Downregulation of Bcl-2 sensitises interferon-resistant renal cancer cells to Fas.
Interferon alpha (IFNalpha) is used to treat patients with advanced renal cell carcinoma (RCC) despite limited clinical benefit. IFNalpha can induce Fas receptor-mediated apoptosis by direct activation of pro-caspase-8 followed by activation of caspase-3. Alternative, indirect activation of caspase-3 via mitochondrial release of cytochrome c can occur and may explain the rescue from Fas-activated cell death by the antiapoptotic members of the Bcl-2 family. In this study, we examined G3139, a novel antisense compound targeting Bcl-2, in combination with IFNalpha. Human RCC lines (SK-RC-44 and SK-RC-07) were treated with IFNalpha, G3139 or a combination of the two. Fas-mediated cytotoxicity was induced by anti-Fas mAb, CH11. An analysis of Bcl-2, Fas and the cleavage of PARP was performed. IFNalpha induced Fas and Bcl-2 in SK-RC-44 and SK-RC-07. IFNalpha sensitised SK-RC-44 to anti-Fas and induced PARP cleavage confirming that IFNalpha has a cytotoxic effect on RCC lines by induction of the Fas antigen. Cytotoxicity was not evident in SK-RC-07 cells treated with IFNalpha. G3139 induced a specific downregulation of Bcl-2 in SK-RC-07 cells, which were then sensitised to anti-Fas after treatment with IFNalpha. Taken together, these results suggest that Fas-dependent pathways as well as alternative pathways, which can be inhibited by Bcl-2, exist in renal cell carcinoma. G3139 in combination with IFNalpha is a potential therapy in patients with metastatic renal cell carcinoma.
Kelly
J D
JD
Department of Oncology, Cambridge University, Box 193, Addenbrookes Hospital, Cambridge CB2 2QQ, UK. jk334@cam.ac.uk
Dai
J
J
Eschwege
P
P
Goldberg
J S
JS
Duggan
B P
BP
Williamson
K E
KE
Bander
N H
NH
Nanus
D M
DM
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002292:Carcinoma, Renal Cell / Q000378:metabolism / Q000473:pathology*; D015536:Down-Regulation; D006801:Humans; D016898:Interferon-alpha / Q000494:pharmacology*; D007680:Kidney Neoplasms / Q000378:metabolism / Q000473:pathology*; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis* / Q000235:genetics; D013873:Thionucleotides / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D019014:fas Receptor / Q000494:pharmacology*
D000970:Antineoplastic Agents; D016898:Interferon-alpha; D016376:Oligonucleotides, Antisense; D019253:Proto-Oncogene Proteins c-bcl-2; D013873:Thionucleotides; D019014:fas Receptor; C408162:oblimersen