[Show abstract][Hide abstract] ABSTRACT: Although the whole tumor cell vaccine can provide the best source of immunizing antigens, there is still a limitation that most tumors are not naturally immunogenic. Tumor cells genetically modified to secrete immune activating cytokines have been proved to be more immunogenic. IL-18 could augment proliferation of T cells and cytotoxicity of NK cells. GM-CSF could stimulate dendritic cells, macrophages and enhance presentation of tumor antigens. In our study, we used mouse GM-CSF combined with IL-18 to modify Lewis lung cancer LL/2, then investigated whether vaccination could suppress tumor growth and promote survival.
The Lewis lung cancer LL/2 was transfected with co-expressing mouse GM-CSF and IL-18 plasmid by cationic liposome, then irradiated with a sublethal dose X ray (100Gy) to prepare vaccines. Mice were subcutaneously immunized with this inactivated vaccine and then inoculated with autologous LL/2 to estimate the antitumor efficacy.
The studies reported here showed that LL/2 tumor cell vaccine modified by a co-expressing mouse GM-CSF and IL-18 plasmid could significantly inhibit tumor growth and increased survival of the mice bearing LL/2 tumor whether prophylactic or adoptive immunotherapy in vivo. A significant reduction of proliferation and increase of apoptosis were also observed in the tumor treated with vaccine of co-expressing GM-CSF and IL-18. The potent antitumor effect correlated with higher secretion levels of pro-inflammatory cytokines such as IL-18, GM-CSF, interferon-gamma in serum, the proliferation of CD4+IFN-gamma+, CD8+ IFN-gamma+ T lymphocytes in spleen and the infiltration of CD4+, CD8+ T in tumor. Furthermore, the mechanism of tumor-specific immune response was further proved by 51Cr cytotoxicity assay in vitro and depletion of CD4, CD8, NK immune cell subsets in vivo. The results suggested that the antitumor mechanism was mainly depended on CD4+, CD8+T lymphocytes.
These results provide a new insight into therapeutic mechanisms of IL-18 plus GM-CSF modified tumor cell vaccine and provide a potential clinical cancer immunotherapeutic agent for improved antitumor immunity.
[Show abstract][Hide abstract] ABSTRACT: Interleukin-27 (IL-27), a novel IL-6/IL-12 family cytokine, plays an important role in the early regulation of Th1 responses. The cytokine IL-27 can exert a variety of immune-regulatory functions including cytotoxic T lymphocyte (CTL), CD4(+), CD8+ T lymphocytes activation and interferon-γ (IFN-γ) production. In this study, we developed an effective and gene modified tumor cell vaccine. Lewis lung cancer cell LL/2 transfected with the DOTAP:cholesterol cationic liposome could express the mouse IL-27 (mIL-27) gene at a relative high level. The resultant transfectants were then irradiated with X-ray and used as a tumor cell vaccine. This tumor cell vaccine not only contained tumor associated antigen (TAA) of LL/2 cells but also secreted mIL-27 which could induce immune response in mice. The mice vaccinated with LL/2-mIL-27 performed strong tumor inhibiting effect accompanied with a high IFN-γ production. Both CD4+ and CD8+ T lymphocytes were significantly elevated in these mice vaccinated with LL/2-mIL-27 cell vaccine. Moreover, after depletion of CD4+, CD8+ T lymphocytes by injection of antibodies against CD4 and CD8, the vaccinated mice inoculated with autologous LL/2 cells were not protected from tumor challenge. In contrast, vaccinated mice inoculated with autologous LL/2 cells were treated with antibody against natural killer (NK)cells or normal rat IgG still possessed strong antitumor activity. Our data suggested that DOTAP:cholesterol cationic liposome was quite useful in generating an autologous tumor cell vaccine and mIL-27 could be therapeutically used to potentiate the host antitumor immunity.
No preview · Article · Mar 2013 · Molecular Immunology
[Show abstract][Hide abstract] ABSTRACT: Survivin, a member of the inhibitor of apoptosis protein (IAP) family, is abundantly expressed in a variety of cancer cells, including lung cancer cells, resulting in low sensitivity of these cells to various apoptotic stimuli; Cisplatin (CDDP), a commonly used chemotherapeutic agent of several cancers, has a major limitation because of its toxicity at high concentration. In the present study, we constructed a plasmid encoding Survivin shRNA to knockdown survivin with low dose DDP both in vitro and in vivo. The specificity and potency of the shRNA were validated by western blot, flow cytometric and MTT in H292 lung cancers cells. In vivo, therapy experiments were conducted on nude mice bearing H292 xenograft tumors. The Survivin shRNA expression plasmid was administered systemically in combination with low-dose CDDP on a frequent basis. Assessments of angiogenesis, cell proliferation and apoptosis were performed by using immunohistochemistry against CD31, Ki67 and TUNEL assays, respectively. The results revealed that treatment with the Survivin shRNA plus low-dose CDDP reduced volume by approximately 83.13% compared with the blank control (P < 0.01), accompanied with angiogenesis inhibition (p < 0.01), tumor cell proliferation suppression (p < 0.05) and apoptosis induction (p < 0.01). Moreover, combination treatment also significantly reduced the mean tumor volume compared with other treatment alone (p < 0.05). Taken together, our study suggested that silencing of survivin sensitized H292 lung cancer cells to chemotherapy of CDDP, suggesting potential applications of the combined approach in the treatment of lung cancer.
No preview · Article · Aug 2012 · Journal of Biomedical Nanotechnology
[Show abstract][Hide abstract] ABSTRACT: Class A scavenger receptor member 5 (SCARA5) is a new member of the Class A scavenger receptors that has been proposed recently as a novel candidate tumor suppressor gene in human hepatocellular carcinoma. In the present study, we found that SCARA5 expression was frequently downregulated in various cancer cell lines and tumor samples. In addition, upregulation of SCARA5 expression in human cancer cell line (U251) led to a significant decrease in cell proliferation, clone formation, migration, and invasion in vitro. Furthermore, systemic treatment of tumor-bearing mice with SCARA5-cationic liposome complex not only reduced the growth of subcutaneous human glioma tumors, but also markedly suppressed the spontaneous formation of lung metastases. Similar results were obtained in another experiment using mice bearing experimental A549 lung metastases. Compared with the untreated control group, mice treated with SCARA5 exhibited reductions in both spontaneous U251 and experimental A549 lung metastases rates of 77.3% and 70.2%, respectively. Western blot analysis was used to explore the molecular mechanisms involved and revealed that SCARA5 physically associated with focal adhesion kinase. Interestingly, upregulation of SCARA5 inactivated signal transducer and activator of transcription 3, as well as downstream signaling including cyclinB1, cyclinD1, AKT, survivin, matrix metalloproteinase-9 and vascular endothelial growth factor-A. Overall, the findings of the present study provide the first evidence that SCARA5 might be a promising target for the development of new antimetastatic agents for the gene therapy of cancer.