Disialylgalactosylgloboside (DSGG), defined by monoclonal antibody RM2, is a renal cell carcinoma (RCC)-associated antigen which mediates adhesion of RCC TOS-1 cells to certain lung tissue target cells. This adhesion process may initiate preferential lung metastasis of RCC. Ganglioside GM3 is a B16 melanoma-associated antigen which similarly adheres to target cells and promotes consequent metastasis. In view of the close association of GM3-enriched microdomain with transducer molecules c-Src, Rho A, and FAK in B16 cells, we investigated the organizational status of DSGG in RCC cell line TOS-1, with the following results: i) DSGG, but not monosialylgalactosylgloboside, showed extensive clustering at the TOS-1 cell surface; ii) a low-density membrane fraction isolated from TOS-1 cells contained >95% of cellular DSGG, although protein content in this fraction was <1% of total cellular protein; iii) this fraction contained c-Src, Rho A, and FAK, but not H-Ras; iv) c-Src and Rho A were co-immunoprecipitated with DSGG through anti-DSGG mAb RM2 (IgM) affixed to a column. These observations indicate that DSGG is clustered in RCC, as typified by TOS-1 cells, to form a microdomain in which it is closely associated with c-Src, Rho A, and FAK, and may constitute a functional unit as has been observed for GM3 with transducer molecules in B16 cells. The functional organization of such units may be essential in determining malignant properties of RCC cells.
ASJC Scopus subject areas
- Cancer Research