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1.  CCL2 Blockade Augments Cancer Immunotherapy 
Cancer research  2009;70(1):109.
Since an immuno-inhibitory environment exists within tumors, successful vaccines will likely require additional approaches to alter the tumor microenvironment. Monocyte chemoattractant proteins (such as CCL2) are produced by many tumors and have both direct and indirect immuno-inhibitory effects. We hypothesized that CCL2 blockade would reduce immunosuppression and augment vaccine immunotherapy. Anti-murine-CCL2/CCL12 monoclonal antibodies were administered in three immunotherapy models: one aimed at the HPV-E7 antigen expressed by a non-small cell lung cancer line, one targeted to mesothelin expressed by a mesothelioma cell line, and one using an adenovirus expressing Interferon-α to treat a non-immunogenic, non-small cell lung cancer line. We evaluated the effect of the combination treatment on tumor growth and assessed the mechanism of these changes by evaluating cytotoxic T cells, immunosuppressive cells, and the tumor microenvironment. Administration of anti-CCL2/CCL12 antibodies along with the vaccines markedly augmented efficacy with enhanced reduction in tumor volume and cures of approximately half of the tumors. The combined treatment generated more total intra-tumoral CD8+ T-cells that were more activated and more anti-tumor antigen specific, as measured by tetramer evaluation. Another important potential mechanism was reduction in intratumoral T-regulatory (T-reg) cells. CCL2 appears to be a key proximal cytokine mediating immunosuppression in tumors. Its blockade augments CD8+ T cell immune response to tumors elicited by vaccines via multifactorial mechanisms. These observations suggest that combining CCL2 neutralization with vaccines should be considered in future immunotherapy trials.
PMCID: PMC2821565  PMID: 20028856
CCL2; Cancer immunotherapy; Lung Cancer; Mesothelioma; T-lymphocytes
2.  Immuno-Therapy with Anti-CTLA4 Antibodies in Tolerized and Non-Tolerized Mouse Tumor Models 
PLoS ONE  2011;6(7):e22303.
Monoclonal antibodies specific for cytotoxic T lymphocyte-associated antigen 4 (anti-CTLA4) are a novel form of cancer immunotherapy. While preclinical studies in mouse tumor models have shown anti-tumor efficacy of anti-CTLA4 injection or expression, anti-CTLA4 treatment in patients with advanced cancers had disappointing therapeutic benefit. These discrepancies have to be addressed in more adequate pre-clinical models. We employed two tumor models. The first model is based on C57Bl/6 mice and syngeneic TC-1 tumors expressing HPV16 E6/E7. In this model, the HPV antigens are neo-antigens, against which no central tolerance exists. The second model involves mice transgenic for the proto-oncogen neu and syngeneic mouse mammary carcinoma (MMC) cells. In this model tolerance to Neu involves both central and peripheral mechanisms. Anti-CTLA4 delivery as a protein or expression from gene-modified tumor cells were therapeutically efficacious in the non-tolerized TC-1 tumor model, but had no effect in the MMC-model. We also used the two tumor models to test an immuno-gene therapy approach for anti-CTLA4. Recently, we used an approach based on hematopoietic stem cells (HSC) to deliver the relaxin gene to tumors and showed that this approach facilitates pre-existing anti-tumor T-cells to control tumor growth in the MMC tumor model. However, unexpectedly, when used for anti-CTLA4 gene delivery in this study, the HSC-based approach was therapeutically detrimental in both the TC-1 and MMC models. Anti-CTLA4 expression in these models resulted in an increase in the number of intratumoral CD1d+ NKT cells and in the expression of TGF-β1. At the same time, levels of pro-inflammatory cytokines and chemokines, which potentially can support anti-tumor T-cell responses, were lower in tumors of mice that received anti-CTLA4-HSC therapy. The differences in outcomes between the tolerized and non-tolerized models also provide a potential explanation for the low efficacy of CTLA4 blockage approaches in cancer immunotherapy trials.
PMCID: PMC3136517  PMID: 21779410
3.  Synergistic enhancement of CD8+ T cell-mediated tumor vaccine efficacy by an anti-TGF-β monoclonal antibody 
TGF-β is an immunosuppressive cytokine, having direct suppressive activity against conventional CD4+ and CD8+T cells and NK cells, thereby inhibiting tumor immunosurveillance. Here we investigated possible synergy between anti-TGF-β (1D11) and a peptide vaccine on induction of anti-tumor immunity, and the mechanisms accounting for synergistic efficacy.
Experimental Design
The effect of combination treatment with a peptide vaccine and anti-TGF-β was examined in a subcutaneous TC1 tumor model, as well as the mechanisms of protection induced by this treatment.
Anti-TGF-β significantly and synergistically improved vaccine efficacy as measured by reduction in primary tumor growth, although anti-TGF-β alone had no impact. The number of tumor antigen-specific CTL with high functional avidity as measured by IFN-γ production and lytic activity was significantly increased in vaccinated mice by TGF-β neutralization. Although TGF-β is known to play a critical role in CD4+Foxp3+ Treg cells, Treg depletion/suppression by an anti-CD25 mAb (PC61) prior to tumor challenge did not enhance vaccine efficacy, and adding anti-TGF-β did not affect Treg numbers in lymph nodes or tumors or their function. Also, TGF-β neutralization had no effect on IL-17-producing T cells, which are induced by TGF-β and IL-6. Absence of type II NKT cells, which induce myeloid cells to produce TGF-β was not sufficient to eliminate all sources of suppressive TGF-β. Finally, the synergistic protection induced by anti-TGF-β vaccine augmentation was mediated by CD8+ T cells since anti-CD8 treatment completely abrogated the effect.
These results suggest that TGF-β blockade may be useful for enhancing cancer vaccine efficacy.
PMCID: PMC2804258  PMID: 19861451
TGF-β; vaccine; CD8+ T cells
4.  Interleukin-7 Gene-Modified Dendritic Cells Reduce Pulmonary Tumor Burden in Spontaneous Murine Bronchoalveolar Cell Carcinoma 
Human gene therapy  2003;14(16):1511-1524.
The antitumor efficiency of dendritic cells transduced with an adenovirus vector expressing interleukin (IL)- 7 (DC-AdIL-7) was evaluated in a murine model of spontaneous bronchoalveolar cell carcinoma. These transgenic mice (CC-10 TAg), expressing the SV40 large T antigen under the Clara cell promoter, develop bilateral multifocal pulmonary adenocarcinomas and die at 4 months as a result of progressive pulmonary tumor burden. Injection of DC-AdIL-7 in the axillary lymph node region (ALNR) weekly for 3 weeks led to a marked reduction in tumor burden with extensive lymphocytic infiltration of the tumors and enhanced survival. The antitumor responses were accompanied by the enhanced elaboration of interferon (IFN)-γ and IL-12 as well as an increase in the antiangiogenic chemokines, IFN-γ–inducible protein 10 (IP-10/CXCL10) and monokine induced by IFN-γ (MIG/CXCL9). In contrast, production of the immunosuppressive mediators IL-10, transforming growth factor (TGF)-β, prostaglandin E2 (PGE2), and the proangiogenic modulator vascular endothelial growth factor (VEGF) decreased in response to DC-AdIL-7 treatment. Significant reduction in tumor burden in a model in which tumors develop in an organ-specific manner provides a strong rationale for further evaluation of DC-AdIL-7 in regulation of tumor immunity and its use in lung cancer genetic immunotherapy.
