Hongxin Deng

A novel injectable local hydrophobic drug delivery system: Biodegradable nanoparticles in thermo-sensitive hydrogel.

In this article, a novel local hydrophobic drug delivery system: nanoparticles in thermo-sensitive hydrogel, was demonstrated. First, honokiol, as a model hydrophobic drug, loaded poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone) (PCEC) nanoparticles were prepared by emulsion solvent evaporation method, and then were incorporated into thermo-sensitive F127 hydrous matrix. The obtained injectable hydrophobic drug delivery system can act as a depot for sustained release of honokiol in situ. The lower critical solution temperature (LCST) of the composite matrix increases with increase in the mass of incorporated nanoparticles, or with decrease in the amount of residual organic solvent in the system. Honokiol release profile in vitro was studied, and the results showed that honokiol could be sustained released from the system. The described injectable drug delivery system might have great potential application for local delivery of hydrophobic drugs such as honokiol.

IL-37 Ameliorates the Inflammatory Process in Psoriasis by Suppressing Proinflammatory Cytokine Production

IL-37 is a potent inhibitor of innate immunity by shifting the cytokine equilibrium away from excessive inflammation. Psoriasis is thought to be initiated by abnormal interactions between the cutaneous keratinocytes and systemic immune cells, triggering keratinocyte hyperproliferation. In the current study, we assessed IL-37 in two well-known psoriasis models: a human keratinocyte cell line (HaCaT) and the keratin 14 VEGF-A–transgenic mouse model. First, we used the HaCaT cell line, which was transiently transfected with an overexpressing IL-37 vector, and tested the effect of IL-37 on these cells using a mixture of five proinflammatory cytokines. IL-37 was effective in suppressing the production of CXCL8, IL-6, and S100A7, which were highly upregulated by the mixture of five proinflammatory cytokines. Keratin 14 VEGF-A–transgenic mice were treated with plasmid coding human IL-37 sequence–formulated cationic liposomes, and we observed potent immunosuppressive effects over the 18-d period. In this model, we observed reduced systemic IL-10 levels, local IFN-γ gene transcripts, as well as mild mast cell infiltration into the psoriatic lesions of the mice. Immunohistochemical analysis indicated that IL-37 was expressed by effector memory T cells, as well as macrophages, in human psoriatic plaques. In conclusion, our studies strongly indicate that IL-37 plays a potent immunosuppressive role in the pathogenesis of both experimental psoriasis models in vitro and in vivo by downregulating proinflammatory cytokines. Importantly, our findings highlight new therapeutic strategies that can be designed to use this immunosuppressive anti-inflammatory cytokine in psoriasis and other inflammatory cutaneous diseases.

A gene therapy for cancer based on the angiogenesis inhibitor, vasostatin

The growth and persistence of solid tumors and their metastasis are angiogenesis-dependent. Vasostatin, the N-terminal domain of calreticulin inclusive of amino acids 1–180, is a potent angiogenesis inhibitor. To investigate whether intramuscular administration of vasostatin gene has the antitumor activity in mouse tumor models, we constructed a plasmid DNA encoding vasostatin and a control vector. Production and secretion of vasostatin protein by COS cells transfected with the plasmid DNA encoding vasostatin (pSecTag2B-vaso) were confirmed by Western blot analysis and ELISA. Conditioned medium from vasostatin-transfected COS cells apparently inhibited human umbilical vein endothelial cell (HUVEC) and mouse endothelial cell (SVEC4-10) proliferation, compared with conditioned medium from the COS cells transfected with control vector or non-transfected cells. Treatment with pSecTag2B-vaso twice weekly for 4 weeks resulted in the inhibition of tumor growth and the prolongation of the survival of tumor-bearing mice. The sustained high level of vasostatin protein in serum could be identified in ELISA. Angiogenesis was apparently inhibited in tumor by immunohistochemical analysis. Angiogenesis was also inhibited in the chicken embryo CAM assay and mouse corneal micropocket assay. The increased apoptotic cells were found within the tumor tissues from the mice treated with plasmid DNA encoding vasostatin. Taken together, the data in the present study indicate that the cancer gene therapy by the intramuscular delivery of plasmid DNA encoding vasostatin, is effective in the inhibition of the systemic angiogenesis and tumor growth in murine models. The present findings also provide further evidence of the anti-tumor effects of the vasostatin, and may be of importance for the further exploration of the application of this molecule in the treatment of cancer.

