结直肠癌原发灶及其肝转移灶的蛋白表达差异研究

目的研究结直肠癌发生及其肝转移过程中蛋白质的表达差异,以及这些差异蛋白与肝转移的关系。方法采用双向荧光差异凝胶电泳法(2-DDIGE)对比分析正常肠黏膜、结直肠癌原发灶及其肝转移灶中的蛋白质组表达差异,经质谱分析鉴定差异蛋白点。采用免疫组化方法验证差异蛋白在结直肠癌及其肝转移灶组织中的表达情况。结果结直肠癌原发灶与肝转移灶组织中蛋白质组分有明显差异。平均每张胶大约有900个蛋白点,结直肠癌原发灶与肝转移灶组织比较,差异倍数为1.5倍,差异点数目为46个。共分析了20个差异蛋白点,其中2个蛋白点在肝转移灶组织中表达下调,16个蛋白点肝在转移灶组织中表达上调。经质谱鉴定,激活蛋白因子2B、腺苷蛋氨酸变异体在肝转移灶组织中表达下调,锌指蛋白64同系物、鸟嘌呤核苷酸交换因子4、人精氨酸酶、人谷胱甘肽S-转移酶A3、肿瘤坏死因子α-诱导蛋白9等蛋白在肝转移灶中表达上调。经免疫组化方法验证人精氨酸酶表达在肝转移灶组织中高于原发灶组织。结论结直肠癌原发灶及其肝转移灶蛋白质组表达有显著差异,一些差异蛋白与结直肠癌的肝转移相关。人精氨酸酶可能是结直肠癌肝转移的生物标志物之一。

Proteomic analysis of differentially expressed proteins involved in primary focus and liver metastasis of human colorectal carcinomas

Objective To identify the specific protein markers involved in primary focus and liver metastasis of human colorectal carcinomas, and explore the relationship between such proteins and liver metastasis. Methods The samples collected from the liver metastasis of sixteen patients with colorectal cancer were examined with proteomic analysis. The highly sensitive two-dimensional differential gel electrophoresis (2-D DIGE), coupled with mass spectrometry (MS), was employed for the identification of proteins differentially expressed in primary cancer lesion and liver metastasis of colorectal cancer. The differentially expressed proteins found in 2-D DIGE were then confirmed and validated by immunohistochemistry analysis in the few cases for which the antibodies were available. Results Remarkable difference was found in the protein components between primary foci and liver metastasis tissue of human colorectal cancer. Of approximate 900 protein spots, 20 protein spots showed significant differences on expression between the primary foci and liver metastasis tissue, and among them 16 protein spots were up-regulated in liver metastasis tissue in comparison to primary foci. Compared with those in primary cancer foci, the expression increased in the liver metastasis tissues were as follows: zinc finger protein 64 homolog, guanine nucleotide exchange factor 4, arginase, human glutathione S-transferase A3, tumor necrosis factor alpha-induced protein 9, chain A structure of human glutamate dehydrogenase-apo form, toll-like receptor adaptor molecule 2 and ribonucleotide reductase M2 polypeptide. Conclusions Differential expression levels of proteins are found between the primary foci and liver metastasis tissues of colorectal cancer. Enhanced expressions of arginase zinc finger protein 64 homolog and guanine nucleotide exchange factor 4 are related with the liver metastasis of colorectal cancer. This proteomic study on colorectal cancer represents a step towards a better understanding of the mechanism of the colorectal cancer metastasis to the liver, and arginase, perhaps, could be used as a biomarker for liver metastasis of colorectal careinoma.