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

Immunotherapy combining tumor and endothelium cell lysis with immune enforcement by recombinant MIP-3α Newcastle disease virus in a vessel-targeting liposome enhances antitumor immunity

Background

Several agents for oncolytic immunotherapy have been approved for clinical use, but monotherapy is modest for most oncolytic agents. The combination of several therapeutic strategies through recombinant and nanotechnology to engineer multifunctional oncolytic viruses for oncolytic immunotherapy is a promising strategy.

Methods

An endothelium-targeting iRGD-liposome encapsulating a recombinant Newcastle disease virus (NDV), which expresses the dendritic cell (DC) chemokine MIP-3α (iNDV3α-LP), and three control liposomes were constructed. MIP-3α, HMGB1, IgG, and ATP were detected by western blotting or ELISA. The chemotaxis of DCs was examined by Transwell chambers. The phenotypes of the immune cells were analyzed by flow cytometry. The antitumor efficiency was investigated in B16 and 4T1 tumor-bearing mice. Immunofluorescence and immunohistochemistry were used to observe the localization of liposomes, molecular expression and angiogenesis. Synergistic index was calculated using the data of tumor volume, tumor angiogenesis and tumor-infiltrating lymphocytes.

Results

Compared with NDV-LP, treatment with iNDV3α-LP and NDV3α-LP induced stronger virus replication and cell lysis in B16 and 4T1 tumor cells and human umbilical vein endothelial cells (HUVECs) with the best response observed following iNDV3α-LP treatment. B16 and 4T1 cells treated with iNDV3α-LP produced more damage-associated molecular pattern molecules, including secreted HMGB1, ATP, and calreticulin. Moreover, iNDV3α-LP specifically bound to αvβ3-expressing 4T1 cells and HUVECs and to tumor neovasculature. Tumor growth was significantly suppressed, and survival was longer in iNDV3α-LP-treated B16-bearing and 4T1-bearing mice. A mechanism study showed that iNDV3α-LP treatment initiated the strongest tumor-specific cellular and humoral immune response. Moreover, iNDV3α-LP treatment could significantly suppress tumor angiogenesis and reverse the tumor immune suppressive microenvironment in both B16-bearing and 4T1-bearing mice.

Conclusions

In this study, iNDV3α-LP had several functions, such as tumor and vessel lysis, MIP-3α immunotherapy, and binding to αvβ3-expressing tumor and its neovasculature. iNDV3α-LP treatment significantly suppressed tumor angiogenesis and reversed the tumor immunosuppressive microenvironment. These findings offer a strong rationale for further clinical investigation into a combination strategy for oncolytic immunotherapy, such as the formulation iNDV3α-LP in this study.

Engineered porous/hollow Burkholderia pseudomallei loading tumor lysate as a vaccine

Due to its size, shape, and inherent expression of pathogen-associated molecular patterns and invasion-assistant adhesion proteins, Burkholderia pseudomallei can easily attach to, and then be internalized by, dendritic cells (DCs), leading to more efficient antigen cross-presentation if modified as carrier. Herein, we engineered Burkholderia pseudomallei as a porous/hollow carrier (SB) for loading tumor lysates (L) and adjuvant CpG (C) to be used as a tumor vaccine (SB-LC). We found that the adhesion proteins of Burkholderia pseudomallei promote internalization of the SB-LC vaccine by DCs, and result in enhanced DC maturation and antigen cross-presentation. SB-LC induces robust cellular and humoral antitumor responses that synergistically inhibit tumor growth with minimal adverse side effects in several tumor models. Moreover, SB-LC vaccination reverses the immunosuppressive tumor microenvironment, apparently as a result of CD8⁺-induced tumor ferroptosis. Thus, SB-LC is a potential model tumor vaccine for translating into a clinically viable treatment option.

Therapeutic Vaccines for Cancer Immunotherapy

The rapid development of nanobiotechnology has enabled progress in therapeutic cancer vaccines. These vaccines stimulate the host innate immune response by tumor antigens followed by a cascading adaptive response against cancer. However, an improved antitumor immune response is still in high demand because of the unsatisfactory clinical performance of the vaccine in tumor inhibition and regression. To date, a complicated tumor immunosuppressive environment and suboptimal design are the main obstacles for therapeutic cancer vaccines. The optimization of tumor antigens, vaccine delivery pathways, and proper adjuvants for innate immune response initiation, along with reprogramming of the tumor immunosuppressive environment, is essential for therapeutic cancer vaccines in triggering an adequate antitumor immune response. In this review, we aim to review the challenges in and strategies for enhancing the efficacy of therapeutic vaccines. We start with the summary of the available tumor antigens and their properties and then the optimal strategies for vaccine delivery. Subsequently, the vaccine adjuvants focused on the intrinsic adjuvant properties of nanostructures are further discussed. Finally, we summarize the combination strategies with therapeutic cancer vaccines and discuss their positive impact in cancer immunity.

