The biological characteristics of adenovirus-mediated il-18 gene-modified murine colorectal adenocarcinoma cellin vivo andin vitro

Objective: Interleukin 18 (IL-18) is a strong activator of NK cells and promotes the generation of IL-2, IFN-γ and GM-CSF. In the present study, we constructed adenovirus encoding IL-18 gene (AdIL-18), and observed the biological characteristics of IL-18 gene-modified murine colorectal adenocarcinoma cell (CT26)in vivo andin vitro. Methods: Gene modification was mediated by adenovirus. The proliferation of the cells was determined by MTT and IL-18 was assayed by ELISA. The cytotoxicity of NK and CTL was detected by four-hour⁵¹Cr release assay. Results: IL-18 gene modification had no effect on the proliferation and morphology of CT-26 cellsin vitro, but the growth of IL-18-modified CT26 cells was obviously inhibitedin vivo. In addition, although IL-18-modified CT26 cells could form tumor nodulesin vivo as well as LacZ-modified CT26 cells or wild-type CT26 cells, the mean survival time of the mice inoculated with IL-18-modified CT26 cells was significantly prolonged as compared with that of control groups. Thus, the anti-tumor immune responses were induced in the group of mice inoculated with IL-18-modified CT26 cells, which might be related to the activation of NK cells and CTL. However, all the three groups ultimately died of tumor. Conclusion: IL-18-modified CT26 cells could induce the anti-tumor immune responses incompletely, which required other factors for effective anti-tumor responses. Foundation item: This work was supported by National Natural Science Foundation of China (No. 39970689) and Natural Science Foundation of Shanghai (No. 99QB14047). Biography: SONG Wen-gang (1964-), associate professor, majors in cancer immunology, present address: Taishan Medical College.     

腺病毒介导IL-2基因转染的瘤苗体内抗肿瘤作用

目的 :探讨重组腺病毒介导的 IL- 2基因转染的瘤苗的体内抗肿瘤作用及其免疫学机制。方法 :应用腺病毒介导的鼠 IL- 2基因转染 CT2 6小鼠结肠癌细胞 ,灭活后用作瘤苗治疗荷瘤小鼠 ,观察皮下肿瘤生长及其存活期。采用乳酸脱氢酶释放法检测荷瘤小鼠脾细胞 CTL、L AK、NK细胞的杀伤活性。结果 :鼠 IL- 2基因转染瘤苗治疗能显著抑制荷瘤小鼠皮下肿瘤生长并明显延长其存活期 (P<0 .0 1)。体内免疫功能检测表明 ,鼠 IL- 2基因转染疫苗治疗组小鼠脾细胞 CTL 活性、L AK活性和 NK活性显著高于对照组 (P<0 .0 1)。结论 :腺病毒介导鼠 IL- 2基因转染的瘤苗体内具有较强的抗肿瘤效应 ,其机制可能是提高了荷瘤小鼠特异性和非特异性抗肿瘤免疫反应     

Effects of hMIP-1beta gene modification on in vivo tumorigenicity and vaccine efficacy of tumor cells

