Increase in nucleoli after x-radiation of fibroblasts of patients with Gorlin syndrome

Gorlin syndrome (GS) is an autosomal dominant disorder in which patients ar e abnormally susceptible to ionizing radiation with radiotherapeutic doses. Radiogenic basal cell carcinomas may develop with a short latent period in patients. The mechanisms underlying the abnormal radiosusceptibility of ce lls in patients with GS has not been well characterized. In this study we r eport an increase in the number of nucleoli in fibroblast cells from 3 pati ents with GS after x-radiation. In GS fibroblasts, the increase in nucleolu s number concomitant with the increase of ribonucleoprotein immunoreactive aggregates within the nucleus was observed after x-radiation, whereas signi ficant change was not found in normal fibroblasts derived from healthy dono rs. This increase disappeared when cells were cultured with the RNA synthes is inhibitor actinomycin D after x-radiation but not when they were culture d with cycloheximide or aphydicolin, which are protein and DNA synthesis in hibitors, respectively. Ultraviolet exposure did not induce remarkable chan ges in the GS nucleoli. Thus the increase in nucleoli was induced after x-r adiation of GS fibroblasts, and this increase seemed to be related to RNA s ynthesis metabolism.