Ting Niu

Immunogene therapy of tumors with vaccine based on Xenopus homologous vascular endothelial growth factor as a model antigen

Overcoming immune tolerance of the growth factors associated with tumor growth should be a useful approach to cancer therapy by active immunity. We used vascular endothelial growth factor (VEGF) as a model antigen to explore the feasibility of the immunogene tumor therapy with a vaccine based on a single xenogeneic homologous gene, targeting the growth factors associated with angiogenesis. To test this concept, we constructed a plasmid DNA encoding Xenopus homologous VEGF (XVEGF-p) and control vectors. We found that immunogene tumor therapy with a vaccine based on XVEGF was effective at both protective and therapeutic antitumor immunity in several tumor models in mice. VEGF-specific autoantibodies in sera of mice immunized with XVEGF-p could be found in Western blotting analysis and ELISA assay. The purified immunoglobulins were effective at the inhibition of VEGF-mediated endothelial cell proliferation in vitro, and at antitumor activity and the inhibition of angiogenesis by adoptive transfer in vivo. The elevation of VEGF in the sera of the tumor-bearing mice could be abrogated with XVEGF-p immunization. The antitumor activity and production of VEGF-specific autoantibodies, significantly elevated IgG1 and IgG2b, could be abrogated by the depletion of CD4+ T lymphocytes. The observations may provide a vaccine strategy for cancer therapy through the induction of autoimmunity against the growth factors associated with tumor growth in a cross reaction with single xenogeneic homologous gene and may be of importance in the further exploration of the applications of other xenogeneic homologous genes identified in human and other animal genome sequence projects in cancer therapy.

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.

Synergistic anti-tumor effect of recombinant human endostatin adenovirus combined with gemcitabine.

Endostatin is an important endogenous inhibitor of neovascularization, which has been widely used in anti-angiogenesis therapy for cancer. To fully explore the potential of endostatin, we evaluated the anti-tumor efficacy of the combination of recombinant human endostatin adenovirus and low-dose gemcitabine in nude mice. We injected recombinant human endostatin adenovirus intratumorally plus a low dose of gemcitabine i.p. routinely. The combination treatment produced no side-effects, and resulted in marked suppression in tumor formation and growth of established human lung carcinoma xenografts in nude mice, with decreased microvessel density and increased apoptosis percentage. Our data support the idea of synergistic anti-tumor properties of endostatin plus low-dose chemotherapy against human lung cancer in vivo.

Active antitumor immunity elicited by vaccine based on recombinant form of epidermal growth factor receptor

Active immunotherapy targeting epidermal growth factor receptor (EGFR) should be another attractive approach to the treatment of EGFR-positive tumors. To test this concept, the authors evaluated the potential immune responses and antitumor activities elicited by dendritic cells pulsed with recombinant ectodomain of mouse EGFR (DC-edMER). Spleen cells isolated from DC-edMER-vaccinated mice showed a high quantity of EGFR-specific antibody-producing cells. EGFR-reactive antibody in sera isolated from vaccinated mice was identified and shown to be effective against tumors in vitro and in vivo by adoptive transfer. DC-edMER vaccine also elicited cytotoxic T-lymphocyte responses that could mediate antitumor effects in vitro and adoptive transfer in vivo. In addition, EGFR-specific cytokines responses were elicited by DC-edMER vaccine. Immunization with DC-edMER resulted in tumor regression and prolonged survival in mice challenged with Lewis lung carcinomas and mammary cancer models. Depletion of CD4+ T lymphocytes could completely abrogate the antitumor activity and EGFR-specific antibody responses, whereas the depletion of CD8+ T lymphocytes showed partial abrogation of the antitumor activity but antibody was still detected. Furthermore, tumor-induced angiogenesis was suppressed in DC-edMER-vaccinated mice or mice treated with antibody adoptive transfer. Taken together, these findings suggest the antitumor immunity could be induced by DC-edMER, which may involve both humoral and cellular immunity, and may provide insight into the treatment of EGFR-positive tumors through the induction of active immunity against EGFR.

