AZD1775 and anti-PD-1 antibody synergistically sensitize hepatoma to radiotherapy

Background:Radiation(IR)-induced DNA damage triggers cell cycle arrest and has a suppressive effect on the tumor microenvironment(TME).Wee1,a cell cycle regulator,can eliminate G2/M arrest by phosphorylating cyclin-dependent kinase 1(CDK1).Meanwhile,programed death-1/programed death ligand-1(PD-1/PDL-1)blockade is closely related to TME.This study aims to investigate the effects and mechanisms of Wee1 inhibitor AZD1775 and anti-PD-1 antibody(anti-PD-1 Ab)on radiosensitization of hepatoma.Methods:The anti-tumor activity of AZD1775 and IR was determined by 3-(4,5-dimethylthiazol-2-y1)-2,5-diphenyltetrazolium bromide(MTT)assay on human and mouse hepatoma cells HepG2,Hepa1-6,and H22.The anti-hepatoma mechanism of AZD1775 and IR revealed by flow cytometry and Western blot in vitro.A hepatoma subcutaneous xenograft mice model was constructed on Balb/c mice,which were divided into control group,IR group,AZD1775 group,IR+AZD1775 group,IR+anti-PD-1 Ab group,and the IR+AZD1775+anti-PD-1 Ab group.Cytotoxic CD8^(+)T cells in TME were analyzed by flow cytometry.Results:Combining IR with AZD1775 synergistically reduced the viability of hepatoma cells in vitro.AZD1775 exhibited antitumor effects by decreasing CDK1 phosphorylation to reverse the IR-induced G2/M arrest and increasing IR-induced DNA damage.AZD1775 treatment also reduced the proportion of PD-1^(+)/CD8^(+)T cells in the spleen of hepatoma subcutaneous xenograft mice.Further studies revealed that AZD1775 and anti-PD-1 Ab could enhance the radiosensitivity of hepatoma by enhancing the levels of interferonγ(IFNγ)^(+)or Ki67^(+)CD8 T cells and decreasing the levels of CD8^(+)Tregs cells in the tumor and spleen of the hepatoma mice model,indicating that the improvement of TME was manifested by increasing the cytotoxic factor IFNγexpression,enhancing CD8^(+)T cells proliferation,and weakening CD8^(+)T cells depletion.Conclusions:This work suggests that AZD1775 and anti-PD-1 Ab synergistically sensitize hepatoma to radiotherapy by enhancing IR-induced DNA damage and improving cytotoxic CD8^(+)T cells in TME.

LncRNA NKILA inhibits HBV replication by repressing NF-κB signalling activation

Hepatitis B virus(HBV)infection results in liver cirrhosis and hepatocellular carcinoma(HCC).HBx/nuclear factor(NF)-κB pathway plays a role in HBV replication.However,whether NF-κB-interacting long noncoding RNA(NKILA),a suppressor of NF-κB activation,regulates HBV replication remains largely unknown.In this study,gain-and-loss experiments showed that NKILA inhibited HBV replication by inhibiting NF-κB activity.In turn,HBV infection down-regulated NKILA expression.In addition,expression levels of NKILA were lower in the peripheral blood-derived monocytes(PBMCs)of HBV-positive patients than in healthy individuals,which were correlated with HBV viral loads.And a negative correlation between NKILA expression level and HBV viral loads was observed in blood serum from HBV-positive patients.Lower levels of endogenous NKILA were also observed in HepG2 cells expressing a 1.3-fold HBV genome,HBV-infected HepG2-NTCP cells,stable HBV-producing HepG2.2.15 and HepAD38 cells,compared to those HBV-negative cells.Furthermore,HBx was required for NKILA-mediated inhibition on HBV replication.NKILA decreased HBx-induced NF-κB activation by interrupting the interaction between HBx and p65,whereas NKILA mutants lack of essential domains for NF-κB inhibition,lost the ability to inhibit HBV replication.Together,our data demonstrate that NKILA may serve as a suppressor of HBV replication via NF-κB signalling.

EV713C protease cleaves host anti-viral factor OAS3 and enhances virus replication

The global spread of enteroviruses(EVs)has become more frequent,severe and life-threatening.Intereron(IFN)I has been proved to control EVs by regulating IFN-stimulated genes(ISG)expression.20-50-oligoadenylate synthetases 3(OAS3)is an important ISG in the OAS/RNase L antiviral system.The relationship between OAS3 and EVs is still unclear.Here,we reveal that OAS3,superior to OAS1 and OAS2,significantly inhibited EV71 replication in vitro.However,EV71 utilized autologous 3C protease(3C^(pro))to cleave intracellular OAS3 and enhance viral replication.Rupintrivir,a human rhinovirus 3C protease inhibitor,completely abolished the cleavage of EV713C^(pro)on OAS3.And the proteolytically deficient mutants H40G,E71A,and C147G of EV713C^(pro)also lost the ability of OAS3 cleavage.Mechanistically,the Q982-G983 motif in C-terminal of OAS3 was identified as a crucial 3C^(pro)cutting site.Further investigation indicated that OAS3 inhibited not only EV71 but also Coxsackievirus B3(CVB3),Coxsackievirus A16(CA16),Enterovirus D68(EVD68),and Coxsackievirus A6(CA6)subtypes.Notably,unlike other four subtypes,CA163C^(pro)could not cleave OAS3.Two key amino acids variation Ile36 and Val86 in CA163C^(pro)might result in weak and delayed virus replication of CA16 because of failure of OAS and 3AB cleavage.Our works elucidate the broad anti-EVs function of OAS3,and illuminate a novel mechanism by which EV71 use 3C^(pro)to escape the antiviral effect of OAS3.These findings can be an important entry point for developing novel therapeutic strategies for multiple EVs infection.

