Serial Analysis of Gene Expression in Progressing and Regressing Mouse Tumors Implicates the Involvement of RANTES and TARC in Antitumor Immune Responses

Cytokine expression profiles in cervical mucus from patients with cervical cancer and its precursor lesions

Human papillomavirus (HPV) infection can persist in the cervical epithelium without provoking a strong host immune response, leading to the development of cervical cancer. Cytokines, which mediate innate and adaptive immune activities, are secreted in the cervical mucus; however, there is currently no appropriate method for assessing cytokine levels in mucus specimens. Here, we employed multiplexed bead-based immunoassays to examine cytokine levels in cervical mucus using both weighted-volume and total protein concentration methods to adjust for different specimen volumes in individual patients. Out of 18 cytokines initially examined in the primary cohort patient group (n = 28), 14 were detected in more than 10% of the samples. Of these 14 cytokines, expression levels of interferon (IFN)-γ, granulocyte-macrophage colony-stimulating factor (GM-CSF), RANTES, and eotaxin were significantly increased with the disease severity in the secondary cohort patient group (n = 235). We also examined associations between cytokine levels and clinical parameters, such as cytology and HPV genotype. Of the 14 cytokines, granulocyte colony-stimulating factor (G-CSF) was downregulated in HPV-positive specimens. Examination of co-expression patterns of cytokines in relation to HPV infection status revealed that several pairs of cytokines were simultaneously upregulated in HPV-positive cases, including INF-γ and interleukin (IL)-17A, GM-CSF and monocyte chemoattractant protein-1 (MCP-1), GM-CSF and RANTES, IL-17A and RANTES, and MCP-1 and eotaxin. Interestingly, upregulation of GM-CSF and RANTES might reflect a shift in immuno-regulatory cytokines in HPV-positive specimens, potentially associated with more severe cervical neoplasia.

The immune microenvironment: a major player in human cancers

Cancer is a major public health issue and figures among the leading causes of death in the world. Cancer development is a long process, involving the mutation, amplification or deletion of genes and chromosomal rearrangements. The transformed cells change morphologically, enlarge, become invasive and finally detach from the primary tumor to metastasize in other organs through the blood and/or lymph. During this process, the tumor cells interact with their microenvironment, which is complex and composed of stromal and immune cells that penetrate the tumor site via blood vessels and lymphoid capillaries. All subsets of immune cells can be found in tumors, but their respective density, functionality and organization vary from one type of tumor to another. Whereas inflammatory cells play a protumoral role, there is a large body of evidence of effector memory T cells controlling tumor invasion and metastasis. Thus, high densities of memory Th1/CD8 cytotoxic T cells in the primary tumors correlate with good prognosis in most tumor types. Tertiary lymphoid structures, which contain mature dendritic cells (DC) in a T cell zone, proliferating B cells and follicular DC, are found in the tumor stroma and they correlate with intratumoral Th1/CD8 T cell and B cell infiltration. Eventually, tumors undergo genetic and epigenetic modifications that allow them to escape being controlled by the immune system. This comprehensive review describes the immune contexture of human primary and metastatic tumors, how it impacts on patient outcomes and how it could be used as a predictive biomarker and guide immunotherapies.

Home sweet home: the tumor microenvironment as a haven for regulatory T cells

CD4⁺Foxp3⁺ regulatory T cells (T_regs) have a fundamental role in maintaining immune balance by preventing autoreactivity and immune-mediated pathology. However this role of T_regs extends to suppression of anti-tumor immune responses and remains a major obstacle in the development of anti-cancer vaccines and immunotherapies. This feature of T_reg activity is exacerbated by the discovery that T_reg frequencies are not only elevated in the blood of cancer patients, but are also significantly enriched within tumors in comparison to other sites. These observations have sparked off the quest to understand the processes through which T_regs become elevated in cancer-bearing hosts and to identify the specific mechanisms leading to their accumulation within the tumor microenvironment. This manuscript reviews the evidence for specific mechanisms of intra-tumoral T_reg enrichment and will discuss how this information may be utilized for the purpose of manipulating the balance of tumor-infiltrating T cells in favor of anti-tumor effector cells.

