Peixiang Lan

Histone deacetylase inhibitor SAHA epigenetically regulates miR-17-92 cluster and MCM7 to upregulate MICA expression in hepatoma.

Background:Epigenetic therapy using histone deacetylase inhibitors (HDACi) has shown promise in clinical trials for the treatment of human malignancies. In addition to the immediate effects on the tumour cell growth, HDACi upregulates the expression of MHC class I-related chain molecules A and B (MICA and MICB), resulting in an enhanced susceptibility of tumour cells to natural killer cell-mediated lysis. The molecular mechanism underlying is still unclear.Methods:The transcriptional regulation mechanism underlying suberoylanilide hydroxamic acid (SAHA)-mediated regulation of MICA and related miRNA expression was investigated using promoter acetylation assays, bioinformatics analysis and chromatin immunoprecipitation assay.Results:SAHA upregulates the transcription of MICA/B by promoting MICA-associated histone acetylation while suppressing the MICA/B-targeting miRNAs miR-20a, miR-93 and miR-106b. The mechanism by which SAHA repressed miRNAs transcription involved repression of their host genes (miR-17-92 cluster and MCM7). SAHA downregulated the miR-17-92 cluster by abolishing tyrosine phosphorylation of STAT3 and decreased MCM7 transcription through localised histone deacetylation.Conclusions:The HDACi SAHA epigenetically upregulates MICA expression through regulating the expression of miR-17-92 cluster and MCM7 in hepatoma, thus enhancing the sensitivity of HCC to natural killer cell-mediated lysis. This novel mechanism of action provides promise for HDACi in therapy of HCC.

Therapeutic recovery of hepatitis B virus (HBV)-induced hepatocyte-intrinsic immune defect reverses systemic adaptive immune tolerance†‡

Hepatitis B virus (HBV) persistence aggravates hepatic immunotolerance, leading to the failure of cell‐intrinsic type I interferon and antiviral response, but whether and how HBV‐induced hepatocyte‐intrinsic tolerance influences systemic adaptive immunity has never been reported, which is becoming the major obstacle for chronic HBV therapy. In this study, an HBV‐persistent mouse, established by hydrodynamic injection of an HBV‐genome‐containing plasmid, exhibited not only hepatocyte‐intrinsic but also systemic immunotolerance to HBV rechallenge. HBV‐specific CD8+ T‐cell and anti‐HBs antibody generation were systemically impaired by HBV persistence in hepatocytes. Interestingly, HBV‐induced hepatocyte‐intrinsic immune tolerance was reversed when a dually functional vector containing both an immunostimulating single‐stranded RNA (ssRNA) and an HBx‐silencing short hairpin RNA (shRNA) was administered, and the systemic anti‐HBV adaptive immune responses, including CD8+ T‐cell and anti‐HBs antibody responses, were efficiently recovered. During this process, CD8+ T cells and interferon‐gamma (IFN‐γ) secreted play a critical role in clearance of HBV. However, when IFN‐α/β receptor was blocked or the Toll‐like receptor (TLR)7 signaling pathway was inhibited, the activation of CD8+ T cells and clearance of HBV was significantly impaired. Conclusion: These results suggest that recovery of HBV‐impaired hepatocyte‐intrinsic innate immunity by the dually functional vector might overcome systemic adaptive immunotolerance in an IFN‐α‐ and TLR7‐dependent manner. The strategy holds promise for therapeutic intervention of chronic persistent virus infection and associated cancers. (Hepatology 2013;)

HBV inhibits LPS-induced NLRP3 inflammasome activation and IL-1β production via suppressing the NF-κB pathway and ROS production

BACKGROUND & AIMS Hepatitis B virus (HBV) has developed strategies to evade immune responses. However, the mechanisms involved remain unclear. The NLRP3 inflammasome plays crucial roles in antiviral host defense and its downstream factor IL-1β has been shown to inhibit HBV infection in vivo. This study aims to assess whether HBV can affect the NLRP3 inflammasome signaling pathways and shed light on the underlying mechanisms HBV utilizes to evade host innate immune responses. METHODS HBV inhibition of the lipopolysaccharide (LPS)-induced NLRP3 inflammasome activation was evaluated by Western blot, quantitative RT-PCR, flow cytometry and immunofluorescence. RESULTS Kupffer cells expressed significantly more NLRP3 and IL-1β after LPS stimulation; whereas, chronic HBV infection suppressed LPS-induced NLRP3 and pro-IL-1β expression as well as IL-1β maturation. This inhibitory activity is mediated by HBeAg, and is involved in the inhibition of NF-κB signal pathway and reactive oxygen species (ROS) production. The inhibitory effect of HBeAg was confirmed in patients with chronic hepatitis B (CHB) and hepatocellular carcinoma by comparing the levels of IL-1β and NLRP3-related proteins in para-carcinoma tissues from HBeAg-positive or negative patients. Moreover, chronic HBV infection increases the susceptibility of mice to S. typhimurium infection, possibly via inhibiting the NLRP3 inflammasome activation and IL-1β production. CONCLUSIONS HBeAg inhibits LPS-induced NLRP3 inflammasome activation and IL-1β production via suppressing NF-κB pathway and ROS production. This finding provides a novel mechanism for HBV-mediated suppression of innate immune responses, and identifies new therapeutic targets for chronic HBV infection and related diseases. LAY SUMMARY HBeAg suppresses LPS-induced NLRP3 inflammasome activation and IL-1β production in two ways, one is to repress NLRP3 and pro-IL-1β expression via inhibiting NF-κB phosphorylation, and the other is to repress caspase-1 activation and IL-1β maturation via inhibiting ROS production. This effect contributes to the HBV persistence and immune tolerance.

