Prostate cancer cell proliferation in vitro is modulated by antibodies against glucose-regulated protein 78 isolated from patient serum
Prostate cancer cell proliferation in vitro is modulated by antibodies against glucose-regulated protein 78 isolated from patient serum
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DOI：
10.1158/0008-5472.can-06-1721
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发表时间：
2006-12-01
期刊：
影响因子：
11.2
通讯作者：
Pizzo, Salvatore V.
中科院分区：
文献类型：
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作者：
Gonzalez-Gronow, Mario;Cuchacovich, Miguel;Pizzo, Salvatore V.
针对葡萄糖调节蛋白78 kDa（GRP 78）的循环自身抗体在前列腺癌患者中以高水平存在，并且是侵袭性肿瘤行为的生物标志物。我们纯化了抗GRP 78 IgG，并检测了它们对I-LN、PC-3、DU 145和LnCap人前列腺癌细胞的作用。我们还评估了其对乳腺癌MDA-MB 231和黑色素瘤DM 413细胞系的作用。抗GRP 78抗体仅与表面上表达GRP 78的细胞结合，结合到也被其生理激动剂活化的α（2）-巨球蛋白（α M-2*）识别的位点。该抗体对肽具有完全特异性，包括一级氨基酸序列CNVKSDKSC，其含有模拟GRP 78中表位的三级结构基序。三级结构分析表明，线性GRP 78一级氨基酸序列LIGRTWNDPSVQQDIKFL（Leu（98）-Leu（115））作为推定的结合位点，含有上述三级结构排列，这是实验证实的。来自前列腺癌患者的抗GRP 78抗体几乎专门识别该表位。我们生产了针对这两种肽的动物抗体，它们能够模拟人类抗体的作用。我们的实验还表明该表位具有高度免疫原性，从而解释了在人类中观察到的针对GRP 78中该表位的免疫应答的特异性。使用I-LN细胞作为模型，我们表明从这些患者的血清中纯化的抗GRP 78 IgG模拟由α M-2* 通过共同受体GRP 78诱导的促增殖作用。此外，增加浓度的人抗GRP 78 IgG显示出对肿瘤坏死因子α诱导的细胞凋亡的剂量依赖性保护作用。
Circulating autoantibodies against the glucose-regulated protein of 78 kDa (GRP78) are present at high levels in prostate cancer patients and are a biomarker of aggressive tumor behavior. We purified the anti-GRP78 IgGs and examined their effect on I-LN, PC-3, DU145, and LnCap human prostate cancer cells. We also evaluated its effects on the breast cancer MDA-MB231 and melanoma DM413 cell lines. The anti-GRP78 antibody binds only to cells expressing GRP78 on the surface, to a site also recognized by its physiologic agonist, activated alpha(2)-macroglobulin (alpha M-2*). This antibody is completely specific for a peptide, including the primary amino acid sequence CNVKSDKSC, which contains a tertiary structural motif mimicking an epitope in GRP78. Tertiary structual analysis suggested the linear GRP78 primary amino acid sequence LIGRTWNDPSVQQDIKFL (Leu(98)-Leu(115)) as the putative binding site, containing the tertiary structual arrangement described above, which was confirmed experimentally. The anti-GRP78 antibodies from prostate cancer patients recognize almost exclusively this epitope. We produced animal antibodies against both these peptides, and they are able to mimic the effects of the human antibody. Our experiments also suggest this epitope as highly immunogenic, thereby explaining the specificity of the immune response against this epitope in GRP78, observed in humans. Using I-LN cells as a model, we show that anti-GRP78 IgG purified from the sera of these patients mimics the proproliferative effects induced by alpha M-2* via the common receptor, GRP78. Furthermore, increasing concentrations of human anti-GRP78 IgG show a dose-dependent protective effect on apoptosis induced by tumor necrosis factor alpha.