Synergistic effect of lymphotactin and interferon gamma-inducible protein-10 transgene expression in T-cell localization and adoptive T-cell therapy of tumors

The use of RNA-based treatments in the field of cancer immunotherapy

Over the past several decades, mRNA vaccines have evolved from a theoretical concept to a clinical reality. These vaccines offer several advantages over traditional vaccine techniques, including their high potency, rapid development, low-cost manufacturing, and safe administration. However, until recently, concerns over the instability and inefficient distribution of mRNA in vivo have limited their utility. Fortunately, recent technological advancements have mostly resolved these concerns, resulting in the development of numerous mRNA vaccination platforms for infectious diseases and various types of cancer. These platforms have shown promising outcomes in both animal models and humans. This study highlights the potential of mRNA vaccines as a promising alternative approach to conventional vaccine techniques and cancer treatment. This review article aims to provide a thorough and detailed examination of mRNA vaccines, including their mechanisms of action and potential applications in cancer immunotherapy. Additionally, the article will analyze the current state of mRNA vaccine technology and highlight future directions for the development and implementation of this promising vaccine platform as a mainstream therapeutic option. The review will also discuss potential challenges and limitations of mRNA vaccines, such as their stability and in vivo distribution, and suggest ways to overcome these issues. By providing a comprehensive overview and critical analysis of mRNA vaccines, this review aims to contribute to the advancement of this innovative approach to cancer treatment.

PSMA-homing dsRNA chimeric protein vector kills prostate cancer cells and activates anti-tumor bystander responses

The treatment of metastatic androgen-resistant prostate cancer remains a challenge. We describe a protein vector that selectively delivers synthetic dsRNA, polyinosinic/polycytidylic acid (polyIC), to prostate tumors by targeting prostate specific membrane antigen (PSMA), which is overexpressed on the surface of prostate cancer cells.

The chimeric protein is built from the double stranded RNA (dsRNA) binding domain of PKR tethered to a single chain anti-PSMA antibody. When complexed with polyIC, the chimera demonstrates selective and efficient killing of prostate cancer cells. The treatment causes the targeted cancer cells to undergo apoptosis and to secrete toxic cytokines. In a bystander effect, these cytokines kill neighboring cancer cells that do not necessarily overexpress PSMA, and activate immune cells that enhance the killing effect. The strong effects of the targeted polyIC are demonstrated on both 2D cell cultures and 3D tumor spheroids.

Optimizing Tumor Microenvironment for Cancer Immunotherapy: β-Glucan-Based Nanoparticles

Immunotherapy is revolutionizing cancer treatment. Recent clinical success with immune checkpoint inhibitors, chimeric antigen receptor T-cell therapy, and adoptive immune cellular therapies has generated excitement and new hopes for patients and investigators. However, clinically efficacious responses to cancer immunotherapy occur only in a minority of patients. One reason is the tumor microenvironment (TME), which potently inhibits the generation and delivery of optimal antitumor immune responses. As our understanding of TME continues to grow, strategies are being developed to change the TME toward one that augments the emergence of strong antitumor immunity. These strategies include eliminating tumor bulk to provoke the release of tumor antigens, using adjuvants to enhance antigen-presenting cell function, and employ agents that enhance immune cell effector activity. This article reviews the development of β-glucan and β-glucan-based nanoparticles as immune modulators of TME, as well as their potential benefit and future therapeutic applications. Cell-wall β-glucans from natural sources including plant, fungi, and bacteria are molecules that adopt pathogen-associated molecular pattern (PAMP) known to target specific receptors on immune cell subsets. Emerging data suggest that the TME can be actively manipulated by β-glucans and their related nanoparticles. In this review, we discuss the mechanisms of conditioning TME using β-glucan and β-glucan-based nanoparticles, and how this strategy enables future design of optimal combination cancer immunotherapies.