Immunotherapy for Hepatoma Using a Dual-Function Vector with Both Immunostimulatory and Pim-3–Silencing Effects

Tumorigenesis is an immortalization process in which the growth of normal cells is uncontrolled and programmed cell death is suppressed. Molecular biologic and immunologic studies have revealed that the aberrant expression of some proto-oncogenes boosts proliferation and inhibits apoptosis, which is vital for tumor development. The hypofunction of the host immune system also drives the development and metastasis of malignant tumors. Pim-3, a member of the Pim family, is aberrantly expressed in several cancers. Data suggest that Pim-3 inhibits apoptosis by phosphorylating the proapoptotic BH3-only protein Bad. Here, we constructed a dual-function small hairpin RNA (shRNA) vector containing an shRNA targeting Pim-3 and a TLR7-stimulating ssRNA. Stimulation with this bi-functional vector in vitro promoted significant apoptosis of Hepa1-6 cells by regulating the expression of apoptosis-related proteins and induced secretion of type I IFNs. Most importantly, this bi-functional vector more effectively inhibited subcutaneous Hepa1-6 cell growth than did single shRNA and ssRNA treatment in vivo. Natural killer (NK), CD4+ T, and CD8+ T cells and macrophages were required for effective tumor suppression, and CD4+ T cells were shown to play a helper role in the activation of NK cells, possibly by regulating the secretion of Th1 or Th2 cytokines. This ssRNA–shRNA bi-functional vector may represent a promising approach for tumor therapy. Mol Cancer Ther; 13(6); 1503–13. ©2014 AACR.

Reversal of hepatitis B virus‐induced systemic immune tolerance by intrinsic innate immune stimulation

Systemic immune tolerance induced by chronic hepatitis B virus (HBV) infection is a significant question, but the mechanism of which remains unclear. In this mini-review, we summarize the impaired innate and adaptive immune responses involved in immune tolerance in chronic HBV infection. Furthermore, we delineate a novel dual functional small RNA to inhibit HBV replication and stimulate innate immunity against HBV, which proposed a promising immunotherapeutic intervention to interrupt HBV-induced immunotolerance. A mouse model of HBV persistence was established and used to observe the immune tolerant to HBV vaccination, the cell-intrinsic immune tolerance of which might be reversed by chemically synthesized dual functional small RNA (3p-hepatitis B Virus X gene [HBx]-small interfering RNA) in vitro experiments and by biologically constructed dual functional vector (single-stranded RNA-HBx- short hairpin RNA) in vivo experiment using HBV-carrier mice.

Superior activity of a new histone deacetylase inhibitor (ZYJ-34c) in inhibiting growth of human leukemia cells by inducing p21WAF1 expression and cell cycle arrest.

Histone deacetylase inhibitors are a new class of anticancer agents that inhibit cancer cell proliferation and induce apoptosis and cell cycle arrest in various cancer cells. Recently, we identified ZYJ-34c, a modified histone deacetylase inhibitor that showed significantly higher antitumor activity in vivo than the FDA-approved drug suberoylanilide hydroxamic acid. We aimed to investigate its exact mechanism of action. Activity of ZY-34c against human erythroleukemic (K562) cells, human myeloid leukemia (HL-60) cells, and primary leukemic cells were investigated in vitro using proliferation assays, cell cycle assays, apoptosis assays, RNA interference, promoter acetylation assays, and assays of transcription of related molecules. ZYJ-34c strongly inhibited the proliferation of leukemia cells compared with suberoylanilide hydroxamic acid. Primary leukemic cells isolated from patients with acute myeloid leukemia were more sensitive to ZYJ-34c. The 50% growth-inhibitory concentrations of ZYJ-34c and suberoylanilide hydroxamic acid were 2.95±0.75 and 4.45±0.29 &mgr;mol/l for K562 cells treated for 48 h, respectively. We found that ZYJ-34c caused more significant G1 cell cycle arrest than suberoylanilide hydroxamic acid, in a time-dependent manner. ZYJ-34c-induced hyperacetylation of histone H3 and H4 around the promoter region of p21WAF1. P21 RNA interference markedly impaired ZYJ-34c-induced or suberoylanilide hydroxamic acid-induced G1 cell cycle arrest. In addition, levels of bcr-abl mRNA and protein in K562 cells decreased after treatment with either suberoylanilide hydroxamic acid or ZYJ-34c; moreover, ZYJ-34c had a higher inhibition activity. ZYJ-34c could represent a novel pharmacological agent with potential benefit for patients with leukemia.

