Adenovirus-mediated TNF-alpha gene transfer induces significant tumor regression in mice

Adenoviral Delivery of Tumor Necrosis Factor-α and Interleukin-2 Enables Successful Adoptive Cell Therapy of Immunosuppressive Melanoma

Adoptive T-cell transfer is a promising treatment approach for metastatic cancer, but efficacy in solid tumors has only been achieved with toxic pre- and postconditioning regimens. Thus, adoptive T-cell therapies would benefit from complementary modalities that enable their full potential without excessive toxicity. We aimed to improve the efficacy and safety of adoptive T-cell transfer by using adenoviral vectors for direct delivery of immunomodulatory murine cytokines into B16.OVA melanoma tumors with concomitant T-cell receptor transgenic OT-I T-cell transfer. Armed adenoviruses expressed high local and low systemic levels of cytokine when injected into B16.OVA tumors, suggesting safety of virus-mediated cytokine delivery. Antitumor efficacy was significantly enhanced with adenoviruses coding for murine interleukin-2 (mIL-2) and tumor necrosis factor-α (mTNFα) when compared with T-cell transfer alone or viruses alone. Further improvement in efficacy was achieved with a triple combination of mIL-2, mTNFα, and OT-I T-cells. Mechanistic studies suggest that mIL-2 has an important role in activating T-cells at the tumor, while mTNFα induces chemokine expression. Furthermore, adenovirus treatments enhanced tumor-infiltration of OT-I T-cells as demonstrated by SPECT/CT imaging of (111)In-labeled cells. Our results suggest the utility of cytokine-coding adenoviruses for improving the efficacy of adoptive T-cell therapies.

Targeting the tumor microenvironment to enhance antitumor immune responses

The identification of tumor-specific antigens and the immune responses directed against them has instigated the development of therapies to enhance antitumor immune responses. Most of these cancer immunotherapies are administered systemically rather than directly to tumors. Nonetheless, numerous studies have demonstrated that intratumoral therapy is an attractive approach, both for immunization and immunomodulation purposes. Injection, recruitment and/or activation of antigen-presenting cells in the tumor nest have been extensively studied as strategies to cross-prime immune responses. Moreover, delivery of stimulatory cytokines, blockade of inhibitory cytokines and immune checkpoint blockade have been explored to restore immunological fitness at the tumor site. These tumor-targeted therapies have the potential to induce systemic immunity without the toxicity that is often associated with systemic treatments. We review the most promising intratumoral immunotherapies, how these affect systemic antitumor immunity such that disseminated tumor cells are eliminated, and which approaches have been proven successful in animal models and patients.

Adenovirus-Based Vectors for the Development of Prophylactic and Therapeutic Vaccines

Emerging and reemerging infectious diseases as well as cancer pose great global health impacts on the society. Vaccines have emerged as effective treatments to prevent or reduce the burdens of already developed diseases. This is achieved by means of activating various components of the immune system to generate systemic inflammatory reactions targeting infectious agents or diseased cells for control/elimination. DNA virus-based genetic vaccines gained significant attention in the past decades owing to the development of DNA manipulation technologies, which allowed engineering of recombinant viral vectors encoding sequences for foreign antigens or their immunogenic epitopes as well as various immunomodulatory molecules. Despite tremendous progress in the past 50 years, many hurdles still remain for achieving the full clinical potential of viral-vectored vaccines. This chapter will present the evolution of vaccines from “live” or “attenuated” first-generation agents to recombinant DNA and viral-vectored vaccines. Particular emphasis will be given to human adenovirus (Ad) for the development of prophylactic and therapeutic vaccines. Ad biological properties related to vaccine development will be highlighted along with their advantages and potential hurdles to be overcome. In particular, we will discuss (1) genetic modifications in the Ad capsid protein to reduce the intrinsic viral immunogenicity, (2) antigen capsid incorporation for effective presentation of foreign antigens to the immune system, (3) modification of the hexon and fiber capsid proteins for Ad liver de-targeting and selective retargeting to cancer cells, (4) Ad-based vaccines carrying “arming” transgenes with immunostimulatory functions as immune adjuvants, and (5) oncolytic Ad vectors as a new therapeutic approach against cancer. Finally, the combination of adenoviral vectors with other non-adenoviral vector systems, the prime/boost strategy of immunization, clinical trials involving Ad-based vaccines, and the perspectives for the field development will be discussed.

Adenoviral vector-based strategies for cancer therapy

Definitive treatment of cancer has eluded scientists for decades. Current therapeutic modalities like surgery, chemotherapy, radiotherapy and receptor-targeted antibodies have varied degree of success and generally have moderate to severe side effects. Gene therapy is one of the novel and promising approaches for therapeutic intervention of cancer. Viral vectors in general and adenoviral (Ad) vectors in particular are efficient natural gene delivery systems and are one of the obvious choices for cancer gene therapy. Clinical and preclinical findings with a wide variety of approaches like tumor suppressor and suicide gene therapy, oncolysis, immunotherapy, anti-angiogenesis and RNA interference using Ad vectors have been quite promising, but there are still many hurdles to overcome. Shortcomings like increased immunogenicity, prevalence of preexisting anti-Ad immunity in human population and lack of specific targeting limit the clinical usefulness of Ad vectors. In recent years, extensive research efforts have been made to overcome these limitations through a variety of approaches including the use of conditionally-replicating Ad and specific targeting of tumor cells. In this review, we discuss the potential strengths and limitations of Ad vectors for cancer therapy.

