Apatinib attenuates CRKII-Mediated angiogenesis: Possible implications for metastasis prevention from small extracellular vesicle proteomics.

High postoperative recurrence severely compromises treatment for triple-negative breast cancer (TNBC) surgical outcomes. We investigated Apatinib's potential as an adjuvant therapy targeting sEV (Small Extracellular Vesicle)-mediated angiogenesis within the tumor microenvironment to identify novel prognostic biomarkers. We employed quantitative label-free proteomics to screen for key therapeutic targets in TNBC-derived sEVs. The anti-angiogenic efficacy and potential anti-metastatic activityof Apatinib was evaluated using in vitro functional assays (proliferation, migration, adhesion, invasion, and tube formation) and an in vivo TNBC syngeneic mouse model. To validate its translational potential, we analyzed the regulation of the CRKII-PXN/VEGFA axis and its correlation with tumor angiogenesis and growth inhibition. Proteomic analysis identified the adaptor protein CRKII as a central hub significantly downregulated by Apatinib in sEVs. Mechanistically, Apatinib disrupted the transmission of pro-angiogenic signals to endothelial cells by reducing sEV-CRKII (small extracelluar vesicle-CRKII), which subsequently inhibited the downstream CRKII-PXN/VEGFA signaling axis. Functional validation confirmed that CRKII knockdown mimicked, while overexpression reversed, the anti-angiogenic effects of Apatinib. In the preclinical model, Apatinib significantly suppressed tumor growth and reduced microvessel density, suggesting its efficacy in controlling tumor burden and potential micrometastases. Apatinib effectively inhibits TNBC angiogenesis and exhibits potential anti-metastatic activity by downregulating sEV-CRKII and blocking the CRKII-PXN/VEGFA axis. These findings suggest that Apatinib may have potential as a postoperative adjuvant therapy for metastasis prevention. Furthermore, sEV-CRKII emerges as a promising non-invasive biomarker for surgeons to monitor therapeutic response and recurrence risk in TNBC patients.