OBJECTIVE To explore the effects of human macrophage inflammatory protein-1 beta (hMIP-1beta) modification on the in vivo tumorigenicity and vaccine efficacy of tumor cells. METHODS: Murine colorectal adenocarcinoma CT26 cells were transfected with a recombinant adenovirus carring the hMIP-1beta gene (AdhMIP-1beta). The efficacy of gene transfection was tested by X-gal staining. The hMIP-1beta level in the supernatant of hMIP-1beta gene-modified CT26 cells was assayed by ELISA, and the chemotactic activity for CD4+ T cells, CD8+ T cells, NK cells and immature dendritic cells (imDCs) were assayed by a transwell chamber. The changes of growth characteristics and in vivo tumorigenicity of hMIP-1beta gene-modified CT26 cells were also assessed. BALB/c mice were immunized with hMIP-1beta gene-modified CT26 tumor vaccine and the antitumor effect was evaluated. RESULTS: hMIP-1beta gene could be transfected into CT26 cells by AdhMIP-1beta with an efficiency over 95%. The level of hMIP-1beta in the culture supernatant of hMIP-1beta gene-modified CT26 cells was 980 pg/ml and the supernatant displayed ramarkable chemotactic activity to CD4+ T cells, CD8+ T cells, NK cells and imDCs compared with LacZ gene-modified CT26 cells and control. When the hMIP-1beta gene-modifited CT26 cells were subcutaneously inoculated in BALB/c mice, the tumorigencity was delayed and suppressed, and overt necrosis and lymphocyte infiltration were observed in the tumor tissue, but not in those inoculated with LacZ gene-modified CT26 cells or parental CT26 cells. The mice immunized with hMIP-1beta gene-modified CT26 tumor vaccine could induce tumor specific CTL activity and nonspecific NK activity, and exhibited resistance to later challenge with wild-type CT26 cells. CONCLUSION: hMIP-1beta gene-modified CT26 cells exhibit decreased tumorigenicity, and hMIP-1beta gene-modified tumor vaccine may induce a powerful specific and nonspecific antitumor response. The data suggested that hMIP-1beta gene-modified tumor vaccine may play a potent role in prevention of metastasis and recurrence of malignant tumors.     

IL-18基因修饰增强肿瘤细胞裂解物致敏的树突状细胞的抗肿瘤效应

目的:观察经肿瘤细胞裂解物致敏的白细胞介素18(IL-18)基因修饰的树突状细胞(DC)体内诱导的抗肿瘤免疫应答反应.方法:体外培养的小鼠骨髓树突状细胞经IL-18重组腺病毒感染后(IL18-DC),再经Hepal-6肝癌细胞裂解物冲击致敏后通过皮下注射用于荷瘤小鼠的治疗.用ELISA检测细胞因子,4 h51Cr释放法检测NK细胞活性及CTL杀伤活性.结果:致敏IL18-DC组体内诱导NK细胞活性与未致敏IL18-DC组无明显差别(P＞0.05),但明显高于致敏DC组和DC组(均P＜0.01);致敏IL18-DC组体内诱导特异性CTL杀伤活性明显高于IL18-DC组、致敏DC组和DC组(均P＜0.01);致敏IL18-DC组免疫治疗作用明显优于未致敏IL18-DC组、致敏DC组和DC组(均P＜0.01).结论:肿瘤细胞裂解物致敏的IL-18基因修饰的DC疫苗进行体内免疫治疗,能诱导出显著的抗肿瘤免疫反应,为DC介导的肿瘤基因治疗开辟了新的途径.     

Spleen-derived dendritic cells engineered to enhance interleukin-12 production elicit therapeutic antitumor immune responses

The major goal in cancer immunotherapy is the induction of tumor-specific T lymphocytes capable of killing tumor cells. As both dendritic cells (DCs) and interleukin-12 (IL-12) can play immunostimulatory roles in vivo, the use of a combination of these has become a promising approach. In the present study, we used a murine tumor model to examine whether spleen-derived DCs transduced with the IL-12 gene could elicit tumor-specific immune responses. BALB/c mice injected peritumorally with adenovirus-mediated IL-12 gene-transduced antigen-unpulsed DCs inhibited the growth of day 5-established subcutaneous CT26 tumors. Splenocytes from treated mice responded specifically to parental tumor cells and showed increased production of interferon gamma (IFN-gamma) and antitumor cytotoxic T-lymphocyte (CTL) activity. Increased numbers of both CD4(+) and CD8(+) T cells were detected in the treated tumors. The inhibition of tumor growth was significantly greater in mice injected with IL-12 gene-transduced DCs than in those injected with IL-12 gene-transduced fibroblasts or the IL-12 gene-encoding adenovirus itself. Taken together, these results indicate that DCs transduced with the IL-12 gene by a recombinant adenovirus are effective in inducing tumor-specific Th1 and CTL responses that inhibit the growth of established subcutaneous tumors.     

