Abstract B52: Inhibition of ovarian cancer spheroid adhesion using graphene oxide nanomaterials

Abstract

Abstract There is an urgent need for development of alternative treatment strategies for advanced-stage ovarian cancer. During metastatic spread, single cells or spheroids detach from the primary tumor and are carried by the peritoneal fluid until attaching to the mesothelial cells lining the abdominal cavity. While attachment of ovarian tumor cells and spheroids to the mesothelial layer is known to be mediated by β-integrins and CD44, efforts to block these receptors with antibodies have been insufficient to inhibit disease progression. As graphene oxide nanosheets have previously been shown bind to β-integrins on the surface of mesenchymal stem cells, we hypothesized that they would be able to attach to ovarian cancer spheroids, forming a physical barrier around the spheroids and thus inhibiting their adhesion to the mesothelium. SKOV-3 human ovarian cancer cells were used in this study, as this cell line was derived from ascites fluid. SKOV-3 cells were placed in poly(hydroxyethyl methacrylate) (polyHEMA)-coated plates for 24 hours to form spheroids, followed by 48-hour treatment with the nanosheets. The graphene oxide nanosheets were functionalized with 4-arm polyethylene glycol (PEG) to enhance biocompatibility and provide additional steric hindrance to prevent spheroid adhesion. Scanning electron microscopy confirmed that the nanosheets were able to bind to the tumor spheroids. Association of the nanosheets with the SKOV-3 spheroids reduced their adhesion to extracellular matrix proteins collagen and fibronectin as well as LP-9 human mesothelial cells over a 7-day time period, with the PEG-functionalized nanosheets showing the greatest reduction in adhesion. The nanomaterials did not exhibit cytotoxicity to LP-9 cells at the range of concentrations used to prevent adhesion. Receptor blocking studies confirmed that the nanosheets were predominantly engaging with the tumor spheroids via β-integrins. Finally, for tumor spheroids that did bind to the mesothelial cells, the presence of nanosheets on the surface of the spheroids decreased the rate of mesothelial layer clearance by the tumor cells. Taken together, these results demonstrate that graphene oxide nanomaterials can bind to ovarian tumor spheroids and inhibit their attachment to matrix proteins and mesothelial cells, while also reducing their ability to clear mesothelial cells once bound. Future efforts are focused on testing these materials with human ascites fluid and further modifying the nanosheets to enable ablation of tumor cells bound to the nanosheets to enhance their therapeutic potential. Citation Format: Hak Rae Lee, Melissa A. Geller, Samira M. Azarin. Inhibition of ovarian cancer spheroid adhesion using graphene oxide nanomaterials [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B52.