518A2 Melanoma cells are protected by G3139 and other antineoplastic agents against the cytotoxic effects of DTIC

Luba Benimetskaya, Paul Miller, C. A. Stein

Research output: Contribution to journalArticle

Abstract

G3139 is an antisense Bcl-2 phosphorothioate oligonucleotide that has been combined with DTIC in a phase III clinical trial in melanoma. However, its actual mechanism of action in melanoma is controversial. Treatment of 518A2 melanoma cells with either G3139 or G4126 (a two-base mismatch) and then with light-activated DTIC caused these cells (but not SK-Mel-30 or 346.1 cells) to be protected against the cytotoxic effects of DTIC. This cytoprotection was not recapitulated with a phosphodiester congener of G3139 nor with a small interfering RNA (siRNA) also targeted to the Bcl-2 mRNA. Administering the drugs in reverse order also did not produce cytoprotection, and an 18-mer phosphorothioate homopolymer of thymidine was also inactive. Subsequently, it was discovered that gemcitibine and cis-platinum also induced cytoprotection to DTIC in this cell line, suggesting that the cytoprotection is a stress response to chemical proapoptotic stress. Cytoprotection was completely inhibited by O6-benzylguanine, an inhibitor of O6-guanosine alkyltransferase (OGAT) activity. However, a direct assay of OGAT activity demonstrated that 518A2 melanoma cells are essentially completely devoid of it, either basally or induced. The cytoprotection may thus be caused by a chemical stress-induced increase in mismatch repair activity.

Original languageEnglish (US)
Pages (from-to)206-214
Number of pages9
JournalOligonucleotides
Volume15
Issue number3
DOIs
StatePublished - 2005

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Dacarbazine
Cytoprotection
Antineoplastic Agents
Melanoma
Alkyl and Aryl Transferases
Guanosine
Phosphorothioate Oligonucleotides
Homopolymerization
Thymidine
Small Interfering RNA
Cisplatin
Assays
Phase III Clinical Trials
DNA Mismatch Repair
Repair
Cells
Messenger RNA
oblimersen
Pharmaceutical Preparations
Light

ASJC Scopus subject areas

  • Genetics
  • Pharmacology

Cite this

518A2 Melanoma cells are protected by G3139 and other antineoplastic agents against the cytotoxic effects of DTIC. / Benimetskaya, Luba; Miller, Paul; Stein, C. A.

In: Oligonucleotides, Vol. 15, No. 3, 2005, p. 206-214.

Research output: Contribution to journalArticle

Benimetskaya, Luba ; Miller, Paul ; Stein, C. A. / 518A2 Melanoma cells are protected by G3139 and other antineoplastic agents against the cytotoxic effects of DTIC. In: Oligonucleotides. 2005 ; Vol. 15, No. 3. pp. 206-214.
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