SKLB1002, a Novel Potent Inhibitor of VEGF Receptor 2 Signaling, Inhibits Angiogenesis and Tumor Growth In Vivo

Purpose: VEGF receptor 2 (VEGFR2) inhibitors, as efficient antiangiogenesis agents, have been applied in the cancer treatment. However, currently most of these anticancer drugs suffer some adverse effects. Discovery of novel VEGFR2 inhibitors as anticancer drug candidates is still needed. Experimental Design: In this investigation, we adopted a restricted de novo design method to design VEGFR2 inhibitors. We selected the most potent compound SKLB1002 and analyzed its inhibitory effects on human umbilical vein endothelial cells (HUVEC) in vitro. Tumor xenografts in zebrafish and athymic mice were used to examine the in vivo activity of SKLB1002. Results: The use of the restricted de novo design method indeed led to a new potent VEGFR2 inhibitor, SKLB1002, which could significantly inhibit HUVEC proliferation, migration, invasion, and tube formation. Western blot analysis was conducted, which indicated that SKLB1002 inhibited VEGF-induced phosphorylation of VEGFR2 kinase and the downstream protein kinases including extracellular signal-regulated kinase, focal adhesion kinase, and Src. In vivo zebrafish model experiments showed that SKLB1002 remarkably blocked the formation of intersegmental vessels in zebrafish embryos. It was further found to inhibit a new microvasculature in zebrafish embryos induced by inoculated tumor cells. Finally, compared with the solvent control, administration of 100 mg/kg/d SKLB1002 reached more than 60% inhibition against human tumor xenografts in athymic mice. The antiangiogenic effect was indicated by CD31 immunohistochemical staining and alginate-encapsulated tumor cell assay. Conclusions: Our findings suggest that SKLB1002 inhibits angiogenesis and may be a potential drug candidate in anticancer therapy. Clin Cancer Res; 17(13); 4439–50. ©2011 AACR.

Immunogene Therapy of Tumors with Vaccine Based on Xenogeneic Epidermal Growth Factor Receptor

The breaking of immune tolerance against self epidermal growth factor receptor (EGFr) should be a useful approach for the treatment of receptor-positive tumors with active immunization. To test this concept, we constructed a plasmid DNA encoding extracellular domain of xenogeneic (human) EGFr (hEe-p) or corresponding control mouse EGFr (mEe-p) and empty vector (c-p). Mice immunized with hEe-p showed both protective and therapeutic antitumor activity against EGFr-positive tumor. Sera isolated from the hEe-p-immunized mice exhibited positive staining for EGFr-positive tumor cells in flow cytometric analysis and recognized a single 170-kDa band in Western blot analysis. Ig subclasses responded to rEGFr proteins were elevated in IgG1, Ig2a, and Ig2b. There was the deposition of IgG on the tumor cells. Adoptive transfer of the purified Igs showed the antitumor activity. The increased killing activity of CTL against EGFr-positive tumor cells could be blocked by anti-CD8 or anti-MHC class I mAb. In vivo depletion of CD4+ T lymphocytes could completely abrogate the antitumor activity, whereas the depletion of CD8+ cells showed partial abrogation. The adoptive transfer of CD4-depleted (CD8+) or CD8-depleted (CD4+) T lymphocytes isolated from mice immunized with hEe-p vaccine showed the antitumor activity. In addition, the increase in level of both IFN-γ and IL-4 was found. Taken together, these findings may provide a new vaccine strategy for the treatment of EGFr-positive tumors through the induction of the autoimmune response against EGFr in a cross-reaction between the xenogeneic homologous and self EGFr.

