The potential mechanism of Neu5Gc inducing colorectal cancer based on network pharmacology and experimental validation

Dietary intake of the red meat-derived glycan Neu5Gc fuels colorectal cancer through up-regulation of Wnt signaling pathway

Colorectal cancer (CRC) is a significant health concern, often linked to western diets, particularly red meat consumption. Several mechanisms, such as the high heme iron content, the formation of N-nitroso compounds (NOCs), heterocyclic amines (HCAs), and polycyclic aromatic hydrocarbons (PAHs), have been suggested to explain red meat's cancer-promoting effects. However, these factors are also found in fish and poultry, which are not linked to CRC risk. A new hypothesis attributes red meat's impact on CRC to its high content of a nonhuman glycan. While most mammals express N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), humans express only Neu5Ac due to the loss of the CMAH enzyme. A red meat-rich diet leads to the incorporation of Neu5Gc into human cells, triggering an antibody-mediated inflammatory process known as xenosialitis. This study shows that Neu5Gc incorporation into CRC cells activates the Wnt/β-catenin signaling pathway, promoting cell proliferation. In a murine model lacking CMAH, a Neu5Gc-enriched diet induced intestinal polyp growth, with more malignant characteristics. Additionally, Neu5Gc incorporation in intestinal cells increased the expression of genes downstream of Wnt signaling. These findings reveal, for the first time in an in vivo model, a mechanism independent of immune response, where red meat consumption accelerates tumor progression through Neu5Gc incorporation. This activation of the Wnt/β-catenin signaling pathway provides new insight into how red meat consumption may influence CRC progression.

The Role of Non-Human Sialic Acid Neu5Gc-Containing Glycoconjugates in Human Tumors: A Review of Clinical and Experimental Evidence

N-Glycolylneuraminic acid (Neu5Gc) is a sialic acid variant commonly found in most mammals but not synthesized by humans due to an inactivating mutation in the CMP-Neu5Ac hydroxylase (CMAH) gene. Despite this, Neu5Gc-containing molecules are consistently detected in human tissues, particularly in malignant tumors. However, the mechanisms underlying Neu5Gc accumulation and its role in cancer development remain poorly understood.

OBJECTIVES

This review aims to analyze clinical and experimental evidence regarding the presence of Neu5Gc-containing glycoconjugates in both tumor and non-tumor human tissues, exploring potential mechanisms of the Neu5Gc expression and evaluating its contribution to tumor biology, with a particular focus on the Neu5Gc-GM3 ganglioside.

METHODS

A comprehensive review of the literature was conducted, integrating findings from immunohistochemistry, chromatography, and molecular studies to assess the expression and implications of Neu5Gc in cancer biology.

RESULTS

Neu5Gc-containing glycoconjugates were found to preferentially accumulate in various malignant tumors, while their presence in normal tissues was restricted to cells with high turnover rates. This accumulation is potentially mediated by dietary uptake, hypoxic conditions, and metabolic alterations in cancer cells. Additionally, Neu5Gc-containing molecules were associated with the activation of oncogenic pathways.

CONCLUSION

Neu5Gc-containing glycoconjugates play a multifaceted role in cancer progression and present potential as prognostic markers and therapeutic targets.

Variability of Sialic Acids in Beef Breeds and Nutritional Implications in Red Meat

This study examines the variability of sialic acids, specifically N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), in beef from seven cattle breeds (Holstein Friesian, Red Pied, Maremmana, Chianina, Charolais, Limousin, and Piemontese). Neu5Gc, a non-human sialic acid linked to inflammation and disease risk, showed significant breed differences (p < 0.001), with the highest concentration in Holstein Friesian (61.02 µg/g) and the lowest in Piemontese (20.87 µg/g). Neu5Ac, known for its neuroprotective properties, was most abundant in Piemontese (112.99 µg/g, p = 0.032) and lowest in Limousin (81.25 µg/g). The Neu5Ac/Neu5Gc ratio, critical for dietary health, exceeded the threshold of 5:1 only in Piemontese (5.49), identifying it as a breed with a higher ratio. This study highlights the influence of breed, with limited effects of muscle type and aging, on sialic acid content. Significant correlations were observed between Neu5Gc and fatty acid classes (p < 0.05) and between Neu5Ac and polar amino acid groups (p < 0.01). The findings support selective breeding to optimize beef's nutritional profile, enhancing its health benefits for consumers.