In our previous studies, intratumoral administration of adenoviral interleukin (IL)-7–transduced dendritic cells (DC-AdIL- 7) resulted in specific systemic antitumor immune responses that led to complete tumor regression and long-term immunity. The intratumoral administration of gene-modified dendritic cells (DC) resulted in effective trafficking of transferred DCs to regional lymph nodes. To determine if direct administration of DC-AdIL-7 in the axillary lymph node region (ALNR) would mediate a significant response against pulmonary tumor, we tested the antitumor efficacy of DC-AdIL-7 in a spontaneous murine lung cancer model. In the CC-10 TAg mice, adenocarcinomas develop in an organ-specific manner and, compared to transplantable tumors, the pulmonary tumors in these mice more closely resemble human lung cancer. In this study we demonstrate that ALNR injection of DC-AdIL-7 mediates potent antitumor responses in vivo leading to a significant reduction in tumor burden.
PMCID: PMC1471881  PMID: 14577913
5.  Combined TLR2/4-Activated Dendritic/Tumor Cell Fusions Induce Augmented Cytotoxic T Lymphocytes 
PLoS ONE  2013;8(3):e59280.
Induction of antitumor immunity by dendritic cell (DC)-tumor fusion cells (DC/tumor) can be modulated by their activation status. In this study, to address optimal status of DC/tumor to induce efficient antigen-specific cytotoxic T lymphocytes (CTLs), we have created various types of DC/tumor: 1) un-activated DC/tumor; 2) penicillin-killed Streptococcus pyogenes (OK-432; TLR4 agonist)-activated DC/tumor; 3) protein-bound polysaccharides isolated from Coriolus versicolor (PSK; TLR2 agonist)-activated DC/tumor; and 4) Combined OK-432- and PSK-activated DC/tumor. Moreover, we assessed the effects of TGF-β1 derived from DC/tumor on the induction of MUC1-specific CTLs. Combined TLR2- and TLR4-activated DC/tumor overcame immune-suppressive effect of TGF-β1 in comparison to those single activated or un-activated DC/tumor as demonstrated by: 1) up-regulation of MHC class II and CD86 expression on DC/tumor; 2) increased fusion efficiency; 3) increased production of fusions derived IL-12p70; 4) activation of CD4+ and CD8+ T cells that produce high levels of IFN-γ; 5) augmented induction of CTL activity specific for MUC1; and 6) superior efficacy in inhibiting CD4+CD25+Foxp3+ T cell generation. However, DC/tumor-derived TGF-β1 reduced the efficacy of DC/tumor vaccine in vitro. Incorporating combined TLRs-activation and TGF-β1-blockade of DC/tumor may enhance the effectiveness of DC/tumor-based cancer vaccines and have the potential applicability to the field of adoptive immunotherapy.
PMCID: PMC3598755  PMID: 23555011
6.  HMGB1 Mediates Endogenous TLR2 Activation and Brain Tumor Regression 
PLoS Medicine  2009;6(1):e1000010.
Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor that carries a 5-y survival rate of 5%. Attempts at eliciting a clinically relevant anti-GBM immune response in brain tumor patients have met with limited success, which is due to brain immune privilege, tumor immune evasion, and a paucity of dendritic cells (DCs) within the central nervous system. Herein we uncovered a novel pathway for the activation of an effective anti-GBM immune response mediated by high-mobility-group box 1 (HMGB1), an alarmin protein released from dying tumor cells, which acts as an endogenous ligand for Toll-like receptor 2 (TLR2) signaling on bone marrow-derived GBM-infiltrating DCs.
Methods and Findings
Using a combined immunotherapy/conditional cytotoxic approach that utilizes adenoviral vectors (Ad) expressing Fms-like tyrosine kinase 3 ligand (Flt3L) and thymidine kinase (TK) delivered into the tumor mass, we demonstrated that CD4+ and CD8+ T cells were required for tumor regression and immunological memory. Increased numbers of bone marrow-derived, tumor-infiltrating myeloid DCs (mDCs) were observed in response to the therapy. Infiltration of mDCs into the GBM, clonal expansion of antitumor T cells, and induction of an effective anti-GBM immune response were TLR2 dependent. We then proceeded to identify the endogenous ligand responsible for TLR2 signaling on tumor-infiltrating mDCs. We demonstrated that HMGB1 was released from dying tumor cells, in response to Ad-TK (+ gancyclovir [GCV]) treatment. Increased levels of HMGB1 were also detected in the serum of tumor-bearing Ad-Flt3L/Ad-TK (+GCV)-treated mice. Specific activation of TLR2 signaling was induced by supernatants from Ad-TK (+GCV)-treated GBM cells; this activation was blocked by glycyrrhizin (a specific HMGB1 inhibitor) or with antibodies to HMGB1. HMGB1 was also released from melanoma, small cell lung carcinoma, and glioma cells treated with radiation or temozolomide. Administration of either glycyrrhizin or anti-HMGB1 immunoglobulins to tumor-bearing Ad-Flt3L and Ad-TK treated mice, abolished therapeutic efficacy, highlighting the critical role played by HMGB1-mediated TLR2 signaling to elicit tumor regression. Therapeutic efficacy of Ad-Flt3L and Ad-TK (+GCV) treatment was demonstrated in a second glioma model and in an intracranial melanoma model with concomitant increases in the levels of circulating HMGB1.
Our data provide evidence for the molecular and cellular mechanisms that support the rationale for the clinical implementation of antibrain cancer immunotherapies in combination with tumor killing approaches in order to elicit effective antitumor immune responses, and thus, will impact clinical neuro-oncology practice.
Maria Castro and colleagues use cell line and transgenic mouse approaches to study the mechanisms underlying the immune response to glioblastoma multiforme.
Editors' Summary
Every year, more than 175,000 people develop a primary brain tumor (a cancer that starts in the brain rather than spreading in from elsewhere). Like all cancers, brain tumors develop when a cell acquires genetic changes that allow it to grow uncontrollably and that change other aspects of its behavior, including the proteins it makes. There are many different types of cells in the brain and, as a result, there are many different types of brain tumors. However, one in five primary brain tumors is glioblastoma multiforme (GBM; also known as grade 4 astrocytoma), a particularly aggressive cancer. With GBM, the average time from diagnosis to death is one year and only one person in 20 survives for five years after a diagnosis of GBM. Symptoms of GBM include headaches, seizures, and changes in memory, mood, or mental capacity. Treatments for GBM, which include surgery, radiotherapy, and chemotherapy, do not “cure” the tumor but they can ease these symptoms.
