Effect of α-difluoromethylornithine on L-phenylalanine mustard-induced cytotoxicity and DNA interstrand cross-linking in a human cell line in vitro

Jonathan M Ducore, L. McNamara

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

We compared L-phenylalanine mustard (L-PAM)-induced cytotoxicity and DNA cross-linking with and without a 42-h preincubation with the ornithine decarboxylase inhibitor α-difluoromethylornithine (DFMO, 1 mM) in a human lymphoma cell line. The combination showed increased toxicity with a D0 ratio of 1.6. L-PAM-induced DNA protein cross-linking as measured by alkaline elution was not altered by a DFMO pretreatment. DNA interstrand cross-linking was increased when L-PAM-treated cells were pretreated with DFMO. The differences occurred between 12 and 24 h following the L-PAM treatment. Peak protein cross-linking occurred 6 h following L-PAM removal with or without DFMO pretreatment. While peak interstrand cross-linking occurred 6 h following L-PAM removal, the DFMO-pretreated cells maintained higher cross-link levels longer than did control cells. The increase in interstrand cross-linking seen in DFMO-pretreated cells was maintained at several different L-PAM doses. The increased cytotoxicity could not be accounted for by the increased cross-linking alone. We have postulated that DFMO pretreatment results in a delay in the appearance of a cross-link removal system. The differences seen between results using these human cells and previous reports using rodent cells are discussed.

Original languageEnglish (US)
Pages (from-to)1068-1072
Number of pages5
JournalCancer Research
Volume46
Issue number3
StatePublished - 1986
Externally publishedYes

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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