Gamma-irradiation enhances transgene expression in leukemic cells

Area of Science:

• Oncology
• Gene Therapy
• Immunotherapy

Background:

• Immunotherapy often involves ex vivo gene transfer into tumor cells.
• Modified cells require irradiation before patient reinjection to prevent growth.

Purpose of the Study:

• To investigate the impact of gamma irradiation on transgene expression in gene-modified leukemic cells.
• To assess the potential of irradiated leukemic cells in gene therapy for acute leukemia.

Main Methods:

• Transfection of human and murine leukemic cell lines and primary acute myeloid leukemia (AML) cells with retroviral or adenoviral vectors carrying reporter genes (beta-galactosidase) or immune-stimulating genes (GM-CSF, CD80).
• Exposure of transduced cells to various doses of gamma irradiation.
• Assessment of transgene expression under different promoters (CMV, SV40).
• Evaluation of oxidative stress effects and inhibition by N-acetyl-L-cysteine.
• In vivo studies involving subcutaneous injection of irradiated leukemic cells in mice.

Main Results:

• Gamma irradiation significantly enhanced transgene expression in leukemic cells, particularly when driven by the CMV promoter.
• The effect of irradiation was linked to reactive oxygen species, as evidenced by inhibition with N-acetyl-L-cysteine.
• Transgene expression was also enhanced in vivo following the injection of irradiated leukemic cells.
• SV40 promoter-driven expression was not enhanced by irradiation.

Conclusions:

• Gamma irradiation can enhance transgene expression in gene-modified leukemic cells, suggesting a potential role in immunotherapy.
• The findings support the feasibility of using irradiated, genetically modified leukemic cells as a vaccine for acute leukemia.
• The mechanism involves oxidative stress, highlighting the importance of promoter choice and cellular response.