(582f) Dynamic Adhesion Assays for Understanding the Significance of CD151 in the Metastatic Cascade

Cancer is the second leading cause of death in the United States, with metastatic lesions resulting from circulating tumor cells (CTCs) most often causing the mortality.  The basic steps of the metastatic cascade, from initial tumor formation to growth at a secondary site, are a linear sequence of steps composed of a network of mechanisms that are not well understood.  One of these steps, the adhesion of cancer cells to endothelial cells during dissemination, is the focus of this research.  Specifically, the influence of CD151, a gene that encodes a cell surface glycoprotein that is known to complex with integrins and enhance cancer cell motility, invasion and metastasis was studied.  To study the influence of CD151, a prostate cancer cell line (PC3) and a breast cancer cell line (MCF-10A) were employed in dynamic adhesion assays in which the expression of CD151 was knocked down on the cancer cells using shRNA gene silencing.  Both the knocked down and unmodified lines were utilized to quantify adhesive strength and frequency of adherence to flow-adapted cell monolayers composed of Human Umbilical Vein Endothelial Cells (HUVECs).  A parallel plate flow chamber system was utilized to investigate these properties under flow at various shear stresses ranging from 0.25 dynes/cm² to 15 dynes/cm² to cover the range of most physiologically relevant shears.  Brightfield and fluorescent images were analyzed to determine cancer cell adherence over time as well as retention rates after a light wash and a period of subjection to a given shear stress.  Preliminary results indicated that the presence of CD151 leads to enhanced initial adhesion of prostate cancer cells to statically-grown HUVECs in adhesion trials, but retention rates appeared to be unaffected by CD151 expression once those cells became firmly adhered. Results from PC3 and MCF-10A adhesion to flow adapted endothelial monolayers will be presented.