Coexpression of genes involved in apoptosis in central nervous system neoplasms

Purpose: Apoptosis plays a crucial role in normal development and mediates tumor response to chemotherapy. This study investigated the pattern of apop totic gene expression in brain tumor tissue specimens and cell lines. Materials and Methods: BCL2, BCLXL, BCLXS, and BAX transcripts were amplifi ed using reverse transcriptase polymerase chain reaction in 7 high-grade gl iomas (HGGs), 7 ependymomas, and 6 cell lines (2 glioblastomas, 3 medullobl astomas, and 1 supratentorial-primitive neuroectodermal tumor [PNET]). Immu nohistochemical staining for BCL2, BCLX, BAX, and p53 was performed in 7 pe diatric low-grade gliomas (LGGs) and 7 pediatric HGGs. Results: Six of seven gliomas, all ependymomas, and all glioblastoma and me dulloblastoma cell lines expressed BCLXL and BAX. BCL2 expression was only detected in the supratentorial PNET Line PFSK. BCLXS was absent in all tumo rs. By immunohistochemistry, no glial tumors stained positively for BCL2. S imilar BAX and BCLX protein expression was observed in LGG and HGG. Three o f five glioblastomas showed significant p53 expression. Conclusions: Coexpression of proapoptotic and antiapoptotic genes in human brain tumors supports the hypothesis that the relative expression of compet ing genes determines apoptotic threshold.