Why Was This Study Done?
Better treatments for GBM are badly needed, and one avenue that is being explored is immunotherapy—a treatment in which the immune system is used to fight the cancer. Because many tumors make unusual proteins, the immune system can sometimes be encouraged to recognize tumor cells as foreign invaders and kill them. Unfortunately, attempts to induce a clinically useful anti-GBM immune response have been unsuccessful, partly because the brain contains very few dendritic cells, a type of immune system cell that kick-starts effective immune responses by presenting foreign proteins to other immune system cells. Another barrier to immunotherapy for GBM is immune evasion by the tumor. Many tumors develop ways to avoid the immune response as they grow. For example, they sometimes reduce the expression of proteins that the immune system might recognize as foreign. In this study, the researchers test a new combined treatment strategy for GBM in which dendritic cells are encouraged to enter the brain and tumor cells are killed to release proteins capable of stimulating an effective antitumor immune response.
What Did the Researchers Do and Find?
The researchers first established brain tumors in mice. Then, they injected harmless viruses carrying the genes for Fms-like tyrosine kinase 3 ligand (Ftl3L; a protein that attracts dendritic cells) and for thymidine kinase (TK; cells expressing TK are killed by a drug called gancyclovir) into the tumor. Expression of both Flt3L and TK (but not of either protein alone) plus gancyclovir treatment shrank the tumors and greatly improved the survival of the mice. The researchers show that their strategy increased the migration of dendritic cells into the tumor provided they expressed an immune system protein called Toll-like receptor 2 (TLR2). TLR2 expression on the dendritic cells was also needed for an effective anti-tumor immune response and for tumor regression. TLR2 normally activates dendritic cells by binding to specific proteins on invading pathogens, so what was TLR2 binding to in the mouse tumors? The researchers reveal that TLR2 was responding to high-mobility-group box 1 (HMGB1), a protein released by the dying tumor cells by showing that treatment of the tumor-bearing mice with the HMGB1 inhibitor glycyrrhizin blocked the therapeutic effect of Flt3L/TK expression. Finally, the researchers report that other tumor cell types release HMGB1 when they are killed and that the Flt3L/TK expression strategy can also kill other tumors growing in mouse brains.
What Do These Findings Mean?
Results obtained in mouse models of human diseases do not always lead to effective treatments for human patients. Nevertheless, the findings of this study provide new insights into how an effective immune response against brain tumors might be brought about. Most importantly, they show that an effective strategy might need to both attract dendritic cells into the brain tumor and to kill tumor cells, so they release proteins that can activate the dendritic cells. That is, the authors suggest it's important to combine immunotherapies with tumor-killing strategies to provide effective treatments for primary and metastatic brain tumors
Additional Information.
Please access these Web sites via the online version of this summary at
The US National Cancer Institute provides information about brain tumors for patients and health professionals and about the the immune system and how it can be harnessed to fight cancer (in English and Spanish)
Cancer Research UK provides information on all aspects of brain tumors for patients and their caregivers
MedlinePlus provides links to further information about brain cancer, (including some links to information in Spanish)
The American Brain Tumor Association provides brain tumor resources and information
The National Brain Tumor Society provides educational and support services regarding brain tumors
PMCID: PMC2621261  PMID: 19143470
7.  TGF-β Receptor Blockade Augments the Effectiveness of Adoptive T-Cell Therapy of Established Solid Cancers 
Adoptive cellular immunotherapy has promise as an approach to eradicate established tumors. However, a significant hurdle in the success of cellular immunotherapy involves recently identified mechanisms of immune suppression on cytotoxic T-cells at the effector phase.
Transforming growth factor-β (TGF-β) is one of the most important of these immunosuppressive factors because it affects both T-cell and macrophage functions. We thus hypothesized that systemic blockade of TGF-β signaling combined with adoptive T-cell transfer would enhance the effectiveness of the therapy.
Experimental Design
Flank tumors were generated in mice using the OVA-albumin (OA) expressing thymoma cell line, EG7. Splenocytes from transgenic OT-1 mice (whose CD8 T-cells recognize an immunodominant peptide in OA) were activated in vitro and adoptively transferred into mice bearing large tumors in the presence or absence of an orally available TGF-β receptor-I kinase blocker (SM16).
We observed markedly smaller tumors in the group receiving the combination of SM16 chow and adoptive transfer. Additional investigation revealed that TGF-β receptor blockade increased the persistence of adoptively transferred T-cells in the spleen and lymph nodes, increased numbers of adoptively transferred T-cells within tumors, increased activation of these infiltrating T-cells, and altered the tumor microenvironment with a significant increase in TNF-α and decrease in arginase mRNA expression
We found that systemic blockade of TGF-β receptor activity augmented the anti-tumor activity of adoptively transferred T-cells and may thus be a useful adjunct in future clinical trials.
PMCID: PMC2491721  PMID: 18559619
tumor immunology; immunosuppression; TGFβ; Cytotoxic T-cells; cytokines; adoptive transfer
8.  Regulation gene expression of miR200c and ZEB1 positively enhances effect of tumor vaccine B16F10/GPI-IL-21 on inhibition of melanoma growth and metastasis 
Genetically modified cells have been shown to be one of the most effective tumor vaccine strategies. However, in many cases, such as in melanoma, induction of a potent immune responses against the disease still remains a major challenge. Thus, novel strategies to reinforce tumor vaccine efficacy are needed. Using microRNA (miR) and Zinc-finger E-box binding homeobox (ZEB) have received much attention for potentially regulating tumor progression. To elicit a potent antitumor efficacy against melanoma, we used tumor vaccine in combination with miR200c overexpression or ZEB1 knockdown to assess the efficacy of treatment of murine melanoma.
B16F10 cell vaccine expressing interleukin 21 (IL-21) in the glycosylpho- sphatidylinositol (GPI)-anchored form (B16F10/GPI-IL-21) were developed. The vaccine was immunized into mice challenged by B16F10 cells or B16F10 cells stably transduced with lentiviral-miR200c (B16F10/miR200c) or transfected with the ZEB1-shRNA recombinant (B16F10/shZEB1) or the B16F10/GPI-IL-21 vaccine. The immune responses, tumorigenicity and lung metastasis in mice were evaluated, respectively.
The vaccination with B16F10/GPI-IL-21 markedly increased the serum cytokine levels of IFN-γ, TNF-α, IL-4 and decreased TGF-β level as well as augmented the cytotoxicity of splenocytes in immunized mice compared with control mice. In addition, the tumor vaccine B16F10/GPI-IL-21 significantly inhibited the tumor growth and reduced counts of lung metastases in mice challenged by B16F10/GPI-IL-21, B16F10/shZEB1 and B16F10/miR200c respectively compared with the control mice challenged by B16F10 cells. The efficacy mechanisms may involve in reinforcing immune responses, increasing expression of miR200c, E-cadherin and SMAD-7 and decreasing expression of TGF-β, ZEB1, Vimentin and N-cadherin in tumor tissues from the immunized mice.