PSMA-targeted polyinosine/polycytosine vector induces prostate tumor regression and invokes an antitumor immune response in mice

There is an urgent need for an effective treatment for metastatic prostate cancer (PC). Prostate tumors invariably overexpress prostate surface membrane antigen (PSMA). We designed a nonviral vector, PEI-PEG-DUPA (PPD), comprising polyethylenimine-polyethyleneglycol (PEI-PEG) tethered to the PSMA ligand, 2-[3-(1, 3-dicarboxy propyl)ureido] pentanedioic acid (DUPA), to treat PC. The purpose of PEI is to bind polyinosinic/polycytosinic acid (polyIC) and allow endosomal release, while DUPA targets PC cells. PolyIC activates multiple pathways that lead to tumor cell death and to the activation of bystander effects that harness the immune system against the tumor, attacking nontargeted neighboring tumor cells and reducing the probability of acquired resistance and disease recurrence. Targeting polyIC directly to tumor cells avoids the toxicity associated with systemic delivery. PPD selectively delivered polyIC into PSMA-overexpressing PC cells, inducing apoptosis, cytokine secretion, and the recruitment of human peripheral blood mononuclear cells (PBMCs). PSMA-overexpressing tumors in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with partially reconstituted immune systems were significantly shrunken following PPD/polyIC treatment, in all cases. Half of the tumors showed complete regression. PPD/polyIC invokes antitumor immunity, but unlike many immunotherapies does not need to be personalized for each patient. The potent antitumor effects of PPD/polyIC should spur its development for clinical use.

CXCL10/XCL1 fusokine elicits in vitro and in vivo chemotaxis

Fusokines are proteins formed by the fusion of two cytokines. They have greater bioavailability and therapeutic potential than individual cytokines or a combination of different cytokines. Interferon-gamma-inducible protein 10 (CXCL10) and lymphotactin (XCL1) are members of the chemotactic family of cytokines, which induce tumor regression by eliciting immune-system cell chemotaxis. We engineered a replication-deficient adenoviral system expressing CXCL10/XCL1 fusokine (Ad FIL) and assessed its chemotactic response in vitro and in vivo. The CXCL10/XCL1 fusokine elicited a greater chemotactic effect in IL-2 stimulated lymphocytes than individual or combined cytokines in vitro. CXCL10/XCL1 fusokine biological activity was demonstrated in vivo by intratumoral chemoattraction of CXCR3+ cells. Thus, this novel CXCL10/XCL1 fusokine may represent a potential tool for gene therapy treatment of cancer and other illnesses that require triggering immune-system cell recruitment.

Immune modulation of the tumor microenvironment for enhancing cancer immunotherapy

There is much promise in the use of immunotherapy for the treatment of cancer. Approaches such as those using antibodies or adoptive cell transfer can mediate complete tumor regression in a proportion of patients. However, the tumor microenvironment can inhibit immune responses leading to ineffective or suboptimal responses of tumors to immunotherapy in the majority of cases. As our knowledge of the tumor microenvironment increases, many strategies are emerging for changing the immunosuppressive nature of the tumor toward a microenvironment able to support immunity. These strategies aim to enhance the ability of immunotherapies to initiate effective immune responses able to destroy tumors. In this article, we review approaches that use immunomodulators specifically to modify the tumor microenvironment, and their use in combination with other immune-based strategies for cancer therapy.

Chemokine-based immunotherapy: delivery systems and combination therapies

A major role of chemokines is to mediate leukocyte migration through interaction with G-protein-coupled receptors. Various delivery systems have been developed to utilize the chemokine properties for combating disease. Viral and mutant viral vectors expressing chemokines, genetically modified dendritic cells with chemokine or chemokine receptors, engineered chemokine-expressing tumor cells and pDNA encoding chemokines are among these methods. Another approach for inducing a targeted immune response is fusion of a targeting antibody or antibody fragment to a chemokine. In addition, chemokines induce more effective antitumor immunity when used as adjuvants. In this regard, chemokines are codelivered along with antigens or fused as a targeting unit with antigenic moieties. In this review, several chemokines with their role in inducing immune response against different diseases are discussed, with a major emphasis on cancer.

EGFR-homing dsRNA activates cancer-targeted immune response and eliminates disseminated EGFR-overexpressing tumors in mice

PURPOSE

The cause of most cancer deaths is incurable dissemination of cancer cells into vital organs. Current systemic therapies for disseminated cancers provide limited efficacy and are often accompanied by toxic side effects. We have recently shown that local application of epidermal growth factor receptor (EGFR)-targeted polyinosine-cytosine (polyIC) eradicates preestablished EGFR-overexpressing tumors. Here we show for the first time the high efficiency of systemic application of polyIC/melittin-polyethyleneimine-polyethyleneglycol-EGF (polyIC/MPPE) in combination with human immune cells.

