Cytokines, inflammation and colon cancer

Overexpression of IFITM1 has clinicopathologic effects on gastric cancer and is regulated by an epigenetic mechanism

In an effort to identify novel genes related to the prognosis of gastric cancer, we performed gene expression profiling and found overexpressed levels of human interferon-induced transmembrane protein 1 (IFITM1). We validated the gastric cancer-specific up-regulation of IFITM1 and its association with cancer progression. We also studied its epigenetic regulation and tumorigenesis-related functions. Expression of IFITM1 was evaluated in various human gastric cancer cells and in 35 patient tumor tissues by quantitative RT-PCR and Western blot analyses. The results showed highly up-regulated IFITM1 in cancer cell lines and tissues. Furthermore, IHC studies were performed on 151 patient tissues, and a significant correlation was revealed between higher IFITM1 expression and Lauren's intestinal type (P = 0.007) and differentiated adenocarcinoma (P = 0.025). Quantitative studies of DNA methylation for 27 CpG sites in the regulatory region showed hypermethylation in cells expressing low levels of IFITM1. Methylation-dependent IFITM1 expression was confirmed further by in vitro demethylation using 5-aza-2'-deoxycytidine and luciferase assays. The functional analysis of IFITM1 by silencing of its expression with small-interfering RNA showed decreased migration and invasiveness of cancer cells, whereas its overexpression exhibited the opposite results. In this study, we demonstrated gastric cancer-specific overexpression of IFITM1 regulated by promoter methylation and the role of IFITM1 in cancer prognosis.

Differential effects of selenium and knock-down of glutathione peroxidases on TNFα and flagellin inflammatory responses in gut epithelial cells

Selenium (Se) is essential for human health. Despite evidence that Se intake affects inflammatory responses, the mechanisms by which Se and the selenoproteins modulate inflammatory signalling, especially in the gut, are not yet defined. The aim of this work was to assess effects of altered Se supply and knock-down of individual selenoproteins on NF-κB activation in gut epithelial cells. Caco-2 cells were stably transfected with gene constructs expressing luciferase linked either to three upstream NF-κB response elements and a TATA box or only a TATA box. TNFα and flagellin activated NF-κB-dependent luciferase activity and increased IL-8 expression. Se depletion decreased expression of glutathione peroxidase1 (GPX1) and selenoproteins H and W and increased TNFα-stimulated luciferase activity, endogenous IL-8 expression and reactive oxygen species (ROS) production. These effects were not mimicked by independent knock-down of either GPX1, selenoprotein H or W; indeed, GPX1 knock-down lowered TNFα-induced NF-κB activation and did not affect ROS levels. GPX4 knock-down decreased NF-κB activation by flagellin but not by TNFα. We hypothesise that Se depletion alters the pattern of expression of multiple selenoproteins that in turn increases ROS and modulates NF-κB activation in epithelial cells, but that the effect of GPX1 knock-down is ROS-independent.

The intestinal microbiota, gastrointestinal environment and colorectal cancer: a putative role for probiotics in prevention of colorectal cancer?

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States, and, even though 5-15% of the total CRC cases can be attributed to individual genetic predisposition, environmental factors could be considered major factors in susceptibility to CRC. Lifestyle factors increasing the risks of CRC include elevated body mass index, obesity, and reduced physical activity. Additionally, a number of dietary elements have been associated with higher or lower incidence of CRC. In this context, it has been suggested that diets high in fruit and low in meat might have a protective effect, reducing the incidence of colorectal adenomas by modulating the composition of the normal nonpathogenic commensal microbiota. In addition, it has been demonstrated that changes in abundance of taxonomic groups have a profound impact on the gastrointestinal physiology, and an increasing number of studies are proposing that the microbiota mediates the generation of dietary factors triggering colon cancer. High-throughput sequencing and molecular taxonomic technologies are rapidly filling the knowledge gaps left by conventional microbiology techniques to obtain a comprehensive catalog of the human intestinal microbiota and their associated metabolic repertoire. The information provided by these studies will be essential to identify agents capable of modulating the massive amount of gut bacteria in safe noninvasive manners to prevent CRC. Probiotics, defined as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host" (219), are capable of transient modulation of the microbiota, and their beneficial effects include reinforcement of the natural defense mechanisms and protection against gastrointestinal disorders. Probiotics have been successfully used to manage infant diarrhea, food allergies, and inflammatory bowel disease; hence, the purpose of this review was to examine probiotic metabolic activities that may have an effect on the prevention of CRC by scavenging toxic compounds or preventing their generation in situ. Additionally, a brief consideration is given to safety evaluation and production methods in the context of probiotics efficacy.

The role of interleukin DNA polymorphisms in gastric cancer

Gastric carcinoma is one of the most widespread malignancies worldwide. Interleukins are the key group of cytokines which may have tumor-promoting or tumor-suppressing effect, and receptors for them, of course, have the same importance in this context. However, mechanisms of their impact on tumor are not fully understood up to date. Numerous studies provide conflicting data, that makes picture more confusing and complicated. It is known that single nucleotide polymorphisms in interleukin genes may dramatically affect on protein expression level, or alter its functions, which may lead to gastritis or ulcer, and eventually promote cancer occurrence. Furthermore, some of these genetic polymorphisms may serve as predictive factors for cancer prognosis and prevention. In order to understand the impact of each genetic polymorphism, the review of IL-1B, IL-4, IL-6, IL-8, IL-10, IL17A, IL-17F DNA polymorphisms on gastric carcinoma was done, and risk alleles were recommended for further research.

Prevention of colitis-associated colorectal cancer with 8-hydroxydeoxyguanosine

Colitis-associated cancer (CAC) is one of clear examples of inflammation-carcinogenesis sequence, by which the strict control of colitis with potent anti-inflammatory or antioxidative agent offers the chance of cancer prevention. Supported with the facts that Rac1 binds and activates STAT3, which are significantly upregulated in inflammatory bowel disease (IBD) as well as CAC, but 8-hydroxydeoxyguanosine (8-oxo-7,8-dihydrodeoxyguanosine or 8-OHdG) paradoxically can block Rac1 activation and subsequent NADPH oxidase (NOX) inactivation in various inflammation models, we hypothesized that attenuated Rac1-STAT3 and COX-NF-κB pathway by exogenous 8-OHdG administration may ameliorate inflammatory signaling in dextran sodium sulfate (DSS)-induced colitis and can prevent CAC. Before commencing carcinogenesis model, we checked whether exogenous 8-OHdG can alleviate IBD, for which interleukin (IL)-10 knockout mice were designed to ingest 5% DSS for 1 week, and 8-OHdG is given through intraperitoneal route daily. 8-OHdG treatment groups significantly reduced pathologic grade of DSS-induced colitis as well as various inflammatory mediators such as TNF-α, IL-6, COX-2, and iNOS in a dose-dependent manner. To document the cancer prevention effects of 8-OHdG, mice were injected azoxymethane followed by drinking 2.5% DSS for 1 week, after which 8-OHdG-containing diets were given for 20 weeks. As results, mice that consumed 8-OHdG-containing diet significantly reduced both tumor incidence and multiplicity. Rac1 activity and phosphorylated STAT3 level were significantly attenuated in the 8-OHdG-treated group. Significantly decreased levels of malondialdehyde, monocyte chemotactic protein-1, matrix metalloproteinasess, COX-2, NOX4, and β-catenin nuclear accumulation were responsible for cancer prevention effects of exogenous 8-OHdG. In conclusion, we clearly showed cancer-preventive effect of exogenous 8-OHdG against CAC.