Abstract P2-05-18: Mesofluidic platform for high throughput screening of inhibitors of metastasis

A fundamental limitation in the development of new therapies to prevent metastatic cancer is a lack of in vitro systems that can accurately recapitulate the steps of cancer cell metastasis. Currently, most assays for examining the steps of metastasis fail to incorporate the biophysical forces experienced by tumor cells due to blood flow, or are low throughput and thereby not amenable to drug screens or high throughput experimentation. We have developed a novel high throughput mesofluidic platform for assaying cell adhesion under flow in a 96-well format. This device functions like a cone and plate viscometer in each well by inducing shear stress on cells cultured in a standard 96-well plate. We validated the fluid flow and alignment of the device and studied the adhesion of cultured leukocytic monocytes (THP-1 cells) and multiple cancer cell lines (MDA-MB-231 and MCF-7 breast cancer cell lines) to purified extracellular matrix molecules (ECM), endothelial cells and immobilized platelets. Assays were carried out under flow (0.5 dynes/cm 2 shear stress) and static conditions. Our studies show that adhesion assays performed under flow yield markedly different results from static adhesion assays. Treatment of breast cancer cells with a small library of integrin inhibitors demonstrated that these compounds had minimal effect on cancer cell adhesion to endothelial cells or immobilized platelets under static conditions, whereas under shear conditions many of these compounds significantly reduced adhesion of cancer cells. As well, this experiment elucidated integrins important for breast cancer adhesion to endothelial cells and platelets. A static adhesion assay of breast cancer cells to various types of ECM showed greater adhesion of the less aggressive MCF-7 cell line in comparison to the more aggressive MDA-MB-231 cell line. In contrast, flow incorporating assays showed increased adhesion of the more aggressive MDA-MB-231 breast cancer cell line. Specifically, the shear assay saw a significant increase in adhesion for multiple ECM as well as an increase in the strength of adhesion to laminin. Finally, we performed a high throughput screening experiment using a kinase inhibitor library of 80 compounds and found that the shear based assay yielded notably different results from a similar screen under static conditions for breast cancer cell adhesion to endothelial cells, immune cell adhesion to endothelial cells and breast cancer cell adhesion to platelets. This shear experiment yielded seven "hits", many of which match targets of drugs in clinical trials. In conclusion, our studies show that adhesion assays performed under flow yield markedly different results from static adhesion assays, and are better at identifying both aggressive cancer cells lines and known pathways for circulating cancer and immune cell adhesion. Thus, this high-throughput screening platform may enable the development of novel compounds to inhibit cancer metastasis and facilitate the study of the systems level behavior of cancer-endothelium adhesion. Citation Format: Spencer A, Spruell C, Nandi S, Le V, Crexiell M, Dunn AK, Baker AB. Mesofluidic platform for high throughput screening of inhibitors of metastasis. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-05-18.