Carcinogen-induced Fibrosarcoma Research Articles

A distinct chemokine axis does not account for enrichment of Foxp3(+) CD4(+) T cells in carcinogen-induced fibrosarcomas.

The frequency of CD4+ Foxp3+ regulatory T (Treg) cells is often significantly increased in the blood of tumour-bearing mice and people with cancer. Moreover, Treg cell frequencies are often higher in tumours compared with blood and lymphoid organs. We wished to determine whether certain chemokines expressed within the tumour mass selectively recruit Treg cells, thereby contributing to their enrichment within the tumour-infiltrating lymphocyte pool. To achieve this goal, the chemokine profile of carcinogen-induced fibrosarcomas was determined, and the chemokine receptor expression profiles of both CD4+ Foxp3− and CD4+ Foxp3+ T cells were compared. These analyses revealed that the tumours are characterized by expression of inflammatory chemokines (CCL2, CCL5, CCL7, CCL8, CCL12, CXCL9, CXCL10 and CX3CL1), reflected by an enrichment of activated Foxp3− and Foxp3+ T cells expressing T helper type 1-associated chemokine receptors. Notably, we found that CXCR3+ T cells were significantly enriched in the tumours although curiously we found no evidence that CXCR3 was required for their recruitment. Instead, CXCR3 marks a population of activated Foxp3− and Foxp3+ T cells, which use multiple and overlapping ligand receptor pairs to guide their migration to tumours. Collectively, these data indicate that enrichment of Foxp3+ cells in tumours characterized by expression of inflammatory chemokines, does not occur via a distinct chemokine axis, thus selective chemokine blockade is unlikely to represent a meaningful therapeutic strategy for preventing Treg cell accumulation in tumours.

Progression of carcinogen-induced fibrosarcomas is associated with the accumulation of naïve CD4+ T cells via blood vessels and lymphatics.

What's new?It is well known that a tumors' microenvironment can impair the anti‐tumor immune response. The culprits are usually assumed to be various suppressor cells and cytokines. In this study, however, the authors found that seemingly innocuous, naïve T cells may also play a significant role—simply by accumulating and possibly out‐competing activated effector cells within the tumor. A better understanding of the signals produced by the tumor microenvironment may allow researchers to alter this T‐cell pool, thus enhancing the immune response.

Interleukin-27 Signaling Promotes Immunity against Endogenously Arising Murine Tumors

Interleukin-27 (IL-27) is a pleiotropic cytokine but its immunosuppressive effects predominate during many in vivo immunological challenges. Despite this, evidence from tumor cell line transfer models suggested that IL-27 could promote immune responses in the tumor context. However, the role of IL-27 in immunity against tumors that develop in situ and in tumor immunosurveillance remain undefined. In this study, we demonstrate that tumor development and growth are accelerated in IL-27 receptor α (Il27ra)-deficient mice. Enhanced tumor growth in both carcinogen-induced fibrosarcoma and oncogene-driven mammary carcinoma was associated with decreased interferon-γ production by CD4 and CD8 T cells and increased numbers of regulatory T-cells (Treg). This is the first study to show that IL-27 promotes protective immune responses against endogenous tumors, which is critical as the basis for future development of an IL-27 based therapeutic agent.

P063 Interleukin-27 signaling promotes immunity against endogenously arising tumors

Interleukin-27 (IL-27) is a pleiotropic cytokine but it’s immunosuppressive effects predominate during many in vivo immunological challenges. Despite this, evidence from tumor cell line transfer models suggested that IL-27 could promote immune responses in the tumor context. However, the role of IL-27 in immunity against tumors that develop in situ and in tumor immunosurveillance remains undefined. In this study, we use IL-27 receptor a (Il27ra) -deficient mice to examine the effect of physiological IL-27 in the context of anti-tumor responses. Carcinogen-induced fibrosarcoma and polyoma middle T antigen oncogene-driven mammary carcinomas are used as autochtonous tumor models. Associated changes in the immune response were examined by histology and flow cytometry. In this study, we demonstrate that tumor development and growth are accelerated in IL-27 receptor a (Il27ra) -deficient mice, using models of carcinogen-induced fibrosarcoma and polyoma middle T antigen oncogene-driven mammary carcinomas. Enhanced tumor growth was associated with decreased interferon-g production and increased number of regulatory T-cells (T reg ). This is the first study to show that IL-27 promotes protective immune responses against endogenous tumors, which is critical as the basis for future development of an IL-27 based therapeutic agent.

Proliferative response of T cells from tumor-immune chickens to carcinogen-induced fibrosarcoma cells

Immunity to carcinogen-induced transplantable fibrosarcomas (CHCT-NYU-4, -97, -36 and -20) in SC chickens was studied by the ability of spleen cells from NYU-4 or -97 immune chickens to proliferate in response to tumor cells in vitro. Spleen, but not peripheral blood cells, from NYU-4 immune chickens proliferated significantly more vigorously to gamma-irradiated NYU-4 cells than did cells from normal chickens. The proliferative response was not much affected by addition of indomethacin. Spleen cells from NYU-4-immune agammaglobulinemic (A gamma) chickens exhibit the same ability to proliferate in presence of gamma-irradiated NYU-4 tumor cells. Analysis of the phenotype of the T-cell component involved in proliferation showed that the proliferative response was significantly decreased by removal of CT4+ cells through indirect panning. Removal of CT8+ cells enhanced background proliferation without affecting the total thymidine incorporation in the presence of tumor cells. Immune spleen cells usually gave highest responses to the immunizing tumor, but also exhibited cross-reactivity to cells from other individual tumors induced by the same carcinogen.

