The impact of 3D tumor spheroid maturity on cell migration and invasion dynamics

Cell motility is crucial in cancer metastasis, and understanding its regulation in tumor cells is vital for developing anti-metastatic therapies. Traditional 2D cell culture assays provide insights into cell migration but fail to replicate the complex 3D architecture of tissues in vivo. 3D cell culture models like tumor spheroids have been applied for cell migration tests. This study investigates the role of spheroid maturity in tumor cell motility, hypothesizing that spheroid maturity mirrors physiological conditions in solid tumors. Human prostate (DU 145), breast (MCF-7), and murine breast (EMT-6) cancer cells were cultured into spheroids of varying time (3, 7, and 11 days). The migration and invasion of these spheroids were analyzed, revealing that 11-day-old DU 145 spheroids demonstrated the greatest horizontal migration, correlating with RNA-seq data showing increased cell adhesion, cytoskeleton dynamics, and motility pathways. Confocal microscopy and single-cell multimode analyzer indicated higher reactive oxygen species (ROS) levels in mature spheroids, potentially activating motility pathways. Additionally, DU 145 spheroids were treated with chemotherapy reagent Doxorubicin (DOX), and the results showed that spheroids culture for 7 and 11 days exhibited greater resistance to DOX compared to spheroids cultured for 3 days. These findings highlighted the importance of considering spheroid maturity in cancer research and drug development, emphasizing the need for systematic analysis of spheroid growth conditions to ensure reproducible and reliable experimental settings.