NK and CD8+ T cell-mediated eradication of poorly immunogenic B16-F10 melanoma by the combined action of IL-12 gene therapy and 4-1BB costimulation

In previous reports, systemic administration of a stimulatory monoclonal antibody directed against the 4-1BB receptor had no effect on survival or tumor burden in mice inoculated with the poorly immunogenic B16-F10 melanoma. We combined IL-12 gene transfer with 4-1BB costimulation to explore a previously noted cooperative anti-tumor effect against this model tumor. We hypothesize that the innate immune response mediated by IL-12-activated natural killer (NK) cells initiates the activation of the immune system, leading to the priming of T cells, whereas 4-1BB costimulation enhances the function of primed tumor-specific T cells. The effect of the combination therapy on the growth of subcutaneous (s.c.) tumors and pulmonary metastasis was examined. The combination therapy significantly retarded the growth of subcutaneously-inoculated tumors, and 50% of tumor-bearing mice survived with complete tumor regression. In contrast, neither IL-12 gene transfer nor anti-4-1BB antibody administration alone was as effective. Enhanced CTL activity against both B16-F10 tumor cells and TRP-2-pulsed EL4 syngeneic tumor cells was observed in tumor-bearing animals treated with the combination therapy 2 weeks after treatment and, in long-term survivors from this combination therapy, at >120 days. In a pulmonary metastatic model, only the combination therapy generated significant protection against metastasis. In vivo depletion of NK or CD8(+) but not CD4(+) subsets eliminated the protective immunity. Furthermore, NK cell depletion significantly reduced both tumor-specific CTL activity and the number of tumor-specific IFN-gamma-producing cells, suggesting that this synergistic effect requires the participation of both NK and CD8(+) T cells.     

糖化重组生存素腺病毒疫苗抗肿瘤作用的实验研究

背景与目的：生存素在调控细胞凋亡和有丝分裂过程中起着重要作用,在正常分化的组织中不表达或表达极低,而在胚胎组织和大部分肿瘤组织中广泛表达,而这一特点为恶性肿瘤的基因治疗提供了很好的靶标.本研究制备糖化重组生存素腺病毒疫苗,观察其抗肿瘤作用并探讨其作用机制.方法：将重组生存素腺病毒和甘露聚糖在氧化条件下偶联,同时建立小鼠结肠癌和Lewis肺癌模型,以糖化重组生存素腺病毒疫苗治疗荷瘤小鼠,观察肿瘤体积和小鼠生存时间.对小鼠肿瘤组织作TUNEL染色观察肿瘤细胞凋亡.为了检测疫苗的保护作用,预先以糖化重组生存素腺病毒疫苗免疫接种小鼠,或合用抗CD4、CD8和NK单克隆抗体阻断相应的淋巴细胞亚群,再接种肿瘤,观察小鼠肿瘤生长情况.结果：糖化重组生存素腺病毒疫苗治疗组小鼠肿瘤生长受到明显抑制,无明显不良反应发生,小鼠的生存时间明显延长,肿瘤细胞凋亡明显增加.同时,糖化重组生存素腺病毒疫苗能诱导小鼠产生抗肿瘤免疫,这一免疫反应依赖于CD4和CD8淋巴细胞,也部分依赖于NK细胞.结论：糖化重组生存素腺病毒疫苗能诱导机体产生特异性的主动免疫反应,诱导肿瘤细胞凋亡,具有明确的抗肿瘤作用,值得进一步研究.     

