Nicotine stimulated dendritic cells could achieve anti-tumor effects in mouse lung and liver cancer

Potential of Compounds Originating from the Nature to Act in Hepatocellular Carcinoma Therapy by Targeting the Tumor Immunosuppressive Microenvironment: A Review

Hepatocellular carcinoma (HCC), the most prevalent subtype of liver cancer, is the second main reason for cancer-related deaths worldwide. In recent decades, sufficient evidence supported that immunotherapy was a safe and effective treatment option for HCC. However, tolerance and frequent recurrence and metastasis occurred in patients after immunotherapy due to the complicated crosstalk in the tumor immunosuppressive microenvironment (TIME) in HCC. Therefore, elucidating the TIME in HCC and finding novel modulators to target TIME for attenuating immune suppression is critical to optimize immunotherapy. Recently, studies have shown the potentially immunoregulatory activities of natural compounds, characterized by multiple targets and pathways and low toxicity. In this review, we concluded the unique role of TIME in HCC. Moreover, we summarized evidence that supports the hypothesis of natural compounds to target TIME to improve immunotherapy. Furthermore, we discussed the comprehensive mechanisms of these natural compounds in the immunotherapy of HCC. Accordingly, we present a well-grounded review of the naturally occurring compounds in cancer immunotherapy, expecting to shed new light on discovering novel anti-HCC immunomodulatory drugs from natural sources.

Reduced Chronic Toxicity and Carcinogenicity in A/J Mice in Response to Life-Time Exposure to Aerosol From a Heated Tobacco Product Compared With Cigarette Smoke

We conducted an inhalation study, in accordance with Organisation for Economic Co-operation and Development Test Guideline 453, exposing A/J mice to tobacco heating system (THS) 2.2 aerosol or 3R4F reference cigarette smoke (CS) for up to 18 months to evaluate chronic toxicity and carcinogenicity. All exposed mice showed lower thymus and spleen weight, blood lymphocyte counts, and serum lipid concentrations than sham mice, most likely because of stress and/or nicotine effects. Unlike THS 2.2 aerosol-exposed mice, CS-exposed mice showed increased heart weight, changes in red blood cell profiles and serum liver function parameters. Similarly, increased pulmonary inflammation, altered lung function, and emphysematous changes were observed only in CS-exposed mice. Histopathological changes in other respiratory tract organs were significantly lower in the THS 2.2 aerosol-exposed groups than in the CS-exposed group. Chronic exposure to THS 2.2 aerosol also did not increase the incidence or multiplicity of bronchioloalveolar adenomas or carcinomas relative to sham, whereas CS exposure did. Male THS 2.2 aerosol-exposed mice had a lower survival rate than sham mice, related to an increased incidence of urogenital issues that appears to be related to congenital factors rather than test item exposure. The lower impact of THS 2.2 aerosol exposure on tumor development and chronic toxicity is consistent with the significantly reduced levels of harmful and potentially harmful constituents in THS 2.2 aerosol relative to CS. The totality of the evidence from this study further supports the risk reduction potential of THS 2.2 for lung diseases in comparison with cigarettes.

K48-Linked Ubiquitination Contributes to Nicotine-Augmented Bone Marrow-Derived Dendritic-Cell-Mediated Adaptive Immunity

K48-linked ubiquitination determining antigen degradation and the endosomal recruitments of p97 and Sec61 plays vital roles in dendritic cell (DC) cross-presentation. Our previous studies revealed that nicotine treatment increases bone marrow-derived dendritic cell (BM-DC) cross-presentation and promotes BM-DC-based cytotoxic T lymphocyte (CTL) priming. But the effect of nicotine on K48-linked ubiquitination and the mechanism of nicotine-increased BM-DC cross-presentation are still uncertain. In this study, we first demonstrated that ex vivo nicotine administration obviously increased K48-linked ubiquitination in BM-DC. Then, we found that K48-linked ubiquitination was essential for nicotine-augmented cross-presentation, BM-DC-based CTL priming, and thereby the superior cytolytic capacity of DC-activated CTL. Importantly, K48-linked ubiquitination was verified to be necessary for nicotine-augmented endosomal recruitments of p97 and Sec61. Importantly, mannose receptor (MR), which is an important antigenic receptor for cross-presentation, was exactly catalyzed with K48-linked ubiquitination by the treatment with nicotine. Thus, these data suggested that K48-linked ubiquitination contributes to the superior adaptive immunity of nicotine-administrated BM-DC. Regulating K48-linked ubiquitination might have therapeutic potential for DC-mediated immune therapy.