Transgene expression of alpha tumor necrosis factor with mutations D142N and A144R under control of human telomerase reverse transcriptase promoter eradicates well-established tumors and induces long-term antitumor immunity

Recombinant adenoviral vectors (AdVTNF-alpha) expressing alpha tumor necrosis factor (TNF-alpha) under control of cytomegalovirus (CMV) promoter have been used in cancer gene therapy. To reduce its cytotoxicity, we constructed a recombinant AdV(TERT)mTNF-alpha expressing a mutant TNF-alpha (mTNF-alpha) with mutations at D142N and A144R under control of human telomerase reverse transcriptase (hTERT) promoter for treatment of well-established ovalbumin (OVA)-expressing murine B16 melanoma (BL6-10(OVA)) (6 mm in diameter). We demonstrated that the mTNF-alpha with mutations at D142N and A144R has less in vitro cytotoxicity, but maintains its functional effect in the stimulation of T-cell proliferation. The in vitro and in vivo transgene expressions under control of hTERT promoter are highly restricted in tumor cells compared with those under the control of the CMV promoter. AdV(TERT)mTNF-alpha gene therapy by intratumoral injection of AdV(TERT)mTNF-alpha vector (2 x 10(9) PFU) expressing the mutant mTNF-alpha under control of hTERT promoter reduces its in vivo toxicity, eradicates well-established BL6-10(OVA) tumors in 4/10 tumor-bearing mice, and induces OVA-specific CD8(+) T-cell-mediated long-term antitumor immunity. Therefore, AdV(TERT)mTNF-alpha gene therapy may be very useful in the immunotherapy of cancer.

Vaccination of fiber-modified adenovirus-transfected dendritic cells to express HER-2/neu stimulates efficient HER-2/neu-specific humoral and CTL responses and reduces breast carcinogenesis in transgenic mice

HER-2/neu transgene-modified dendritic cell (DC)-based vaccines are potent at eliciting HER-2/neu-specific antitumor immunity. In this study, we constructed a recombinant adenovirus (RGD)AdVneu with fiber gene modified by RGD insertion into the viral knob's H1 loop. We transfected DCs with (RGD)AdVneu, and assessed/compared HER-2/neu-specific humoral and cytotoxic T lymphocyte (CTL) responses and antitumor immunity derived from the original AdVneu-transfected DCs (DCneu1) and (RGD)AdVneu-transfected DCs (DCneu2). We demonstrated that DCneu2 displayed increased HER-2/neu expression by 8.3-fold compared to DCneu1. We also demonstrated that DCneu2 vaccination induced stronger HER-2/neu-specific humoral and CTL immune responses than DCneu1 vaccination. DCneu2 vaccination protected all the mice from HER-2/neu-expressing Tg1-1 tumor cell challenge in wild-type FVB/NJ mice, compared to a partial protection in DCneu1-immunized mice. In addition, DCneu2 vaccination also significantly delayed tumor growth than DCneu1 immunization (P<0.05) in Tg FVBneuN mice. Three immunizations of DCneu2 starting at the mouse age of 2 months also significantly delayed breast cancer development in Tg mice compared to DCneu2 vaccine (P<0.05). Importantly, DCneu2 vaccine reduced breast carcinogenesis by 9% in Tg mice with self HER-2/neu tolerance. Therefore, vaccination of fiber-modified adenovirus-transfected DCs to enhance expression of tumor antigens such as HER-2/neu is likely representative of a new direction in DC-based vaccine of breast cancer.

Engineered CD8+ cytotoxic T cells with fiber-modified adenovirus-mediated TNF-alpha gene transfection counteract immunosuppressive interleukin-10-secreting lung metastasis and solid tumors

T-cell suppression derived from tumor-secreted immunosuppressive interleukin (IL)-10 becomes a major barrier to CD8+ T-cell immunotherapy of tumors. Tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine capable of activating T and dendritic cells (DCs) and counteracting IL-10-mediated DC inhibition and regulatory T-cell-mediated immune suppression. In this study, we constructed a recombinant adenovirus (MF)AdVTNF with fiber-gene modified by RGD insertion into the viral knob's H1 loop and a melanoma cell line B16(OVA/IL-10) engineered to express ovalbumin (OVA) and to secrete IL-10 (2.2 ng/ml/10(6) cells/24 h). We transfected OVA-specific CD8+ T cells with (MF)AdVTNF, and found a fivefold increase in transgene human TNF-alpha secretion (4.3 ng/ml/10(6) cells/24 h) by the engineered CD8+ T(TNF) cells transfected with (MF)AdVTNF, compared to that (0.8 ng/ml/10(6) cells/24 h) by CD8+ T cells transfected with the original AdVTNF without viral fiber modification. The engineered CD8+ T(TNF) cells exhibited enhanced cytotoxicity and elongated survival in vivo after adoptive transfer. TNF-alpha derived from both the donor CD8+ T cells and the host cells plays an important role in donor CD8+ T-cell survival in vivo after adoptive transfer. We also demonstrated that the transfected B16(OVA/IL-10) tumor cells secreting IL-10 are more resistant to in vivo CD8+ T-cell therapy than the original B16(OVA) tumor cells without IL-10 expression. Interestingly, the engineered CD8+ T(TNF) cells secreting transgene-coded TNF-alpha, but not the control CD8+ T(control) cells without any transgene expression eradicated IL-10-secreting 12-day lung micrometastasis in all 10/10 mice and IL-10-secreting solid tumors ( approximately 5 mm in diameter) in 6/10 mice. Transfer of the engineered CD8+ T(TNF) cells further induced both donor- and host-derived memory CD8+ T cells, leading to a stronger long-term antitumor immunity against the IL-10-secreting B16(OVA/IL-10) tumor cell challenges. Therefore, CD8+ T cells engineered to secrete TNF-alpha may be useful when designing strategies for adoptive T-cell therapy of solid tumors.

