Products from alkylation of DNA in cells by melphalan: human soft tissue sarcoma cell line RD and Escherichia coli WP2.
Alkylation of DNA was studied after treatment with [3H]melphalan (phenylalanine mustard; 1-2 microM) using a human tumour cell line, RD, in culture, or Escherichia coli (WP2 or WP2-uvrA strains) in growth medium. After 6 h at 37 degrees C, treated cells were isolated and re-suspended in fresh growth media. Samples were taken at times up to 48 h for isolation of DNA, and in some cases also RNA and protein (which were found to be alkylated to about the same extent as DNA). Alkylated DNA was analysed as previously described (M.R. Osborne and P.D. Lawley, Chem.-Biol. Interact 89 (1993) 49-60). The four principal products, mono-7-alkylguanine (G-M-OH); mono-3-alkyladenine (A-M-OH); and the cross-linked products G-M-G and A-M-G, were identified in DNA from melphalan treated cells, and quantitatively determined. In each case, alkylation of cellular macromolecules was maximal after about 6 h. In DNA of the human tumour cell line, the relative amounts of adenine products decreased with time, most markedly with A-M-OH to 42% of the 2-h value after 48 h. In DNA of both bacterial strains, A-M-OH was virtually undetectable even at early times. Comparisons between the time course of relative decreases in amounts of these alkylpurine products and the corresponding values for alkylated DNA in vitro suggest that the adenine products are subject to removal by repair enzyme action in E. coli of either strain.
Osborne
M R
MR
Institute of Cancer Research, Haddow Laboratory, Sutton, Surrey, UK.
Lawley
P D
PD
Crofton-Sleigh
C
C
Warren
W
W
D000478:Alkylation; D001426:Bacterial Proteins / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D018736:DNA Adducts / Q000737:chemistry / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D006801:Humans; D008558:Melphalan / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D011687:Purines / Q000032:analysis / Q000378:metabolism; D012329:RNA, Bacterial / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D012208:Rhabdomyosarcoma / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D001426:Bacterial Proteins; D018736:DNA Adducts; D004269:DNA, Bacterial; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D011687:Purines; D012329:RNA, Bacterial; D012334:RNA, Neoplasm; D008558:Melphalan