Ovarian cancer cell heterogeneity and paclitaxel response in vitro 2D and 3D cancer cell models and xenograft growth in the chicken chorioallantoic membrane (CAM).

Among gynecological malignancies, epithelial ovarian cancer (EOC) is the most lethal, comprising a heterogeneous group of diseases. Paclitaxel is a standard chemotherapeutic agent and an important option for EOC treatment. However, chemotherapy often fails, contributing to a high rate of EOC recurrence. One of the models that best explains the cellular heterogeneity, disease aggressiveness, chemoresistance, recurrence risk, and metastasis observed in ovarian tumors is the presence of cancer stem cells (CSCs). This study aimed to assess the phenotypic changes in three EOC cell lines (TOV-21G, SKOV-3, and OV-90) cultured in monolayer (MN) and tumorsphere (CSCs enrichment-TS) models. After treatment with paclitaxel, we studied different cell subpopulations by immunophenotyping using CSC markers (CD44/CD24) and mesenchymal markers (CD117/CD146). The relative expression of mRNAs (CASP8, TNFRSF10B, TP53, and BCL2) and miRNAs (miR-26a, miR-125b-5p, miR-181c, miR-17-5p, and miR-221) was evaluated by qPCR. In addition, we assessed the growth capacity of residual cells treated with paclitaxel using the chorioallantoic membrane (CAM) model to study disease relapse. After paclitaxel exposure, OV-90 TS and TOV-21G TS cells showed an increase in cell growth ability, while SKOV-3 MN cells maintained colony formation capability. SKOV-3 MN cells were enriched in the CSC-like subset (CD24-/CD44+), and showed CASP8 downregulation, suggesting that this profile is associated with increased paclitaxel resistance. Tumors derived from residual cells exposed to paclitaxel and grafted onto the CAM displayed organizational patterns distinct from those of the control tumors. These findings strongly support the notion that defining tumor phenotypic characteristics could aid in developing more effective therapeutic strategies and new drug targets.