These results indicate that the tumor vaccine B16F10/GPI-IL-21 in combination with miR200c overexpression or ZEB1 knockdown effectively inhibited melanoma growth and metastasis a murine model. Such a strategy may, therefore, be used for the clinical trials.
PMCID: PMC3995592  PMID: 24625224
Melanoma; Tumor vaccine; Interleukin −21; miR200c; Zinc-finger E-box binding homeobox 1
9.  Anti-PD-1 antibody significantly increases therapeutic efficacy of Listeria monocytogenes (Lm)-LLO immunotherapy 
One of the significant tumor immune escape mechanisms and substantial barrier for successful immunotherapy is tumor-mediated inhibition of immune response through cell-to-cell or receptor/ligand interactions. Programmed death receptor-1 (PD-1) interaction with its ligands, PD-L1 and PD-L2, is one of the important strategies that many tumors employ to escape immune surveillance. Upon PD-Ls binding to PD-1, T cell receptor (TCR) signaling is dampened, causing inhibition of proliferation, decreased cytokine production, anergy and/or apoptosis. Thus PD-Ls expression by tumor cells serves as a protective mechanism, leading to suppression of tumor-infiltrating lymphocytes in the tumor microenvironment. Lm-LLO immunotherapies have been shown to be therapeutically effective due to their ability to induce potent antigen-specific immune responses. However, it has been demonstrated that infection with Lm leads to up-regulation of PD-L1 on mouse immune cells that can inhibit effector T cells through PD-1/PD-L1 pathway.
Therapeutic and immune efficacy of Listeria-based vaccine (Lm-LLO-E7) in combination with anti-PD-1 antibody was tested in E7 antigen expressing TC-1 mouse tumor model. Tumor growth, survival, as well as peripheral and tumor-infiltrating immune cell profiles after immunotherapy were assessed.
Here we demonstrate that the combination of an Lm-LLO immunotherapy with anti-PD-1 antibody that blocks PD-1/PD-L1 interaction, significantly improves immune and therapeutic efficacy of treatment in TC-1 mouse tumor model. Importantly, we show that in addition to significant reduction of regulatory T cells (Treg) and myeloid-derived suppressor cells (MDSC) in both spleen and tumor microenvironment that are mediated solely by the Lm-LLO immunotherapy, the addition of anti-PD-1 antibody to the treatment results in significant increase of antigen-specific immune responses in periphery and CD8 T cell infiltration into the tumor. As a result, this combinational treatment leads to significant inhibition of tumor growth and prolonged survival/complete regression of tumors in treated animals.
We also demonstrate that in vitro infection with Lm results in significant upregulation of surface PD-L1 expression on human monocyte-derived dendritic cells suggesting the translational capacity of this finding.
Our findings demonstrate that combination of Lm-LLO-based vaccine with blocking of PD-1/PD-L1 interaction is a feasible approach with clinical translation potential that can lead to overall enhancement of the efficacy of anti-tumor immunotherapy.
PMCID: PMC4019896  PMID: 24829751
PD-1; Immunotherapy; Listeria-based vaccine; Combinational immunotherapy
10.  Intratumoral peptide injection enhances tumor cell antigenicity recognized by cytotoxic T lymphocytes: a potential option for improvement in antigen-specific cancer immunotherapy 
Cancer Immunology, Immunotherapy  2012;62(4):639-652.
Antigen-specific cancer immunotherapy is a promising strategy for improving cancer treatment. Recently, many tumor-associated antigens and their epitopes recognized by cytotoxic T lymphocytes (CTLs) have been identified. However, the density of endogenously presented antigen-derived peptides on tumor cells is generally sparse, resulting in the inability of antigen-specific CTLs to work effectively. We hypothesize that increasing the density of an antigen-derived peptide would enhance antigen-specific cancer immunotherapy. Here, we demonstrated that intratumoral peptide injection leads to additional peptide loading onto major histocompatibility complex class I molecules of tumor cells, enhancing tumor cell recognition by antigen-specific CTLs. In in vitro studies, human leukocyte antigen (HLA)-A*02:01-restricted glypican-3144–152 (FVGEFFTDV) and cytomegalovirus495–503 (NLVPMVATV) peptide-specific CTLs showed strong activity against all peptide-pulsed cell lines, regardless of whether the tumor cells expressed the antigen. In in vivo studies using immunodeficient mice, glypican-3144–152 and cytomegalovirus495–503 peptides injected into a solid mass were loaded onto HLA class I molecules of tumor cells. In a peptide vaccine model and an adoptive cell transfer model using C57BL/6 mice, intratumoral injection of ovalbumin257–264 peptide (SIINFEKL) was effective for tumor growth inhibition and survival against ovalbumin-negative tumors without adverse reactions. Moreover, we demonstrated an antigen-spreading effect that occurred after intratumoral peptide injection. Intratumoral peptide injection enhances tumor cell antigenicity and may be a useful option for improvement in antigen-specific cancer immunotherapy against solid tumors.
PMCID: PMC3624010  PMID: 23143746
Intratumoral peptide injection; Antigen; Immunotherapy; Cytotoxic T lymphocyte
11.  The small molecule TGF-β signaling inhibitor SM16 synergizes with agonistic OX40 antibody to suppress established mammary tumors and reduce spontaneous metastasis 
Effective tumor immunotherapy may require not only activation of anti-tumor effector cells, but also abrogation of tumor-mediated immunosuppression. The cytokine, TGF-β, is frequently elevated in the tumor microenvironment and is a potent immunosuppressive agent and promoter of tumor metastasis. OX40 (CD134) is a member of the TNF-α receptor superfamily and ligation by agonistic antibody (anti-OX40) enhances effector function, expansion and survival of activated T cells. In this study, we examined the therapeutic efficacy and anti-tumor immune response induced by the combination of a small molecule TGF-β signaling inhibitor, SM16, plus anti-OX40 in the poorly immunogenic, highly metastatic, TGF-β-secreting 4T1 mammary tumor model. Our data show that SM16 synergizes with anti-OX40 to elicit a potent anti-tumor effect against established primary tumors, with a 79% reduction in tumor size, a 95% reduction in the number of metastatic lung nodules and a cure rate of 38%. This positive treatment outcome was associated with a 3.2-fold increase of tumor-infiltrating, activated CD8+ T cells, an overall accumulation of CD4+ and CD8+ T cells, and an increased tumor-specific effector T cell response. Complete abrogation of the therapeutic effect in vivo following depletion of CD4+ and CD8+ T cells, suggests that the anti-tumor efficacy of SM16 + anti-OX40 therapy is T cell dependent. Mice that were cured of their tumors were able to reject tumor re-challenge and manifested a significant tumor-specific peripheral memory IFN-γ response. Taken together, these data suggest that combining a TGF-β signaling inhibitor with anti-OX40 is a viable approach for treating metastatic breast cancer.
