Figure 2.

ATRIs synergize with BETi to kill melanoma cells. (a) The melanoma PDX model M121218 was initiated by thawing a stock of cryopreserved melanoma tumor cells,³⁰ and injecting the cells subcutaneously into the flank of 10 immunocompromised NOD/SCID/IL2Rγ mice (Taconic). Tumor sizes were measured bi-weekly using an caliper. When the tumors reached 75–100 mm³ 5 mice each were randomized to receive either oral and i.p. vehicle, or oral RVX2135 at 75 mg/kg b.i.d. and i.p. injection of AZ20 (MedChemExpress, Princeton, NJ, USA) at 50 mg/kg q.d. for 5 days a week. (b) Four hours after the last dose, tumors were excised and weighed. (c) A blood sample was drawn from the saphenous vein of all mice before treatment and after 3 weeks of treatment. Plasma was isolated and used to determine the level of the melanoma marker S100B using an ELISA kit from Abcam (Elisa kit from Abnova, Taipei City, Taiwan). (d) Single cells were derived by trypsinization of excised tumors from vehicle-treated or combination-treated mice. The cells were lysed and their nuclei were labeled with 7-AAD. Sub-G1 content (apoptosis) was measured by flow cytometry. (e) Tumor pieces from M121218 PDXs treated with vehicle or the RVX2135/AZ20 combination treatment were subjected to western blot analysis