Human α-defensin-1 inhibits growth of human lung adenocarcinoma xenograft in nude mice

Human α-defensin-1 (HNP1), a small antimicrobial peptide, shows cytotoxicity to tumor cells in vitro and inhibitory activity for pathologic neovascularization in vivo. Here, we did a gene therapy with a plasmid that expresses a secretable form of HNP1 for assaying its antitumor activity. The expression and secretion of HNP1 were determined by reverse transcription-PCR and ELISA in vitro. We found that expression of HNP1 in A549 tumor cells caused significant growth inhibition. This effect is most likely cell autonomous, as a significant amount of recombinant HNP1 protein was found to be accumulated in the cytoplasm by immunohistochemical staining using an anti-HNP1 antibody and the supernatant containing secreted HNP1 failed to produce any noticeable antitumor activity. Flow cytometry and Hoechst 33258 staining showed that the number of apoptotic cells among the A549 cells expressing recombinant HNP1 proteins was significantly greater than that of the nontransfected control cultures, suggesting that this growth-inhibitory activity was due to an apoptotic mechanism triggered by the intracellular HNP1. The antitumor activity of intracellularly expressed HNP1 was also shown in vivo. Decreased microvessel density and increased lymphocyte infiltration were observed in tumor tissue from HNP1-treated mice through histologic analysis. These results indicate that intracellularly expressed HNP1 induces tumor cell apoptosis, which inhibits tumor growth. The antiangiogenesis effect of HNP1 may contribute to its inhibitory activity in vivo, and HNP1 might involve the host immune response to tumor. These findings provide a rationale for developing HNP1-based gene therapy for cancer. [Mol Cancer Ther 2008;7(6):1588–97]

Active immunotherapy of tumors with a recombinant xenogeneic endoglin as a model antigen

Angiogenesis play a critical role in tumor growth and metastasis. Increasing evidence suggests that endoglin is a powerful marker of angiogenesis in solid malignancies. Thus, breaking of immune tolerance of self‐endoglin‐associated angiogenesis is an attractive approach to cancer therapy. To test this concept, we recombined the extracellular domains of porcine endoglin, and used it as a xenogeneic vaccine. We found that immunotherapy with porcine endoglin was effective at both protective and therapeutic anti‐tumor immunity in several mouse tumor models. Autoantibodies against mouseendoglin were identified by Western blot and ELISA. IgG1 and IgG2b were substantially increased. Anti‐endoglin antibody‐producing B cells were detectable by ELISPOT assay. There was endothelial deposition of immunoglobulins within tumors. The anti‐tumor activity was also induced by the adoptive transfer of the purified immunoglobulins. Angiogenesis was apparently inhibited within the tumor tissues and on the alginate beads. The increased apoptotic cells were found within the tumor tissues from the mice treated with porcine endoglin. The anti‐tumor activity and production of autoantibodies againstmouse endoglin could be abrogated by depletion of CD4+ T lymphocytes. Remarkably, no marked toxicity was found in the immunized mice. These observations may provide an alternative rationalstrategy for active cancer immunotherapy.

Combination of low‐dose cisplatin and recombinant xenogeneic endoglin as a vaccine induces synergistic antitumor activities