CD105 Over-expression Is Associated with Higher WHO Grades for Gliomas

CD105 is an ancillary receptor of transforming growth factor beta (TGF-β), which has been suggested as a suitable biomarker for cancer-related angiogenesis and neovascularization (Nassiri et al. in Anticancer Res 31:2283-2290, 2011). However, the clinical significance of CD105 in WHO grade was rarely reported and the effects of CD105 signal transduction pathway on gliomas remain controversial and unclear. To get a convincing conclusion, performing a meta-analysis is essential. Relevant literature studies were included via careful evaluation, and standard mean difference (SMD) and hazard ratio (HR) with 95 % confidence intervals (95 % CIs) was calculated. We also made funnel plots to test the heterogeneity. In the present meta-analysis, a total of 11 eligible literatures involving 796 patients were incorporated. They were all conducted in China, revealing that CD105 overexpression in glioma tissues was strongly linked to high WHO grading (III+IV) (SMD -1.785, 95 % CI -2.133, -1.437; p = 0.000). No significant associations between CD105 and age (SMD -0.505, 95 % CI -1.054, 0.043; p = 0. 071), CD105 and gender (SMD 0.101, 95 % CI -0.103, 0.305; p = 0.333), and CD105 and tumor size (SMD -0.433, 95 % CI -1.326, 0.459; p = 0. 341) were detected. Besides, CD105 expression was closely associated with glioma patients' 3-year overall survival (OS; n = 2; HR = 4.357, 95 % CI 1.412, 7.303; p = 0.004). On the basis of Begg's and Egger's test or funnel plot, no publication bias was detected. In a nutshell, this meta-analysis demonstrated that CD105 overexpression correlates to higher WHO grade and poor survival and could be indicated as a helpful prognostic and diagnostic marker, or a useful therapy target.

Cancer prevention and therapy through the modulation of the tumor microenvironment

Cancer arises in the context of an in vivo tumor microenvironment. This microenvironment is both a cause and consequence of tumorigenesis. Tumor and host cells co-evolve dynamically through indirect and direct cellular interactions, eliciting multiscale effects on many biological programs, including cellular proliferation, growth, and metabolism, as well as angiogenesis and hypoxia and innate and adaptive immunity. Here we highlight specific biological processes that could be exploited as targets for the prevention and therapy of cancer. Specifically, we describe how inhibition of targets such as cholesterol synthesis and metabolites, reactive oxygen species and hypoxia, macrophage activation and conversion, indoleamine 2,3-dioxygenase regulation of dendritic cells, vascular endothelial growth factor regulation of angiogenesis, fibrosis inhibition, endoglin, and Janus kinase signaling emerge as examples of important potential nexuses in the regulation of tumorigenesis and the tumor microenvironment that can be targeted. We have also identified therapeutic agents as approaches, in particular natural products such as berberine, resveratrol, onionin A, epigallocatechin gallate, genistein, curcumin, naringenin, desoxyrhapontigenin, piperine, and zerumbone, that may warrant further investigation to target the tumor microenvironment for the treatment and/or prevention of cancer.

Vaccination approach to anti-angiogenic treatment of cancer

Improvement of patient survival by anti-angiogenic therapy has proven limited. A vaccination approach inducing an immune response against the tumor vasculature combines the benefits of immunotherapy and anti-angiogenesis, and may overcome the limitations of current anti-angiogenic drugs. Strategies to use whole endothelial cell vaccines and DNA- or protein vaccines against key players in the VEGF signaling axis, as well as specific markers of tumor endothelial cells, have been tested in preclinical studies. Current clinical trials are now testing the promise of this specific anti-cancer vaccination approach. This review will highlight the state-of-the-art in this exciting field of cancer research.

Bacterial surface display of endoglin by antigen 43 induces antitumor effectiveness via bypassing immunotolerance and inhibition of angiogenesis

Various angiogenesis-related self-molecules have been considered to be therapeutic targets. However, the direct use of self-molecules as vaccines is not recommended because of the inherent ability of the host to develop immune tolerance. Antigen 43 (Ag43) is a surface protein found in E. coli and contains an α and a β subunits, which contains multiple T epitopes in α subunit. Here we construct a novel Ag43 surface display system (Ag43 system) to express Ag43 chimeric proteins to disrupt immune tolerance against self-molecules. The Ag43 system was constructed from an Escherichia coli strain Tan109, derived from JM109, in which the Ag43 gene was deleted and a recombinant plasmid (pETAg43') expressing a partial Ag43 gene was introduced. The extracellular domain of angiogenesis-related endoglin gene was then subcloned into plasmid pETAg43', resulting in a recombinant plasmid pETAg43'/END(e) which was then used to transform Tan109 for protein expression. We found that Ag43 and endoglin chimeric protein (Ag43'/END(e) ) was expressed on the bacterial surface. The chimeric protein could be separated from the bacterial surface by heating to 60°C and yet retain activity. We used Ag43'/END(e) as a protein vaccine and found that it could disrupt immune tolerance against endoglin by inducing significant antitumor activities and inhibit angiogenesis in several tumor models without significant side effects. These data suggest that Ag43'/END(e) chimeric protein is a potential model vaccine for active tumor immunotherapy, and that Ag43 system could be an effective tool for novel vaccine preparation to break immune tolerance to other angiogenesis-related self-molecules for cancer therapy.

