IMMU-56. TARGETING NONO IN GLIOMA VIROIMMUNOTHERAPY

Abstract

Abstract Despite aggressive therapies, the median survival for glioblastoma (GBM) patients remains just 7-months after tumor progression. Oncolytic virotherapy is a promising approach to reprogramming the immunosuppressed microenvironment of GBMs facilitating anti-tumor immunity. Delta-24-RGD is an oncolytic adenovirus that has shown favorable results in phase I/II clinical trials (NCT00805376, NCT03178032 and NCT02798406). However, the immune response of the patient functionally cleared the virus, limiting its anti-cancer efficacy to a subset (~20%) of patients. It is known that Non-POU Domain Containing Octamer Binding (NONO) is overexpressed in gliomas and is associated with poor survival of patients. Using bulk RNA sequencing, we showed that the NONO pathway is upregulated 7 folds during adenoviral infection. These results were confirmed by western blot analyses that showed a significant increase in the expression of NONO after Delta-24-RGD infection. We detected cellular and viral members of the NONO interactome using mass spectrometry analyses. Immunoprecipitation assays confirmed those results and showed that NONO binds to adenoviral proteins during infection and associates with the foreign DNA sensor cyclic GMP AMP synthase (cGAS). Using shRNA knockdown, we showed that NONO was required to induce innate immune activation in response to adenovirus infection. Thus, we observed a 180-fold increase in type I interferon after the infection with the virus that was reversed in NONO-null cells. Therefore, NONO is a previously undetected innate immune sensor of adenoviruses in the nucleus. In addition, the fact that NONO binds adenoviral proteins suggests a new double-sensor mechanism involving the detection of both foreign DNA and viral proteins. Interactions between NONO and adenoviral proteins should be considered when designing the next generation of oncolytic adenovirus for the treatment of gliomas.