Xing Xiaoming, Lai Maode, Wang Yinghong, Xu Enping, Huang Qiong
Department of Pathology and Pathophysiology, Center for Environmental Genomics, School of Medicine, Zhejiang University, Hangzhou 310031, PR China.
Clin Chim Acta. 2006 Feb;364(1-2):308-15. doi: 10.1016/j.cca.2005.07.016. Epub 2005 Sep 21.
The 78 kDa glucose-regulated protein (GRP78) has been implicated in the development of tumorigenicity, drug resistance, and cytotoxic immunology. We investigated the expression pattern of GRP78 at the protein and mRNA level in human colon carcinoma, colon adenoma and normal colon mucosa.
Two-dimensional (2-D) gel electrophoresis, electrospray ionization tandem mass spectrometry, immunoblot analysis, reverse-transcriptase PCR and immunohistochemistry were used on colon normal and cancer tissues.
Comparative 2-D gel electrophoresis of individual-matched colon normal and cancer tissues revealed 15 protein spots with concordantly increased and 20 protein spots with concordantly decreased intensity in tumor tissue. Fourteen of these proteins were identified by tandem mass spectrometry. One of the identified proteins, GRP78, exhibited a marked up-regulation in colon cancer tissue. This result was further confirmed by Western blot and immunohistochemical analysis. Immunohistochemistry also revealed increased cytoplasmic GRP78 expression with progression along the normal tissue-adenoma-carcinoma sequence. However, to our surprise, there was essentially no difference in the relative mRNA expression levels of GRP78 between normal and colon tumors.
Our findings indicate that overexpression of GRP78 protein may be an important biomarker for malignant transformation, and increased expression might be related with the posttranscriptional regulation of GRP78 in tumor tissues.
78 kDa葡萄糖调节蛋白（GRP78）与肿瘤发生、耐药性及细胞毒性免疫相关。我们研究了GRP78在人结肠癌、结肠腺瘤及正常结肠黏膜中的蛋白和mRNA水平表达模式。
对结肠正常组织和癌组织进行二维（2-D）凝胶电泳、电喷雾电离串联质谱分析、免疫印迹分析、逆转录聚合酶链反应及免疫组织化学检测。
对个体匹配的结肠正常组织和癌组织进行比较二维凝胶电泳，发现肿瘤组织中有15个蛋白点强度一致增加，20个蛋白点强度一致降低。其中14种蛋白通过串联质谱分析得以鉴定。所鉴定的蛋白之一GRP78在结肠癌组织中显著上调。这一结果通过蛋白质印迹法和免疫组织化学分析得到进一步证实。免疫组织化学还显示，随着正常组织-腺瘤-癌序列进展，细胞质中GRP78表达增加。然而，令我们惊讶的是，正常组织与结肠肿瘤之间GRP78的相对mRNA表达水平基本没有差异。
我们的研究结果表明，GRP78蛋白的过表达可能是恶性转化的一个重要生物标志物，其表达增加可能与肿瘤组织中GRP78的转录后调控有关。
