P53 MUTATIONS IN ADRENAL-TUMORS - CAUCASIAN PATIENTS DO NOT SHOW THE EXON-4 HOT-SPOT FOUND IN TAIWAN

Mutations in the p53 tumor suppressor gene are frequently present in h uman cancers but have rarely been described in benign tumors. We previ ously reported mutations in the ''hot spots'' between exons 5-8 of the p53 gene in adrenocortical carcinomas but not in adenomas. Recently, a previously unknown hot spot in exon 4 of the p53 gene was described in adrenal adenomas and pheochromocytomas of Taiwanese patients. We, t herefore, investigated whether these mutations are also present in Cau casian patients from the U.S. and Europe. We analyzed tumor tissue of 12 aldosterone-producing adenomas, 7 cortisol-producing adenomas, and 6 pheochromocytomas. Overexpression of the p53 protein was investigate d by immunohistochemistry. Point mutations within exon 4 were identifi ed by polymerase chain reaction (PCR) amplification and direct sequenc ing of the PCR product. The pYNZ22 microsatellite located on chromosom e 17p, close to the p53 gene, was used to screen for allelic loss (LOH ) of the p53 gene. Overexpression of p53 was not identified in any of the adenomas and pheochromocytomas. Point mutations within exon 4 were found in 0/25 tumors. LOH was present in 1/13 informative adenomas an d 0/2 informative pheochromocytomas. We conclude that p53 mutations do not play a major role in the tumorigenesis of adrenal adenomas and ph eochromocytomas of Caucasian patients. Thus, ethnic and environmental factors may be responsible for the mutational spectrum found in Taiwan ese patients.