Fig. 1.

Radiation therapy (RT) enhances the membrane expression of CD73 and increases adenosine levels in subcutaneous (sc) LuM-1 tumors. a Cultured LuM-1 cells were treated with or without 10 Gy RT using the MX-160 Labo (mediXtec), and incubated for an additional 24 h. The cells were stained with mAbs to CD39 (left) or CD73 (right) and mean fluorescein intensities (MFI) in the 7AAD (−) live cell population were examined by FACS. Data show a representative FACS profile in 5 different experiments. b Two fractions of 4 Gy RT were delivered selectively to sc tumors of LuM-1 with the remainder of Balb/c mice shielded by a lead plate. Two days later, tumors were resected and single cell suspensions obtained using a Tumor Dissociation Kit (Miltenyi Biotec). The cells were stained with mAbs to CD73 and CD45, and MFI for CD73 were analyzed in live tumor cells defined by 7AAD (−) CD45(−) gated area. P value was calculated with one-way ANOVA followed by Tukey test. c Two fractions of 4 Gy RT were delivered to sc tumors as described above, which were removed at 12, 24 and 48 h after RT. Levels of AMP (adenosine monophosphate), adenosine, and inosine levels in those samples were measured with the LC-MS system (Shimadzu Corp) as described in material and methods. The Y axis shows the height ratio between the 2-morpholino-ethanesulfonic acid (2-ME) as an internal standard and the target molecules. P value was calculated with one-way ANOVA followed by Dunnett’s test and * showed p < 0.05