Quantifying adductive modification of hemoglobin from mice exposed to benzo[ a]pyrene

The present work describes a method for the detection of minute amounts of benzo[ a]pyrene, as the diolepoxide metabolite, bound covalently to the hemoglobin of erythrocytes isolated from mice previously exposed to the carcinogen. The technique consists of the acid-induced removal of the pyrenyl moiety from the hemoglobin as the strongly fluorescent free tetrols and their isolation by bonded-phase extraction methods and subsequent quantitation by fluorescence/HPLC. With this procedure as little as 5 pg of tetrol can be detected. The assay was used to determine the amount of benzo[ a]pyrene-hemoglobin adduct formation in mice bearing a carcinogen-induced fibrosarcoma.

Cross-reactive cellular and humoral immunity to carcinogen-induced chicken fibrosarcomas. II. Effect of prior immunization with transplantable tumors on primary tumor incidence.

Primary carcinogen-induced (7,12-dimethyl-benz[a]anthracene; DMBA) tumor-bearing SC chickens (B2/B2) frequently showed antibodies in their sera which reacted with cells from their autochthonous tumors, chicken embryo fibroblasts (CEF), tumor cells from some transplantable tumor lines, and from approximately 10% of other primary tumors. Similar results were obtained by ELISA on glutaraldehyde-fixed cells and by immunofluorescence on viable cells. The serum antibody reactivity could be removed by absorption with CEF but not with non-cross-reacting primary tumor cells or a variety of normal tissues. Although sera from normal chickens never showed significant reactivity, a high percentage of sera from chickens that had been injected with DMBA but failed to develop detectable tumors showed antibody activity to a transplantable DMBA-induced tumor and to CEF. On the basis of previously established cross-reactivity patterns in protective immunity to transplantable carcinogen-induced fibrosarcomas, attempts were made to protect against chemical carcinogenesis by prior immunization with selected DMBA-induced transplantable tumors. Tumor-immune chickens showed a significant decrease in the development of tumors during the first 3 mo after injection of DMBA (p = 0.001) or methylcholanthrene (p = 0.033) when compared to controls. This resistance to tumor induction in immune chickens was correlated to the degree of tumor immunity to the immunizing tumor present 1 mo after carcinogen injection (p = 0.046). There was, however, no detectable difference in the incidence of tumors arising later than 3 mo after carcinogen injection. The reduction in tumor incidence in immune as compared to control chickens at 5 mo was therefore less striking than the reduction seen at 3 mo. Immunization with CEF and adjuvants or with adjuvants alone afforded no protection to tumor induction.

Immunity to transplantable carcinogen-induced fibrosarcomas in B2/B2 chickens: I. Use of bacterial adjuvants in induction of immunity demonstrable in Winn tests

Tumor line specific immunity could be induced in chickens with the use of BCG or CP. Direct contact between bacteria and tumor cells was required for immunity induction, but succeeded only in animals which also had been previously injected with the same bacterial vaccine. While other methods such as iv injected live mitomycin treated tumor was capable of inducing immunity, only BCG or CP mediated immunity was capable of being adoptively transferred in the Winn assay. Bursectomized agamma-globulinemic chickens also produced strong transferable immunity. Crossreactivity between transplant lines was detectable upon rechallenge of immune donors but was not evident upon adoptive immunity transfer. Immunity was detectable in the spleen and in peripheral blood lymphocytes but could not be transferred by thymus cells.

In vitro induction of tumour-specific immunity V. Detection of common antigenic determinatnts of murine fibrosarcomas.

Two 3-methylcholanthrene and a spontaneous BALB/c fibrosarcoma were examined for tumour-associated antigens (TAA) by in vivo and in vitro induction of tumour-immune responses. When BALB/c mice were immunized to these fibrosarcomas by surgical tumour removal, cross-reacting tumour-associated transplantation antigens (TATA) were detected on all 3 tumours. Cytotoxic effector cells (CL) were then induced in vitro by co-culture of BALB/c spleen cells with the spontaneous, or one of the carcinogen-induced fibrosarcomas. These CL were shown to be cytotoxic T cells (Tc) and to be directed against cross-reacting TAA on all 3 tumours, by two in vitro 51Cr-release assay systems, direct 51Cr-release cytotoxicity and cellular competitive inhibition of 51Cr release. Further studies demonstrated that the fibrosarcoma TAA involved in in vitro induction of Tc were not present on normal adult or foetal tissues. A secondary cytotoxic response was also detected in vitro when spleen cells from mice immunized to a carcinogen-induced fibrosarcoma were tested. The patterns of cross-reactivity detected by the in vivo and primary in vitro tumour-immune responses suggested that the TAA detected in vivo (TATA) were not identical to the TAA detected in vitro.