Dietary legumes, intestinal microbiota, inflammation and colorectal cancer

Differences in the molecular organisation of tumours along the colon are linked to interactions within the tumour ecosystem

Tumours exhibit significant heterogeneity in their molecular profiles across patients, largely influenced by the tissue of origin, where certain driver gene mutations are predominantly associated with specific cancer types. Here, we unveil an additional layer of complexity: some cancer types display anatomic location-specific mutation profiles akin to tissue-specificity. To better understand this phenomenon, we concentrate on colon cancer. While prior studies have noted changes of the frequency of molecular alterations along the colon, the underlying reasons and whether those changes occur rather gradual or are distinct between the left and right colon, remain unclear. Developing and leveraging stringent statistical models on molecular data from 522 colorectal tumours from The Cancer Genome Atlas, we reveal disparities in molecular properties between the left and right colon affecting many genes. Interestingly, alterations in genes responsive to environmental cues and properties of the tumour ecosystem, including metabolites which we quantify in a cohort of 27 colorectal cancer patients, exhibit continuous trends along the colon. Employing network methodologies, we uncover close interactions between metabolites and genes, including drivers of colon cancer, showing continuous abundance or alteration profiles. This underscores how anatomic biases in the composition and interactions within the tumour ecosystem help explaining gradients of carcinogenesis along the colon.

Role of the intestinal microbiota and diet in the onset and progression of colorectal and breast cancers and the interconnection between both types of tumours

Colorectal cancer (CRC) is among the leading causes of mortality in adults of both sexes worldwide, while breast cancer (BC) is among the leading causes of death in women. In addition to age, gender, and genetic predisposition, environmental and lifestyle factors exert a strong influence. Global diet, including alcohol consumption, is one of the most important modifiable factors affecting the risk of CRC and BC. Western dietary patterns promoting high intakes of xenobiotics from food processing and ethanol have been associated with increased cancer risk, whereas the Mediterranean diet, generally leading to a higher intake of polyphenols and fibre, has been associated with a protective effect. Gut dysbiosis is a common feature in CRC, where the usual microbiota is progressively replaced by opportunistic pathogens and the gut metabolome is altered. The relationship between microbiota and BC has been less studied. The estrobolome is the collection of genes from intestinal bacteria that can metabolize oestrogens. In a dysbiosis condition, microbial deconjugating enzymes can reactivate conjugated-deactivated oestrogens, increasing the risk of BC. In contrast, intestinal microorganisms can increase the biological activity and bioavailability of dietary phytochemicals through diverse microbial metabolic transformations, potentiating their anticancer activity. Members of the intestinal microbiota can increase the toxicity of xenobiotics through metabolic transformations. However, most of the microorganisms involved in diet-microbiota interactions remain poorly characterized. Here, we provide an overview of the associations between microbiota and diet in BC and CRC, considering the diverse types and heterogeneity of these cancers and their relationship between them and with gut microbiota.

Dynamic Co-Evolution of Cancer Cells and Cancer-Associated Fibroblasts: Role in Right- and Left-Sided Colon Cancer Progression and Its Clinical Relevance

Simple Summary

The versatile crosstalk between cancer cells and cancer-associated fibroblasts (CAFs) of the tumour microenvironment (TME) drives colorectal carcinogenesis and heterogeneity. Colorectal cancer (CRC) can be classified by the anatomical sites from which the cancer arises, either from the right or left colon. Although the cancer cell–CAF interaction is being widely studied, its role in the progression of cancer in the right and left colon and cancer heterogeneity are still yet to be elucidated. Further insight into the complex interaction between different cellular components in the cancer niche, their evolutionary process and their influence on cancer progression would propel the discovery of effective targeted CRC therapy.