Inhibition of tumor metastasis by adoptive transfer of IL-12-activated Valpha14 NKT cells

A unique lymphocyte lineage, the Valpha14 NKT cells, expresses both NK1.1 and an invariant antigen receptor encoded by Valpha14 and Jalpha281 gene segments. Valpha14 NKT cells play crucial roles in various immune responses, including autoimmune diseases, allergic reactions and anti-tumor immunity. Valpha14 NKT cells were demonstrated to be essential for anti-tumor effect of IL-12 in vivo. Here, we report that adoptive transfer of IL-12-activated Valpha14 NKT cells prevents hepatic metastasis of B16 melanoma. The injection of large amounts of IL-2, IL-4, and IFN-gamma, which are cytokines produced by activated Valpha14 NKT cells, exhibited no significant inhibition of the metastasis of this melanoma. The cells prepared from the liver of IL-12-injected mice expressed a potent cytotoxic activity on B16 melanoma cells in vitro. Although the adoptive transfer of IL-12-activated Valpha14 NKT cells prevents hepatic metastasis of B16 melanoma, activated NK cells from IL-12-injected RAG-1-/- mice failed to inhibit the metastasis of this melanoma. Thus, the anti-tumor effect of IL-12 can be replaced by adoptive transfer of IL-12-activated Valpha14 NKT cells but not by IL-12-activated NK cells, suggesting a minor role of NK cells for the IL-12-mediated anti-tumor effect in this experimental system. Moreover, our studies have suggested the involvement of direct cytotoxic mechanisms rather than cytokine-mediated immune responses at the effector phase of the Valpha14 NKT cell-mediated anti-tumor activity.     

雷公藤内酯醇对人宫颈癌细胞的凋亡诱导效应

目的:探讨腺病毒介导AFP基因修饰的DC(AFP-DC)瘤苗经不同途径免疫后机体抗肿瘤免疫应答反应.方法:采用皮下注射、静脉注射和瘤体注射三种途径回输AFP-DC瘤苗,比较观察AFP-DC瘤苗对荷瘤小鼠免疫治疗作用,应用4h51cr释放杀伤实验、T细胞与NK体内剔除实验等方法,观察AFP-DC瘤苗对荷瘤小鼠免疫治疗作用及保护性免疫反应.结果:皮下注射AFP-DC瘤苗治疗效果在抑制肿瘤生长、延长小鼠存活期方面都明显优于瘤体内注射或尾静脉注射(P＜0.05),AFP-DC瘤苗体内能更有效地诱导特异CTL细胞毒活性,能使免疫动物产生一定的免疫保护作用,抵抗肿瘤细胞的再攻击.在AFP-DC瘤苗诱导抗肿瘤免疫排斥反应过程中,必需有CD4 T和CD8 T细胞的参与;而在其效应阶段,则依赖于CD8 T细胞的参与,CD4 T细胞为非必需;在免疫诱导及效应阶段剔除NK细胞对抗肿瘤免疫应答无明显影响.结论:皮下注射AFP-DC瘤苗能有效诱导机体产生抗肿瘤免疫反应,为DC介导的肝癌免疫治疗开辟了新的途径.     

IL-23基因修饰的树突细胞疫苗联合β-榄香烯对小鼠胰腺癌生长的影响

背景与目的:树突细胞(dendriticcells,DC)疫苗是目前最具应用潜能的治疗性疫苗,功能性细胞因子能显著增强DC的活性及其诱导的宿主抗肿瘤作用,利用细胞因子基因修饰DC是当今肿瘤免疫治疗中最活跃的领域。本研究探讨β-榄香烯联合白细胞介素-23(interleukin-23,IL-23)修饰的DC疫苗对胰腺癌小鼠的协同抗肿瘤作用。方法:克隆并构建IL-23基因真核双表达载体,转染DC并负载肿瘤抗原后制备成疫苗。将IL-23基因转染的DC疫苗、空质粒转染的DC疫苗、未转染的DC疫苗及对照生理盐水分别注射小鼠,体外观察各组小鼠脾脏T淋巴细胞IFN-γ及IL-4的分泌。体内观察β-榄香烯联合DC疫苗对荷胰腺癌小鼠肿瘤生长的抑制作用及对小鼠存活期的影响。结果:基因测序证实IL-23基因克隆及双表达载体构建成功,转染后DC共刺激分子MHC-Ⅰ和MHC-Ⅱ的表达增强。接种IL-23转染DC疫苗后小鼠的免疫防御能力显著增强,有效地延缓并防御接种肿瘤的发生。DC介导的免疫应答促进了IFN-γ生成型Th1细胞的产生,未转染DC疫苗组和空质粒转染DC疫苗组IL-4分泌量与IL-23转染的DC疫苗组比较差异有显著性(P<0.05);IL-23转染DC疫苗组IFN-γ的分泌与其他各组比较差异有显著性(P<0.01)。β-榄香烯联合IL-23转染DC疫苗组肿瘤生长受到显著抑制,该组小鼠存活期与DC组、NS对照组及β-榄香烯组比较差异有极显著性(P<0.01)。结论:IL-23修饰DC疫苗可强化宿主针对特异肿瘤的Th1及CTL的免疫应答,使宿主不仅产生防御性免疫反应而且增强自动免疫能力。β-榄香烯有一定的协同抗癌作用。     

