VEGF as a mediator of tumor-associated immunodeficiency

Dendritic cells transfected with hepatocellular carcinoma (HCC) total RNA induce specific immune responses against HCC in vitro and in vivo

BACKGROUND

Immunotherapy is an effective method for preventing metastasis and recurrence of carcinoma. Hepatocellular carcinoma (HCC) is a common malignancy with a high rate of recurrence, and has not successfully been introduced to immunotherapy.

METHODS

Peripheral blood mononuclear cells were isolated from whole blood of HCC patients and stimulated to transform into dendritic cells (DCs). These DCs were then transfected with RNA extracted from HepG-2 hepatoma cells to induce expression of specific antigens.

RESULTS

The transfected DCs stimulated T lymphocytes to produce cytotoxic T lymphocytes, which specifically attacked HepG-2 cells. Injection of T lymphocytes from HCC patients and transfected DCs into severe combined immunodeficiency mice limited the growth of HepG-2 tumors.

CONCLUSION

A specific immune response against hepatoma can be generated in vivo by administering DCs transfected with RNA from a specific tumor. This method may have therapeutic application in humans to reduce recurrence of HCC.

Structured myeloid cells and anti-angiogenic therapy in alveolar soft part sarcoma

Alveolar soft part sarcoma (ASPS) is a rare soft tissue sarcoma and the clinical management of patients with unresectable, metastatic disease is still challenging. ASPS expresses an array of potentially therapeutically targetable, angiogenesis-related molecules and, importantly, it has a distinctive angiogenic phenotype marked by a peculiar tumor-associated vasculature. Several studies, conducted in transgenic mouse models and in a large variety of human tumors of different histotype, clearly proved the substantial contribution of tumor-infiltrating myeloid cells, such as myeloid derived suppressor cells, monocytes and macrophages, in the formation and maintenance of abnormal blood vessels in tumors. By immunohistochemistry we thus explored the presence and the distribution of cells expressing myeloid markers in the inflammatory infiltrate of surgical treated metastatic ASPS. Indeed, we found that myeloid cells expressing CD14 and CD163 markers constitute the prominent cells in the inflammatory infiltrate of ASPS. These macrophage-like cells form a network surrounding the endothelial cells, or, interspersed in the tumor nest, they keep deep contact with tumor cells. In this commentary, we discussed our findings in relation to the recently published paper by Kummar and colleagues reporting the clinical and molecular results of a phase II clinical trial in patients with unresectable, metastatic ASPS treated with the anti-angiogenic drug cediranib, targeting the VEGFR-1,-2,-3 tyrosine kinases.

Dendritic cells in cancer immunotherapy: vaccines and combination immunotherapies

Dendritic cells (DCs) are specialized immunostimulatory cells involved in the induction and regulation of immune responses. The feasibility of large-scale ex vivo generation of DCs from patients' monocytes allows for therapeutic application of ex vivo-cultured DCs to bypass the dysfunction of endogenous DCs, restore immune surveillance, induce cancer regression or stabilization or delay or prevent its recurrence. While the most common paradigm of the therapeutic application of DCs reflects their use as cancer 'vaccines', additional and potentially more effective possibilities include the use of patients' autologous DCs as parts of more comprehensive therapies involving in vivo or ex vivo induction of tumor-reactive T cells and the measures to counteract systemic and local immunosuppression in tumor-bearing hosts. Ex vivo-cultured DCs can be instructed to acquire distinct functions relevant for the induction of effective cancer immunity (DC polarization), such as the induction of different effector functions or different homing properties of tumor-specific T cells (delivery of 'signal 3' and 'signal 4'). These considerations highlight the importance of the application of optimized conditions for the ex vivo culture of DCs and the potential combination of DC therapies with additional immune interventions to facilitate the entry of DC-induced T cells to tumor tissues and their local antitumor functions.

Characteristics and clinical impacts of the immune environments in colorectal and renal cell carcinoma lung metastases: influence of tumor origin

PURPOSE

If immune cells are involved in tumor surveillance and have a prognostic impact in most primary tumors, little is known about their significance in metastases. Because patients' survival is heterogeneous, even at metastatic stages, we hypothesized that immune cells may be involved in the control of metastases. We therefore characterized the tumor immune microenvironment and its prognostic value in colorectal and renal cell carcinoma (RCC) metastases, and compared it to primary tumors.

EXPERIMENTAL DESIGN

We analyzed by immunohistochemistry (n = 192) and qPCR (n = 32) the immune environments of colorectal carcinoma and RCC lung metastases.

RESULTS

Metastases from colorectal carcinoma and RCC have different immune infiltrates. Higher densities of DC-LAMP(+) mature dendritic cells (P < 0.0001) and lower densities of NKp46(+) NK cells (P < 0.0001) were observed in colorectal carcinoma as compared to RCC metastases, whereas densities of T cells were similar. High densities of CD8(+) and DC-LAMP(+) cells correlated with longer overall survival (OS) in colorectal carcinoma (P = 0.008) and shorter OS in RCC (P < 0.0001). High NK-cell densities were associated with improved survival in RCC (P = 0.002) but not in colorectal carcinoma. Densities of immune cells correlated significantly from primary to relapsing metastases for the same patient. A TH1 orientation was found in colorectal carcinoma metastases, whereas a heterogeneous immune gene expression was found in RCC metastases.

CONCLUSIONS

Our results show a major prognostic value of the immune pattern (CD8(+)/DC-LAMP(+) cell densities) in colorectal carcinoma and RCC, reproducible from primary to metastatic tumors, although with opposite clinical impacts, and highlight the role of the tumor cell in shaping its immune environment.

A Phase I vaccine trial using dendritic cells pulsed with autologous oxidized lysate for recurrent ovarian cancer

PURPOSE

Ovarian cancer, like most solid tumors, is in dire need of effective therapies. The significance of this trial lies in its promise to spearhead the development of combination immunotherapy and to introduce novel approaches to therapeutic immunomodulation, which could enable otherwise ineffective vaccines to achieve clinical efficacy.

RATIONALE

Tumor-infiltrating T cells have been associated with improved outcome in ovarian cancer, suggesting that activation of antitumor immunity will improve survival. However, molecularly defined vaccines have been generally disappointing. Cancer vaccines elicit a modest frequency of low-to-moderate avidity tumor-specific T-cells, but powerful tumor barriers dampen the engraftment, expansion and function of these effector T-cells in the tumor, thus preventing them from reaching their full therapeutic potential. Our work has identified two important barriers in the tumor microenvironment: the blood-tumor barrier, which prevents homing of effector T cells, and T regulatory cells, which inactivate effector T cells. We hypothesize that cancer vaccine therapy will benefit from combinations that attenuate these two barrier mechanisms.

