Abstract 3991: Differentiating esophageal cancer cells from normal cells using ligand-conjugated microspheres

Cancer of the esophagus has a dismal overall prognosis and low 5 year survival rate due to its aggressive nature and the fact that it often presents at a late stage. Biochemical changes present on transforming tissue provide an opportunity for the early detection of cancer within the esophagus and thus the promise of a more favorable prognosis and a higher survival rate. Recently, there has been an increasing effort to detect cancer of the esophagus by introducing, during an endoscopic procedure, soluble molecules (ligands) cognate to moieties preferentially expressed on transforming tissue. The success of this approach depends on the selective binding of the ligand to transforming tissue relative to normal tissue. For soluble ligands, the factors that dictate the selective binding depend on a very small number of factors. In contrast, if the ligands are conjugated to particles, there are a large number of controllable factors that can be manipulated to “engineer” the detection scheme and thus optimize selective recognition of transforming tissue. In this study, we utilized an in vitro system to investigate the feasibility of the ligand-conjugated particle approach. First, we explored the surface chemistry of an esophageal adenocarcinoma cell line, OE19, relative to a normal esophageal cell line, HEEpiC, using flow cytometric analysis. Among other differences, we found that the OE19 cell line expresses relatively high levels of the tetrasaccharides sialyl Lewis A (sLea) and sialyl Lewis X (sLex). sLea and sLex are known cognate molecules for the selectin family of adhesion molecules, in particular E-selectin. Thus, we conjugated an E-selectin construct to 10 μm diameter microspheres. The E-selectin construct consisted of the extracellular domain of E-selectin fused to the Fc domain of IgG. Flow cytometric analysis revealed that the E-selectin construct was conjugated to the microspheres and that the E-selectin portion of the molecule was available for binding. To roughly simulate the introduction of the conjugated microspheres during an endoscopic procedure, a parallel plate flow chamber was used. A planar substrate of either OE19 or HEEpiC cells was placed in the flow chamber and a suspension of E-selectin or IgG (negative control) microspheres were perfused through the flow chamber. We observed that the E-selectin microspheres exhibited significantly greater adhesion to the OE19 cells relative to the HEEpiC cells. In contrast, IgG microspheres exhibited