Document Detail

Effect of human cell malignancy on activity of DNA polymerase iota.
MedLine Citation:
PMID:  20673215     Owner:  NLM     Status:  MEDLINE    
An increased level of mutagenesis, partially caused by imbalanced activities of error prone DNA polymerases, is a key symptom of cell malignancy. To clarify the possible role of incorrect DNA polymerase iota (Pol iota) function in increased frequency of mutations in mammalian cells, the activity of this enzyme in extracts of cells of different mouse organs and human eye (melanoma) and eyelid (basal-cell skin carcinoma) tumor cells was studied. Both Mg2+, considered as the main activator of the enzyme reaction of in vivo DNA replication, and Mn2+, that activates homogeneous Pol iota preparations in experiments in vitro more efficiently compared to all other bivalent cations, were used as cofactors of the DNA polymerase reaction in these experiments. In the presence of Mg2+, the enzyme was active only in cell extracts of mouse testicles and brain, whereas in the presence of Mn2+ the activity of Pol iota was found in all studied normal mouse organs. It was found that in cell extracts of both types of malignant tumors (basal-cell carcinoma and melanoma) Pol iota activity was observed in the presence of either Mn2+ or Mg2+. Manganese ions activated Pol iota in both cases, though to a different extent. In the presence of Mn2+ the Pol iota activity in the basal-cell carcinoma exceeded 2.5-fold that in control cells (benign tumors from the same eyelid region). In extracts of melanoma cells in the presence of either cation, the level of the enzyme activity was approximately equal to that in extracts of cells of surrounding tumor-free tissues as well as in eyes removed after traumas. The distinctive feature of tissue malignancy (in basal-cell carcinoma and in melanoma) was the change in DNA synthesis revealed as Mn2+-activated continuation of DNA synthesis after incorrect incorporation of dG opposite dT in the template by Pol iota. Among cell extracts of different normal mouse organs, only those of testicles exhibited a similar feature. This similarity can be explained by cell division blocking that occurs in all normal cells except in testicles and in malignant cells.
A A Kazakov; E E Grishina; V Z Tarantul; L V Gening
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biochemistry. Biokhimii͡a     Volume:  75     ISSN:  1608-3040     ISO Abbreviation:  Biochemistry Mosc.     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-08-02     Completed Date:  2010-11-04     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376536     Medline TA:  Biochemistry (Mosc)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  905-11     Citation Subset:  IM    
Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia.
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MeSH Terms
Carcinoma, Basal Cell / enzymology*,  genetics
Cell Line, Tumor
DNA-Directed DNA Polymerase / genetics,  metabolism*
Enzyme Activation / drug effects
Enzyme Activators / pharmacology
Eye Neoplasms / enzymology*,  genetics
Lymphoma, B-Cell, Marginal Zone / enzymology*,  genetics
Magnesium / pharmacology
Manganese / pharmacology
Melanoma / enzymology*,  genetics
Mice, Inbred C57BL
Reg. No./Substance:
0/Enzyme Activators; 7439-95-4/Magnesium; 7439-96-5/Manganese; EC 2.7.7.-/DNA polymerase iota; EC DNA Polymerase

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