Kamarajan Pachiyappan, Sun Nian-Kang, Chao Chuck C-K
Tumor Biology Laboratory, Department of Biochemistry, Chang Gung University, Taoyuan, Taiwan 333, Republic of China.
Biochem J. 2003 Nov 15;376(Pt 1):253-60. doi: 10.1042/BJ20030659.
Cisplatin-selected cervix carcinoma HeLa cell lines induced less apoptosis, and weaker activation by cisplatin or Fas-activating antibody, of mitochondrial-associated caspase-9 and death receptor-mediated caspase-8 than did parental cells. Furthermore, less DISC (death-inducing signalling complex) was formed in cisplatin-selected cell lines than in parental cells. Ac-IETD-CHO (acetyl-Ile-Glu-Thr-Asp-aldehyde), which has a certain preference for inhibiting caspase-8, or Fas-antagonistic antibody, significantly inhibited cisplatin-induced apoptosis in both parental and cisplatin-selected HeLa cell lines. These results imply that cell-surface death signalling is inducible by cisplatin; that reduction of this pathway is associated with drug resistance, and that cisplatin-selected cells acquire cross-resistance to cell-surface death signalling. Sequential up-regulation of FLIP (FLICE-like inhibitory protein), but not Bcl-2, Bcl-x(L) or inhibitors of apoptosis protein (IAPs), was observed in resistant cells but not in parental cells. The inhibition of FLIP by FLIP antisense oligonucleotides promotes cisplatin and Fas-antibody-induced apoptosis. However, the modulation of apoptosis by FLIP antisense oligonucleotides in resistant cells is greater than that in parental cells. The presented data reveal that the up-regulation of FLIP may contribute to the suppression of apoptosis and thereby change cells that are resistant to cisplatin and Fas-mediated death signals. The results also show that cancer cells that have undergone long-term chemotherapy and become chemoresistant may change the FLIP level, becoming cross-resistant to death factors such as Fas.
顺铂筛选的宫颈癌HeLa细胞系诱导的凋亡较少，与亲本细胞相比，顺铂或Fas激活抗体对线粒体相关的半胱天冬酶-9和死亡受体介导的半胱天冬酶-8的激活作用较弱。此外，顺铂筛选的细胞系中形成的DISC（死亡诱导信号复合物）比亲本细胞中的少。对抑制半胱天冬酶-8有一定偏好的Ac-IETD-CHO（乙酰基-异亮氨酸-谷氨酸-苏氨酸-天冬氨酸醛）或Fas拮抗抗体，显著抑制了亲本和顺铂筛选的HeLa细胞系中顺铂诱导的凋亡。这些结果表明，顺铂可诱导细胞表面死亡信号；该途径的减弱与耐药性相关，并且顺铂筛选的细胞对细胞表面死亡信号获得了交叉耐药性。在耐药细胞中观察到FLIP（类FADD样白介素-1β转化酶抑制蛋白）的顺序上调，但在亲本细胞中未观察到，而Bcl-2、Bcl-x(L)或凋亡抑制蛋白（IAPs）则未上调。FLIP反义寡核苷酸对FLIP的抑制促进了顺铂和Fas抗体诱导的凋亡。然而，FLIP反义寡核苷酸对耐药细胞凋亡的调节作用大于对亲本细胞的调节作用。所呈现的数据表明，FLIP的上调可能有助于抑制凋亡，从而改变对顺铂和Fas介导的死亡信号具有抗性的细胞。结果还表明，经历长期化疗并产生化疗耐药性的癌细胞可能会改变FLIP水平，从而对Fas等死亡因子产生交叉耐药性。