DESIGN

We propose a three-cohort sequential study to investigate a combinatorial approach of a new dendritic cell (DC) vaccine pulsed with autologous whole tumor oxidized lysate, in combination with antiangiogenesis therapy (bevacizumab) and metronomic cyclophosphamide, which impacts Treg cells.

INNOVATION

This study uses a novel autologous tumor vaccine developed with 4-day DCs pulsed with oxidized lysate to elicit antitumor response. Furthermore, the combination of bevacizumab with a whole tumor antigen vaccine has not been tested in the clinic. Finally the combination of bevacizumab and metronomic cyclophosphamide in immunotherapy is novel.

Prognostic and predictive value of serum vascular endothelial growth factor (VEGF) in squamous cell carcinoma of the head and neck

INTRODUCTION

This study aimed to investigate the prognostic and predictive value of serum vascular endothelial growth factor (VEGF) in head and neck squamous cell carcinoma (HNSCC).

METHOD

Preoperative and 6-month postoperative serum VEGF levels were measured using a quantitative sandwich enzyme immunoassay technique in 55 consecutive patients with HNSCC and two control groups. The first control group included normal, healthy, age- and sex-matched individuals (n = 20), while the second control group included the patients who had history of HNSCC and were free of disease for at least 5 years (n = 25).

RESULTS

The mean baseline serum VEGF concentrations of the 55 patients with HNSCC and the first and the second control groups were 437.86, 42.56, and 48.03 pg/ml, respectively (P < 0.001). After a median follow-up of 75 months, 15 patients of the study group developed recurrent disease and 40 patients remained free of disease. The mean preoperative and 6-month postoperative serum VEGF levels for the 40 patients who did not have recurrent disease were respectively 327.69 and 153.50 pg/ml compared to 731.72 and 692.96 pg/ml for the 15 patients with recurrent disease (P < 0.001). High (≥540 pg/ml) serum VEGF level was associated with poor overall survival (P < 0.001). Moreover, multivariate analysis showed node stage (P < 0.001) and preoperative serum VEGF level (P = 0.020) as significant, independent prognostic factors for overall survival.

CONCLUSION

Preoperative or postoperative elevated serum levels of VEGF are highly predictive for disease recurrence and are associated with poor disease-free and overall survival of patients with HNSCC.

Predictive value of vascular endothelial growth factor overexpression in early relapse of colorectal cancer patients after curative resection

BACKGROUND

Preclinical and clinical studies have indicated that vascular endothelial growth factor (VEGF) is the predominant angiogenic factor. Recently, there was a consistent trend of poorer survival rates in colorectal cancer (CRC) patients of earlier relapse. The purpose of this study was to investigate novel predictors of early relapse in stage I-III CRC and further to determine their correlation with disease outcomes.

MATERIALS AND METHODS

We retrospectively analyzed clinicopathological features and VEGF expression by immunohistochemical staining in 100 stage I-III CRC patients undergoing curative resection to identify predictors of postoperative early relapse.

RESULTS

Among 100 patients, 40 patients were classified into early relapse group, and 60 patients were categorized into non-early relapse group. A multivariate logistic regression analysis showed that vascular invasion (P = 0.048), perineural invasion (P = 0.042), VEGF overexpression (P = 0.023), and high postoperative carcinoembryonic antigen (CEA) levels (P = 0.004) were independent predictors of early relapse. Additionally, we found that with more predictors such as the combined incidence of vascular invasion, perineural invasion, VEGF overexpression, and postoperative CEA levels are involved, the incidence of early postoperative relapse increases. Moreover, VEGF overexpression predicted not only early postoperative relapse but also disease-free survival (P < 0.001) and overall survival (P = 0.002).

CONCLUSIONS

This study suggests that VEGF overexpression is an important predictor of early postoperative relapse in patients with stage I-III CRC and may help identify patients who would benefit from intensive follow-up and therapeutic programs.

Metabolism of L-arginine by myeloid-derived suppressor cells in cancer: mechanisms of T cell suppression and therapeutic perspectives

Patients with cancer have an impaired T cell response that can decrease the potential therapeutic benefit of cancer vaccines and other forms of immunotherapy. The establishment of a chronic inflammatory environment in patients with cancer plays a critical role in the induction of T cell dysfunction. The accumulation of myeloid-derived suppressor cells (MDSC) in tumor bearing hosts is a hallmark of malignancy-associated inflammation and a major mediator of the induction of T cell suppression in cancer. Recent findings in tumor bearing mice and cancer patients indicate that the increased metabolism of L-Arginine (L-Arg) by MDSC producing Arginase I inhibits T cell lymphocyte responses. Here, we discuss some of the most recent concepts of how MDSC expressing Arginase I may regulate T cell function in cancer and suggest possible therapeutic interventions to overcome this inhibitory effect.

BRAF inhibition increases tumor infiltration by T cells and enhances the antitumor activity of adoptive immunotherapy in mice

PURPOSE

Treatment of melanoma patients with selective BRAF inhibitors results in objective clinical responses in the majority of patients with BRAF-mutant tumors. However, resistance to these inhibitors develops within a few months. In this study, we test the hypothesis that BRAF inhibition in combination with adoptive T-cell transfer (ACT) will be more effective at inducing long-term clinical regressions of BRAF-mutant tumors.

EXPERIMENTAL DESIGN

BRAF-mutated human melanoma tumor cell lines transduced to express gp100 and H-2D(b) to allow recognition by gp100-specific pmel-1 T cells were used as xenograft models to assess melanocyte differentiation antigen-independent enhancement of immune responses by BRAF inhibitor PLX4720. Luciferase-expressing pmel-1 T cells were generated to monitor T-cell migration in vivo. The expression of VEGF was determined by ELISA, protein array, and immunohistochemistry. Importantly, VEGF expression after BRAF inhibition was tested in a set of patient samples.

RESULTS

We found that administration of PLX4720 significantly increased tumor infiltration of adoptively transferred T cells in vivo and enhanced the antitumor activity of ACT. This increased T-cell infiltration was primarily mediated by the ability of PLX4720 to inhibit melanoma tumor cell production of VEGF by reducing the binding of c-myc to the VEGF promoter. Furthermore, analysis of human melanoma patient tumor biopsies before and during BRAF inhibitor treatment showed downregulation of VEGF consistent with the preclinical murine model.

CONCLUSION

These findings provide a strong rationale to evaluate the potential clinical application of combining BRAF inhibition with T-cell-based immunotherapy for the treatment of patients with melanoma.

