Site Of Tumor Inoculation Research Articles

Multifaceted Pt Nanoclusters for Targeting Recognition, Cellular Uptake, and Therapy In Vivo and In Vitro in Chronic Myeloid Leukemia Cells

In the past few years, platinum nanomaterials (Pt NMs) have gained attraction owing to their ability to address the drawbacks of classical Pt-based chemotherapy drugs including drug resistance and clinical side effects, which have been preliminarily used in lung cancer, liver cancer, gynecological cancer, etc. In order to investigate the effect of Pt NMs on hematopoietic tumors, ultra-small Pt nanoclusters (Pt NCs) were employed to clarify their targeting recognition, cellular uptake, and effective therapy in vivo for chronic myeloid leukemia (CML) cells. Through the facile surface modification of Pt NCs with anti-CD19 to form the anti-CD19-Pt NC composite, the specific aggregation in BV173 cells could be realized based on their high protein expression of CD19 in comparison to that in CD19-negative K562 cells. Furthermore, the endocytic pathways of Pt NCs in K562 and BV173 cells were investigated by qualitative and quantitative analyses via inductively coupled plasma-optical emission spectroscopy and flow cytometry. It was observed that Pt NCs entered into the K562 cells mainly through the caveolin-dependent endocytic pathway and in BV173 cells primarily via phagocytosis and micropinocytosis. Moreover, these Pt NCs exerted an excellent inhibitory effect on proliferation, migration, and invasion of hematopoietic tumor cells and tended to gather the acidic organelles (lysosomes or endosomes), resulting in the proliferation inhibition of tumor cells by the generation of corrosive Pt. Notably, Pt NCs were significantly aggregated at the site of tumor inoculation in mice and exhibited satisfactory in vivo inhibition of the increase in tumor weight and its size under the premise of not damaging the liver and spleen. Thus, the merits of versatile Pt NCs included facile target recognition, explicit cellular uptake behavior, and therapeutic efficacy in vivo, thereby hinting at their promising prospects for the clinical diagnosis and treatment of hematological malignancies.

Kinsenoside Protects Against Radiation-Induced Liver Fibrosis via Downregulating Connective Tissue Growth Factor Through TGF-β1 Signaling.

Radiation-induced liver fibrosis (RILF) is a serious complication of the radiotherapy of liver cancer, which lacks effective prevention and treatment measures. Kinsenoside (KD) is a monomeric glycoside isolated from Anoectochilus roxburghii, which has been reported to show protective effect on the early progression of liver fibrosis. However, the role of KD in affecting RILF remains unknown. Here, we found that KD alleviated RILF via downregulating connective tissue growth factor (CTGF) through TGF-β1 signaling. Sprague-Dawley rats were administered with 20 mg/kg KD per day for 8 weeks after a single 30Gy irradiation on the right part of liver, and tumor-bearing nude mice were administered with 30 mg/kg KD per day after a single fraction of 10Gy on the tumor inoculation site. Twenty-four weeks postirradiation, we found that the administration of KD after irradiation resulted in decreased expression of α-SMA and fibronectin in the liver tissue while had no adverse effect on the tumor radiotherapy. Besides, KD inhibited the activation of hepatic stellate cells (HSCs) postirradiation via targeting CTGF as indicated by the transcriptome sequencing. Results of the pathway enrichment and immunohistochemistry suggested that KD reduced the expression of TGF-β1 protein after radiotherapy, and exogenous TGF-β1 induced HSCs to produce α-SMA and other fibrosis-related proteins. The content of activated TGF-β1 in the supernatant decreased after treatment with KD. In addition, KD inhibited the expression of the fibrosis-related proteins by regulating the TGF-β1/Smad/CTGF pathway, resulting in the intervention of liver fibrosis. In conclusion, this study revealed that KD alleviated RILF through the regulation of TGFβ1/Smad/CTGF pathway with no side effects on the tumor therapy. KD, in combination with blocking the TGF-β1 pathway and CTGF molecule or not, may become the innovative and effective treatment for RILF.

