Correlation between p53 gene mutations and p53 protein accumulation evaluated by different methodologies

Mutations in the p53 gene are the most common genetic alterations in many t umour histotypes. Many of these mutations induce conformational changes res ulting in p53 protein stabilisation and consequently an accumulation detect able with immunochemical methods. Available data on the correlation between p53 gene alterations and p53 overexpression widely vary. In this study we analysed the correlation between p53 gene alterations detected by DGGE, SSC P and sequencing and protein expression detected by flow cytometric and imm unohistochemical approaches by using PAb 1801 antibody. The study was perfo rmed on 21 bladder tumours and 10 cell lines derived from different tumour histotypes as representative of different methodologic problems which can b e met starting from different types of biological material. The best correlation (81%) was observed between p53 mutations and FCM resul ts, using a double evaluation criterion for the latter which includes the p ercentage of positive cells and "delta values", evaluated as the difference between the mean values of Pab 1801 stained cells and isotypic control. Th e high correlation obtained between results from this FCM double criterion and p53 gene mutations is a good starting point for the analysis on large s eries of tumours and for a multiparameter FCM analysis including p53 protei n levels.