IMMUNOHISTOCHEMICAL EXPRESSION OF P53 PROTEINS IN WILMS-TUMOR - A POSSIBLE ASSOCIATION WITH THE HISTOLOGICAL PROGNOSTIC PARAMETER OF ANAPLASIA

Wilms' tumour (nephroblastoma) has been associated with chromosomal ab normalities at the 11p13, 11p15 and 16q regions. A study into the poss ibility of mutations occurring within p53, the ubiquitous adult tumour suppressor gene, in Wilms' tumour was carried out, Thirty-eight cases were studied, Of these 36 were categorised into the favourable histol ogy group and two into the unfavourable histology group based on the N ational Wilms' Tumour Study criteria, Archival formalin-fixed, paraffi n-embedded tissue sections from each case were stained with a polyclon al (AB565:Chemicon) and a monoclonal (DO7:Dako) antibody raised agains t p53 protein using a peroxidase-labelled streptavidin biotin kit (Dak o). 'Cure' (disease-free survival of 60 months or longer) was document ed in 39% of cases with favourable histology tumours, Eleven percent i n this group succumbed to the disease. Both cases with unfavourable hi stology died, Four out of 36 (11%) tumours with favourable histology d emonstrated weak to moderate staining with both AB565 and DO7 in more than 75% of tumour cells, In contrast, p53 protein expression in unfav ourable histology tumours was significantly increased compared with th e favourable histology group (P = 0.021) with both cases demonstrating immunopositivity in >75% of tumour cells when stained with AB565 and DO7, The intensity of staining ranged from moderate to strong in both cases. It appears from this preliminary study that the immunohistochem ical expression of p53 protein in Wilms' tumour, presumably a result o f mutation in the p53 tumour suppressor gene, correlates with histolog ical classification, histological categorisation being one of the usef ul features in the prognostic assessment of Wilms' tumours.