Myeloid-derived suppressor cells interact with tumors in terms of myelopoiesis, tumorigenesis and immunosuppression: thick as thieves

Tumor progression is often associated with chronic inflammation in the tumor microenvironment, which is mediated by numerous cytokines, chemokines and growth factors produced by cancer and stroma cells. All these mediators support tumor development and immunosuppression in autocrine and/or paracrine ways. Neutralization of chronic inflammatory conditions can lead to the restoration of anti-tumor immune responses. Among stroma cells infiltrating tumors, myeloid-derived suppressor cells (MDSCs) represent one of the most important players mediating immunosuppression. These cells may not only inhibit an anti-tumor immunity but also directly stimulate tumorigenesis as well as tumor growth and expansion. Therefore, understanding the mechanisms of generation, migration to the tumor site and activation of MDSC is necessary for the development of new strategies of tumor immunotherapy.

BRAF inhibition increases tumor infiltration by T cells and enhances the antitumor activity of adoptive immunotherapy in mice

PURPOSE

Treatment of melanoma patients with selective BRAF inhibitors results in objective clinical responses in the majority of patients with BRAF-mutant tumors. However, resistance to these inhibitors develops within a few months. In this study, we test the hypothesis that BRAF inhibition in combination with adoptive T-cell transfer (ACT) will be more effective at inducing long-term clinical regressions of BRAF-mutant tumors.

EXPERIMENTAL DESIGN

BRAF-mutated human melanoma tumor cell lines transduced to express gp100 and H-2D(b) to allow recognition by gp100-specific pmel-1 T cells were used as xenograft models to assess melanocyte differentiation antigen-independent enhancement of immune responses by BRAF inhibitor PLX4720. Luciferase-expressing pmel-1 T cells were generated to monitor T-cell migration in vivo. The expression of VEGF was determined by ELISA, protein array, and immunohistochemistry. Importantly, VEGF expression after BRAF inhibition was tested in a set of patient samples.

RESULTS

We found that administration of PLX4720 significantly increased tumor infiltration of adoptively transferred T cells in vivo and enhanced the antitumor activity of ACT. This increased T-cell infiltration was primarily mediated by the ability of PLX4720 to inhibit melanoma tumor cell production of VEGF by reducing the binding of c-myc to the VEGF promoter. Furthermore, analysis of human melanoma patient tumor biopsies before and during BRAF inhibitor treatment showed downregulation of VEGF consistent with the preclinical murine model.

CONCLUSION

These findings provide a strong rationale to evaluate the potential clinical application of combining BRAF inhibition with T-cell-based immunotherapy for the treatment of patients with melanoma.

Intratumoral FOXP3+VEGFR2+ regulatory T cells are predictive markers for recurrence and survival in patients with colorectal cancer

Previously, we have shown that CD8(+)T/FOXP3(+) cell ratio but not FOXP3(+) cell number alone is an independent prognostic factor for colorectal cancer. In the present study, we evaluated whether the number of intratumoral FOXP3(+)VEGFR2(+) (itFOXP3(+)VEGFR2(+)) T cells alone could be a predictive factor for survival prognosis in patients with colorectal cancer. Distribution of regulatory T cells (Tregs) at tumor sites derived from 88 patients with primary colorectal cancer was fluorescence-immunohistochemically examined. Relatively low number of itFOXP3(+)VEGFR2(+) cells significantly correlated with better [corrected] disease-free survival (DS) and overall survival (OS); multivariate analysis indicated that number of itFOXP3(+)VEGFR2(+) cells is an independent predictive and prognostic factor of DS and OS while neither intratumoral FOXP3(+) cell number nor intratumoral FOXP3(+)VEGFR2(-) cell number alone showed significant correlation with DS or OS. These results suggest that FOXP3(+)VEGFR2(+) may be a better predictive Treg marker than FOXP3(+) alone for recurrence and survival in patients with colorectal cancer.

Myeloid-derived suppressor cells: mechanisms of action and recent advances in their role in transplant tolerance

Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of immature hematopoietic precursors known to suppress immune responses in infection, chronic inflammation, cancer, and autoimmunity. In this paper, we review recent findings detailing their mode of action and discuss recent reports that suggest that MDSC are also expanded during transplantation and that modulation of MDSC can participate in preventing graft rejection as well as graft-versus-host disease.

Concomitant targeting of tumor cells and induction of T-cell response synergizes to effectively inhibit trastuzumab-resistant breast cancer

Trastuzumab is an iconic rationally designed targeted therapy for HER2-positive breast cancers. However, the low response rate and development of resistance call for novel approaches for the treatment of patients. Here, we report that concurrent targeting of tumor cells and activation of T cells in the tumor microenvironment results in a synergistic inhibitory effect on tumor growth and overcomes resistance in two distinct PTEN loss-mediated trastuzumab-resistant mammary tumor mouse models. In vivo combination treatment with HER2/Neu antibody and Akt inhibitor triciribine effectively inhibited tumor growth in both models via inhibiting PI3K/AKT and mitogen-activated protein kinase signaling accompanied by increased T-cell infiltration in the tumor microenvironment. We showed that both CD8(+) and CD4(+) T cells were essential to the optimal antitumor effect of this combination treatment in an IFN-γ-dependent manner. Importantly, the antitumor activities of HER2/Neu antibody and triciribine combination treatment were further improved when coinhibitory receptor cytotoxic T-lymphocyte-associated antigen 4 was blocked to enhance the T-cell response. Our data indicate that multitargeted combinatorial therapies targeting tumor cells and concomitantly enhancing T-cell response in the tumor microenvironment could cooperate to exert maximal therapeutic activity, suggesting a promising clinical strategy for treating trastuzumab-resistant breast cancers and other advanced malignancies.

Anti-angiogenic therapy renders large tumors vulnerable to immunotherapy via reducing immunosuppression in the tumor microenvironment

We have recently demonstrated that a 4-in-1 gene therapy strategy that contains two anti-angiogenic genes [endostatin and pigment epithelium-derived factor] and two cytokine genes [granulocyte macrophage colony-stimulating factor and interleukin 12] has a considerable antitumor effect on large tumors in a woodchuck hepatoma model. The current study further investigates the underlying mechanisms for the antitumor effect observed by using small rodent models. We found that immunotherapy alone increased immunosuppressive cells in large tumors over time, whereas the anti-angiogenic therapy contained in the 4-in-1 strategy alleviated immunosuppression and made tumors vulnerable to immunotherapy, thus resulting in a synergistic antitumor effect.

