Selective cytotoxicity of tunicamycin for transformed cells

Abstract

W e have studied the effects of tunicamycin, an inhibitor of dolichol pyrophosphate-dependent glycosylation of proteins, on the viability of transformed and non-transformed fibroblasts i n culture. W e have shown that a low concentration of tunicamycin (0.05 pg/ml o r 5 x M) is cytotoxic toward a variety of transformed cell lines, including virally o r chemically transformed fibroblasts from chick embryo, r a t kidney, human lung, and mouse. The corresponding non-transformed cell lines were resistant t o the same and a 10-fold higher concentration of tunicamycin. However, transformed permanent cell lines were also found t o be resistant t o tunicamycin. The relationship between transformation and tunicamycin cytotoxicity was strengthened by the finding that chick embryo fibroblasts infected by the temperature-sensitive viral mutants ts68 o r T5 are killed by the drug only at the temperature a t which transformation is expressed. The LD,, for sensitive transformed cell lines ranged from 0.02 t o 0.034pg/ml tunicamycin. Maximal cytotoxic effects t o transformed cells were produced a t tunicamycin concentrations which only slightly inhibited protein synthesis i n non-transformed cells (17.22% i n 24h). There was a good correlation between the susceptibility of transformed cells t o tunicamycin cytotoxicity and their sensitivity t o tunicamycin inhibition of protein glycosylation, 2-deoxy-D-glucose transport, and glucose metabolism. These results indicate that tunicamycin interferes with some cellular process critical for the survival of many transformed cells but not of non-transformed cells. W e speculate that the cytotoxicity of this drug towards transformed cells may result from impaired rates of nutrient transport, although other mechanisms are possible. Tunicamycin may, therefore, be therapeutically useful as an anti-tumor agent t o selectively kill certain types of malignant cells, while sparing nontransformed cells.

The role of glycoconjugates in metastatic melanoma blood‐borne arrest and cell surface properties

“…Duskin and Bornstein [50] found that tunicamycin was toxic to virally transformed mouse 3T3 and human WI-38 cells but not to the corresponding untransformed cell lines. Olden et a1 [51] confirmed this observation on a variety of fibroblast cell lines and also found that permanent transformed cell lines were resistant to tunicamycin treatment. However, even cells in which tunicamycin was not toxic showed reductions in their CR.429…”

“…Cell surface glycosaminoglycans are the other candidates for tunicamycin modification, because Satoh et a1 [58] demonstrated that B16 melanoma cells produce hyalurounic acid, chondroitin sulfate, and heparan sulfate. In addition, proteoglycan synthesis in chick embryo fibroblasts and embryonic chick cornea were inhibited by tunicamycin [51,591, and proteoglycans appear to be involved in cell adhesion to substratum [60, 611. bohydrates are important in the B16 melanoma metastatic process are consistent with previous reports [ 1 1, 14, 621. Elsewhere we have described the effects of tunicamycin on B 16-F1 and B 16-F10 cellular metabolism and glycoproteins synthesis in relation to the blood-borne arrest and lung colonization potentials [24].…”

Oligosaccharide modification by swainsonine treatment inhibits pulmonary colonization by B16-F10 murine melanoma cells.

“…This effect has been correlated with the presence of certain surface sialoglycoproteins (8,9,11). However, since tunicamycin is known to be toxic at least for most tumor cells (12,13), the significance of this finding remains unclear.…”

Carbohydrate requirement for expression and stability of acetylcholine receptor on the surface of embryonic muscle cells in culture.

“…The function of carbohydrate components of glycoproteins can be conveniently studied in cultured cells by the use of tunicamycin (TM), an antibiotic that specifically inhibits protein glycosylation (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). Treatment of cells with TM results in the synthesis of glycoproteins deficient in asparagine-linked oligosaccharides (6,18,19).…”