Phytoglycogen-dsRNA nanoparticles demonstrate differential cytotoxicity and immunostimulatory potential in two ovarian cancer cell lines

Abstract

Background Ovarian cancer is a leading cause of cancer mortality in women, and only a small percentage of cases are caught at an early stage. Novel treatments with improved efficacy are needed to fight ovarian cancer and to overcome resistance to traditional therapies. Double-stranded (ds) RNA, including the synthetic polyinosinic cytidylic acid (poly (I:C), has shown promise as a cancer therapeutic. Two ovarian cancer cell lines were tested for their ability to produce an immune response to poly (I:C) delivered using a nanoparticle carrier, a biodegradable phytoglycogen derived from sweet corn, called nanodendrix (NDX). SKOV-3 and OVCAR-3 have been previously identified as dsRNA-resistant and dsRNA-sensitive, respectively. Results Firstly, NDX was found to effectively bind poly (I:C), at a w/w ratio of 2:1 NDX:poly (I:C), the resulting particles, poly (I:C)-NDX, were tested for biological activity through uptake and two therapeutic modes of action, cytotoxicity and stimulation of the innate immune response. Both cell lines bound poly (I:C)-NDX, as observed using immunocytochemistry. In OVCAR-3 poly (I:C)-NDX caused significant cell death, even at concentrations as low as 62.5ng/mL, measured using the cell viability indicator dye alamarBlue; no cell death was observed with poly (I:C) alone across all concentrations, up to 5µg/mL in SKOV-3 and 0.5µg/mL in OVCAR-3. In both OVCAR-3 and SKOV-3, poly (I:C)-NDX stimulated the production of an innate immune chemokine, CXCL10, at the transcript and protein levels, at significantly higher levels than poly (I:C) alone. Interestingly, in response to poly (I:C)-NDX SKOV-3 produced a more robust immune response compared and higher levels of capase-3/-7 activation compared to OVCAR-3, despite showing no significant cell death. Conclusions Poly (I:C)-NDX represents a robust and multifunctional therapy with demonstrated efficacy against a range of ovarian tumour cells, potentiating poly (I:C) and sensitizing resistant cells. Additionally, the SKOV-3 and OVCAR-3 combination represents a powerful comparative model to help unravel dsRNA-mediated immune responses in ovarian cancer cells.