Background: Traditional drug screening strategies have used single layer of cells grown on plastics (monolayer (2D) cell cultures), which is architecturally and biochemically different from the natural physiological environment of cells as they exist in tumors. Cells in a tumor microenvironment exhibit complex cell-to-cell interactions between tumor cells as well as with other cell types (fibroblasts, endothelial cells, inflammatory cells). As these interactions are deficient in 2D cell cultures, testing compounds using such a “minimalistic” approach could result in physiologically irrelevant drug responses and misidentification of compounds which are subsequently less efficacious when tested in animal models. Therefore in vitro screens based on 2D cell cultures have a low predictability and poor translatability to in vivo efficacy thus making them physiologically irrelevant for screening. Recently, based on the recognition that 3D cell cultures are a physiologically-relevant alternative to 2D monolayer cultures, a number of approaches have been used to generate 3D cell culture models for cancer study. These include the use of synthetic scaffolds, microcarrier beads and hanging drop cultures. Methods: In this study we use a levitation system to promote aggregation and growth of tumor cells into multicellular tumor spheroids (MTS) that are amenable for high throughput screening. We have used the system to culture established cancer cell lines, such as (MDA-MB-231, A549, PC-3), as well as primary cells. Since the tumor microenvironment is a critical factor that promotes tumor growth, we have also used the system to develop an in vitro co-culture model in which mammary epithelial tumor cells and fibroblasts grow together to simulate the tumor microenvironment. Fibroblasts are a critical component of the tumor stroma influencing tumor initiation, progression and metastasis. We validate our system using a combination of approaches including immunofluorescence, high content imaging and flow cytometry to demonstrate that our 3D culture model has characteristics of in vivo tumors. Key features that distinguish our system from other currently available 3D systems available are: 1) the dynamic environment wherein the cells aggregate and grow into “mini tumors” mimicking tumors in an in vivo setting; 2) ease of co-culturing the tumors with other cell types; 3) amenability to high throughput screening; 4) “long-lasting” cell viability, facilitating long-term culture; 5) ability to enrich for tumors that have stem-cell like features. We expect that our model will be useful to not only derive physiological responses from compound treatments, but will also have potential applications in studying drug penetration and resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4259. doi:1538-7445.AM2012-4259