PMCID: PMC3595193  PMID: 21971588
Breast cancer; 4T1; OX40; TGF-β; TGFβRI/ALK5; small molecule kinase inhibitor; SM16
12.  HPV associated tumor cells control tumor microenvironment and leukocytosis in experimental models 
Human papillomavirus (HPV) is the main etiological factor for cervical cancer development. HPV is also associated with other anogenital and oropharyngeal tumors. HPV associated tumors are frequent and constitute a public health problem, mainly in developing countries. Therapy against such tumors is usually excisional, causing iatrogenic morbidity. Therefore, development of strategies for new therapies is desirable. The tumor microenvironment is essential for tumor growth, where inflammation is an important component, displaying a central role in tumor progression. Inflammation may be a causal agent, suppressor of anti-tumor T cell responses, or may have a role in angiogenesis, drug resistance, and metastasis. The aim of this work was to investigate the role of HPV transformed cells in the tumor microenvironment and tumor effects on myeloid populations in lymphoid organs in the host. We used experimental models, where we injected cervical cancer derived cell lines in immunodeficient mice, comparing HPV positive, SiHa, and HeLa cells (HPV 16 and HPV18, respectively), with HPV negative cell line, C33A. Our data shows that HPV positive cell lines were more efficient than the HPV negative cell line in leukocyte recruitment to the tumor microenvironment and increase in myeloid cell proliferation in the bone marrow and spleen. We also observed that HPV positive cells lines expressed significantly higher levels of IL-6 and IL-8, while C33A expressed significantly higher levels of IL-16 and IL-17. Finally, in spite of cytokine secretion by tumor cells, leukocytes infiltrating SiHa and HeLa tumors displayed almost negligible STAT3 and no NFκB phosphorylation. Only the inflammatory infiltrate of C33A tumors had NFκB and STAT3 activated isoforms. Our results indicate that, although from the same anatomical site, the uterine cervix, these cell lines display important differences regarding inflammation. These results are important for the design of immunotherapies against cervical cancer, and possibly against HPV associated tumors in other anatomical sites.
PMCID: PMC4217549  PMID: 25400927
cervical cancer; cytokines; inflammation; human papillomavirus; leukocytosis
13.  Cellular immunotherapy using irradiated lung cancer cell vaccine co-expressing GM-CSF and IL-18 can induce significant antitumor effects 
BMC Cancer  2014;14:48.
Although the whole tumor cell vaccine can provide the best source of immunizing antigens, there is still a limitation that most tumors are not naturally immunogenic. Tumor cells genetically modified to secrete immune activating cytokines have been proved to be more immunogenic. IL-18 could augment proliferation of T cells and cytotoxicity of NK cells. GM-CSF could stimulate dendritic cells, macrophages and enhance presentation of tumor antigens. In our study, we used mouse GM-CSF combined with IL-18 to modify Lewis lung cancer LL/2, then investigated whether vaccination could suppress tumor growth and promote survival.
The Lewis lung cancer LL/2 was transfected with co-expressing mouse GM-CSF and IL-18 plasmid by cationic liposome, then irradiated with a sublethal dose X ray (100 Gy) to prepare vaccines. Mice were subcutaneously immunized with this inactivated vaccine and then inoculated with autologous LL/2 to estimate the antitumor efficacy.
The studies reported here showed that LL/2 tumor cell vaccine modified by a co-expressing mouse GM-CSF and IL-18 plasmid could significantly inhibit tumor growth and increased survival of the mice bearing LL/2 tumor whether prophylactic or adoptive immunotherapy in vivo. A significant reduction of proliferation and increase of apoptosis were also observed in the tumor treated with vaccine of co-expressing GM-CSF and IL-18. The potent antitumor effect correlated with higher secretion levels of pro-inflammatory cytokines such as IL-18, GM-CSF, interferon-γ in serum, the proliferation of CD4+ IFN-γ+, CD8+ IFN-γ+ T lymphocytes in spleen and the infiltration of CD4+, CD8+ T in tumor. Furthermore, the mechanism of tumor-specific immune response was further proved by 51Cr cytotoxicity assay in vitro and depletion of CD4, CD8, NK immune cell subsets in vivo. The results suggested that the antitumor mechanism was mainly depended on CD4+, CD8+ T lymphocytes.
These results provide a new insight into therapeutic mechanisms of IL-18 plus GM-CSF modified tumor cell vaccine and provide a potential clinical cancer immunotherapeutic agent for improved antitumor immunity.
PMCID: PMC3922726  PMID: 24475975
Cancer immunotherapy; IL-18; GM-CSF; Cell vaccine; Apoptosis
14.  Blockade of TGF-β enhances tumor vaccine efficacy mediated by CD8+ T cells 
Though TGF-β inhibition enhances anti-tumor immunity mediated by CD8+ T cells in several tumor models, it is not always sufficient for rejection of tumors. In the present study, to maximize the anti-tumor effect of TGF-β blockade, we tested the effect of anti-TGF-β combined with an irradiated tumor vaccine in a subcutaneous CT26 colon carcinoma tumor model. The irradiated tumor cell vaccine alone in prophylactic setting significant delayed tumor growth, whereas anti-TGF-β antibodies alone did not show any anti-tumor effect. However, tumor growth was inhibited significantly more in vaccinated mice treated with anti-TGF-β antibodies compared to vaccinated mice without anti-TGF-β suggesting that anti-TGF-β synergistically enhanced irradiated tumor vaccine efficacy. CD8+ T cell-depletion completely abrogated the vaccine efficacy, so protection required CD8+ T cells. Depletion of CD25+ T regulatory cells led to the almost complete rejection of tumors without the vaccine, whereas anti-TGF-β did not change the number of CD25+ T regulatory cells in un-vaccinated and vaccinated mice. Though the abrogation of CD1d-restricted NKT cells, which have been reported to induce TGF-β production by MDSC through an IL-13-IL-4R-STAT6 pathway, partially enhanced anti-tumor immunity regardless of vaccination, abrogation of the NKT cell-IL-13-IL-4R-STAT-6 immunoregulatory pathway did not enhance vaccine efficacy. Taken together, these data indicated that anti-TGF-β enhances efficacy of a prophylactic vaccine in normal individuals despite their not having the elevated TGF-β levels found in cancer patients and that the effect is not dependent on TGF-β solely from CD4+CD25+ T regulatory cells or the NKT cell-IL-13-IL-4R-STAT-6 immunoregulatory pathway.
PMCID: PMC2818422  PMID: 19830696
15.  The timing of TGF-β inhibition affects the generation of antigen-specific CD8+ T Cells 
BMC Immunology  2013;14:30.
