Table 2.
Summary of anti-metastatic microbiome findings.
| Microbiome or Microbial Metabolites |
Cancer Type | Impact on Metastasis * |
Mechanism | In Vivo/In Vitro | Refs. |
|---|---|---|---|---|---|
| Indolepropionic acid (a tryptophan metabolite produced only by intestinal flora) | breast cancer | ↓ | Induces the expression of Vim, FgfBp1, Snail, and β-catenin; and it upregulates the expression of E-cadherin to suppress EMT |
Both | [32] |
| Cadaverine (produced by the intestinal microbiome) | breast cancer | ↓ | Reduces the motility and metastatic nature of cancer stem cells by restoring EMT | Both | [54] |
| Oscillatoria | muscle-invasive bladder cancer (MIBC) | ↓ | Is strongly negatively correlated with EMT-promoting genes | In vitro | [55] |
| Sodium butyrate (a fermentation product of intestinal microorganisms) | CRC | ↓ | Decreases the number of hepatic T regulatory cells and increased the number of NKT cells and Th17 cells | In vivo | [56] |
| Propionic acid and butyric acid (produced by intestinal flora) | melanoma | ↓ | Facilitates the recruitment of Th17 cells to the lung via the CCL20/chemokine receptor 6 axis | In vivo | [57] |
| Lactic acid streptozotocin | Colon cancer | ↓ | Downregulates the serum carcinoembryonic antigen (CEA), CEAM6, MMP-2F, and MMP-9F gene expression | In vitro | [42] |
| Lactobacillus plantarum YYC-3 | Colon cancer | ↓ | Suppresses the VEGF-MMP2/9 signaling pathway | In vitro | [58] |
* ↓ microbes inhibit cancer metastasis.