GII.P16-GII.2 Recombinant Norovirus VLPs Polarize Macrophages Into the M1 Phenotype for Th1 Immune Responses.

Norovirus (NoV) is a zoonotic virus that causes diarrhea in humans and animals. Outbreaks in nosocomial settings occur annually worldwide, endangering public health and causing serious social and economic burdens. The latter quarter of 2016 witnessed the emergence of the GII.P16-GII.2 recombinant norovirus throughout Asia. This genotype exhibits strong infectivity and replication characteristics, proposing its potential to initiate a pandemic. There is no vaccine against GII.P16-GII.2 recombinant norovirus, so it is necessary to design a preventive vaccine. In this study, GII.P16-GII.2 type norovirus virus-like particles (VLPs) were constructed using the baculovirus expression system and used to conduct immunizations in mice. After immunization of mice, mice were induced to produce memory T cells and specific antibodies, indicating that the VLPs induced specific cellular and humoral immune responses. Further experiments were then initiated to understand the underlying mechanisms involved in antigen presentation. Towards this, we established co-cultures between dendritic cells (DCs) or macrophages (Mø) and naïve CD4+T cells and simulated the antigen presentation process by incubation with VLPs. Thereafter, we detected changes in cell surface molecules, cytokines and related proteins. The results indicated that VLPs effectively promoted the phenotypic maturation of Mø but not DCs, as indicated by significant changes in the expression of MHC-II, costimulatory factors and related cytokines in Mø. Moreover, we found VLPs caused Mø to polarize to the M1 type and release inflammatory cytokines, thereby inducing naïve CD4+ T cells to perform Th1 immune responses. Therefore, this study reveals the mechanism of antigen presentation involving GII.P16-GII.2 recombinant norovirus VLPs, providing a theoretical basis for both understanding responses to norovirus infection as well as opportunities for vaccine development.

Autophagy promotes oncolysis of an adenovirus expressing apoptin in human bladder cancer models.

As a potential cancer therapy, we developed a recombinant adenovirus named Ad-VT, which was designed to express the apoptosis-inducing gene (apoptin) and selectively replicate in cancer cells via E1a manipulation. However, how it performs in bladder cancer remains unclear. We examined the antitumor efficacy of Ad-VT in bladder cancers using CCK-8 assays and xenograft models. Autophagy levels were evaluated by western blotting, MDC staining, and RFP-GFP-LC3 aggregates' analyses. Here, we report the selective replication and antitumor efficacy (viability inhibition and apoptosis induction) of Ad-VT in bladder cancer cells. Using xenograft tumor models, we demonstrate that its effects are tumor specific resulting in the inhibition of tumor growth and improvement of the survival of mice models. Most Importantly, Ad-VT induced a complete autophagy flux leading to autophagic cancer cell death through a signaling pathway involving AMPK, raptor and mTOR. Finally, we suggest that treatment combination of Ad-VT and rapamycin results in a synergistic improvement of tumor control and survival compared to monotherapy. This study suggests that Ad-VT can induce selective autophagic antitumor activities in bladder cancer through the AMPK-Raptor-mTOR pathway, which can be further improved by rapamycin.

Recombinant adenoviruses expressing apoptin suppress the growth of MCF­7 breast cancer cells and affect cell autophagy.

Autophagy and apoptosis both promote cell death; however, the relationship between them is subtle, and they mutually promote and antagonize each other. Apoptin can induce apoptosis of various tumor cells; however, tumor cell death is not only caused by apoptosis. Whether apoptin affects tumor cell autophagy is poorly understood. Therefore, the present study aimed to explore the potential mechanisms underlying the effects of apoptin using recombinant adenoviruses expressing apoptin. Reverse transcription­quantitative polymerase chain reaction, immunoblotting, flow cytometry, fluorescence microscopy and proteomics analyses revealed that apoptin could induce autophagy in MCF­7 breast cancer cells. The results also suggested that apoptin affected autophagy in a time­ and dose­dependent manner. During the early stage of apoptin stimulation (6 and 12 h), the expression levels of autophagy pathway­associated proteins, including Beclin­1, microtubule­associated protein 1A/1B­light chain 3, autophagy­related 4B cysteine peptidase and autophagy­related 5, were significantly increased, suggesting that apoptin promoted the upregulation of autophagy in MCF­7 cells. Conversely, after 12 h of apoptin stimulation, the expression levels of apoptosis­associated proteins were decreased, thus suggesting that apoptosis may be inhibited. Therefore, it was hypothesized that apoptin may enhance autophagy and inhibit apoptosis in MCF­7 cells at the early stage. In conclusion, apoptin­induced cell death may involve both autophagy and apoptosis. The induction of autophagy may inhibit apoptosis, whereas apoptosis may inhibit autophagy; however, occasionally both pathways operate at the same time and involve apoptin. This apoptin­associated selection between tumor cell survival and death may provide a potential therapeutic strategy for breast cancer.

Antitumor effect of a dual cancer-specific oncolytic adenovirus on prostate cancer PC-3 cells.

PURPOSE: Apoptin can specifically kill cancer cells but has no toxicity to normal cells. Human telomerase reverse transcriptase (hTERT) acts as a tumor-specific promoter, triggering certain genes to replicate or express only in tumor cells, conferring specific replication and killing abilities. This study aimed to investigate the anticancer potential of the recombinant adenovirus Ad-apoptin-hTERTp-E1a (Ad-VT) in prostate cancer. METHODS: The pGL4.51 plasmid was used to transfect PC-3 cells to construct tumor cells stably expressing luciferase (PC-3-luc). Crystal violet staining and MTS assays determined the ability of Ad-VT to inhibit cell proliferation. Ad-VT-induced apoptosis of PC-3-luc cells was detected using Hoechst, Annexin V, JC-1 staining, and caspases activity analysis. PC-3-luc cells invasion and migration were detected using cell-scratch and Transwell assays. In vivo tumor inhibition was detected using imaging techniques. RESULTS: Crystal violet staining and MTS results showed that the proliferation ability of PC-3-luc cells decreased significantly. Hoechst, JC-1, and Annexin V experiments demonstrated that Ad-VT mainly induced apoptosis to inhibit PC-3-luc cell proliferation. Ad-VT could significantly inhibit the migration and invasion of PC-3-luc cells over a short period of time. In vivo, Ad-VT could effectively inhibit tumor growth and prolong survival of the mice. CONCLUSIONS: The recombinant adenovirus, comprising the apoptin protein and the hTERTp promoter, was able to inhibit the growth of prostate cancer PC-3 cells and promote their apoptosis.