Zhihua Ruan

DNA Vaccine Against Tumor Endothelial Marker 8 Inhibits Tumor Angiogenesis and Growth

Numerous evidences indicated that angiogenesis was a crucial step in the development of tumor, thus the immunotherapy of antiangiogenesis has been involved as potentially relevant candidate targets of cancer immunotherapy. Recently, tumor endothelial marker 8 (TEM8) was discovered to be dominantly expressed in tumor endothelium, which presented a new strategy to antiangiogenesis therapy. However, up to date, the related study of TEM8 on antiangiogenesis is very few. In this study, we constructed a xenogenic DNA vaccine encoding human TEM8 carried by attenuated Salmonella typhimurium. The results demonstrated that oral administration of this xenogenic vaccine overcame peripheral immune tolerance and generated TEM8-specific CD8+ cytotoxic T-cell response. Moreover, this vaccine effectively protected mice from lethal challenges against tumor cells, reducing tumor growth, and increasing the mice life span. In addition, angiogenesis in the tumors was suppressed without obvious side effect. These results indicated that DNA vaccine encoding xenogenic TEM8 might act as a potential strategy for antiangiogenesis immunotherapy of tumors.

Tumor-derived soluble MICs impair CD3(+)CD56(+) NKT-like cell cytotoxicity in cancer patients.

Upon ligation with its ligands, the activating receptor NKG2D stimulates or costimulates CD8(+) T cells or NK cells. The inducible gene MHC class I chain-related molecules (MICs), which belong to the NKG2D ligand family and usually initiate the process of lymphocyte activation, have been found to be broadly expressed on epithelial tumor cells. Sustained localized expression or release of soluble forms of MICs (sMICs) by tumor cells play key roles in tumor evasion via the impairment of T cell and NK cell functions. NKG2D is also expressed on the surface of CD3(+)CD56(+) NKT-like cells, which participate in tumor rejection via direct cytolysis. We speculated whether sMICs have the same impact on NKT-like cells. In this study, we demonstrated that in vitro killing by freshly isolated NKT-like cells was principally mediated by NKG2D, and the cytotoxic function of NKT-like cells isolated from cancer patients was obviously compromised. We found a significant correlation between elevated tumor-derived sMICs and down-modulation of NKG2D expression on NKT-like cell surfaces in human ovarian cancer and prostate cancer patients. We determined that elevated serum sMIC impairs the lytic activity via downregulation of the NKG2D receptor because incubation of NKT-like cells with sera obtained from cancer patients down-modulated surface NKG2D expression, whereas the addition of neutralizing anti-MIC mAbs restored surface NKG2D expression. We suggest that tumors shedding MICs may promote immune evasion by impairing NKT-like cell cytotoxicity.

ERCC5 promoter polymorphisms at -763 and +25 predict the response to oxaliplatin-based chemotherapy in patients with advanced colorectal cancer

2 This study aimed to investigate whether single nucleotide polymorphisms (SNPs) in the promoter of the excision repair cross complementation group 5 (ERCC5) gene influences response to oxaliplatin-based chemotherapy. Eighty-three patients with cytologically or histologically confirmed advanced colorectal cancer (CRC), at least one measurable lesion and underwent oxaliplatin-based chemotherapy were studied. To this end, six polymorphisms (-1415C>T, -763A>G, -413C>T, +25A>G, +202C>T, +372C>T) in the ERCC5 promoter were selected for investigation. Genomic DNA was obtained from peripheral blood cells, and polymerase chain reaction-ligation detection reaction was used to analyze these SNPs. The χ2 test or Fisher’s exact test was then used to investigate the association between polymorphisms and chemotherapy response. Our results showed that the response rate among patients with the -763GG genotype (72.7%) was significantly higher than that of other genotypes (22.2% for AA genotype, P=0.008 and 37.2% for AG genotype, P=0.046 respectively). In addition, the response rate among patients with the +25AA genotype (75%) was significantly higher than that of other genotypes (24.1% for GG genotype, P=0.004 and 35.7% for AG genotype, P=0.022 respectively). Patients with the -763A/+25G haplotype had a higher risk of non-response to oxaliplatin chemotherapy compared to those carrying the -763G/+25A haplotype (OR 2.672, 95% CI 1.353-5.278, P=0.004). However, no genetic variation was observed at site -413, and no significant association was found between the -1415C>T, +202C>T or +372C>T polymorphisms and chemotherapy response. Therefore, these data suggest that ERCC5 promoter polymorphisms at -763 and +25 may be important predictors of response to oxaliplatin chemotherapy.

Induced B7-H1 expression on human renal tubular epithelial cells by the sublytic terminal complement complex C5b-9.

