Figure 4.

AM₂ receptor antagonist inhibits in vitro viability of human breast cancer cell line MDA-MB-231 as well as subcutaneous MDA-MB-231 tumor growth in BALB/c nude mice. (a) Daily treatment with small molecule AM₂ receptor antagonists significantly decreased the viability of MDA-MB-231 cells in vitro by 55% after 3 days when treated with 10 μM (±)-25, compared to that of vehicle-treated controls (p < 0.01, unpaired t-test). Data are from three independent experiments and presented as mean ± SD. (b) Mice (n = 10 per group) were inoculated subcutaneously with MDA-MB-231 cells to generate tumors, and first treatment was given on the day of the first tumor volume measurement (arrow). Tumor growth rates were significantly reduced in mice treated daily with 20 mg/kg ip (±)-25 (p < 0.001, simple linear regression comparing the line of best fit). Data are presented as mean ± SD.