RIG-Ⅰ-dependent Signaling In Tumors Affects Therapeutic Effect Of Oncolytic Vesicular Stomatitis Virus

Oncolytic virus therapy is one of the most promising methods for tumor treatment.At present,a variety of oncolytic virus therapy is in the laboratory research stage or developed to clinical treatment stage.Oncolytic viruses have abilities to inhibit proliferation of tumor cells and promote tumor cell death through many mechanisms,including oncolytic virus specific rapid expansion in tumor cells resulting in tumor cell lysis,recognition and killing of tumor cells by activating immune system.In addition,oncolytic viruses can inhibit the tumor cell metastasis by inhibiting the angiogenesis of newborn tumor.According to the difference of genetic material,the oncolytic viruses are generally divided into two types: DNA as genetic material viruses and RNA as genetic material viruses.Some components of pathogenic microorganisms,such as DNA or RNA in viruses,are recognized by pattern recognition receptors(PRRs)and induce the cells to produce innate immune responses,further activate the acquired immunity.Recent studies have shown that the oncolytic viruses can activate the innate immunity and acquired immunity,and promote the antitumor immunity.However,the innate immunity in tumor has rarely been paid attention to in oncolytic virus tumor therapy.Therefore,we focus on the effect of RIG-I signaling pathway in tumor cells on oncolytic virus tumor therapyIn this study,we used RNA virus VSVΔ51/Se V and DNA virus HSV-1 to induce tumor cells innate immune response.The results showed that the RNA virus VSVΔ51/Se V was more easily to activate the innate immune response than DNA virus HSV-1 in tumor cells.In order to further study the mechanisms of oncolytic virus therapy,we used RNA-seq to study the expression profile in human lung adenocarcinoma cell A549 infected by VSVΔ51.The results showed that VSVΔ51 could induce A549 to upregulate a variety of cytokines related to the activation,proliferation and recruitment of immune cells.The results of GO enrichment analysis showed that many signaling pathways and biological processes were changed after A549 infection with VSVΔ51.These changes not only induced signaling pathway related to tumor apoptosis,but also made tumor cells more easily recognized by immune cells.Moreover,we selected normal lung somatic cells 16 HBE for RNA-seq,and the results showed that VSVΔ51 had little effect on 16 HBE compared with A549.In addition,RNA-seq analysis showed that a variety of RNA sensor were upregulated after VSVΔ51 induced A549 innate immune response.RIG-I plays key roles in recognizing VSVΔ51 and inducing A549 cells to produce IFNB1 and other proinflammatory signals.The results showed that knockdown of RIG-I significantly reduced the expression of IFNB1 and other proinflammatory signals in A549 cells.Besides,VSVΔ51 can also induce A375,LLC cells to produce proinflammatory signals,and RIG-I plays an important role in promoting A375,LLC innate immune response.On the one hand,these inflammatory signals can promote the immune system to eliminate tumor cells,on the other hand,they may also inhibit the rapid expansion of oncolytic virus in tumor.Therefore,we knocked down RIG-I in A549,A375 and LLC respectively and detected expansion of VSVΔ51 in tumor cells.The results showed that after knocking down RIG-I,VSVΔ51 proliferated faster and produced more viruses in these three cells.In order to further understand the role of RIG-I signaling pathway in tumor cells in oncolytic virus tumor therapy.We injected sh Control and sh RIG-I LLC into C57 mice to establish LLC tumor model,and used VSVΔ51 to treat tumor model.The results showed that oncolytic virus VSVΔ51 had therapeutic effect on sh Control and sh RIG-I LLC,and VSVΔ51 had more obvious effect on sh RIG-I LLC.In conclusion,the amplification of VSVΔ51 can result in changes of signaling pathways and biological processes in A549,which can promote tumor apoptosis and enhance tumor immunogenicity.In addition,VSVΔ51 activates the RIG-I receptor in A549,A375 and LLC cells,induces the innate immune response and produces proinflammatory signals such as IFNB1.At the same time,the activation of RIG-I signaling pathway inhibits oncolytic virus VSVΔ51 replication in tumor cells.Because RIG-I in tumor may have both positive and negative regulation,we further elucidated the role of RIG-I in tumor by mouse tumor model.The results showed that RIG-I in tumors inhibited the therapeutic effect of virus on tumors.Our researchs explored the role of RNA sensor in oncolytic virus tumor therapy,and provided a new development idea for oncolytic virus therapy.