Role of glycocalyx in breast cancer cell adhesion and transmigration across an in vitro blood-brain barrier (BBB)

Abstract

On the surface of every mammalian cell, there is a matrix-like glycocalyx (GCX) consisting of proteoglycans and glycosaminoglycans (GAGs). Disruption of endothelial cell (EC) GCX by vascular endothelial growth factor (VEGF, VEGF-A165), a tumor secretion, was found to be an early event in tumor cell (TC) metastasis across vascular barriers. But how the TC secretion VEGF affects its own GCX to affect its adhesion and transmigration across EC barriers is unknown. Our recent study by employing Super-resolution Optical Microscopy (STORM) showed that while 1 nM VEGF greatly reduces the length and coverage of heparan sulfate (HS) of GCX at an in vitro BBB formed by human cerebral microvascular endothelial cells (hCMEC), it significantly enhances the coverage of HS on a malignant breast cancer cell, MDA-MB-231 (MB231). In the current study, we want to test the hypothesis that the differential effects of VEGF on the GCX of MB231 and that of the BBB favor MB231 adhesion and transmigration across the BBB for the metastasis. To test this hypothesis, we first generated an in vitro BBB by culturing hCMECs on a Transwell filter with 8 um pores. For adhesion, we added MB231 cells to the BBB under 1) no treatment; 2) after VEGF treatment for MB231 for 2h; 2) after VEGF treatment for the BBB for 2h; and 4) after VEGF treatment for both for 2h. After 1h adhesion, the number of adherent MB231 cells increased by 1.7-fold,1.5-fold and 2.4-fold, respectively for 2), 3) and 4) VEGF treatments, compared to no treatment. For transmigration, we add MB231 cells to the BBB under the same conditions as for adhesion. After 6 h, the number of transmigrated MB231 cells increased by 1.3-fold, 1.4-fold, and 1.6-fold, respectively, for 2), 3) and 4) VEGF treatments, compared to no treatment. Our results conform to our hypothesis that the reduced BBB GCX and enhanced MB231 GCX by VEGF favor MB231 adhesion to and transmigration across the BBB. Our findings also suggest a therapeutic intervention by targeting the glycocalyx-mediated breast cancer brain metastasis. Partially supported by NIH RO1NS101362 and 1UG3UH3TR002151. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.