Human dendritic cells engineered to express alpha tumor necrosis factor maintain cellular maturation and T-cell stimulation capacity

Dendritic cell (DC) vaccine has been demonstrated to induce antitumor immunity in animal models. It has been shown that the efficiency of antitumor immunity by DC vaccine is closely correlated with DC maturation status. The mature human DCs generated from peripheral blood mononuclear cells (PBMCs) in the presence of granulocyte macrophage-colony-stimulating factor (GM-CSF), interleukin (IL)-4, and tumor necrosis factor (TNF)-alpha have widely contributed to their growing use in cancer vaccination trials. Although the objective clinical immune responses have been observed, the treatment results have proved to be somewhat disappointing. One question of whether these ex vivo-generated mature DCs can maintain their maturation status in vivo after DC vaccination is unclear. In this study, we investigated the influence of different culture media (RPMI 1640/10% fetal calf serum [FCS] versus serum-free AIM-V medium) on DC maturation and the change of maturation status of these ex vivo generated mature DCs during further culturing in medium without inflammatory cytokine TNF-alpha. We previously constructed a recombinant adenovirus AdV-TNF-alpha expressing the transgene human TNF-alpha. We transfected human DCs with AdV-TNF-alpha at multiplicity of infection of 100, resulting in engineered DCs secreting TNF-alpha (4.6 ng/mL/10(6) cells/24 hours). We also conducted kinetic studies to compare the maturation status and the T-cell stimulation capacity by ex vivo-generated mature DCs and TNF-alpha- transgene-engineered DCs during further culturing in medium without TNF-alpha. Our data show that mature DCs can be generated from PBMCs in both Dulbecco's modified Eagle's medium plus 10% FCS and serum-free AIM-V medium containing GM-CSF (100 ng/mL), IL-4 (100 ng/mL), and TNF-alpha (10 ng/mL). However, these mature DCs gradually lost their maturity and became immature ones when culturing in medium in the absence of TNF-alpha. On the contrary, the human DCs engineered to express TNF-alpha can (i) stably maintain their cellular maturation and (ii) efficiently stimulate T-cell proliferation even during culturing ex vivo in medium without TNF-alpha stimulation. Therefore, DCs engineered to express TNF-alpha may also maintain their maturation status and induce more efficient antitumor immune responses when applied in vivo for vaccination. Thus, our results may be important in designing DC-based cancer vaccines in the future.

Vascular endothelial growth inhibitor (VEGI), an endogenous negative regulator of angiogenesis

Vascular endothelial growth inhibitor (VEGI; TNFSF-15) is a new member of the tumor necrosis factor family. VEGI is predominantly an endothelial cell-specific gene, and recombinant VEGI is a potent inhibitor of endothelial cell proliferation, angiogenesis and tumor growth. VEGI exerts two activities on endothelial cells: early G1 arrest of G0/G1-cells responding to growth stimuli, and programmed death of proliferating cells. These activities are highly specific to endothelial cells. There are three VEGI isoforms identified thus far. One of the isoforms, VEGI-251, is a secreted protein. The gene products apparently play a role in normal vasculature, as the transcripts are found in normal adult tissues and some fetal tissues. VEGI gene expression is subject to regulation by inflammatory cytokines. VEGI is also able to regulate the expression of several important genes involved in angiogenesis. These findings are consistent with the view that VEGI functions as an autocrine cytokine to inhibit angiogenesis and stabilize the vasculature.

HER-2/neu-gene engineered dendritic cell vaccine stimulates stronger HER-2/neu-specific immune responses compared to DNA vaccination

HER-2/neu is a candidate for developing breast cancer-targeted immunotherapeutics. Although DNA-based and HER-2/neu transgene-modified dendritic cell (DC)-based vaccines are potent at eliciting HER-2/neu-specific antitumor immunity, there has been no side-by-side study comparing them directly. The present study utilizes an in vivo murine tumor model expressing HER-2/neu antigen to compare the efficacy between adenovirus (AdVneu)-transfected dendritic cells (DC(neu)) and plasmid DNA (pcDNAneu) vaccine. Our data showed that DC(neu) upregulated the expression of immunologically important molecules and inflammatory cytokines and partially converted regulatory T (Tr)-cell suppression through interleukin-6 (IL-6) secretion. Vaccination of DC(neu) induced stronger HER-2/neu-specific humoral and cellular immune responses than DNA vaccination, which downregulated HER-2/neu expression and lysed HER-2/neu-positive tumor cells in vitro, respectively. In two HER-2/neu-expressing tumor models, DC(neu) completely protected mice from tumor cell challenge compared to partial or no protection observed in DNA-immunized mice. In addition, DC(neu) significantly delayed breast cancer development in transgenic mice in comparison to DNA vaccine (P<0.05). Taken together, we have demonstrated that HER-2/neu-gene-modified DC vaccine is more potent than DNA vaccine in both protective and preventive animal tumor models. Therefore, DCs genetically engineered to express tumor antigens such as HER-2/neu represent a new direction in DC vaccine of breast cancer.