Localized PD-1 Blockade in a Mouse Model of Renal Cell Carcinoma.

Herein we report the impact of localized delivery of an anti-mouse PD-1-specific monoclonal antibody (aPD1) on Renca tumors in the resulting T cell responses and changes in broader immune gene expression profiles. Renca is a BALB/c mice syngeneic tumor that has been used to model human renal cell carcinoma In this study, T cell subsets were examined in tumors and draining lymph nodes of mice treated with localized PD-1 with and without the addition of adenosine deaminase (ADA), an enzyme that catabolizes adenosine (ADO), identified as an immune checkpoint in several types of human cancers. The biologics, aPD1, or aPD1 with adenosine deaminase (aPD1/ADA), were formulated with the self-assembling peptides Z15_EAK to enhance retention near the tumor inoculation site. We found that both aPD1 and aPD1/ADA skewed the local immune milieu towards an immune stimulatory phenotype by reducing Tregs, increasing CD8 T cell infiltration, and upregulating IFNɣ. Analysis of tumor specimens using bulk RNA-Seq confirmed the impact of the localized aPD1 treatment and revealed differential gene expressions elicited by the loco-regional treatment. The effects of ADA and Z15_EAK were limited to tumor growth delay and lymph node enlargement. These results support the notion of expanding the use of locoregional PD-1 blockade in solid tumors.

Retraction of "Glioma Gene Therapy Using Induced Pluripotent Stem Cell Derived Neural Stem Cells".

Using neural stem cells (NSCs) with tumor tropic migratory capacity to deliver therapeutic genes is an attractive strategy in eliminating metastatic or disseminated tumors. While different methods have been developed to isolate or generate NSCs, it has not been assessed whether induced pluripotent stem (iPS) cells, a type of pluripotent stem cells that hold great potential for regenerative medicine, can be used as a source for derivation of NSCs with tumor tropism. In this study, we used a conventional lentivirus transduction method to derive iPS cells from primary mouse embryonic fibroblasts and then generated NSCs from the iPS cells. To investigate whether the iPS cell derived NSCs can be used in the treatment of disseminated brain tumors, the cells were transduced with a baculoviral vector containing the herpes simplex virus thymidine kinase suicide gene and injected into the cerebral hemisphere contralateral to a tumor inoculation site in a mouse intracranial human glioma xenograft model. We observed that NSCs expressing the suicide gene were, in the presence of ganciclovir, effective in inhibiting the growth of the glioma xenografts and prolonging survival of tumor-bearing mice. Our findings provide evidence for the feasibility of using iPS cell derived NSCs as cellular vehicles for targeted anticancer gene therapy.

Abstract 634: Impact of tumor inoculation site on the development of cancer cachexia