Cytochalasin D promotes pulmonary metastasis of B16 melanoma through expression of tissue factor

Cytochalasin D (CytD) targets actin, a ubiquitous protein in eukaryotic cells. Previous studies have focused mainly on the antitumor effects of CytD. We previously found CytD to promote lung metastasis in B16 melanoma cells, which we had not anticipated, and, therefore, in the present study we investigated the possible underlying mechanisms. B16 melanoma cells were co-cultured with CytD and other agents and used to establish a lung metastatic model. In this B16 melanoma metastatic model, significantly increased lung metastasis and lung weight were found in CytD-treated mice, which was almost completely suppressed by tissue factor (TF) RNA interference expressed via lentivirus. The results of northern and western blot, and real-time RT-PCR analysis showed that the expression of TF was significantly upregulated in B16 cells treated with CytD but was significantly inhibited by TF RNA interference. In addition, upregulation and phosphorylation of mitogen-activated protein kinase p38 were also found in the metastatic lung tissues treated with CytD and in the B16 cells co-cultured with CytD and factor VIIa (FVIIa), but not in cells cultured with CytD, dimethyl sulfoxide or FVIIa alone. These results indicate that CytD stimulates the expression of TF in B16 melanoma cells, activating both coagulation-dependent and -independent pathways via binding to FVIIa, eventually promoting lung metastasis. TF interference is a potential approach to the prevention of B16 melanoma metastasis.

Enhanced tumor suppression by adenoviral PTEN gene therapy combined with cisplatin chemotherapy in small-cell lung cancer

DNA-damaging anticancer drug cisplatin (cis-diamminedichloroplatinum) (DDP)-based chemotherapy is the mainstay and standard treatment for small-cell lung cancer (SCLC). However, frequent relapse and chemoresistance of SCLC remains a significant therapeutic hurdle. Tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) as a negative regulator of phosphoinositide 3-kinase/AKT survival pathway exhibits strong tumor-suppressive activities. A combination of chemotherapy and gene therapy (chemogene therapy) is a promising practice in cancer therapy. In this report, we examined the combined antitumor effect of adenovirus-mediated PTEN (AdVPTEN) gene therapy and DDP chemotherapy on PTEN-null NCI-H446 human SCLC cells in vitro and in vivo in athymic BALB/c nude mice. We demonstrated that AdVPTEN plus DDP enhanced growth suppression, cell-cycle G1 phase arrest and apoptosis in in vitro NCI-H446 tumor cells and in vivo NCI-H446 xenografted tumors subcutaneously inoculated in nude mice. Mechanistically, AdVPTEN plus DDP exerted an overlapping effect on upregulation of P53, P21, P27, Bax and Cleaved Caspase-3 as well as downregulation of Bcl-2 and survivin in in vitro and in vivo NCI-H446 tumor cells. Moreover, AdVPTEN plus DDP additively reduced tumor vessel CD34 expression and microvessel density in vivo. The enhanced therapeutic efficacy elicited by AdVPTEN plus DDP was closely associated with additive induction of G1 phase arrest and apoptosis via substantially modulating cell-cycle regulation molecules and activating intrinsic apoptotic pathway through P53 restoration, and overlapping inhibition of tumor angiogenesis. Thus, our results indicated that AdVPTEN combined with DDP may be a novel and effective chemogene therapy modality for human SCLC.

Endoglin for tumor imaging and targeted cancer therapy

INTRODUCTION

Although cancer treatment has evolved substantially in the past decades, cancer-related mortality rates are still increasing. Therapies targeting tumor angiogenesis, crucial for the growth of solid tumors, mainly target vascular endothelial growth factor (VEGF) and have been clinically applied during the last decade. However, these therapies have not met high expectations, which were based on therapeutic efficacy in animal models. This can partly be explained by the upregulation of alternative angiogenic pathways. Therefore, additional therapies targeting other pro-angiogenic pathways are needed.

AREAS COVERED

The transforming growth factor (TGF)-β signaling pathway plays an important role in (tumor) angiogenesis. Therefore, components of this pathway are interesting candidates for anti-angiogenic therapy. Endoglin, a co-receptor for various TGF-β family members, is specifically overexpressed in tumor vessels and endoglin expression is associated with metastasis and patient survival. Therefore, endoglin might be a good candidate for anti-angiogenic therapy. In this review, we discuss the potential of using endoglin to target the tumor vasculature for imaging and therapeutic purposes.

EXPERT OPINION

Considering the promising results from various in vitro studies, in vivo animal models and the first clinical trial targeting endoglin, we are convinced that endoglin is a valuable tool for the diagnosis, visualization and ultimately treatment of solid cancers.