PYR-41 and Thalidomide Impair Dendritic Cell Cross-Presentation by Inhibiting Myddosome Formation and Attenuating the Endosomal Recruitments of p97 and Sec61 via NF-κB Inactivation

PYR-41 and thalidomide have therapeutic effects on inflammation-associated diseases with side effects such as tumorigenesis. Cross-presentation allows dendritic cells (DC) to present endogenous antigen and induce protective immunity against microbe infection and tumors. But, up to now, the effects of PYR-41 and thalidomide on cross-presentation are still uncertain. In this study, we investigated the effect and mechanism of PYR-41 and thalidomide on DC cross-presentation by observing Myddosome formation, endosomal recruitment of p97 and Sec61, NF-κB activation, and cross-priming ability. We demonstrated that the inhibition of endosomal recruitment of p97 and Sec61, together with attenuated NF-κB activation and Myddosome formation, contributes to PYR-41- and thalidomide-impaired cross-presentation and thereby reverses cross-activation of T cells. These observations suggest that NF-κB signaling and p97 and Sec61 molecules are candidates for dealing with the side effects of PYR-41 and thalidomide.

Increased translocation of antigens to endosomes and TLR4 mediated endosomal recruitment of TAP contribute to nicotine augmented cross-presentation

Cross-presentation by dendritic cells (DCs) requires surface molecules such as lectin, CD40, langerin, heat shock protein, mannose receptor, mediated endocytosis, the endosomal translocation of internalized antigen, and the relocation of transporter associated with antigen processing (TAP). Although the activation of α7 nicotinic acetylcholine receptor (α7 nAchR) up-regulate surface molecule expression, augment endocytosis, and enhance cross-presentation, the molecular mechanism of α7 nAchR activation-increased cross-presentation is still poorly understood. In this study, we investigated the role of mannose receptor in nicotine-increased cross-presentation and the mechanism that endotoxins orchestrating the recruitment of TAP toward endosomes. We demonstrated that nicotine increase the expressiones of mannose receptor and Toll-like receptor 4 (TLR4) via PI3K-Akt-mTOR-p70S6 pathway. Both endosomal translocation of mannose receptor-internalized antigens and TLR4 sig- naling are necessary for nicotine-augmented cross-presentation and cross-priming. Importantly, the recruitment of TAP toward endosomes via TLR4-MyD88-IRAK4 signaling contributes to nicotine-increased cross-presentation and cross-activation of T cells. Thus, these data suggest that increased recruitment of TAP to Ag-containing vesicles contributes to the superior cross-presentation efficacy of α7 nAchR activated DCs.

Interleukin 6 trigged ataxia-telangiectasia mutated activation facilitates lung cancer metastasis via MMP-3/MMP-13 up-regulation

Our previous studies show that the phosphorylation of ataxia-telangiectasia mutated (ATM) induced by interleukin 6 (IL-6) treatment contributes to multidrug resistance formation in lung cancer cells, but the exact role of ATM activation in IL-6 increased metastasis is still elusive. In the present study, matrix metalloproteinase-3 (MMP-3) and MMP-13 were firstly demonstrated to be involved in IL-6 correlated cell migration. Secondly, IL-6 treatment not only increased MMP-3/MMP-13 expression but also augmented its activities. Thirdly, the inhibition of ATM phosphorylation efficiently abolished IL-6 up-regulating MMP-3/MMP-13 expression and increasing abilities of cell migration. Most importantly, the in vivo test showed that the inhibition of ATM abrogate the effect of IL-6 on lung cancer metastasis via MMP-3/MMP-13 down-regulation. Taken together, these findings demonstrate that IL-6 inducing ATM phosphorylation increases the expression of MMP-3/MMP-13, augments the abilities of cell migration, and promotes lung cancer metastasis, indicating that ATM is a potential target molecule to overcome IL-6 correlated lung cancer metastasis.

