Factors Affecting and Significance of G2 Chromatin Radiosensitivity in Predisposition to Cancer

SummaryThe frequencies of chromatid breaks and gaps in metaphase cells fixed 2 h after G2 phase X-irradiation (1 Gy) were in almost all cases at least two- to three-fold higher in skin fibroblasts from individuals with genetic conditions predisposing to cancer than in comparable cells from clinically normal controls. Previously, we reported this response in all cancer-prone genetic disorders tested including ataxia telangiectasia, Bloom's syndrome, Fanconi's anemia, xeroderma pigmentosum (XP), familial polyposis, Gardner's syndrome, hereditary malignant melanoma, dysplastic nevus syndrome and cancer family members. One exception was XP-A. In this report we add information on skin fibroblasts from retinoblastoma, Wilms' tumor and XP-C patients, 13 clinically normal controls and six cell lines from fetal or infant cells. Factors affecting the response are identified and include pH, temperature, cell density, culture medium or serum, microbial contamination and visible light exposure (effective wavelength 40...