P53 GENE AND CELL CYCLING IN UVEAL MELANOMA

PURPOSE: To determine whether alterations of p53, a tumor suppressor g ene, were present in uveal melanoma, and to characterize further the n ature of those changes. METHODS: Immunohistochemical analysis with a m onoclonal antibody was used to determine whether alterations of p53 we re present in 35 enucleated archival uveal melanomas. Further characte rization was done by comparing the p53 gene and cell cycling status by using bromodeoxyuridine staining, The alterations in p53 were charact erized using polymerase chain reaction single-strand conformational po lymorphism analysis and sequencing. RESULTS: Four of 35 uveal melanoma s showed low levels (0.5% to 5.0%) of positive immunostaining for alte red p53 in tumor cell nuclei using monoclonal antibody DO-7, These fou r tumors had the three highest and the 14th highest bromodeoxyuridine labeling indices, ranging from 1.3% to 7.0%. Polymerase chain reaction single-strand conformational polymorphism analysis of p53 exons 5 to 8 was performed on three p53-positive and six p53-negative tumors, and no altered motility shifts were detected. Sequencing of one of the po sitive staining specimens confirmed no mutations in exons 5 through 8 in the p53 gene. Double immunohistochemical labeling for both bromodeo xyuridine and p53 in one tumor showed that most of p53-positive cells were in S phase. CONCLUSIONS: Mutation of p53 is an uncommon event in uveal melanomas. Nuclear accumulation of p53 protein was found in thre e of the four tumors with the highest levels of cell cycling.