Calreticulin promotes tumor lymphocyte infiltration and enhances the antitumor effects of immunotherapy by up-regulating the endothelial expression of adhesion molecules

Tumor-induced angiogenesis has been shown to suppress immune responses. One mechanism is to suppress leukocyte-endothelial cell interaction by down-regulating the expression of adhesion molecules, such as intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and E-selectin on the tumor endothelium, which enables tumor cells to escape immune surveillance. Calreticulin (CRT), a chaperone protein mainly located in the endoplasmic reticulum, has been shown to exert anti-angiogenic activity and inhibit tumor growth. Here, we demonstrate that in addition to inhibiting angiogenesis, CRT also enhances the expression of both ICAM-1 and VCAM-1 on tumor endothelial cells. This expression results in enhanced leukocyte-endothelial cell interactions and increased lymphocyte infiltration into tumors. Therefore, combining intramuscular CRT gene transfer with intratumoral cytokine gene therapies significantly improves the antitumor effects of immunotherapy by markedly increasing the levels of tumor-infiltrating lymphocytes. This combined treatment increased the levels of infiltrating lymphocytes to those achieved using four times the cytokine dosage. The combined therapy also resulted in lower levels of immunosuppressive molecules and higher levels of activated T-cells in the tumor microenvironment than immunotherapy alone. In conclusion, this study describes a new antitumor mechanism of CRT that involves the up-regulation of tumor endothelial adhesion molecules and the enhanced infiltration of tumor-specific lymphocytes. Thus, CRT treatment can make tumor cells more vulnerable to immunotherapy and improve the therapeutic efficacy of immunotherapy.

Angiogenesis and immunity: a bidirectional link potentially relevant for the monitoring of antiangiogenic therapy and the development of novel therapeutic combination with immunotherapy

The immune system regulates angiogenesis in cancer with both pro- and antiangiogenic activities. The induction of angiogenesis is mediated by tumor-associated macrophages and myeloid-derived suppressor cells (MDSC) which produce proinflammatory cytokines, endothelial growth factors (VEGF, bFGF…), and protease (MMP9) implicated in neoangiogenesis. Some cytokines (IL-6, IL-17…) activated Stat3 which also led to the production of VEGF and bFGF. In contrast, other cytokines (IFN, IL-12, IL-21, and IL-27) display an antiangiogenic activity. Recently, it has been shown that some antiangiogenic molecules alleviates immunosuppression associated with cancer by decreasing immunosuppressive cells (MDSC, regulatory T cells), immunosuppressive cytokines (IL-10, TGFβ), and inhibitory molecules on T cells (PD-1). Some of these broad effects may result from the ability of some antiangiogenic molecules, especially cytokines to inhibit the Stat3 transcription factor. The association often observed between angiogenesis and immunosuppression may be related to hypoxia which induces both neoangiogenesis via activation of HIF-1 and VEGF and favors the intratumor recruitment and differentiation of regulatory T cells and MDSC. Preliminary studies suggest that modulation of immune markers (intratumoral MDSC and IL-8, peripheral regulatory T cells…) may predict clinical response to antiangiogenic therapy. In preclinical models, a synergy has been observed between antiangiogenic molecules and immunotherapy which may be explained by an improvement of immune status in tumor-bearing mice after antiangiogenic therapy. In preclinical models, antiangiogenic molecules promoted intratumor trafficking of effector cells, enhance endogenous anti-tumor response, and synergyzed with immunotherapy protocols to cure established murine tumors. All these results warrant the development of clinical trials combining antiangiogenic drugs and immunotherapy.

The numbers of FoxP3+ lymphocytes in sentinel lymph nodes of breast cancer patients correlate with primary tumor size but not nodal status

Regulatory T cells, lymphocytes marked by expression of the transcription factor Forkhead Box Protein P3 (FoxP3), inhibit the activation of tumor-specific T cells in tumor-draining lymph nodes. Immunohistochemical analyses of sentinel lymph nodes (SLNs) from 104 breast cancer patients showed a significant association (p = .0028, Pearson correlation) between the number of FoxP3+ cells and the size of primary breast invasive ductal carcinoma. In contrast, there was no correlation between the number of FoxP3+ cells and the presence of SLN metastases, or other clinicopathological parameters. These results suggest the presence of an immune suppressive environment in SLNs of larger tumors.

Angiogenesis and the tumor vasculature as antitumor immune modulators: the role of vascular endothelial growth factor and endothelin

Cancer immunotherapies have yielded promising results in recent years, but new approaches must be utilized if more patients are to experience the benefits of these therapies. Angiogenesis and the tumor endothelium confer unique immune privilege to a growing tumor, with significant effects on diverse immunological processes such as hematopoietic cell maturation, antigen presentation, effector T cell differentiation, cytokine production, adhesion, and T cell homing and extravasation. Here, we review the role of angiogenesis and the tumor endothelium on regulation of the antitumor immune response. We place particular emphasis on the role of vascular endothelial growth factor (VEGF) in the suppression of numerous immunological processes that control tumor progression. Further, we describe the unique crosstalk between the VEGF and endothelin systems, and how their interactions may shape the antitumor immune response. These insights establish new targets for combinatorial approaches to modify existing cancer immunotherapies.

The immunosuppressive side of PDT

Photodynamic therapy (PDT) is a promising novel therapeutic procedure for the management of a variety of solid tumors and many non-malignant diseases. PDT has been described as having a significant effect on the immune system, which may be either immunostimulatory or, in some circumstances, immunosuppressive. The immunosuppressive effects of PDT have nearly all been concerned with the suppression of the contact hypersensitivity reaction in mice. Here, we review the immunosuppressive aspects of PDT treatment and discuss some additional mechanisms that may be involved.

Ganoderma lucidum polysaccharides antagonize the suppression on lymphocytes induced by culture supernatants of B16F10 melanoma cells

Objectives

Tumour cells produce factors such as interleukin 10 (IL-10), transforming growth factor β1 (TGF-β1) and vascular endothelial growth factor (VEGF) that suppress the function of immune cells or induce apoptosis of immune cells. One of the most important goals of tumour immunotherapy is to antagonize this suppression on immune cells. Ganoderma lucidum polysaccharides (Gl-PS) may have this potential. The purpose of this study was to determine the antagonistic effects of Gl-PS on the suppression induced by B16F10 melanoma cell culture supernatant (B16F10-CS) on lymphocytes.

Methods

Gl-PS was used on lymphocytes incubated with B16F10-CS. Enzyme-linked immunosorbent assay was used to determine the levels of IL-10, TGF-β1 and VEGF in B16F10-CS. The MTT assay was used to determine the proliferation of lymphocytes. Immunocytochemistry and Western blot assay were used to determine perforin and granzyme B production in lymphocytes.

Key findings

There were elevated levels of IL-10, TGF-β1 and VEGF in B16F10-CS. The lymphocyte proliferation, and perforin and granzyme B production in lymphocytes after induction with phytohemagglutinin, as well as lymphocyte proliferation in the mixed lymphocyte reaction, were suppressed by B16F10-CS. This suppression was fully or partially antagonized by Gl-PS.

