Apaf‐1 overexpression partially overcomes apoptotic resistance in a cisplatin‐selected HeLa cell line

FEBS Letters

Chao, Chuck C.-K¹  Sun, Nian-Kang¹  Kamarajan, Pachiyappan¹  Sun, Chun-Ling¹ 

[1] Tumor Biology Laboratory, Department of Biochemistry, Chang Gung University, Taoyuan 33332, Taiwan

关键词: Apoptotic protease activating factor-1;    Apoptosis;    Cisplatin;    Caspase-3;    Cytochrome c;    Apaf-1;    apoptotic protease activating factor-1;    Cisplatin;    cis-diamminedichloroplatinum(II);    PARP;    poly(ADP-ribose) polymerase;    VDAC;    voltage-dependent anion channel;    Ac-DEVD-CHO;    acetyl-Asp-Glu-Val-Asp-aldehyde;    Ac-LEHD-CHO;    acetyl-Leu-Glu-His-Asp-aldehyde;    Ac-IETD-CHO;    acetyl-Ile-Glu-Thr-Asp-aldehyde;   

DOI  :  10.1016/S0014-5793(01)02817-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Inhibition of caspase-3-mediated apoptosis has been hypothesized to be associated with chemoresistance. Investigations of apoptosis revealed that cytosolic cytochrome c is associated with a complex of apoptotic protease activating factor-1 (Apaf-1), an adapter molecule, and caspase-9 to activate caspase-3. However, whether these apoptotic molecules are involved in acquired cisplatin resistance is not understood. The present work shows reduced activation of caspase-3 and apoptosis in a cisplatin-selected HeLa cell line. Ac-DEVD-CHO, a caspase-3 inhibitor, inhibited cisplatin-induced apoptosis about 60–70% in both cell lines. Ac-LEHD-CHO, a caspase-9 inhibitor or Ac-IETD-CHO, a caspase-8 inhibitor, inhibited cisplatin-induced caspase-3 activation and apoptosis similarly in both cell lines. In addition, cisplatin induced the activation of caspase-9, the upstream activator of caspase-3, in a dose-dependent manner, and the activation of caspase-9 was less induced in resistant cells. The accumulation of cytosolic cytochrome c, an activator of caspase-9, and the induction of the mitochondrial membrane-associated voltage-dependent anion channel were also reduced in cisplatin-resistant cells. However, the concentration of Bcl-2 family proteins in cisplatin-resistant cells was normal. The concentration of Apaf-1 was unaltered in both cell lines. Increasing the cellular concentration of Apaf-1 through the transient expression of the gene increased the induction of apoptosis in resistant cells, associated with enhanced activation of caspase-9, caspase-3 and DNA fragmentation factor. Regression analysis reveals that the modification factor, the ratio of the slope in the linear range of the dose–response curve with Apaf-1 to the slope without Apaf-1, is 1.5 and 4.75 in the HeLa and cisplatin-resistant HeLa cells, respectively. These results indicate that apoptosis and caspases are less induced in cisplatin-selected HeLa cells. They also suggest that ectopic overexpression of Apaf-1 may partially reverse the acquired cisplatin resistance.

【 授权许可】

Unknown