Prognostic factors in astrocytomas: relationship of p53, MDM-2, BCL-2 and PCNA immunohistochemical expression to tumor grade and overall patient survival.

The immunohistochemically detected expression of p53, BCL-2, MDM-2 and PCNA proteins in samples of tumor tissues of 42 patients with astrocytomas or glioblastoma multiforme was statistically compared to degree of malignancy and overall survival. We found relation between p53 protein expression and survival in the high grade astrocytomas group (more cases of p53 immunonegative tumors with longer survival), and significantly higher BCL-2 protein expression as well as significantly higher MDM-2 protein expression in the group of low grade astrocytomas. PCNA protein expression showed any relation to tumor grade or survival. Despite the rather small number of samples these results support the hypothesis that MDM-2 protein may be a potent regulator of functional p53, expressed in low grade astrocytoma only.

Immunoreactivity of new antibodies anti-p53 and anti-MDM-2 in paraffin embedded tissue samples.

Detection of various epitopes of the p53 and MDM-2 proteins, using new antibodies was performed on formalin-fixed and paraffin-embedded tissue samples from breast cancer and compared with results obtained using well-characterized antibodies. The results show that the distribution of positive nuclei and intensity of staining varies significantly depending on the antibody used, as well as on the microwaving procedure. Antibodies DO-14, DO-13 and SMP-14 have very good characteristics and are available for immunohistochemical analysis of p53 and MDM-2. Our results indicate, that immunohistochemical expression of p53 and MDM-2 is a not stable and unitary phenomenon and from this point of view a single antibody is not sufficient for its determination. Since, characteristics of p53 and MDM-2 molecules can vary from one sample to the next, panel antibodies capable of determining a wide range of wide type and mutant conformations must be used.