Expression of apoptotic and proliferation markers in meningiomas.

Fifty-two intracranial, totally excised meningiomas were immunohistochemically analysed for the expression of bcl-2 and p53 proteins, in parallel with the assessment of the proliferating cell nuclear antigen labelling index (PCNA LI) and the mitotic index (MI). bcl-2 was expressed in 26.8 per cent and p53 in 32.6 per cent of the tumours, exhibiting a similar staining pattern, with low levels of immunoreactive cells. The bcl-2-positive/p53-negative subgroup showed a significant association with a benign histological pattern. Expression of bcl-2 appeared to have no influence on the rate of recurrence; p53 expression was the only factor with prognostic significance for recurrence (p = 0.10). There was no interaction between bcl-2 and p53 expression. The PCNA LI was correlated with the MI and the grade of malignancy, proving to be a useful proliferation marker and an additional indicator of the more anaplastic histological patterns in meningiomas. Proliferation indices appeared to have no correlation with the recurrence rate of totally resected tumours. Meningiomas expressing the bcl-2 protein presented a high proportion of proliferating cells in S phase. In contrast, all the tumours which recurred had a minimal S-fraction of proliferating nuclei. These findings may improve our understanding of the interaction between cell proliferation, expression of apoptotic markers, and recurrence in meningiomas.