Mechanisms of the gut-lung axis in regulating lung metastasis of colorectal cancer and advances in traditional Chinese medicine intervention

Figure 2 Mechanisms that we put forward, by which Fusobacterium nucleatum promotes the occurrence of colorectal cancer lung metastasis. A: FadA binds with E-cadherin, which leads to β-catenin release, and then the process of epithelial-mesenchymal transition occurs; B: The activation process of Toll-like receptor 4/MyD88/nuclear factor kappa B can upwardly regulate the expression level of Snail; C: Exosome-derived human circRNA hsa_circ_0004085 may enhance drug resistance and pre-activate lung fibroblasts; D: Succinate has the function of making hypoxia-inducible factor-1 alpha become stabilized. CRC: Colorectal cancer; EMT: Epithelial-mesenchymal transition; TLR4: Toll-like receptor 4; NF-κB: Nuclear factor kappa B; HIF-1α: Hypoxia-inducible factor-1 alpha.