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HPRT mutations in vivo in human CD 34+ hematopoietic stem cells
B W Grant1, L M Trombley, T C Hunter
1Department of Medicine, Vermont Cancer Center & Genetic Toxicology Laboratory, University of Vermont, Burlington 05405, USA. bgrant@zoo.uvm.edu
Mutation Research
|January 15, 2000
Summary
The T-lymphocyte assay for HPRT mutations accurately reflects mutagenic events in myeloid stem cells. This finding validates the T-lymphocyte assay as a reliable biomarker for myeloid lineage mutations.
Area of Science:
- Biomarkers and Toxicology
- Cancer Research
- Hematology
Background:
- Hypoxanthine-guanine phosphoribosyltransferase (HPRT) mutations in T lymphocytes serve as biomarkers for environmental exposures.
- HPRT mutations share molecular similarities with oncogene mutations in cancers.
- The applicability of T-lymphocyte HPRT mutation assays to tissues with high malignancy rates, like myeloid stem cells, was previously undetermined.
Purpose of the Study:
- To investigate the utility of the HPRT gene assay in detecting mutations within myeloid stem cells, a key progenitor cell type for leukemias.
- To assess the correlation between HPRT mutation frequencies in T lymphocytes and myeloid stem cells within the same individuals.
- To determine if the T-lymphocyte HPRT mutation assay can serve as a surrogate for assessing mutagenic events in the myeloid lineage.
Main Methods:
- Development and application of an HPRT mutation detection assay in human myeloid stem cells.
- Analysis of HPRT mutant frequencies in relation to age and chemotherapy history.
- DNA sequence analysis to confirm mutations in HPRT from myeloid cells.
- Comparative analysis of HPRT mutant frequencies in T lymphocytes (T-MF) and myeloid stem cells (M-MF) from the same patients.
Main Results:
- The myeloid stem cell HPRT assay demonstrated an age-related increase in mutations.
- Chemotherapy patients exhibited elevated mutant frequencies (M-MF) in myeloid stem cells.
- Myelodysplastic syndrome patients showed increased M-MF, as expected, and unexpectedly elevated T-lymphocyte mutant frequencies (T-MF).
- A strong positive correlation was observed between M-MF and T-MF in individual patients.
Conclusions:
- The HPRT gene assay is effective for detecting mutations in myeloid stem cells.
- The T-lymphocyte HPRT mutation assay appears to accurately reflect mutagenic events occurring in the myeloid lineage.
- The T-lymphocyte assay offers a technically simpler alternative for monitoring myeloid mutagenicity compared to the myeloid stem cell assay.