Evaluation of cancer stemness in breast cancer and glioblastoma spheroids in vitro.

In this study, the effect of spheroid formation, as a model of three-dimensional (3D) culture systems, on the cancer stemness of human breast cancer (MCF-7) and human glioma (U87-MG) cell lines was analyzed. We compared the expression of pluripotency genes, the presence of various cancer stem cell populations, migration and proliferation capacities of cells cultured as monolayers or spheroids. MCF-7 cells formed uniform spheroids in vitro, upregulated the expression of stem cell markers both at gene and protein levels and increased their migration capacities when cultured in 3D systems. When a CSC targeting metabolic drug, metformin was used, multiple drug resistance genes (ABC transporters) were downregulated and the anti-cancer activity of 5-fluorouracil was enhanced. In summary, this study proved that the use of 3D culture systems such as spheroids can be used in CSC-related research. Therefore, studies involving 3D culture systems will help scientists to discover new CSC markers, show more realistic drug responses, and better evaluate tumor proliferation and morphology changes.