p210 BCR/ABL kinase regulates nucleotide excision repair (NER) and resistance to UV radiation

Area of Science:

• Molecular Biology
• Cancer Research
• DNA Repair Mechanisms

Background:

• The BCR/ABL fusion protein, a constitutively active tyrosine kinase, is implicated in various leukemias.
• BCR/ABL is known to confer resistance to DNA damage and genetic instability.
• The role of BCR/ABL in modulating DNA repair pathways, specifically nucleotide excision repair (NER), remains incompletely understood.

Purpose of the Study:

• To investigate the effect of BCR/ABL expression on nucleotide excision repair (NER) activity.
• To determine if BCR/ABL modulates cellular response to ultraviolet (UV) radiation.
• To elucidate the differential impact of BCR/ABL on NER in lymphoid versus myeloid cells.

Main Methods:

• Ectopic expression of p210 BCR/ABL in murine lymphoid BaF3 cells and human/murine myeloid cell lines.
• In vitro assessment of NER activity.
• Evaluation of cellular hypersensitivity/resistance to UV treatment.
• Treatment with the ABL tyrosine kinase inhibitor STI571.
• Analysis of protein-protein interactions, including PCNA and XPB.

Main Results:

• p210 BCR/ABL inhibited NER in lymphoid cells, leading to UV hypersensitivity and a mutator phenotype.
• Conversely, p210 BCR/ABL enhanced NER in myeloid cells, conferring resistance to UV irradiation.
• The tyrosine kinase activity of p210 BCR/ABL was crucial for NER deregulation, as STI571 reversed the observed effects.
• NER hypoactivity in lymphoid cells correlated with decreased PCNA-XPB interaction, while hyperactivity in myeloid cells showed enhanced interaction.
• p190 BCR/ABL did not significantly affect NER in either cell type.

Conclusions:

• p210 BCR/ABL differentially regulates NER activity depending on the cellular context.
• In lymphoid cells, p210 BCR/ABL-mediated inhibition of NER contributes to UV sensitivity and mutagenesis.
• In myeloid cells, p210 BCR/ABL-induced enhancement of NER promotes resistance to UV damage.