Chemotherapy triggers apoptosis in a caspase-8-dependent and mitochondria-controlled manner in the non-small cell lung cancer cell line NCI-H460.
Chemotherapy-induced apoptosis is generally thought to be dependent on a pathway headed by caspase-9. This model is primarily based on studies performed in leukemia cells; however, little is known about caspase cascades in relatively resistant solid tumor cells, including non-small cell lung cancer (NSCLC) cells. Using the NSCLC cell line NCI-H460 (H460), here, we studied the effect of stable expression of various caspase inhibitors on apoptosis induced by the anticancer drugs cisplatin, topotecan, and gemcitabine. Interestingly, overexpression of caspase-9S and X-linked inhibitor of apoptosis (XIAP), both able to inhibit caspase-9 activity, failed to block apoptosis. In contrast, stable expression of caspase-8 inhibitors, such as cytokine response modifier A (CrmA) and dominant-negative caspase-8, almost completely abrogated apoptosis and also enhanced clonogenic survival. Caspase-8 activation in H460 cells was not mediated by death receptors, inasmuch as overexpression of dominant-negative Fas-associated death domain (FADD-DN) did not prevent procaspase-8 cleavage and subsequent apoptosis. However, stable expression of Bcl-2 and Bcl-xL did suppress these apoptotic events, including the release of cytochrome c from mitochondria, which was observed in drug-treated H460 cells. In the NSCLC cell line H460, we, thus, provide evidence for the existence of a novel drug-inducible apoptotic pathway in which activation of caspase-8, and not of caspase-9, forms the apical and mitochondria-dependent step that subsequently activates the downstream caspases.
Ferreira
C G
CG
Department of Medical Oncology, Academic Hospital Vrije Universiteit Amsterdam, The Netherlands.
Span
S W
SW
Peters
G J
GJ
Kruyt
F A
FA
Giaccone
G
G
D048868:Adaptor Proteins, Signal Transducing; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000201:enzymology*; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002945:Cisplatin / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D053200:Fas-Associated Death Domain Protein; D005799:Genes, Dominant; D006801:Humans; D020128:Inhibitory Concentration 50; D019169:Jurkat Cells; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology*; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D019772:Topotecan / Q000494:pharmacology; D014162:Transfection; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein; D000093542:Gemcitabine
D048868:Adaptor Proteins, Signal Transducing; D000590:Amino Acid Chloromethyl Ketones; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; C494811:BCL2L1 protein, human; D002352:Carrier Proteins; D061945:Caspase Inhibitors; D003574:Cytochrome c Group; D018076:DNA, Complementary; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D003841:Deoxycytidine; D019772:Topotecan; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases; D002945:Cisplatin; D000093542:Gemcitabine