Intestinal Microbes, Diet, and Colorectal Cancer

The Interplay between Microbiota and Chemotherapy-Derived Metabolites in Breast Cancer

The most common cancer in women is breast cancer, which is also the second leading cause of death in this group. It is, however, important to note that some women will develop or will not develop breast cancer regardless of whether certain known risk factors are present. On the other hand, certain compounds are produced by bacteria in the gut, such as short-chain fatty acids, secondary bile acids, and other metabolites that may be linked to breast cancer development and mediate the chemotherapy response. Modeling the microbiota through dietary intervention and identifying metabolites directly associated with breast cancer and its complications may be useful to identify actionable targets and improve the effect of antiangiogenic therapies. Metabolomics is therefore a complementary approach to metagenomics for this purpose. As a result of the combination of both techniques, a better understanding of molecular biology and oncogenesis can be obtained. This article reviews recent literature about the influence of bacterial metabolites and chemotherapy metabolites in breast cancer patients, as well as the influence of diet.

Novel Biomarkers of Habitual Alcohol Intake and Associations With Risk of Pancreatic and Liver Cancers and Liver Disease Mortality

BACKGROUND

Alcohol is an established risk factor for several cancers, but modest alcohol-cancer associations may be missed because of measurement error in self-reported assessments. Biomarkers of habitual alcohol intake may provide novel insight into the relationship between alcohol and cancer risk.

METHODS

Untargeted metabolomics was used to identify metabolites correlated with self-reported habitual alcohol intake in a discovery dataset from the European Prospective Investigation into Cancer and Nutrition (EPIC; n = 454). Statistically significant correlations were tested in independent datasets of controls from case-control studies nested within EPIC (n = 280) and the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC; n = 438) study. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations of alcohol-associated metabolites and self-reported alcohol intake with risk of pancreatic cancer, hepatocellular carcinoma (HCC), liver cancer, and liver disease mortality in the contributing studies.

RESULTS

Two metabolites displayed a dose-response association with self-reported alcohol intake: 2-hydroxy-3-methylbutyric acid and an unidentified compound. A 1-SD (log2) increase in levels of 2-hydroxy-3-methylbutyric acid was associated with risk of HCC (OR = 2.54, 95% CI = 1.51 to 4.27) and pancreatic cancer (OR = 1.43, 95% CI = 1.03 to 1.99) in EPIC and liver cancer (OR = 2.00, 95% CI = 1.44 to 2.77) and liver disease mortality (OR = 2.16, 95% CI = 1.63 to 2.86) in ATBC. Conversely, a 1-SD (log2) increase in questionnaire-derived alcohol intake was not associated with HCC or pancreatic cancer in EPIC or liver cancer in ATBC but was associated with liver disease mortality (OR = 2.19, 95% CI = 1.60 to 2.98) in ATBC.

CONCLUSIONS

2-hydroxy-3-methylbutyric acid is a candidate biomarker of habitual alcohol intake that may advance the study of alcohol and cancer risk in population-based studies.

Inflammation, It's Regulation and Antiphlogistic Effect of the Cyanogenic Glycoside Amygdalin

The inflammatory reaction accompanies in part or in full any disease process in the vascularized metazoan. This complicated reaction is controlled by regulatory mechanisms, some of which produce unpleasant symptomatic manifestations of inflammation. Therefore, there has been an effort to develop selective drugs aimed at removing pain, fever, or swelling. Gradually, however, serious adverse side effects of such inhibitors became apparent. Scientific research has therefore continued to explore new possibilities, including naturally available substances. Amygdalin is a cyanogenic glycoside present, e.g., in bitter almonds. This glycoside has already sparked many discussions among scientists, especially about its anticancer potential and related toxic cyanides. However, toxicity at different doses made it generally unacceptable. Although amygdalin given at the correct oral dose may not lead to poisoning, it has not yet been accurately quantified, as its action is often affected by different intestinal microbial consortia. Its pharmacological activities have been studied, but its effects on the body's inflammatory response are lacking. This review discusses the chemical structure, toxicity, and current knowledge of the molecular mechanism of amygdalin activity on immune functions, including the anti-inflammatory effect, but also discusses inflammation as such, its mediators with diverse functions, which are usually targeted by drugs.

Computational studies on bacterial secondary metabolites against breast cancer

Microbes exist in the human body provide more benefits by modulating metabolic processes, immunity, and signal transduction. However, microbial dysbiosis with harmful bacterial species can cause chronic inflammation and cancers. Hence human probiotics were recently paid more attention to immune responses, therapy, and diagnosis. Breast cancer is the second leading cancer worldwide and causes more death in women. The role of breast microbiome secondary metabolites in breast cancer is poorly studied. Research shows that breast has a specific microbiome inhabited with particular bacterial species. More significantly probiotics produced from breast microbiomes may act as a potential biomarker for breast cancer diagnosis. Hence this computational research aimed at the effect of chosen metabolites on breast cancer cell receptor G-protein-coupled bile acid receptor, Gpbar1 (TGR5). The current research suggested that cadaverine, succinate, p-cresol, and its derivatives could be used as a molecular marker in the diagnosis of breast cancer.

