Abstract 5824: Human ovarian cancer cell seeding density as a mechanism of cisplatin resistance associated with expression of anti-apoptotic and autophagy proteins

Abstract

Abstract Drug effects may vary depending on cancer cell density. We investigated discrepancies in phenotypes for high density and low-density cultured cancer cells and elucidated relevant variables that influence them. We assessed chemosensitivity as a function of tumor cell density by plating TOV-21G and OVMANA ovarian cancer cell lines in 96-well plates at various seeding densities per well and treated them with various concentrations of cisplatin. CellTiterGlo assays were performed at 72 hours of treatment to determine cisplatin dose response curves. We used ethidium homodimer fluorescence staining and imaging to quantify extent of cell death at differing cell densities of TOV-21G and OVMANA cells treated with cisplatin for 48 and 72hours in 48-well plates. We performed western blot analyses of apoptotic and autophagy proteins from TOV-21G and OVMANA cells that were seeded at high and low cell densities in 24-wellplates. TOV-21G and OVMANA cells plated at higher cell seeding densities displayed less cisplatin sensitivity than TOV-21G and OVMANA cells plated at lower seeding densities, as shown by cisplatin dose response curves. Ethidium homodimer staining of TOV-21G and OVMANA cells treated with cisplatin revealed that cells seeded at lower densities experience a greater amount of cell death that cells seeded at higher densities. Western blot analyses showed that high density TOV-21G cells may express greater amounts of BCL2 and c-FLIP and lower amounts of p62 and NOXA compared to low density cells when normalized for protein expression. Similarly, high density OVMANA cells express greater amounts of c-FLIP andBCL2 and lower amounts of NOXA compared to low density cells when normalized for protein expression. Our experiments reveal that human ovarian cancer cells display different phenotypic changes depending on cell density, causing higher density cells to require increased cisplatin to achieve the same level of effect seen in lower density cells. Ovarian cancer cell resistance to cisplatin is associated with alterations in autophagy and anti-apoptotic protein expression at high cell seeding density. These alterations may also affect chemosensitivity in vivo in settings of differential tumor density, such as single circulating tumor cells compared to clumps of tumor cells, and other settings, such as metastasis. Citation Format: Thomas W. Brown, Ujwal Punyamurtula, Wafik S. El-Deiry. Human ovarian cancer cell seeding density as a mechanism of cisplatin resistance associated with expression of anti-apoptotic and autophagy proteins. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5824.