HPRT mutations in vivo in human CD 34+ hematopoietic stem cells.
The HPRT mutations in T lymphocytes are widely utilized as biomarkers of environmental exposure and effect. The HPRT gene detects a wide variety of mutation types, many of which are similar at the molecular level to those found in oncogenes in cancers. However, it remains to be determined whether the assay for mutations in T lymphocytes is reflective of mutagenic events in tissues or cells which have high frequencies of malignancy in humans. We now demonstrate that the HPRT gene can be utilized to detect mutations in myeloid stem cells, which are frequent progenitor cells of leukemias. This myeloid stem cell assay shows an age related increase in mutation at HPRT and also detects increases in mutant frequency (M-MF) in patients who have undergone chemotherapy. The myeloid mutants are confirmed to have mutations in the HPRT gene by DNA sequence analysis. Increases in M-MF are seen as expected in the clonally unstable myeloid stem cells of patients with myelodysplastic syndromes; however, unexpectedly these patients also have elevated T-lymphocyte mutant frequencies (T-MF). A good correlation is shown between M-MFs and T-MFs in the same patients. Thus, it appears that the T-lymphocyte assay, which is technically much less demanding than the myeloid assay, appears to faithfully represent the frequency of mutagenic events in the myeloid lineage.
Grant
B W
BW
Department of Medicine, Vermont Cancer Center & Genetic Toxicology Laboratory, University of Vermont, Burlington 05405, USA. bgrant@zoo.uvm.edu
Trombley
L M
LM
Hunter
T C
TC
Nicklas
J A
JA
O'Neill
J P
JP
Albertini
R J
RJ
D000328:Adult; D000368:Aged; D018952:Antigens, CD34 / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001853:Bone Marrow / Q000187:drug effects / Q000502:physiology; D004252:DNA Mutational Analysis / Q000379:methods; D005312:Fetal Blood / Q000187:drug effects / Q000502:physiology; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000187:drug effects / Q000235:genetics*; D007231:Infant, Newborn; D007951:Leukemia, Myeloid / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D008214:Lymphocytes / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D009154:Mutation; D009190:Myelodysplastic Syndromes / Q000097:blood / Q000188:drug therapy / Q000276:immunology; D011237:Predictive Value of Tests; D012307:Risk Factors; D013866:Thioguanine / Q000633:toxicity
D018952:Antigens, CD34; D000970:Antineoplastic Agents; D007041:Hypoxanthine Phosphoribosyltransferase; D013866:Thioguanine