Infliximab does not increase colonic cancer risk associated to murine chronic colitis.

AIM: To explore the influence of Infliximab (IFX) on cancer progression in a murine model of colonic cancer associated to chronic colitis. METHODS: AOM/DSS model was induced in C57BL/6 mice. Mice were injected with IFX (5 mg/kg) during each DSS cycle while control mice received saline. Body weight, occult blood test and stool consistency were measured to calculate the disease activity index (DAI). Mice were sacrificed at week 10 and colons were analyzed macroscopically and microscopically for number of cancers and degree of inflammation. MTT assay was performed on CT26 to evaluate the potential IFX role on metabolic activity and proliferation. Cells were incubated with TNF-α or IFX or TNF-α plus IFX, and cell vitality was evaluated after 6, 24 and 48 h. The same setting was used after pre-incubation with TNF-α for 24 h. RESULTS: IFX significantly reduced DAI and body weight loss in mice compared with controls, preserving also colon length at sacrifice. Histological score was also reduced in treated mice. At macroscopic analysis, IFX treated mice showed a lower number of tumor lesions compared to controls. This was confirmed at microscopic analysis, although differences were not statistically significant. In vitro, IFX treated CT26 maintained similar proliferation ability at MTT test, both when exposed to IFX alone and when associated to TNF-α. CONCLUSION: IFX did not increase colonic cancer risk in AOM-DSS model of cancer on chronic colitis nor influence directly the proliferation of murine colon cancer epithelial cells.

Aspirin prevents colorectal cancer metastasis in mice by splitting the crosstalk between platelets and tumor cells.

We investigated whether platelets prime colon cancer cells for metastasis and whether pharmacological inhibition of platelet function may prevent it. Coculturing HT29 human colon carcinoma cells with human platelets led to the induction of mesenchymal-like cancer cells characterized by downregulation of E-cadherin and upregulation of Twist1, enhanced cell mobility and a proaggregatory action on platelets. These changes were prevented by different antiplatelet agents, aspirin[an inhibitor of cyclooxygenase(COX)-1], DG-041[an antagonist of prostaglandin(PG)E2 EP3 receptor] and ticagrelor (a P2Y12 receptor antagonist). The injection of HT29 cells, exposed to platelets in vitro, into the tail vein of humanized immunodeficient mice led to higher incidence of lung metastasis compared to the injection of untreated HT29 cells. This effect was associated with enhanced systemic biosynthesis of thromboxane(TX)A2 and PGE2in vivo. Platelet COX-1 inhibition by aspirin administration to mice prevented the increased rate of metastasis as well as the enhanced production of TXA2 and PGE2 induced by the in vitro priming of HT29 cells by platelets. In conclusion, targeting platelet COX-1 with low-dose aspirin exerts an antimetastatic action by averting the stem cell mimicry of cancer cells associated with enhanced proaggregatory effects induced by platelet-tumor cell interactions. These effects may be shared by other antiplatelet drugs.

Gelatin tannate ameliorates acute colitis in mice by reinforcing mucus layer and modulating gut microbiota composition: Emerging role for 'gut barrier protectors' in IBD?

BACKGROUND: Gelatin tannate, a gelatin powder containing tannic acids, is commonly employed as an intestinal astringent. Neither information nor animal model exist to confirm its efficacy or unravel mechanisms of action. OBJECTIVE: To evaluate the action of gelatin tannate in murine dextran sodium sulphate (DSS)-induced acute colitis. METHODS: Mice were exposed to DSS and received gelatin tannate by gavage. At sacrifice, colon histological degree of inflammation was assessed. Stool samples were cultured for microbiological analysis. Colon samples were analysed by two-photon confocal microscopy and atomic force microscopy. Elisa was performed on murine serum to assess lipopolysaccharide and peptidoglycan levels. RESULTS: Gelatin tannate treatment reduced disease activity, bodyweight loss, and preserved colonic length. It produced a decrease in the amount of enterobacteria and enterococci. At confocal microscopy, intestinal samples from healthy and treated mice displayed similar structure in mucus layer thickness and composition; samples from placebo group had no mucus layer or a thinner stratus. Atomic force microscopy confirmed these findings. Treated mice showed lower blood LPS levels vs. control. CONCLUSIONS: Gelatin tannate decreased the severity of colitis. Acting as a gut barrier enhancer, it re-establishes gut homeostasis by recovering intestinal permeability and mucus layer integrity in gut mucosa and by modulating microbiota composition.

Cancer stem cells in colorectal cancer from pathogenesis to therapy: controversies and perspectives.