Abstract Background and Aim The incidence of cancer cachexia varies greatly among tumor type. Although certain tumor types are more commonly associated with cachexia, even for the same tumor type, the degree to which patients exhibit cachexia varies. This is due to variations in tumor phenotype and host genotype that contributes to the development of cancer cachexia. The influence of the site of tumor growth on the development of cancer cachexia remains unclear. In this study, we evaluated if differences in tumor microenvironment would affect the development of cancer cachexia in a murine model. Methods The same number of colon26 cells (5×10⁁6 cells/mouse) was inoculated subcutaneously or intraperitoneally in 8-week-old male BALB/c mice. Body weight, food intake, and tumor size were monitored. On day 14 after the tumor inoculation, mice were anesthetized and blood collected, and the weight of peritesticular adipose tissue, gastrocnemius muscle and heart were measured. 23 plasma cytokines were determined by using the Bio-Plex array system and plasma Myostatin and Activin A levels were measured by ELISA. Expression of MuRF-1 and Antrogin-1, which are required for muscle atrophy, in gastrocnemius muscle or heart was assessed by RT-PCR. Results The body weight, adipose tissue and gastrocnemius muscle decreased in tumor-bearing mice. Interestingly, a reduction in heart weight was observed in the intraperitoneal tumor group but not in the subcutaneous group. The weight loss of the body, adipose tissue and gastrocnemius was more severe in the intraperitoneal group than in the subcutaneous group. Atrogin 1 and MuRF1 mRNA expressions in the gastrocnemius muscle increased significantly in both groups of tumor-bearing mice, however, in the myocardium, expression of these mRNAs increased in the intraperitoneal group but not in subcutaneous group. As for plasma cytokine levels, several cytokine levels including IL-6, TNF-α, and activing A of tumor-bearing mice were significantly higher than those of control mice. Eotaxin and G-CSF levels in the intraperitoneal tumor group were higher than in the subcutaneous group. Conclusion Based on these data, we believe that differences in microenvironment where tumor cells develop can affect the progression and phenotype of cancer cachexia through alterations in various circulating factors derived from the tumor microenvironment. Citation Format: Takashi Ando, Takeshi Ishikawa, Tastuzo Matsuyama, Tomoyo Yasuda, Toshifumi Doi, Tetsuya Okayama, Naoyuki Sakamoto, Satoshi Kokura, Yuji Naito, Yoshito Itoh. Impact of tumor inoculation site on the development of cancer cachexia. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 634.

Tumor inoculation site affects the development of cancer cachexia and muscle wasting.

The phenotype and severity of cancer cachexia differ among tumor types and metastatic site in individual patients. In this study, we evaluated if differences in tumor microenvironment would affect the development of cancer cachexia in a murine model, and demonstrated that body weight, adipose tissue and gastrocnemius muscle decreased in tumor-bearing mice. Interestingly, a reduction in heart weight was observed in the intraperitoneal tumor group but not in the subcutaneous group. We evaluated 23 circulating cytokines and members of the TGF-β family, and found that levels of IL-6, TNF-α and activin A increased in both groups of tumor-bearing mice. Eotaxin and G-CSF levels in the intraperitoneal tumor group were higher than in the subcutaneous group. Atrogin 1 and MuRF1 mRNA expressions in the gastrocnemius muscle increased significantly in both groups of tumor-bearing mice, however, in the myocardium, expression of these mRNAs increased in the intraperitoneal group but not in subcutaneous group. Based on these results, we believe that differences in microenvironment where tumor cells develop can affect the progression and phenotype of cancer cachexia through alterations in various circulating factors derived from the tumor microenvironment.

C5a Complement Depletion Suppresses In Vivo B Lymphoma Progression and Enhances Development Of Cellular Anti-Tumor Immune Response

BackgroundProteins within the complement system have complex effects on cellular immune responses. In previous studies, we found that active complement components, especially C5a, can dampen the development of antigen-specific immune responses following vaccination with a model antigen, in part by promoting generation of APC-induced T regulatory (Treg) cells. These studies also demonstrated that B lymphoma cell lines exposed to complement can induce Treg generation in vitro. The current study was designed to address whether depletion of C5a could enhance development of a cellular anti-lymphoma immune response in vivo. MethodsImmunocompetent Balb/C mice were inoculated subcutaneously with syngeneic A20 B lymphoma cells mixed with either 10 μg of rat anti-mouse C5a monoclonal antibody (mAb) or 10 μg of isotype-matched Rat IgG2a control mAb. Tumor growth was followed. In select experiments, mice were sacrificed and analyzed for the percentage and activity of tumor-infiltrating T cells and A20-specific splenic T cell responses. Results1. Tumor progression. Lymphoma grew more slowly in mice treated with anti-C5a mAb compared to mice treated with control mAb (p<0.05) {Fig. 1). [Display omitted] 2. Intratumoral T cells. Tumors from mice treated with anti-C5a mAb had higher CD8+ T cell infiltration compared to mice treated with control mAb (p=0.002) (Fig. 2). Tumor-infiltrating CD8+ T cells showed a trend towards higher intracellular IFNg production in mice treated with anti-C5a mAb compared to control mAb (p=0.051). [Display omitted] 3. Splenic T cells. Splenic T cells from mice treated with anti-C5a mAb produced IFNg to a greater degree than did splenic T cells from control mice when splenocytes were cultured with irradiated A20 cells in vitro (p=0.041) (Fig. 3). There was a trend towards decreased numbers of splenic CD4+CD25highFoxp3+ Tregs in C5a-depleted mice compared to control mice. [Display omitted] ConclusionsDepletion of C5a at the site of tumor inoculation slows tumor growth and increases the number of tumor infiltrating CD8 T cells in a syngenic immunocompetent model of lymphoma. A trend towards enhanced production of IFNg in the tumor infiltrating T cells, increased numbers of tumor-specific splenic T cells, and reduced numbers of splenic Tregs, suggests intratumoral C5a depletion can enhance tumor-specific immune responses both within the tumor and systemically. Ongoing studies are exploring the molecular mechanisms involved in C5a-promoted tumor progression and the use of C5a depletion as a novel strategy to improve anti-tumor immunity. Disclosures:No relevant conflicts of interest to declare.