Network pharmacology and transcriptomics reveal androgen receptor as a potential protein target for 6PPD-quinone

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-quinone, or 6PPD-Q) has received increasing attention as an emerging hotspot contaminant. The occurrence of 6PPD-Q in dust and fine atmospheric particles indicates substantial human exposure to this toxicant but the hazards of 6PPD-Q to human health is unknown. We used in silico approaches to identify potential human protein targets of 6PPD-Q and conducted preliminary validation through an in vitro cell proliferation assay and an in vivo transcriptomic analysis of prostate tissues from 6PPD-Q-treated mice. Receptor-based reverse screening and network pharmacology identified four hub targets of 6PPD-Q that were closely related to prostate carcinogenesis. Among these four targets, 6PPD-Q exhibited a strong binding tendency to androgen receptor (AR) with a binding free energy of -23.04 kcal/mol. A support vector machine (SVM) model for predicting chemicals with AR agonism or AR-inactivity was established with good prediction performance (mean prediction accuracy: 0.92). SVM prediction and AR-mediated cell-based assays, with a known AR agonist and a proposed AR inactive agent as positive and negative controls, confirmed that 6PPD-Q displayed AR agonism. Upregulation of Ar mRNA expression (FC = 1.29, p = 0.0404) and its related prostate cancer pathway was observed in the prostate of mice exposed to environmentally realistic concentrations of 6PPD-Q, suggesting a potential role in promoting prostate carcinogenesis. These findings provide evidence that 6PPD-Q agonized AR to exert downstream gene transactivation and imply its prostate cancer risks to humans.

Huangqi-Guizhi-Wuwutang protects against oligospermia in mice by promoting the proliferation of spermatogenic stem cells: A comprehensive study using HPLC-Q-TOF/MS and experimental pharmacology

The classical traditional Chinese medicine formula Huangqi-Guizhi-Wuwutang (HGW) has been shown to enhance sperm production. However, the bioactive components and comprehensive mechanisms underlying the therapeutic effects remain unclear. The present study investigates the potential active ingredients and underlying mechanisms of HGW against spermatogenesis dysfunction. The chemical components of HGW were analyzed by mass spectrometry. And then the "components-targets-pathway-disease" network was constructed using network pharmacology research methods, which aimed to identify the key active components and potential targets of HGW in treating oligospermia. Experimental validation was finally conducted in animal model. The male-specific pathogen-free Kunming mice were divided into five groups: Sham group, Model group, and HGW groups (8, 16, and 32 g/kg of HGW by gavage for 35 days). Chemical profile and network pharmacology results revealed that potential bioactive compounds were dihydrocinnacasside, isomucronulatol, and 6-gingerol, and the mechanism of which was enriched in regulating spermatogenic stem cells (SSCs), endocrine function, and apoptosis. The administration of HGW significantly improved oligospermia in mice. HGW significantly upregulated the expression of marker proteins in SSCs and the potential targets within the testis simultaneously. Our data indicates that HGW enhances the proliferation of SSCs, and HGW can be a promising therapeutic candidate for oligospermia.

Association of saturated fatty acids with cancer risk: a systematic review and meta-analysis

OBJECTIVE

Extensive research has explored the link between saturated fatty acids (SFAs) and cardiovascular diseases, alongside other biological dysfunctions. Yet, their association with cancer risk remains a topic of debate among scholars. The present study aimed to elucidate this association through a robust meta-analysis.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science databases were searched systematically to identify relevant studies published until December 2023. The Newcastle-Ottawa Scale was used as the primary metric for evaluating the quality of the included studies. Further, fixed- or random-effects models were adopted to determine the ORs and the associated confidence intervals using the Stata15.1 software. The subsequent subgroup analysis revealed the source of detection and the cancer types, accompanied by sensitivity analyses and publication bias evaluations.

RESULTS

The meta-analysis incorporated 55 studies, comprising 38 case-control studies and 17 cohort studies. It revealed a significant positive correlation between elevated levels of total SFAs and the cancer risk (OR of 1.294; 95% CI: 1.182-1.416; P-value less than 0.001). Moreover, elevated levels of C14:0, C16:0, and C18:0 were implicated in the augmentation of the risk of cancer. However, no statistically significant correlation of the risk of cancer was observed with the elevated levels of C4:0, C6:0, C8:0, C10:0, C12:0, C15:0, C17:0, C20:0, C22:0, and C24:0. Subgroup analysis showed a significant relationship between excessive dietary SFA intake, elevated blood SFA levels, and heightened cancer risk. Increased total SFA levels correlated with higher risks of breast, prostate, and colorectal cancers, but not with lung, pancreatic, ovarian, or stomach cancers.

CONCLUSION

High total SFA levels were correlated with an increased cancer risk, particularly affecting breast, prostate, and colorectal cancers. Higher levels of specific SFA subtypes (C14:0, C16:0, and C18:0) are also linked to an increased cancer risk. The findings of the present study would assist in providing dietary recommendations for cancer prevention, thereby contributing to the development of potential strategies for clinical trials in which diet-related interventions would be used in combination with immunotherapy to alter the levels of SFAs in patients and thereby improve the outcomes in cancer patients. Nonetheless, further high-quality studies are warranted to confirm these associations.