Innate immune agonist, dsRNA, induces apoptosis in ovarian cancer cells and enhances the potency of cytotoxic chemotherapeutics

Abstract

Ovarian cancer is the most lethal gynecological cancer. Here we show that innate immune agonist, dsRNA, directly induces ovarian cancer cell death and identify biomarkers associated with responsiveness to this targeted treatment. Nuclear staining and MTT assays following dsRNA stimulation revealed two subpopulations, sensitive (OVCAR-3, CAOV-3; patient samples malignant 1 and 2) and resistant (DOV-13, SKOV-3). Microarray analysis identified 75 genes with differential expression that further delineated these two subpopulations. qPCR and immunoblot analyses showed increased dsRNA receptor expression after stimulation as compared to resistant and immortalized ovarian surface epithelial cells (e.g., 70-fold with malignant 2, 43-fold with OVCAR-3). Using agonists, antagonists, and shRNA-mediated knockdown of dsRNA receptors, we show that TLR3, RIG-I, and mda5 coordinated a caspase 8/9- and interferon-dependent cell death. In resistant cells, dsRNA receptor overexpression restored dsRNA sensitivity. When dsRNA was combined with carboplatin or paclitaxel, cell viability significantly decreased over individual treatments (1.5- to 7.5-fold). Isobologram analyses showed synergism in dsRNA combinations (CI=0.4-0.82) vs. an additive effect in carboplatin/paclitaxel treatment (CI=1.5-2). Our data identify a predictive marker, dsRNA receptor expression, to target dsRNA responsive populations and show that, in dsRNA-sensitive cells, dsRNA induces apoptosis and enhances the potency of cytotoxic chemotherapeutics.

Transfected Poly(I:C) Activates Different dsRNA Receptors, Leading to Apoptosis or Immunoadjuvant Response in Androgen-independent Prostate Cancer Cells

“…IFN-␤ is known to be a key molecule in antitumoral immune response in various cancers, including PCa (40,41). Moreover, in different cancer models, IFN-␤ has been shown to mediate poly(I:C)-dependent apoptosis or growth arrest (2,37,38). In contrast, in this work, by using neutralizing antibody against IFNR, we demonstrate that in-poly(I:C)-induced apoptosis takes place independently of IFN-␤ in androgen-independent PCa cells.…”

“…After demonstrating that in-poly(I:C)-apoptosis is IRF3-independent but is accompanied by IFN-␤ increased expression, we evaluated whether IFN-␤ mediates in an autocrine fashion in-poly(I:C)-triggered apoptosis, as described previously in different cancer cell lines (2,37,38). With this aim, we blocked type I interferon receptor (IFNR-1) by a neutralizing antibody, and we assessed apoptosis rate after in-poly(I:C) treatment in PC3 cells.…”

Overview on poly(ADP-ribose) immuno-biomedicine and future prospects

“…Moreover, I expect heteroclitic/heterospecific actions by poly(ADP-ribose) sensitization in vivo , as seen, for example, in a report by Sibley et al 97) In this context, the possible presence with as yet undetermined naturally occurring double stranded RNAs may augment its function in which innate immunity and Toll-like receptors (TLRs) are involved. 98–102) In this sense, it might be of use to apply the classic method to produce a large amounts of poly(ADP-ribose) as far as calf thymuses a source of PARP are available. 103) …”

Mouse Embryonic Stem Cells Have Underdeveloped Antiviral Mechanisms That Can Be Exploited for the Development of mRNA-Mediated Gene Expression Strategy

“…We first determined potency of these short ssRNA in eliciting antiviral responses in a human ovarian epithelial carcinoma cell line (SKOV3 cells), which have been previously used as a model to study the immunogenicity of different types of RNA [38][39][40]. Using IFNb expression as a benchmark for antiviral responses, our data showed that only 3p-ssRNA with longer than 60 nt induced IFNb, whereas the removal of the 3p group completely abolished this effect, as demonstrated in the case of 3p-80nt-ssRNA (Fig.…”