Abstract

Cancer is a result of a dynamic evolutionary process. It is composed of cancer cells and the tumour microenvironment (TME). One of the major cellular constituents of TME, cancer-associated fibroblasts (CAFs) are known to interact with cancer cells and promote colorectal carcinogenesis. The accumulation of these activated fibroblasts is linked to poor diagnosis in colorectal cancer (CRC) patients and recurrence of the disease. However, the interplay between cancer cells and CAFs is yet to be described, especially in relation to the sidedness of colorectal carcinogenesis. CRC, which is the third most commonly diagnosed cancer globally, can be classified according to the anatomical region from which they originate: left-sided (LCRC) and right-sided CRC (RCR). Both cancers differ in many aspects, including in histology, evolution, and molecular signatures. Despite occurring at lower frequency, RCRC is often associated with worse diagnosis compared to LCRC. The differences in molecular profiles between RCRC and LCRC also influence the mode of treatment that can be used to specifically target these cancer entities. A better understanding of the cancer cell–CAF interplay and its association with RCRC and LRCR progression will provide better insight into potential translational aspects of targeted treatment for CRC.

DNA Methylation Biomarkers in Colorectal Cancer: Clinical Applications for Precision Medicine

Colorectal cancer (CRC) is the second leading cause of cancer death worldwide that is attributed to gradual long-term accumulation of both genetic and epigenetic changes. To reduce the mortality rate of CRC and to improve treatment efficacy, it will be important to develop accurate noninvasive diagnostic tests for screening, acute, and personalized diagnosis. Epigenetic changes such as DNA methylation play an important role in the development and progression of CRC. Over the last decade, a panel of DNA methylation markers has been reported showing a high accuracy and reproducibility in various semi-invasive or noninvasive biosamples. Research to obtain comprehensive panels of markers allowing a highly sensitive and differentiating diagnosis of CRC is ongoing. Moreover, the epigenetic alterations for cancer therapy, as a precision medicine strategy will increase their therapeutic potential over time. Here, we discuss the current state of DNA methylation-based biomarkers and their impact on CRC diagnosis. We emphasize the need to further identify and stratify methylation-biomarkers and to develop robust and effective detection methods that are applicable for a routine clinical setting of CRC diagnostics particularly at the early stage of the disease.

Can dietary flavonoids be useful in the personalized treatment of colorectal cancer?

Activating mutations in the oncogenes KRAS, BRAF and PI3K define molecular colorectal cancer (CRC) subtypes because they play key roles in promoting CRC development and in determining the efficacy of chemotherapeutic agents such as 5-fluorouracil and anti-epidermal growth factor receptor monoclonal antibodies. Survival of patients with cancers displaying these molecular profiles is low. Given the limited efficacy of therapeutic strategies for CRC presenting mutational activations in mitogen-activated protein kinase and/or PI3K pathways, developing combination therapies with natural flavonoids or other phytochemicals with demonstrated effects on these pathways (and little or no toxic effects) may constitute a valuable path forward. Much has been published on the anticancer effects of dietary phytochemicals. However, even an exhaustive characterization of potential beneficial effects produced by in vitro studies cannot be extrapolated to effects in humans. So far, the available data constitute a good starting point. Published results show quercetin and curcumin as possibly the best candidates to be further explored in the context of adjuvant CRC therapy either as part of dietary prescriptions or as purified compounds in combination regimens with the drugs currently used in CRC treatment. Clinical trial data is still largely missing and is urgently needed to verify relevant effects and for the development of more personalized treatment approaches.