Effect of GM-CSF and IL-2 co-expression on the anti-tumor immune response

We evaluated the effect of potential therapeutic genes, GM-CSF and IL-2 respectively, or in combination of both cytokines, on the activation of systemic antitumor responses. CT26 tumor cells were modified to secrete GM-CSF and/or IL-2. The growth rate of the modified tumor cells versus the parental CT26 cells did not show any difference. When we implanted the CT26 tumor cells which secrete either GM-CSF or IL-2, delayed and suppressed tumorigenicity was observed. However, another CT26 cell line which expresses both GM-CSF and IL-2 (CT26/GMCSF/IL-2) did not form any tumor mass in the immunocompetent syngeneic Balb/c mice, showing the potential immune responses. Immunohistochemical examination of the modified tumor masses implanted with the cells expressing GM-CSF or IL-2 showed increased necrosis and infiltration of NK (CD56+) lineage cells and macrophage/monocytes. In the vaccination model, the growth of rechallenged wild-type CT26 was more suppressed int he mice which were injected with GM-CSF or IL-2, however, the wild-type CT26 tumor formed normal tumor mass in the mice vaccinated with CT26/GM-CSF/IL-2 showing acute non-T-cell mediated immune response. As a treatment, we injected those modified tumor cells into the established tumor. There we could find tumor growth suppression by the injection of cytokine-modified CT26 cells, especially by the CT26/GM-CSF/IL-2. In the present study we could induce the eradication of tumorigenicity by the transfection of both GM-CSF and IL-2 genes and a potent role in the growth suppression of an established tumor.     

Regression of engineered myeloma cells secreting interferon-gamma-inducing factor is mediated by both CD4(+)/CD8(+) T and natural killer cells

IL-18 is a novel cytokine that stimulates T and NK cell activity and has potent antitumor effects. In this study, a mouse IL-18 gene was transfected into the mouse myeloma cell line J558. Our data demonstrated that (i) inoculation of 0.5x10(6) engineered tumor cells J558/IL-18 into syngeneic mice induced a Th1 dominant immune response and resulted in tumor regression in all 8/8 mice; (ii) the IL-18 antitumor effect was significantly decreased in mice depleted of either the CD4(+), or CD8(+), or NK cell subset, respectively but was completely abrogated in mice depleted of both CD4(+) and CD8(+) T cells; (iii) in vivo neutralization of IFN-gamma was accompanied by the growth of J558/IL-18 tumor in all the mice; and (iv) the J558/IL-18 tumor regression further induced protective immunity against a subsequent challenge by the parental J558 tumor, which is mediated by CD8(+) T cells as examined in the cytotoxicity assay in vitro and in the animal study in vivo. Taken together, our findings indicate that: (i) IL-18 can induce antitumor immune responses mediated by both CD4(+)/CD8(+) T cells and NK cells; and (ii) it is associated with IFN-gamma production. This study thus highlights the potential utility of IL-18 as an antitumor agent, a role that it can fulfil alone or in combination with other immunomodulatory cytokines such as IL-12.     

