Hypersensitivity of cultured ataxia-telangiectasia cells to etoposide

Fibroblasts from patients with ataxia-telangiectasia (A-T) were found to be hypersensitive to killing by the antineoplastic agent etoposide. The A-T fibroblast strains GM5823, GM367, and GM2052 were twofold to threefold more sensitive to killing by etoposide than fibroblasts from normal controls (AG1521, AG1522, and IMR90). A simian virus 40 (SV40)-transformed, immortal human fibroblast line (GM5849) derived from the A-T cell line GM5823 was also studied. GM5849 retained the unusual sensitivity of nontransformed A-T fibroblast lines to x-irradiation, bleomycin, and neocarzinostatin (zinostatin). GM5849 was also more sensitive to etoposide than were SV40-transformed fibroblasts from normal controls. M1, and SV40-transformed fibroblast line derived from a patient with xeroderma pigmentosum, had the same sensitivity to etoposide as SV40-transformed fibroblasts derived from normal controls.