Objective To rescue a recombinant oncolytic influenza virus chimeric with IL-21 and evaluate its inhibitory effects and safety against hepatocell ular carcinoma(HCC)both in vitro and in vivo,and to explore the mechanism by which this virus enhances antitumor effects when combined with anti-programmed cell death protein 1(anti-PD-1)antibody.Methods The IL-21 gene fragment was inserted into the nonstructural protein(NS)sequence of the influenza virus PR8 using reverse genetics(RG)technology to rescue the recombinant oncolytic influenza virus rOV-IL-21-NS.The virus titer and virulence were determined using the 50％tissue culture infectious dose(TCID50)and hemagglutination assays.The successful insertion of the exogenous gene into the NS sequence was verified using RT-qPCR,gel electrophoresis,and sequencing analysis.Viral morphology and size were observed with transmission electron microscopy.The impact of the virus on the viability of hepatocellular carcinoma cells was assessed with CCK-8 assay.A subcutaneous tumor model of HCC was established in 45 female C57BL/6 mice(8 weeks old,weighing 16～20 g),and then the mice were randomly assigned into PBS,PR8,anti-PD-1,rOV-IL-21-NS,and the rOV-IL-21-NS+anti-PD-1 treatment groups,with 9 mice in each group,to evaluate the anti-tumor effects of monotherapy versus combination therapy.Flow cytometry was conducted to assess the regulatory effects of monotherapy and combination therapy on the tumor immune microenvironment.Results RG technology successfully rescued the recombinant oncolytic influenza virus rOV-IL-21-NS.Sequencing confirmed the successful insertion of IL-21 into the target sequence,and the obtained virus could be stably propagated,with its sixth passage reaching a hemagglutination titer of 211,and a viral titer of 6 Log10(TCID50/mL).Oncolytic virus rOV-IL-21-NS,at a multiplicity of infection(MOI)of 3,selectively reduced the viability of HCC cells without significantly affecting normal liver cells.Compared to the control group,the combination of rOV-IL-21-NS and anti-PD-1 antibodies significantly inhibited tumor growth(P＜0.001)and increased the proportions of CD4+T and CD8+T cells in the spleen tissue of the mouse model of subcutaneous HCC tumor(P＜0.001).Conclusion The recombinant oncolytic influenza virus rOV-IL-21-NS chimeric with IL-21 can effectively and safely exert targeted killing to HCC cells,enhance T cell activation by synergizing with anti-PD-1 antibodies,and improve the immune microenvironment.

BACKGROUND: The switch/sucrose nonfermentable chromatin-remodeling (SWI/SNF) complex is a pivotal chromatin remodeling complex, and the genomic alterations (GAs) of the SWI/SNF complex are observed in several cancer types, correlating with multiple biological features of tumor cells. However, their role in liver metastasis of non-small cell lung cancer (NSCLC) remains unclear. Our study aims to investigate the role and potential mechanisms underlying NSCLC liver metastasis induced by the GAs of SWI/SNF complex. METHODS: The GAs of SWI/SNF complex in NSCLC cell lines (H1299, H23 and H460) were identified by whole-exome sequencing (WES). ARID1A knockout H1299 cell was constructed with the CRISPR/Cas9 technology. The mouse model of liver metastasis from NSCLC was established to simulate lung cancer liver metastasis and observe the metastasis rate under different gene mutation conditions. RNA sequencing and Western blot were conducted for differential gene expression analysis. Immunohistochemistry (IHC) analysis was used to assess protein expression levels of SWI/SNF-regulated target molecules in mouse liver metastases. RESULTS: WES analysis revealed intracellular gene mutations. The animal experiments demonstrated a correlation between the GAs of SWI/SNF complex and a higher liver metastasis rate in immunodeficient mice. Transcriptome sequencing and Western blot analysis showed upregulated expression of ALDH1A1 and APOBEC3B in SWI/SNF-mut cells, particularly in ARID1A-deficient H460 and H1299 sgARID1A cells. IHC staining of mouse liver metastases further demonstrated elevated expression of ALDH1A1 in the H460 and H1299 sgARID1A group. CONCLUSIONS This study underscores the critical role of the GAs of SWI/SNF complex, such as ARID1A and SMARCA4, in promoting liver metastasis of lung cancer cells. The GAs of SWI/SNF complex may promote liver-specific metastasis by upregulating ALDH1A1 and APOBEC3B expression, providing novel insights into the molecular mechanisms underlying lung cancer liver metastasis.
Animals ; Mice ; Carcinoma, Non-Small-Cell Lung/genetics* ; Lung Neoplasms/genetics* ; Mutation ; Liver Neoplasms/genetics*