Synergistic Suppressive Effect of Double Transfection of Tumor Necrosis Factor-α and Interleukin 12 Genes on Tumorigenicity of Meth-A Cells

Tumor necrosis factor-α(TNF-α) and interleukin 12 (IL-12), both potent antitumor cytokines, are known to be involved in the host's antitumor immune surveillance in tumor bearers, via different mechanisms. The former enhances the activities of dendritic cells, natural killer/lymphocyteactivated killer (NK/LAK) and cytotoxic T lymphocyte (CTL), while the latter induces Th1-type cellular immunity and enhances the activities of natural killer T (NKT), NK/LAK and CTL. In the present study, in the expectation of synergistic actions of these cytokines in stimulating the host's immune responses, we investigated the feasibility of a cancer vaccine involving double transfection with both genes in a murine model. The expression of major histocompatibility complex (MHC) class I, class II and B7.1 on the surface of the double transfectants was enhanced as revealed by FACS analysis. A significant decrease in tumorigenicity was observed in mice inoculated with the double transfectants. Cytotoxicity assay revealed that the activities of NK/LAK and CTL from spleens of mice bearing the double transfectants were enhanced. The induction of tumor-specific immunity was confirmed by rechallenge with parental Meth-A cells in mice that had rejected the double transfectants. Thus, double transfection of TNF-α and IL-12 genes was considered to bring about synergistic suppressive effects on the tumorigenicity of transfectants through the activation of killer cells by produced cytokines and the enhancement of expression of MHC class I, II and B7.1 molecules.     

The boosting effect of co-transduction with cytokine genes on cancer vaccine therapy using genetically modified dendritic cells expressing tumor-associated antigen

The T-helper 1 (Th1) immune reaction is most important in dendritic cell (DC)-based immunotherapy. Interleukin 12 (IL-12) and granulocyte macrophage colony-stimulating factor (GM-CSF) play a pivotal role in inducing Th1 and cytotoxic T lymphocyte (CTL) responses. In this study, DCs expressing the natural tumor antigen gp70 of BALB/c-derived CT26 were adenovirally transduced with the IL-12 gene and/or GM-CSF gene, and it was examined whether vaccinations using these genetically engineered DCs can induce strong therapeutic antitumor immunity. Mice were immunized once by subcutaneous (s.c.) injection with genetically modified DCs. The cytotoxic activity of splenocytes against CT26 was assayed in a 51Cr-release assay 14 days after immunization. The therapeutic efficacy of the vaccination was examined in s.c. tumor models. The cytotoxic activity of CTLs against CT26 in mice immunized with DCs expressing gp70 (DC-AxCAgp70) was significantly augmented by co-transduction with the GM-CSF/IL-12 gene (p<0.0001) and remarkably reduced by the depletion of CD4+ or CD8+ cells (p<0.01). The cytotoxic activity against CT26 of the plain spleen cells in mice immunized with DC-AxCAgp70/GM-CSF/IL-12 was significantly higher than that in mice immunized with DC-AxCAgp70 (p<0.0001), and this activity decreased to almost 50% upon the depletion of NK cells. Vaccinations using DC-AxCAgp70/GM-CSF/IL-12 or DC-AxCAgp70/IL-12 could elicit potent therapeutic immunity in s.c. tumor models; tumor-free mice were observed in these vaccination groups. However, there was no significant difference between these two groups. A vaccination therapy using DCs co-transduced with the TAA gene and Th 1-type cytokine genes, especially the IL-12 gene, is ideal for immunotherapy in terms of the activation of DCs, NK cells, CD4+ T cells and CD8+ T cells, and may be useful in the clinical application of a cancer vaccine therapy.     

Synergistic suppressive effect of double transfection of tumor necrosis factor-alpha and interleukin 12 genes on tumorigenicity of Meth-A cells.

