Cancers of the digestive tract cause nearly one quarter of the cancer deaths worldwide, and nearly half of these are due to cancers of the esophagus and colon. Early detection of cancer significantly increases the rate of survival, and thus it is critical that cancer within these organs is detected early. In this regard, endoscopy is routinely used to screen for transforming/cancerous (i.e. dysplastic to fully cancerous) tissue. Numerous studies have revealed that the biochemistry of the luminal surface of such tissue within the colon and esophagus becomes altered throughout disease progression. Molecular endoscopic imaging (MEI), an emerging technology, seeks to exploit these changes for the early detection of cancer. The general approach for MEI is as follows: the luminal surface of an organ is exposed to molecular ligands, or particulate probes bearing a ligand, cognate to biochemistry unique to pre-cancerous/cancerous tissue. After a wash, the tissue is imaged to determine the presence of the probes. Detection of the probes post-washing suggests pathologic tissue. In the current review we provide a succinct, but extensive, review of ligands and target moieties that could be, or are currently being investigated, as possible cognate chemistries for MEI. This is followed by a review of the biophysics that determines, in large part, the success of a particular MEI design. The work draws an analogy between MEI and the well-advanced field of cell adhesion and provides a road map for engineering MEI to achieve assays that yield highly selective recognition of transforming/cancerous tissue in situ.

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 negligible adhesion to the OE19 and HEEpiC cells. Combined, this study provides proof of concept for an assay approach that could be engineered to detect transforming tissue present within the esophagus. Citation Format: Mahboubeh S. Noori, Sarah J. Bodle, Grady E. Carlson, David S. Drozek, Monica M. Burdick, Douglas J. Goetz. Differentiating esophageal cancer cells from normal cells using ligand-conjugated microspheres. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3991.