title: E-selectin binds to squamous cell carcinoma and keratinocyte cell lines.
abstract: E-selectin is an endothelial adhesion molecule that binds carbohydrate epitopes on leukocytes and has been implicated in a potential pathway of tumor metastasis. Keratinocyte cell lines express similar carbohydrate epitopes, one of which, sialyl Lewis X (SL-X) is a ligand for E-selectin and is also expressed by squamous cell carcinomas (SCC) in situ. The functional role of keratinocyte selectin ligands was investigated using a soluble E-selectin chimaeric protein (pE-sel-Ig) containing pig lectin-like and epidermal growth factor-like domains fused to human IgG. After incubation of keratinocyte cell lines (A431 and SVK14) and normal keratinocytes with pE-sel Ig, binding was quantified by flow cytometry. Frozen sections of SCC were overlaid with pE-sel Ig and binding was visualized immunoenzymatically. Immunolabeling was undertaken using monoclonal antibodies (CSLEX-1 and HECA-452), which label E-selectin ligands including sialyl Lewis X. E-selectin bound strongly to A431 and SVK14 cells; the degree of binding paralleled staining intensity with CSLEX-1 antibody. HECA-452 antibody stained A431 cells strongly but SVK14 cells only weakly. Normal keratinocytes and normal epidermis did not express CSLEX-1 or HECA-452 antigens or bind E-selectin. Serial sections of SCC revealed close correlation between fusion protein binding and antibody staining. Antibody pretreatment of tumor sections with CSLEX-1 blocked fusion protein binding, whereas HECA-452 antibody only slightly reduced fusion protein binding. pE-sel Ig pretreated with YT11.1 antibody failed to bind to A431 or SVK14 cells or to SCC. These studies provide functional evidence that SL-X/E-selectin pathways may be important in SCC metastasis and that A431 and SVK14 cells provide a good model to investigate these mechanisms.
authors.affiliation: Dunhill Dermatology Laboratory, St. John's Institute of Dermatology, London, U.K.
authors.forename: M H
authors.initials: MH
authors.lastname: Allen
authors.forename: M K
authors.initials: MK
authors.lastname: Robinson
authors.forename: P E
authors.initials: PE
authors.lastname: Stephens
authors.forename: D M
authors.initials: DM
authors.lastname: MacDonald
authors.forename: J N
authors.initials: JN
authors.lastname: Barker
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D002460:Cell Line; D019040:E-Selectin / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012878:Skin Neoplasms / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D019040:E-Selectin; D011993:Recombinant Fusion Proteins