Skip to main content
. 2023 Jul 27;24(1):2240084. doi: 10.1080/15384047.2023.2240084

Figure 2.

Tumor microenvironment with cancer cells (in red), immune cells (in purple and blue), and microbes (in yellow) (middle), from which four arrows point to insets showing metabolite-mediated interactions (top left), direct interactions (bottom left), inflammatory pathways (top right), and barrier disruption (bottom right). Tumor microenvironment with cancer cells (in red), immune cells (in purple and blue), and microbes (in yellow) (middle), from which four arrows point to insets showing metabolite-mediated interactions (top left), direct interactions (bottom left), inflammatory pathways (top right), and barrier disruption (bottom right). Metabolite-mediated interactions (top left) involves the production of small molecules (shown with various shapes) from microbes interacting with host cells through receptors or by diffusion and can be pro-tumorigenic, including DNA repair methods, anti-apoptosis methods, and other signaling methods, or anti-tumorigenic, including reactive oxygen species production, immune cell activation, or DNA damage mechanisms. Direct interactions (bottom left) involve microbes (in purple) directly affecting host cells, mainly by bypassing cellular arrest mechanisms, shown by a microbe interacting with a cellular receptor. Inflammatory pathways (top right) include host immune cells that are activated by microbes or their metabolites (both in brown), allowing these immune cells to directly attack cancer cells by triggering immune cell-mediated apoptosis or phagocytosis. Barrier disruption (bottom right) mainly involves microbes (in purple) disrupting host barriers to allow for microbes and cancer cells to spread through the body to promote metastasis, seen by the gaps in endothelial barriers allowing for microbes and cancer cells to leave their current niche.

As microbes are present in local tissues, the tumor microenvironment (middle), and within tumor cells themselves, these tumor-associated microbes have been found to impact different cancer types through different methods, including metabolite-mediated interactions that can be pro-tumorigenic or anti-tumorigenic (top left); direct interactions with cancer cells to control the cell cycle and proliferation (bottom left); activation of inflammatory cells (glowing cells), such as T-cells (in blue), macrophages (in purple), and antibodies (in blue) (top right); and by disrupting vascular barriers to promote metastasis (bottom right).