Lladser Alvaro, Párraga Mario, Quevedo Licarallén, Carmen Molina Maria, Silva Soledad, Ferreira Arturo, Billetta Rosario, G Quest Andrew F
FONDAP Center for Molecular Studies of the Cell (CEMC), University of Chile, Av. Independencia 1027, Independencia, Santiago, Chile.
Immunobiology. 2006;211(1-2):11-27. doi: 10.1016/j.imbio.2005.08.002. Epub 2005 Dec 27.
Survivin, a 16.5 kDa tumor associated antigen, is the smallest member of the inhibitor of apoptosis family that is abundantly expressed during development but essentially absent in normal adult tissues. Interestingly, survivin expression is up-regulated in virtually all types of cancers studied, as well as in vascular endothelial cells during tumor associated angiogenesis. Survivin links apoptosis to cell cycle progression and plays a pivotal role in regulation of cell proliferation. These characteristics make survivin a potentially promising generic target for cancer immunotherapy. Hence, a genetic immunization strategy to induce tumor-specific immune responses against human survivin in a pre-clinical animal model was developed. In initial studies, BALB/c mice were immunized by intramuscular injection with DNA coding for human survivin (pcDNA3.1/hSurv). In addition, a construct encoding a secreted version of survivin (pSecTag2B/hSurv) was designed. A plasmid coding for murine granulocyte-macrophage colony-stimulating factor (GM-CSF) was co-injected in both cases as a molecular adjuvant. Expression of survivin following transfection in mouse cells was corroborated. Humoral responses against human survivin were detected in mice sera using two immunization protocols (injections at 2- or 3-week intervals). The humoral response was markedly improved by secretion of survivin and co-expression of GM-CSF. The predominant antibody subclass detected in responsive mice was IgG2a, suggesting that a Th1-CD4+ cellular response had been induced. Furthermore, DNA immunization with survivin encoding vectors generated an effective CD8+ T cell response measured as an increase of cytotoxic Interferon-gamma (IFN-gamma) secreting CD8+ T cells. In conclusion, intramuscular genetic immunization of mice with human survivin encoding plasmids induced a survivin-specific humoral as well as cellular immune response in recipient mice. Secretion of survivin and co-injection of GM-CSF as a genetic adjuvant appear to be more important in generating an humoral than a cellular immune response.
存活素是一种16.5 kDa的肿瘤相关抗原，是凋亡抑制蛋白家族中最小的成员，在发育过程中大量表达，但在正常成人组织中基本不存在。有趣的是，在几乎所有研究的癌症类型以及肿瘤相关血管生成过程中的血管内皮细胞中，存活素的表达都上调。存活素将细胞凋亡与细胞周期进程联系起来，并在细胞增殖调控中起关键作用。这些特性使存活素成为癌症免疫治疗中一个潜在的有前景的通用靶点。因此，开发了一种在临床前动物模型中诱导针对人存活素的肿瘤特异性免疫反应的基因免疫策略。在初步研究中，通过肌肉注射编码人存活素的DNA（pcDNA3.1/hSurv）对BALB/c小鼠进行免疫。此外，设计了一种编码分泌型存活素的构建体（pSecTag2B/hSurv）。在这两种情况下，都共同注射编码小鼠粒细胞-巨噬细胞集落刺激因子（GM-CSF）的质粒作为分子佐剂。证实了转染后小鼠细胞中存活素的表达。使用两种免疫方案（间隔2周或3周注射）在小鼠血清中检测到了针对人存活素的体液反应。存活素的分泌和GM-CSF的共表达显著改善了体液反应。在反应小鼠中检测到的主要抗体亚类是IgG2a，表明诱导了Th1-CD4+细胞反应。此外，用编码存活素的载体进行DNA免疫产生了有效的CD8+ T细胞反应，表现为分泌细胞毒性干扰素-γ（IFN-γ）的CD8+ T细胞增加。总之，用编码人存活素的质粒对小鼠进行肌肉内基因免疫在受体小鼠中诱导了存活素特异性的体液和细胞免疫反应。存活素的分泌和作为基因佐剂共同注射GM-CSF在产生体液免疫反应方面似乎比细胞免疫反应更重要。
