Prasad S, Soldatenkov V A, Srinivasarao G, Dritschilo A
Department of Radiation Medicine, Division of Radiation Research, Georgetown University Medical Center, The Research Bldg., Room E-204A, Washington, DC 20007-2197, USA.
Int J Oncol. 1998 Oct;13(4):757-64. doi: 10.3892/ijo.13.4.757.
Induction of apoptosis in the estrogen-receptor negative MDA-MB-468 breast tumor cells has been demonstrated by treatments with cytotoxic agents and growth factors. Using these breast tumor cells, we studied ionizing radiation-induced apoptosis. 2D-PAGE of apoptotic cells indicated keratins 18, 19 and heat-shock protein 90 as candidate substrates of apoptosis-associated proteolysis. At the same time, a motif search revealed possible cleavage-sites in keratins 18, 19 (VEVD) and hsp-90 (DEED) that would yield polypeptides of molecular sizes observed experimentally by immunoblotting with specific antisera. This study provides evidence that the insoluble network of intermediate filament proteins of epithelial cells (keratins), and the associated proteins (heat-shock protein 90) constitute targets of caspase-mediated proteolysis during apoptosis triggered by ionizing radiation.
细胞毒性药物和生长因子处理已证实可诱导雌激素受体阴性的MDA-MB-468乳腺肿瘤细胞发生凋亡。利用这些乳腺肿瘤细胞，我们研究了电离辐射诱导的凋亡。对凋亡细胞进行二维聚丙烯酰胺凝胶电泳显示，角蛋白18、19和热休克蛋白90是凋亡相关蛋白水解的候选底物。同时，基序搜索揭示了角蛋白18、19（VEVD）和热休克蛋白90（DEED）中可能的切割位点，这些位点会产生通过用特异性抗血清进行免疫印迹实验观察到的分子大小的多肽。本研究提供了证据，表明上皮细胞中间丝蛋白（角蛋白）的不溶性网络以及相关蛋白（热休克蛋白90）在电离辐射触发的凋亡过程中构成了半胱天冬酶介导的蛋白水解的靶点。
