Targeting of Gli1 or Myc each inhibits cell viability and spheroid formation in NC;P+/+ mesothelioma cells. (A) Early passage NC;P−/− and NC;P+/+ peritoneal mesothelioma cell lines were seeded in 96-well plates (2,500 cells/well) and treated with indicated concentrations of GANT61 or JQ1 for 72 h in medium supplemented with 2.5% FBS for GANT61 treatment and 10% FBS for JQ1. MTS assays show significant decreases in cell viability in NC;P+/+ cells compared to NC;P−/− cells at increasing concentrations of GANT61 and JQ1. IC50 values for the two NC;P+/+ cell lines were determined using GraphPad Prism. IC50’s were not determined for the NC;P−/− cell lines, as these cells were very insensitive to GANT61 and JQ1 due to their low expression of Gli1 and Myc, respectively. (B) Morphological appearance of spheroids in presence or absence of GANT61 and JQ1. NC;P−/− and NC;P+/+ cells were seeded in 6-well plates (5,000 cells/well) in stem cell medium and treated with GANT61 (2.5 and 5 μM) or JQ1 (39 and 78 nM), and cells were photographed after 10 d. Both GANT61 (at 5 μM) and JQ1 (both at 39 and 78 nM) markedly inhibited spheroid formation in NC;P+/+ cells compared to cells cultured in medium containing vehicle (DMSO). In contrast, neither drug had much effect on NC;P−/− cells. (C) Semi-quantitative PCR analysis was performed on NC;P+/+ cell lines treated as above, and after treatment with drugs for 72 h. RNA was extracted with TRIzol and semi-quantitative PCR was performed. (D) Immunoblot analysis of NC;P+/+ cells treated with different concentrations of JQ1. Cells were seeded in 6-well plates, treated with JQ1 for 72 h, lysed, and subjected to immunoblot analysis, which demonstrates inhibition of Myc expression by the drug treatment.