Discriminating functional and non-functional p53 in human tumours by p53 and MDM2 immunohistochemistry

• Published in: The Journal of pathology Vol. 207; no. 3; pp. 251 - 259
• Main Authors: Nenutil, R, Smardova, J, Pavlova, S, Hanzelkova, Z, Muller, P, Fabian, P, Hrstka, R, Janotova, P, Radina, M, Lane, DP, Coates, PJ, Vojtesek, B
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.11.2005; Wiley
• Subjects: Adenocarcinoma - genetics; Adenocarcinoma - pathology; Biological and medical sciences; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Carcinoma, Squamous Cell - genetics; Carcinoma, Squamous Cell - pathology; Cyclin-Dependent Kinase Inhibitor p21 - genetics; DNA, Neoplasm - genetics; Endometrial Neoplasms - genetics; Endometrial Neoplasms - pathology; Female; Genes, p53 - genetics; Humans; immunohistochemistry; Immunohistochemistry - methods; Investigative techniques, diagnostic techniques (general aspects); Ki-67 Antigen - genetics; MDM2; Medical sciences; Mutation; Neoplasms - genetics; Neoplasms - pathology; Ovarian Neoplasms - genetics; Ovarian Neoplasms - pathology; p53; p53 phosphorylation; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Phosphorylation; Proto-Oncogene Proteins c-mdm2 - genetics; TP53 mutation; Transcription, Genetic - genetics; Tumor Suppressor Protein p53 - genetics; Uterine Cervical Neoplasms - genetics; Uterine Cervical Neoplasms - pathology; Human; Immunohistochemistry; Phosphorylation; TP53 mutation; p53; Anatomic pathology; TP53 Gene; MDM2; Genetics; Tumor; Mutation; p53 phosphorylation; Tumor suppressor gene
• ISSN: 0022-3417; 1096-9896
• DOI: 10.1002/path.1838

Mutation and/or loss of the TP53 tumour suppressor gene is the single most common genetic abnormality in human cancer. The majority of TP53 mutations lead to stabilization of the protein, so that immunohistochemical staining for p53 can suggest mutation status in many cases. However, various false‐positive and false‐negative situations mean that simple immunostaining for p53 is not informative in a substantial number of tumours. In the present study, a series of 119 human cancers were immunostained using a highly sensitive technique that detects the low levels of wild‐type protein expressed in normal cells, such that homozygous gene deletion or non‐sense TP53 mutation can be identified by an absence of staining. TP53 gene status was also assessed using FASAY as a genetic/functional screen and in selected cases by direct sequencing. A quantitative scoring system was employed to assess p53 levels, and p53 post‐translational modification was evaluated using antibodies that detect specific phosphorylation sites. Phosphorylated p53 correlated with total p53 levels and did not improve the prediction of TP53 mutation status. The transcriptional activity of TP53 was determined by staining for two downstream target genes, p21WAF1 and MDM2, and statistical correlations between MDM2/p21WAF1 and p53 were found in tumours with wild‐type, but not mutant TP53. Measurement of staining for p53 and MDM2 accurately identifies the TP53 status of tumours. This simple and cost‐effective method, applicable to automated staining and quantitation methods, improves the identification of TP53 status over standard methods for p53 immunostaining and provides information about tumour p53 phenotype that is complementary to genotyping data. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.