Ex vivo nicotine stimulation augments the efficacy of human peripheral blood mononuclear cell-derived dendritic cell vaccination via activating Akt-S6 pathway

Our previous studies showed that α7 nicotinic acetylcholine receptor (nAchR) agonist nicotine has stimulatory effects on murine bone marrow-derived semimature DCs, but the effect of nicotine on peripheral blood mononuclear cell- (PBMC-) derived human semimature dendritic cells (hu-imDCs) is still to be clarified. In the present study, hu-imDCs (cultured 4 days) were conferred with  ex vivo lower dose nicotine stimulation and the effect of nicotine on surface molecules expression, the ability of cross-presentation, DCs-mediated PBMC priming, and activated signaling pathways were determined. We could demonstrate that the treatment with nicotine resulted in increased surface molecules expression, enhanced hu-imDCs-mediated PBMC proliferation, upregulated release of IL-12 in the supernatant of cocultured DCs-PBMC, and augmented phosphorylation of Akt and ribosomal protein S6. Nicotine associated with traces of LPS efficiently enhanced endosomal translocation of internalized ovalbumin (OVA) and increased TAP-OVA colocalization. Importantly, the upregulation of nicotine-increased surface molecules upregulation was significantly abrogated by the inhibition of Akt kinase. These findings demonstrate that ex vivo nicotine stimulation augments hu-imDCs surface molecules expression via Akt-S6 pathway, combined with increased Ag-presentation result in augmented efficacy of DCs-mediated PBMC proliferation and Th1 polarization.

TIPE2 inhibits TNF-α-induced hepatocellular carcinoma cell metastasis via Erk1/2 downregulation and NF-κB activation

Tumor necrosis factor-α-induced protein 8-like 2 (TNFAIP8L2, TIPE2), which belongs to the TNF-α-induced protein 8 family, is a negative regulator of immune homeostasis. Although pro-inflammatory cytokines such as TNF-α have been reported to be involved in liver carcinoma metastasis, the effect of TIPE2 on hepatocellular carcinoma metastasis remains unknown. We demonstrate that TNF-α clearly augments MMP-13/MMP-3 expression and promotes cell migration in HepG2 cells through activation of the Erk1/2-NF-κB pathways. Interestingly, in addition to human PBLs, macrophages and fibroblasts, liver cancer cells specifically express TNF-α following LPS treatment. Most importantly, TIPE2 overexpression efficiently abrogates the effects of LPS on TNF-α secretion and abolishes the effects of TNF-α on MMP-13/MMP-3 upregulation, cell migration and Erk1/2-NF-κB activation. Taken together, these findings demonstrate that TIPE2 was able to suppress TNF-α-induced hepatocellular carcinoma metastasis by inhibiting Erk1/2 and NF-κB activation, indicating that both TNF-α and TIPE2 might be potential targets for the treatment of HCC metastasis.

Increased antigen presentation but impaired T cells priming after upregulation of interferon-beta induced by lipopolysaccharides is mediated by upregulation of B7H1 and GITRL

