Cell Viability Assay for Targeted Cancer Therapies

Cells were seeded in 96 well culture plates at a density of 3 to 9 × 10³ cells/well depending on cell line. After overnight incubation the MCF7, BT474, MDA-MB-361, ZR-75-30 and SKBR3 cells were treated with either mock treatment, trastuzumab (Roche) as previously described^{46 (link),47 (link)} or GSK2830371 (Sigma-Aldrich) alone or combined. The HCC1954 cells were treated with either mock treatment, erlotinib (Sigma-Aldrich) as previously described^{48 (link)} or GSK2830371 alone or combined. The drugs were added at a final concentration of 10 μgr/ml, 50 μgr/ml and 100 μgr/ml for trastuzumab; 0.1 μM, 0.5 μM and 1 μM for erlotinib; 1 μM and 2.5 μM for GSK2830371. Cell viability was measured on day 7 using the MTT proliferation assay kit (Promega, Madison, WI, USA) according to manufacturer instructions. The absorbance was measured at 595 nm on the Tecan sunrise microplate reader (Tecan Group Ltd, Mannedorf, Switzerland). The data shown are representative of at least three independent experiments and each treatment was performed in pentaplicate.