Abnormal DNA Synthesis Activity Induced by X-Rays in Nevoid Basal Cell Carcinoma Syndrome Cells
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文摘
DNA synthesis activity was examined in fibroblasts and isolated nuclei derived from patients with nevoid basal cell carcinoma syndrome (NBCCS) upon exposure to X-ray and ultraviolet (UV). The DNA synthesis activity in NBCCS fibroblasts increased after X-ray irradiation, i.e., to twice that on mock-irradiation, while it decreased in healthy donor-derived fibroblasts. The DNA synthesis activity in isolated nuclei of X-ray irradiated NBCCS fibroblasts also increased, i.e., more than twice that on mock-irradiated. In the experiments using synchronized cells, DNA synthesis activity showed the most marked increase when the fibroblasts at S phase were irradiated with X-rays. In contrast, UV-irradiated NBCCS fibroblasts showed no such increase in DNA synthesis. These results revealed that DNA synthesis is abnormally induced in X-ray irradiated NBCCS cells and that this abnormality might be related with the tendency of tumorigenesis in NBCCS patients after exposure to X-ray.