Interleukin-12 cDNA skin transfection potentiates human papillomavirus E6 DNA vaccine-induced antitumor immune response.
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Human papillomaviruses are associated with >90% of all cases of uterine cervical tumors. The E6 and E7 oncoproteins of human papillomavirus are potentially ideal targets of immune therapy for cervical cancer, because their expression is necessary for cellular transformation. Although both E6 and E7 proteins contain numerous predicted cytotoxic T lymphocyte (CTL) epitopes that are capable of binding to human leukocyte antigens, the majority of earlier in vivo tumor rejection studies have focused on E7. We show here that gene gun-mediated skin transfection of plasmid vector encoding the nontransforming, amino-terminal half of E6 resulted in the induction of E6-specific CTL activity and tumor rejection in a murine model. The use of recombinant murine interleukin-12 (rmIL-12) as a vaccine adjuvant has been shown to result in both an enhancement and suppression of immune responses, depending upon the doses of rmIL-12 and the experimental systems used. We demonstrate here that local expression of transgenic mIL-12 at the E6 DNA vaccination site potentiated E6-specific CTL responses and increased vaccine-induced antitumor therapeutic efficacy. Our results indicate that transfection of the mIL-12 gene at the vaccination site may represent an attractive adjuvant for cancer gene immunotherapy. (+info)
Combination immunotherapy of B16 melanoma using anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and granulocyte/macrophage colony-stimulating factor (GM-CSF)-producing vaccines induces rejection of subcutaneous and metastatic tumors accompanied by autoimmune depigmentation.
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We examined the effectiveness of cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) blockade, alone or in combination with a granulocyte/macrophage colony-stimulating factor (GM-CSF)-expressing tumor cell vaccine, on rejection of the highly tumorigenic, poorly immunogenic murine melanoma B16-BL6. Recently established tumors could be eradicated in 80% (68/85) of the cases using combination treatment, whereas each treatment by itself showed little or no effect. Tumor rejection was dependent on CD8(+) and NK1.1(+) cells but occurred irrespective of the presence of CD4(+) T cells. Mice surviving a primary challenge rejected a secondary challenge with B16-BL6 or the parental B16-F0 line. The same treatment regimen was found to be therapeutically effective against outgrowth of preestablished B16-F10 lung metastases, inducing long-term survival. Of all mice surviving B16-BL6 or B16-F10 tumors after combination treatment, 56% (38/68) developed depigmentation, starting at the site of vaccination or challenge and in most cases progressing to distant locations. Depigmentation was found to occur in CD4-depleted mice, strongly suggesting that the effect was mediated by CTLs. This study shows that CTLA-4 blockade provides a powerful tool to enhance T cell activation and memory against a poorly immunogenic spontaneous murine tumor and that this may involve recruitment of autoreactive T cells. (+info)
Effective cytokine gene therapy against an intracranial glioma using a retrovirally transduced IL-4 plus HSVtk tumor vaccine.