Separation and Characterization of Epithelial and Mesenchymal-like Murine Mammary Tumor Cells Reveals Epithelial Cell Differentiation Plasticity and Enhanced Tumorigenicity of Epithelial-enriched Tumor Cells

Tumors are composed of heterogeneous populations of cells including tumor-initiating cells (TICs) and metastatic precursors. While the origin of these cells is unknown, there is evidence that tumor cells can transdifferentiate from an epithelial to a mesenchymal phenotype, a property referred to as epithelial-to-mesenchymal transition (EMT). This cellular plasticity may explain the heterogeneous nature of tumors and differences in the tumorigenic and invasive properties of cells. Understanding the origin of these cells and the contribution of external factors that influence the acquisition of cellular properties is critical for the development of therapeutics to eradicate cancer. In this study, we show that primary murine tumor cells harvested from FVB/N Tg (MMTV/Neu) spontaneous mammary tumors possess differentiation plasticity and can be enriched to be epithelial or mesenchymal-like using selected culture media conditions, and we show evidence of EMT in a clonal population of primary epithelial tumor cells when cultured in fibroblast growth factor-1 (FGF-1) or transforming growth factor-β (TGF-β). We also determined that in contrast to the identification of mesenchymal-like tumor cells as TICs in orthotopic xenograph models of tumorigenicity, epithelial-enriched murine mammary tumor cells were more tumorigenic as compared to mesenchymal-enriched cells when transplanted back subcutaneously into syngeneic immune competent mice. Together, these data suggest that EMT plasticity can be induced in primary murine mammary tumor cells, and that tumorigenicity of epithelial or mesenchymal-like cells may be influenced by factors such as the site of tumor inoculation or the immune state of the host (xenogenic immune compromised versus syngeneic immune competent).

Glioma Gene Therapy Using Induced Pluripotent Stem Cell Derived Neural Stem Cells

Using neural stem cells (NSCs) with tumor tropic migratory capacity to deliver therapeutic genes is an attractive strategy in eliminating metastatic or disseminated tumors. While different methods have been developed to isolate or generate NSCs, it has not been assessed whether induced pluripotent stem (iPS) cells, a type of pluripotent stem cells that hold great potential for regenerative medicine, can be used as a source for derivation of NSCs with tumor tropism. In this study, we used a conventional lentivirus transduction method to derive iPS cells from primary mouse embryonic fibroblasts and then generated NSCs from the iPS cells. To investigate whether the iPS cell derived NSCs can be used in the treatment of disseminated brain tumors, the cells were transduced with a baculoviral vector containing the herpes simplex virus thymidine kinase suicide gene and injected into the cerebral hemisphere contralateral to a tumor inoculation site in a mouse intracranial human glioma xenograft model. We observed that NSCs expressing the suicide gene were, in the presence of ganciclovir, effective in inhibiting the growth of the glioma xenografts and prolonging survival of tumor-bearing mice. Our findings provide evidence for the feasibility of using iPS cell derived NSCs as cellular vehicles for targeted anticancer gene therapy.

Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells as Cellular Delivery Vehicles for Prodrug Gene Therapy of Glioblastoma

Mesenchymal stem cells (MSCs) possess tumor-tropic properties and consequently have been used to deliver therapeutic agents for cancer treatment. Their potential in cancer therapy highlights the need for a consistent and renewable source for the production of uniform human MSCs suitable for clinical applications. In this study, we seek to investigate whether human embryonic stem cells can be used as a cell source to fulfill this goal. We generated MSC-like cells from two human embryonic stem cell lines, HuES9 and H1, and observed that MSC-like cells derived from human embryonic stem cells were able to migrate into human glioma intracranial xenografts after being injected into the cerebral hemisphere contralateral to the tumor inoculation site. We engineered these cells with baculoviral and lentiviral vectors, respectively, for transient and stable expression of the herpes simplex virus thymidine kinase gene. In tumor-bearing mice the engineered MSC-like cells were capable of inhibiting tumor growth and prolonging survival in the presence of ganciclovir after they were injected either directly into the xenografts or into the opposite hemisphere. Our findings suggest that human embryonic stem cell-derived MSCs may be a viable and attractive alternative for large-scale derivation of targeting vehicles for cancer therapy.

Biodistribution of antisense nanoparticles in mammary carcinoma rat model

Efficient and specific delivery of antisenses (ASs) and protection of the sequences from degradation are critical factors for effective therapy. Sustained release nanoparticles (NP) offer increased resistance to nuclease degradation, increased amounts of AS uptake, and the possibility of control in dosing and sustained duration of AS administration. The biodegradable and biocompatible poly(D,L-lactic-co-glycolic acid) copolymer (PLGA) was utilized to encapsulate AS directed against osteopontin (OPN), which is a promising therapeutic target in mammary carcinoma. Whole body biodistribution of OPN AS NP was evaluated in comparison to naked AS, in intact and mammary carcinoma metastasis model bearing rats. Naked and NP encapsulated AS exhibited different biodistribution profiles. AS NP, in contrast to naked AS, tended to accumulate mostly in the spleen, liver, and at the tumor inoculation site. Drug levels in intact organs were negligible. The elimination of naked AS was faster, due to rapid degradation of the unprotected sequence. It is concluded that AS NP protect the AS from degradation, provide efficient AS delivery to the tumor tissue, and minimize AS accumulation in intact organs due to the AS sustained release profile as well as the favorable NP physicochemical properties.

Massive T-Lymphocyte Infiltration into the Host Stroma Is Essential for Fibroblast Growth Factor-2-Promoted Growth and Metastasis of Mammary Tumors via Neovascular Stability

Inflammation in the tumor stroma greatly influences tumor development. In the present study, we investigated the roles of fibroblast growth factor (FGF)-2-induced chronic inflammation in the development of 4T1 murine mammary tumors. Administration of FGF-2 into the tumor inoculation site during the initial phase of tumor growth enhanced tumor growth and pulmonary metastasis as well as microvessel density in tumor tissues in normal but not in nude mice. Infiltration of T lymphocytes and macrophages, recruitment of pericytes/vascular mural cells in neovascular walls, and the expression levels of cyclooxygenase (COX)-2 and vascular endothelial growth factor A (VEGFA) were also enhanced in the FGF-2-activated host stroma of normal mice. In addition, FGF-2-induced tumor growth and metastasis was abrogated by administration of either an immunosuppressant, FK506, or a COX-2 inhibitor. FGF-2 enhanced prostaglandin E(2) secretion in cultured T lymphocytes. In addition, VEGFA secretion was increased in a co-culture of T lymphocytes and fibroblasts in vitro. These results indicate that the massive infiltration of T lymphocytes into FGF-2-activated host stroma during the initial phase of tumor growth enhances neovascular stability by regulating endogenous COX-2 and VEGFA levels because both compounds are known to play important roles in marked 4T1 mammary tumor development via FGF-2-induced inflammatory reactions.