Absence of LTB4/BLT1 axis facilitates generation of mouse GM-CSF-induced long-lasting antitumor immunologic memory by enhancing innate and adaptive immune systems

BLT1 is a high-affinity receptor for leukotriene B4 (LTB4) that is a potent lipid chemoattractant for myeloid leukocytes. The role of LTB4/BLT1 axis in tumor immunology, including cytokine-based tumor vaccine, however, remains unknown. We here demonstrated that BLT1-deficient mice rejected subcutaneous tumor challenge of GM-CSF gene-transduced WEHI3B (WGM) leukemia cells (KO/WGM) and elicited robust antitumor responses against second tumor challenge with WEHI3B cells. During GM-CSF-induced tumor regression, the defective LTB4/BLT1 signaling significantly reduced tumor-infiltrating myeloid-derived suppressor cells, increased the maturation status of dendritic cells in tumor tissues, enhanced their CD4(+) T-cell stimulation capacity and migration rate of dendritic cells that had phagocytosed tumor-associated antigens into tumor-draining lymph nodes, suggesting a positive impact on GM-CSF-sensitized innate immunity. Furthermore, KO/WGM mice displayed activated adaptive immunity by attenuating regulatory CD4(+) T subsets and increasing numbers of Th17 and memory CD44(hi)CD4(+) T subsets, both of which elicited superior antitumor effects as evidenced by adoptive cell transfer. In vivo depletion assays also revealed that CD4(+) T cells were the main effectors of the persistent antitumor immunity. Our data collectively underscore a negative role of LTB4/BLT1 signaling in effective generation and maintenance of GM-CSF-induced antitumor memory CD4(+) T cells.

Biological effects of alpha particle radiation exposure on human monocytic cells

Radon ((222)Rn) gas produces decay progeny that emits high energy alpha (α)-particles. Epidemiological studies have shown that exposure to (222)Rn is linked with elevated risk of developing lung cancer, however clear mechanisms leading to such effects have not been delineated. Cytokines play a critical role in inflammation and their dysregulated production often contributes to disease pathogenesis. In this study, Bio-plex multiplex technology was employed to investigate modulations of 27 pro-inflammatory cytokines following exposure of human monocytic cells to 1.5 Gy of α-particle radiation. Concurrently, DNA damage was assessed by examining the formation of phosphorylated H2A histone family X (γ-H2AX) sites. Of the 27 cytokines assessed, 4 cytokines were shown to be statistically downregulated by ∼2 fold relative to the untreated controls and included the interleukin (IL) family of proteins (IL-2, IL-15 and IL-17) and macrophage inflammatory protein 1 beta (MIP-1b). Interferon-inducible protein-12 (IP-12), vascular endothelial growth factor and regulated on activation normal T cell expressed and secreted (RANTES) were shown to be high expressors and upregulated. Cells irradiated with α-particles ranging from 0.27 to 2.14 Gy showed statistically significant, dose-dependant increases in γ-H2AX formation. These data suggest that α-particle radiation causes dysregulation in the production of a number of pro-inflammatory cytokines and results in significant DNA damage.

Characterization of chemokines and adhesion molecules associated with T cell presence in tertiary lymphoid structures in human lung cancer

De novo formation of tertiary lymphoid structures (TLS) has been described in lung cancers. Intratumoral TLS seem to be functional and are associated with a long-term survival for lung cancer patients, suggesting that they represent an activation site for tumor-specific T cells. Here, we characterized T-cell recruitment to TLS in human lung cancer to identify the adhesion molecules and chemoattractants orchestrating this migration. We found that most TLS T cells were CD62L+ and mainly of CD4+ memory phenotype, but naive T cells were highly enriched in these structures as compared with the rest of the tumor. A specific gene expression signature associated with T cell presence was identified in TLS, which included chemokines (CCL19, CCL21, CXCL13, CCL17, CCL22, and IL16), adhesion molecules (ICAM-2, ICAM-3, VCAM-1, and MAdCAM-1) and integrins (alphaL, alpha4, and alphaD). The presence of the corresponding receptors on TLS T cells was confirmed. Intratumoral PNAd+ high endothelial venules also were exclusively associated with TLS and colocalized with CD62L+ lymphocytes. Together, these data bring new insights into the T-cell recruitment to intratumoral TLS and suggest that blood T cell enter into TLS via high endothelial venules, which represent a new gateway for T cells to the tumor. Findings identify the molecules that mediate migration of tumor-specific T cells into TLS where T cell priming occurs, suggesting new strategies to enhance the efficacy of cancer immunotherapies.