Red and processed meat consumption within two different dietary patterns: Effect on the colon microbial community and volatile metabolites in pigs

Pigs were fed either red and processed meat or chicken meat within either a prudent or a Western dietary pattern for four weeks (2 × 2 full factorial design). The colon microbial community and volatile organic compounds were assessed (either quantified or based on their presence). Results show that Lactobacilli were characteristic for the chicken × prudent dietary pattern treatment and Paraprevotella for the red and processed meat × prudent dietary pattern treatment. Enterobacteriaceae and Desulfovibrio were characteristic for the chicken × Western dietary pattern treatment and Butyrivibrio for the red and processed meat × Western dietary pattern treatment. Campylobacter was characteristic for chicken consumption and Clostridium XIVa for red and processed meat, irrespective of the dietary pattern. Ethyl valerate and 1-methylthio-propane were observed more frequently in pigs fed red and processed meat compared to chicken meat. The prevalence of 3-methylbutanal was >80% for pigs receiving a Western dietary pattern, whereas for pigs fed a prudent dietary pattern the prevalence was <35%. The concentration of butanoic acid was significantly higher when the prudent dietary pattern was given, compared to the Western dietary pattern, but no differences for other short chain fatty acids or protein fermentation products were observed.

Effects of the Gut microbiota on Amygdalin and its use as an anti-cancer therapy: Substantial review on the key components involved in altering dose efficacy and toxicity

Conventional and Alternative Medicine (CAM) is popularly used due to side-effects and failure of approved methods, for diseases like Epilepsy and Cancer. Amygdalin, a cyanogenic diglycoside is commonly administered for cancer with other CAM therapies like vitamins and seeds of fruits like apricots and bitter almonds, due to its ability to hydrolyse to hydrogen cyanide (HCN), benzaldehyde and glucose. Over the years, several cases of cyanide toxicity on ingestion have been documented. In-vitro and in-vivo studies using various doses and modes of administration, like IV administration studies that showed no HCN formation, point to the role played by the gut microbiota for the commonly seen poisoning on consumption. The anaerobic Bacteriodetes phylum found in the gut has a high β-glucosidase activity needed for amygdalin hydrolysis to HCN. However, there are certain conditions under which these HCN levels rise to cause toxicity. Case studies have shown toxicity on ingestion of variable doses of amygdalin and no HCN side-effects on consumption of high doses. This review shows how factors like probiotic and prebiotic consumption, other CAM therapies, obesity, diet, age and the like, that alter gut consortium, are responsible for the varying conditions under which toxicity occurs and can be further studied to set-up conditions for safe oral doses. It also indicates ways to delay or quickly treat cyanide toxicity due to oral administration and, reviews conflicts on amygdalin's anti-cancer abilities, dose levels, mode of administration and pharmacokinetics that have hindered its official acceptance at a therapeutic level.

Effect of diet and gut environment on the gastrointestinal formation of N-nitroso compounds: A review

Diet is associated with the development of cancer in the gastrointestinal (GI) tract, because dietary nitrate and nitrite are the main nitrosating agents that are responsible for the formation of carcinogenic N-nitroso compounds (NOCs) when nitrosatable substrates, such as amine and amide, are present in the GI tract. However, whether the nitroso compounds become beneficial S-nitroso compounds or carcinogenic NOCs might depend on dietary and environmental factors including food stuffs, gastric acidity, microbial flora, and the mean transit time of digesta. This review focused on GI NOC formation and environmental risk factors affecting its formation to provide appropriate nutritional strategies to prevent the development of GI cancer.

Diet and colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is the third most common diagnosed cancer in men and the second in women. Dietary factors and lifestyle may contribute to the increasing CRC incidence, making these issues interesting for both the general population and the medical oncology community.

OBJECTIVE

The aim of this report is to present a review of the published epidemiologic research to date reflecting the most current scientific evidence related to diet and CRC risk.

DESIGN

EMBASE and PubMed-NCBI were searched for relevant articles up to November 2014 that identified potential interactions between foods or dietary patterns and CRC risk.

RESULTS

Obesity increases the risk of CRC by 19%. Regular physical activity reduces this risk by 24%. CRC risk derived from red meat intake is influenced by both total intake and its frequency. Fish consumption may decrease CRC risk by 12% whereas garlic intake is not significantly associated with reduced CRC risk. Intakes of more than 20g/day of fiber are associated with a 25% reduction of CRC risk and 525mL/day of milk reduces colon cancer risk by 26% in men. Moderate amounts of alcohol (25-30g/day) increase CRC risk.

CONCLUSIONS

CRC is a preventable disease through the modification of associated risk factors, including physical inactivity, obesity and overweight, excessive meat intake, smoking and alcoholic beverage consumption. Nonetheless, epidemiological evidence in this regard is not conclusive so further research is warranted.