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To explore the potential for molecular immunotherapies in the treatment of malignant gliomas, we evaluated the efficacy of subcutaneous tumor cell vaccines in the treatment of intracranial 9L tumors, using 9L gliosarcoma cell lines stably transduced with the murine interleukin-4 cDNA (9L-IL4), the herpes simplex virus-thymidine kinase cDNA (9L-Tk) or both (9L-IL4-Tk). The expression of multiple genes from a single transcript was achieved by incorporating internal ribosomal entry site (IRES) cassettes in the retroviral constructs. Subcutaneous immunization of rats with nonirradiated 9L-IL4 cells or 9L-IL4-Tk cells followed by treatment with ganciclovir (GCV) completely protected the animals from a subsequent intracranial challenge with wild-type 9L cells. In contrast, only 50% of animals immunized with 9L-Tk cells and 0% of 9L-neo immunized animals rejected the same challenge with wild-type 9L. More importantly, treatment of established (day 3) intracranial 9L tumors with genetically engineered tumor cells resulted in long-term survival (> 100 days) for 25-43% of 9L-IL4-Tk immunized animals and for 27% of nonirradiated 9L-IL4 immunized animals. In striking contrast, no 9L-Tk, 9L-neo or irradiated 9L-IL4 immunized animals survived for more than 33 days. As a marker of a cellular immune response, splenocytes from nonirradiated 9L-IL4, 9L-Tk or 9L-IL4-Tk immunized animals produced interferon-gamma (IFN-gamma) in greater amounts than those from 9L-neo immunized or Hank's balanced salts solution (HBSS) treated animals when stimulated with wild-type 9L in vitro. Our findings support the use of tumor cell vaccines expressing the IL-4 and HSVtk genes for the treatment of malignant gliomas. (+info)
Human papillomavirus type 16 E7 DNA vaccine: mutation in the open reading frame of E7 enhances specific cytotoxic T-lymphocyte induction and antitumor activity.
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A human papillomavirus type 16 E7 DNA vaccine with the open reading frame encoding mutations in two zinc-binding motifs expressed a rapidly degraded E7 protein. This vaccine induced a significantly stronger E7-specific cytotoxic T-lymphocyte response and better tumor protection in mice than did a wild-type E7 DNA vaccine expressing a stable E7 protein. (+info)
IL-4-transduced tumor cell vaccine induces immunoregulatory type 2 CD8 T lymphocytes that cure lung metastases upon adoptive transfer.
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Vaccinations with tumor cells engineered to produce IL-4 prolonged survival and cured 30% of mice bearing pulmonary metastases, an effect abrogated by in vivo depletion of T cells. Vaccination induced type 2 T cell polarization in both CD4 and CD8 T lymphocyte subsets. We focused on the antitumor activity exerted by type 2 CD8+ T cells (Tc2) activated by IL-4 tumor cell vaccination. Tc2 lymphocytes lacked in vitro tumor cytotoxicity, but released IL-4 upon stimulation with tumor cells, as shown by limiting dilution analysis of the frequencies of tumor-specific pCTL and of CD8 cells producing the cytokine. In vivo fresh purified CD8+ T lymphocytes from IL-4-vaccinated mice eliminated 80-100% of lung metastases when transferred into tumor-bearing mice. CD8+ lymphocytes from IL-4-vaccinated IFN-gamma knockout (KO), but not from IL-4 KO, mice cured lung metastases, thus indicating that IL-4 produced by Tc2 cells was instrumental for tumor rejection. The antitumor effect of adoptively transferred Tc2 lymphocytes needed host CD8 T cells and AsGM1 leukocyte populations, and partially granulocytes. These data indicate that Tc2 CD8+ T cells exert immunoregulatory functions and induce tumor rejection through the cooperation of bystander lymphoid effector cells. Tumor eradication is thus not restricted to a type 1 response, but can also be mediated by a type 2 biased T cell response. (+info)
Dendritic cells transduced with wild-type p53 gene elicit potent anti-tumour immune responses.
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In this study we have tested the concept of using wild-type p53 gene for immunotherapy of cancer. Dendritic cells (DC) were transduced with a human wild-type p53 containing recombinant adenovirus (Ad-p53). About a half of DC transduced with this virus expressed p53 protein by FACS analysis 48 h after infection. Mice immunized twice with Ad-p53 DC developed substantial cytotoxic T lymphocyte (CTL) responses against tumour cells expressing wild-type and different mutant human and murine p53 genes. Very low CTL responses were observed against target cells infected with control adenovirus (Ad-c). Immunization with Ad-p53 provided complete tumour protection in 85% of mice challenged with tumour cells expressing human mutant p53 and in 72.7% of mice challenged with tumour cells with murine mutant p53. Treatment with Ad-p53-transduced DC significantly slowed the growth of established tumours. Thus, DC transduced with wild-type p53 may be a promising new tool for the immunotherapy of cancer. (+info)
Augmentation of local antitumor immunity in the liver by tumor vaccine modified to secrete murine interleukin 12.
