Table 3.
Correlation between factors that disturb the intestinal flora and breast cancer metastasis and progression.
| Factor | Study model | Regulation | Key biologic function | ||
|---|---|---|---|---|---|
| ETBF | |||||
| BFT | BALB/C, MCF-7, MCF-10A | Up | ETBF produces BFT, which is highly invasive in breast cells and expresses migration- and metastasis-related genes (137–139) | ||
| Antibiotics | |||||
| MMTV-PyMT | Up | Dysbiosis was associated with enhanced distant metastasis and dissemination of breast tumor cells (140) | |||
| BRPKP110 | Up | Infiltration of myeloid cells in breast tissue was enhanced after FMT perfusion (140) | |||
| GFP+ tumor cells | Up | Dysbiosis was associated with increased breast tumor cell dissemination (140) | |||
| M2-like macrophages | Up | Dysbiosis was associated with enhanced infiltration of myeloid cells into the breast tissue (140, 141) | |||
| VNMAA or vancomycin | PyMT-BO1 | Up | Significant reduction in gut microbiota abundance and accelerated tumor growth were observed after VNMAA treatment (146) | ||
| E0771 | Uncertain | Increased homing/value-added of mast cells in breast cancer tumors where gut microbiota were disturbed after antibiotic treatment (146) | |||
| VNMA | PyMT-BO1, E0771 | Up | Antibiotic-induced dysbiosis of microflora was associated with reduced expression of pro-apoptotic genes and increased expression of pro-survival genes (153) | ||
| PyMT-BO1, E0771 | Up | Antibiotic administration was associated with dramatic differences in the regulation of microbial metabolic pathways and increased tumor growth rates in laboratory animals (146, 148) | |||
| cefadroxil | PyMT-BO1 | Up | Gut microbial aggregation, genus differences, and accelerated tumor growth were observed in cefadroxil-treated animals (146, 148) | ||
| Probiotics | |||||
| CRL431 | Down | FM was associated with inhibited mammary tumor growth and metastasis in mice (185) | |||
| Kefir water | 4T1, BALB/C | Down | Administration of kefir water was associated with inhibition of tumor size and distant metastasis with downregulatory effect (190, 191) | ||
| L. brevis | BALB/C | Down | L. brevis administration was associated with immune response and reduced liver metastases from mammary carcinoma in mice (195) | ||
| Microbial metabolite | |||||
| SCFAs | SCFAs | Down | Butyrate has anti-cancer properties (159, 175, 176) | ||
| LCA | MCF-7, SKBR3, 4T1 | Down | LCA was associated with inhibition in the growth of breast cancer cells (180) and reduction in infiltration by the primary tumor into the surrounding tissue and metastasis (168) | ||
| Cadaverine | 4T1, MDA-MB-231, SKBR3 | Down | Cadaverine can fight breast cancer progression by inhibiting EMT, cell motility, chemotaxis, and metastasi (182) | ||
| Diet | |||||
|
Lactobacillus casei Shirota and Soy isoflavones from puberty onwards (207) |
Uncertain | ||||
| polyphenol (173) | Uncertain | ||||
| Fucoidan (209) | Uncertain | ||||
ETBF, Enterotoxigenic Bacteroides fragilis; BFT, B. fragilis; BALB/C, experimental mouse; MCF-7, human breast cancer cells; MCF-10A, epithelial cell line; MMTV-PyMT, mouse model of highly metastatic breast cancer; BRPKP110, HR+ mouse breast cancer cell line model; FMT, fecal microbiota transplantation; GFP+, Green fluorescent protein; VNMAA, vancomycin, neomycin, metronidazole, amphotericin, ampicillin; PyMT-BO1, PyMT-derived ductal cell line in situ mammary fat pad injection model; E0771, spontaneously derived basal cells; VNMA, vancomycin, neomycin, metronidazole, amphotericin; FM, fermented milk; CRL431, type of L. casei used to ferment milk; 4T1, breast cancer cells; SCFAs, short-chain fatty acids; TLR4, Toll-like receptor 4;LCA, lithophanic acid; MDA-MB-231, breast cancer cells; SKBR3, breast cancer cells; EMT, epithelial–mesenchymal transition.