Fibroblast growth factor‐2‐induced host stroma reaction during initial tumor growth promotes progression of mouse melanoma via vascular endothelial growth factor A‐dependent neovascularization

Fibroblast growth factor (FGF)-2 has been considered to play a critical role in neovascularization in several tumors; however, its precise role in tumor progression is not fully understood. In the present study, we have characterized the role of FGF-2 in B16-BL6 mouse melanoma cells, focusing on effects during the initial phase of tumor growth. FGF-2 was injected at the tumor inoculation site of dorsal skin during the initial phase. FGF-2 induced marked tumor growth and lymph node metastasis. This was well correlated with an increase in neovascularization in the host stroma. FGF-2 also recruited inflammatory and mesenchymal cells in host stroma. Marked tumor growth, pulmonary metastasis and intensive neovascularization in tumor parenchyma were also observed after a single injection of FGF-2 into the footpad inoculation site. In contrast, repeated injections of FGF-2 at a site remote from the footpad tumor were ineffective in promoting tumor growth and metastasis. These promoting activities of FGF-2 were blocked by local injections of a glucocorticoid hormone, suggesting that host inflammatory responses induced by FGF-2 are associated with FGF-2-induced tumor progression. In addition, although FGF-2 did not promote cellular proliferation and vascular endothelial growth factor A (VEGFA) mRNA expression in B16-BL6 cells in vitro, FGF-2 induced VEGFA expression in host stroma rather than tumor tissue, and local injections of a neutralizing antibody against VEGFA inhibited these activities of FGF-2 in vivo. These results indicate that abundant FGF-2 during the initial phase of tumor growth induces VEGFA-dependent intensive neovascularization in host stroma, and supports marked tumor growth and metastasis.

Induction of potent anti-tumor immunity by direct injection of Ad-LIGHT at the site of tumor inoculation

The aim of this study was to observe the therapeutic effects of adenovirus-mediated LIGHT gene transfer in murine B16 melanoma in vivo. C57BL/6 mice were inoculated subcutaneously with B16 cells to establish the murine melanoma model. The tumor-bearing mice were injected at the site of tumor inoculation with recombinant adenoviral vectors expressing the murine LIGHT gene. The tumor growth and survival period of tumor-bearing mice were observed. The splenic NK and CTL activity were measured in vitro by lactate dehydrogenase (LDH) release assay. The amounts of cytokines were determined with ELISA kits. The LIGHT gene could be efficiently transduced into tumor tissue after injection of Ad-LIGHT. Treatment with Ad-LIGHT significantly inhibited the tumor growth and prolonged the survival period of the tumor-bearing mice. The splenic NK and CTL activity of the mice was also enhanced after LIGHT gene transfer. The production of IL-2 and IFN-gamma from lymphocytes derived from mice treated with Ad-LIGHT was increased significantly compared with control groups. Our results indicate that local expression of the LIGHT gene can induce potent anti-tumor immunity and may be a promising treatment strategy for melanoma.

Interleukin-2 inhibits proliferation of HPV-associated tumor cells and halts tumor growth in vivo

Previous studies have shown inhibition of cervical cancer cell growth by treatment with high concentrations of IL-2. In the present study, we evaluated the in vitro and in vivo effects of recombinant human IL-2 on HPV-associated tumor cells (3T3-16). Treatment of 3T3-16 cells with rhIL-2 for 72 h inhibited cell growth in a dose-dependent manner and this effect was evidenced at nanomolar concentrations. These tumor cells expressed mRNA for β and γ subunits of the IL-2 receptor, which are required for signal transduction. In experiments to explore the effect of IL-2 on the growth of the HPV-associated tumor, mice received rhIL-2 through different routes: (i) intraperitoneal; (ii) subcutaneous, at the tumor inoculation site; or (iii) subcutaneous, distant from the tumor inoculation site. An effective antitumor response was observed only in those animals that received IL-2 at the tumor site ( P<0.01). These results indicate the potential adequacy of therapeutic strategies based on local administration of rhIL-2 for cervical carcinoma, not only based on the ability of this cytokine to stimulate cellular-mediated immunity but also because of its direct effects on tumor cells.

