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. 2021 Jun 14;13(7):e08253. doi: 10.15252/emmm.201708253

Figure 3. Differential roles of Ang1 and Ang2 in established growing tumors vs. metastatic dissemination.

Figure 3

(A) At the site of established growing tumors, Ang2 acts as an angiogenesis initiator, while exogenous Ang1 diminishes the anti‐tumor efficacy of anti‐angiogenic anti‐VEGF and anti‐Ang2 therapies (Falcón et al, 2009; Huang et al, 2009; Coxon et al, 2010; Daly et al, 2013). (B) At the destination sites of metastasis, Ang2 de‐stabilizes the "normal" host blood vessels to facilitate various steps in the metastatic cascade (Talmadge & Fidler, 2010). (1) Tumor cell adhesion to capillary wall (Kim et al, 2001); (2) tumor cell extravasation (Gavard et al, 2008); and (3) tumor cell co‐option of existing host vessels (Holash et al, 1999). We thus hypothesize that Ang1, a vascular stabilizing factor, may inhibit these early metastatic events, i.e., in the lung: (1') inhibition of cancer cell adhesion and arrest (Michael et al, 2017); and (2') inhibition of extravasation due to stabilized vessels (Wu et al, 2015).