EXPERIMENTAL DESIGN

Cancer-targeted activation of immune cells was examined in vitro and in vivo following transfection with polyIC/MPPE. The therapeutic efficiency of the strategy was then examined on disseminated EGFR-overexpressing tumors grown in severe combined immunodeficient (SCID) mice.

RESULTS

Intravenous delivery of polyIC/MPPE followed by intraperitoneal injection of peripheral blood mononuclear cells induced the complete cure of SCID mice with preestablished disseminated EGFR-overexpressing tumors, with no adverse toxic effects. The immune cells and the cytokines they produce are localized to the tumor site of the treated animal and contribute decisively to the demise of the tumor cells. The immune system homes to the tumors, due to the chemokines produced by the internalized polyIC.

CONCLUSION

The EGFR-homing vector loaded with polyIC can be used to treat and possibly cure patients with disseminated EGFR-overexpressing tumors. The possibility of adopting this strategy to treat other tumors that express a protein capable of ligand induced internalization is discussed.

CD4+ Th-APC with acquired peptide/MHC class I and II complexes stimulate type 1 helper CD4+ and central memory CD8+ T cell responses

T cell-T cell Ag presentation is increasingly attracting attention. We previously showed that the in vitro OVA-pulsed dendritic cell (DC(OVA))-activated CD4(+) Th cells acquired OVA peptide/MHC (pMHC) class I and costimulatory molecules such as CD54 and CD80 from DC(OVA) and acted as CD4(+) Th-APC capable of stimulating OVA-specific CD8(+) CTL responses. In this study, we further applied the OVA-specific TCR-transgenic OT I and OT II mice with deficiency of various cytokines or costimulatory molecule genes useful for studying the molecular mechanisms underlying in Th-APC's stimulatory effect. We demonstrated that DC(OVA)-stimulated OT II CD4(+) Th-APC also acquired costimulatory molecules such as CD40, OX40L, and 4-1BBL and the functional pMHC II complexes by DC(OVA) activation. CD4(+) Th-APC with acquired pMHC II and I were capable of stimulating CD4(+) Th1 and central memory CD8(+)44(+)CD62L(high)IL-7R(+) T cell responses leading to antitumor immunity against OVA-expressing mouse B16 melanoma. Their stimulatory effect on CD8(+) CTL responses and antitumor immunity is mediated by IL-2 secretion, CD40L, and CD80 signaling and is specifically targeted to CD8(+) T cells in vivo via acquired pMHC I. In addition, CD4(+) Th-APC expressing OVA-specific TCR, FasL, and perforin were able to kill DC(OVA) and neighboring Th-APC expressing endogenous and acquired pMHC II. Taken together, we show that CD4(+) Th-APC can modulate immune responses by stimulating CD4(+) Th1 and central memory CD8(+) T cell responses and eliminating DC(OVA) and neighboring Th-APC. Therefore, our findings may have great impacts in not only the antitumor immunity, but also the regulatory T cell-dependent immune tolerance in vivo.

Chemokine–chemokine receptors in cancer immunotherapy

A surge in interest in the chemokine–chemokine receptor network is probably related to the expanding roles that chemokines have now been identified to play in human biology, particularly immunity. Specific tissue microenvironments express distinct chemokines and both hematopoietic and nonhematopoietic cells have receptor expression profiles that permit the coordinated trafficking and organization of cells within these specific tissues. Since the chemokine network plays critical roles in both the function of the immune system and the progression of cancer, it is an attractive target for therapeutic manipulation. This review will focus on chemokine and chemokine receptor network-related therapeutic interventions that utilize host–tumor interactions particularly involving the immune system.

XCL1 enhances regulatory activities of CD4+ CD25(high) CD127(low/-) T cells in human allergic asthma

Chemokine-mediated recruitment of regulatory cell subsets to the airway during inflammation and enhancement of their activities are potential strategies for therapeutic development in allergic asthma (AA). In this study, we aim to explore the role of XCL1, a chemokine associated with immune suppression and allergy, on CD4(+)CD25(high)CD127(low/-) regulatory T cell (Treg) function in AA. Flow cytometry and PCR analysis showed a reduction in XCL1 and XCR1 expression in AA Treg compared with healthy control and nonallergic asthmatic counterparts. This reduction in XCL1 expression was associated with the suboptimal regulatory function of Treg in AA. Interestingly, incubation with recombinant human XCL1 significantly increased Treg-mediated suppression and cytotoxicity by up-regulating expression of XCL1 and chief effector molecules of Treg function. Altogether, these results suggest an association between dysregulated XCL1 expression and reduced Treg activities in AA, as well as a potential role of XCL1 in reversing defective Treg function in the disease.