Conclusions

B16F10-CS suppressed lymphocyte proliferation and perforin and granzyme B production in lymphocytes after induction with phytohemagglutinin, as well as lymphocyte proliferation in the mixed lymphocyte reaction. This suppression may be associated with elevated levels of immunosuppressive IL-10, TGF-β1 and VEGF in B16F10-CS. Gl-PS had antagonistic effects on the immunosuppression induced by B16F10-CS, suggesting the potential for Gl-PS in cancer immunotherapy.

Endothelial cell biology: role in the inflammatory response

Human endothelial cells are multifunctional cells that line blood vessels and are capable of secreting a variety of biologically active mediators. They normally maintain vascular hemostasis and prevent thrombotic complications. When affected by infection, stress, hypertension, dyslipidemia, or high homocysteine levels, endothelial cells undergo changes resulting in "dysfunction," characterized typically by decreased endothelial expression of nitric oxide, enhanced expression of cell adhesion molecules, and associated increased binding of circulating leukocytes to these cells. There is accompanying cytokine and chemokine elaboration, resulting in cellular recruitment and the orchestration of an acute inflammatory response that can culminate in chronic inflammation if reparative mechanisms are not operative. This review will address the basic biology of endothelial cells; the expression and regulation of endothelial-derived cytokines, chemokines, and growth factors; the transcriptional regulation of these genes in endothelial cells; and the role played by these fascinating cells in human disease.

Lymphocyte subpopulation and dendritic cell phenotyping during antineoplastic therapy in human solid tumors

Patients with cancer show variable levels of immunosuppression at the time of the presentation, and cytotoxic antineoplastic therapy is the primary contributor to the clinical immunodeficiency often observed during the course of the disease. In both hematological and solid tumors, this phenomenon is primarily related to the T-cell depletion associated with inhibition of dendritic cell ability to induce both primary and secondary T- and B-cell responses. Complete restoration of immunocompetence following antineoplastic therapy implicates the progressive recovery of various cell subpopulations, and it is a complex process that also depends on the type, the dose, the scheduling, and the associations of the employed drugs. In the era of target therapies, several antiangiogenic drugs are increasingly used in combination with standard chemotherapy in the treatment of advanced solid tumors. Their clinical efficacy has been recently related not only to the specific antiangiogenic properties but also to an indirect hypothetical effect on the host immune system. In the present work, we have reviewed the most recent information regarding (1) the capacity of standard antineoplastic therapy to induce and maintain an immunodeficiency in patients with solid tumors and (2) the influence of the antiangiogenic treatment in association with standard chemotherapy on lymphocyte and dendritic cell subsets and the possible resulting additional antitumor mechanism.

Expression of RNA interference triggers from an oncolytic herpes simplex virus results in specific silencing in tumour cells in vitro and tumours in vivo

Background

Delivery of small interfering RNA (siRNA) to tumours remains a major obstacle for the development of RNA interference (RNAi)-based therapeutics. Following the promising pre-clinical and clinical results with the oncolytic herpes simplex virus (HSV) OncoVEX^GM-CSF, we aimed to express RNAi triggers from oncolytic HSV, which although has the potential to improve treatment by silencing tumour-related genes, was not considered possible due to the highly oncolytic properties of HSV.

Methods

To evaluate RNAi-mediated silencing from an oncolytic HSV backbone, we developed novel replicating HSV vectors expressing short-hairpin RNA (shRNA) or artificial microRNA (miRNA) against the reporter genes green fluorescent protein (eGFP) and β-galactosidase (lacZ). These vectors were tested in non-tumour cell lines in vitro and tumour cells that are moderately susceptible to HSV infection both in vitro and in mice xenografts in vivo. Silencing was assessed at the protein level by fluorescent microscopy, x-gal staining, enzyme activity assay, and western blotting.

Results

Our results demonstrate that it is possible to express shRNA and artificial miRNA from an oncolytic HSV backbone, which had not been previously investigated. Furthermore, oncolytic HSV-mediated delivery of RNAi triggers resulted in effective and specific silencing of targeted genes in tumour cells in vitro and tumours in vivo, with the viruses expressing artificial miRNA being comprehensibly more effective.

Conclusions

This preliminary data provide the first demonstration of oncolytic HSV-mediated expression of shRNA or artificial miRNA and silencing of targeted genes in tumour cells in vitro and in vivo. The vectors developed in this study are being adapted to silence tumour-related genes in an ongoing study that aims to improve the effectiveness of oncolytic HSV treatment in tumours that are moderately susceptible to HSV infection and thus, potentially improve response rates seen in human clinical trials.

Combining antiangiogenic therapy with immunotherapy exerts better therapeutical effects on large tumors in a woodchuck hepatoma model

Cytokine and antiangiogenic gene therapies have proved effective in implanted hepatocellular carcinoma (HCC) models in which small tumor burdens were established in small rodents. These models, however, may not reflect human HCCs, which are frequently detected at a stage when tumors are large and multifocal. In addition, HCC in patients is often associated with viral hepatitis. To investigate the effectiveness of a mixture type of gene therapy strategy on large tumor burdens, we used the woodchuck model in which woodchuck hepatitis virus-induced HCCs are large and multifocal, simulating the conditions in humans. Adenoviruses encoding antiangiogenic factors (pigment epithelium-derived factor and endostatin) or cytokines (GM-CSF and IL-12) were delivered via the hepatic artery separately or in combination into woodchuck livers bearing HCCs. Our results showed that the mixture type of strategy, which contained two cytokines and two antiangiogenic factors, had better antitumor effects on large tumors as compared with monotherapy either with antiangiogenic or cytokine genes. The immunotherapy recruited significant levels of CD3(+) T cells that infiltrated the tumors, whereas the antiangiogenesis-based therapy significantly reduced tumor vasculature. The mixture type of gene therapy achieved both effects. In addition, it induced high levels of natural killer cells and apoptotic cells and reduced the levels of immunosuppressive effectors in the tumor regions. Hence, antiangiogenic therapy may provide the advantage of reducing immune tolerance in large tumors, making them more vulnerable to the immune reactions. Our study implies that in the future, the combination therapy may prove effective for the treatment of patients with advanced HCC.

