Melanoma is the most aggressive
skin cancer in humans. One severe complication is the formation of brain
metastasis, which requires extravasation of
melanoma cells across the tight blood-brain barrier (BBB). Previously,
VLA-4 has been assigned a role for the adhesive interaction of
melanoma cells with non-BBB endothelial cells. However, the role of
melanoma VLA-4 for breaching the BBB remained unknown. In this study, we used a mouse in vitro BBB model and imaged the shear resistant arrest of
melanoma cells on the BBB. Similar to effector T cells, inflammatory conditions of the BBB increased the arrest of
melanoma cells followed by a unique post-arrest behavior lacking immediate crawling. However, over time,
melanoma cells intercalated into the BBB and compromised its barrier properties. Most importantly, antibody ablation of
VLA-4 abrogated
melanoma shear resistant arrest on and intercalation into the BBB and protected the BBB from barrier breakdown. A tissue microarray established from human brain
metastasis revealed that indeed a majority of 92% of all human
melanoma brain metastases stained
VLA-4 positive. We propose
VLA-4 as a target for the inhibition of brain
metastasis formation in the context of
personalized medicine identifying metastasizing
VLA-4 positive
melanoma.