Immunomodulatory effects of low dose chemotherapy and perspectives of its combination with immunotherapy

Given that cancer is one of the main causes of death worldwide, many efforts have been directed toward discovering new treatments and approaches to cure or control this group of diseases. Chemotherapy is the main treatment for cancer; however, a conventional schedule based on maximum tolerated dose (MTD) shows several side effects and frequently allows the development of drug resistance. On the other side, low dose chemotherapy involves antiangiogenic and immunomodulatory processes that help host to fight against tumor cells, with lower grade of side effects. In this review, we present evidence that metronomic chemotherapy, based on the frequent administration of low or intermediate doses of chemotherapeutics, can be better than or as efficient as MTD. Finally, we present some data indicating that noncytotoxic concentrations of antineoplastic agents are able to both up-regulate the immune system and increase the susceptibility of tumor cells to cytotoxic T lymphocytes. Taken together, data from the literature provides us with sufficient evidence that low concentrations of selected chemotherapeutic agents, rather than conventional high doses, should be evaluated in combination with immunotherapy.

Modification of cyclic NGR tumor neovasculature-homing motif sequence to human plasminogen kringle 5 improves inhibition of tumor growth

BACKGROUND

Blood vessels in tumors express higher level of aminopeptidase N (APN) than normal tissues. Evidence suggests that the CNGRC motif is an APN ligand which targets tumor vasculature. Increased expression of APN in tumor vascular endothelium, therefore, offers an opportunity for targeted delivery of NGR peptide-linked drugs to tumors.

METHODS/PRINCIPAL FINDINGS

To determine whether an additional cyclic CNGRC sequence could improve endothelial cell homing and antitumor effect, human plasminogen kringle 5 (hPK5) was modified genetically to introduce a CNGRC motif (NGR-hPK5) and was subsequently expressed in yeast. The biological activity of NGR-hPK5 was assessed and compared with that of wild-type hPK5, in vitro and in vivo. NGR-hPK5 showed more potent antiangiogenic activity than wild-type hPK5: the former had a stronger inhibitory effect on proliferation, migration and cord formation of vascular endothelial cells, and produced a stronger antiangiogenic response in the CAM assay. To evaluate the tumor-targeting ability, both wild-type hPK5 and NGR-hPK5 were (99 m)Tc-labeled, for tracking biodistribution in the in vivo tumor model. By planar imaging and biodistribution analyses of major organs, NGR-hPK5 was found localized to tumor tissues at a higher level than wild-type hPK5 (approximately 3-fold). Finally, the effects of wild-type hPK5 and NGR-modified hPK5 on tumor growth were investigated in two tumor model systems. NGR modification improved tumor localization and, as a consequence, effectively inhibited the growth of mouse Lewis lung carcinoma (LLC) and human colorectal adenocarcinoma (Colo 205) cells in tumor-bearing mice.

CONCLUSIONS/SIGNIFICANCE

These studies indicated that the addition of an APN targeting peptide NGR sequence could improve the ability of hPK5 to inhibit angiogenesis and tumor growth.

Therapeutic antitumor potential of endoglin-based DNA vaccine combined with immunomodulatory agents

Therapy targeting tumor blood vessels ought to inhibit tumor growth. However, tumors become refractory to antiangiogenic drugs. Therefore, therapeutic solutions should be sought to address cellular resistance to antiangiogenic therapy. In this regard, reversal of the proangiogenic and immunosuppressive phenotype of cancer cells, and the shift of the tumor microenvironment towards more antiangiogenic and immune-stimulating phenotype may hold some promise. In our study, we sought to validate the effects of a combination therapy aimed at reducing tumor blood vessels, coupled with the abrogation of the immunosuppressive state. To achieve this, we developed an oral DNA vaccine against endoglin. This antigen was carried by an attenuated Salmonella Typhimurium and applied before or after tumor cell inoculation into immunocompetent mice. Our results show that this DNA vaccine effectively inhibited tumor growth, in both the prophylactic and therapeutic settings. It also activated both specific and nonspecific immune responses in immunized mice. Activated cytotoxic T-lymphocytes were directed specifically against endothelial and tumor cells overexpressing endoglin. The DNA vaccine inhibited angiogenesis but did not affect wound healing. In combination with interleukin-12-mediated gene therapy, or with cyclophosphamide administration, the DNA vaccine resulted in reduced microvessel density and lowered the level of Treg lymphocytes in the experimental tumors. This effectively inhibited tumor growth and prolonged survival of the treated animals. Polarization of tumor milieu, from proangiogenic and immunosuppressive, towards an immunostimulatory and antiangiogenic profile represents a promising avenue in anticancer therapy.

Toxicarioside A, isolated from tropical Antiaris toxicaria, blocks endoglin/TGF-β signaling in a bone marrow stromal cell line

OBJECTIVE

To investigate possible mechanism of toxicarioside A in HS-5 bone stromal cells.

METHODS

HS-5 bone stromal cells were cultured in media supplemented with various concentrations of toxicarioside A or control DMSO (not treatment). Endoglin and TGF-β were detected by Northern and Western blot analysis and quantified in a standard method. Downstream molecules of endoglin and TGF-β (Smad1, Smad2 and their active phosphorylated counterparts, pSmad1 and pSmad2) were also detected and quantified by Western blot analysis. In addition, cell proliferation assay and small interfering RNA (siRNA) against endoglin were used to certificate the function of endolgin in the HS-5 cells.

