Unique pattern of ET-743 activity in different cellular systems with defined deficiencies in DNA-repair pathways.
The cytotoxic activity of ecteinascidin 743 (ET-743), a natural product derived from the marine tunicate Ecteinascidia turbinata that exhibits potent anti-tumor activity in pre-clinical systems and promising activity in phase I and II clinical trials, was investigated in a number of cell systems with well-defined deficiencies in DNA-repair mechanisms. ET-743 binds to N2 of guanine in the minor groove, but its activity does not appear to be related to DNA-topoisomerase I poisoning as the drug is equally active in wild-type yeast and in yeast with a deletion in the DNA-topoisomerase I gene. Defects in the mismatch repair pathway, usually associated with increased resistance to methylating agents and cisplatin, did not affect the cytotoxic activity of ET-743. However, ET-743 did show decreased activity (from 2- to 8-fold) in nucleotide excision repair (NER)-deficient cell lines compared to NER-proficient cell lines, from either hamsters or humans. Restoration of NER function sensitized cells to ET-743 treatment. The DNA double-strand-break repair pathway was also investigated using human glioblastoma cell lines MO59K and MO59J, respectively, proficient and deficient in DNA-dependent protein kinase (DNA-PK). ET-743 was more effective in cells lacking DNA-PK; moreover, pre-treatment of HCT-116 colon carcinoma cells with wortmannin, a potent inhibitor of DNA-PK, sensitized cells to ET-743. An increase in ET-743 sensitivity was also observed in ataxia telangiectasia-mutated cells. Our data strongly suggest that ET-743 has a unique mechanism of interaction with DNA.
Damia
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Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy. damia@irfmn.mnegri.it
Silvestri
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Carrassa
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Filiberti
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Faircloth
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Liberi
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Foiani
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D'Incalci
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D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D015153:Blotting, Western; D016466:CHO Cells; D002166:Camptothecin / Q000494:pharmacology; D002470:Cell Survival; D006224:Cricetinae; D004247:DNA / Q000378:metabolism; D004260:DNA Repair; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D004149:Dioxoles / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D007546:Isoquinolines / Q000494:pharmacology*; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D044005:Tetrahydroisoquinolines; D000077606:Trabectedin; D014407:Tumor Cells, Cultured; D000077191:Wortmannin
D000730:Androstadienes; D018906:Antineoplastic Agents, Alkylating; D004268:DNA-Binding Proteins; D004149:Dioxoles; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D009687:Nuclear Proteins; D044005:Tetrahydroisoquinolines; D004247:DNA; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004264:DNA Topoisomerases, Type I; D000077606:Trabectedin; D002166:Camptothecin; D000077191:Wortmannin