Functional analysis of p53-induced apoptosis in glioma cells

已知P53蛋白不仅在细胞周期调控中发挥重要作用，而且在细胞凋亡中也起着重要作用。在本研究中，我们试图阐明负调控P53诱导的细胞凋亡信号的分子机制。1)为了研究腺病毒介导的P53基因转移对癌细胞中Bcl2蛋白表达的影响，我们将bcl2基因导入不表达Bcl2蛋白的KoTCC-1细胞中。在体内外，转Bcl2基因的细胞对P53诱导的细胞凋亡的抵抗力明显高于亲代细胞和单纯载体转染组。2)将构建在异体质粒中的Hela基因文库导入EBNA-1稳定表达细胞，以补充腺病毒P53诱导的细胞凋亡。从抗凋亡细胞中回收的表达载体的插入片段编码194个氨基酸的多肽，与大肠杆菌核苷二磷酸激酶(NDPK)有显著的同源性。NDPK通过乒乓机制调节核苷库的平衡，催化三磷酸核苷的末端磷酸转移到二磷酸核苷，从而抑制P53表达诱导的细胞凋亡。

It has been known that p53 protein plays an important role in not only cell cycle regulation but also apoptosis. In the present study, we attempted to elucidate molecular mechanisms which negatively regulate p53-induced apoptotic signal. During the period of April, 1991 through March, 1992, we identified the following findings :1)To investigate the effects of the expression of Bcl-2 protein in cancer cells on the apoptosis induced by adenoviral-medicated p53 gene transfer, we transfected the bcl-2 gene into KoTCC-1 cell that does not express the Bcl-2 protein. The Bcl-2-transfected cells exhibited significantly higher resistance to p53-induced apoptosis than did either the parental cell or the vector-only transfected cell both in vitro and in vivo.2)A Hela cDNA library constructed in an episomal plasmid was introduced into EBNA-1 stable expression cells for complementation of the adenoviral p53-induced apoptosis. The cDNA insert of the plasmid which was recovered from the apoptosis-resistant cells encoded a 194 amino acid polypeptide that has significant homology with E.coli nucleoside diphoshate kinase (NDPK). The NDPK is known to catalyze a transfer of the terminal phosphate of triphosphate nucleosides to diphosphate nucleosides by a ping-pong mechanism which regulates balance of nucleoside pool, that may inhibit apoptosis induced by p53 expression.