P53 mutation and expression in lymphoma.

Dja Adamson,Ne Haites,B Bennett,Aa Dawson,Wd Thompson

doi:10.1038/bjc.1995.292

Abstract

Mutation and abnormal expression of p53 was studied in 38 lymphomas [five Hodgkin's disease and 33 non-Hodgkin's lymphoma (NHL)]. CM1 polyclonal antibody was used to detect overexpression of p53. Three missense mutations were characterised in three cases of NHL after screening exons 5-8 of p53 of all the tumours with single-strand conformation polymorphism (SSCP) analysis. Only two out of three tumours with a missense mutation showed abnormal expression of p53 as measured by CM1. Conversely, seven out of nine tumours with positive CM1 staining had no point mutation demonstrated. Overexpression of p53 in the cases of NHL occurred in three out of twenty four low-grade tumours and five out of nine high-grade tumours (Kiel classification). The results suggest that abnormalities of p53 are commoner in high-grade than low-grade NHL, and that positive immunocytochemistry cannot be used to determine which tumours have mutations of p53.

Highlights

S _nary Mutation and abnormal expression of p53 was studied in 38 lymphomas [five Hodgidn's disease and 33 non-Hodgkin's lymphoma (NHL)J
The results suggest that abnormalities of p53 are commoner in high-grade than low-grade NHL, and that positive immunocytochemistry cannot be used to determine which tumours have mutations of p53
Apoptotic response to radiation damage depends on normal p53 function - thymocytes from p53 knock-out mice are resistant to more than 20 Gy while control thymocytes show apoptosis at 1 Gy (Lane, 1993). p53 is involved in the therapeutic response to the topoisomerase 2 inhibitor, etoposide, by facilitating apoptosis (Clarke et al, 1993)

Summary

Materials and methods

Approval for the study was obtained from the local Joint Ethics Committee. Tumour samples of Hodgkin's disease and non-Hodgkin's lymphoma (NHL) were collected both fresh from surgical theatres and from samples received in the Department of Pathology, Aberdeen Royal Infirmary, from 1987 onwards and stored at -70°C. Most 'tumour' DNA control was 'amplified' and run to detect PCR contamination and positive controls (samples with known mobility shifts) were run on each gel. The sections stained with CM1 polyclonal antibody were taken from tumour immediately adjacent to that from which DNA was extracted for SSCP analysis. This could not be guaranteed for every H&E-stained section as some of these were taken from the pathology archives. Cases were selected on the basis that either fresh or archival frozen material was available to provide sections for CM1 staining and for DNA extraction. The antisense primer was biotinylated (exon 6, King's College, London; exons 5, 7 and 8, Genosys Biotechnologies, Cambridge, UK) at the 5' end to enable purification of the single-stranded template using streptavidin-conjugated magnetic beads

DNA extraction

Lymphoyte Nodular sclerosis Mixed cellularity Lymphocyte depletion

Findings

CMI positiity