Table 1.
Mechanism of CTCs participate in cancer metastasis
| Biological process of cancer metastasis |
Characteristics of CTCs | Expression of the related markers on CTCs |
Expression of the factors in tumor microenvironment | Outcomes |
|---|---|---|---|---|
| Intravasation and Angiogenesis | - Motility (active intravasation); - Mobility (passive intravasation); -Epithelial to Mesenchymal plasticity |
EpCAM, CK8/18/19, E-cadherin↓; N-cadherin, Vimentin, Fibronectin↑; Snail, Slug, Zeb, and Twist1↑; N-WASP↑ (Invadopodia formation) |
TGF-β↑ (CAF); VEGF, PDGF↑ (platelet); VEGFA, FGF↑ (macrophage); |
-CTCs undergo EMT and enter into bloodstream; -New vessels formation |
| Survival maintenance | -Anoikis resistance; -Rarity; -Short half-life time; -Single cells or clusters |
CD47, PD-L1, FASL↑; Bcl-2 family, TrkB, FLIB↑; Bax, Bak↓ |
TLRs↓ (macrophage and NK cell); CD41, CD61↑ (platelet) |
-CTCs overcome the shear stress and anoikis; -CTCs escape from the immune surveillance |
| Extravasation and Colonization | -Mesenchymal to Epithelial plasticity; -Homing and dormancy; -Heterogeneity |
EpCAM, CK8/18/19, E-cadherin↑; N-cadherin, Vimentin, Fibronectin↓; TGF-β,VEGF, MUC1, CD44, Integrins, CXCR4, CXCR7↑ |
TGF-β↑ (platelet) E-selectin↑ (endothelial cell); CXCL12↑ (stroma); |
-CTCs undergo MET and leave the bloodstream; -Outgrowth of metastasis or remain dormant |