Response of malignant and nonmalignant epidermal cell lines to tunicamycin

Exposure of fibroblasts to tunicamycin has been found to be cytotoxic for transformed cells, but not for nontransformed cells. With two mouse epidermal cell lines of common origin, we observe a contrary pattern: The malignant cells are more resistant to tunicamycin than their nonmalignant counterparts, as measured by growth and viability. With respect to the glycosylation of sugar precursors, the incorporation of mannose is more inhibited than that of glucosamine, while fucose is least impacted. Sugar incorporation is less reduced for the malignant cells, by a factor of two for fucose and more modestly for the other two sugars. There are no significant morphological changes; in particular, the desmosomal junctions are not affected. On polyacrylamide gels, we note intensity variations in several protein bands in response to tunicamycin, but little difference between malignant and nonmalignant cells when using either Coomassie stains or Concanavalin A overlays.