The use of lytic viruses to preferentially infect and eliminate cancer cells while sparing normal cells is a promising experimental therapeutic approach for treating cancer. However, the efficacy of oncolytic virotherapy is often limited by two innate immunity pathways, the protein kinase PKR and the 2'-5'-oligoadenylate (OAS)/RNase L systems, which are widely present in many but not all tumor cell types. Previously, we reported that the anticancer drug, sunitinib, an inhibitor of VEGF-R and PDGF-R, has off-target effects against both PKR and RNase L. Here we show that combining sunitinib treatments with infection by an oncolytic virus, vesicular stomatitis virus (VSV), led to the elimination of prostate, breast, and kidney malignant tumors in mice. In contrast, either virus or sunitinib alone slowed tumor progression but did not eliminate tumors. In prostate tumors excised from treated mice, sunitinib decreased levels of the phosphorylated form of translation initiation factor, eIF2-α, a substrate of PKR, by 10-fold while increasing median viral titers by 23-fold. The sunitinib/VSV regimen caused complete and sustained tumor regression in both immunodeficient and immunocompetent animals. Results indicate that transient inhibition of innate immunity with sunitinib enhances oncolytic virotherapy allowing the recovery of tumor-bearing animals.

RNase L and RNA-dependent protein kinase (PKR) are effectors of the interferon antiviral response that share homology in their pseudokinase and protein kinase domains, respectively. Sunitinib is an orally available, ATP-competitive inhibitor of VEGF and PDGF receptors used clinically to suppress angiogenesis and tumor growth. Sunitinib also impacts IRE1, an endoplasmic reticulum protein involved in the unfolded protein response that is closely related to RNase L. Here, we report that sunitinib is a potent inhibitor of both RNase L and PKR with IC 50 values of 1.4 and 0.3 M, respectively. In addition, flavonol activators of IRE1 inhibited RNase L. Sunitinib treatment of wild type (WT) mouse embryonic fibroblasts resulted in about a 12-fold increase in encephalomyocarditis virus titers. However, sunitinib had no effect on encephalomyocarditis virus growth in cells lacking both PKR and RNase L. Furthermore, oral delivery of sunitinib in WT mice resulted in 10-fold higher viral titers in heart tissues while suppressing by about 2-fold the IFN-␤ levels. In contrast, sunitinib had no effect on viral titers in mice deficient in both RNase L and PKR. Also, sunitinib reduced mean survival times from 12 to 6 days in virus-infected WT mice while having no effect on survival of mice lacking both RNase L and PKR. Results indicate that sunitinib treatments prevent antiviral innate immune responses mediated by RNase L and PKR.RNase L and PKR 2 are host enzymes of higher vertebrates that participate in innate immunity against viral infections (1-4). Activation of both RNase L and PKR is triggered by the viral pathogen-associated molecular pattern, double-stranded RNA (dsRNA). However, whereas dsRNA directly binds to and activates PKR, in the case of RNase L activation is indirect. Interferon (IFN) treatment of cells induces PKR that, upon binding to dsRNA, phosphorylates first itself and then EIF2␣ thus blocking protein synthesis among other effects. RNase L degrades single-stranded RNA resulting in pleiotropic antiviral effects (5). Short 5Ј-triphosphorylated, 2Ј,5Ј-oligoadenylates (2-5A) are produced from ATP when viral dsRNA stimulates IFN-inducible oligoadenylate synthetases. 2-5A binds ankyrin repeats 2 and 4 in the N-terminal region of RNase L causing its dimerization and activation (6). RNase L is also pseudokinase with amino acid sequence homology to the PKR kinase domains (7).IRE1, a kinase and endoribonuclease involved in the unfolded protein response, is another relative of RNase L (8). IRE1 spans the endoplasmic reticulum (ER) membrane. The intralumenal domains of IRE1 directly or indirectly sense unfolded proteins in the ER leading to autophosphorylation and ribonuclease activities in the cytoplasmic domains. IRE1 excises an intron from pre-mRNA for a transcription factor (HAC1 in yeast and XBP1 in mammals) leading to splicing and translation (9). HAC1/XBP1 drives expression of ER chaperones and protein folding enzymes that re-establish ER function. The kinase-extension-nuclease (KEN) domains of RNase L and IRE1 ar...