RESULTS

Compared with the not treated (0 μg/mL) or DMSO treated control HS-5 cells, HS-5 cells treated with toxicarioside A were found significant attenuation of endolgin and TGF-β expression. Significant inhibition of cell proliferation was also found in the HS-5 cells treated with toxicarioside A. ALK1-related Smad1 and ALK5-related Smad2 were decreased in HS-5 cells treated with toxicarioside A. In addition, phosphorylated Smad1 (pSmad1) and Smad2 (pSmad2) were also found attenuation in toxicarioside A-treated HS-5 cells. RNA interference showed that blockage of endoglin by siRNA also decreased Smad1 and Smad2 expression in HS-5 cells.

CONCLUSIONS

Our results indicate that toxicarioside A can influence bone marrow stromal HS-5's function and inhibit HS-5 cell proliferation by alteration of endoglin-related ALK1 (Smad1) and ALK5 (Smad2) signaling.

The antitumour activities induced by pegylated liposomal cytochalasin D in murine models

Cytochalasin D targets actin and is ubiquitous in eukaryotic cells. When cytochalasin D is used as a cytotoxic agent in cancer therapy, it causes significant side effects. To prevent this, cytochalasin D can be encapsulated in polyethylene liposomes. In this study, high-performance liquid chromatography observation of the biodistribution of pegylated liposomal cytochalasin D in tumour-bearing mice showed that liposomal cytochalasin D could be conveniently dissolved in water for i.v. injection and that it specifically accumulated in tumour tissues, more than natural cytochalasin D did. The half-time of liposomal cytochalasin D in the plasma was also significantly longer than that of natural cytochalasin D (4h versus 10 min). MTT 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that liposomal cytochalasin D treatment could cause significant inhibition of cell proliferation in vitro in a manner similar to that of natural cytochalasin D. The antitumour activities of liposomal cytochalasin D were investigated in B16 melanoma, CT26 colorectal carcinoma and H22 hepatoma models, and the results indicated that liposomal cytochalasin D could significantly inhibit tumour growth and prolong survival in a manner similar to that of cisplatin. TUNEL-based apoptosis assays showed that liposomal cytochalasin D induced significant tumour cell apoptosis. Significant inhibition of tumour angiogenesis was observed in mice treated with liposomal cytochalasin D. In addition, no significant side effects were observed in mice treated with liposomal cytochalasin D. Our results show that liposomal cytochalasin D increases solubility and bioavailability, a lower incidence of side effects and improves antitumour effects, indicating its potential as a chemical agent for cancer therapy.

Cisplatin pretreatment enhances anti-tumor activity of cytokine-induced killer cells

AIM: To investigate whether cisplatin (DDP) enhances the anti-tumor activity of cytokine- induced killer (CIK) cells in a murine colon adenocarcinoma model.

METHODS: Tumor size and weight served as indicators of therapeutic response. Immunohistochemistry was performed to observe intratumoral lymphocyte infiltration and tumor microvessel density. Changes in the percentage of regulatory T (Treg) cells within the spleens of tumor-bearing mice preconditioned with DDP were monitored using flow cytometry.

RESULTS: A marked T cell-dependent, synergistic anti-tumor effect of the combined therapy was observed (1968 ± 491 mm³ vs 3872 ± 216 mm³; P = 0.003). Preconditioning chemotherapy with DDP augmented the infiltration of CD3+ T lymphocytes into the tumor mass and reduced the percentage of both intratumoral and splenic Treg cells.

CONCLUSION: Preconditioning with DDP markedly enhances the efficacy of adoptively transferred CIK cells, providing a potential clinical modality for the treatment of patients with colorectal cancer.

Vaccines targeting the neovasculature of tumors

Angiogenesis has a critical role in physiologic and disease processes. For the growth of tumors, angiogenesis must occur to carry sufficient nutrients to the tumor. In addition to growth, development of new blood vessels is necessary for invasion and metastases of the tumor. A number of strategies have been developed to inhibit tumor angiogenesis and further understanding of the interplay between tumors and angiogenesis should allow new approaches and advances in angiogenic therapy. One such promising angiogenic approach is to target and inhibit angiogenesis with vaccines. This review will discuss recent advances and future prospects in vaccines targeting aberrant angiogenesis of tumors. The strategies utilized by investigators have included whole endothelial cell vaccines as well as vaccines with defined targets on endothelial cells and pericytes of the developing tumor endothelium. To date, several promising anti-angiogenic vaccine strategies have demonstrated marked inhibition of tumor growth in pre-clinical trials with some showing no observed interference with physiologic angiogenic processes such as wound healing and fertility.

