December 1, 2016
For pairwise and triple combinations, compound doses were combined at a fixed ratio of 1:1 and 1:1:1, respectively (17). DMSO concentrations were normalized per well. In addition, vehicle (DMSO) and positive controls (staurosporine) were transferred. All treatments were performed in triplicates. One of the replicates received 50 nL of 2 mmol/L CellEvent Caspase-3/7 Green Detection Reagent (Thermo) using a HP D300 dispenser (Tecan). Cells were treated for 72 to 96 hours. Caspase-3/7 activity was imaged every 24 hours. At the end of the treatment, cells were fixed, and their DNA was stained and imaged (18, 19). High-order experiments combining more than 3 drugs were also setup with fixed ratios but only testing 4 dose points. To validate synergies of MDM2 combinations, matrices were tested to assess effects at different ratios of the single agents
Like classical chemotherapy regimens used to treat cancer, targeted therapies will also rely upon polypharmacology, but tools are still lacking to predict which combinations of molecularly targeted drugs may be most efficacious. In this study, we used image-based proliferation and apoptosis assays in colorectal cancer cell lines to systematically investigate the efficacy of combinations of two to six drugs that target critical oncogenic pathways. Drug pairs targeting key signaling pathways resulted in synergies across a broad spectrum of genetic backgrounds but often yielded only cytostatic responses. Enhanced cytotoxicity was observed when additional processes including apoptosis and cell cycle were targeted as part of the combination. In some cases, where cell lines were resistant to paired and tripled drugs, increased expression of antiapoptotic proteins was observed, requiring a fourth-order combination to induce cytotoxicity. Our results illustrate how high-order drug combinations are needed to kill drug-resistant cancer cells, and they also show how systematic drug combination screening together with a molecular understanding of drug responses may help define optimal cocktails to overcome aggressive cancers. Cancer Res; 76(23); 6950-63. Š2016 AACR. Š2016 American Association for Cancer Research.
Horn, T; Ferretti, S; Ebel, N; Tam, A; Ho, S; Harbinski, F; Farsidjani, A; Zubrowski, M; Sellers, WR; Schlegel, R; Porter, D; Morris, E; Wuerthner, J; Jeay, S; Greshock, J; Halilovic, E; Garraway, LA; Caponigro, G; LehĂĄr, J;
Journal: Cancer Res. Pages: 6950-6963