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6-Methylguanine and 6-methylguanosine Inhibit Colony-forming Ability in a Malignant Xeroderma Pigmentosum Cell Line but Not in Other Xeroderma Pigmentosum and Normal Human Fibroblast Strains After Treatment With...

Overview
Specialty Oncology
Date 1987 Jan 1
PMID 3818780
Citations 1
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Abstract

The XP cell strain XP29MA, its malignant counterpart XP29MAmal and a normal human fibroblast strain were tested for colony-forming ability after treatment with HECNU in the presence of m6G, m6Gua, and he7G. In XP29MAmal, inhibition of post-HECNU colony-forming ability was 35% when 0.25 mM of either m6G or m6Gua were present, whereas in XP29MA and the normal fibroblast strain no inhibition was detected. The he7G caused a similar but smaller inhibitory effect in XP29MAmal, but failed to do so in XP29MA. HECNU predominantly exerts its killing effect by alkylating O-6 of DNA-bound guanine and causing DNA interstrand crosslinks. Alkylation of O-6 of guanine can be repaired by 6-methylguanine-DNA methyltransferase. From our experiments we conclude that in XP29MAmal this methyltransferase was inhibited in the presence of the 6-alkylguanines, thus leaving more 2-chloroethylated sites in DNA unrepaired. This results in sensitization in terms of decreased colony-forming ability observed only in the malignant cell line.

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References
1.
Thielmann H, Edler L, Popanda O, Friemel S . Xeroderma pigmentosum patients from the Federal Republic of Germany: decrease in post-UV colony-forming ability in 30 xeroderma pigmentosum fibroblast strains is quantitatively correlated with a decrease in DNA-incising capacity. J Cancer Res Clin Oncol. 1985; 109(3):227-40. DOI: 10.1007/BF00390362. View

2.
Scudiero D, Meyer S, Clatterbuck B, Mattern M, Ziolkowski C, Day 3rd R . Sensitivity of human cell strains having different abilities to repair O6-methylguanine in DNA to inactivation by alkylating agents including chloroethylnitrosoureas. Cancer Res. 1984; 44(6):2467-74. View

3.
Myrnes B, Eggset G, Volden G, Krokan H . Enzymatic repair of premutagenic DNA lesions in human epidermis. Quantitation of O6-methylguanine-DNA methyltransferase and uracil-DNA glycosylase activities. Mutat Res. 1984; 131(3-4):183-6. DOI: 10.1016/0167-8817(84)90059-2. View

4.
Snow E, Foote R, Mitra S . Replication and demethylation of O6-methylguanine in DNA. Prog Nucleic Acid Res Mol Biol. 1983; 29:99-103. DOI: 10.1016/s0079-6603(08)60434-1. View

5.
Waldstein E, Cao E, Miller M, CRONKITE E, Setlow R . Extracts of chronic lymphocytic leukemia lymphocytes have a high level of DNA repair activity fo O6-methylguanine. Proc Natl Acad Sci U S A. 1982; 79(15):4786-90. PMC: 346763. DOI: 10.1073/pnas.79.15.4786. View