Enhanced antitumor activity by combining an adenovirus harboring ING4 with cisplatin for hepatocarcinoma cells

The inhibitor of growth (ING) family proteins have been defined as candidate tumor suppressors. ING4 as a novel member of the ING family has potential tumor-suppressive effects. In this study, we explored the combined effect of adenovirus-mediated ING4 (Ad-ING4) gene transfer plus chemotherapy drug cisplatin (CDDP) on SMMC-7721 human hepatocarcinoma cells in vitro and in vivo, and its underlying mechanism. We demonstrated that Ad-ING4 plus CDDP induced synergistic growth inhibition, enhanced apoptosis, and had an additive effect on upregulation of Fas, Bax, Bak, cleaved Bid, cleaved caspase-8, caspase-9, caspase-3 and cleaved PARP, and on downregulation of Bcl-2 and Bcl-X_L in SMMC-7721 hepatocarcinoma cells. Moreover, Ad-ING4 plus CDDP synergistically suppressed in vivo SMMC-7721 hepatocarcinoma subcutaneous (s.c.) xenografted tumor growth and reduced tumor vessel CD34 expression and microvessel density (MVD) in athymic nude mice. Most importantly, Ad-ING4 plus CDDP did not have overlapping toxicities in HL-7702 normal human liver cells and normal liver tissues of mice. The in vitro and in vivo enhanced antitumor effect elicited by Ad-ING4 plus CDDP was closely associated with the cooperative regulation of extrinsic and intrinsic apoptotic pathways and synergistic inhibition of tumor angiogenesis. Thus, our results indicate that Ad-ING4 plus CDDP is a potential combined treatment strategy for hepatocarcinoma.

CD105 is a marker of tumour vasculature and a potential target for the treatment of head and neck squamous cell carcinoma

BACKGROUND

The importance of angiogenesis in solid tumour growth is well recognised. Tumour angiogenesis is considered the result of an imbalance between pro- and anti-angiogenic factors produced by both the malignancy and normal cells. Endoglin (CD105) is a proliferation-associated, hypoxia-inducible glycoprotein that seems to be clinically superior to other pan-endothelial markers in the selective evaluation of tumour angiogenesis. Several studies have revealed CD105 up-regulation in a wide range of tumour endothelia. Since 2002, endothelial CD105 expression has also been retrospectively investigated in patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

An exhaustive literature review was performed to investigate available evidence on CD105 expression and its biological role and therapeutic potential in HNSCC.

RESULTS

The available evidence supports the hypothesis that CD105 expression in HNSCC may be a valuable parameter for pinpointing patients at greater risk of recurrent malignancy and with a worse prognosis. A high CD105 expression in HNSCC was associated with metastatic lymph nodes in most of the studies.

CONCLUSIONS

Prospective studies are mandatory to confirm that CD105 expression is a significant prognostic hallmark in HNSCC. The results of prospective studies could be relevant for the adoption of stricter follow-up protocols and/or alternative therapeutic regimens for patients with a high CD105 expression in HNSCC. Great interest is currently being focused on vascular targeting for therapeutic purposes. Preclinical studies on appropriate animal models resembling HNSCC to investigate the effects of inhibiting CD105 may show the efficacy of combined treatment strategies associating angiogenic-targeted with conventional therapies for HNSCC.

Immunotherapy combined with chemotherapy in the treatment of tumors

This article provides a broad overview of the data, including laboratory and clinical studies, currently available on the combination of immunotherapy and chemotherapy for treating cancer. The various forms of immunotherapy combined with chemotherapy include monoclonal antibodies, adoptive lymphocyte transfer, or active specific immunotherapy, such as tumor proteins, irradiated tumor cells, tumor cell lysates, dendritic cells pulsed with peptides or lysates, or tumor antigens expressed in plasmids or viral vectors. This discussion is not limited to malignant brain tumors, because many of the studies have been conducted on various cancer types, thereby providing a comprehensive perspective that may encourage further studies that combine chemotherapy and immunotherapy for treating brain tumors.

The emerging role of TGF-beta superfamily coreceptors in cancer

The transforming growth factor beta (TGF-beta) signaling pathway plays a key role in different physiological processes such as development, cellular proliferation, extracellular matrix synthesis, angiogenesis or immune responses and its deregulation may result in tumor development. The TGF-beta coreceptors endoglin and betaglycan are emerging as modulators of the TGF-beta response with important roles in cancer. Endoglin is highly expressed in the tumor-associated vascular endothelium with prognostic significance in selected neoplasias and with potential to be a prime vascular target for antiangiogenic cancer therapy. On the other hand, the expression of endoglin and betaglycan in tumor cells themselves appears to play an important role in the progression of cancer, influencing cell proliferation, motility, invasiveness and tumorigenicity. In addition, experiments in vitro and in vivo in which endoglin or betaglycan expression is modulated have provided evidence that they act as tumor suppressors. The purpose of this review was to highlight the potential of membrane and soluble forms of the endoglin and betaglycan proteins as molecular targets in cancer diagnosis and therapy.