Tumor microenvironment modifications induced by soluble VEGF receptor expression in a rat liver metastasis model

Vascular endothelial growth factor is a potent pro-angiogenic growth factor which is also known to alter tumor microenvironment by inhibiting dendritic cell differentiation and promoting accumulation of myeloid-derived suppressor cells. In the present study, we analyzed the modifications induced by intratumoral expression of sFLT-1, a soluble VEGF receptor, in a rat metastatic colon carcinoma model. We generated colon cancer cell lines stably expressing sFLT-1 or a mock construct. Human umbilical vein endothelial cells cultured with conditioned medium from sFLT-1-expressing tumor cells exhibit a significantly decreased survival, demonstrating the functionality of the secreted sFLT-1. Invivo, sFLT-1 expression induced a 30% decrease in microvessel density in 15-day old experimental liver metastasis from colon carcinoma. Tumor growth was inhibited by 63% and 52% in left and right liver lobes respectively within 25days. In these tumors, sFLT-1 expression was associated with a decreased myeloid cell infiltration and a modification in the expression of several cytokines/chemokines. Altogether, these results suggest that VEGF trapping by sFLT-1 intratumoral expression results in reduced vascularization, tumor growth inhibition and modification of immune tumor microenvironment.

Future prospects and challenges of antiangiogenic cancer gene therapy

In 1971 Judah Folkman proposed the concept of antiangiogenesis as a therapeutic target for cancer. More than 30 years later, concept became reality with the approval of the antivascular endothelial growth factor (VEGF) monoclonal antibody bevacizumab as a first-line treatment for metastatic colorectal cancer. Monoclonal antibodies and small molecular drugs are the most widely applied methods for inhibition of angiogenesis. The efficacy of these antiangiogenic modalities has been proven, in both preclinical and clinical settings. Although angiogenesis plays a major role in wound healing, hypoxia, and in the female reproductive cycle, inhibition of angiogenesis seems to be a relatively safe therapeutic option against cancers, and has therefore become a logical arena for a wide range of experimentation. The twentieth century has shown the boom of gene therapy and thus it has been applied also in the antiangiogenic setting. This review summarizes methods to induce antiangiogenic responses with gene therapy and discusses the obstacles and future prospects of antiangiogenic cancer gene therapy.

Antiangiogenic agents can increase lymphocyte infiltration into tumor and enhance the effectiveness of adoptive immunotherapy of cancer

Adoptive cell transfer (ACT)-based immunotherapies can mediate objective cancer regression in animal models and in up to 70% of patients with metastatic melanoma; however, it remains unclear whether the tumor vasculature impedes the egress of tumor-specific T cells, thus hindering this immunotherapy. Disruption of the proangiogenic interaction of vascular endothelial growth factor (VEGF) with its receptor (VEGFR-2) has been reported to "normalize" tumor vasculature, enhancing the efficacy of chemotherapeutic agents by increasing their delivery to the tumor intersitium. We thus sought to determine whether disrupting VEGF/VEGFR-2 signaling could enhance the effectiveness of ACT in a murine cancer model. The administration of an antibody against mouse VEGF synergized with ACT to enhance inhibition of established, vascularized, B16 melanoma (P = 0.009) and improve survival (P = 0.003). Additive effects of an antibody against VEGFR-2 in conjunction with ACT were seen in this model (P = 0.013). Anti-VEGF, but not anti-VEGFR-2, antibody significantly increased infiltration of transferred cells into the tumor. Thus, normalization of tumor vasculature through disruption of the VEGF/VEGFR-2 axis can increase extravasation of adoptively transferred T cells into the tumor and improve ACT-based immunotherapy. These studies provide a rationale for the exploration of combining antiangiogenic agents with ACT for the treatment of patients with cancer.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

AACR centennial series: the biology of cancer metastasis: historical perspective

Metastasis resistant to therapy is the major cause of death from cancer. Despite almost 200 years of study, the process of tumor metastasis remains controversial. Stephen Paget initially identified the role of host-tumor interactions on the basis of a review of autopsy records. His "seed and soil" hypothesis was substantiated a century later with experimental studies, and numerous reports have confirmed these seminal observations. An improved understanding of the metastatic process and the attributes of the cells selected by this process is critical for the treatment of patients with systemic disease. In many patients, metastasis has occurred by the time of diagnosis, so metastasis prevention may not be relevant. Treating systemic disease and identifying patients with early disease should be our goal. Revitalized research in the past three decades has focused on new discoveries in the biology of metastasis. Even though our understanding of molecular events that regulate metastasis has improved, the contributions and timing of molecular lesion(s) involved in metastasis pathogenesis remain unclear. Review of the history of pioneering observations and discussion of current controversies should increase understanding of the complex and multifactorial interactions between the host and selected tumor cells that contribute to fatal metastasis and should lead to the design of successful therapy.

Targeting inhibitory pathways in cancer immunotherapy

The clinical success of adaptive transfer of in vitro expanded antigen-specific CD8(+) T cells isolated from patients' tumors has demonstrated that effector cells of the adaptive immune system can effectively eliminate even large tumor masses. Nevertheless, cancer vaccines that aim to expand such CD8(+) T cells in situ have had remarkably little success in spite of numerous attempts. Recent advances in basic immunology have revealed layers of complexity controlling activation and maintenance of adaptive immune responses that are tightly controlled by immunoinhibitory pathways to avoid horror autotoxicus. During tumor progression the activities of negative pathways increase and together with cancer immune evasion tactics presumably prevent induction of an efficacious immune response by cancer vaccines that solely provide more antigen to an already suppressed system. Cancer vaccines may thus need to readjust the imbalance of the cancer patients' immune system by inhibiting immunoinhibitors; such regimens have shown preclinical efficacy and are now entering clinical trials hopefully ending the Kafkaesque futility of cancer vaccines.

Enhanced CD8 T cell cross-presentation by macrophages with targeted disruption of STAT3

CD8 T cell tolerance, once thought to be largely a result of clonal deletion, is now appreciated to be much more complex, additionally involving multiple permutations of partial loss of effector function in residual clonal populations. This is especially important in the context of tumor immunity, in which persistent tolerized cytotoxic CD8 T cells (CTL), if reactivated, could potentially mount a protective response. Previously we have shown that antigen-presenting cells (APCs) with a targeted disruption of STAT3 break tolerance in CD4 T cells. Here we evaluate the STAT3-defective APC in terms of its ability to induce a productive CTL response. Our data demonstrate that macrophages derived from conditional STAT3 knockout mice are superior to wild-type macrophages in terms of their ability to prime cognate CTL responses, and to cross-present tumor-derived antigen to CTLs in vitro. CTLs cultured with STAT3-deficient APCs demonstrated a stronger proliferative response and produced increased amounts of IFN-gamma and TNF-alpha, all of which have been shown to be diminished in tumor-tolerized CD8 T cells. Targeting STAT3 signaling represents therefore an enticing strategy to augment CTL responses in the tumor-bearing host.

The low expression of CD80 correlated with the vascular endothelial growth factor in esophageal cancer tissue

AIMS

To analyze the mRNA and protein expression of CD80 and vascular endothelial growth factor (VEGF) in esophageal cancer (EC) tissue, investigate the causes of esophageal cancer cell escape from immune surveillance.

