作者: Karen M. Henkels , John J. Turchi
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摘要: We have assessed in detail the effect of cisplatin-activated programmed cell death cisplatin-sensitive human ovarian cancer line A2780 and two drug-resistant subclones, CP70 C30. To determine whether differential extent apoptosis observed between sensitive resistant lines was result dissimilar upstream signaling events, we execution apoptotic events that precede target protein proteolysis subsequent chromosomal DNA degradation. Proteolytic degradation procaspase-3 both C30 cells following IC50 cisplatin treatment, whereas no proteolyzed caspase-3 subunits were detected cells. However, using a direct enzymatic assay measuring cleavage synthetic peptide substrate (N-acetyl-Asp-Glu-Val-Asp-p-nitroanilide), activity extracts prepared from treated at IC90 level 2-3-fold less than Because activation by caspase-9 requires release cytochrome c into cytoplasm, determined cytoplasmic each response to treatment. Consistent with data, very small increase dramatic increases evident lines. The expression mitochondrial factors Bcl-2, Bcl-x, Bax because has been implicated regulation or mitochondria. Bcl-2 Bcl-xL proteins remained relatively unchanged for over 48 h after exposure within same time period, decreased CP70- C30-resistant lines, an observed. Expression proapoptotic Bcl-xS only independent A change Mr 24,000 21,000 isoform evidenced treatment and, greater extent, cells, which also expressed 16,000 variant. Evidence alternative pathway obtained demonstrating increased FADD These results support model cisplatin-induced -resistant proceeds via caspase-3-independent -dependent pathways, respectively.