Background The endoribonuclease RNase-L is a type-I interferon (IFN)-regulatedcomponent of the innate immune response that functions in antiviral, antibacterial and antiproliferative activities. RNase-L produces RNA agonists of RIG-I-like receptors (RLRs), sensors of cytosolic pathogen-associated RNAs that induce cytokines including IFNβ. IFNβ and RLR signaling mediate protective responses against experimental colitis and colitis-associated cancer (CAC) and contribute to gastrointestinal (GI) homeostasis. Therefore, we investigated a role for RNase-L in murine colitis and CAC and its association with RLR signaling in response to bacterial RNA. Methods Colitis was induced in wild type (WT) and RNase-L-deficient mice (RNase-L−/−) by administration of dextran sulphate sodium (DSS). CAC was induced by DSS and azoxymethane (AOM). Histological analysis and immunohistochemistry were performed on colon tissue to analyze immune cell infiltration and tissue damage following induction of colitis. Expression of cytokines was measured by qRT-PCR and ELISA. Results DSS-treated RNase-L−/− mice exhibited a significantly higher clinical score, delayed leukocyte infiltration, reduced expression of IFNβ, TNFα, IL-1β and IL-18at early times post-DSS exposure and increased mortalityas compared to WT mice. DSS/AOM-treated RNase-L−/−mice displayed an increased tumor burden. Bacterial RNA triggeredIFNβproductionin an RNase-L-dependent manner and provided a potential mechanism by whichRNase-L contributes to the GI immune response to microbiota and protects against experimental colitis and CAC. Conclusions RNase-L promotes the innate immune response to intestinal damage and ameliorates murine colitis and CAC. The RNase-L-dependent production of IFNβ stimulated by bacterial RNA may be a mechanism to protectagainst GI inflammatory disease.

The present study reports on the frequency and the spectrum of genetic variants causative of monogenic diabetes in russian children with non-type 1 diabetes mellitus. The present study included 60 unrelated russian children with non-type 1 diabetes mellitus diagnosed before the age of 18 years. Genetic variants were screened using whole-exome sequencing (WeS) in a panel of 35 genes causative of maturity onset diabetes of the young (ModY) and transient or permanent neonatal diabetes. Verification of the WeS results was performed using Pcr-direct sequencing. a total of 38 genetic variants were identified in 33 out of 60 patients (55%). The majority of patients (27/33, 81.8%) had variants in ModY-related genes: GCK (n=19), HNF1A (n=2), PAX4 (n=1), ABCC8 (n=1), KCNJ11 (n=1), GCK+HNF1A (n=1), GCK+BLK (n=1) and GCK+BLK+WFS1 (n=1). a total of 6 patients (6/33, 18.2%) had variants in ModY-unrelated genes: GATA6 (n=1), WFS1 (n=3), EIF2AK3 (n=1) and SLC19A2 (n=1). a total of 15 out of 38 variants were novel, including GCK, HNF1A, BLK, WFS1, EIF2AK3 and SLC19A2. To summarize, the present study demonstrates a high frequency and a wide spectrum of genetic variants causative of monogenic diabetes in russian children with non-type 1 diabetes mellitus. The spectrum includes previously known and novel variants in ModY-related and unrelated genes, with multiple variants in a number of patients. The prevalence of GCK variants indicates that diagnostics of monogenic diabetes in russian children may begin with testing for ModY2. However, the remaining variants are present at low frequencies in 9 different genes, altogether amounting to ~50% of the cases and highlighting the efficiency of using WES in non-GCK-ModY cases.

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