Extracts of chronic lymphocytic leukemia lymphocytes have a high level of DNA repair activity for O/sup 6/-methylguanine
Extracts of peripheral lymphocytes from six individuals with chronic lymphocytic leukemia (CLL) were assayed for the ability to remove O/sup 6/-methylguanine (O/sup 6/MeGua) from exogenous DNA. The O/sup 6/MeGua-removing activity in CLL lymphocytes, predominantly B cells, was approximately 7-fold higher than in B lymphocytes of normal individuals and about 2-fold higher than in the unstimulated T type cells of normal persons. The activity measured in extracts of lymphocytes from three blood relatives was in the upper range of the normal distribution. Over 80% of the removal of O/sup 6/MeGua was accomplished by the transfer of the methyl group to cysteine moieties of acceptor proteins in a stoichiometric reaction. If one assumes one acceptor group per acceptor protein, the calculated number of acceptor molecules per CLL lymphocyte falls between 91,000 and 220,000. Thus CLL lymphocytes do not show lower O/sup 6/MeGua-removing activity, in contrast to many tumor cell strains or transformed cell lines, which are reported to have a deficient methyl excision repair phenotype (Mer/sup -/). Instead, the CLL lymphocytes act as if they have a super-Mer/sup +/ phenotype.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- OSTI ID:
- 5243229
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 79
- Country of Publication:
- United States
- Language:
- English
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DNA
BIOLOGICAL REPAIR
LYMPHOCYTES
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ADDUCTS
GUANINE
LEUKEMIA
MUTAGENESIS
PATIENTS
AMINES
ANIMAL CELLS
AROMATICS
AZAARENES
BIOLOGICAL MATERIALS
BIOLOGICAL RECOVERY
BLOOD
BLOOD CELLS
BODY FLUIDS
CONNECTIVE TISSUE CELLS
DISEASES
HEMIC DISEASES
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
LEUKOCYTES
MATERIALS
NEOPLASMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PURINES
RECOVERY
REPAIR
SOMATIC CELLS
550300* - Cytology
550400 - Genetics