DIMETHYL-SULFOXIDE (DMSO) INCREASES EXPRESSION OF SIALYL LEWIS-X ANTIGEN AND ENHANCES ADHESION OF HUMAN GASTRIC-CARCINOMA (NUGC4) CELLS TO ACTIVATED ENDOTHELIAL-CELLS

Dimethyl sulfoxide (DMSO) exerts a number of biological effects includ ing the promotion of cell differentiation in cultured cells. In this s tudy, we examined the effect of DMSO on the adhesion of tumor cells to endothelial cells. In vitro treatment of human gastric adenocarcinoma (NUGC4) cells with DMSO resulted in increased adhesion to interleukin -1 (IL-1)-activated human endothelial cells compared with DMSO-untreat ed NUGC4 cells. In flow cytometry, treating NUGC4 cells with DMSO enha nced the expression of sialyl Lewis x (sialyl Le(x)) and sialyl dimeri c Le(x) antigens on their surface. Also, the binding of Limulus polyph emus agglutinin (LPA), which specifically binds to cell-surface sialic acids, was increased by DMSO. The adhesion of DMSO-treated NUGC4 cell s to activated endothelial cells was blocked by neuraminidase pre-trea tment of tumor cells or by antibody against either endothelial leukocy te adhesion molecule-1 (ELAM-1) or sialyl Le(x). Thus, it is suggested that enhanced adhesion following DMSO treatment is mediated by the in teraction of sialyl Le(x) expressed on NUGC4 cells with ELAM-1 of endo thelial cells. The modulation of sialyl Le(x) antigen by DMSO provides a useful system for studying the regulatory mechanism of Lewis-relate d carbohydrate antigens and also for understanding the metastatic prop erties of cancer cells.