Division of Pharmacoproteomics, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
Jpn J Clin Oncol. 2013 Jun;43(6):669-75. doi: 10.1093/jjco/hyt057. Epub 2013 Apr 25.
Adjuvant treatment with imatinib mesylate is an effective treatment for gastrointestinal stromal tumor. However, 50% of patients with gastrointestinal stromal tumor can be cured by surgery alone; hence, risk stratification for therapy with imatinib mesylate is the next challenge. Previously, using a proteomic approach, we discovered a potential prognostic biomarker for gastrointestinal stromal tumor, pfetin, and immunohistochemically validated its clinical utility using our original monoclonal antibody. In the present study, we examine the usefulness of a commercially available polyclonal antibody against pfetin.
Western blotting and immunohistochemistry were performed using surgical specimens of primary tissues from gastrointestinal stromal tumor patients using a polyclonal antibody against pfetin and our original monoclonal antibody. Formalin-fixed and paraffin-embedded primary tissue sections from 112 gastrointestinal stromal tumor patients were subjected to immunohistochemistry. The immunohistochemistry results were integrated with the clinico-pathological observations.
Western blotting revealed that both antibodies recognized multiple post-translationally modified pfetin isoforms. The immunohistochemical study with the commercial antibody demonstrated that the disease-free survival rate was 88 and 56% for pfetin-positive and pfetin-negative patients, respectively. Univariate and multivariate analyses showed that pfetin expression as measured by the commercial antibody was a significant and independent prognostic factor among the clinico-pathological parameters examined. Of the 112 gastrointestinal stromal tumor cases examined, 13 yielded discordant results between the commercial antibody and our original antibody, and there were no significantly different clinical or pathological factors to account for this discrepancy.
Our observations suggest that the pfetin expression level assessed by the commercial antibody could be a prognostic biomarker in gastrointestinal stromal tumors.
甲磺酸伊马替尼辅助治疗是胃肠道间质瘤的有效治疗方法。然而，50%的胃肠道间质瘤患者可以通过手术单独治愈；因此，伊马替尼治疗的风险分层是下一个挑战。先前，我们使用蛋白质组学方法发现了胃肠道间质瘤的一个潜在预后生物标志物 pfetin，并使用我们原创的单克隆抗体免疫组织化学验证了其临床效用。在本研究中，我们检验了针对 pfetin 的商业可得的多克隆抗体的有用性。
使用针对 pfetin 的多克隆抗体和我们原创的单克隆抗体对胃肠道间质瘤患者的原发组织手术标本进行 Western blot 和免疫组织化学分析。对 112 例胃肠道间质瘤患者的福尔马林固定石蜡包埋的原发组织切片进行免疫组织化学分析。将免疫组织化学结果与临床病理观察相结合。
Western blot 显示两种抗体均识别多种翻译后修饰的 pfetin 同工型。使用商业抗体的免疫组织化学研究表明，pfetin 阳性和 pfetin 阴性患者的无病生存率分别为 88%和 56%。单因素和多因素分析表明，在检查的临床病理参数中，用商业抗体测量的 pfetin 表达是一个显著且独立的预后因素。在检查的 112 例胃肠道间质瘤病例中，商业抗体和我们原创抗体之间有 13 例存在不一致的结果，没有明显不同的临床或病理因素可以解释这种差异。
我们的观察结果表明，商业抗体评估的 pfetin 表达水平可能是胃肠道间质瘤的预后生物标志物。