Dendritic cells are able to present Ag-derived peptides on MHC class I and II molecules and induce T cells priming. Lipopolysaccharides (LPS), an activator of Toll-like 4 receptor (TLR4) signaling, has been demonstrated to facilitate Ag-presentation, up-regulate surface molecules expression but impair T cells priming. In this study, we investigated the effect of LPS on nicotine-enhanced DCs-dependent T cells priming and the mechanisms of LPS orchestrating the immunosuppressive program. We could demonstrate that the treatment with LPS resulted in increased surface molecules expression, enhanced Ag-presentation, up-regulated release of TGF-beta, TNF-alpha, IL-6, and IFN-beta. Concomititantly, the upregulation of IFN-beta in DCs induces the up-regulation of coinhibitory molecules B7H1 and GITRL, which cause an impaired activation of naïve Ag-specific T cells and the induction of T cell tolerance by enhancing B7H1-PD-1 interactions and promoting GITRL-GITL facilitated Treg generation, respectively. These data provide a mechanistic basis for the immunomodulatory action of IFN-beta which might open new possibilities in the development of therapeutic approaches aimed at the control of excessive immune response and persistent infection.

Dendritic cell engineering for tumor immunotherapy: from biology to clinical translation

Dendritic cells (DCs) are the most potent APCs, with the ability to orchestrate a repertoire of immune responses. DCs play a pivotal role in the initiation, programming and regulation of tumor-specific immune responses, as they are poised to take up, process and present tumor antigens to naive or effector T lymphocytes. Although, to an extent, DC-based immunotherapeutic strategies have successfully induced specific anti-tumor responses in animal models, their clinical efficacy has rarely been translated into the clinic. This article attempts to present a complete picture of recent developments of DC-based therapeutic strategies addressing multiple components of tumor immunoenvironment. It also showcases certain practical intricacies in order to explore novel strategies for providing new impetus to DC-based cancer vaccination.

Nicotine up-regulated 4-1BBL expression by activating Mek-PI3K pathway augments the efficacy of bone marrow-derived dendritic cell vaccination

PURPOSE

To explore the role of 4-1BBL in nicotine-treated immature dendritic cells (imDCs) mediated anti-tumor effects.

METHODS

Bone marrow-derived imDCs were stimulated with nicotine and 4-1BBL expression was determinated by flow cytometry, Western blot and RT-PCR respectively. Then, the roles of 4-1BBL in nicotine-augmented DCs-dependent T cell proliferation, CTL priming and anti-tumor effects were investigated by BrdU cell proliferation assay, enzyme-linked immunospot assay and in vivo preventive effect on tumor development, respectively. Finally, using relative kinase inhibitors, the mechanism of 4-1BBL up-regulation by nicotine stimulation and the roles of Mek-PI3K signal pathways in nicotine-augmented DCs-dependent T cell proliferation were explored by Western blot and BrdU cell proliferation assay, respectively.

RESULTS

Firstly, nicotine could up-regulate 4-1BBL expression in both protein and mRNA levels. Secondly, the effects of nicotine-augmented DCs-dependent T-cell proliferation, CTL priming and anti-tumor effects could be significantly abolished by blocking CD80, CD86 and 4-1BBL activity, respectively. Thirdly, the combined blockages of CD80/CD86, CD80/4-1BBL, CD86/4-1BBL or CD80/CD86/4-1BBL signals could decrease 53.2 %, 29.6 %, 27.9 % and 54.5 % nicotine-enhanced T cell proliferation, respectively. Importantly, nicotine-induced 4-1BBL up-regulation could be decreased by the usage of Mek-PI3K pathway kinase inhibitors. The pre-treatment of Mek-p38-PI3K kinase inhibitors could obviously abolish nicotine-augmented DCs-dependent T cell proliferation.

CONCLUSIONS

CD80/CD86 and 4-1BBL are critical for nicotine augmented DCs-mediated anti-tumor effects. 4-1BBL and CD80/CD86 could be considered as potential candidates for preventive and therapeutic tumor vaccination.

