Monitoring humans for somatic mutation in the endogenous pig-a gene using red blood cells

The endogenous X‐linked PIG‐A gene is involved in the synthesis of glycosyl phosphatidyl inositol (GPI) anchors that tether specific protein markers to the exterior of mammalian cell cytoplasmic membranes. Earlier studies in rodent models indicate that Pig‐a mutant red blood cells (RBCs) can be indu...

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Bibliographic Details
Published in:Environmental and molecular mutagenesis 2011-12, Vol.52 (9), p.784-794
Main Authors: Dobrovolsky, Vasily N., Elespuru, Rosalie K., Bigger, C. Anita H., Robison, Timothy W., Heflich, Robert H.
Format: Article
Language:English
Subjects:
Adolescent
Adult
Aged
Antineoplastic Agents - toxicity
Biological and medical sciences
CD59 Antigens - genetics
CD59 surface marker
chemotherapy
clastogen
Erythrocytes - drug effects
Erythrocytes - metabolism
Female
Flow Cytometry
Fundamental and applied biological sciences. Psychology
Genetic Testing - methods
Genetics of eukaryotes. Biological and molecular evolution
glycophorin
glycosyl phosphatidyl inositol anchor
Humans
Male
Medical sciences
Membrane Proteins - genetics
Middle Aged
Mutagens - toxicity
Mutation
Toxicology
Young Adult
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Summary:The endogenous X‐linked PIG‐A gene is involved in the synthesis of glycosyl phosphatidyl inositol (GPI) anchors that tether specific protein markers to the exterior of mammalian cell cytoplasmic membranes. Earlier studies in rodent models indicate that Pig‐a mutant red blood cells (RBCs) can be induced in animals treated with genotoxic agents, and that flow cytometry can be used to identify rare RBCs deficient in the GPI‐anchored protein, CD59, as a marker of Pig‐a gene mutation. We investigated if a similar approach could be used for detecting gene mutation in humans. We first determined the frequency of spontaneous CD59‐deficient RBCs (presumed PIG‐A mutants) in 97 self‐identified healthy volunteers. For most subjects, the frequency of CD59‐deficient RBCs was low (average of 5.1 ± 4.9 × 10−6; median of 3.8 × 10−6 and mutant frequency less than 8 × 10−6 for 75% of subjects), with a statistically significant difference in median mutant frequencies between males and females. PIG‐A RBC mutant frequency displayed poor correlation with the age and no correlation with the smoking status of the subjects. Also, two individuals had markedly increased CD59‐deficient RBC frequencies of ∼300 × 10−6 and ∼100 × 10−6. We then monitored PIG‐A mutation in 10 newly diagnosed cancer patients undergoing chemotherapy with known genotoxic drugs. The frequency of CD59‐deficient RBCs in the blood of the patients was measured before the start of chemotherapy and three times over a period of ∼6 months while on/after chemotherapy. Responses were generally weak, most observations being less than the median mutant frequency for both males and females; the greatest response was an approximate three‐fold increase in the frequency of CD59‐deficient RBCs in one patient treated with a combination of cisplatin and etoposide. These results suggest that the RBC PIG‐A assay can be adopted to measuring somatic cell mutation in humans. Further research is necessary to determine the assay's sensitivity in detecting mutations induced by genotoxic agents acting via different mechanisms. Environ. Mol. Mutagen., 2011. Published 2011 Wiley‐Liss, Inc.
ISSN:0893-6692
1098-2280
DOI:10.1002/em.20667