Maternal exposure to a human relevant mixture of persistent organic pollutants reduces colorectal carcinogenesis in A/J Min/+ mice.

An increased risk of developing colorectal cancer has been associated with exposure to persistent organic pollutants (POPs) and alteration in the gut bacterial community. However, there is limited understanding about the impact of maternal exposure to POPs on colorectal cancer and gut microbiota. This study characterized the influence of exposure to a human relevant mixture of POPs during gestation and lactation on colorectal cancer, intestinal metabolite composition and microbiota in the A/J Min/+ mouse model. Surprisingly, the maternal POP exposure decreased colonic tumor burden, as shown by light microscopy and histopathological evaluation, indicating a restriction of colorectal carcinogenesis. 1H nuclear magnetic resonance spectroscopy-based metabolomic analysis identified alterations in the metabolism of amino acids, lipids, glycerophospholipids and energy in intestinal tissue. In addition, 16S rRNA sequencing of gut microbiota indicated that maternal exposure modified fecal bacterial composition. In conclusion, the results showed that early-life exposure to a mixture of POPs reduced colorectal cancer initiation and promotion, possibly through modulation of the microbial and biochemical environment. Further studies should focus on the development of colorectal cancer after combined maternal and dietary exposures to environmentally relevant low-dose POP mixtures.

Fasting Serum Levels of Potassium and Sodium in Relation to Long-Term Risk of Cancer in Healthy Men.

PURPOSE: To examine whether serum levels of potassium and sodium were associated with long-term cancer risk in initially healthy men. PATIENTS AND METHODS: A cohort of 1994 initially healthy men with no use of medication, aged 40-59 years, was followed for cancer during 40 years of follow-up. Associations between fasting electrolyte levels and cancer risk were assessed with incidence rates and Cox proportional hazards models. RESULTS: Potassium, but not sodium, was linearly associated with cancer risk. This association remained significant after adjustment of several potential confounding factors, and also after excluding the first 10 years of follow-up. The age-adjusted risk of all-site cancer increased with 16% for each SD increase in potassium level. Men with hyperkalemia showed an incidence rate that was 40% higher than for men with normal potassium levels. CONCLUSION: Fasting serum potassium level in healthy men was positively associated with long-term cancer risk. Potassium or potassium ion channels may have a role in cell proliferation or differentiation. These findings might imply future cancer strategies for targeting individuals with high serum potassium levels.

The Agaricus blazei-Based Mushroom Extract, Andosan™, Protects against Intestinal Tumorigenesis in the A/J Min/+ Mouse.

BACKGROUND: The novel A/J Min/+ mouse, which is a model for human Familial Adenomatous Polyposis (FAP), develops spontaneously multiple adenocarcinomas in the colon as well as in the small intestine. Agaricus blazei Murill (AbM) is an edible Basidiomycetes mushroom that has been used in traditional medicine against cancer and other diseases. The mushroom contains immunomodulating ß-glucans and is shown to have antitumor effects in murine cancer models. Andosan™ is a water extract based on AbM (82%), but it also contains the medicinal Basidiomycetes mushrooms Hericeum erinaceus and Grifola frondosa. METHODS AND FINDINGS: Tap water with 10% Andosan™ was provided as the only drinking water for 15 or 22 weeks to A/J Min/+ mice and A/J wild-type mice (one single-nucleotide polymorphism (SNP) difference), which then were exsanguinated and their intestines preserved in formaldehyde and the serum frozen. The intestines were examined blindly by microscopy and also stained for the tumor-associated protease, legumain. Serum cytokines (pro- and anti-inflammatory, Th1-, Th2 -and Th17 type) were measured by Luminex multiplex analysis. Andosan™ treated A/J Min/+ mice had a significantly lower number of adenocarcinomas in the intestines, as well as a 60% significantly reduced intestinal tumor load (number of tumors x size) compared to control. There was also reduced legumain expression in intestines from Andosan™ treated animals. Moreover, Andosan™ had a significant cytotoxic effect correlating with apoptosis on the human cancer colon cell line, Caco-2, in vitro. When examining serum from both A/J Min/+ and wild type mice, there was a significant increase in anti-tumor Th1 type and pro-inflammatory cytokines in the Andosan™ treated mice. CONCLUSIONS: The results from this mouse model for colorectal cancer shows significant protection of orally administered Andosan™ against development of intestinal cancer. This is supported by the finding of less legumain in intestines of Andosan™ treated mice and increased systemic Th1 cytokine response. The mechanism is probably both immuno-modulatory and growth inhibition of tumor cells by induction of apoptosis.

Protein kinase A antagonist inhibits ß-catenin nuclear translocation, c-Myc and COX-2 expression and tumor promotion in Apc(Min/+) mice.

BACKGROUND: The adenomatous polyposis coli (APC) protein is part of the destruction complex controlling proteosomal degradation of ß-catenin and limiting its nuclear translocation, which is thought to play a gate-keeping role in colorectal cancer. The destruction complex is inhibited by Wnt-Frz and prostaglandin E(2) (PGE(2)) - PI-3 kinase pathways. Recent reports show that PGE(2)-induced phosphorylation of ß-catenin by protein kinase A (PKA) increases nuclear translocation indicating two mechanisms of action of PGE(2) on ß-catenin homeostasis. FINDINGS: Treatment of Apc(Min/+) mice that spontaneously develop intestinal adenomas with a PKA antagonist (Rp-8-Br-cAMPS) selectively targeting only the latter pathway reduced tumor load, but not the number of adenomas. Immunohistochemical characterization of intestines from treated and control animals revealed that expression of ß-catenin, ß-catenin nuclear translocation and expression of the ß-catenin target genes c-Myc and COX-2 were significantly down-regulated upon Rp-8-Br-cAMPS treatment. Parallel experiments in a human colon cancer cell line (HCT116) revealed that Rp-8-Br-cAMPS blocked PGE(2)-induced ß-catenin phosphorylation and c-Myc upregulation. CONCLUSION: Based on our findings we suggest that PGE(2) act through PKA to promote ß-catenin nuclear translocation and tumor development in Apc(Min/+) mice in vivo, indicating that the direct regulatory effect of PKA on ß-catenin nuclear translocation is operative in intestinal cancer.