Date of Award

5-2023

Document Type

Thesis

Department

Bioengineering

Committee Chair/Advisor

Kharimat Lora Alatise

Abstract

Ovarian cancer is the sixth leading cause of death among women worldwide, with an average 5-year survival rate of less than 48%. Current clinical treatment methods for this disease are often deemed ineffective because of the innate chemoresistance of tumors due to their microenvironment and architecture. Accurately mimicking chemoresistance with traditional 2D cultures is difficult; therefore, recent years have seen an increase in 3D culturing methods that create cellular spheroids. These spheroids can serve as models of in vivo tumor characteristics due to their hypoxic core, acidic microenvironment, and increased cell-to-cell interactions. This research aims to (1) refine a 3D culture protocol that allows for the consistent formation of ovarian cancer spheroids, and (2) evaluate the spheroids for their physical and molecular properties as it relates to chemoresistance in ovarian cancer.

Both ES-2 and OVCAR-3 ovarian cancer cell lines formed aggregates of 500 μm within 24 hours of seeding, yet the ES-2 spheroids were much more compact than the OVCAR-3 aggregates. 3D ES-2 cultures showed significantly increased chemoresistance to treatment with chemotherapeutic paclitaxel in comparison to 2D ES-2 cultures. Histochemical staining of ES-2 spheroids showed tight cellular congregation along the outer rim of the spheroid and sparse cellular distribution near the core, meaning that outer cells are proliferating whereas core cells are necrotic. From this, we concluded that our spheroids display a structure similar to those noted as recapitulating in vivo tumors in previous literature. Lastly, western blotting revealed that changes in protein expression began to occur at four days of spheroid growth.

Our results demonstrate morphological differences in tumor spheroids of two different ovarian cancer cell lines. Additionally, we’ve found that cells grown in 3D display increased chemoresistance in comparison to 2D-cultured cells, confirming the spheroids’ ability to provide translatable in vitro results compared to in vivo tumor characteristics. Lastly, the spheroids displayed concentric cellular zones that indicate tumor-like spheroid formation according to previous literature, as well as differential expression of oncogenic proteins compared to traditional 2D cultures.

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