Transforming growth factor (TGF)-β is a potent immunosuppressive cytokine necessary for cancer growth. Animal and human studies have shown that pharmacologic inhibition of TGF-β slows the growth rate of established tumors and occasionally eradicates them altogether. We observed, paradoxically, that inhibiting TGF-β before exposing animals to tumor cells increases tumor growth kinetics. We hypothesized that TGF-β is necessary for the anti-tumor effects of cytotoxic CD8+ T lymphocytes (CTLs) during the early stages of tumor initiation.
BALB/c mice were pretreated with a blocking soluble TGF-β receptor (sTGF-βR, TGF-β-blockade group, n=20) or IgG2a (Control group, n=20) before tumor inoculation. Tumor size was followed for 6 weeks. In vivo lymphocyte assays and depletion experiments were then performed to investigate the immunological basis of our results. Lastly, animals were pretreated with either sTGF-βR (n=6) or IgG2a (n=6) prior to immunization with an adenoviral vector encoding the human papillomavirus E7 gene (Ad.E7). One week later, flow cytometry was utilized to measure the number of splenic E7-specific CD8+ T cells.
Inhibition of TGF-β before the injection of tumor cells resulted in significantly larger average tumor volumes on days 11, 17, 22, 26 and 32 post tumor-inoculation (p < 0.05). This effect was due to the inhibition of CTLs, as it was not present in mice with severe combined immunodeficiency (SCID) or those depleted of CD8+ T cells. Furthermore, pretreatment with sTGF-βR inhibited tumor-specific CTL activity in a Winn Assay. Tumors grew to a much larger size when mixed with CD8+ T cells from mice pretreated with sTGF-βR than when mixed with CD8+ T cells from mice in the control group: 96 mm3 vs. 22.5 mm3, respectively (p < 0.05). In addition, fewer CD8+ T cells were generated in Ad.E7-immunized mice pretreated with sTGF-βR than in mice from the control group: 0.6% total CD8+ T cells vs. 1.9%, respectively (p < 0.05).
These studies provide the first in vivo evidence that TGF-β may be necessary for anti-tumor immune responses in certain cancers. This finding has important implications for our understanding of anti-tumor immune responses, the role of TGF-β in the immune system, and the future development of TGF-β inhibiting drugs.
PMCID: PMC3725164  PMID: 23865808
Malignant mesothelioma; Tumor immunology; Immune suppression; TGF-β; CD8+ Cytotoxic T cell
16.  Augmentation of Antitumor Immunity by Fusions of Ethanol-Treated Tumor Cells and Dendritic Cells Stimulated via Dual TLRs through TGF-β1 Blockade and IL-12p70 Production 
PLoS ONE  2013;8(5):e63498.
The therapeutic efficacy of fusion cell (FC)-based cancer vaccine generated with whole tumor cells and dendritic cells (DCs) requires the improved immunogenicity of both cells. Treatment of whole tumor cells with ethanol resulted in blockade of immune-suppressive soluble factors such as transforming growth factor (TGF)-β1, vascular endothelial growth factor, and IL-10 without decreased expression of major histocompatibility complex (MHC) class I and the MUC1 tumor-associated antigen. Moreover, the ethanol-treated tumor cells expressed “eat-me” signals such as calreticulin (CRT) on the cell surface and released immunostimulatory factors such as heat shock protein (HSP)90α and high-mobility group box 1 (HMGB1). A dual stimulation of protein-bound polysaccharides isolated from Coriolus versicolor (TLR2 agonist) and penicillin-inactivated Streptococcus pyogenes (TLR4 agonist) led human monocyte-derived DCs to produce HSP90α and multiple cytokines such as IL-12p70 and IL-10. Interestingly, incorporating ethanol-treated tumor cells and TLRs-stimulated DCs during the fusion process promoted fusion efficiency and up-regulated MHC class II molecules on a per fusion basis. Moreover, fusions of ethanol-treated tumor cells and dual TLRs-stimulated DCs (E-tumor/FCs) inhibited the production of multiple immune-suppressive soluble factors including TGF-β1 and up-regulated the production of IL-12p70 and HSP90α. Most importantly, E-tumor/FCs activated T cells capable of producing high levels of IFN-γ, resulting in augmented MUC1-specific CTL induction. Collectively, our results illustrate the synergy between ethanol-treated whole tumor cells and dual TLRs-stimulated DCs in inducing augmented CTL responses in vitro by FC preparations. The alternative system is simple and may provide a platform for adoptive immunotherapy.
PMCID: PMC3663747  PMID: 23717436
17.  Intratumoral Injection of Therapeutic HPV Vaccinia Vaccine Following Cisplatin Enhances HPV-specific Antitumor Effects 
Despite theconventional treatments of radiation therapy and chemotherapy, the five-year survival rates for patients withadvanced stage cervical cancers remain low. Cancer immunotherapy has emerged as an alternative, innovative therapythat may improve survival. Here we utilize a preclinical HPV-16 E6/E7-expressing tumor model, TC-1,and employ the chemotherapeutic agent cisplatin to generate an accumulation of CD11c+ dendritic cells in tumor loci making it an ideal location for the administration of therapeutic vaccines. Following cisplatin treatment, we tested different routes of administration of a therapeutic HPV vaccinia vaccine encoding HPV-16 E7 antigen (CRT/E7-VV).We found that TC-1tumor-bearing C57BL/6 mice treated with cisplatin and intratumoral injection of CRT/E7-VV significantly increased E7-specific CD8+ T cells in the blood and generated potent local and systemic antitumor immune responsescompared to mice receiving cisplatin and CRT/E7-VV intraperitoneally or mice treated with cisplatin alone. We further extended our study using a clinical grade recombinant vaccinia vaccine encoding HPV-16/18 E6/E7 antigens (TA-HPV).We found that intratumoral injection with TA-HPV following cisplatin treatment also led to increased E7-specific CD8+ T cells in the blood as well as significantly decreased tumor size compared to intratumoral injection with wild type vaccinia virus. Our study has strong implications for future clinical translation using intratumoralinjection of TA-HPV in conjunction with the current treatment strategies for patients with advanced cervical cancer.
PMCID: PMC3690484  PMID: 23615841
cisplatin; vaccine; vaccinia virus; human papillomavirus; TA-HPV
18.  Oncolytic measles viruses encoding interferon β and the thyroidal sodium iodide symporter gene for mesothelioma virotherapy 
Cancer Gene Therapy  2010;17(8):550-558.
