Abstract 4566: Dynamic biochemical tissue analysis: A novel in situ assay that demonstrates potential as a diagnostic/prognostic for cancer

Abstract

Abstract Work in the field of cell adhesion has undeniably shown that the full spectrum of molecular bond properties is germane to biological recognition and communication in physiologic and pathologic conditions, including cancer. For example, the unique kinetic and tensile properties of E-selectin bonds allow it to mediate cancer cell adhesion to the endothelium and leukocyte recruitment to sites of inflammation. Typically in a biochemical tissue analysis (e.g., immunohistochemistry), a molecular probe (e.g., antibody) detects antigens by utilizing only one property of the probe-antigen bond, specifically affinity, and other aspects of the bond (e.g., dynamic biophysical properties) remain unexploited. Therefore, we developed a dynamic biochemical tissue analysis (DBTA) that allows exquisite control over the interaction between the probe and the antigen to enhance characterization of molecular recognition in situ. Specifically, we conjugated a recombinant E-selectin construct to polystyrene microspheres and used the resulting microspheres as the probe to investigate E-selectin ligand activity on colon cancer, breast cancer, and normal tissues using DBTA. When E-selectin microspheres were perfused over invasive colon adenocarcinoma tissue sections at a wall shear stress of 0.80 dynes/ cm2, the microspheres exhibited robust adhesion with the tissue. The adhesion of E-selectin microspheres was significantly higher than that of negative control (IgG conjugated) microspheres, demonstrating the specificity of interaction of E-selectin microspheres with the tissue sections. To demonstrate that modulating easily controlled assay parameters results in discernible changes in adhesion, E-selectin microspheres of 10 and 15 µm diameters were perfused over the colon adenocarcinoma tissue sections at different levels of shear stress, achieved by varying the volumetric flow rate. The results showed that with increasing shear stress or particle diameter, the adhesion of E-selectin microspheres to the tissue sections decreased as predicted. To demonstrate that DBTA can be used for high throughput analysis, colon and breast cancer tissue microarrays were used. These microarray slides consisted of tissues from various histopathological classifications. E-selectin microspheres exhibited higher adhesion than the IgG microspheres to the majority of the cancer tissues, showing the preferential expression of functional E-selectin ligands on cancer tissues. Combined the results (i) convincingly demonstrate the specificity of the DBTA assay, (ii) reveal the critical role physical factors play in tissue analysis and (iii) demonstrate that DBTA allows facile control over these key physical factors. Thus, we have established a new approach for characterizing tissue that will lead to novel diagnostic and prognostic assays for a large spectrum of pathologies including cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4566. doi:1538-7445.AM2012-4566