Can Candida cause stomach cancer?

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Abstract​

Candida albicans is an opportunistic pathogenic fungus, which tends to infect the host with defective immune function including cancer patients. A growing number of studies have shown that C. albicansinfection increases the host susceptibility to cancer such as oral, gastric, and colorectal cancer. Cancer and anti-cancer treatment may also affect the colonization of C. albicans. C. albicans may promote the development of cancer by damaging mucosal epithelium, inducing the production of carcinogens, triggering chronic inflammation including Th17 cell-mediated immune response. In this article, we aim to elaborate the interaction between C. albicans and cancers development and summarize the potential molecular mechanisms, so as to provide theoretical basis for prevention, diagnosis and treatment of cancers.

 

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Introduction​

Candida is a group of opportunistic pathogenic fungi, which are often found in the host’s skin, mouth, and gastrointestinal tract. The decrease in the host immunity enhances the risk of Candida infection. Among them, Candida albicans is the most common pathogenic fungus (Mba and Nweze, 2020). In recent years, more and more epidemiological and pathological studies have suggested the significant impact of pathogenic microorganisms on the incidence rates of cancers worldwide (Schottenfeld and Beebe-Dimmer, 2015). However, only some studies have linked fungal infection with cancers. The association between fungal microbiota imbalance and carcinogenesis remains largely unknown. This is due to the relatively low abundance of fungi and the lack of well-defined reference genome (Klimesova et al., 2018; Coker et al., 2019). In addition, the research methods are challenging, so the fungal microbiota is usually explored relatively less than other microorganisms. So far, studies have shown that C. albicans in fungal microorganisms is very closely related to cancer development.

In this article, we aim to review the potential molecular mechanism by which C. albicans promotes cancers progression. This may help clinicians diagnose the early stage of tumor in the future and prescribe a treatment method considering the possible microbial properties in the process of carcinogenesis.

 

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Candida albicans and gastric cancer​

Gastric cancer (GC) is the fifth most common cancer in the world and the third most common cause of cancer-related death (Smyth et al., 2020). After the continuous development of high-throughput sequencing technology, research on the correlation between gastric microbiome (other than Helicobacter pylori) and GC has gradually emerged. A study described the composition and ecological changes of fungi by analyzing the metagenomic sequences in cancer foci and adjacent non-cancer tissues of 45 GC patients. The results showed that GC related fungal biological community was unbalanced, which was characterized by changes in fungal composition and ecology, and suggested that C. albicans might be used as a fungal biomarker of GC. With the significant increase of C. albicans in GC, the abundance of Fusicolla acetilerea, Arcopilus aureus, and Fusicolla aquaeductuum were increased, while Candida glabrata, Aspergillus montevidensis, Saitozyma podzolica, and Penicillium arenicola were obviously decreased (Zhong et al., 2021). In addition, C. albicans reduced the diversity and abundance of fungi in the stomach, thus enhancing the development of GC (Zhong et al., 2021; Table 1). However, these studies did not further clarify the specific molecular mechanism by which C. albicans is involved in the progression of GC.

 

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Conclusion​

At present, most of studies on interaction between C. albicans and cancer are epidemiological survey or descriptive studies. There are few molecular mechanistic studies in this field. Early researchers simply believe that cancer patients are prone to Candida infection. However, tumor is a disease caused by multiple factors. In the mouse model of oral carcinogenesis, a study showed that infection with C. albicans alone could not lead to oral cell dysplasia or OSCC, which requires pretreatment with epithelial carcinogenesis inducer (Dwivedi et al., 2009). C. albicans can promote the occurrence and development of cancer to a certain extent, which may be the result of synergy with the host’s own state and other factors. For example, defective host immunity provides opportunities for C. albicans infection; long-term smoking and drinking provide conditions for C. albicans to produce carcinogenic metabolites; chronic inflammation provides TME and other common factors for C. albicans to promote cancer, and promotes the occurrence and development of cancers.

In conclusion, various adverse factors cause compromised host immunity, leading to C. albicans infection. C. albicans infection increases the risk of cancer development and exacerbates cancer progression. Recent studies have shown that C. albicans infection may participate in the progression of cancer by damaging the epithelial mucosal barrier, producing carcinogenic metabolites, inducing chronic inflammation and Th17 immune response. The progression of cancer further aggravates C. albicans infection. The two promote each other and aggravate the malignant process of cancer development. Therefore, it seems that C. albicans infection may be accompanied by cancer development, and the two promote each other, which in turn aggravates the process of malignancy. It is hoped that these can provide direction for the study of the correlation between C. albicans and cancers, and also provide new ideas for the prevention, diagnosis, and treatment of cancers.

 

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Conclusion​

At present, most of studies on interaction between C. albicans and cancer are epidemiological survey or descriptive studies. There are few molecular mechanistic studies in this field. Early researchers simply believe that cancer patients are prone to Candida infection. However, tumor is a disease caused by multiple factors. In the mouse model of oral carcinogenesis, a study showed that infection with C. albicans alone could not lead to oral cell dysplasia or OSCC, which requires pretreatment with epithelial carcinogenesis inducer (Dwivedi et al., 2009). C. albicans can promote the occurrence and development of cancer to a certain extent, which may be the result of synergy with the host’s own state and other factors. For example, defective host immunity provides opportunities for C. albicans infection; long-term smoking and drinking provide conditions for C. albicans to produce carcinogenic metabolites; chronic inflammation provides TME and other common factors for C. albicans to promote cancer, and promotes the occurrence and development of cancers.

In conclusion, various adverse factors cause compromised host immunity, leading to C. albicans infection. C. albicans infection increases the risk of cancer development and exacerbates cancer progression. Recent studies have shown that C. albicans infection may participate in the progression of cancer by damaging the epithelial mucosal barrier, producing carcinogenic metabolites, inducing chronic inflammation and Th17 immune response. The progression of cancer further aggravates C. albicans infection. The two promote each other and aggravate the malignant process of cancer development. Therefore, it seems that C. albicans infection may be accompanied by cancer development, and the two promote each other, which in turn aggravates the process of malignancy. It is hoped that these can provide direction for the study of the correlation between C. albicans and cancers, and also provide new ideas for the prevention, diagnosis, and treatment of cancers.

Okay bacteria and fungi can cause stomach cancer. And probably parasites and virus too. Everything.

 

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Six things to kill candida.