Maximal T cell-mediated antitumor responses rely upon CCR5 expression in both CD4(+) and CD8(+) T cells

Immune responses against cancer rely upon leukocyte trafficking patterns that are coordinated by chemokines. CCR5, the receptor for chemotactic chemokines MIP1alpha, MIP1beta, and RANTES (CCL3, CCL4, CCL5), exerts major regulatory effects on CD4(+)- and CD8(+) T cell-mediated immunity. Although CCR5 and its ligands participate in the response to various pathogens, its relevance to tumoral immune control has been debated. Here, we report that CCR5 has a specific, ligand-dependent role in optimizing antitumor responses. In adoptive transfer studies, efficient tumor rejection required CCR5 expression by both CD4(+) and CD8(+) T cells. CCR5 activation in CD4(+) cells resulted in CD40L upregulation, leading to full maturation of antigen-presenting cells and enhanced CD8(+) T-cell crosspriming and tumor infiltration. CCR5 reduced chemical-induced fibrosarcoma incidence and growth, but did not affect the onset or progression of spontaneous breast cancers in tolerogenic Tg(MMTV-neu) mice. However, CCR5 was required for TLR9-mediated reactivation of antineu responses in these mice. Our results indicate that CCR5 boosts T-cell responses to tumors by modulating helper-dependent CD8(+) T-cell activation.

CCL5 as an adjuvant for cancer immunotherapy

IMPORTANCE OF THE FIELD

To date cancer immunotherapy has only achieved limited clinical efficacy, thus more efficient immunotherapeutic approaches need to be explored. The CC chemokine CCL5 plays a role in chemoattraction and activation of immune cells implying its potential clinical application as an adjuvant for boosting anti-tumor immunity, although an effect on carcinogenesis and tumor cell invasiveness is also reported to be associated with CCL5.

AREAS COVERED IN THIS REVIEW

Recent progress in exploiting CCL5 as an adjuvant for cancer prevention and treatment, and updated understanding on how CCL5 is involved in tumor invasiveness and carcinogenesis.

WHAT THE READER WILL GAIN

CCL5 represents a natural adjuvant for enhancing anti-tumor immune responses. However, animal experiments and clinical reports suggest that CCL5 plays a role in carcinogenesis and invasiveness of tumor cells. Therefore, a CCL5-based cancer therapeutic approach needs to avoid the CCL5-associated potential detrimental effects.

TAKE HOME MESSAGE

CCL5 has a pre-eminent role in chemotaxis and activation of a wide spectrum of immune cells. CCL5 functions as an adjuvant to boost anti-tumor immunity by diverse protocols such as co-immunization of recombinant CCL5 protein with tumor-associated antigen, vaccination with CCL-5-expressing tumor cells, or viral vector delivery of CCL5 cDNA into growing tumor. CCL5 may also promote tumor cell survival, proliferation and invasion by different mechanisms.

Combination of intensive chemotherapy and anticancer vaccines in the treatment of human malignancies: the hematological experience

In vitro studies have demonstrated that cancer-specific T cell cytotoxicity can be induced both ex vivo and in vivo, but this therapeutic strategy should probably be used as an integrated part of a cancer treatment regimen. Initial chemotherapy should be administered to reduce the cancer cell burden and disease-induced immune defects. This could be followed by autologous stem cell transplantation that is a safe procedure including both high-dose disease-directed chemotherapy and the possibility for ex vivo enrichment of the immunocompetent graft cells. The most intensive conventional chemotherapy and stem cell transplantation are used especially in the treatment of aggressive hematologic malignancies; both strategies induce T cell defects that may last for several months but cancer-specific T cell reactivity is maintained after both procedures. Enhancement of anticancer T cell cytotoxicity is possible but posttransplant vaccination therapy should probably be combined with optimalisation of immunoregulatory networks. Such combinatory regimens should be suitable for patients with aggressive hematological malignancies and probably also for other cancer patients.

Opposing effects of toll-like receptor (TLR3) signaling in tumors can be therapeutically uncoupled to optimize the anticancer efficacy of TLR3 ligands

Many cancer cells express Toll-like receptors (TLR) that offer possible therapeutic targets. Polyadenylic-polyuridylic acid [poly(A:U)] is an agonist of the Toll-like receptor TLR3 that displays anticancer properties. In this study, we illustrate how the immunostimulatory and immunosuppressive effects of this agent can be uncoupled to therapeutic advantage. We took advantage of two TLR3-expressing tumor models that produced large amounts of CCL5 (a CCR5 ligand) and CXCL10 (a CXCR3 ligand) in response to type I IFN and poly(A:U), both in vitro and in vivo. Conventional chemotherapy or in vivo injection of poly(A:U), alone or in combination, failed to reduce tumor growth unless an immunochemotherapeutic regimen of vaccination against tumor antigens was included. CCL5 blockade improved the efficacy of immunochemotherapy, whereas CXCR3 blockade abolished its beneficial effects. These findings show how poly(A:U) can elicit production of a range of chemokines by tumor cells that reinforce immunostimulatory or immunosuppressive effects. Optimizing the anticancer effects of TLR3 agonists may require manipulating these chemokines or their receptors.