Combinational adenovirus-mediated gene therapy and dendritic cell vaccine in combating well-established tumors

Recent developments in tumor immunology and biotechnology have made cancer gene therapy and immunotherapy feasible. The current efforts for cancer gene therapy mainly focus on using immunogenes, chemogenes and tumor suppressor genes. Central to all these therapies is the development of efficient vectors for gene therapy. By far, adenovirus (AdV)-mediated gene therapy is one of the most promising approaches, as has confirmed by studies relating to animal tumor models and clinical trials. Dendritic cells (DCs) are highly efficient, specialized antigen-presenting cells, and DC-based tumor vaccines are regarded as having much potential in cancer immunotherapy. Vaccination with DCs pulsed with tumor peptides, lysates, or RNA, or loaded with apoptotic/necrotic tumor cells, or engineered to express certain cytokines or chemokines could induce significant antitumor cytotoxic T lymphocyte (CTL) responses and antitumor immunity. Although both AdV-mediated gene therapy and DC vaccine can both stimulate antitumor immune responses, their therapeutic efficiency has been limited to generation of prophylactic antitumor immunity against re-challenge with the parental tumor cells or to growth inhibition of small tumors. However, this approach has been unsuccessful in combating well-established tumors in animal models. Therefore, a major strategic goal of current cancer immunotherapy has become the development of novel therapeutic strategies that can combat well-established tumors, thus resembling real clinical practice since a good proportion of cancer patients generally present with significant disease. In this paper, we review the recent progress in AdV-mediated cancer gene therapy and DC-based cancer vaccines, and discuss combined immunotherapy including gene therapy and DC vaccines. We underscore the fact that combined therapy may have some advantages in combating well-established tumors vis-a-vis either modality administered as a monotherapy.

Silencing of human phosphatidylethanolamine-binding protein 4 sensitizes breast cancer cells to tumor necrosis factor-alpha-induced apoptosis and cell growth arrest

PURPOSE

The current therapeutic approach is not so effective in breast cancer patients. Alternative treatment protocols aimed at different targets need to be explored. We recently reported a novel phosphatidylethanolamine-binding protein, human phosphatidylethanolamine-binding protein 4 (hPEBP4), as an antiapoptotic molecule. The finding led us to explore a promising approach for breast cancer therapy via silencing the expression of hPEBP4.

EXPERIMENTAL DESIGN

hPEBP4 expression in clinical breast specimens was examined by Tissue Microarrays. RNA interference was used to silence hPEBP4 expression in MCF-7 breast carcinoma cells and the effects on cell proliferation, cell cycle progression, apoptosis, as well as underlying mechanisms, were investigated.

RESULTS

hPEBP4 was found to be expressed in up to 50% of breast cancers but in only <4% of normal breast tissues. Silencing of hPEBP4 potentiated tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis and cell cycle arrest in MCF-7 cells, which was due to the increased mitogen-activated protein kinase activation and the enhanced phosphatidylethanolamine externalization. Further investigation showed that silencing of hPEBP4 in MCF-7 cells promoted TNF-alpha-induced stability of p53, up-regulation of phospho-p53ser15, p21waf/cip, and Bax, and down-regulation of Bcl-2 and Bcl-xL, which were shown to depend on extracellular signal-regulated kinase 1/2 and c-jun NH2-terminal kinase activation by hPEBP4 silencing. Moreover, the increased proportion of cells in the G0-G1 phase of cell cycle was observed in hPEBP4-silenced MCF-7 cells on TNF-alpha treatment and the expression of cyclin A and cyclin E was down-regulated more significantly.

CONCLUSIONS

The antiapoptotic effect and the preferential expression pattern in breast cancer tissues make hPEBP4 a new target for breast cancer therapy. Silencing of hPEBP4 expression may be a promising approach for the treatment of breast carcinoma.

Significant tumor regression induced by microencapsulation of recombinant tumor cells secreting fusion protein

Implantation of microencapsulated engineered cells secreting molecules with antineoplastic properties into tumors is a novel approach to cancer gene therapy. In this study, we constructed an engineered tumor cell line, VkCk/RM4-TNF-alpha, which secreted RM4/TNF-alpha fusion protein containing the chimeric antitumor antibody, F(ab')2 (RM4), recognizing the tumor antigen TAG72, as well as the TNF-alpha moiety. The engineered cells were encapsulated into microencapsules. The RM4/TNF-alpha fusion protein secreted by encapsulated VkCk/RM4-TNF-alpha cells could be diffused through the microencapsule membrane into the supernatant and exert a cytotoxic effect on L929 cells in vitro. The antigen-specific binding-reactivity of RM4/TNF-alpha for the TAG72 antigen was confirmed by immunohistochemical staining of rat LMCR tumor cells which expressed TAG72 antigen. Implantation of microencapsules containing VkCk/RM4-TNF-alpha cells into LMCR tumors in rats induced tumor regression as a result of tumor necrosis formation. Taken together, these data suggest that microencapsulation of recombinant tumor cells secreting antibody/cytokine fusion protein might be an alternative approach in the treatment of cancers.