METHODS

We detected the CD80 and VEGF mRNA with reverse transcription polymerase chain reaction (RT-PCR), CD80 protein with flow cytometry, VEGF protein with immunohistochemistry in the cancer tissues in 118 EC patients, and the normal esophageal tissue as controls.

RESULTS

The expression of CD80 mRNA and protein in cancer tissues were lower than that in the controls (p<0.01, respectively), The CD80 protein expression in poor differentiation was lower than that in the well and moderate (P<0.01), in the patients with lymph node metastasis lower than that with no metastasis (P=0.01), in stage IIIA patients lower than that in stages I and II patients (P=0.04); the VEGF mRNA and protein expression were just right opposite. The mean survival time in the CD80 positive group was significantly longer than that in the negative (p=0.041); while in VEGF positive group was lower than that in the negative (p=0.046). The CD80 expression of mRNA and protein were correlated negatively with VEGF in the cancer tissues (r=-0.82, -0.87, respectively).

CONCLUSION

It is suggested that CD80 was impaired in the EC tissues and correlated with the clinicopathological characteristics and prognosis, which indicated the dysfunction of immune system and enhancing the progression of EC. The low expression of CD80 correlated with the overexpression of VEGF.

Synergistic effect and VEGF/HSP70-hom haplotype analysis: relationship to prostate cancer risk and clinical outcome

Prostate cancer (PCa) is a complex disorder resulting from the combined effects of multiple environmental and genetic factors. Our previous single-locus analysis showed that VEGF and HSP70-hom polymorphisms were significantly associated with PCa susceptibility and prognosis. Both genes encoding these proteins were located on chromosome 6p21, and combining the neighboring single nucleotide polymorphisms (SNPs) into haplotypes may increase the association with the disease. Three tagging polymorphisms, the HSP70-hom 2437 T/C, the VEGF-1154 G/A, and the VEGF-634 G/C SNPs were genotyped in 101 cases and 80 controls. For the combined analysis of VEGF and HSP70-hom, we found a positive gradient in the odds ratios (ORs) related to the number of high-risk genotypes with a 3.53-fold increase of prostate carcinoma risk (OR = 3.53; p = 0.015). Furthermore, the TAG and CAG haplotypes at positions HSP70-hom, VEGF -1154 and VEGF -634 exhibited a two-fold (OR = 0.46; p = 0.014) and a seven-fold (OR = 0.14; p = 0.00005) reduction in PCa risk, respectively. Regarding PCa prognosis, the TAG haplotype had a negative association with the aggressive phenotype as defined by the histopathological grade (OR = 0.28; p = 0.006). Our findings confirm the role of at-risk haplotype across the HSP70-hom/VEGF gene cluster in determining susceptibility to PCa.

Hypoxic tumors and their effect on immune cells and cancer therapy

The abnormal decrease or the lack of oxygen supply to cells and tissues is called hypoxia. This condition is commonly seen in various diseases such as rheumatoid arthritis and atherosclerosis, also in solid cancers. Pre-clinical and clinical studies have shown that hypoxic cancers are extremely aggressive, resistant to standard therapies (chemotherapy and radiotherapy), and thus very difficult to eradicate. Hypoxia affects both the tumor and the immune cells via various pathways. This review summarizes the most common effects of hypoxia on immune cells that play a key role in the anti-tumor response, the limitation of current therapies, and the potential solutions that were developed for hypoxic malignancies.

Generation of stable Th1/CTL-, Th2-, and Th17-inducing human dendritic cells

Dendritic cells (DC) are the most potent inducers and regulators of immune responses, responsible for communication within immune system. The ability of DC to act both as the inducers of immune responses and as regulatory/suppressive cells led to the interest in their immunotherapeutic use in different disease types, ranging from cancer to autoimmunity, and as a tool to prevent the rejection of transplanted tissues and organs. Over the last years, several groups including ours have demonstrated the feasibility of obtaining monocyte-derived DC with different functions, by modulating the conditions and the duration of DC maturation. The current chapter provides a detailed protocol of generating type-1-, type-2-, and type-17-polarized DC for testing the cytokine-producing abilities of these cells and their effectiveness in inducing Th1, Th2, and Th17 responses of CD4(+) T cells and CTL responses of naïve and memory CD8(+) T cells.

Cancer associated fibroblasts promote tumor growth and metastasis by modulating the tumor immune microenvironment in a 4T1 murine breast cancer model

Background

Local inflammation associated with solid tumors commonly results from factors released by tumor cells and the tumor stroma, and promotes tumor progression. Cancer associated fibroblasts comprise a majority of the cells found in tumor stroma and are appealing targets for cancer therapy. Here, our aim was to determine the efficacy of targeting cancer associated fibroblasts for the treatment of metastatic breast cancer.

Methodology/Principal Findings

We demonstrate that cancer associated fibroblasts are key modulators of immune polarization in the tumor microenvironment of a 4T1 murine model of metastatic breast cancer. Elimination of cancer associated fibroblasts in vivo by a DNA vaccine targeted to fibroblast activation protein results in a shift of the immune microenvironment from a Th2 to Th1 polarization. This shift is characterized by increased protein expression of IL-2 and IL-7, suppressed recruitment of tumor-associated macrophages, myeloid derived suppressor cells, T regulatory cells, and decreased tumor angiogenesis and lymphangiogenesis. Additionally, the vaccine improved anti-metastatic effects of doxorubicin chemotherapy and enhanced suppression of IL-6 and IL-4 protein expression while increasing recruitment of dendritic cells and CD8⁺ T cells. Treatment with the combination therapy also reduced tumor-associated Vegf, Pdgfc, and GM-CSF mRNA and protein expression.

Conclusions/Significance

Our findings demonstrate that cancer associated fibroblasts promote tumor growth and metastasis through their role as key modulators of immune polarization in the tumor microenvironment and are valid targets for therapy of metastatic breast cancer.

Metastatic tumour cells favour the generation of a tolerogenic milieu in tumour draining lymph node in patients with early cervical cancer

OBJECTIVE

We compared the immune system state in metastatic tumour draining lymph nodes (mTDLN) and metastasis free TDLN (mfTDLN) in 53 early stage cervical cancer patients to assess whether the presence of metastatic tumour cells worsen the balance between an efficacious anti-tumour and a tolerogenic microenvironment.

METHODS

The immune system state was measured by immunophenotypic and functional assessment of suppressor and effector immune cell subsets.

