Abstract
A growing body of evidence suggests that L-selectin ligands presented on circulating tumor cells facilitate metastasis by binding L-selectin presented on leukocytes. Commonly used methods for detecting L-selectin ligands on tissues, e.g., immunostaining, are performed under static, no-flow conditions. However, such analysis does not assay for functional L-selectin ligands, specifically those ligands that promote adhesion under shear flow conditions. Recently our lab developed a method, termed dynamic biochemical tissue analysis (DBTA), to detect functional selectin ligands in situ by probing tissues with L-selectin-coated microspheres under hemodynamic flow conditions. In this investigation, DBTA was used to probe human colon tissues for L-selectin ligand activity. The detection of L-selectin ligands using DBTA was highly specific. Furthermore, DBTA reproducibly detected functional L-selectin ligands on diseased, e.g., cancerous or inflamed, tissues but not on noncancerous tissues. In addition, DBTA revealed a heterogeneous distribution of functional L-selectin ligands on colon cancer tissues. Most notably, detection of L-selectin ligands by immunostaining using HECA-452 antibody only partially correlated with functional L-selectin ligands detected by DBTA. In summation, the results of this study demonstrate that DBTA detects functional selectin ligands to provide a unique characterization of pathological tissue.
Highlights
The overexpression of sialofucosylated glycans on colon cancer cells is linked with poor prognosis [1]
This result was anticipated because the HECA-452 monoclonal antibodies (mAbs) was expected to bind purported L-selectin ligands with greater affinity than the L-selectin protein in IF assays [19, 20, 30, 31]
Selectin/ligand interactions may facilitate the adhesion of circulating tumor cells (CTCs) with hematopoietic cells and vascular endothelial cells to promote cancer metastasis [1, 53,54,55,56,57,58]
Summary
The overexpression of sialofucosylated glycans on colon cancer cells is linked with poor prognosis [1]. Specific sialofucosylated carbohydrate decorations, e.g., sialyl Lewis x (sLex), have been implicated as adhesion molecules that promote colon cancer metastasis [2]. Mounting evidence suggests that during metastasis sialofucosylated glycans expressed on circulating tumor cells (CTCs), which intravasate into blood from a primary tumor, mediate adhesion with selectin molecules expressed by hematopoietic cells in the blood stream. PLOS ONE | DOI:10.1371/journal.pone.0173747 March 10, 2017
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