Intratumoral administration of immature dendritic cells following the adenovirus vector encoding CD40 ligand elicits significant regression of established myeloma

Our previous study showed that J558 myeloma cells engineered CD40L lost their tumorigenicity in syngeneic mice, and the inoculation of J558/CD40L tumor cells further led to the protective immunity against wild tumors. In the present study, we investigated whether the vaccine can exert more efficient antitumor immunity by combination with adenovirus mediated CD40L gene therapy and immature dendritic cells (iDCs). The results demonstrated that intratumoral administration of iDCs 2 days after AdVCD40L injection, not only significantly suppressed the tumor growth, but also eradiated the established tumors in 40% of the mice. The potent antitumor effect produced by the combination therapy correlated with high expression of MHC, costimulatory and Fas molecules on J558 cells, which was derived from CD40L transgene expression. In addition, transgene CD40L expression could dramatically induce J558 cell apoptosis. Effectively capturing apoptotic bodies by iDCs in vivo could induce DC maturation, prime tumor-specific CTLs and tend to Th1-type immune response. Finally, in vivo depletion experimentation suggested both CD4+ and CD8+ T cells were involved in mediating the antitumor immune responses of combined treatment of AdVCD40L and iDCs, with CD8+ T cells being the major effector. These findings could be beneficial for designing strategies of DCs vaccine and CD40L for anticancer immunotherapy.

A comprehensive in vitro characterization of pancreatic ductal carcinoma cell line biological behavior and its correlation with the structural and genetic profile

There are a large number of stable pancreatic ductal carcinoma cell lines (PDCL) that are used by researchers worldwide. Detailed data about their differentiation status and genetic alterations are present in the literature, but a systematic correlation with cell biological behavior is often lacking. PDCL ( n=12) were clustered by source of tumor cell (ascites, primary tumor, metastasis), and the data of functional cell biology were correlated with the reported structural and genetic profiles. Major histocompatibility complex expression, chemosensitivity and aneuploidia appeared to be related to the source of PDCL, and proliferative capacity appeared to be related to the grade of differentiation. No correlation between genetic/structural features of PDCL and biological behavior was found. All the cell lines appeared generally insensitive to in vitro treatment with 5-fluorouracil and showed variable degrees of susceptibility to gemcitabine, raltitrexed and oxaliplatin. All the PDCL showed resistance to Fas-mediated apoptosis but were significantly sensitive to the pro-apoptotic effect of inflammatory cytokines [interleukin (IL)-1beta, tumor necrosis factor (TNF)alpha and interferon gamma]. PDCL were characterized for the secretion of several factors relevant to the tumor-immune cross talk. Vascular endothelial growth factor, CCL2, CCL5 and transforming growth factor beta were the factors most frequently released; less frequent was the secretion of CXCL8, CCL22, IL-6 and sporadically CXCL12, IL-10 and hepatocyte growth factor. The cytokines IL-1beta and TNFalpha were always undetectable. In conclusion, a clear correlation between structural/genetic features and function could not be detected, suggesting the weakness of a "morphological" classification for the in vitro studies of pancreatic cancer.

Dendritic cells engineered to express the Flt3 ligand stimulate type I immune response, and induce enhanced cytoxic T and natural killer cell cytotoxicities and antitumor immunity

BACKGROUND

Tumor antigen presentation by dendritic cells (DCs) to T cells in lymphoid organs is crucial for induction of antitumor immune responses. Fms-like tyrosine kinase 3 ligand (Flt3L) is a regulator of hematopoietic cell development.

METHODS

To investigate the potential effect of Flt3L transgene expression on DC-based cancer vaccines, we constructed a recombinant adenovirus AdVFlt3L expressing Flt3L, transfected DCs with AdVFlt3L, and investigated the efficacy of antitumor immunity by vaccination of DC(Flt3L) engineered to express Flt3L transgene.

RESULTS

Our data demonstrated that AdVFlt3L transfection up-regulated the expression of cytokine IL-1beta and chemokines MIP-1alpha, MIP-1beta, IP-10, MCP-1 and MIP-2, and stimulated DC(Flt3L) cell proliferation in vitro and migration toward regional lymph nodes in vivo. Our data also demonstrated that vaccination of Mut1-pulsed DC(Flt3L) cells was able to stimulate (i). a type 1 immune response comprising CD4(+) Th1 and CD8(+) Tc1 activation and (ii). around 2- and 3-fold enhanced tumor-specific cytotoxic T lymphocyte (CTL) and non-specific NK responses (p < 0.05) than vaccination with similarly pulsed control virus-transfected and untransfected DCs, respectively. More importantly, vaccination of Mut1-pulsed DC(Flt3L) cells induced enhanced antitumor immunity in vivo, even against poorly immunogenic 3LL tumor cells. Vaccinations of Mut1-pulsed DCs, DC(pLpA) and DC(Flt3L) all protected mice from challenge of low dose (0.5 x 10(5)) tumor cells. However, only vaccination of the last one was able to protect 63% (6/8) mice from challenge of high dose (3 x 10(5)) 3LL tumor cells (p < 0.01).

CONCLUSIONS

DCs engineered to secrete Flt3L may offer a new strategy in DC-based cancer vaccines.

Cyclin E overexpression enhances cytokine-mediated apoptosis in MCF7 breast cancer cells

Cyclin E, the regulatory component of the cyclin E/cyclin-dependent kinase (CDK) complex, is required for proliferation and overexpression of this cyclin is associated with many types of human tumors. To elucidate the mechanism by which cyclin E overexpression promotes tumorigenesis, cyclin E was overexpressed in two breast cancer lines: MCF7 and T47D. Cells overexpressing cyclin E display a marked decrease in the expression of Bcl-2, an antiapoptotic protein, and increased levels of the proapoptotic proteins Bad and Bax. The levels of Bcl-X(L) and Mcl-1 remain unchanged. Since the homeostasis of pro- and antiapoptotic proteins was altered, we asked if cyclin E overexpression modifies responses to cytokines. MCF7 cyclin E overexpressing cells have an enhanced sensitivity to Fas, TRAIL, and TNF-alpha-induced apoptosis. T47D cells overexpressing cyclin E have a significant increase in TNF-alpha and TRAIL-induced apoptosis. In conclusion, our results provide a link between expression of cyclin E, deregulation of Bcl-2, and an altered response to cytokine-mediated apoptosis.