RESULTS

Compared to mfTDLN, mTDLN were significantly enriched in CD4(+)Foxp3(+) regulatory T cells (Treg), which, in addition, exhibited an activated phenotype (HLA-DR(+) and CD69(+)). Treg in mTDLN were also significantly enriched in neuropilin-1 (Nrp1) expressing cells, a subset particularly potent in dampening T cell responses. mTDLN tended to be enriched in a population of CD8(+)Foxp3(+)T cells (operationally defined as CD8(+)Treg) that showed a suppressor potency similar to Treg under the same experimental conditions. Plasmacytoid dendritic cells (pDC) and myeloid DC (mDC) generally show distinct roles in inducing T cell tolerance and activation, respectively. In line with the excess of suppressor T cells, the ratio pDC to mDC was significantly increased in mTDLN. Immunohistochemical testing showed that metastatic tumour cells produced the vascular endothelial growth factor, a natural ligand for Nrp1 expressed on the cell surface of Nrp1(+)Treg and pDC, and therefore a potential mediator by which tumour cells foster immune privilege in mTDLN. Consistent with the overall tolerogenic profile, mTDLN showed a significant Tc2 polarisation and tended to contain lower numbers of CD45RA(+)CD27(-) effector memory CD8(+)T cells.

CONCLUSIONS

The increased recruitment of suppressor type cells concomitant with the scarcity of cytotoxic type cells suggests that in mTDLN the presence of tumour cells could tip the balance against anti-tumour immune response facilitating the survival of metastatic tumour cells and possibly contributing to systemic tolerance.

GM-CSF Gene-Modifed Cancer Cell Immunotherapies: Of Mice and Men

GVAX cancer immunotherapies are composed of whole tumor cells genetically modified to secrete the immune stimulatory cytokine, granulocyte-macrophage colony-stimulating factor (GM-CSF), and then irradiated to prevent further cell division. Both autologous (patient specific) and allogeneic (non-patient specific) GVAX platforms have been evaluated either as single agents or in combination with other immunomodulatory strategies. Many early-phase clinical trials have now been completed. Results have consistently demonstrated a favorable safety profile manifested primarily by injection site reactions and flu-like symptoms. Consistent evidence of immune activation and clinical activity, including radiologic tumor regressions, has been seen across multiple cancer indications in both early- and late-stage disease. Phase 3 trials evaluating an allogeneic GVAX immunotherapy product in prostate cancer are under way.

Circulating vascular endothelial growth factor six months after primary surgery as a prognostic marker in patients with colorectal cancer

High preoperative circulating vascular endothelial growth factor (VEGF) is predictive of poor prognosis in patients with colorectal cancer (CRC). However, postoperative circulating VEGF has not yet been evaluated as a prognostic marker in CRC patients. In 318 consecutive patients who had undergone curative resection of primary CRC, the prognostic value of VEGF concentrations in plasma and serum obtained 6 months postoperatively was analysed and the results compared with the prognostic value of postoperative carcinoembryonic antigen (CEA) concentrations in matched serum samples. In univariate analyses, high serum and plasma VEGF ( > 533 pg/ml and > 112 pg/ml, respectively) had no significant (p = 0.17 and p = 0.13, respectively) impact on overall survival. On the contrary, high serum CEA ( > 5 ng/ ml) was significantly (p < 0.0001) correlated to a poor prognosis. Finally, in multivariate analyses, the combination of high serum CEA and high serum VEGF was significantly (hazard ratio 3.0, p = 0.02) associated with poor survival compared to high serum CEA and low serum VEGF. It is concluded that 6 months postoperatively serum CEA is a better prognostic marker than corresponding serum and plasma VEGF. However, high serum VEGF within high serum CEA was an even better predictor of overall survival than high serum CEA alone.

Ovarian Carcinoma Cells Effectively Inhibit Differentiation and Maturation of Dendritic Cells Derived from Hematopoietic Progenitor Cells In Vitro

Loco-regional dissemination of ovarian carcinoma is associated with immunosuppression of the peritoneal cavity. One marked characteristic of the peritoneal immunity in this disease is the defective function of dendritic cells (DCs). In this study, the affect of ovarian carcinoma cells on DCs derived from hematopoetic progenitor cells was observed. The study demonstrated that the expansion, phenotype, and function of DCs generated from CD34+ precursors were significantly altered by the supernatant secreted by ovarian carcinoma cells, and this effect could be partly explained by tumoral overproduction of Vascular Endothelial Growth Factor (VEGF). The results indicated that a role of ovarian carcinoma cells in the differentiation and function of DCs could be associated with the immunosuppression and development of ovarian carcinoma.

Myeloid dendritic cells from human cutaneous squamous cell carcinoma are poor stimulators of T-cell proliferation

To determine the phenotype and function of myeloid dendritic cells (DCs) from human cutaneous squamous-cell carcinoma (SCC), we studied their surface marker expression and allo-stimulatory potential ex vivo. There were abundant CD11c(+) myeloid DCs, as well as TNF and inducible nitric oxide synthase (iNOS)-producing DCs, in and around SCC tumor nests. Although myeloid DCs from SCC, adjacent non-tumor-bearing skin, and normal skin, were phenotypically similar by flow cytometry, and there was a pronounced genomic signature of mature DCs in SCC, they showed different T-cell stimulatory potential in an allogeneic mixed leukocyte reaction. Myeloid DCs from SCC were less potent stimulators of allogeneic T-cell proliferation than DCs from non-tumor-bearing skin. Culture with a DC-maturing cytokine cocktail (IL-1beta, IL-6, TNF-alpha, and PGE(2)) enhanced stimulatory potential in DCs from non-tumor-bearing skin, whereas SCC-associated DCs remained poor stimulators of T-cell proliferation. The microenvironment associated with SCC showed expression of TGF-beta, IL-10, and VEGF-A, factors capable of suppressing the DC function. These findings indicate that CD11c(+)/HLA-DR(hi) DCs from SCC are mature, but are not potent stimulators of T-cell proliferation compared with phenotypically similar DCs isolated from non-tumor-bearing skin. Identification of mechanisms responsible for suppression of tumor-associated DCs may provide insight into the evasion of immunosurveillance by SCC.

Arginine regulation by myeloid derived suppressor cells and tolerance in cancer: mechanisms and therapeutic perspectives

Patients with cancer have an impaired T-cell response that can decrease the potential therapeutic benefit of cancer vaccines and other forms of immunotherapy. L-arginine (L-Arg) is a conditionally essential amino acid that is fundamental for the function of T lymphocytes. Recent findings in tumor-bearing mice and cancer patients indicate that increased metabolism of L-Arg by myeloid derived suppressor cells (MDSCs) producing arginase I inhibits T-lymphocyte responses. Here we discuss some of the most recent concepts how MDSC expressing arginase I may regulate T-cell function in cancer and other chronic inflammatory diseases and suggest possible therapeutic interventions to overcome this inhibitory effect.