Tumor necrosis factor-alpha (TNF-alpha) and interleukin 12 (IL-12), both potent antitumor cytokines, are known to be involved in the host's antitumor immune surveillance in tumor bearers, via different mechanisms. The former enhances the activities of dendritic cells, natural killer / lymphocyte-activated killer (NK / LAK) and cytotoxic T lymphocyte (CTL), while the latter induces Th1-type cellular immunity and enhances the activities of natural killer T (NKT), NK / LAK and CTL. In the present study, in the expectation of synergistic actions of these cytokines in stimulating the host's immune responses, we investigated the feasibility of a cancer vaccine involving double transfection with both genes in a murine model. The expression of major histocompatibility complex (MHC) class I, class II and B7.1 on the surface of the double transfectants was enhanced as revealed by FACS analysis. A significant decrease in tumorigenicity was observed in mice inoculated with the double transfectants. Cytotoxicity assay revealed that the activities of NK / LAK and CTL from spleens of mice bearing the double transfectants were enhanced. The induction of tumor-specific immunity was confirmed by rechallenge with parental Meth-A cells in mice that had rejected the double transfectants. Thus, double transfection of TNF-alpha and IL-12 genes was considered to bring about synergistic suppressive effects on the tumorigenicity of transfectants through the activation of killer cells by produced cytokines and the enhancement of expression of MHC class I, II and B7.1 molecules.     

Synergistic anti-tumor effects with co-expression of GM-CSF and IFN-γ in murine tumors

We explored the potential therapeutic benefit of introducing GM-CSF, IFN-γ or a combination of both factors into CT26 tumor cells. CT26 cells secreting either GM-CSF or IFN-γ exhibited delayed tumorigenicity; however, cells expressing both GM-CSF and IFN-γ did not form tumors. Even when wild type CT26 cells were introduced into a distant site of mice that had been inoculated with CT26/GM-CSF/IFN-γ cells, no tumors were generated. Furthermore, when we injected GM-CSF + IFN-γ cells into animals bearing established tumors, the tumors were either rejected or their development was delayed, suggesting that synergistic effects were induced against these tumors via a systemic immune response. Histopathological examination of the tumors injected with cells expressing GM-CSF and IFN-γ combined showed necrosis and few signs of malignancy. The growth of tumors from mice treated with CT26/GM-CSF/IFN-γ cells exhibited a delay in tumor formation and no effects were seen in athymic nude mice, which are deficient in T lymphocytes, or in splenectomized nude mice, which are deficient in natural killer (NK) cells, respectively. Our data indicate a dual role for T and NK cells in mediating the anti-tumor activity of this therapy. Our results suggest that transduction of tumor cells with both GM-CSF + IFN-γ results in a powerful synergistic effect of the 2 cytokines that is of greater therapeutic benefit than transduction with either cytokine alone. Int. J. Cancer 77:907–912, 1998.© 1998 Wiley-Liss, Inc.     

NK cells mediate the anti-tumor effects of E1-deleted, type 5 adenovirus in a human tumor xenograft model

SCH58500 (ACN53) is a recombinant adenovirus expressing human p53 for gene therapy of cancer. In preclinical studies, SCH58500 has shown efficacy against many tumor-types with non-functional p53. This activity arises from both p53-mediated and adenovirus vector-mediated mechanisms. The importance of NK cells for adenovirus-mediated tumor suppression after intratumoral dosing was demonstrated using MDA-MB-231 human breast cancer xenografts in scid (defective T and B cell response) and scid-beige (defective T, B, and NK cell response) mice. There was no adenovirus vector-mediated anti-tumor activity in scid-beige mice. Dexamethasone (Dex) is a potent suppressor of the cellular immune response to recombinant adenovirus in mice and rats. Dex abolished growth suppression caused by adenovirus vector, but did not interfere with the anti-tumor efficacy of p53. Supression of NK cell activity in scid mice using intravenous administration of a neutralizing antibody had the same effect as Dex. These data support a role for NK cells in adenovirus vector-mediated anti-tumor efficacy.     

