Characterization of an Alginate Encapsulated LS180 Spheroid Model for Anti-colorectal Cancer Compound Screening

Colorectal cancer is one of the leading causes of cancer-related deaths. A main problem for its treatment is resistance to chemotherapy, requiring the development of new drugs. The success rate of new candidate cancer drugs in clinical trials remains dismal. Three-dimensional (3D) cell culture models have been proposed to bridge the current gap between in vitro chemotherapeutic studies and the human in vivo, due to shortcomings in the physiological relevance of the commonly used two-dimensional cell culture models. In this study, LS180 colorectal cancer cells were cultured as 3D sodium alginate encapsulated spheroids in clinostat bioreactors. Growth and viability were evaluated for 20 days to determine the ideal experimental window. The 3- (4,5- dimethylthiazol- 2- yl)-2,5-diphenyltetrazolium bromide assay was then used to establish half maximal inhibitory concentrations for the standard chemotherapeutic drug, paclitaxel. This concentration was used to further evaluate the established 3D model. During model characterization and evaluation soluble protein content, intracellular adenosine triphosphate levels, extracellular adenylate kinase, glucose consumption, and P-glycoprotein (P-gp) gene expression were measured. Use of the model for chemotherapeutic treatment screening was evaluated using two concentrations of paclitaxel, and treatment continued for 96 h. Paclitaxel caused a decrease in cell growth, viability, and glucose consumption in the model. Furthermore, relative expression of P-gp increased compared to the untreated control group. This is a typical resistance-producing change, seen in vivo and known to be a result of paclitaxel treatment. It was concluded that the LS180 sodium alginate encapsulated spheroid model could be used for testing new chemotherapeutic compounds for colorectal cancer.