Transforming growth factor-beta receptor blockade augments the effectiveness of adoptive T-cell therapy of established solid cancers

PURPOSE

Adoptive cellular immunotherapy is a promising 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-beta (TGF-beta) 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-beta signaling combined with adoptive T-cell transfer would enhance the effectiveness of the therapy.

EXPERIMENTAL DESIGN

Flank tumors were generated in mice using the chicken ovalbumin-expressing thymoma cell line, EG7. Splenocytes from transgenic OT-1 mice (whose CD8 T cells recognize an immunodominant peptide in chicken ovalbumin) were activated in vitro and adoptively transferred into mice bearing large tumors in the presence or absence of an orally available TGF-beta receptor-I kinase blocker (SM16).

RESULTS

We observed markedly smaller tumors in the group receiving the combination of SM16 chow and adoptive transfer. Additional investigation revealed that TGF-beta 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 tumor necrosis factor-alpha and decrease in arginase mRNA expression.

CONCLUSIONS

We found that systemic blockade of TGF-beta receptor activity augmented the antitumor activity of adoptively transferred T cells and may thus be a useful adjunct in future clinical trials.

In situ expression of IFN-gamma-inducible T cell alpha chemoattractant in breast cancer mounts an enhanced specific anti-tumor immunity which leads to tumor regression

Increased evidence indicates that chemokines are involved in tumor growth. ITAC, a key member of chemokines, possesses the ability to recruit T cells and enhance immune responses. Therefore, ITAC might contribute to antitumor immunity. In this study, we evaluated the relationship between the expression of ITAC and human breast cancer advancement. We further investigated whether forced expression of ITAC in tumor sites could mediate enhanced antitumor immunity in a murine breast cancer model. Results showed that ITAC expression level was down-regulated in 31 breast cancer specimens compared to normal mammary tissues, and associated negatively with the stages of breast cancer. Contrarily, forced expression of ITAC in murine 4T1 tumor cells resulted in tumor regression after initial growth upon injection into naïve Balb/c mice. More lymphocytes were recruited to the site of tumor inoculated by 4T1-ITAC and more than 80% of these T cells expressed the ITAC receptor, CXCR3. ITAC-recruited TILs exhibited 4T1-specific proliferation and cytotoxicity, and an increased IFN-gamma but decreased IL-4 production. Importantly, forced expression of ITAC in 4T1 tumor nodules inhibited tumor growth. These findings demonstrated that the decreased expression of ITAC is associated with the advancement of breast cancer in patients. Forced expression of ITAC in tumor site not only induces increased T cell-recruitment and elicits a specific antitumor immunity, but also mediates regression of established 4T1 tumors, indicating the potential application of ITAC-expressing tumor cells in cancer immunotherapy and vaccine designing.

Tumor-Derived Chemokine MCP-1/CCL2 Is Sufficient for Mediating Tumor Tropism of Adoptively Transferred T Cells

To exert a therapeutic effect, adoptively transferred tumor-specific CTLs must traffic to sites of tumor burden, exit the circulation, and infiltrate the tumor microenvironment. In this study, we examine the ability of adoptively transferred human CTL to traffic to tumors with disparate chemokine secretion profiles independent of tumor Ag recognition. Using a combination of in vivo tumor tropism studies and in vitro biophotonic chemotaxis assays, we observed that cell lines derived from glioma, medulloblastoma, and renal cell carcinoma efficiently chemoattracted ex vivo-expanded primary human T cells. We compared the chemokines secreted by tumor cell lines with high chemotactic activity with those that failed to elicit T cell chemotaxis (Daudi lymphoma, 10HTB neuroblastoma, and A2058 melanoma cells) and found a correlation between tumor-derived production of MCP-1/CCL2 (> or =10 ng/ml) and T cell chemotaxis. Chemokine immunodepletion studies confirmed that tumor-derived MCP-1 elicits effector T cell chemotaxis. Moreover, MCP-1 is sufficient for in vivo T cell tumor tropism as evidenced by the selective accumulation of i.v. administered firefly luciferase-expressing T cells in intracerebral xenografts of tumor transfectants secreting MCP-1. These studies suggest that the capacity of adoptively transferred T cells to home to tumors may be, in part, dictated by the species and amounts of tumor-derived chemokines, in particular MCP-1.

