BH3 mimetic ABT-737 sensitizes colorectal cancer cells to ixazomib through MCL-1 downregulation and autophagy inhibition.

The proteasome inhibitor MLN9708 is an orally administered drug that is hydrolyzed into its active form, MLN2238 (ixazomib). Compared with Bortezomib, MLN2238 has a shorter proteasome dissociation half-life and a lower incidence and severity of peripheral neuropathy, which makes it an attractive candidate for colorectal cancer treatment. In the present study, we observed that MLN2238 induced autophagy, as evidenced by conversion of the autophagosomal marker LC3 from LC3I to LC3II, in colorectal cancer cell lines. Mcl-1, an anti-apoptotic Bcl-2 family protein, was markedly elevated after treating a colorectal cancer cell line with MLN2238. We proved that inhibiting Mcl-1 expression enhances MLN2238 induced apoptosis and negatively regulates autophagy. Co-administration of BH3 mimetic ABT-737 with MLN2238 synergistically kills colorectal cancer cells through MCL-1 neutralization and autophagy inhibition. Furthermore, the synergistic killing effect of the combination therapy is correlated with P53 status in colorectal cancer. These data highlight that the combination of ABT-737 with MLN9708 is a promising therapeutic strategy for human colorectal cancer

Expression of Interferon Gamma by a Recombinant Rabies Virus Strongly Attenuates the Pathogenicity of the Virus via Induction of Type I Interferon.

UNLABELLED: Previous animal model experiments have shown a correlation between interferon gamma (IFN-γ) expression and both survival from infection with attenuated rabies virus (RABV) and reduction of neurological sequelae. Therefore, we hypothesized that rapid production of murine IFN-γ by the rabies virus itself would induce a more robust antiviral response than would occur naturally in mice. To test this hypothesis, we used reverse engineering to clone the mouse IFN-γ gene into a pathogenic rabies virus backbone, SPBN, to produce the recombinant rabies virus designated SPBNγ. Morbidity and mortality were monitored in mice infected intranasally with SPBNγ or SPBN(-) control virus to determine the degree of attenuation caused by the expression of IFN-γ. Incorporation of IFN-γ into the rabies virus genome highly attenuated the virus. SPBNγ has a 50% lethal dose (LD50) more than 100-fold greater than SPBN(-). In vitro and in vivo mouse experiments show that SPBNγ infection enhances the production of type I interferons. Furthermore, knockout mice lacking the ability to signal through the type I interferon receptor (IFNAR(-/-)) cannot control the SPBNγ infection and rapidly die. These data suggest that IFN-γ production has antiviral effects in rabies, largely due to the induction of type I interferons. IMPORTANCE: Survival from rabies is dependent upon the early control of virus replication and spread. Once the virus reaches the central nervous system (CNS), this becomes highly problematic. Studies of CNS immunity to RABV have shown that control of replication begins at the onset of T cell entry and IFN-γ production in the CNS prior to the appearance of virus-neutralizing antibodies. Moreover, antibody-deficient mice are able to control but not clear attenuated RABV from the CNS. We find here that IFN-γ triggers the early production of type I interferons with the expected antiviral effects. We also show that engineering a lethal rabies virus to express IFN-γ directly in the infected tissue reduces rabies virus replication and spread, limiting its pathogenicity in normal and immunocompromised mice. Therefore, vector delivery of IFN-γ to the brain may have the potential to treat individuals who would otherwise succumb to infection with rabies virus

Expression of interferon gamma by recombinant rabies virus strongly attenuates virus pathogenicity and enhances safety and efficacy of post-exposure treatment vectors

Animal model experiments have shown interferon gamma (IFNγ) expression correlates with survival from infection with attenuated rabies virus and reduction of neurological sequelae. Therefore, we hypothesized that rapid production of IFNγ by the rabies virus itself would induce a more robust antiviral response than would occur naturally, thereby attenuating the virus and enhancing its safety and efficacy as pre- and post-exposure treatment for rabies. We reverse-engineered IFNγ-expressing recombinant RABV: SPBNγ, GASγ and GASγGAS. Morbidity and mortality were monitored in mice infected intranasally with SPBNγ or control virus to determine the degree of attenuation attributable to viral IFNγ. Incorporation of IFNγ into the rabies genome highly attenuated the virus. SPBNγ has an LD50 more than 100 fold greater than SPBN(-). Subsequent experiments were designed to assess how viral IFNγ expression could attenuate SPBNγ, and determine the ability of virus-expressed IFNγ to improve the safety and immunogenicity of existing vaccine vectors for use as pre- and post-exposure treatment (PET). In vitro and in vivo mouse experiments show that SPBNγ infection enhances type I IFN expression, in the absence of increased viral replication. Furthermore, knockout mice lacking the type I interferon receptor (IFNAR-/-) rapidly die from SPBNγ infection. Since SPBNγ retains residual pathogenicity in adult mice, we used GASγ and GASγGAS, constructed on attenuated backbones, for subsequent studies. Mortality and morbidity were monitored in suckling mice and models of pre- and post-exposure treatment. Behavioral testing was also used to measure neurological deficits in mice surviving PET. We demonstrate that GASγ and GASγGAS are significantly attenuated in suckling mice compared to the highly attenuated GASGAS vaccine. GASγ better protects mice from lethal DRV4 RABV infection in both pre- and post-exposure models compared to GASGAS. Finally, GASγGAS significantly reduces post-infection neurological sequelae, compared to its control vector, during PET of DRV4 infection. We conclude that expression of IFNγ by a vaccine vector can further enhance its safety profile while increasing its efficacy as a traditional vaccine and PET. Furthermore, the mechanism of attenuation is due, at least in part, to increased induction of type I IFN