Cyclophosphamide induces the development of early myeloid cells suppressing tumor cell growth by a nitric oxide-dependent mechanism.

Adoptive immunotherapy with cyclophosphamide (Cy) increases the host resistance against tumor growth. The precise mechanism(s) by which this therapy enhances tumor suppression is unclear. Cy induces the development of early myeloid cells that may be strongly antiproliferative through NO production. These cells are similar to the natural suppressor cells found in normal bone marrow with a potential antitumor effect. Here we have addressed whether the development of NO-producing cells may be involved in this tumor resistance in Cy-treated mice. The results show a synergism between Cy treatment and tumor-specific lymphocytes transferred systemically (i.v.) or locally (Winn's assay) that results in a strong tumor suppression. Inhibition of NO production by N(G)-monomethyl-L-arginine at the site of tumor inoculation results in a loss of the protection achieved by the combined therapy. Cy-treated mice develop splenic early myeloid (CD11b, Gr-1, CD31 (ER-MP12), ER-MP20, ER-MP54) cells producing large amounts of NO upon T cell-derived signals (IFN-gamma plus CD40 ligation) able to inhibit tumor cell growth in vitro. Early myeloid cells (ER-MP54(+)) and cells expressing inducible NO synthase are increased at the site of tumor challenge in mice treated with the combined therapy, but not in those treated with Cy or immune cell transfer alone. Thus, Cy induces the expansion of early myeloid cells, inhibiting tumor cell growth by a mechanism involving NO. Both the recruitment and the activation of these myeloid cells at the site of tumor challenge appear to be dependent on the presence of tumor-specific lymphocytes.

Engraftment of human tumor-infiltrating lymphocytes and the production of anti-tumor antibodies in SCID mice.

We report here the placement of nondisrupted 1-mm3 pieces of fresh human lung tumor biopsy tissue into the subcutis of severe combined immunodeficient (SCID) mice results in the engraftment of tumor-infiltrating leukocytes (TIL) in all but 5 of 148 mice inoculated with 39 different biopsy tissue specimens. In mice coengrafted with tumor and TIL the normal histologic architecture of the tumor and TIL interface was maintained for up to 22 wk. The TIL in the xenograft were shown to divide and were maintained exclusively at the site of tumor inoculation. It is established here that plasma cells in the TIL population produce Abs that react in western blots with tumor cell lysates. These Abs were shown to react with high and low m.w. proteins derived from both the membrane and cytosolic fractions of tumor cell lysates. The production of human Ig was found to be T cell dependent, and immunohistochemistry and in situ hybridization of DNA, using a human-specific cDNA probe, established the human identity of the tumor and TIL. High levels of human Ig in the sera of mice inoculated with tumor biopsy tissue are associated with the growth arrest of adenocarcinoma xenografts. Our results establish the co-engraftment of human tumors and TIL into SCID mice as new animal model with which to evaluate TIL function and novel therapeutic strategies that are designed to augment TIL anti-tumor activity.

Secretion of both IL-2 and IL-4 by tumor cells results in rejection and immunity.