Discovery of Selective Histone Deacetylase 6 Inhibitors Using the Quinazoline as the Cap for the Treatment of Cancer.

Novel selective histone deacetylase 6 (HDAC6) inhibitors using the quinazoline as the cap were designed, synthesized, and evaluated for HDAC enzymatic assays. N-Hydroxy-4-(2-methoxy-5-(methyl(2-methylquinazolin-4-yl)amino)phenoxy)butanamide, 23bb, was the most potent selective inhibitor for HDAC6 with an IC50 of 17 nM and showed 25-fold and 200-fold selectivity relative to HDAC1 and HDAC8, respectively. In vitro, 23bb presented low nanomolar antiproliferative effects against panel of cancer cell lines. Western blot analysis further confirmed that 23bb increased acetylation level of α-tubulin in vitro. 23bb has a good pharmacokinetic profile with oral bioavailability of 47.0% in rats. In in vivo efficacy evaluations of colorectal HCT116, acute myelocytic leukemia MV4-11, and B cell lymphoma Romas xenografts, 23bb more effectively inhibited the tumor growth than SAHA even at a 4-fold reduced dose or ACY-1215 at the same dose. Our results indicated that 23bb is a potent oral anticancer candidate for selective HDAC6 inhibitor and deserves further investigation.

Suppression of lung cancer in murine model: treated by combination of recombinant human endostsatin adenovirus with low-dose cisplatin

BackgroundThe sustained growth of tumors necessitates neovascularization. As one of the potent endogenous vascular inhibitors, endostatin has been widely used in antiangiogenesis therapy for tumor. Cisplatin is normally administered in chemotherapy for lung cancer but accompanied with serious side effects. In the current study, we investigated a novel chemo-antiangiogenesis therapeutic strategy to both improve toxic effects on lung cancer cells and reduce damages to normal cells in the anti-tumor therapy.MethodsIn vitro, we transduced LLC cells with Ad-hEndo and collected supernatants. Western blotting analysis of the supernatants revealed expression of endostatin. In vivo, to fully investigate the suppression effect on murine lung cancer of the combination therapy, we injected recombinant human endostatin adenovirus intratumorally plus a low dose of cisplatin intraperitoneally routinely. The tumor volume and survival time were observed. Angiogenesis was apparently inhibited within the tumor tissues and on the alginate beads. Assessment of apoptotic cells by the TUNEL assay was conducted in the tumor tissues.ResultsThe combination treatment significantly suppressed the tumor growth and prolonged survival time of the murine LLC tumor model. This anti-tumor activity was associated with decreased microvessel density and increased apoptotic index of tumor cells.ConclusionAccording to the results in this study, recombinant human endostatin adenovirus in combination with a low dose of cisplatin demonstrated apparent synergistic anti-tumor activity without marked toxicity. Thus, these observations may provide a rational alternative for lung cancer treatment.

Potential role of exosome-associated microRNA panels and in vivo environment to predict drug resistance for patients with multiple myeloma

Multiple myeloma (MM) is the second most common hematologic neoplasms and an appropriate in vivo environment for myeloma cells has potential implications for initiation, progression, and metastasis of MM. Exosomes, entities carrying microRNAs (miRNAs) to target locations, participate in the cross-talk between myeloma cells and nonmalignant components of the in vivo environment. This study disclosed the emerging roles of circulating exosome-associated miRNAs in drug resistance (DR) of MM. To this end, the medical records of consecutively hospitalized MM patients, who received novel agents-based therapies, were analyzed. Then, an optimized procedure was established for exosome isolation and exosomal RNA analysis. The exosome-associated miRNA expression patterns for predicting bortezomib (Bz) resistance of MM were further examined using a microarray. In total, 204 patients were enrolled with DR rates of 36.5%, 73.1% and 81.8% in the bortezomib (Bz), thalidomide and lenalidomide containing groups. The serum total light chain ratio ≥ 100, CRP ≥ 20 mg/L, and the second-line usage increased risks of acquired Bz-resistance. Among 68 cases having genetic tests, a high risk factor for predicting de novo DR was 1q21 amplification, which also correlated with lower levels of cholesterol and LDL-C. Moreover, nano-sized exosomes were isolated with significantly increasing internal RNAs and down-regulation of exosomal miR-16-5p, miR-15a-5p and miR-20a-5p, miR-17-5p was revealed in the patients resistant to Bz. The routine workup of MM hardly suggested a value for DR prediction. The circulating exosomes carrying miRNAs provided a window that permits a better understanding of the in vivo intercellular crosstalk in MM patients.

