An experimental study on antitumor immuno-gene therapy using dendritic cells genetically modified to express the tumor antigen gene and cytokine gene

在本研究中，我们检查了使用树突状细胞（DC）基因工程表达肿瘤抗原的免疫治疗的疗效，比较使用DC脉冲与肿瘤抗原肽在CT 26肿瘤模型中的免疫治疗。同时将肿瘤抗原基因和GM-CSF基因共转导DCs，观察其对肿瘤疫苗治疗的增强作用。将BALB/c小鼠CT 26的天然肿瘤抗原gp 70基因（DC-AxCAgp 70）腺病毒转导于小鼠骨髓来源的DC，并与小鼠GM-CSF共转导（DC-AxCAgp 70/mGM-CSF）。另一方面，DC用AH-1（DC/AH-1）脉冲，AH-1是gp 70的免疫显性肽。DCs-AxCAgp 70免疫小鼠诱导的细胞毒性T淋巴细胞（CTL）活性（40%）显著高于DC/AH-1免疫小鼠（24%）（E/T：50）。DC-AxCAgp 70/mGM-CSF免疫小鼠，CTL活性明显增强（86%）。在CT 26的皮下肿瘤模型和原位结肠癌模型中，使用DC-AxCAgp 70的疫苗治疗显示出比使用DC/AH-1的疫苗接种更显著的肿瘤生长抑制（p<0.0001），这反映在导致存活期的延长。通过将mGM-CSF基因共转导至DC-AxCAgp 70来增强抗肿瘤应答。腺病毒介导的gp 70基因可诱导DC表面CC趋化因子受体7 mRNA表达，而与mGM-CSF基因共转导可进一步增强DC表面CC趋化因子受体7 mRNA的表达，CC趋化因子受体7 mRNA在DC向淋巴结迁移中起重要作用。相反，在AH-1脉冲的DC中未检测到。这些结果表明，使用同时转导有肿瘤抗原基因和细胞因子基因的DC的疫苗接种可能是治疗性抗肿瘤免疫治疗的更有效的策略。

In present study, we examined therapeutic efficacy of the immunotherapy using dendritic cells (DCs) genetically engineered to express the tumor antigen, comparing to the immunotherapy using DCs pulsed with the tumor antigen peptide in CT26 tumor models. Moreover, DCs were transduced simultaneously with tumor antigen gene and GM-CSF gene, and we assessed the augmenting effect of cotransduction with GM-CSF gene on therapeutic vaccine therapy. Bone marrow-derived murine DCs were adenovirally transduced with natural tumor antigen gp70 gene of BALB/c-derived CT26 (DC-AxCAgp70), and cotransduced with murine GM-CSF (DC-AxCAgp70/mGM-CSF). On the other hand, DCs were pulsed with AH-1 which is immunodominant peptide of the gp70 (DC/AH-1). The cytotoxic T lymphocyte (CTL) activities induced in the mice immunized with DCs-AxCAgp70 showed significantly higher (40%) than that in the mice immunized with DC/AH-1 (24%)(E/T : 50). Furthermore, CTL activities were enhanced in the mice immunized with DC-AxCAgp70/mGM-CSF (86%). In the subcutaneous tumor model and the orthotopic colon cancer model of CT26, the vaccine therapy using DC-AxCAgp70 showed much more remarkable inhibition of tumor growth than the vaccination using DC/AH-1 (p<0.0001), which was reflected in resulting in the prolongation of the survival periods. Antitumor responses were augmented by cotransduction with mGM-CSF gene to DC-AxCAgp70. CC chemokine receptor 7 mRNA expression on DCs, which would play an important role in the migration of DCs to regional lymph nodes was induced by adenoviral transduction with gp70 gene, and more enhanced by cotransduction with mGM-CSF gene. In contrast, it was not detected in AH-1-pulsed DCs. These results suggested that the vaccination using DCs transduced with both the tumor antigen gene and cytokine gene could be a more potent strategy for therapeutic antitumor immunotherapy.