Radiation dose-fractionation effects on immune modulation in murine mammary tumors

Radiation therapy (RT) induces pleiotropic effects on the tumor immune microenvironment, but how these changes are modulated by radiation dose-fractionation is not well understood. Our in vivo data murine data suggests that while changes evoked by RT in the tumor immune compartment are largely concordant between radiation regimens, several key immunological processes are differentially regulated by radiation dose-fractionation. Overall design: Wildtype female C57BL/6 mice were injected with AT3-OVA triple negative mammary tumor cells orthotopically into the mammary fat pad and received local RT to the tumors using either the 3x4Gy regimen or the 1x20Gy regimen. Tumors were harvested at days 5 and 13 post completion of RT, processed into single cell suspensions and stained for the pan-leukocyte marker CD45.2. CD45.2+ immune cells were sorted by fluorescence-activated cell sorting (FACS) and underwent RNA extraction. Only samples with an RNA integrity number (RIN) of greater than 8.5 were processed for library preparation. Mock-irradiated tumors from mice anaesthetized as per their irradiated counterparts were used as controls (3x0 Gy and 1x0 Gy, respectively).