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Expression of p210 bcr/abl increases hematopoietic progenitor cell radiosensitivity
M A Santucci1, P Anklesaria, P Laneuville
1Department of Radiation Oncology, University of Massachusetts Medical Center, Worcester 01655.
Summary
The bcr/abl p210 protein increases radiosensitivity and inhibits DNA repair in cells. This may promote further genetic changes in hematopoietic cells, contributing to leukemia progression.
Area of Science:
- Molecular Biology
- Cancer Genetics
- Cellular DNA Repair
Background:
- Chronic myeloid leukemia (CML) is characterized by the Philadelphia chromosome (Ph1+) and bcr/abl gene rearrangement.
- The transition to blastic crisis in CML often involves additional cytogenetic abnormalities.
- Defective DNA repair is linked to chromosomal instability and increased mutation frequency.
Purpose of the Study:
- To investigate if the bcr/abl protein product (p210) affects DNA repair after gamma-irradiation.
- To understand the molecular events linking initial cytogenetic lesions to the terminal phase of CML.
Main Methods:
- Murine cell lines expressing bcr/abl cDNA were exposed to gamma-irradiation.
- Radiosensitivity was assessed by determining the D0 values.
- Programmed cell death and IL-3 dependency were evaluated in bcr/abl expressing cells.
Main Results:
- Expression of p210 bcr/abl significantly increased radiosensitivity in murine cell lines.
- Increased radiosensitivity persisted even after holding cells post-irradiation, suggesting minimal repair of potentially lethal damage.
- bcr/abl expression abrogated IL-3 dependency and inhibited gamma-irradiation-induced programmed cell death.
Conclusions:
- The bcr/abl p210 protein may amplify DNA damage or inhibit DNA repair.
- These effects could stimulate further cytogenetic alterations in hematopoietic cells.
- This suggests a role for bcr/abl p210 in the progression of CML.