title: High frequency of p53 protein expression in thymic carcinoma but not in thymoma.
abstract: Thymic epithelial tumours are broadly classified into thymomas and thymic carcinomas. Although both tumours occasionally show invasive growth, they exhibit different clinical and biological findings. The oncogene and anti-oncogene in thymic epithelial tumours have not been evaluated fully. We investigated the expression of p53 protein by immunohistochemical analysis using the anti-p53 polyclonal antibody (CM-1) in 17 thymomas and 19 thymic carcinomas. We also examined p53 gene (exon 5-8) mutation in 18 thymic carcinomas by using polymerase chain reaction-single-strand conformation polymorphism methods and direct sequencing. Of the thymoma cases, only one invasive thymoma showed focal nuclear staining. Fourteen of the 19 thymic carcinomas (74%) showed nuclear staining. Point mutations of the p53 gene were recognized in only 2 of the 18 thymic carcinomas (11%). One was the mutation C to T transition in the first letter of codon 222 in exon 6, which results in the amino acid substitution from proline to serine. Another was a silent mutation. p53 protein accumulation is highly frequent in thymic carcinomas but not in thymomas, and gene mutation is uncommon in thymic carcinomas.
authors.affiliation: Second Department of Surgery, School of Medicine, The University of Tokushima, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Hino
authors.forename: K
authors.initials: K
authors.lastname: Kondo
authors.forename: T
authors.initials: T
authors.lastname: Miyoshi
authors.forename: T
authors.initials: T
authors.lastname: Uyama
authors.forename: Y
authors.initials: Y
authors.lastname: Monden
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000032:analysis; D051736:Proto-Oncogene Proteins c-mdm2; D013945:Thymoma / Q000737:chemistry*; D013953:Thymus Neoplasms / Q000737:chemistry*; D016159:Tumor Suppressor Protein p53 / Q000032:analysis*
chemical_list: D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2