Antitumor effects of the MIG and IP-10 genes transferred with poly [D,L-2,4-diaminobutyric acid] on murine neuroblastoma

The number of tumor-infiltrating lymphocytes is known to be related to outcomes in patients with a variety of malignancies. Interferon (IFN) gamma-inducible protein-10 (IP-10) and monokine induced by IFNgamma (MIG) have chemotactic effects on activated T lymphocytes and natural killer (NK) cells. The aim of this study was to evaluate the antitumor effects of exogenous expression of the MIG and IP-10 genes delivered to solid tumors by poly [D,L-2,4-diaminobutyric acid] (PDBA). The murine MIG and IP-10 genes were transfected into mouse neuroblastoma cells with PDBA. MIG and IP-10 levels in supernatants of transfected cells were measured by enzyme-linked immunosorbent assay. The chemotactic activities of MIG and IP-10 in the supernatants of cell cultures were measured by chemotaxis assay. Tumors were injected in vivo with PDBA/pmMIGColon, two colonsIP-10 complexes to evaluate the effects of these genes on tumor volume and survival time of mice. Transfected PDBA/pmMIGColon, two colonsIP-10 complexes produced MIG and IP-10 protein in vitro. MIG and IP-10 proteins secreted into the culture medium showed chemotactic activity. MIG and IP-10 gene therapy with the PDBA system in vivo significantly inhibited tumor growth and prolonged survival time of mice. In conclusion, PDBA-mediated MIG and IP-10 gene therapy may be useful for treatment of solid tumors.

Targeted in vivo expression of IFN-gamma-inducible protein 10 induces specific antitumor activity

Although it is known that the chemoattractant effect of IFN-gamma inducible protein 10 (IP-10), a CXC chemokine (CXCL10), plays an important role in T cell-mediated antitumor immunity in vivo, whether IP-10 is involved in modulating the proliferation, survival and functional activation of tumor-specific T cells remains poorly investigated. Using an experimental mouse tumor model, we demonstrated that the in vivo growth of 4T1 tumor cells harboring IP-10 gene (4T1-IP-10) was inhibited. Mice inoculated with 4T1-IP-10 tumor cells expressing functional IP-10 survived over 90 days, whereas mice injected with control parental 4T1 cells and mice of control 4T1 cells transduced with control plasmid all succumbed to the tumor by day 38 after tumor inoculation. Mechanical analysis showed that targeted expression of IP-10 in 4T1 tumor cells markedly enhanced the infiltration of tumor-specific T cells into the 4T1-IP-10 tumor. These tumor infiltrating T lymphocytes (TILs) recruited by IP-10 were potent cytolytic killers against 4T1 tumor cells and were able to proliferate and produce high levels of IFN-gamma in response to 4T1 cells. In vivo administration of IP-10-recruited TILs induced vigorous proliferation of these TILs in situ in the 4T1-IP-10 tumor but not in the 4T1-pcDNA3 and parental 4T1 tumors. Furthermore, culture of TILs together with recombinant IP-10 significantly enhanced the proliferation and expansion of IP-10-recruited TILs in response to 4T1 tumor antigens. These results suggest that IP-10 is not only able to chemoattract tumor-specific T cells into the local tissue, but also enhance the proliferation, survival, and functional activation of these TILs, leading to the tumor regression. Thus, targeted expression of IP-10 in vivo will allow for the development of a novel approach for immunotherapy of tumor.

CXCR3/CXCR3 ligand biological axis impairs RENCA tumor growth by a mechanism of immunoangiostasis

