Shebzukhov Yuriy V, Lavrik Inna N, Karbach Julia, Khlgatian Svetlana V, Koroleva Ekaterina P, Belousov Pavel V, Kashkin Kirill N, Knuth Alexander, Jager Elke, Chi Nai-Wen, Kuprash Dmitry V, Nedospasov Sergei A
Department of Molecular Immunology, Belozersky Institute of Physico-Chemical Biology, Moscow State University, Vorobjovy Gory, Moscow 119899, Russia.
Cancer Immunol Immunother. 2008 Jun;57(6):871-81. doi: 10.1007/s00262-007-0423-z. Epub 2007 Nov 20.
Tankyrases 1 and 2 are telomere-associated poly(ADP-ribose) polymerases (PARP) that can positively regulate telomere elongation and interact with multiple cellular proteins. Recent reports implicated tankyrases as tumor antigens and potential targets of anticancer treatment. We examined expression of tankyrases in colon tumors and immune response to these enzymes in patients with different types of cancer.
mRNA and protein expression was evaluated by quantitative real-time RT-PCR and Western blotting, respectively. Humoral immune response to recombinant tankyrases was investigated by modified enzyme-linked immunoassays. Cellular immune response was analysed by ELISPOT and (51)Cr release assays.
We found that both mRNA and protein levels of tankyrase 2 (TNKL) are upregulated in colon tumors. In contrast, protein level of tankyrase 1 (TNKS) is downregulated, while mRNA level shows variable changes. More than a quarter of colon cancer patients develop humoral immune response to at least one of the two tankyrases. In this study we mapped common and unique B-cell epitopes located in different domains of the two proteins. Additionally, we present evidence for T-cell responses both to epitopes that are unique for TNKL and to those shared between TNKL and TNKS.
Our study favors a biomarker usage of antibody response to tankyrases. Spontaneous CD8(+) T-cell responses to these enzymes are rare and further investigation is needed to evaluate tankyrases as potential targets for cancer immunotherapy.
端锚聚合酶1和2是与端粒相关的聚（ADP - 核糖）聚合酶（PARP），可正向调节端粒延长并与多种细胞蛋白相互作用。最近的报道表明端锚聚合酶是肿瘤抗原和抗癌治疗的潜在靶点。我们研究了端锚聚合酶在结肠肿瘤中的表达以及不同类型癌症患者对这些酶的免疫反应。
分别通过定量实时RT - PCR和蛋白质印迹法评估mRNA和蛋白质表达。通过改良的酶联免疫测定法研究对重组端锚聚合酶的体液免疫反应。通过ELISPOT和（51）Cr释放试验分析细胞免疫反应。
我们发现结肠肿瘤中端锚聚合酶2（TNKL）的mRNA和蛋白质水平均上调。相比之下，端锚聚合酶1（TNKS）的蛋白质水平下调，而mRNA水平呈现出可变变化。超过四分之一的结肠癌患者对两种端锚聚合酶中的至少一种产生体液免疫反应。在本研究中，我们绘制了位于这两种蛋白质不同结构域的共同和独特的B细胞表位。此外，我们提供了针对TNKL独特表位以及TNKL和TNKS共享表位的T细胞反应的证据。
我们的研究支持将针对端锚聚合酶的抗体反应用作生物标志物。对这些酶的自发CD8（+）T细胞反应很少见，需要进一步研究以评估端锚聚合酶作为癌症免疫治疗的潜在靶点。
