SELENBP1在结直肠癌中的表达及其与肿瘤分化的关系

目的：通过蛋白质组学技术筛选出结直肠癌（CRC）组织中差异表达最显著的蛋白,并探讨其与CRC疾病特征的关系。方法：收集83例CRC患者手术标本,包括患者的CRC组织,正常大肠黏膜组织,转移的淋巴结以及部分患者同时长有的大肠良性息肉。用二维差异凝胶电泳（2D DIGE）及基质辅助激光解析飞行时间质谱（MALDI-TOF-MS）对新鲜的CRC与正常黏膜组织以行蛋白质组学分析。找出兴趣蛋白后,用Western blot法在新鲜的CRC与正常黏膜组织,以及不同的CRC细胞株中验证;用免疫组化检测石蜡包埋的CRC、正常黏膜、良性息肉和转移淋巴结组织中该蛋白的表达。用Western blot法检测CRC细胞株在丁酸钠（NaB）诱导分化后该蛋白的表达改变。结果：2D-DIGE分析和MALDI-TOF-MS鉴定结果显示,CRC组织中硒结合蛋白1（SELENBP1）表达丰度比正常黏膜组织明显降低2.54倍（P<0.01）。Western blot示,CRC组织中SELENBP1的表达水平明显低于其配对的正常黏膜组织[（0.76±0.37） vs. (1.46±0.56）]（P<0.001）,SELENBP1的表达在CRC细胞株中普遍降低。免疫组化示,SELENBP1的表达评分在CRC组织与正常黏膜组织中分别为1.25±0.78和2.02±0.77,组间差异有统计学意义（P<0.001）;在高、中、低分化的CRC组织中分别为1.75±0.53,1.29±0.41,0.89±0.49,组间差异有统计学意义（P<0.05）;在不同分期的CRC组织间、良性息肉与正常黏膜间、转移淋巴结与其配对的原发癌间,差异均无统计学意义（均P>0.05）。各CRC细胞株经NaB分化诱导后,SELENBP1表达均明显增高（均P<0.05）。结论：CRC组织SELENBP1表达降低,SELENBP1表达降低与CRC低分化程度有关,但与疾病进展及淋巴结转移无关。

SeLeNBP1 expression in colorectal cancer and its relation with differentiation of the tumor

Objective: To screen out the protein showing most significant differential expression in colorectal cancer (CRC) tissues through proteomic technique, and then to analyze its relation with the disease profile. Methods: The surgical specimens from 83 CRC patients were collected, which included the CRC tissues, normal colonic mucosal tissues, metastatic lymph nodes and concomitant benign colonic polyps from some of the patients. Proteomics analysis that consisted of 2D differential gel electrophoresis (2D DIGE) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) was performed in CRC and normal colonic mucosa tissues. The protein of interest was validated by Western blot analysis in CRC and normal colonic mucosal tissues along with different CRC cell lines, after it was identified. The expression of this protein was also determined by immunohistochemical staining in the paraffin-embedded specimens of CRC tissue, normal mucosal tissue, benign polyp and lymph node metastasis. Western blot was performed to observe the changes of the protein expression in CRC cell lines after induction of differentiation by sodium butyrate (NaB). Results: The results of 2D DIGE analysis and MALDI-TOF-MS identification showed that the expression abundance of selenium binding protein 1 (SELENBP1) in CRC tissue was significantly decreased (2.54 folds) compared with mucosal tissue (P<0.01). Western blot analysis showed that the SELENBP1 expression level in CRC tissue was significantly lower than that in their paired normal mucosal tissue (0.76±0.37 vs. 1.46±0.56) (P<0.001), and SELENBP1 expression was generally decreased in CRC cell lines. Immunohistochemistry analysis showed that the expression scores of SELENBP1 protein in CRC and normal mucosal tissue were 1.25±0.78 and 2.02±0.77 respectively, with statistical significance (P<0.001); in well, moderately and poorly differentiated CRC tissues were 1.75±0.53, 1.29±0.41 and 0.89±0.49 respectively, with statistical significance (P<0.05); no statistical difference was found among different stages of CRC tissues, between benign polyp and normal mucosal tissue or between metastatic lymph node and primary tumor (all P>0.05). The SELENBP1 expressions in all the tested CRC cell lines were significantly increased following NaB induced differentiation (all P<0.05). Conclusion: SELENBP1 suppression is decreased in CRC tissue, and its decrease is associated with the degree of poor differentiation of CRC, but irrelevant to disease progression and lymph node metastasis.