Metastatic renal cell carcinoma (RCC) responds poorly to chemo- or radiation therapy but appears to respond to systemic immunotherapy (i.e., IL-2 and/or IFN-alpha), albeit with only 5-10% durable response. The CXCR3/CXCR3 ligand biological axis plays an important role in mediating type 1 cytokine-dependent cell-mediated immunity, which could be beneficial for attenuating RCC if optimized. We found that systemic IL-2 induced the expression of CXCR3 on circulating mononuclear cells but impaired the CXCR3 ligand chemotactic gradient from plasma to tumor by increasing circulating CXCR3 ligand levels in a murine model of RCC. Moreover, the antitumor effect of systemic IL-2 was CXCR3-dependent, as IL-2 failed to inhibit tumor growth and angiogenesis in CXCR3-/- mice. We hypothesized that the immunotherapeutic effect of the CXCR3/CXCR3 ligand biological axis could be optimized by first priming with systemic IL-2 to induce CXCR3 expression on circulating mononuclear cells followed by enhancing the intratumor CXCR3 ligand levels to establish optimal CXCR3-dependent chemotactic gradient. We found that combined systemic IL-2 with an intratumor CXCR3 ligand (CXCL9) lead to significantly greater reduction in tumor growth and angiogenesis, increased tumor necrosis, and increased intratumor infiltration of CXCR3+ mononuclear cells, as compared with either IL-2 or CXCL9 alone. The enhanced antitumor effect of the combined strategy was associated with a more optimized CXCR3-dependent chemotactic gradient and increased tumor-specific immune response. These data suggest that the combined strategy of systemic IL-2 with intratumor CXCR3 ligand is more efficacious than either strategy alone for reducing tumor-associated angiogenesis and augmenting tumor-associated immunity, the concept of immunoangiostasis.

Murine B16 Melanomas Expressing High Levels of the Chemokine Stromal-Derived Factor-1/CXCL12 Induce Tumor-Specific T Cell Chemorepulsion and Escape from Immune Control

The chemokine, stromal-derived factor-1/CXCL12, is expressed by normal and neoplastic tissues and is involved in tumor growth, metastasis, and modulation of tumor immunity. T cell-mediated tumor immunity depends on the migration and colocalization of CTL with tumor cells, a process regulated by chemokines and adhesion molecules. It has been demonstrated that T cells are repelled by high concentrations of the chemokine CXCL12 via a concentration-dependent and CXCR4 receptor-mediated mechanism, termed chemorepulsion or fugetaxis. We proposed that repulsion of tumor Ag-specific T cells from a tumor expressing high levels of CXCL12 allows the tumor to evade immune control. Murine B16/OVA melanoma cells (H2b) were engineered to constitutively express CXCL12. Immunization of C57BL/6 mice with B16/OVA cells lead to destruction of B16/OVA tumors expressing no or low levels of CXCL12 but not tumors expressing high levels of the chemokine. Early recruitment of adoptively transferred OVA-specific CTL into B16/OVA tumors expressing high levels of CXCL12 was significantly reduced in comparison to B16/OVA tumors, and this reduction was reversed when tumor-specific CTLs were pretreated with the specific CXCR4 antagonist, AMD3100. Memory OVA-specific CD8+ T cells demonstrated antitumor activity against B16/OVA tumors but not B16/OVA.CXCL12-high tumors. Expression of high levels of CXCL12 by B16/OVA cells significantly reduced CTL colocalization with and killing of target cells in vitro in a CXCR4-dependent manner. The repulsion of tumor Ag-specific T cells away from melanomas expressing CXCL12 confirms the chemorepellent activity of high concentrations of CXCL12 and may represent a novel mechanism by which certain tumors evade the immune system.

Anti-tumor responses induced by chemokine CCL19 transfected into an ovarian carcinoma model via fiber-mutant adenovirus vector

Considerable attention has recently been paid to the application of chemokines to cancer immunotherapy because of their chemotactic affinity for a variety of immune cells and because several chemokines are strongly angiostatic. In the present study, the recombinant adenovirus vectors encoding chemokine CCL19 or XCL1 in an E1 cassette (AdRGD-mCCL19 and AdRGD-mXCL1) were developed. The constructed fiber-mutant adenovirus vector, which contained the integrin-targeting Arg-Gly-Asp (RGD) sequence in the fiber knob, notably enhanced the transfection efficiency to OV-HM ovarian carcinoma cells compared to that induced by conventional adenovirus vector. The results of an in vitro chemotaxis assay for chemokine-encoding vector demonstrated that both AdRGD-mCCL19 and AdRGD-mXCL1 could induce the migration of cells expressing specific chemokine receptors. Of the two chemokine-encoding vectors evaluated in vivo, AdRGD-mCCL19 showed significant tumor-suppressive activity in B6C3F1 mice via transduction into OV-HM cells, whereas XCL1 did not exhibit any notable anti-tumor effects, suggesting that CCL19 may be a candidate for cancer immunotherapy.