The co-inhibitory molecule B7-H1 has been broadly detectable on human inflammatory renal tubular epithelial cells (TECs) and is proposed to limit tubular damage through down-regulation of tubulointerstitial infiltration T cell activation. Nevertheless, factors that initiate B7-H1 expression on TECs remain unclarified. The terminal complement complex C5b-9, which deposits diffusely on tubules and glomerules of diseased kidneys, is now recognized as a mediator that triggers cellular activation rather than inducing cell death. Whether the up-regulation of B7-H1 on tubules is also induced by C5b-9 is uncertain. Here, after assembling functional sublytic C5b-9 on the membranes of TECs based on purified complement components, we found that B7-H1 gene transcription and protein synthesis was enhanced by C5b-9. Promoter constructs in a luciferase assay, site-directed mutagenesis and laser scanning confocal microscopy assay (LSCM) revealed that the transcription factor NF-kappaB is primarily responsible for C5b-9-mediated B7-H1 expression. To further detect the physiologic function of B7-H1, triggering B7-H1 with its agonist mAb (clone 5H1) profoundly enhanced Fas expression on C5b-9-treated TECs and thus induced TEC apoptosis. Interestingly, pretreatment of TECs with Fas blocking antibodies prevented this effect. Our results propose that C5b-9 regulates tubular pathogenesis in glomerulonephritis or other renal autoimmune diseases, possibly through enhances cell apoptosis mediated by B7-H1 signals, in addition to it directly promotes tubular damage.

Macrophage ABHD5 promotes colorectal cancer growth by suppressing spermidine production by SRM

Metabolic reprogramming in stromal cells plays an essential role in regulating tumour growth. The metabolic activities of tumour-associated macrophages (TAMs) in colorectal cancer (CRC) are incompletely characterized. Here, we identify TAM-derived factors and their roles in the development of CRC. We demonstrate that ABHD5, a lipolytic co-activator, is ectopically expressed in CRC-associated macrophages. We demonstrate in vitro and in mouse models that macrophage ABHD5 potentiates growth of CRC cells. Mechanistically, ABHD5 suppresses spermidine synthase (SRM)-dependent spermidine production in macrophages by inhibiting the reactive oxygen species-dependent expression of C/EBPɛ, which activates transcription of the srm gene. Notably, macrophage-specific ABHD5 transgene-induced CRC growth in mice can be prevented by an additional SRM transgene in macrophages. Altogether, our results show that the lipolytic factor ABHD5 suppresses SRM-dependent spermidine production in TAMs and potentiates the growth of CRC. The ABHD5/SRM/spermidine axis in TAMs might represent a potential target for therapy.

Identification of a new HLA-A*0201-restricted cytotoxic T lymphocyte epitope from CML28

Identification of cytotoxic T lymphocyte (CTL) epitopes from additional tumor antigens is essential for the development of specific immunotherapy of malignant tumors. CML28, a recently discovered cancer-testis (CT) antigen from chronic myelogenous leukemia, is considered to be a promising target of tumor-specific immunotherapy. Because HLA-A*0201 is one of the most common histocompatibility molecule in Chinese, we aim at identifying CML28 peptides presented by HLA-A*0201. A panel of CML28-derived antigenic peptides was predicted using a computer-based program. Four peptides with highest predicted score were synthesized and tested for their binding affinities to HLA-A*0201 molecule. Then these peptides were assessed for their immunogenicity to elicit specific immune responses mediated by CTLs both in vitro, from PBMCs sourced from four healthy HLA-A*0201+ donors, and in vivo, in HLA-A*0201 transgenic mice. One of the tested peptides, CML28(173–181), induced peptide-specific CTLs in vitro as well as in vivo, which could specifically secrete IFN-γ and lyse major histocompatibility complex (MHC)-matched tumor cell lines endogenously expressing CML28 antigen and CML28(173–181) pulsed Jurkat-A2/Kb cells, respectively. These results demonstrate that CML28(173–181) is a naturally processed and presented CTL epitope with HLA-A*0201 motif and has a promising immunogenicity both in vitro and in vivo. As CML28 is expressed in a large variety of histological tumors besides chronic myelogenous leukemia, we propose that the newly identified epitope, CML28(173–181), would be of potential use in peptide-based, cancer-specific immunotherapy against a broad spectrum of tumors.

Stearic acid induces proinflammatory cytokine production partly through activation of lactate-HIF1α pathway in chondrocytes.

The biomechanics stress and chronic inflammation in obesity are causally linked to osteoarthritis. However, the metabolic factors mediating obesity-related osteoarthritis are still obscure. Here we scanned and identified at least two elevated metabolites (stearic acid and lactate) from the plasma of diet-induced obese mice. We found that stearic acid potentiated LDH-a-dependent production of lactate, which further stabilized HIF1α protein and increased VEGF and proinflammatory cytokine expression in primary mouse chondrocytes. Treatment with LDH-a and HIF1α inhibitors notably attenuated stearic acid-or high fat diet-stimulated proinflammatory cytokine production in vitro and in vivo. Furthermore, positive correlation of plasma lactate, cartilage HIF1α and cytokine levels with the body mass index was observed in subjects with osteoarthritis. In conclusion, saturated free fatty acid induced proinflammatory cytokine production partly through activation of a novel lactate-HIF1α pathway in chondrocytes. Our findings hold promise of developing novel clinical strategies for the management of obesity-related diseases such as osteoarthritis.