IFN-β1b induces OAS3 to inhibit EV71 via IFN-β1b/JAK/STAT1 pathway

Enterovirus 71(EV71) caused hand, foot and mouth disease(HFMD) is a serious threat to the health of young children. Although type I interferon(IFN-I) has been proven to control EV71 replication, the key downstream IFNstimulated gene(ISG) remains to be clarified and investigated. Recently, we found that 2’-5’-oligoadenylate synthetases 3(OAS3), as one of ISG of IFN-β1b, was antagonized by EV71 3C protein. Here, we confirm that OAS3is the major determinant of IFN-β1b-mediated EV71 inhibition, which depends on the downstream constitutive RNase L activation. 2’-5’-oligoadenylate(2-5A) synthesis activity deficient mutations of OAS3 D816A, D818A,D888A, and K950A lost resistance to EV71 because they could not activate downstream RNase L. Further investigation proved that EV71 infection induced OAS3 but not RNase L expression by IFN pathway. Mechanically, EV71 or IFN-β1b-induced phosphorylation of STAT1, but not STAT3, initiated the transcription of OAS3 by directly binding to the OAS3 promoter. Our works elucidate the immune regulatory mechanism of the host OAS3/RNase L system against EV71 replication.

ATP1B3 Restricts Hepatitis B Virus Replication Via Reducing the Expression of the Envelope Proteins

Our recent study reported that ATP1B3 inhibits hepatitis B virus(HBV)replication via inducing NF-κB activation.However,ATP1B3 mutants which were defective in NF-κB activation still maintained the moderate degree of suppression on HBV replication,suggesting that another uncharacterized mechanism is also responsible for ATP1B3-mediated HBV suppression.Here,we demonstrated that ATP1B3 reduced the expression of HBV envelope proteins LHBs,MHBs and SHBs,but had no effect on intracellular HBV DNA,RNA levels as well as HBV promoter activities.Further investigation showed that proteasome inhibitor MG132 rescued ATP1B3-mediated envelope proteins degradation,demonstrating that proteasome-dependent pathway is involved in ATP1B3-induced degradation of envelope proteins.Co-IP showed that ATP1B3 interacts with LHBs and MHBs and induces LHBs and MHBs polyubiquitination.Immunofluorescence colocalization analysis confirmed LHBs and MHBs colocalized with ATP1B3 together.Our work provides important information for targeting ATP1B3 as a potential therapeutic molecule for HBV infection.

Deubiquitinase ubiquitin-specific protease 3 (USP3) inhibits HIV-1 replication via promoting APOBEC3G (A3G) expression in both enzyme activity-dependent and -independent manners

Background: Ubiquitination plays an essential role in many biological processes, including viral infection, and can be reversed by deubiquitinating enzymes (DUBs). Although some studies discovered that DUBs inhibit or enhance viral infection by various mechanisms, there is lack of information on the role of DUBs in virus regulation, which needs to be further investigated.Methods: Immunoblotting, real-time polymerase chain reaction,in vivo/in vitro deubiquitination, protein immunoprecipitation, immunofluorescence, and co-localization biological techniques were employed to examine the effect of ubiquitin-specific protease 3 (USP3) on APOBEC3G (A3G) stability and human immunodeficiency virus (HIV) replication. To analyse the relationship between USP3 and HIV disease progression, we recruited 20 HIV-infected patients to detect the levels of USP3 and A3G in peripheral blood and analysed their correlation with CD4^(+) T-cell counts. Correlation was estimated by Pearson correlation coefficients (for parametric data).Results: The results demonstrated that USP3 specifically inhibits HIV-1 replication in an A3G-dependent manner. Further investigation found that USP3 stabilized 90% to 95% of A3G expression by deubiquitinating Vif-mediated polyubiquitination and blocking its degradation in an enzyme-dependent manner. It also enhances the A3G messenger RNA (mRNA) level by binding to A3G mRNA and stabilizing it in an enzyme-independent manner. Moreover, USP3 expression was positively correlated with A3G expression (r= 0.5110) and CD4^(+) T-cell counts (r= 0.5083) in HIV-1-infected patients.Conclusions: USP3 restricts HIV-1 viral infections by increasing the expression of the antiviral factor A3G. Therefore, USP3 may be an important target for drug development and serve as a novel therapeutic strategy against viral infections.