Tumour necrosis factor-alpha (TNF-alpha) transgene-expressing dendritic cells (DCs) undergo augmented cellular maturation and induce more robust T-cell activation and anti-tumour immunity than DCs generated in recombinant TNF-alpha

Tumour antigen presentation by dendritic cells (DCs) to T cells in lymphoid organs is crucial for induction of anti-tumour immune responses. It has been previously reported that tumour necrosis factor-alpha (TNF-alpha) is required for DC activation and subsequent induction of optimal immune responses, and thus DCs for anti-tumour vaccination are often generated by culture in exogenous TNF-alpha. In the present study, we investigated the effect on anti-tumour immunity of vaccination with Mut1 tumour peptide-pulsed DCs engineered to express a TNF-alpha transgene. Our data shows that transfection of DCs with recombinant adenovirus AdV-TNF-alpha resulted in greater maturation of the DCs than occurred with control DCs cultured in exogenous TNF-alpha, as determined by up-regulated expression of pro-inflammatory cytokines (e.g. interleukins 1beta and 18), chemokines [e.g. interferon-gamma-inducible protein-10 and macrophage inflammatory protein-1beta (MIP-1beta)], the CC chemokine receptor CCR7, and immunologically important cell surface molecules (CD40, CD86 and intercellular adhesion molecule-1). These transgenic DCs stimulated stronger allogeneic T-cell responses in vitro and T-cell activation in vivo; displayed 2.4-fold enhanced chemotactic responses to the MIP-3betain vitro (P<0.05); and, perhaps most importantly, trafficked into the draining lymph nodes dramatically (seven-fold, P<0.01) more efficiently than the control DCs. Our data also demonstrate that vaccination of mice with Mut1 peptide-pulsed, AdV-TNF-alpha-transfected DCs stimulated more efficient in vitro Mut1-specific CD8+ cytotoxic T-cell responses and solid tumour immunity in vivo, when compared to the in vitro TNF-alpha-cultivated DCs. Thus, DCs engineered to secrete TNF-alpha may offer a new strategy in DC cancer vaccines.

The acute and sensitization effects of tumor necrosis factor-α: implications for immunotherapy as well as psychiatric and neurological conditions

In addition to their role as signaling molecules of the immune system, cytokines may participate in central neurotransmission. Variations of the central and/or peripheral levels of the proinflammatory cytokines, tumor necrosis factor-α (TNF-α) and interleukin-β (IL-1β), impact on neuroendocrine processes as well as central neurotransmitter activity. To a considerable extent, these effects are reminiscent of those elicited by psychogenic stressors. The current review describes recent findings consistent with a role for these cytokines in the neurochemical and behavioral manifestations of clinical depression, as well as the cellular death associated with cerebral ischemia. Moreover, the increasing use of cytokines in the immunotherapeutic treatment of various autoimmune diseases (e.g. rheumatoid arthritis) and cancers prompted us to consider the potential role of central processes in subserving the mood-related side-effects elicited by these treatments. Finally, a single administration of TNF-α has been shown to elicit a time-dependent sensitization effect, wherein the behavioral and neurochemical responses elicited by later cytokine treatment are greatly enhanced. Thus, particular attention was devoted to the possibility that elevated levels of TNF-α, through either exogenous (e.g. immunotherapy) or endogenous (e.g. brain damage or stressors) means may sensitize neurotransmitter or second messenger pathways important for the pathology. Given the time-dependent nature of cytokine sensitization effects, the schedule of cytokine administration during immunotherapy, or the timing of cytokine up-regulation in response to traumatic or stressful events may favor the development of sensitized central processes, which may influence clinical outcome.

TNFerade Biologic: preclinical toxicology of a novel adenovector with a radiation-inducible promoter, carrying the human tumor necrosis factor alpha gene

TNFerade Biologic (TNFerade) is a second-generation (E1-, E3-, and E4-deleted) replication-deficient adenovector carrying the transgene encoding for human tumor necrosis factor alpha (TNFalpha), regulated by the radiation-sensitive promoter Early Growth Response (Egr-1). We hypothesized that intratumoral injection of TNFerade followed by radiation would result in potentially therapeutic levels of TNFalpha with minimal toxicity. Three preclinical studies were conducted, the purpose of which was to characterize the toxicity and pharmacokinetics of TNFerade in conjunction with radiation in nude as well as immune-competent (Balb/c) mice. A total of 80 mice in the nude mouse toxicology study, all bearing human squamous cell carcinoma xenografts, 120 mice in the Balb/c study, and 33 nude mice in the pharmacokinetic study were used. Doses ranging from 4x10(9) to 4x10(10) particle units (pu) (4x10(11) pu in the Balb/c study) were explored, with and without radiation. In the nude mice studies, TNFerade was injected intratumorally, whereas in the Balb/c study, TNFerade was administered by subcutaneous injection. TNFerade was well tolerated. In the nude mice studies, no significant toxicity occurred in any dose group. In the Balb/c study, 6/40 mice at the top dose (4x10(11) pu) were sacrificed in moribund condition (5/20 in the TNFerade+radiation group, 1/20 in the TNFerade alone group). Necropsy showed local necrosis and ulceration at the site of the injection. No deaths or significant toxicity were observed at the lower dose levels (4x10(9) and 4x10(10) pu), indicating a large safety margin for initial studies in humans. The pharmacokinetic study demonstrated high sustained levels of TNFalpha in the tumor homogenate with no "spillover" to plasma, where TNFalpha levels were below the level of detection. Radiation increased intratumoral levels of TNFalpha by a factor of 12 (from 0.998 to 11.55 ng/g). In conclusion, a gene therapy approach with TNFerade, in combination with radiation, represents a potential way to utilize the potent anticancer activity of TNFalpha without systemic toxicity.

