[Gut microbiota involved in cancer invasion and metastasis]

The gut microbiota, as the "second genome" of the human body, plays a crucial role in maintaining the host's homeostasis and regulating the disease process. The latest research indicates that intestinal microecological imbalance is an important cause that triggers and accelerates tumor metastasis. The gut microbiota mainly promotes tumor invasion and metastasis through the following 2 mechanisms: 1) Contact-dependent mechanism, specific pathogenic bacteria directly adhere and invade tumor cells through surface proteins, inducing epithelial-mesenchymal transition and cytoskeleton remodeling; 2) non-contact-dependent mechanism, metabolites derived from the microbiota act on distant organs through the bloodstream, activating signaling pathways to construct pre-metastatic ecological niches and inducing systemic immunosuppression. Precise intervention strategies for the gut microbiota include supplementing specific probiotics with anti-cancer potential, selective antibiotics or phage therapy against specific pathogenic bacteria, fecal microbiota transplantation and microbial vaccines. Although preliminary studies have shown promising results, the high heterogeneity of the microbiota, the bidirectional action of metabolites, and the safety of long-term colonization remain bottlenecks for clinical translation. In the future, it is necessary to further clarify the key transfer-promoting microbiota and their characteristic metabolic and signaling mechanisms, promote the development of individualized and precise microbiota intervention strategies, and strengthen clinical translation research, in order to ultimately achieve the goal of effectively preventing and treating tumor metastasis by regulating the gut microbiota.