IMMUNOHISTOCHEMICAL STUDY OF P53 PROTEIN IN HUMAN AND ANIMAL PITUITARY-TUMORS

In many human cancers, p53 gene mutations are frequently occurring gen etic abnormalities, which may be detected by immunohistochemical stain ing for p53 protein. In the present study, p53 immunoreactivity was in vestigated in formalin-fixed, paraffin-embedded tissues from human and animal pituitary tumors, using the avidin-biotin-peroxidase complex t echnique. No p53 was detected in 3 nontumorous human adenohypophyses o r in 40 human pituitary tumors including 5 GH cell adenomas, 10 PRL ce ll adenomas, 2 mixed GH cell-PRL cell adenomas, 2 acidophil stem cell adenomas, 8 ACTH cell adenomas, 1 TSH cell adenoma, 1 FSH/LH cell aden oma, 5 null cell adenomas, 5 oncocytomas, and 1 plurihormonal adenoma. Twenty nontumorous and hyperplastic pituitaries of hGRH transgenic mi ce and 8 tumors in these transgenic animals were immunonegative for p5 3. All pituitary tumors found in AVP/SV40 transgenic mice contained p5 3 immunoreactivity in the nuclei, while the nontumorous adenohypophysi s of one such transgenic mouse was negative. It can be concluded that p53 mutations are apparently not involved in the pathogenesis of human pituitary adenomas or of the pituitary tumors which develop in hGRH t ransgenic mice. However, pituitary tumors in AVP/ SV40 transgenic mice are accompanied by p53 expression.