Enhanced HER-2/neu-specific antitumor immunity by cotransduction of mouse dendritic cells with two genes encoding HER-2/neu and alpha tumor necrosis factor

The present study uses an in vivo murine tumor model expressing the human HER-2/neu antigen to evaluate the potential vaccine using dendritic cells (DCs) infected with adenovirus AdVHER-2. We first investigated whether infected DCs (DC(HER-2)) engineered to express HER-2/neu could induce HER-2/neu-specific immune responses. Our data showed that (i) AdVHER2-infected DC(HER-2) expressed HER-2/neu by Western blot and flow cytometric analysis, and (ii) vaccination of mice with DC(HER-2) induced HER-2/neu-specific cytotoxic T-lymphocyte (CTL) responses, but protected only 25% of vaccinated mice from challenge of 3 x 10(5) MCA26/HER-2 tumor cells. Further, to enhance the efficacy of DC(HER-2) vaccine, we coinfected DCs with both AdVHER-2 and AdVTNF-alpha. The infected DCs (DC(HER-2/TNF-alpha)) displayed the expression of both HER-2/neu and TNF-alpha by flow cytometric and ELISA analysis. We next investigated whether DC(HER-2/TNF-alpha) could induce stronger HER-2/neu-specific immune responses. We found that DC(HER-2/TNF-alpha) displayed up-regulation of immunologically important CD40, CD86, and ICAM-I molecules compared with DC(HER-2), indicating that the former ones are more mature forms of DCs. Vaccination of DC(HER-2/TNF-alpha) induced stronger allogeneic T-cell proliferation and 36% enhanced HER-2/neu-specific T-cell responses in vitro than DC(HER-2) cells. More importantly, it stimulated the significant anti-HER-2/neu immunity in vivo, which protected 8/8 mice from challenge of 3 x 10(5) MCA26/HER-2 tumor cells. Therefore, DCs genetically engineered to express both the tumor antigen and cytokines such as TNF-alpha as an immunoadjuvant are likely to represent a new direction in DC vaccine of cancer.

Intratumoral coinjection of two adenoviral vectors expressing functional interleukin-18 and inducible protein-10, respectively, synergizes to facilitate regression of established tumors

We have constructed two recombinant adenoviral vectors AdVIP-10 and AdVIL-18 expressing the functional chemokine IFN-gamma inducible protein (IP)-10 and cytokine interleukin (IL)-18, respectively. Injection of either AdVIP-10 or AdVIL-18 subcutaneously into tumor nodules derived from the J558 murine myeloma cell line delayed some tumor growth but it was not curative in all cases. Coinjection of these two vectors at the same tumor nodule not only significantly suppressed the tumor growth, but also cured established tumors in 8 of 10 (80% tumor free) mice. The latter treatment stimulated T-cell infiltration into tumors in association with tumor necrosis formation, induced a type 1 immune response and induced the activation of J558 tumor-specific cytotoxic T lymphocytes. Moreover, the antitumor activity of IP-10 and IL-18 combined gene therapy was significantly diminished in mice with depletion of either CD4(+) (50% tumor free) or CD8(+) (40% tumor free) T cells, and completely lost (0% tumor free) in T cell-deficient nude and IFN-gamma knockout mice, indicating the critical roles of T cells and IFN-gamma in this therapeutical model. Taken together, the findings of this study demonstrate that the combined use of two adenoviral vectors expressing IP-10 and IL-18, respectively, synergize to facilitate regression of established tumors. These observations also suggest the potential use of double-recombinant adenoviral vectors expressing chemokines and immunomodulatory cytokines in cancer gene therapy.

Synergistic effect of adoptive T-cell therapy and intratumoral interferon gamma-inducible protein-10 transgene expression in treatment of established tumors

The lack of efficient T-cell infiltration of tumors is a major obstacle to successful adoptive T-cell therapy. We have previously shown that transplanted SP2/0 myeloma tumors engineered to express lymphotactin invariably induced tumor regress mediated by SP2/0 tumor-specific T cells. Herein, we further systemically characterize these activated T cells and investigate their therapeutic efficacy, either alone or with the chemokine interferon gamma (IFN-gamma)-inducible protein-10 (IP-10) gene therapy. Following stimulation with SP2/0 cells, these activated T cells were CD25(+)FasL(+) L-selectin(low), expressed CXCR3 receptor and were chemoattracted by IP-10 in vitro. They comprised 64% CD4(+) Th1 and 36% CD8(+) Tc1 cells, both of which expressed IFN-gamma, perforin, and TNF-alpha, but not IL-4. The activated T cells were strongly cytotoxic for SP2/0 tumor cells (79% specific killing; E:T ratio, 50), mainly via perforin-mediated pathway. Cell tracking using labeled T cells confirmed that these T cells infiltrated better into the IP-10-expressing tumors than non-IP-10-expressing ones. In vivo, combined intratumoral IP-10 gene transfer and adoptive T-cell immunotherapy for well-established SP2/0 tumors eradicated the tumors in 7 of the 8 mice. Control or IP-10 adenoviral treatments by themselves neither alter the lethal outcome for tumor-bearing mice nor did T-cell therapy by itself, although the latter two treatments did slow its time-frame. Taken together, our data provide solid evidence of a potent synergy between adoptive T-cell therapy and IP-10 gene transfer into tumor tissues, which culminated in the eradication of well-established tumor masses.

