3-D Tumor Model forIn VitroEvaluation of Anticancer Drugs

Abstract

The efficacy of potential anticancer drugs during preclinical development is generally tested in vitro using cancer cells grown in monolayer; however, a significant discrepancy in their efficacy is observed when these drugs are evaluated in vivo. This discrepancy, in part, could be due to the three-dimensional (3-D) nature of tumors as compared to the two-dimensional (2-D) nature of monolayer cultures. Therefore, there is a need for an in vitro model that would mimic the 3-D nature of tumors. With this objective, we have developed surface-engineered, large and porous biodegradable polymeric microparticles as a scaffold for 3-D growth of cancer cells. Using the MCF-7 cell line as model breast cancer cells, we evaluated the antiproliferative effect of three anticancer drugs: doxorubicin, paclitaxel and tamoxifen in 3-D model vs in 2-D monolayer. With optimized composition of microparticles and cell culture conditions, a density of 4.5 x 10 (6) MCF-7 cells/mg of microparticles, which is an 18-fold increase from the seeding density, was achieved in six days of culture. Cells were observed to have grown in clumps on the microparticle surface as well as in their interior matrix structure. The antiproliferative effect of the drugs in 3-D model was significantly lower than in 2-D monolayer, which was evident from the 12- to 23-fold differences in their IC 50 values. Using doxorubicin, the flow cytometry data demonstrated approximately 2.6-fold lower drug accumulation in the cells grown in 3-D model than in the cells grown as 2-D monolayer. Further, only 26% of the cells in 3-D model had the same concentration of drug as the cells in monolayer, thus explaining the reduced activity of the drugs in 3-D model. The collagen content of the cells grown in 3-D model was 2-fold greater than that of the cells grown in 2-D, suggesting greater synthesis of extracellular matrix in 3-D model, which acted as a barrier to drug diffusion. The microarray analysis showed changes in several genes in cells grown in 3-D, which could also influence the drug effect. In conclusion, the cells grown in 3-D are more resistant to chemotherapy than those grown in 2-D culture, suggesting the significant roles of cellular architecture, phenotypic variations, and extracellular matrix barrier to drug transport in drug efficacy. We propose that our model provides a better assessment of drug efficacy than the currently used 2-D monolayer as many of its characteristic features are similar to an actual tumor. A well-characterized 3-D model can particularly be useful for rapid screening of a large number of therapeutics for their efficacy during the drug discovery phase.

A novel target for treatment of chordoma: signal transducers and activators of transcription 3

“…Prior research has suggested that the efficacy of potential anticancer drugs in vivo differs when compared with in vitro studies using cancer cells grown in monolayer (31,44). Because three-dimensional culture of cancer cell lines has long been advocated as a better model of the malignant phenotype in vivo (31, 45), we evaluated the effect of SD-1029 on chordoma cell lines in three-dimensional culture.…”

“…As cellular architecture may have a significant effect on drug uptake, distribution, and efficacy, drug efficacy may be significantly lower in three-dimensional models in cancer cell lines than in two-dimensional monolayer (31). To evaluate if the growth of chordoma cells could be inhibited by SD-1029 in three-dimensional culture, we measured the effect of SD-1029 on chordoma cell lines.…”

Imaging live cells grown on a three dimensional collagen matrix using Raman microspectroscopy

“…In an environment which better mimics the extracellular conditions encountered by cells in vivo, it has been possible to access more accurate information about cell homeostasis, differentiation and migration 1,2 . It is increasingly apparent that the basic 2D cell culture models commonly used fail to provide the cell a microenvironment for adequate adhesion and proliferation resulting in discrepancies between observations made in vitro and in vivo, especially for the testing of potential anticancer drugs 3 .…”

Challenges in cancer research and multifaceted approaches for cancer biomarker quest

“…Findings from such studies have highlighted the importance of cellular architecture, phenotypic variations, and extracellular matrix barrier to drug transport in cellular response to selected compounds. Combination of all these parameters contributes to the overall drug efficacy for that particular cancer or tumor [43]. These studies are aimed at the discovery of multigenic biomarkers with higher probability to better describe complex biology systems.…”