Mesothelioma usually leads to death within 8–14 months of diagnosis. To increase the potency of oncolytic measles viruses (MVs) for mesothelioma therapy, we inserted the interferon β (IFNβ) gene alone or with the human thyroidal sodium iodide symporter (NIS) gene into attenuated MV of the Edmonston lineage. The corresponding mouse IFNβ (mIFNβ) viruses, MV-mIFNβ and MV-mIFNβ-NIS, successfully propagated in human mesothelioma cells, leading to intercellular fusion and cell death. High levels of mIFNβ were detected in the supernatants of the infected cells, and radioiodine uptake was substantial in the cells infected with MV-mIFNβ-NIS. MV with mIFNβ expression triggered CD68-positive immune cell infiltration 2–4 times higher than MV-GFP injected into the tumor site. The numbers of CD31-positive vascular endothelial cells within the tumor were decreased at day 7 after intratumoral injection of MV-mIFNβ or MV-mIFNβ-NIS, but not after MV-GFP and PBS administration. Immunohistochemical analysis showed that MV-mIFNβ changed the microenvironment of the mesothelioma by increasing innate immune cell infiltration and inhibiting tumor angiogenesis. Oncolytic MVs coding for IFNβ effectively retarded growth of human mesotheliomas and prolonged survival time in several mesothelioma tumor models. The results suggest that oncolytic MVs that code for IFNβ and NIS will be potent and versatile agents for the treatment of human mesothelioma.
PMCID: PMC2907639  PMID: 20379224
mesothelioma; oncolytic measles virus; interferon; thyroidal sodium iodide symporter
19.  Combined targeting of TGF-β1 and integrin β3 impairs lymph node metastasis in a mouse model of non-small-cell lung cancer 
Molecular Cancer  2014;13:112.
Transforming Growth Factor beta (TGF-β) acts as a tumor suppressor early in carcinogenesis but turns into tumor promoter in later disease stages. In fact, TGF-β is a known inducer of integrin expression by tumor cells which contributes to cancer metastatic spread and TGF-β inhibition has been shown to attenuate metastasis in mouse models. However, carcinoma cells often become refractory to TGF-β-mediated growth inhibition. Therefore identifying patients that may benefit from anti-TGF-β therapy requires careful selection.
We performed in vitro analysis of the effects of exposure to TGF-β in NSCLC cell chemotaxis and adhesion to lymphatic endothelial cells. We also studied in an orthotopic model of NSCLC the incidence of metastases to the lymph nodes after inhibition of TGF-β signaling, β3 integrin expression or both.
We offer evidences of increased β3-integrin dependent NSCLC adhesion to lymphatic endothelium after TGF-β exposure. In vivo experiments show that targeting of TGF-β and β3 integrin significantly reduces the incidence of lymph node metastasis. Even more, blockade of β3 integrin expression in tumors that did not respond to TGF-β inhibition severely impaired the ability of the tumor to metastasize towards the lymph nodes.
These findings suggest that lung cancer tumors refractory to TGF-β monotherapy can be effectively treated using dual therapy that combines the inhibition of tumor cell adhesion to lymphatic vessels with stromal TGF-β inhibition.
PMCID: PMC4049383  PMID: 24884715
Integrin; TGF-β; Metastases; Lymph nodes; Lymphatic vessels
20.  Development of Tumor-infiltrating CD8+ T cell Memory Precursor Effector Cells (MPECs) and Anti-melanoma Memory Responses are the Result of Vaccination and TGF-β Blockade During the Perioperative Period of Tumor Resection 
A main goal of cancer immunology research is the formation of antigen-specific memory T cell immunity capable of activation upon tumor re-encounter. The requirements necessary to overcome the inhibitory signals present in the tumor microenvironment and form such memory T cell responses are unknown. In contrast to previous studies targeting tumors expressing highly-immunogenic “model antigens,” we demonstrate that alleviating tumor-induced suppression along with vaccination against authentic antigens during the perioperative period provides long-lasting protection against a highly-suppressive and poorly-immunogenic melanoma. Here, we employed DNA vaccination with an immunologically optimized mouse melanoma-shared antigen, Trp1ee/ng, combined with systemic TGF-β blockade during the perioperative period of primary tumor resection, to confer protection against B16 melanoma, and against JBRH, an independently-derived melanoma unrelated to B16. Importantly, we demonstrate that correlative to memory responses, perioperative immunotherapy increases the formation of tumor-infiltrating and tumor-reactive CD8+ T cells expressing low levels of the transcription factor T-bet, defined as memory precursor effector cells (MPECs). We show that conditions for an “immunologically-fertile environment” are met when TGF-β blockade and vaccination are applied during the perioperative period of primary tumor resection. These findings address limitations of current CD8+ T cell immunotherapies against cancer by generating effective CD8+ T cell memory recall responses.
PMCID: PMC3048906  PMID: 21289306
21.  Distinct mechanisms of TGF-β1–mediated epithelial-to-mesenchymal transition and metastasis during skin carcinogenesis 
Journal of Clinical Investigation  2005;115(7):1714-1723.
In the present study, we demonstrated that human skin cancers frequently overexpress TGF-β1 but exhibit decreased expression of the TGF-β type II receptor (TGF-βRII). To understand how this combination affects cancer prognosis, we generated a transgenic mouse model that allowed inducible expression of TGF-β1 in keratinocytes expressing a dominant negative TGF-βRII (ΔβRII) in the epidermis. Without ΔβRII expression, TGF-β1 transgene induction in late-stage, chemically induced papillomas failed to inhibit tumor growth but increased metastasis and epithelial-to-mesenchymal transition (EMT), i.e., formation of spindle cell carcinomas. Interestingly, ΔβRII expression abrogated TGF-β1–mediated EMT and was accompanied by restoration of membrane-associated E-cadherin/catenin complex in TGF-β1/ΔβRII compound tumors. Furthermore, expression of molecules thought to mediate TGF-β1–induced EMT was attenuated in TGF-β1/ΔβRII–transgenic tumors. However, TGF-β1/ΔβRII–transgenic tumors progressed to metastasis without losing expression of the membrane-associated E-cadherin/catenin complex and at a rate higher than those observed in nontransgenic, TGF-β1–transgenic, or ΔβRII-transgenic mice. Abrogation of Smad activation by ΔβRII correlated with the blockade of EMT. However, ΔβRII did not alter TGF-β1–mediated expression of RhoA/Rac and MAPK, which contributed to increased metastasis. Our study provides evidence that TGF-β1 induces EMT and invasion via distinct mechanisms. TGF-β1–mediated EMT requires functional TGF-βRII, whereas TGF-β1–mediated tumor invasion cooperates with reduced TGF-βRII signaling in tumor epithelia.
PMCID: PMC1142114  PMID: 15937546
22.  Tumor-derived TGF-β and prostaglandin E2 attenuate anti-tumor immune responses in head and neck squamous cell carcinoma treated with EGFR inhibitor 
EGFR-targeted therapy is an attractive option for head and neck squamous cell carcinoma patients. We have recently reported the use of EGFR inhibitors as an adjunct treatment to enhance HLA-DR expression in tumor cells to improve cancer immunotherapy. Nevertheless, we observed that EGFR inhibitors resulted in decreased anti-tumor responses, regardless of upregulation of HLA-DR expression on the tumor cell. In this study, we specifically investigated the mechanisms by which EGFR inhibition modulated anti-tumor responses.
An EGFR inhibitor erlotinib was used to assess the modulation of anti-tumor responses by tumor antigen-specific helper T cells. We then examined whether administration of the EGFR inhibitor altered tumor cytokine profiles and expression of immune-related molecules on tumor cells.
