Glioblastoma multiforme (GBM) is an aggressive primary brain tumor characterized by rapid and extensive invasion into surrounding brain tissue. GBM invasion is known to involve tumor cell proliferation and remodeling of the extracellular matrix (ECM), yet the relative contributions of these processes over the course of tumor growth in spheroid models remain poorly understood. In this study, a spheroid model was used to investigate how proliferation and ECM deposition influence GBM spheroid growth. U87-MG spheroids were cultured for 14 days and assessed for changes in size, metabolic activity (Alamar Blue), proliferative behavior (Ki-67), and ECM remodeling at different timepoints. ECM remodeling was analyzed by immunofluorescent staining and confocal microscopy of hyaluronic acid and collagen types I, VI, and IX, which regulate matrix architecture and mechanical properties. Spheroid size increased throughout the culture period (Day 3: 116.8±57.7µm; Day 7: 155.6±90.77µm, p=0.0019). Early spheroid expansion was associated with high proliferative activity, low metabolic activity, and matrix deposition. Later timepoints exhibited reduced proliferation (Day 3: 51.5±17.9%; Day 7: 28.1±22.1%, p<0.0001) while demonstrating increased metabolic activity (relative increase in metabolic activity from day 3 to 7: 1.89±0.76) and ECM remodeling. These findings indicate that GBM spheroid growth is governed by mechanisms at different stages, with early growth dominated by proliferation and later growth increasingly supported by ECM deposition. This shift likely reflects adaptive strategies that allow GBM to meet the demands of its microenvironment, supporting its survival under changing conditions.

Co-authors: None