TGF-β of lung cancer microenvironment upregulates B7H1 and GITRL expression in dendritic cells and is associated with regulatory T cell generation

The effects of TGF-β on dendritic cells (DCs) on the tumor microenvironment are not well understood. We report, here, the establishment of an in vitro lung cancer microenvironment by co-incubation of seminaphtharhodafluor (SNARF) labeled Lewis lung cancer (LLC) cells, carboxyfluorescein succinimidyl ester (CFSE) labeled fibroblasts and 4-chloromethyl-7-hydroxycoumarin (CMHC) labeled DCs. Raw 264.7, EL4 and NCI-H446 cells were able to synthesize TGF-β which was determined by flow cyto-metry and western blotting, respectively. Furthermore, TGF-β efficiently increased regulatory T-cell (Treg) expansion and upregulated DC B7H1 and GITRL expression. TGF-β and the co-incubation of LLC cells, fibroblasts with DCs could augment the expression of B7H1 and GITRL molecules of DCs. The data presented here indicate that the B7H1 and GITRL molecules may play an important role in TGF-β-induced Treg expansion of lung cancer microenvironment.

Nicotine stimulated bone marrow-derived dendritic cells could augment HBV specific CTL priming by activating PI3K-Akt pathway

Our previous studies have revealed that nicotine-treated immature dendritic cells (imDCs) have anti-tumor effects in murine lymphoma models. The present study is to explore HBV-specific CTL priming and its cytolytic activities of nicotine-treated murine DCs, the mechanism of α7 nicotinic acetylcholine receptor (nAChR) up-regulation by nicotine and the efficiency of nicotine with other cytokines. To address these hypotheses, bone marrow-derived imDCs were stimulated by nicotine and expression of α7 nAChR was firstly determined by flow cytometry and Western blot. Then, DCs-dependent HBV-specific T cell proliferation and IL-12 secretion were secondly determined by BrdU cell proliferation assay and ELISA, respectively. The HBV-specific CTL priming and its activities were further explored by intraperitoneal transfer of nicotine treated imDCs. The mechanism of nicotine up-regulating α7 nAChR was finally explored by Western blot. The results showed that: first, the maximal activation of PI3K and Akt was reached at 30 and 60-120 min respectively after nicotine stimulation. Nicotine up-regulated the expression of α7 nAChR by activating PI3K-Akt pathway in murine DCs; secondly, nicotine stimulation could enhance DCs' ability of HBV-specific T cell proliferation and IL-12 secretion; thirdly, adoptive transfer of nicotine stimulated DCs could induce HBV specific CTL priming in vivo and those CTL had cytolytic activities; fourthly, nicotine had equal efficiencies to 2 ng/ml IFN-γ in DCs-mediated T cell proliferation. All these data presented here indicated that nicotine treated imDCs might be considered as a potential candidate for HBV immunotherapy.

Lipopolysaccharide and dose of nicotine determine the effects of nicotine on murine bone marrow-derived dendritic cells

The reported effects of nicotine on dendritic cells (DCs) are controversial. To investigate the factors which determine the effects of nicotine on DCs, immature dendritic cells (imDCs) induced from murine bone marrow were treated with different doses of nicotine with or without lipopolysaccharides (LPS). The morphology and expression of the co-stimulatory molecules CD80, CD86, CD40 and CD54 were observed and determined by microscopy and flow cytometry, respectively. The results showed that, firstly, nicotine treatment promoted the development of DC precursors into imDCs with a semi-mature phenotype revealed by a higher expression of CD11c and more branched projections. Secondly, lower doses of nicotine (16.5 ng/ml), but not higher (200 μg/ml), up-regulated the expression of the co-stimulatory molecules CD80, CD40 and CD54 on imDCs. Co-administration of LPS and nicotine revealed differential effects on co-stimulatory molecule expression on imDCs. Thirdly and importantly, treatment with lower doses of nicotine (16.5 ng/ml) did not augment expression of the CD80, CD86, CD40 and CD54 molecules in mature DCs. Fourthly and interestingly, high doses of nicotine (more than 165 μg/ml) revealed pro-apoptotic activity but lower doses of nicotine (16.5–0.165 ng/ml) achieved an anti-apoptotic effect on imDCs. All data presented here indicate that the controversial effects of nicotine on DCs may be due to the LPS of the nicotinic environment and the dose of nicotine used.