Colorectal microbiota after removal of colorectal cancer

The colonic microbiome has been implicated in the pathogenesis of colorectal cancer (CRC) and intestinal microbiome alterations are not confined to the tumour. Since data on whether the microbiome normalises or remains altered after resection of CRC are conflicting, we studied the colonic microbiota of patients after resection of CRC. We profiled the microbiota using 16S rRNA gene amplicon sequencing in colonic biopsies from patients after resection of CRC (n = 63) in comparison with controls (n = 52), subjects with newly diagnosed CRC (n = 93) and polyps (i = 28). The colonic microbiota after surgical resection remained significantly different from that of controls in 65% of patients. Genus-level profiling and beta-diversity confirmed two distinct groups of patients after resection of CRC: one with an abnormal microbiota similar to that of patients with newly diagnosed CRC and another similar to non-CRC controls. Consumption levels of several dietary ingredients and cardiovascular drugs co-varied with differences in microbiota composition suggesting lifestyle factors may modulate differential microbiome trajectories after surgical resection. This study supports investigation of the colonic microbiota as a marker of risk for development of CRC.

Association between severity of COVID-19 symptoms and habitual food intake in adult outpatients

Objective

To evaluate the association between habitual frequency of food intake of certain food groups during the COVID-19 pandemic and manifestations of COVID-19 symptoms in adult outpatients with suspected SARS-CoV-2 infection.

Design

We included 236 patients who attended an outpatient clinic for suspected COVID-19 evaluation. Severity of symptoms, habitual food intake frequency, demographics and Bristol chart scores were obtained before diagnostic confirmation with real-time reverse transcriptase PCR using nasopharyngeal swab.

Results

The results of the COVID-19 diagnostic tests were positive for 103 patients (44%) and negative for 133 patients (56%). In the SARS-CoV-2-positive group, symptom severity scores had significant negative correlations with habitual intake frequency of specific food groups. Multivariate binary logistic regression analysis adjusted for age, sex and occupation confirmed that SARS-CoV-2-positive patients showed a significant negative association between having higher symptom severity and the habitual intake frequency of ‘legumes’ and ‘grains, bread and cereals’.

Conclusions

Increase in habitual frequency of intake of ‘legumes’, and ‘grains, bread and cereals’ food groups decreased overall symptom severity in patients with COVID-19. This study provides a framework for designing a protective diet during the COVID-19 pandemic and also establishes a hypothesis of using a diet-based intervention in the management of SARS-CoV-2 infection, which may be explored in future studies.

The Changing Landscape of Legume Products Available in Australian Supermarkets

Evidence supports regular dietary inclusion of legumes due to their positive effects on both human and planetary health. Intake within Australia is suboptimal, with consumer data suggesting that an inability to integrate legumes into usual dietary patterns is a barrier to consumption. This places the food industry in a unique position to offer Australians the ability to incorporate legumes into usual dietary patterns via innovative new products. The aim of this study was to explore the legume category and compare nutrition product data and the use of nutrition and health claims between 2019 and 2021. An audit of legume products from four major metropolitan Sydney supermarkets (Aldi, Coles, IGA, Woolworths) collected ingredient lists, nutrition information and on-pack claims for baked beans, legume dips, legume flours, legume snacks (including subcategories of legume chips and whole legume snacks), canned legumes, dried legumes, frozen legumes, and pulse pasta. The total number of legume products available on the market nearly doubled from 2019 (n = 312) to 2021 (n = 610); this was driven by traditional plain canned and dried legumes and some new and convenient options, particularly snacks (legume chips) where the largest growth occurred. Of all legume products (n = 610), 82% met the Nutrient Profiling Scoring Criteria, 86.8% were at least a source of dietary fibre, and 55.9% were at least a source of protein. Nutrition content claims relating to dietary fibre, gluten free and protein more than doubled since 2019, with each featuring on over one third of the products identified in 2021. Vegan/vegetarian on-pack claims more than doubled since 2019, and claims related to the term plant-based/plant protein and environmental sustainability emerged on packs in 2021. By addressing barriers to consumption, such as lack of time and knowledge on how to prepare legumes, innovative legume products may help influence future consumption patterns.

