Towards optimized breast cancer 3D spheroid mono-and co-culture models for pharmacological research and screening

Abstract

BACKGROUND: Reproducibility and physiological relevance are essential features for test systems used in preclinical cancer drug development. In this context, 3D cell culture models like spheroids or organoids have recently become attractive due to their potential of mimicking native biology. Further, to increase screening throughput and effectiveness, full automation of sample preparation and data analysis is important. OBJECTIVE: This work addressed methodological factors of spheroid cell culturing that are of particular relevance for reproducibility and physiological significance in studies investigating metabolic effects of drug treatment, including media composition, extracellular matrix, addition of stromal cells, and the quality of contrast-based readouts. METHODS: Using standardized and enriched media as well as additional basal membrane extract, spheroids were made from MCF10A human breast epithelial cells and MDA-MB-231 human breast cancer cells. In addition, co-culture spheroids of MDA-MB-231 with CCD-1137Sk human fibroblast cells were prepared. Samples were compared in terms of metabolic behaviour. Spheroid analysis employed SpheroidSizer software, confocal microscopy, and Western blotting. RESULTS: Media composition, supportive additives and the co-culture situation can massively alter the growth and metabolic behaviour of spheroids. In particular, spheroid integrity was affected by the presence of extracellular matrix components and upon long-term culturing. Due to drug-or culture-induced spheroid disintegration, automated spheroid size analysis data needed careful evaluation. CONCLUSION: Media composition, extracellular matrix, addition of stromal cells, and automated readouts are important parameters for standardized spheroid-based drug screening approaches. Contrast-based spheroid size analyses in automated high-throughput screenings need special attention, since spheroid-disaggregation or proliferation of surrounding cells may sophisticate the readouts.