Combination of Recombinant Xenogeneic Endoglin DNA and Protein Vaccination Enhances Anti-tumor Effects

The immunization approaches with DNA vaccine priming and subsequent protein or peptide boosting has been widely tested in various models of infectious diseases. However, these approaches are seldom reported in the areas of cancer immunotherapy. In this study we combined endoglin plasmid DNA and recombinant protein as vaccines and used them to prime and boost, simultaneously, as a vaccine strategy. Our results showed that combination of endoglin DNA and protein vaccines could enhance both protective and therapeutic anti-tumor efficacy in both colon carcinoma and Lewis lung carcinoma models. Significant inhibition of tumor angiogenesis was found in the tumor tissues. The titers of autoantibodies against murine endoglin were significantly increased and the antibody levels lasted longer in the mice with combined endoglin DNA and recombinant protein vaccination. CTL response against endoglin-positive HUVECs, but not against endoglin-negative tumor cells was found in the mice combined DNA with protein vaccination. In addition, combination of endoglin DNA and recombinant protein vaccination significantly induced IFN-gamma secreting cells. These observations suggested that a combination of endoglin DNA and recombinant protein immunization as a vaccine strategy was superior to those using endoglin DNA or recombinant protein alone as vaccines.

Combination of active specific immunotherapy or adoptive antibody or lymphocyte immunotherapy with chemotherapy in the treatment of cancer

Successful treatment of cancer patients with a combination of monoclonal antibodies (mAb) and chemotherapeutic drugs has spawned various other forms of additional combination therapies, including vaccines or adoptive lymphocyte transfer combined with chemotherapeutics. These therapies were effective against established tumors in animal models and showed promising results in initial clinical trials in cancer patients, awaiting testing in larger randomized controlled studies. Although combination between immunotherapy and chemotherapy has long been viewed as incompatible as chemotherapy, especially in high doses meant to increase anti-tumor efficacy, has induced immunosuppression, various mechanisms may explain the reported synergistic effects of the two types of therapies. Thus direct effects of chemotherapy on tumor or host environment, such as induction of tumor cell death, elimination of regulatory T cells, and/or enhancement of tumor cell sensitivity to lysis by CTL may account for enhancement of immunotherapy by chemotherapy. Furthermore, induction of lymphopenia by chemotherapy has increased the efficacy of adoptive lymphocyte transfer in cancer patients. On the other hand, immunotherapy may directly modulate the tumor's sensitivity to chemotherapy. Thus, anti-tumor mAb can increase the sensitivity of tumor cells to chemotherapeutic drugs and patients treated first with immunotherapy followed by chemotherapy showed higher clinical response rates than patients that had received chemotherapy alone. In conclusion, combination of active specific immunotherapy or adoptive mAb or lymphocyte immunotherapy with chemotherapy has great potential for the treatment of cancer patients which needs to be confirmed in larger controlled and randomized Phase III trials.

Low-dose paclitaxel prior to intratumoral dendritic cell vaccine modulates intratumoral cytokine network and lung cancer growth

PURPOSE

The main goal of this study was to provide the "proof-of-principle" that low-dose paclitaxel is able to change the tumor microenvironment and improve the outcome of intratumoral dendritic cell vaccine in a murine lung cancer model.

EXPERIMENTAL DESIGN

We evaluated the antitumor potential and changes in the intratumoral milieu of a combination of low-dose chemotherapy and dendritic cell vaccine in the Lewis lung carcinoma model in vivo.

RESULTS

The low-dose paclitaxel, which induced apoptosis in approximately 10% of tumor cells, was not toxic to bone marrow cells and dendritic cells and stimulated dendritic cell maturation and function in vitro. Although tumor cells inhibited dendritic cell differentiation in vitro, this immunosuppressive effect was abrogated by the pretreatment of tumor cells with low-dose paclitaxel. Based on these data, we next tested whether pretreatment of tumor-bearing mice with low-dose paclitaxel in vivo would improve the antitumor potential of dendritic cell vaccine administered intratumorally. Significant inhibition of tumor growth in mice treated with low-dose paclitaxel plus intratumoral dendritic cell vaccine, associated with increased tumor infiltration by CD4(+) and CD8(+) T cells and elevated tumor-specific IFN-gamma production by draining lymph node cells, was revealed. Using a novel intratumoral microdialysis technique and Luminex technology for collecting and characterizing soluble factors released within the tumor bed for several days in live freely moving animals, we showed that low-dose paclitaxel altered the cytokine network at the tumor site.

CONCLUSIONS

Our data indicate that low-dose chemotherapy before intratumoral delivery of dendritic cells might be associated with beneficial alterations of the intratumoral microenvironment and thus support antitumor immunity.

Extracellular control of TGFbeta signalling in vascular development and disease

The intracellular mechanism of transforming growth factor-beta (TGFbeta) signalling via kinase receptors and SMAD effectors is firmly established, but recent studies of human cardiovascular syndromes such as Marfan syndrome and pre-eclampsia have refocused attention on the importance of regulating the availability of active extracellular TGFbeta. It seems that elastic extracellular matrix (ECM) components have a crucial role in controlling TGFbeta signalling, while soluble and membrane bound forms of TGFbeta co-receptors add further layers of regulation. Together, these extracellular interactions determine the final bioavailability of TGFbeta to vascular cells, and dysregulation is associated with an increasing number of vascular pathologies.

