Abstract 302: High throughput drug screening with engineered tumor spheroids

Abstract

Abstract Physiologically relevant, in vitro cell-based models are important tools to identify effective anticancer drugs. Three-dimensional (3D) clusters of cancer cells, called tumor spheroids, mimic key characteristics of avascular tumors such as diffusion limitations and hypoxia, and hence serve as a relevant model for compound screening. Nevertheless, current spheroid formation techniques face difficulties to generate large number of uniform sized spheroids, conveniently maintain them in culture and biochemically analyze them using commercially available tools. To address this need, we developed a robotic, high throughput technology for three-dimensional culture of cancer cells that is simple to implement, produces consistent size spheroids in standard microwell plates, and allows convenient robotic media exchange and drug addition, and analysis of cellular responses using microplate readers. The technology is based on the use of an aqueous two-phase system. Cancer cells confined in a drop of the denser aqueous phase are robotically dispensed into a microwell containing the immersion aqueous phase. Cells remain within the drop at the bottom of the microwell and form a viable spheroid. We demonstrate the robust performance of this technology by evaluating the effect of two clinically used drugs against biologically aggressive skin cancer and triple negative breast cancer (TNBC) cells. Skin cancer spheroids treated with paclitaxel and cisplatin show dose-dependent decrease in cell viability, but with a greater resistance compared to the monolayer culture (2D) of cells (paclitaxel: LD50,3D = 178.5 nM, LD50,2D = 22.1 nM and cisplatin: LD50,3D = 131.7 μM and LD50,2D = 29.2 μM. TNBC cell monolayer and spheroids treated with cisplatin displayed a similar LD50 value of ∼13.1 μM. However, unlike the monolayer culture of TNBC cells that showed a dose-response to paclitaxel with LD50,2D = 8.0 nM, TNBC spheroids showed resistance to this drug, even at micromolar-scale concentrations, and maintained a high viability. In conclusion, our tumor spheroid technology enables quick and efficient generation of relevant tumor models in standard microplates to conveniently treat with chemical compounds and analyze. This technology allows investigating the efficacy of drug compounds against cancer cells and reveals cellular responses not captured with widely-used monolayer cultures. The ease of conducting and analyzing high throughput experiments will substantially reduce labor and cost, and expedite discovery of effective anti-cancer compounds with a physiologic tumor model. Citation Format: Stephanie Lemmo, Ehsan Aefi, Gary Luker, Hossein Tavana. High throughput drug screening with engineered tumor spheroids. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 302. doi:10.1158/1538-7445.AM2015-302