Melatonin regulates PARP1 to control the senescence‐associated secretory phenotype (SASP) in human fetal lung fibroblast cells

Cellular senescence is an important tumor‐suppressive mechanism. However, acquisition of a senescence‐associated secretory phenotype (SASP) in senescent cells has deleterious effects on the tissue microenvironment and, paradoxically, promotes tumor progression. In a drug screen, we identified melatonin as a novel SASP suppressor in human cells. Strikingly, melatonin blunts global SASP gene expression upon oncogene‐induced senescence (OIS). Moreover, poly(ADP‐ribose) polymerase‐1 (PARP‐1), a sensor of DNA damage, was identified as a new melatonin‐dependent regulator of SASP gene induction upon OIS. Here, we report two different but potentially coherent epigenetic strategies for melatonin regulation of SASP. The interaction between the telomeric repeat‐containing RNA (TERRA) and PARP‐1 stimulates the SASP, which was attenuated by 67.9% (illustrated by the case of IL8) by treatment with melatonin. Through binding to macroH2A1.1, PARP‐1 recruits CREB‐binding protein (CBP) to mediate acetylation of H2BK120, which positively regulates the expression of target SASP genes, and this process is interrupted by melatonin. Consequently, the findings provide novel insight into melatonins epigenetic role via modulating PARP‐1 in suppression of SASP gene expression in OIS‐induced senescent cells. Our studies identify melatonin as a novel anti‐SASP molecule, define PARP‐1 as a new target by which melatonin regulates SASP, and establish a new epigenetic paradigm for a pharmacological mechanism by which melatonin interrupts PARP‐1 interaction with the telomeric long noncoding RNA(lncRNA) or chromatin.

Intrahepatic Expression of Programmed Death-1 and its Ligands in Patients with HBV-Related Acute-on-Chronic Liver Failure

Hepatitis B virus (HBV) infection is a major public health problem, and HBV-related acute-on-chronic liver failure (HBV-ACLF) has an extremely poor prognosis due to a lack of understanding of pathogenesis as well as a lack of effective treatments. Signals from the inhibitory receptor programmed death-1 (PD-1) have been demonstrated to be involved in regulating the pathogenesis of infectious diseases. However, the expression of PD-1 and its ligands in HBV-ACLF patients has yet to be evaluated. In this study, the expression of PD-1 and its ligands, PD-L1 and PD-L2, in liver biopsies from HBV-ACLF as well as chronic hepatitis B (CHB) patients were analyzed by immunohistochemistry. The results showed that all three molecules were observed in the HBV-ACLF samples and their levels were significantly higher than they were in CHB. Immunofluorescence double-staining showed that PD-1 was found on CD3+, CD8+ T cells, CD56+ NK cells, CD68+ macrophages, CK-18+ epithelial cells, and CD16+ monocytes. The PD-L1 expression was observed on all cell types detected and the PD-L2 was chiefly on CK-18+ epithelial cells and CD31+ endothelial cells. Interestingly, high levels of virus-induced procoagulant molecule fibrinogen-like protein 2 (FGL2) were observed in liver sections from HBV-ACLF, and PD-L1 and PD-L2 expression was also observed on FGL2+ cells in these patients. Our combined results suggest that the expression of PD-L1 and PD-L2 may be biomarkers to identify and diagnose ACLF, and a clear understanding of their functional roles should further elucidate the pathogenesis of this disease.

Macrophages induce resistance to 5-fluorouracil chemotherapy in colorectal cancer through the release of putrescine

The development of chemoresistance to 5-fluorouracil (5-FU) is a major obstacle for sustained effective treatment of colorectal cancer (CRC), with the mechanisms being not fully understood. Here we demonstrated that tumor associated macrophages (TAMs) became activated during treatment with 5-FU and secreted factors that protected the CRC cells against chemotherapy with 5-FU. By performing metabolomics analysis, we identified putrescine, a member of polyamines, inducing resistance to 5-FU-triggered CRC apoptosis and tumor suppression via JNK-caspase-3 pathway. Noteworthily, either pharmacological or genetic blockage of ornithine decarboxylase (ODC) prevented TAMs-induced chemoresistance to 5-FU in vitro and in vivo. Our findings show that TAMs are potent mediators of resistance to 5-FU chemotherapy and uncover potential targets to enhance chemotherapy sensitivity in patients with CRC.