Compromised Blood-Brain Barrier Junctions Enhance Melanoma Cell Intercalation and Extravasation

Area of Science:

• Oncology
• Neuroscience
• Cell Biology

Background:

• Melanoma frequently metastasizes to the brain, posing a significant clinical challenge.
• Understanding melanoma cell extravasation across the blood-brain barrier (BBB) is crucial for preventing brain metastasis.

Purpose of the Study:

• To investigate the molecular and cellular mechanisms of melanoma cell extravasation across the BBB.
• To identify factors influencing melanoma cell interaction with and penetration of the BBB.

Main Methods:

• Utilized primary mouse brain microvascular endothelial cells (pMBMECs) as an in vitro BBB model.
• Imaged melanoma cell interactions with pMBMEC monolayers.
• Employed Interleukin (IL)-1β stimulated and PECAM-1-knockout pMBMECs to model compromised BBB.
• Used a brain-homing melanoma cell line (YUMM1.1-BrM4) and PECAM-1-deficient mice for in vivo studies.

Main Results:

• Observed exclusive junctional intercalation of melanoma cells into endothelial monolayers.
• Demonstrated that melanoma-induced pMBMEC barrier disruption can be rescued by protease inhibition.
• Showed increased melanoma cell intercalation in compromised BBB models (IL-1β stimulated or PECAM-1-knockout pMBMECs).
• Confirmed increased in vivo melanoma cell extravasation across the BBB in barrier-compromised PECAM-1-deficient mice.

Conclusions:

• Preserving blood-brain barrier integrity is a critical measure to limit melanoma brain metastasis.
• Melanoma cell extravasation is influenced by BBB integrity and specific molecular interactions.