腺病毒介导的IL—2基因及B7—1基因联合转染G422细胞致瘤原性和免疫原性的变化

目的研究联合细胞因子基因转染的D422胶质母细胞瘤细胞体内致瘤原性和免疫原性的变化,为胶质瘤的免疫基因治疗打下基础.方法IL-2基因和B7-1基因转染的G422细胞1×105皮下和脑内接种,观察肿瘤生长速度和荷瘤小鼠的存活期,2周取脾脏,检测NK、LAK和CTL的杀伤活性.结果IL-2和B7-1基因联合转染的G422细胞,皮下接种后肿瘤生长明显减慢,脑内接种动物存活期明显延长,NK、LAK和CTL的杀伤活性增强.结论IL-2基因和B7-1基因联合转染的G422细胞,致瘤原性下降,免疫原性增强,能有效激活机体特异性与非特异性抗肿瘤免疫反应.     

UV irradiation of immunized mice induces type 1 regulatory T cells that suppress tumor antigen specific cytotoxic T lymphocyte responses

We previously showed that exposure to UV radiation after immunization suppresses Th1 and Th2 immune responses, leading to impaired Ab and allo-immune responses, but the impact of UV radiation after immunization on anti-tumor immune responses mediated by tumor-specific CD8(+) T cell responses remains less clear. Furthermore, the exact phenotypic and functional characteristics of regulatory T cell population responsible for the UV-induced immunosuppression still remain elusive. Using the MBL-2 lymphoma cell line engineered to express OVA as a surrogate tumor Ag, here we demonstrate that UV irradiation after tumor Ag-immunization suppresses the anti-tumor immune response in a manner dependent on the immunizing Ag. This suppression was mediated by interleukin (IL)-10 released from CD4(+) CD25(+) T cells, by which impaired the induction of cytotoxic T lymphocytes (CTL) able to kill Ag-expressing tumor cells. In addition, we generated a panel of T cell clones from UV-irradiated and non-irradiated mice, and all of the clones derived from UV-irradiated mice had a Tr1-type regulatory T cell phenotype with expression of IL-10 and c-Maf, but not Foxp3. These Tr1-type regulatory T cell clones suppressed tumor rejection in vivo as well as Th cell activation in vitro in an IL-10 dependent manner. Given that suppression of Ag-specific CTL responses can be induced in Ag-sensitized mice by UV irradiation, our results may imply that exposure to UV radiation during premalignant stage induces tumor-Ag specific Tr1 cells that mediate tumor-Ag specific immune suppression resulting in the promotion of tumor progression.     

Overexpression of interleukin-15 in vivo enhances antitumor activity against MHC class I-negative and -positive malignant melanoma through augmented NK activity and cytotoxic T-cell response

Interleukin (IL)-15, a pleiotropic cytokine, is involved in the development and maintenance of NK cells and memory CD8+ T cells. We examined the effects of in vivo overexpression of IL-15 on protection against 2 types of murine B16 melanoma lines, MHC class I-negative B16.44 and MHC class I-positive B16F10 cells, using IL-15 transgenic (Tg) mice that we have recently constructed. The tumor growth was severely retarded in IL-15 Tg mice after subcutaneous (s.c.) inoculation with B16.44 or B16F10 cells. IL-15 Tg mice showed an augmented NK cell activity against B16.44 cells, and in vivo depletion of NK cells by anti-asialoGM1 Ab treatment abrogated the antitumor activity in IL-15 Tg mice. On the other hand, IL-15 Tg mice inoculated with B16F10 cells developed a significant level of CTL response against B16F10 cells, and in vivo depletion of CD8+ T cells by anti-CD8 MAb treatment abrogated the antitumor activity. Thus, overexpression of IL-15 augmented antitumor activity against different tumors via augmentation of different antitumor mechanisms. These results suggest a possible therapeutic application of IL-15 for human neoplasms expressing a wide range of MHC class molecules.