Comparison of two-dimensional and three-dimensional culture systems and their responses to chemotherapy in cells representing disease progression of high-grade serous ovarian cancer

High-grade serous cancer is the most common type of ovarian cancer and is usually diagnosed at advanced stages with high mortality due to recurrence and eventual resistance to standard platinum therapy. The aim of this study was to compare two-dimensional (2D) versus tridimensional (3D) cell culture as a preclinical model of response to carboplatin, paclitaxel and niraparib using PEO1, PEO4 and PEO6 cell lines, which were generated from the same patient along disease progression. Morphologically, cells formed flat adherent layers versus spheroidal structures with different compaction patterns in 2D and 3D respectively. In 2D, apoptosis was rare whereas in 3D cells formed a multilayered structure with an outer layer of live proliferating cells and an inner core of apoptotic cells. Furthermore, a differential capacity to produce ATP was observed among the cell lines in 3D but not in 2D. While response to carboplatin, paclitaxel and niraparib in both settings followed a similar trend, a lower sensitivity was observed in 3D with respect to 2D. Overall, 3D cell culture is likely more reflective of the <i>in vivo</i> cellular tumor behavior and more suitable of therapeutic evaluation given its added complexity absent in 2D.