The tumor mycobiome: A paradigm shift in cancer pathogenesis

Abstract

Distinct fungal communities or "mycobiomes" have been found in individual tumor types and are known to contribute to carcinogenesis. Two new studies present a comprehensive picture of the tumor-associated mycobiomes from a variety of human cancers. These studies reveal that fungi, although in low abundance, are ubiquitous across all major human cancers and that specific mycobiome types can be predictive of survival.

Figure 1.. Distinct mycobiome signature and immune response in different cancers

(A) Fungal diversity in WIS and TCGA cohorts. Fungi belonging to classes Malasseziomycetes, Saccharomycetes, Diothideomycetes, Sordariomycetes, and the genus Candida were found to be significantly enriched in various types of cancers while some specific fungi were only found in a cancer at a specific site. (B) Potential effects of fungi in tumors on mycobiome-bacteriome-immunome interactions. Gene regulation in various cancers in response to high abundance of Candida. The upregulation of pro-inflammatory cytokines, especially interleukin 6 (IL-6), is well known to promote cancer progression. At the same time, chronic inflammation also promotes Candida growth, suggesting that Candida infection in various cancers may be key to cancer therapy. Fungal-driven, pan-cancer “mycotypes” with distinct immune responses can predict survival. Narunsky-Haziza et al. proposed three distinct fungal based fungi-bacteria-immune clusters called “mycotypes”: F1 (Malassezia-Ramularia-Trichosporon), F2 (Aspergillus-Candida), and F3 (multi-genera including Yarrowia). The log-ratio comparisons of these myotypes and clinical data may have the potential to predict cancer survival.