The generation of a therapeutic immune response to malignancy is critically dependent on the inherent immunogenicity of the tumor. Our study demonstrates that secretion of both interleukin-2 (IL-2) and IL-4 by a seemingly nonimmunogenic tumor abrogates tumorigenicity, and mice that have rejected the genetically modified tumor are immune to challenges with the parental tumor. The induction of immunity by the IL-2/IL-4-secreting tumor was significantly better than that achieved with the admixture of tumor cells and the classic adjuvant, Corynebacterium parvum. To elicit a primary immune response, the majority of cells needed to secrete both cytokines. Ad-mixture of IL-2-secreting cells with IL-4-secreting cells did not result in tumor cell rejection. The IL-2/IL-4-secreting tumor cells were efficiently rejected in animals immunosuppressed by total body irradiation. Depletion of CD4+ or CD8+ T cells did not abrogate rejection of the tumor cells, but the animals depleted of CD4 cells failed to generate protective immunity. Our study demonstrates that secretion of the combination of IL-2 and IL-4 significantly enhances tumor immunogenicity. The requirement of cells secreting both cytokines suggests an intricate mechanism different from the mere presence of both cytokines at the tumor-inoculation site.

Treatment of Murine Transitional Cell Carcinoma with Intralesional Interleukin 2 and Murine Interferon Gamma

The antitumor effect of intralesionally administered recombinant interleukin-2, alone or in combination with recombinant interferon gamma was studied in murine transitional cell carcinoma, MBT2. In the initial prophylactic model treatment was started at day one at the site of tumor inoculation. Maximal and significant reduction in tumor volume occurred in groups receiving 4,000 units of recombinant interleukin 2 and 107 colony forming units Bacillus Calmette Guerin (p <0.00001 vs saline control). In the same experiment, a reduction in tumor incidence and increase in survival occurred in groups receiving 4,000 units of recombinant interleukin 2, 1,000 units of recombinant interleukin 2 plus 2,000 units of recombinant interferon gamma, as well as 107 colony forming units Bacillus Calmette Guerin relative to saline control (p <0.005).The dose-response effect of recombinant interleukin 2 alone was also tested in a model of an established transitional cell carcinoma. Intralesional injection treatments were initiated after tumors were palpable. Reduction in tumor volume was observed in the group receiving 8,000 units of recombinant interleukin 2 (p = 0.01 vs saline control), but no significant advantage in survival was noted.

TERMINATION OF IMMUNE PRIVILEGE IN THE ANTERIOR CHAMBER OF THE EYE WHEN TUMOR-INFILTRATING LYMPHOCYTES ACQUIRE CYTOLYTIC FUNCTION

Minor H incompatible P815 tumor cells form progressively growing intraocular tumors when injected into the anterior chamber of eyes of BALB/c mice (an immunologically privileged site), but these tumor cells are promptly rejected when injected into the subconjunctival space. In both circumstances, the tumor inoculation site acquires significant numbers of DBA/2-specific precursor cytotoxic T cells (pTc) but only at the subconjunctival site do fully functional cytotoxic T cells (Tc) emerge, and their emergence coincides temporally with rejection of the tumor graft. In the present study, we wished to determine whether pTc can differentiate into Tc within the anterior chamber of the eye and whether the failure of BALB/c mice to reject intraocular P815 tumors is related to this putative block in pTc differentiation. It was previously shown that P815 tumor cells injected into the eyes of MHC-incompatible C57BL/6 mice are able to grow transiently within the anterior chamber and that they are eventually rejected. We have examined the local cytotoxic T cell responses during and after the transient phase of immune privilege that is extended to MHC-incompatible tumor grafts in eyes of C57BL/6 mice. Our results indicate that termination of immune privilege (rejection of the tumor implant) coincides with the detection of fully functional Tc within the tumor-containing eye. Circumstantial evidence suggests that these tumors are infiltrated with DBA/2-specific pTc during the phase of progressive tumor growth and that it is these infiltrating cells that differentiate in oculi into the Tc that effect graft rejection. These findings support the hypotheses that immune privilege in the anterior chamber of the eye is an actively maintained process that suppresses terminal differentiation of pTc and that privilege is abolished if conversion of pTc to Tc is accomplished.