Adenovirus-mediated E2F-1 gene transfer sensitizes melanoma cells to apoptosis induced by topoisomerase II inhibitors.
Melanoma has proven to be resistant to conventional chemotherapy; however,the mechanism of chemoresistance is still unclear. Recent reports show that the transcription factor, E2F-1, may play a role in mediating cytotoxicity of certain chemotherapeutic agents. We have shown in a previous study that adenovirus-mediated overexpression of E2F-1 can efficiently induce apoptosis in melanoma cells. In the present study, the effect of E2F-1 expression on drug sensitivity of melanoma cells was evaluated. Two human melanoma cell lines, SK-MEL-28 and SK-MEL-2, were treated with drugs (etoposide, Adriamycin, roscovitine, cisplatin, 5-fluorouracil, or cycloheximide), alone or in combination with adenoviral vectors expressing beta-galactosidase (Ad-LacZ) or E2F-1 (Ad-E2F-1) at a multiplicity of infection of 1 in vitro. E2F-1 expression was confirmed by Western blot analysis. Sublethal concentrations of each drug alone or infection with Ad-E2F-1 alone produced <5% apoptosis by 3 days posttreatment. Conversely, cotreatment with Ad-E2F-1 and low concentrations of etoposide or Adriamycin markedly sensitized melanoma cells to apoptotic cell death. A slight enhancement of the cytotoxicity of roscovitine was demonstrated in combination with E2F-1 overexpression, but not to cisplatin, 5-fluorouracil, or cycloheximide. Ad-LacZ infection showed no obvious effects on drug sensitivity. Overexpression of p21 can block apoptosis induced by the combination chemogene therapy of Ad-E2F-1 and topoisomerase II poisons and does not require its proliferating cell nuclear antigen-binding ability. The protein synthesis inhibitor cycloheximide also has a cytotoxicity-protective effect against topoisomerase II inhibitor/E2F-1-induced apoptosis and suggests that new protein synthesis is required for this process. Topoisomerase II inhibitors also cooperated with Ad-E2F-1 to enhance antitumor activity in an in vivo model using xenografts in nude mice. When combined with Adriamycin or etoposide, E2F-1 adenovirus therapy resulted in an 87% or 91% decrease in tumor size, respectively, compared with controls (P < 0.002). Our results show that adenovirus-mediated E2F-1 gene transfer can sensitize melanoma cells to some chemotherapeutic agents, particularly topoisomerase II poisons, in vitro and in vivo. These results suggest a new chemosensitization strategy for melanoma gene therapy.
Dong
Yan Bin
YB
Department of Surgery, University of Louisville, James Graham Brown Cancer Center, Louisville, Kentucky 40202, USA.
Yang
Hai Liang
HL
Elliott
Mary Jane
MJ
McMasters
Kelly M
KM
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D018797:Cell Cycle Proteins; D002945:Cisplatin / Q000494:pharmacology; D003131:Combined Modality Therapy; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins; D004317:Doxorubicin / Q000494:pharmacology; D004357:Drug Synergism; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005047:Etoposide / Q000494:pharmacology; D005472:Fluorouracil / Q000494:pharmacology; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D008297:Male; D008545:Melanoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D011687:Purines / Q000494:pharmacology; D000077546:Roscovitine; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493753:E2F1 protein, human; C493754:E2f1 protein, mouse; D004791:Enzyme Inhibitors; D018809:Proliferating Cell Nuclear Antigen; D011687:Purines; D059005:Topoisomerase II Inhibitors; D014157:Transcription Factors; D000077546:Roscovitine; D005047:Etoposide; D004317:Doxorubicin; D003513:Cycloheximide; D002945:Cisplatin; D005472:Fluorouracil