Combination of MIG (CXCL9) chemokine gene therapy with low-dose cisplatin improves therapeutic efficacy against murine carcinoma

MIG (monokine induced by interferon-gamma) is a CXC chemokine ligand (CXCL9) that can potently inhibit angiogenesis, and displays thymus-dependent antitumor effects. The effectiveness of a treatment combining gene therapy with plasmid-borne MIG (pORF-MIG) and low-dose cisplatin chemotherapy was determined using colon carcinoma (CT26) and Lewis lung carcinoma (LL/2c) murine models. The program was carried out via intramuscular delivery of pORF-MIG at 100 mug/mouse twice a week for 4 weeks, and/or intraperitoneal delivery of cisplatin at 0.6 mg/kg/mouse every 3 days for 48 days. Tumor volume and survival time were evaluated after treatment. CD31 immunohistochemical staining in tumor tissues and alginate capsule models in vivo was used to evaluate angiogenesis. Induction of apoptosis and cytotoxic T-lymphocyte (CTL) activity were also assessed. The combination of pORF-MIG and low-dose cisplatin produced significant antitumor activity, with complete tumor regression in 4/10 of CT26 colon carcinomas and 3/10 of LL/2c lung carcinomas, low vascularity, in alginate capsules, apparently degraded tumor microvessel density, and increased induction of apoptotic and CTL activities compared with either treatment alone. This study suggests that the combination of pORF-MIG plus cisplatin augments the inhibition of angiogenesis and the induction of apoptosis or CTL activity, all of which enhance antitumor activity. These findings may prove useful in further explorations of the application of combinatorial approaches to the treatment of solid tumors.

Tumor stroma-associated antigens for anti-cancer immunotherapy

Immunotherapy has been widely investigated for its potential use in cancer therapy and it becomes more and more apparent that the selection of target antigens is essential for its efficacy. Indeed, limited clinical efficacy is partly due to immune evasion mechanisms of neoplastic cells, e.g. downregulation of expression or presentation of the respective antigens. Consequently, antigens contributing to tumor cell survival seem to be more suitable therapeutic targets. However, even such antigens may be subject to immune evasion due to impaired processing and cell surface expression. Since development and progression of tumors is not only dependent on cancer cells themselves but also on the active contribution of the stromal cells, e.g. by secreting growth supporting factors, enzymes degrading the extracellular matrix or angiogenic factors, the tumor stroma may also serve as a target for immune intervention. To this end several antigens have been identified which are induced or upregulated on the tumor stroma. Tumor stroma-associated antigens are characterized by an otherwise restricted expression pattern, particularly with respect to differentiated tissues, and they have been successfully targeted by passive and active immunotherapy in preclinical models. Moreover, some of these strategies have already been translated into clinical trials.

Vaccines targeting tumour angiogenesis--a novel strategy for cancer immunotherapy

AIMS

To review the concept of tumour angiogenesis and anti-angiogenic therapy, limitations of recently used anti-angiogenic therapeutics; provide an up-to-date overview of the growing number of reports on vaccines targeting tumour angiogenesis; and finally discuss potential complications and future directions in the development of more potent and specific vaccines.

METHODS

A literature search was carried out from PubMed for indexed articles. The most important articles were analysed and discussed.

FINDINGS

The search yielded a large number of important indexed published articles that were reviewed, screened and tracked for other relevant publications. The most relevant articles, including those previously published by authors, were analysed and discussed.

CONCLUSIONS

Recently, different vaccine strategies have been reported to inhibit tumour growth and metastasis by induction of specific cellular and/or humoral immunity against angiogenesis-associated antigens in pre-clinical models, suggesting effective combination of anti-angiogenesis and cancer immunotherapy. Evaluation of tumour endothelial cells and clinical phase I study of the vaccines are recently ongoing, and should give us better insight into the possibilities of this novel strategy for cancer immunotherapy.

Systemic administration of attenuated Salmonella choleraesuis in combination with cisplatin for cancer therapy

Some anaerobic and facultative anaerobic bacteria have been employed as anticancer agents. Previously, we have demonstrated tumor-targeting and antitumor activities of attenuated Salmonella choleraesuis carrying antiangiogenic genes. Here we exploited S. choleraesuis as a single-agent therapy and as part of a combination therapy with low-dose cisplatin for syngeneic murine lung tumor and hepatoma. Systemically injected S. choleraesuis preferentially accumulated within tumors for at least 4 weeks and the bacteria accumulated preferentially in not only subcutaneous but also orthotopic tumors over livers and spleens at ratios ranging from 1000:1 to 100,000:1. S. choleraesuis was capable of delaying tumor growth and enhancing survival in both subcutaneous tumor and experimental metastasis models. More strikingly, the combination of S. choleraesuis plus cisplatin acted additively to retard tumor growth and extensively prolong the survival time of the mice bearing hepatomas or lung tumors. Such combination treatment also increased infiltrating neutrophils and CD8+ T cells, as well as apoptotic cells, in the tumors, compared with S. choleraesuis or cisplatin treatment alone. These findings suggest that S. choleraesuis in combination with cisplatin, which exerts oncolytic effects and enhances antitumor immune responses, represents a promising strategy for the treatment of primary and metastatic tumors.