Angiogenesis is critical to the growth and metastasis of solid tumors, and acquired drug resistance is one of the major hindrances to chemotherapy. Thus, we sought a rational strategy using the combination of antiangiogenic biotherapy and chemotherapy for cancer therapy. We explored the efficacy of a strategy combining low‐dose cisplatin and a recombinant xenogeneic endoglin as a protein vaccine, which we previously demonstrated to have effective antiangiogenic effects in several mouse models. We found that both low‐dosage cisplatin and xenogeneic endoglin vaccine individually resulted in effective suppression of tumor growth in 2 tumor models via inhibition of tumor angiogenesis. Remarkably, the combination therapy resulted in not only significant antiangiogenic effects but also additional promotion of tumor cell apoptosis and inhibition of tumor cell proliferation, without any ensuing increase in host toxicity during the course of treatment, which lasted for 6 months. In addition, the combination demonstrated a synergistic relationship, which was shown in all of the synergistic indexes, i.e., tumor volume, angiogenesis, apoptosis and proliferation. Both antibodies and antibody‐producing B cells against mouse self‐endoglin were observed in all mice immunized by the xenogeneic endoglin vaccine (alone and combination), which suggested that low‐dose cisplatin did not suppress the host immune response but potentiated the antitumor activity of the xenogeneic endoglin vaccine. These observations may provide the basis for an effective alternative strategy for cancer therapy in the near future.

Induction of apoptosis and tumor regression by vesicular stomatitis virus in the presence of gemcitabine in lung cancer

Vesicular stomatitis virus (VSV) has been shown to replicate rapidly in vitro and kill selectively a variety of tumor cell lines. The present study was designed to determine whether gemcitabine potentiates the antitumor activity of VSV in vitro and in vivo. A549 human lung adenocarcinoma cells and LLC Lewis lung carcinoma cells were treated with VSV (0.1–10 plaque‐forming units per cell) plus gemcitabine (20 nM to 20 μM). Mice bearing A549 or LLC were treated with VSV (5 × 104 to 1 × 108 plaque‐forming units) daily for 5 days plus gemcitabine (5–125 mg/kg/day) once every 3 days for 4 times. Induction of apoptosis and effects on growth inhibition were assessed. The lung cancer cells treated with VSV plus gemcitabine displayed the apparently increased apoptotic cells compared with treatment with VSV or gemcitabine alone. The combined treatment with VSV plus gemcitabine induced the apparent antitumor activity with complete regression of the established lung cancer in both A549 and LLC lung cancer models and augmented the induction of apoptosis in lung cancer cells in vivo as well. This study suggests that the combined treatment with VSV plus gemcitabine may augment the induction of apoptosis in lung cancer cells in vitro and in vivo, and that the augmented antitumor activity in vivo may result from the increased induction of apoptosis in lung cancer cells. The present findings may be of importance to the further exploration of the potential application of this combined approach in the treatment of lung cancer.

Therapeutic upregulation of Class A scavenger receptor member 5 inhibits tumor growth and metastasis

Class A scavenger receptor member 5 (SCARA5) is a new member of the Class A scavenger receptors that has been proposed recently as a novel candidate tumor suppressor gene in human hepatocellular carcinoma. In the present study, we found that SCARA5 expression was frequently downregulated in various cancer cell lines and tumor samples. In addition, upregulation of SCARA5 expression in human cancer cell line (U251) led to a significant decrease in cell proliferation, clone formation, migration, and invasion in vitro. Furthermore, systemic treatment of tumor‐bearing mice with SCARA5–cationic liposome complex not only reduced the growth of subcutaneous human glioma tumors, but also markedly suppressed the spontaneous formation of lung metastases. Similar results were obtained in another experiment using mice bearing experimental A549 lung metastases. Compared with the untreated control group, mice treated with SCARA5 exhibited reductions in both spontaneous U251 and experimental A549 lung metastases rates of 77.3% and 70.2%, respectively. Western blot analysis was used to explore the molecular mechanisms involved and revealed that SCARA5 physically associated with focal adhesion kinase. Interestingly, upregulation of SCARA5 inactivated signal transducer and activator of transcription 3, as well as downstream signaling including cyclinB1, cyclinD1, AKT, survivin, matrix metalloproteinase‐9 and vascular endothelial growth factor‐A. Overall, the findings of the present study provide the first evidence that SCARA5 might be a promising target for the development of new antimetastatic agents for the gene therapy of cancer.