The Effect and Its Mechanism of a Novel Disintegrin GbvIV4 From <scp> <i>Gloydius brevicaudus</i> </scp> Venom on Inhibition Metastasis of Melanoma Cells

Tumor metastasis, a hallmark of advanced cancer, depends on integrin-mediated adhesion and migration. Disintegrins, RGD-containing peptides from snake venom, are potent integrin antagonists with antimetastatic potential. This study characterizes GbvIV4, a novel disintegrin (70 amino acids, RGD motif, MW: 7.44 kDa) isolated from Gloydius brevicaudus venom, and its effects on melanoma progression. GbvIV4 exhibited high affinity for integrins αIIbβ3 (KD = 1.23 μM) and αvβ3 (KD = 650 nM) and inhibited ADP-induced platelet aggregation (IC50 ≈ 1.34 μg/mL). In vitro, GbvIV4 significantly suppressed B16/B16-F10 melanoma cell adhesion, migration, and invasion (~61% inhibition at 4 μg/mL). In vivo, GbvIV4 (3.6 mg/kg, iv) reduced tumor weight by 49.5% (p < 0.05) and impaired angiogenesis, as shown by reduced vessel perfusion using laser speckle contrast imaging. Quantitative proteomics identified ATP/GTP-binding protein-like 2 (AGBL2) as the most downregulated protein in GbvIV4-treated cells, confirmed by RT-PCR and western blot. Collectively, GbvIV4 exerts strong antimetastatic and antiangiogenic effects through dual mechanisms: inhibition of RGD-binding integrins including but not limited to αIIbβ3/αvβ3. GbvIV4 significantly downregulated AGBL2 expression and reduced the level of detyrosinated (glu-) tubulin, indicating inhibition of AGBL2-mediated tubulin detyrosination. These findings suggest GbvIV4 as a promising therapeutic candidate for melanoma treatment and metastasis prevention.