Escherichia coli and colorectal cancer: Unfolding the enigmatic relationship

Colorectal cancer (CRC) is one of the deadliest cancers in the world. Specific strains of intestinal Escherichia coli (E. coli) may influence the initiation and development of CRC by exploiting virulence factors and inflammatory pathways. Mucosa-associated E. coli strains are more prevalent in CRC biopsies in comparison to healthy controls. Moreover, these strains can survive and replicate within macrophages and induce a pro-inflammatory response. Chronic exposure to inflammatory mediators can lead to increased cell proliferation and cancer. Production of colobactin toxin by the majority of mucosa-associated E. coli isolated from CRC patients is another notable finding. Colibactin-producing E. coli strains, in particular, induce double-strand DNA breaks, stop the cell cycle, involve in chromosomal rearrangements of mammalian cells and are implicated in carcinogenic effects in animal models. Moreover, some enteropathogenic E. coli (EPEC) strains are able to survive and replicate in colon cells as chronic intracellular pathogens and may promote susceptibility to CRC by downregulation of DNA Mismatch Repair (MMR) proteins. In this review, we discuss current evidence and focus on the mechanisms by which E. coli can influence the development of CRC.

Inclusion of limited amounts of extruded legumes plus cereal mixes in normocaloric or obesogenic diets for rats: effects on intestinal microbiota composition

BACKGROUND

Differences in the composition of the intestinal microbiota and energetic metabolism between lean and obese populations have been described. Legume consumption has been reported to modulate intestinal microbiota composition. However, to the best of our knowledge, no information can be found in the literature on the effects of consumption of diets containing extruded legume plus cereal mixes on the intestinal microbiota composition of rats. Our purpose was to evaluate the effects on lipids profile (see the accompanying paper) and intestinal microbiota composition (current paper) of incorporating this new food ingredient in normocaloric and obesogenic diets.

RESULTS

Intestinal and fecal qPCR-based microbial composition of rats fed the extruded legumes plus cereal mixes differed (P < 0.05) from controls. Obesogenic diets did not affect bacterial counts. However, the inclusion of the extruded mixes reduced (P < 0.05) log₁₀ counts in some bacterial groups and increased (P < 0.05) counts of Lactobacilli, while others remained unaffected. PCoA at the genus level grouped together Lactobacillus reuteri, Akkermansia miciniphila and species from Parabacteroides, Prevotella, Rikenellaceae, and Lactobacillus with extruded legume plus cereal diets. Feeding on extruded legumes plus cereal mixes was associated with increased mRNA expression of the cytokines IL6 and TNF-α and decreased expression of TLR4.

CONCLUSIONS

Our results show that the inclusion in the feed of limited amounts of extruded legumes plus cereal mix, providing a diet that is closer to a normal human one, did modulate the intestinal microbiota composition. Taken together, these results point to the protective, health-promoting properties of extruded legume plus cereal mixes.

Selection of Wild Lactic Acid Bacteria Strains as Promoters of Postbiotics in Gluten-Free Sourdoughs

The occurrence of inflammatory responses in humans is frequently associated with food intolerances and is likely to give rise to irritable bowel disease. The use of conventional or unconventional flours to produce gluten-free baking doughs brings important technological and nutritional challenges, and the use of the sourdough biotechnology has the potential to overcome such limitations. In addition, the typical metabolic transformations carried out by Lactic Acid Bacteria (LAB) can become an important biotechnological process for the nutritional fortification and functionalization of sourdoughs due to the resulting postbiotics. In such a context, this research work aimed at isolating and selecting new LAB strains that resort to a wide range of natural environments and food matrices to be ultimately employed as starter cultures in gluten-free sourdough fermentations. Nineteen LAB strains belonging to the genera of Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus were isolated, and the selection criteria encompassed their acidification capacity in fermentations carried out on chickpea, quinoa, and buckwheat flour extracts; the capacity to produce exopolysaccharides (EPS); and the antimicrobial activity against food spoilage molds and bacteria. Moreover, the stability of the LAB metabolites after the fermentation of the gluten-free flour extracts submitted to thermal and acidic treatments was also assessed.