Kim Kun, Kim Min-Jeong, Kim Kyung-Hee, Ahn Sun-A, Kim Jong Heon, Cho Jae Youl, Yeo Seung-Gu
Colorectal Cancer Branch, Research Institute, National Cancer Center, Goyang, Gyeonggi 10408, Republic of Korea.
Laboratory of Cell Biology, Cancer Research Institute, Seoul National University, Seoul 03080, Republic of Korea.
Exp Ther Med. 2017 May;13(5):2493-2500. doi: 10.3892/etm.2017.4249. Epub 2017 Mar 21.
The present study aimed to investigate the expression of complement component 1, q subcomponent-binding protein (C1QBP) in colon cancer cells, and identify proteins that interact with C1QBP. Total proteins were extracted from both the tumor and normal tissues of 22 patients with colon cancer and analyzed using liquid chromatography-mass spectrometry (LC-MS) to identify proteins that were differentially-expressed in tumor tissues. C1QBP overexpression was induced in 293T cells using a pFLAG-CMV2 expression vector. Overexpressed FLAG-tagged C1QBP protein was then immunoprecipitated using anti-FLAG antibodies and C1QBP-interacting proteins were screened using LC-MS analysis of the immunoprecipitates. The C1QBP-interacting proteins were confirmed using reverse-immunoprecipitation and the differential expression of C1QBP in tissues and cell lines was confirmed using western blot analysis. LC-MS analysis revealed that C1QBP exhibited a typical tumor expression pattern. Two immune-reactive signals (33 and 14 kDa) were detected in normal and tumor tissues from 19 patients. Furthermore, 14 kDa C1QBP protein was upregulated in the tumors of 15 patients. In total, 39 proteins were identified as candidate C1QBP-interacting proteins, and an interaction between C1QBP and apolipoprotein A-I was confirmed. The present study indicates that C1QBP is involved in colon cancer carcinogenesis, and that the mechanisms underlying the established anti-tumor properties of apolipoprotein A-I may include interacting with and inhibiting the activity of C1QBP.
本研究旨在调查补体成分1q亚成分结合蛋白（C1QBP）在结肠癌细胞中的表达，并鉴定与C1QBP相互作用的蛋白质。从22例结肠癌患者的肿瘤组织和正常组织中提取总蛋白，采用液相色谱-质谱联用（LC-MS）分析，以鉴定在肿瘤组织中差异表达的蛋白质。使用pFLAG-CMV2表达载体在293T细胞中诱导C1QBP过表达。然后使用抗FLAG抗体对过表达的FLAG标记的C1QBP蛋白进行免疫沉淀，并通过对免疫沉淀物的LC-MS分析筛选与C1QBP相互作用的蛋白质。通过反向免疫沉淀法确认与C1QBP相互作用的蛋白质，并通过蛋白质印迹分析确认C1QBP在组织和细胞系中的差异表达。LC-MS分析显示C1QBP呈现典型的肿瘤表达模式。在19例患者的正常组织和肿瘤组织中检测到两个免疫反应信号（33 kDa和14 kDa）。此外，14 kDa的C1QBP蛋白在15例患者的肿瘤中上调。总共鉴定出39种蛋白质作为与C1QBP相互作用的候选蛋白质，并确认了C1QBP与载脂蛋白A-I之间的相互作用。本研究表明，C1QBP参与结肠癌的致癌过程，载脂蛋白A-I既定的抗肿瘤特性的潜在机制可能包括与C1QBP相互作用并抑制其活性。
