Normal repair of gamma radiation-induced single-strand and double-strand DNA breaks in retinoblastoma fibroblasts

Abstract

The formation and repair of γ radiation-induced DNA damage were examined in fibroblasts from individuals with retinoblastoma. Utilizing the alkaline elution technique to study single-strand DNA breaks and the nondenaturing elution technique to study double-strand DNA breaks, cultured cell strains from two patients with bilateral retinoblastoma and one patient with sporadic retinoblastoma were shown to develop the same number of DNA breaks as cells from normal individuals after exposure to various γ radiation doses. Furthermore, the rate and extent of rejoining of both single- and double-strand DNA breaks induced by γ radiation in retinoblastoma fibroblasts were also normal. Defective DNA break repair does not appear to explain the marked predisposition to second malignancies and the possible in vitro radiation sensitivity which are associated with hereditary retinoblastoma.