Non-transmissible Sendai virus encoding granulocyte macrophage colony-stimulating factor is a novel and potent vector system for producing autologous tumor vaccines

The recent clinical application of granulocyte macrophage colony-stimulating factor (GM-CSF)-transduced autologous tumor vaccines revealed substantial antitumor activity and valuable clinical results. However, for these vaccines to be optimally effective, the antitumor efficacies must be improved. Recently, Sendai virus (SeV) vectors, which are cytoplasmic RNA vectors, have emerged as safe vectors with high gene transduction. In the current study, the in vivo therapeutic antitumor efficacies of irradiated GM-CSF-transduced mouse renal cell carcinoma (RENCA) vaccine cells mediated by either fusion gene-deleted non-transmissible SeV encoding mouse GM-CSF (SeV/dF/G) or adenovirus (E1, E3 deleted serotype 5 adenovirus) encoding mouse GM-CSF (AdV/G) (respectively described as irRC/SeV/GM or irRC/AdV/GM) were compared in RENCA-bearing mice. The results showed that the antitumor effect was equivalent between irRC/SeV/GM and irRC/AdV/GM cells, even though the former produced less GM-CSF in vitro. The cell numbers of activated (CD80(+), CD86(+), CD80( (+) )CD86(+)) dendritic cells in lymph nodes from mice treated with irRC/AdV/GM or irRC/SeV/GM cells were increased significantly compared with those of mice treated with the respective controls, at both the earlier and later phases. In an in vitro cytotoxicity assay, splenocytes harvested from mice treated with both irRC/SeV/GM and irRC/AdV/GM cells showed tumor-specific responses against RENCA cells. The restimulated splenocytes harvested from mice treated with irRC/SeV/GM or irRC/AdV/GM cells produced significantly higher levels of interleukin-2, interleukin-4, and interferon-gamma compared with their respective controls (P < 0.05). Furthermore, vaccination with irRC/AdV/GM or irRC/SeV/GM cells induced significantly enhanced recruitment of the cytolytic effectors of CD107a(+)CD8(+) T cells and CD107a(+) natural killer cells into tumors compared with those induced by their respective controls (P < 0.05). Taken together, our results suggest that the SeV/dF/G vector is a potential candidate for the production of effective autologous GM-CSF-transduced tumor vaccines in clinical cancer immune gene therapy.

TARC and RANTES enhance antitumor immunity induced by the GM-CSF-transduced tumor vaccine in a mouse tumor model

INTRODUCTION

Transduction of the granulocyte-macrophage colony stimulating factor (GM-CSF) gene into mouse tumor cells abrogates their tumorigenicity in vivo. Our previous report demonstrated that gene transduction of GM-CSF with either TARC or RANTES chemokines suppressed in vivo tumor formation. In this paper, we examined whether the addition of either recombinant TARC or RANTES proteins to irradiated GM-CSF-transduced tumor vaccine cells enhanced antitumor immunity against established mouse tumor models to examine its future clinical application.

MATERIALS AND METHODS

Three million irradiated WEHI3B cells retrovirally transduced with murine GM-CSF cDNA in combination with either recombinant TARC or RANTES were subcutaneously inoculated into syngeneic WEHI3B-preestablished BALB/c mice.

RESULTS

Vaccinations were well tolerated. Mice treated with GM-CSF-transduced cells and the chemokines demonstrated significantly longer survival than mice treated with GM-CSF-transduced cells alone. Splenocytes harvested from mice treated with the former vaccines produced higher levels of IL-4, IL-6, IFN-gamma, and TNF-alpha, suggesting enhanced innate and adaptive immunity. Immunohistochemical analysis of tumor sections after vaccination revealed a more significant contribution of CD4+ and CD8+ T cells to tumor repression in the combined vaccine groups than controls.

CONCLUSIONS

TARC and RANTES enhance the immunological antitumor effect induced by GM-CSF in mouse WEHI3B tumor models and may be clinically useful.

