(447d) Identification of Nucleolin As a Novel L-Selectin Ligand Expressed on Head and Neck Squamous Carcinoma Cells

Head and neck squamous cell carcinoma (HNSCC) cells bind to lymphocytes via L-selectin in a shear-dependent manner. This interaction takes place exclusively under low shear stress conditions (i.e., less than 0.1 dyn/cm²), such as those found within the lymph node parenchyma, representing a novel functional role for L-selectin/selectin ligand interactions. Our previous published work characterized as-of-yet unidentified L-selectin ligands expressed by HNSCC cells that are specifically active under conditions of low shear stress. Using affinity purification followed by mass spectrometry and other molecular characterization techniques, we have identified nucleolin expressed on the cell surface of HNSCC cells as a ligand for L-selectin. Parallel plate chamber flow chamber experiments and atomic force microscopy (AFM) experiments verify that nucleolin binds to L-selectin specifically and in a force-dependent manner. Thus, our results reveal nucleolin as the first major L-selectin ligand that operates under low shear stress conditions.