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Minimal residual lesions have been a major problem in surgical management of cancer. We transfected M5076 with murine IL-12 gene by a retroviral vector, established a stable transfectant secreting IL-12 and investigated its antitumor effects on a spontaneous liver metastasis murine model of M5076 reticulum cell sarcoma. Subcutaneous vaccination of the irradiated transfectant into the remote skin following the amputation of the tumor-bearing limb improved survival when compared with the vaccination of irradiated parental cells (control). Cytotoxic activities against parental M5076 were significantly stronger in the hepatic lymphocytes from the mice vaccinated with the IL-12 transfectant than those from the control. IFN-gamma production of hepatic lymphocytes when they were cocultured with the parental cells was significantly augmented in mice vaccinated with the IL-12 transfectant compared with the control. On the other hand, both cytotoxic activity and IFN-gamma production of spleen cells in the M5076-vaccinated and transfectant-vaccinated mice were at similar levels. Immunophenotypic analysis revealed the selective increase of CD3+NK1+ population in the liver from the transfectant-vaccinated mice. These results suggest that tumor vaccines genetically modified to secrete IL-12 continuously at a relatively low level preferentially augment local antitumor activity in the liver rather than systemic immune responses. This strategy warrants further investigation as an adjuvant modality in the management of postoperative residual tumors. (+info)
Therapy of established tumour with a hybrid cellular vaccine generated by using granulocyte-macrophage colony-stimulating factor genetically modified dendritic cells.
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Dendritic cells (DCs) are the most powerful of all antigen-presenting cells and play a critical role in the induction of primary immune responses. DC-based vaccination represents a potentially powerful strategy for cancer immunotherapy. In this study, a new approach for a DC-based melanoma vaccine was described. Splenic DCs from C57BL/6 mice were fused with B16 melanoma cells, and the resultant B16/DC hybrid cells expressed major histocompatibility complex (MHC) molecules - B7 as well as the B16 tumour marker M562 - which were enriched by Ia-mediated positive selection with a MiniMACS column. The fusion rates were 12.7-26.8%. To generate hybrid tumour vaccines with potentially greater potent therapeutic efficacy, we genetically engineered DCs with granulocyte-macrophage colony-stimulating factor (GM-CSF) prior to cell fusion. Recombinant adenovirus vector was used to mediate gene transfer into DCs with high efficiency and DCs expressed GM-CSF at 96-138 ng/105 cells/ml 24 hr after GM-CSF gene transfer. GM-CSF gene-modified DCs (DC.GM) exhibited higher expression of B7 and co-stimulatory capacity in mixed lymphocyte reaction (MLR). Fusion of DC.GM with B16 cells generated B16/DC.GM hybrid cells secreting GM-CSF at 59-63 ng/105 cells/ml. Immunization of C57BL/6 mice with the B16/DC hybrid vaccine elicited a specific cytotoxic T-lymphocyte (CTL) response and protected the immunized mice from B16 tumour challenge, reduced pulmonary metastases and extended the survival of B16 tumour-bearing mice. The B16/DC.GM hybrid vaccine was able to induce a CTL response and protective immunity more potently and tended to be therapeutically more efficacious than the B16/DC vaccine. In vivo depletion of T-cell subsets demonstrated that both CD8+ and CD4+ T cells were essential for the therapeutic effects of B16/DC and B16/DC.GM hybrid vaccines. Additionally, other non-specific effector cells may also contribute to tumour rejection induced by the B16/DC.GM hybrid vaccine. These data indicate that a DC-based hybrid tumour vaccine may be an attractive strategy for cancer immunotherapy, and that GM-CSF gene-modified DCs may lead to the generation of hybrid vaccines with potentially increased therapeutic efficacy. (+info)