HBV suppresses expression of MICA/B on hepatoma cells through up-regulation of transcription factors GATA2 and GATA3 to escape from NK cell surveillance

Decreased expression of NKG2D ligands on HBV-infected human hepatoma cells impairs NK cells lysis. However, which components of HBV exert this effect and the precise mechanisms need to be further investigated. In the present study, we observed that the HBx and HBc genes significantly down-regulated MICA expression. Through analysis with the chromatin immunoprecipitation assay, we found that HBV infection promotes the expression of transcription factors GATA-2 and GATA-3, which specifically suppressed MICA/B expression by directly binding to the promoter region of MICA/B. HBx protein, acting as a co-regulator, forms a tripolymer with GATA2 and GATA3, thus promotes the GATA-2 or GATA-3-mediated of MICA/B suppression. HBc protein inhibits MICA/B expression via directly binding to the CpG island in the MICA/B promoter. Thus, our study identified the novel role of transcription factors GATA-2 and GATA-3 in suppressing MICA/B expression and clarified the mechanisms of HBx and HBc in downregulation of MICA/B expression. These findings provide novel mechanisms for the contribution of HBV to hepatoma cells escape from NK cell surveillance.

Oncofetal gene SALL4 reactivation by hepatitis B virus counteracts miR-200c in PD-L1-induced T cell exhaustion.

A chronic viral or tumor microenvironment can push T cells to exhaustion by promoting coinhibitory ligand expression. However, how host factors control coinhibitory ligand expression and whether viral infection breaks this control during tumor progress is unknown. Here we show a close negative correlation between SALL4 or PD-L1 and miR-200c in tumors from 98 patients with HBV-related hepatocellular carcinoma. SALL4 or PD-L1 expression correlates negatively with miR-200c expression, and patients with lower levels of SALL4 or PD-L1 and higher miR-200c survive longer. Moreover, over-expression of miR-200c antagonizes HBV-mediated PD-L1 expression by targeting 3ʹ-UTR of CD274 (encoding PD-L1) directly, and reverses antiviral CD8+ T cell exhaustion. MiR-200c transcription is inhibited by oncofetal protein SALL4, which is re-expressed through HBV-induced STAT3 activation in adulthood. We propose that an HBV-pSTAT3-SALL4-miR-200c axis regulates PD-L1. Therapeutic strategies to influence this axis might reverse virus-induced immune exhaustion.Blocking PD-1 function on T cells is thought to be a viable strategy to prevent virus-induced or tumor-induced T cell exhaustion. Here the authors link the zinc-finger transcription factor SALL4 with miR-200c inhibition of PD-L1 expression by hepatocytes in patients with HBV-induced hepatocellular carcinoma.

Pim-3 enhances melanoma cell migration and invasion by promoting STAT3 phosphorylation

ABSTRACT Melanoma is the deadliest form of commonly encountered skin cancer, and has fast propagating and highly invasive characteristics. Pim-3, a highly expressed oncogene in melanoma, is a highly conserved serine/threonine kinase with various biological activities, such as proliferation-accelerating and anti-apoptosis effects on cancer progression. However, whether Pim-3 regulates melanoma metastasis has not been determined. Here, we constructed a Pim-3–silencing short hairpin RNA (sh-Pim-3), a TLR7-stimulating ssRNA and a dual-function vector containing a sh-Pim-3 and a ssRNA, and transfected them into the B16F10 melanoma cell line to investigate the effects of Pim-3 on migration and invasion in melanoma. We found that sh-Pim-3 inhibited B16F10 cell migration and invasion in vitro. In a tumor-bearing mouse model, sh-Pim-3 significantly downregulated pulmonary metastasis of B16F10 melanoma cell in vivo. Mechanistically, sh-Pim-3 inhibited metastasis by regulating the expression of genes related to epithelial–mesenchymal transition (EMT). Further study revealed that by promoting the phosphorylation of STAT3 (signal transducer and activator of transcription 3), Pim-3 induced the expression of Slug, Snail, and ZEB1, which enhanced EMT-related changes and induced melanoma migration and invasion. Our study suggests that Pim-3 is a potential effective target for melanoma therapy.