Effective induction therapy with subcutaneous administration of bortezomib for newly diagnosed POEMS syndrome: a case report and a review of the literature.

POEMS syndrome is characterized by polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skin changes. Bortezomib is an important component of the chemotherapy regimen associated with multiple myeloma, and has been previously applied to POEMS syndrome. We present a 56-year-old Chinese man who was given subcutaneous administration of bortezomib as part of the BDex (bortezomib–dexamethasone) regimen for his POEMS syndrome. The peripheral neuropathy and laboratory-test results of the patient improved dramatically with 4 cycles of treatment, resulting in a complete response. In addition, the treatment was well tolerated and adequate peripheral blood hematopoietic stem cells were collected for an ensuing autologous stem cell transplant.

Antitumour immunity mediated by mannan-modified adenovirus vectors expressing VE-cadherin

Anti-angiogenesis represents an indispensible strategy for cancer therapy. As a strictly endothelial-specific adhesion molecule, vascular endothelial cadherin (VE-cadherin, VE-cad) is a promising anti-angiogenesis target. In this study a recombinant adenovirus vector modified with mannan was used to deliver VE-cad (AdVEC-m) and we tried to explore its feasibility as an antitumour agent in mouse cancer models. The immunogenic delivery of VE-cad resulted in obvious prophylactic and therapeutic inhibition of tumour growth and prolonged survival in mice. In the meantime angiogenesis declined apparently within the tumours measured by immunohistochemistry staining and coated alginate bead assay in vivo. Anti-VE-cad antibodies were identified by western blot analysis and enzyme-linked immunosorbent assay (ELISA). VE-cad-specific T lymphocyte cytotoxicity responses (CTL) were detected by chromium (51Cr) release assay of splenocytes from AdVEC-m treated mice. These results demonstrate that mannan modification is able to enhance antigen delivery and immune responses, and the way of immunogenic delivery (AdVEC-m) is expected to provide an attractive vaccine strategy for cancer immunotherapy.

SKLB-677, an FLT3 and Wnt/β-catenin signaling inhibitor, displays potent activity in models of FLT3-driven AML

FLT3 has been identified as a valid target for the treatment of acute myeloid leukemia (AML), and some FLT3 inhibitors have shown very good efficacy in treating AML in clinical trials. Nevertheless, recent studies indicated that relapse and drug resistance are still difficult to avoid, and leukemia stem cells (LSCs) are considered one of the most important contributors. Here, we report the characterization of SKLB-677, a new FLT3 inhibitor developed by us recently. SKLB-677 exhibits low nanomolar potency in biochemical and cellular assays. It is efficacious in animal models at doses as low as 1mg/kg when administrated orally once daily. In particular, SKLB-677 but not first-generation and second-generation FLT3 inhibitors in clinical trials has the ability to inhibit Wnt/β-catenin signaling; Wnt/β-catenin signaling is required for the development of LSCs, but not necessary for the development of adult hematopoietic stem cells (HSCs). This compound indeed showed considerable suppression effects on leukemia stem-like cells in in vitro functional assays, but had no influence on normal HSCs. Collectively, SKLB-677 is an interesting lead compound for the treatment of AML, and deserves further investigations.