Caspase-1α is down-regulated in human ovarian cancer cells and the overexpression of caspase-1α induces apoptosis
Caspase-1α is down-regulated in human ovarian cancer cells and the overexpression of caspase-1α induces apoptosis
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DOI：
10.1158/0008-5472.can-05-0239
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发表时间：
2005-10-01
期刊：
影响因子：
11.2
通讯作者：
Auersperg, N
中科院分区：
文献类型：
--
作者：
Feng, Q;Li, PX;Auersperg, N
Caspase-1在细胞因子的加工和神经元和巨噬细胞的凋亡中起关键作用。目前还不清楚它是否还会导致癌细胞的凋亡。在这项研究中，我们筛选了卵巢癌细胞系及其起源组织卵巢表面上皮(OSE)中一系列与凋亡相关的蛋白。Caspase-1α蛋白在OSE和寿命延长但有限的非致瘤性OSE(永生化OSE)中含量丰富，但在癌细胞系A2780和OVCARIO中减少。Western印迹和免疫荧光检测显示，与OSE相比，8株卵巢癌细胞株中有6株caspase-1α表达水平显著降低。实时逆转录-聚合酶链式反应显示，CASP1基因的稳定转录产物与蛋白质水平成正比。Caspase1α过表达导致显著的细胞凋亡，但过表达无催化活性的Caspase-1α突变体则没有，证实这种作用是caspase-1α特异性的。Caspase-1α和末端核苷酸转移酶介导的dUTP-X缺口末端标记的免疫荧光共定位清楚地建立了细胞凋亡和caspaselot表达之间的联系。在Caspase-Lot过表达的A2780细胞中，caspase-9和caspase-3被激活，提示参与了一种内在的凋亡途径。Caspase-1α过表达并不改变顺铂对A2780和OVCARIO细胞的凋亡作用，提示该药激活了不同的途径。免疫组织化学显示，caspase-1在卵巢浆液性癌中的表达低于OSE。我们的研究首次表明，caspase-1α在卵巢癌细胞中是促凋亡的，并提出了其下调可能是增加癌细胞对凋亡的抵抗力的机制之一。
Caspase-1 plays a key role in the processing of cytokines and in the apoptosis of neurons and macrophages. Whether it also causes apoptosis of cancer cells has been unclear. In this study, we screened an array of apoptosis-related proteins in ovarian carcinoma cell lines and their tissue of origin, ovarian surface epithelium (OSE). Caspase-1 alpha protein was abundant in OSE and in nontumorigenic OSE with extended but limited life spans (immortalized OSE), but was reduced in the cancer lines A2780 and OVCARIO. By Western blot and immunofluorescence, caspase-1 alpha levels were greatly reduced in six of eight ovarian carcinoma lines compared with OSE. By realtime reverse transcription-PCR, steady-state transcripts of the CASP1 gene were proportional to protein levels. Caspase1 alpha overexpression caused significant apoptosis, but overexpression of a caspase-1 alpha mutant without catalytic activity did not, confirming that the effect was caspase-1 alpha-specific. Immunofluorescence of caspase-1 alpha and terminal nucleotidyl transferase-mediated dUTP-X nick end labeling colocalization clearly established a link between apoptosis and caspaselot expression. Caspase-9 and caspase-3 were activated in caspase-lot overexpressing A2780 cells, suggesting involvement of an intrinsic apoptotic pathway. Caspase-1 alpha overexpression did not change the apoptotic effect of cisplatin in A2780 and OVCARIO cells, suggesting that this agent activates a different pathway. Inummohistochernically, caspase-1 was lower in ovarian serous carcinomas than in OSE. Our study indicates, for the first time, that caspase-1 alpha is proapoptotic in ovarian cancer cells, and raises the possibility that its downregulation is one of the mechanisms which increase resistance to apoptosis in cancer cells.