结直肠癌肝转移蛋白质组表达差异及其意义的研究

Proteomic study on hepatic metastasis of colorectal cancer

目的利用蛋白质组研究技术分离、鉴定结直肠癌肝转移相关蛋白,探讨结直肠癌肝转移分子机制。方法用等电聚焦/SDS聚丙烯酰胺双向凝胶电泳对比分析结直肠癌原发灶、癌旁肠黏膜和肝转移灶中蛋白质组表达差异,经MALDI-TOF-MS质谱分析、鉴定差异蛋白点,采用Western杂交检测结直肠癌肝转移相关蛋白表达。结果经双向电泳图像对比分析,癌旁肠黏膜组织中蛋白质斑点为(390±28)个,结直肠癌原发灶和肝转移灶中蛋白质斑点分别为(206±22)个和(236±19)个。结直肠癌肝转移灶中蛋白质表达与癌原发灶、癌旁肠黏膜相比差异有显著性意义(t=17.321、t=29.637,P<0.01)。对肝转移灶中一个特异蛋白质点行质谱检测,经Profound检索同源分析,确定该蛋白点相对分子质量为21.25×103,等电点为6.8,与细胞周期蛋白42(Cdc42)同源。Western杂交检测25例结直肠癌标本,癌旁肠黏膜中Cdc42表达检测为阴性。在癌原发灶中Cdc42表达阳性率为16%(4/25)。肝转移灶中检测Cdc42表达阳性率为100%(25/25)。结论结直肠癌肝转移蛋白质组表达差异研究有助于鉴定在肝转移中起重要作用的蛋白质,Cdc42作为结直肠癌肝转移相关蛋白,对癌细胞生物学行为改变有重要影响,可促进肝转移的发生。

Objective To identify proteins correlated to hepatic metastasis of colorectal cancer and to study its molecular mechanism. Methods Isoelectric focusing/SDS acrylamine gel was used to separate and analyze differential expression proteins among primary foci, paratumor mucosa and hepatic metastases of colorectal cancer. Mass spectrum analysis of the differential expression protein spots were performed with MALDI-TOF-MS. Western blot was used to detect the expression of hepatic metastasis associated proteins. Results With two-dimensional electrophoresis, 390±28 spots of proteins were found in paratumor mucosa, and the spot numbers in primary foci and hepatic metastasis were 206±22 and 236±19 respectively. The differences were significant in protein spot numbers among the primary foci, paratumor mucosa and hepatic metastases (t=17.321,29.637,P< 0.01). A specific protein spot in hepatic metastases was detected with mass spectrum. Peptide dactylogram analysis was carried out with Profound software. The molecular weight of CH1 was 21.25×103,and the isoeletric point was 6.8. It was homologic with cell division cycle 42(Cdc 42). Cdc 42 expression was detected with Western blot in 25 cases of colorectal cancer. In paratumor mucosa, Cdc 42 expression was negative. But in the primary foci and hepatic metastasis, Cdc 42 expression rate was 16%(4/25)and 100%(25/25)respectively. Conclusions Proteomic study on hepatic metastases of colorectal cancer helps to identify the specific proteins that play important roles in hepatic metastasis. Cdc 42 is a protein correlated with hepatic metastasis, which may cause biological behavior changes of the cancer cells and promote hepatic metastasis.