Angers University: Fungal dysbiosis and gastric tumorigenesis

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Angers University: Fungal dysbiosis and gastric tumorigenesis

Angers University: Fungal dysbiosis and gastric tumorigenesis.  The gastrointestinal tract contains a huge and diverse microbial reservoir, composed of bacteria, fungi and viruses, which have a positive contribution to human health.

There is increasing evidence that interference with normal microflora can promote a variety of human disease states including tumorigenesis. Whether the fungal components of the intestinal microflora (i.e. fungal flora) affect the development of tumors has not been studied in detail.

In the latest issue of Theranostics, Zhong et al. (2021) clarified the relationship between mycobacterial flora imbalance and gastric cancer. These findings indicate that the fungal flora is related to the occurrence of gastric cancer, and lay the foundation for future mechanism research to explore whether the fungal biological disorder is the cause or consequence of gastric cancer, which is of great significance to preventive strategies.

Image source: doi: 10.7150/thno.61480

Cancer is still the second leading cause of death in the world after heart disease. Although lung cancer has claimed the most lives in the world, gastric cancer (GC) ranks fourth, with more than 1 million new cases worldwide and 600,000 to 700,000 deaths every year.

More and more evidences show that the microflora plays an important role in influencing the carcinogenesis of the gastrointestinal tract, especially the bacterial components that can prevent or promote tumorigenesis.

For example, Helicobacter pylori has long been associated with the development of peptic ulcer disease. It is a carcinogen that increases the risk of stomach cancer.

Although recent studies have shown that intestinal fungi are related to the occurrence of pancreatic, esophageal and colon tumors, little is known about the importance of fungi in the development of gastrointestinal tumors.

In this issue of Theranostics, Zhong and his colleagues reported on the link between fungal flora imbalance and GC.

In this study, Song Yongxi and Hong Xuehui’s research team took advantage of surgical biopsy, including cancerous lesions and adjacent non-cancerous tissues, from 45 patients admitted to the First Affiliated Hospital of China Medical University in Shenyang, China.

The authors used non-culture-based high-throughput amplified sequences to characterize fungal populations in disease and healthy tissues.

First, their results indicate that the Ascomycota and Basidiomycota are the most abundant fungal phyla in GC and control samples, and to a lesser extent. In fact, these two dominant taxa accounted for more than 90% of the fungi in all samples.

This finding is consistent with the diversity of fungi present in the human environment, and may reflect the fact that the components of the fungal community in the stomach tissue come from continuous intake and inhalation of saprophytic yeast and mold.

The author further believes that the imbalance of gastric fungus is related to gastric cancer, because principal component analysis shows that gastric cancer and the control group clustered separately. Compared with non-cancer control samples, Candida and Alternaria were significantly increased in GC tissue samples, while other genera such as Saitozyma (Protocryptococcus) and Thermomyces (Thermus) in cancer tissues Medium is less.

Interestingly, further statistical analysis aimed at determining GC fungal indicators showed that the observed fungal dysregulation was mainly due to a single yeast, Candida albicans, which is usually a commensal species in the human intestine.

The global diversity of gastric fungal flora observed in the control samples may be due to the substantial increase in the composition of this normal microflora. Further experiments, such as culture methods using GC samples, need to verify the increase in the burden of Candida albicans.

In fact, many of the fungal genera commonly found in the human environment, therefore inhaled or ingested every day, are not so abundant in GC samples. This raises an important question, that is, whether Candida albicans mediates GC by reducing the diversity and abundance of fungi in the stomach, or is it directly involved in the pathogenesis of GC.

Finally, Zhong and his colleagues provided reliable statistical analysis, showing that Candida albicans has a significant effect in distinguishing between GC and control samples, so it can be used as a potential biomarker for disease tissues.

Mycobacterial dysbiosis: a new link in the development of gastric tumors

Image source: doi: 10.7150/thno.61480

In summary, the research team provided evidence that the characteristics of the fungal ecosystem in gastric tissue may help distinguish gastric cancer from non-cancerous lesions, although Candida albicans and other reported species that indicate whether it is found to be the result of gastric cancer or as a result One of the many factors that cause gastric cancer is still an open question.

Recent progress has shown that, in a specific pathophysiological context, the microbial populations associated with gastrointestinal tissues or mucous membranes cannot be well reflected in paired stool samples.

This new paradigm not only highlights the potential importance of fungi in the pathogenesis of certain cancers, but may also provide a theoretical basis for the development of diagnosis, prevention and treatment strategies.

(source:internet, reference only)

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