-NMMA. Moreover, the proteasome inhibitor, MG132, inhibited NF-kappaB activation and strongly inhibited iNOS/NO induction, ROS production, and loss of DeltaPsim induced by TNF-alpha/IFN-gamma, thereby inhibiting apoptosis. Interestingly, it appears peroxynitrite, which is produced by TNF-alpha/IFN-gamma, may interfere with STAT1 phosphorylation by inducing STAT1 nitration. Collectively, these findings demonstrate that TNF-alpha/IFN-gamma synergistically potentiates iNOS/NO induction, ROS production, and loss of DeltaPsim via STAT1 overexpression, playing an important role in promoting apoptosis and liver injury induced by LPS/D-GalN.

The intestinal epithelial barrier: how to distinguish between the microbial flora and pathogens

The gastrointestinal tract is fundamental for the uptake of nutrients and fluids, but it also represents the greatest surface of the body in contact with the external environment and most human pathogens enter the body through the mucosal surface, especially in the intestine. The intestinal immune system protects the sterile core of the organism against invasion and systemic dissemination of both pathogens and limits for level penetration of commensal microorganisms. In addition, the human intestine is continually in contact with 10(14) commensal bacteria containing more than 500 different species. These commensal bacteria confer health benefits to their host by helping dietary digestion, development of gut immunity and preventing colonization by pathogens. To maintain integrity and normal function of intestine, a delicate equilibrium must be reached between the bacterial flora and intestinal immune system. This review discusses the recent advances in our understanding of how the mucosal intestinal barrier maintains a local homeostatic response to the resident intestinal bacteria, while protecting the host against enteric pathogens. In particular, the emerging function of Toll-like receptors (TLRs) and Nod-like receptors (NLRs) in controlling mucosal immunity will be presented.

Transcripts targeted by the microRNA-16 family cooperatively regulate cell cycle progression

microRNAs (miRNAs) are abundant, approximately 21-nucleotide, noncoding regulatory RNAs. Each miRNA may regulate hundreds of mRNA targets, but the identities of these targets and the processes they regulate are poorly understood. Here we have explored the use of microarray profiling and functional screening to identify targets and biological processes triggered by the transfection of human cells with miRNAs. We demonstrate that a family of miRNAs sharing sequence identity with miRNA-16 (miR-16) negatively regulates cellular growth and cell cycle progression. miR-16-down-regulated transcripts were enriched with genes whose silencing by small interfering RNAs causes an accumulation of cells in G(0)/G(1). Simultaneous silencing of these genes was more effective at blocking cell cycle progression than disruption of the individual genes. Thus, miR-16 coordinately regulates targets that may act in concert to control cell cycle progression.

Colon cancer, fatty acids and anti-inflammatory compounds

PURPOSE OF REVIEW

To outline recent findings on the efficacy of n-3 polyunsaturated fatty acids in the prevention/treatment of inflammatory bowel disease and colorectal cancer.

RECENT FINDINGS

Compelling data indicate a functional link between chronic inflammation and colon cancer. With respect to environmental risk factors, there is growing evidence that long-chain n-3 polyunsaturated fatty acids found in fish oil suppress inflammatory bowel diseases and colon cancer risk in humans. Unfortunately, the molecular basis of the effect of n-3 polyunsaturated fatty acids on inflammation/colitis-associated colon cancer risk is still largely obscure. In this review, we focus on recent studies which address three emerging mechanisms of n-3 polyunsaturated fatty acids action: (1) metabolic interconversion into bioactive eicosanoids, (2) modulation of nuclear receptor activation, and (3) alteration of membrane phospholipid composition and functionality of lipid microdomains.

SUMMARY

The consumption of dietary fish oil may prove to be an effective adjuvant therapy in colon cancer. Therefore, it is both appropriate and timely to determine precisely how n-3 polyunsaturated fatty acids modulate cell signaling networks, and reduce the risk of developing colon cancer and inflammatory disorders of the intestine.