Molecular Tracking of Proteolysis During Breast Cancer Cell Extravasation: Blockage by Therapeutic Inhibitors
Annual rept. 1 Aug 2002-31 Jul 2003
UNIVERSITY HEALTH NETWORK TORONTO (ONTARIO) GRANT AND CONTRACT SERVICES
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Elucidating the degradive effectors responsible for focal proteolysis at the cell-matrix interface during metastasis is an ongoing challenge. We are dissecting the components of the proteolytic machinery required for breast cancer cells metastatic MDA-MB231 and non-metastatic MCF-7 transendothelial migration and determining the stage of extravasation particularly reliant upon the metalloproteinase activity. Modulation of individual molecules demonstrates the functional cooperation of furin, cell surface adhesion molecules alphavBeta3, CD44, and matrix metalloproteinases MMP-2, MMP-9 and MT1 -MMP during the process of transendothelial migration. Confocal microscopy shows co-localization of molecules critical for MMP cell surface distribution, and disruption of these events and molecules reduces transendothelial migration of MDA-MB231 cells. MMP-2 and MT1 -MMP localization matches the imprint of spatially restricted fluorogenic gelatin digestion. The digestion occurs in a stage-specific manner and becomes most evident during the migratory phase of tumor cell transendothelial migration. Of the above breast cancer cell lines, MDA-MB231 is able to undergo efficient transendothelial migration, and MT1-MMP emerges to be one of the key molecules involved for this event. The lack of several key components in MCF-7 cells impairs its ability to transmigrate. Our data are revealing how specific molecular interactions result in a cooperative proteolytic interface at the tumor cell surface within the breast tumor cell-endothelial cell microenvironment during transendothelial migration, which mimics cancer cell extravasation.
- Medicine and Medical Research