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. 2018 Sep 4;53(5):1953–1966. doi: 10.3892/ijo.2018.4552

Figure 1.

Figure 1

Comparisons of ATP release, P2Y2R activity and invasiveness between breast cancer cells and RT-R breast cancer cells. (A) ATP released into the extracellular medium was measured using the ENLITEN ATP assay system kit, as described in the Materials and methods. The values represent the means ± SEM of 3 independent experiments (H, HEPES buffer only). **P<0.01, compared to the control (CTRL) of each parent breast cancer cell; ##P<0.01, compared to the CTRL of each RT-R breast cancer cells. (B) [Ca2+]i levels were determined in breast cancer cells and RT-R breast cancer cells to measure P2Y2R activities. Arrows indicate the points at which ATP (10 µM) was added. The values represent the means ± SEM from 3 independent determinations. *P<0.05 and **P<0.01, compared to the CTRL of MDA-MB-231 cells. (C) RT-R-breast cancer cells were treated with ATP for 6 h, and Matrigel invasion assay was performed as described in the Materials and methods. The values represent the means ± SEM of 3 independent experiments. **P<0.01, compared to the CTRL of RT-R-MDA-MB-231 cells; ##P<0.01, compared to ATP-treated RT-R-MDA-MB-231 cells. Scale bar, 50 µm. ATP, adenosine triphosphate; RT-R, radiotherapy-resistant.