Abstract

Caveolin-1 (CAV1) expression in B16F10 melanomas enhances migration and invasiveness in vitro and promotes lung metastasis in vivo. However, it remains unclear which steps are modulated by CAV1 during metastasis. The lack of information is due to the inability to track these cells real time once injected into the animals. Here we used nanoparticles to label cells as a means to permit tracking in our animal model. B16F10 cells transfected (pLacIOP-CAV1,pLacIOP) were labeled with gold nanoparticles (GNPs-12nm) conjugated cell penetrating peptides (CR7,Cys-TAT(48-60),R(7)CLPFFD) labeled with Alexa647. Viability (MTS), migration (transwell), invasiveness (Matrigel) and internalization (confocal microscopy) were evaluated. Labeled cells were injected into the tail vein of C57BL/6 mice and fluorescence and gold levels in the lung were determined within 24h ex vivo. Finally, labeled cells were detected by optical microscopy in lung slices after gold enhancement staining. Conjugated GNPs were incorporated into B16F10 cells without affecting viability, migration, invasiveness and metastasis, suggesting that GNP-labeled cells could be used for tracking in vivo. Indeed, both fluorescence and gold were detectable ex vivo in lungs. 1h post-injection suggests that initial adhesion to lung capillaries is similar for both cell types. However, colonization after 24h was more effective for CAV1 expressing cells, possibly due to more persistent adhesion required for transendothelial migration.