Depletion of mammalian O sup 6 -alkylguanine-DNA alkyltransferase activity by O sup 6 -benzylguanine provides a means to evaluate the role of this protein in protection against carcinogenic and therapeutic alkylating agents

Journal Article · Sun Jul 01 04:00:00 EDT 1990 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.87.14.5368· OSTI ID:6262429

Dolan, M E; Pegg, A E ^[1]; Moschel, R ^[2]

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1. Pennsylvania State Univ. College of Medicine, Hershey (USA)
2. National Cancer Institute-Frederick Cancer Research and Development Center, MD (USA)

O{sup 6}-Alkylguanine-DNA alkyltransferase was rapidly and irreversibly inactivated by exposure to O{sup 6}-benzylguanine or the p-chlorobenzyl and p-methylbenzyl analogues. This inactivation was much more rapid than with O{sup 6}-methylguanine: incubation with 2.5 {mu}M O{sup 6}-benzylguanine led to more than a 90% loss of activity within 10 min, whereas 0.2 mM O{sup 6}-methylguanine for 60 min was required for the same reduction. O{sup 6}-Benzylguanine was highly effective in depleting the alkyltransferase activity of cultured human colon tumor (HT29) cells. Complete loss of activity was produced within 15 min after addition of O{sup 6}-benzylguanine to the culture medium and a maximal effect was obtained with 5 {mu}M. In contrast, at least 100 {mu}M O{sup 6}-methylguanine for 4 hr was needed to get a maximal effect, and this reduced the alkyltransferase by only 80%. Pretreatment of HT29 cells with 10 {mu}M O{sup 6}-benzylguanine for 2 hr led to a dramatic increase in the cytotoxicity produced by the chemotherapeutic agents 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU) or 2-chloroethyl(methylsulfonyl)methanesulfonate (Clomesone). Administration of O{sup 6}-benzylguanine to mice at a dose of 10 mg/kg reduced alkyltransferase levels by more than 95% in both liver and kidney. These results indicate that depletion of the alkyltransferase by O{sup 6}-benzylguanine may be used to investigate the role of the DNA repair protein in carcinogenesis and mutagensis and that this treatment may be valuable to increase the chemotherapeutic effectiveness of chloroethylating agents.

• OSTI ID: 6262429
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA) Vol. 87:14; ISSN PNASA; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

550201 -- Biochemistry-- Tracer Techniques
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
ALKYLATED AROMATICS
ALKYLATING AGENTS
AMINES
ANIMALS
AROMATICS
AZAARENES
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY
CARBONIC ACID DERIVATIVES
CARCINOGENESIS
CARCINOMAS
CHEMOTHERAPY
DIGESTIVE SYSTEM
DISEASES
DNA ADDUCTS
DNA REPAIR
EMS
ENZYME ACTIVITY
ENZYMES
ESTERS
GLANDS
GUANINE
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INACTIVATION
ISOTOPE APPLICATIONS
KIDNEYS
LIVER
MAGNETIC RESONANCE
MAMMALS
METHYL NITROSOUREA
MICE
MOLECULAR BIOLOGY
MUTAGENESIS
MUTAGENS
NEOPLASMS
NITROSO COMPOUNDS
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PATHOGENESIS
PURINES
RECOVERY
REPAIR
RESONANCE
RODENTS
SULFONIC ACID ESTERS
THERAPY
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS
VERTEBRATES