Abstract IA22: The role of ATM in tumor and endothelial cells in mediating the response of cancer to radiation therapy

Fibroblasts isolated from patients with ataxia telangiectasia are exquisitely sensitive to ionizing radiation and mice lacking the gene mutated in ataxia telangiectasia (ATM) are sensitive to total-body irradiation. Kinase inhibitors of ATM can sensitize tumor cells to radiation, but these inhibitors may also sensitize normal tissues to radiation toxicity. Endothelial cell damage can contribute to the development of long-term side effects after radiation therapy, but whether endothelial cell death plays an important role in tumor response to radiation therapy has remained unclear. To clarify the role of endothelial cells in the response of cancer to radiation therapy, we employed dual recombinase technology using both FlpO and Cre recombinases to generate primary sarcomas in mice with endothelial cell-specific deletion of Atm. Deletion of Atm in proliferating tumor endothelial cells increased endothelial cell death after radiation therapy and enhanced the response of primary sarcomas to radiation as measured by tumor growth delay. However, deletion of Atm from endothelial cells failed to enhance sarcoma eradication as no difference was observed when a higher radiation dose was utilized with local control as the endpoint. In contrast, deletion of Atm from tumor cells increased sarcoma eradication by radiation therapy. These results demonstrate that tumor cells, rather than endothelial cells, are critical targets that regulate sarcoma eradication by radiation therapy. Interesti...
Source: Molecular Cancer Research - Category: Cancer & Oncology Authors: Tags: Therapies Targeting Checkpoints and Mismatch Repair: Oral Presentations - Invited Abstracts Source Type: research