Bcl-2, bcl-x, and bax expression in dysembryoplastic neuroepithelial tumors

Background: Bcl-2, bcl-x and bar are regulatory proteins which are variably expressed in brain tissue and are known to be involved in the regulation o f apoptosis; bcl-2 and bcl-x inhibit apoptosis and bar generally promotes a poptosis. This study is a retrospective clinicopathologic and immunohistoch emical review of 18 dysembryoplastic neuroepithelial tumors (DNTs), specifi cally looking for evidence of aberrant expression of apoptosis regulatory p roteins which may promote the survival of one or more of the cellular const ituents of the tumor. Materials and methods: Eighteen patients (11 males) w ith DNTs comprise the study group. Patients at the time of surgery ranged i n age from 2.1 - 52 years (mean 16.1 years). Mean seizure duration prior to surgery was 6.4 years (n = 16 patients). Sixteen patients were alive with markedly reduced or no seizures at a mean postsurgical follow-up interval o f 63 months; 2 patients were lost to follow-up. Results: All tumors were ch aracterized by an admixture of oligodendroglial cells, neurons and astrocyt ic cells, focally arranged against a microcystic background. Coexistent cor tical dysplasia was noted in 14 evaluable cases. Mitotic figures were rarel y noted in 2 tumors. MIB-1 labeling indices ranged from 0 - 0.6 (mean 0.2). Astrocytes which were part of the tumor stained with all three antibodies in all cases. The oligodendroglial-like cells of DNT stained positively for bcl-2 in 2/17 tumors, bcl-x in 10/17 tumors, and bar in 12/17 tumors. The neuronal cell component of the DNT stained positively with bcl-2 in 15/17 t umors, bcl-x in 5/17 tumors, and bar in 8/17 tumors. Conclusion: Aberrant e xpression of apoptosis-associated proteins, similar to what has been previo usly described in gangliogliomas (another epilepsy-related, dysplasia-assoc iated tumor), may play a role in the pathogenesis of DNT.