Assay Development and Screening
The 4th Dimension: Exploring the temporal effect of chemotherapeutic regimens in physiologically relevant 3D solid primary tumor and metastatic models.
Wednesday, February 7
10:00 AM - 10:30 AM
The wide use of 2D monolayer cultures for cancer drug discovery reflects the technical ease of implementation for drug screening, and the view that oncogenes or tumor suppressor genes are the key genetic drivers of cancer cell proliferation, and therefore, inhibiting these tumor driver genes with drugs should prevent tumor growth. However, there is now ample evidence that the cellular and physiological context in which these oncogenic events occur play a key role in how they drive tumor growth in vivo, and therefore, in how a tumor responds to drug treatments. In vitro three dimensional (3D) spheroid cell culture tumor models are being developed to potentially enhance the predictability and efficiency of drug discovery in cancer. Furthermore, the insight that primary tumors are vastly different from their metastatic counterparts has necessitated a paradigm shift in the development of HTS screening models to efficiently recapitulate key components of primary and metastatic disease. Here we describe the development of an HTS compatible 3D single and multi-cell type tumor spheroid based assay screening platform representing primary disease using libraries of small molecule inhibitors, genome editing and gene silencing reagents (RNAi/CRISPR). One such platform developed as described here generates one spheroid per well with a size of approximately 400µM. The real time study of the effect of chemotherapeutic agents on proliferation and morphology of 3D spheroids adds a temporal component, “time” as the fourth dimension which we hope will better replicate pharmacological effects observed in tumors in vivo, including onset and duration of efficacy and resistance. A modification of this screening platform to accurately represent the metastatic niche is also described. This platform was developed with the objective of finding modulators that are differentially active in 2D vs 3D conditions over time in preventing metastasis and invasion. The ability to increase the throughout for a 3D spheroid assays will enable the generation of pharmacological profiles of chemotherapeutic agents and will hopefully illustrate more effective therapies that might have been missed in 2D, and deprioritize treatments options that might have looked very potent in 2D but have not efficacy in 3D. This approach to cell biology has the potential to improve the physiological relevance of cell-based assays and advance the quantitative modeling of biological systems from cells to organisms.