A novel secreted splice variant of vascular endothelial cell growth inhibitor

Vascular endothelial cell growth inhibitor (VEGI), a member of the tumor necrosis factor (TNF) family, is an endothelial cell-specific inhibitor of angiogenesis. Overexpression by cancer cells of a secretable VEGI fusion protein resulted in abrogation of xenograft tumor progression, but overexpression of full-length VEGI was completely without effect. This finding indicates that secretion is essential for VEGI action. Here we report the identification of two new VEGI isoforms consisting of 251 and 192 amino acid residues. Both isoforms show endothelial cell-specific expression and share a C-terminal 151-residue segment with the previously described VEGI, which comprises 174 residues. The isoforms are generated from a 17 kb human gene by alternative splicing. Their expression is regulated in parallel by inflammatory cytokines TNF-alpha and interferon-gamma. VEGI-251, the most abundant isoform, contains a putative secretion signal. VEGI protein is detected in conditioned media of endothelial cells and VEGI-251-transfected mammalian cells. Overexpression of VEGI-251 in endothelial cells causes dose-dependent cell death. VEGI-251-transfected cancer cells form xenograft tumors of reduced growth rate and microvessel density compared with tumors of empty vector transfectants. These findings support the view that endothelial cell-secreted VEGI may function as an autocrine inhibitor of angiogenesis and a naturally existing modulator of vascular homeostasis.

Adenovirus-mediated CD40 ligand gene-engineered dendritic cells elicit enhanced CD8(+) cytotoxic T-cell activation and antitumor immunity

CD40L, the ligand for CD40 on dendritic cells (DCs), plays an important role in their activation and is essential for induction of antigen-specific T-cell responses. In the present study, we investigated the efficacy of antitumor immunity induced by vaccination with DCs engineered to express CD40L and pulsed with Mut1 tumor peptide. Our data show that transfection of DCs with recombinant adenovirus AdV-CD40L resulted in activation of DCs with up-regulated expression of proinflammatory cytokines (IL-1beta and IL-12), chemokines (RANTES, IP-10, and MIP-1alpha), and immunologically important cell surface molecules (CD54, CD80, and CD86). Our data also demonstrate that DCs transfected with AdV-CD40L (DC(CD40L)) are able to stimulate enhanced allogeneic T-cell proliferation and Mut1-specific CD8(+) cytotoxic T-cell responses in vitro. Vaccination of mice with Mut1 peptide-pulsed control virus-transfected DC (DC(pLpA)) could only protect mice from challenge of a low dose (0.5 x 10(5) cells per mouse, 8/8 mice), but not a high dose (3 x 10(5) cells per mouse, 0/8 mice) of 3LL tumor cells. However, vaccination of Mut1 peptide-pulsed AdV-CD40L-transfected DC(CD40L) induced an augmented antitumor immunity in vivo by complete protection of mice (8/8) from challenge of both low and high doses of 3LL tumor cells. Thus, DCs engineered to express CD40L by adenovirus-mediated CD40 ligand gene transfer may offer a new strategy in production of DC cancer vaccines.

Intratumoral administration of low doses of an adenovirus vector encoding tumor necrosis factor alpha together with naive dendritic cells elicits significant suppression of tumor growth without toxicity

Although tumor necrosis factor alpha (TNF-alpha) is a potent cytokine with a myriad of innate immune antitumor properties, systemic administration of TNF-alpha is associated with significant toxicity, limiting the use of the TNF-alpha protein as an antitumor therapeutic. On the basis of the knowledge that dendritic cells (DCs) play a central role in initiating antitumor adaptive immune responses, we hypothesized that intratumoral administration of low doses of an adenovirus encoding TNF-alpha (AdTNF-alpha) together with syngeneic DCs would act synergistically to suppress preexisting tumors. As a model, four different tumor cell lines, all resistant in vitro to the TNF-alpha protein, were implanted in syngeneic mice, and established tumors received intratumor AdTNF-alpha alone or in combination with DCs. At high doses (10(9) PFU), AdTNF-alpha alone suppressed tumor growth, but was associated with systemic toxicity. A 100-fold lower AdTNF-alpha concentration (10(7) PFU) or high doses of the control vector AdNull had no systemic toxicity, but also minimal suppression of tumor growth. In contrast, local administration of the low dose (10(7) PFU) of AdTNF-alpha in combination with syngeneic DCs (AdTNF-alpha + DCs) elicited marked tumor suppression without toxicity. Administration of AdTNF-alpha + DCs into tumors elicited tumor-specific cytotoxic T cells and protected animals against subsequent challenge with the same tumor, suggesting that AdTNF-alpha + DC therapy induced tumor-specific adaptive immune host responses. Consistent with this concept, studies with syngeneic knockout mice showed that MHC class I molecules on DCs as well as CD8(+) T cells were necessary for the antitumor effect of intratumor AdTNF-alpha + DCs. These data demonstrate that the combination of intratumoral administration of the TNF-alpha cDNA together with naive DCs can evoke tumor suppression without systemic toxicity, providing a new paradigm for the use of TNF-alpha as antitumor therapy.