Despite the augmented HLA-DR expression on a gingival cancer cell line by EGFR inhibition, anti-tumor responses of EGFR reactive helper T cell clones against tumor cells were decreased. EGFR inhibition did not change the expression of CD80, CD86, or PD-L1 on the tumor cells. Conversely, production of transforming growth factor beta (TGF-β) and prostaglandin E2 was increased by EGFR inhibition, indicating that these immunosuppressive molecules were involved in diminishing tumor recognition by T cells. Significantly, attenuation of HTL responses against tumors after EGFR inhibition was reversed by the addition of anti-TGF-β antibody or COX2 inhibitors.
Targeting TGF-β and prostaglandin E2 may allow for improved outcomes for cancer patients treated with combination immunotherapy and EGFR inhibitors.
PMCID: PMC4177691  PMID: 25240937
23.  Combination of SLC administration and Tregs depletion is an attractive strategy for targeting hepatocellular carcinoma 
Molecular Cancer  2013;12:153.
Secondary lymphoid tissue chemokine (SLC) is a key CC chemokine for chemotaxis of immune cells and has been an attractive candidate for anti-tumor treatments. However, among the immune cells recruited by SLC to tumors, the CD25+ Foxp3+ regulatory T cells (Tregs) compromise the anti-tumor effects. In this study, we proposed the combination therapy of intratumoral co-administration of SLC and anti-CD25 monoclonal antibodies (mAbs). We hypothesized that the intratumoral injections of SLC and depletion of Tregs would have stronger inhibition effects on the progression of hepatocellular carcinoma (HCC) in mice.
C57BL/6 mice were inoculated subcutaneously with the murine HCC cell line, and mice with visible tumors were treated intratumorally with SLC, SLC plus anti-CD25 mAbs or the control antibodies. The percentages of Tregs, effector CD8+ T cells and CD4+ T cells were checked in the tumors, lymph nodes, spleen and liver at regular intervals. The levels of intratumoral IL-12, IFN-γ, IL-10 and TGF-β1 were evaluated. The final anti-tumor effects were measured by the tumor volume and weight as well as the intratumoral activity of MMP2 and MMP9. Bone-marrow-derived dendritic cells were used to explore the mechanisms of maturation induced by SLC in vitro.
Our experiments showed the combination therapy significantly decreased the frequency of Tregs, and increased CD8+ T cells and CD4+ T cells at tumor sites. These alterations were accompanied by an increased level of IL-12 and IFN-γ, and decreased level of IL-10 and TGF-β1. Unexpectedly, we observed a significantly decreased percentage of Tregs, and increased CD8+ T cells and CD4+ T cells in the lymph nodes, spleen and liver after the combination therapy. The growth and invasiveness of HCC was also maximally inhibited in the combination therapy compared with the SLC alone. Furthermore, we confirmed SLC induced the maturation of DCs via NF-κB p65 and this maturation would benefit the combination therapy.
Our data demonstrated that intratumoral co-administration of SLC and anti-CD25 mAbs was an effective treatment for HCC, which was correlated with the altered tumor microenvironment and systemically optimized percentages of Tregs, CD8+ T cells and CD4+ T cells in peripheral immune organs.
PMCID: PMC3914677  PMID: 24304581
SLC; DCs; Tregs; HCC; Anti-tumor immunity
24.  Tumor-induced Immune Suppression of In Vivo T Effector Cell Priming is Mediated by the B7-H1/PD-1 Axis and TGF-β1 
Cancer research  2008;68(13):5432-5438.
We have generated effector T cells from tumor-draining lymph nodes that are efficacious in adoptive immunotherapy. We now examined the effect of concomitant tumors on the generation of effector T cells. We inoculated MCA 205 in the flanks of normal mice and mice bearing MCA 205 lung metastases. Tumor-draining lymph node cells from these mice were activated and expanded in vitro, and adoptively transferred to mice bearing lung metastases. Effector T cells (TDLN) generated from tumor-draining lymph nodes in mice with only flank tumor mediated potent antitumor activity. However, antitumor efficacy of the effector T cells generated from tumor-draining lymph nodes in mice with pre-existent lung tumor (cTDLN) was reduced. Phenotyping studies showed that dendritic cells in cTDLN expressed higher levels of B7-H1; while cTDLN T cells expressed higher levels of PD-1. The levels of IFNγ were reduced, and the levels of CD4+Foxp3+ regulatory T cells were increased from cTDLN vs. TDLN. The in vitro activation of cTDLN was increased by blocking B7-H1 or TGF-β. Importantly, we found a synergistic upregulation of IFNγ with simultaneous blockade of B7-H1 and TGF-β that was much greater than observed with TDLN. In vitro activation of cTDLN with anti-B7-H1 and anti-TGF-β and in vivo administration of these antibodies after adoptive transfer resulted in the abrogation of the suppression associated with cTDLN. These results demonstrate a major role of the B7-H1/PD-1 axis and TGF-β as synergistic suppressive mechanisms in cTDLN. Our data has clinical relevance in the generation of effector T cells in the tumor-bearing host.
PMCID: PMC3094850  PMID: 18593946
Adoptive immunotherapy; B7-H1; TGF-β; PD-1; Tregs
25.  Adoptive Transfer of siRNA Cblb-Silenced CD8+ T Lymphocytes Augments Tumor Vaccine Efficacy in a B16 Melanoma Model 
PLoS ONE  2012;7(9):e44295.
The ubiquitin ligase Cbl-b is an established regulator of T cell immune response thresholds. We recently showed that adoptive cell transfer (ACT) of cblb−/− CD8+ T cells enhances dendritic cell (DC) immunization-mediated anti-tumor effects in immune-competent recipients. However, translation of cblb targeting to clinically applicable concepts requires that inhibition of cblb activity be transient and reversible. Here we provide experimental evidence that inhibition of cblb using chemically synthesized siRNA has such potential. Silencing cblb expression by ex vivo siRNA transfection of polyclonal CD8+ T cells prior to ACT increased T cell tumor infiltration, significantly delayed tumor outgrowth, and increased survival rates of tumor-bearing mice. As shown by ex vivo recall assays, cblb silencing resulted in significant augmentation of intratumoral T cell cytokine response. ACT of cblb-silenced polyclonal CD8+ T cells combined with DC-based tumor vaccines predominantly mediated anti-tumor immune responses, whereas no signs of autoimmunity could be detected. Importantly, CBLB silencing in human CD8+ T cells mirrored the effects observed for cblb-silenced and cblb-deficient murine T cells. Our data validate the concept of enhanced anti-tumor immunity by repetitive ACT of ex vivo cblb siRNA-silenced hyper-reactive CD8+ T cells as add-on adjuvant therapy to augment the efficacy of existing cancer immunotherapy regimens in clinical practice.
PMCID: PMC3433477  PMID: 22962608

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