Big tumor regression induced by GM-CSF gene-modified 3LL tumor cells via facilitating DC maturation and deviation toward CD11c+CD8alpha+ subset

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a powerful immune-stimulating factor that helps to generate a systemic, strong, and long-lasting immune response. However, whether the transduction of GM-CSF to tumor cell results in tumor regression and optimizes local immune microenvironment remains to be investigated. In this study, using an experimental murine tumor model, we demonstrated that the in vivo growth of 3LL tumor cells modified with the GM-CSF gene (3LL-GM) was inhibited even when the tumor diameter was over 7 mm (big tumor), and mice inoculated with GM-CSF gene-modified 3LL cells survived over 90 days, whereas mice inoculated with control parental 3LL cells and 3LL cells transduced with control vector all succumbed to the tumor by day 17 after tumor inoculation. Further analysis showed that targeted expression of GM-CSF in 3LL tumor cells markedly enhanced the systemic antitumor effect, including specific lymphocytes proliferation, cytotoxicity against 3LL tumor, and increased production of IFN-gamma. GM-CSF gene-modified 3LL cells significantly protected the mice from the parental 3LL tumor challenge. More importantly, the percentage of dendritic cells (DCs) in tumor site was greatly increased and the DCs differentiated into CD11c(+)CD8alpha(+) cells, which were reported to be able to benefit the induction of CD8(+) cytotoxic T lymphocytes (CTLs) that contribute to tumor regression. Our research indicated that GM-CSF could optimize the immune microenvironment in the tumor site, which provides a potent approach for immunotherapy of tumors.

Lung adenocarcinoma invasion in TGFbetaRII-deficient cells is mediated by CCL5/RANTES

Recently, we identified a lung adenocarcinoma signature that segregated tumors into three clades distinguished by histological invasiveness. Among the genes differentially expressed was the type II transforming growth factor-beta receptor (TGFbetaRII), which was lower in adenocarcinoma mixed subtype and solid invasive subtype tumors compared with bronchioloalveolar carcinoma. We used a tumor cell invasion system to identify the chemokine CCL5 (RANTES, regulated on activation, normal T-cell expressed and presumably secreted) as a potential downstream mediator of TGF-beta signaling important for lung adenocarcinoma invasion. We specifically hypothesized that RANTES is required for lung cancer invasion and progression in TGFbetaRII-repressed cells. We examined invasion in TGFbetaRII-deficient cells treated with two inhibitors of RANTES activity, Met-RANTES and a CCR5 receptor-blocking antibody. Both treatments blocked invasion induced by TGFbetaRII knockdown. In addition, we examined the clinical relevance of the RANTES-CCR5 pathway by establishing an association of RANTES and CCR5 immunostaining with invasion and outcome in human lung adenocarcinoma specimens. Moderate or high expression of both RANTES and CCR5 was associated with an increased risk for death, P=0.014 and 0.002, respectively. In conclusion, our studies indicate RANTES signaling is required for invasion in TGFbetaRII-deficient cells and suggest a role for CCR5 inhibition in lung adenocarcinoma prevention and treatment.

Gene therapy with CX3CL1/Fractalkine induces antitumor immunity to regress effectively mouse hepatocellular carcinoma

CX3CL1/Fractalkine(FK), a chemokine existing in both secreted and membrane anchored form, was reported to induce suppressive activities in tumor models. Here, we demonstrate for the first time the antitumor effects of FK in murine hepatocellular carcinoma (HCC) by constructing a FK eukaryotic expression vector (pIRES-FK) and transferring it into such tumor cells. Tumor rejection experiments were performed by injecting FK gene-modified murine HCC cell line (MM45T.Li) into immunocompetent mice, which significantly inhibited tumorigenicity or growth of MM45T.Li-FK cells. Immunohistochemistry examination and fluorescence-activated cell sorting analyses revealed both CD4+ and CD8+ T cells infiltration within the tumor together with a marked increase of these cells in the peripheral blood. Splenic lymphocyte from mice treated with MM45T.Li-FK were effective in the induction of tumor-specific cytotoxic T cells. We also observed an increased production of IL-2 and IFN-gamma in MM45T.Li-FK tumor tissue. Our results suggest that transfer of the FK gene into tumor cells could elicit a specific antitumor immunity capable of inhibiting tumor growth which lead to increased survival of tumor-bearing hosts. FK should be considered as a chemokine suitable for cancer immunoprevention or gene therapy.