Colorectal cancer remains one of the most common and lethal malignancies worldwide despite the use of various therapeutic strategies. A better understanding of the mechanisms responsible for tumor initiation and progression is essential for the development of novel, more powerful therapies. The traditional, so-called "stochastic model" of tumor development, which assumes that each cancer cell is tumorigenic, has been deeply challenged during the past decade by the identification of cancer stem cells (CSCs), a biologically distinct subset of cells within the bulk of tumor mass. This discovery led to the development of the hierarchical model of tumorigenesis which assumes that only CSCs have the ability to initiate tumor growth, both at primary and metastatic sites. This model implies that the elimination of all CSCs is fundamental to eradicate tumors and that failure to do so might be responsible for the occurrence of relapses and/or metastases frequently observed in the clinical management of colorectal cancer patients. Identification and isolation of CSCs is essential for a better understanding of their role in the tumorigenetic process and for the development of CSC-specific therapies. Several methods have been used for this purpose and many efforts have been focused on the identification of specific CSC-surface markers. This review provides an overview of the proposed roles of CSC in human colorectal tumorigenesis focusing on the most important molecules identified as CSC-specific markers in colorectal cancer and on the potential strategies for the development of CSC-targeted therapy.

Locally injected Infliximab ameliorates murine DSS colitis: differences in serum and intestinal levels of drug between healthy and colitic mice.

BACKGROUND: Infliximab is effective in human and murine IBD, but its pharmacodynamic is still poorly known. The aim of this study was to assess the affinity of infliximab to murine TNF-α, its role in murine colitis when administered intra-rectally and its levels in the blood, gut mucosa and stool of healthy and sick mice. METHODS: An ELISA kit was built in order to assess the affinity of infliximab to human or murine-TNF-α. Human IgG were used as controls. DSS model of colitis on C57BL/6 mice was used to assess clinical efficacy of infliximab administered intravenously or by enema. Stool, serum and colon samples were collected to assess infliximab levels and histology for Rachmilewitz score. RESULTS: Infliximab showed a good affinity both for human-TNF-α and murine-TNF-α. In DSS colitic mice infliximab ameliorated the severity of colitis, regardless of the administration route. In comparison with colitic mice, healthy mice displayed higher serum and mucosal infliximab levels, while detectable levels of infliximab were found in faeces, particularly in colitic mice. CONCLUSION: Our data support murine models to study infliximab pharmacokinetics and dynamics. Measurable levels of infliximab can be found at different concentrations in blood, intestinal mucosa and stool from healthy and sick mice, thus infliximab pharmacokinetics could have a major impact in human IBD.

Rhodium and iridium salts inhibit proliferation and induce DNA damage in rat fibroblasts in vitro.

Environmental concentration of the platinum group elements is increased in the last years due to their use in automobile catalytic converters. Limited data are available on the effects of such elements at a cellular level and on their toxicity, especially for rhodium and iridium which have been more recently introduced in use. The toxic effects of rhodium and iridium salts were analyzed on a normal diploid rat fibroblast cell line in vitro. Both salts halted cell growth in a dose- and time-dependent fashion by inhibiting cell cycle progression, inducing apoptosis and modulating the expression of cell cycle regulatory proteins. In fact, they both caused an accumulation of cells in the G2/M phase of the cell cycle and affected the expression levels of pRb, cyclins D1 and E, p21(Waf1) and p27(Kip1). DNA strand breaks, as assessed by comet test, and an increase in the intracellular levels of reactive oxygen species also occurred in exposed cell cultures. These findings suggest a potential toxicity of both iridium and rhodium salts and emphasize the need for further studies to understand their effects at a cellular level to enable a better assessment of their toxic effects and to identify ways for their modulation and/or prevention.

Differential CD133 expression pattern during mouse colon tumorigenesis.

BACKGROUND/AIM: The cancer stem cell model suggests that only a rare subpopulation, known as cancer stem cells (CSC) are responsible for tumor initiation. CSC from several human carcinomas are characterized by specific cell surface markers, such as CD133. The CD133 role in colon tumorigenesis remains controversial. MATERIALS AND METHODS: CD133 was evaluated by immunohistochemistry in a mouse model of colitis-related colon tumorigenesis induced by a combined treatment with azoxymethane (AOM) and dextran sodium sulphate (DSS). RESULTS: In normal tissue rare scattered positive cells were detectable at the bottom of the crypts. The percentage of positive cells significantly increased in dysplastic lesions and appeared to progressively decrease in the passage from dysplasia to adenoma and then to cancer, although always remaining greater in number than in the normal tissue. CONCLUSION: An increased CD133 expression occurs at early stages of colon tumorigenesis in the mouse. CD133-expressing cells might play an important role from the earlier phase and throughout the entire process of colon cancer development.