EGF receptor-targeted synthetic double-stranded RNA eliminates glioblastoma, breast cancer, and adenocarcinoma tumors in mice

BACKGROUND

Glioblastoma multiforme (GBM) is the most lethal form of brain cancer. With the available treatments, survival does not exceed 12-14 mo from the time of diagnosis. We describe a novel strategy to selectively induce the death of glioblastoma cells and other cancer cells that over-express the EGF receptor. Using a non-viral delivery vector that homes to the EGF receptor, we target synthetic anti-proliferative dsRNA (polyinosine-cytosine [poly IC]), a strong activator of apoptosis, selectively to cancer cells.

METHODS AND FINDINGS

Poly IC was delivered by means of a non-viral vector: 25kDa polyethylenimine-polyethyleneglycol-EGF (PEI25-PEG-EGF). EGFR-targeted poly IC induced rapid apoptosis in the target cells in vitro and in vivo. Expression of several cytokines and "bystander killing" of untransfected tumor cells was detected in vitro and in vivo. Intra-tumoral delivery of the EGFR-targeted poly IC induced the complete regression of pre-established intracranial tumors in nude mice, with no obvious adverse toxic effects on normal brain tissue. A year after treatment completion the treated mice remain cancer-free and healthy. Similarly, non-viral delivery of poly IC completely eliminated pre-established breast cancer and adenocarcinoma xenografts derived from EGFR over-expressing cancer cell lines, suggesting that the strategy is applicable to other EGFR-over-expressing tumors.

CONCLUSION

The strategy described has yielded an effective treatment of EGFR over-expressing GBM in an animal model. If this strategy is translated successfully to the clinical setting, it may actually offer help to GBM patients. Moreover the elimination of two additional EGFR over-expressing cancers in vivo suggests that in principle this strategy can be applied to treat other tumors that over-express EGFR.

Synergy in cytokine and chemokine networks amplifies the inflammatory response

The inflammatory response is a highly co-ordinated process involving multiple factors acting in a complex network as stimulators or inhibitors. Upon infection, the sequential release of exogenous agents (e.g. bacterial and viral products) and induction of endogenous mediators (e.g. cytokines and chemokines) contribute to the recruitment of circulating leukocytes to the inflamed tissue. Microbial products trigger multiple cell types to release cytokines, which in turn are potent inducers of chemokines. Primary cytokines act as endogenous activators of the immune response, whereas inducible chemokines act as secondary mediators to attract leukocytes. Interaction between exogenous and endogenous mediators thus enhances the inflammatory response. In this review, the synergistic interaction between cytokines to induce chemokine production and the molecular mechanisms of the cooperation amongst co-induced chemokines to further increase leukocyte recruitment to the site of inflammation are discussed.

Gene modification strategies to induce tumor immunity

The immune system provides an attractive option for use in cancer therapy. Our increasing understanding of the molecular events important in the generation of an effective immune response presents us with the opportunity to manipulate key genes to boost the immune response against cancer. Genetic modification is being employed to enhance a range of immune processes including antigen presentation, activation of specific T cells, and localization of immune effectors to tumors. In this review, we describe how many diverse cell types, including dendritic cells, T cells, and tumor cells, are being modified with a variety of genes, including those encoding antigens, cytokines, and chemokines, in order to enhance tumor immunity.

Expression of the interferon-inducible chemokine IP-10 (CXCL10), a chemokine with proposed anti-neoplastic functions, in Hodgkin lymphoma and nasopharyngeal carcinoma

Hodgkin lymphoma (HL) and nasopharyngeal carcinoma (NPC) are characterized by their association with Epstein-Barr virus (EBV) and an abundant infiltrate of reactive lymphoid cells. The presence of this lymphoid stroma may influence the effect of anti-viral immunotherapy. The interferon-inducible chemokine IP-10 has anti-neoplastic effects in several model systems mediated by T-cells expressing the CXCR3 chemokine receptor. Using in situ hybridization, it is shown that IP-10 is expressed in neoplastic cells of HL and correlates both with the mixed cellularity histotype and with EBV infection. IP-10 expression was also detected in tumour cells of most NPCs as well as in EBV-negative squamous cell carcinomas of the tongue. Thus, in carcinomas, IP-10 expression showed no correlation with EBV infection. Numerous CXCR3-positive lymphocytes were detected in the lymphoid stroma of HL and NPC, raising the possibility of a Th1-predominant immune response in these cases. In view of the proposed anti-neoplastic functions of IP-10 and CXCR3-positive lymphocytes, these findings are unexpected and raise the possibility that endogenous IP-10 expression in the context of human tumours may not exert the anti-tumour effects ascribed to it by in vitro experiments.