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Exp Ther Med. 2017 May;13(5):2493-2500. doi: 10.3892/etm.2017.4249. Epub 2017 Mar 21.

C1QBP is upregulated in colon cancer and binds to apolipoprotein A-I.

Author information

1
Colorectal Cancer Branch, Research Institute, National Cancer Center, Goyang, Gyeonggi 10408, Republic of Korea.
2
Laboratory of Cell Biology, Cancer Research Institute, Seoul National University, Seoul 03080, Republic of Korea.
3
Department of Radiology, Hallym Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Gyeonggi 14068, Republic of Korea.
4
Cancer Cell and Molecular Biology Branch, Research Institute, National Cancer Center, Goyang, Gyeonggi 10408, Republic of Korea.
5
Department of Genetic Engineering, Sungkyunkwan University, Suwon, Gyeonggi 16419, Republic of Korea.
6
Department of Radiation Oncology, Soonchunhyang University College of Medicine, Soonchunhyang University Hospital, Cheonan, South Chungcheong 31151, Republic of Korea.

Abstract

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.

KEYWORDS:

apolipoprotein A-I; colon cancer; complement component 1; proteomics; q subcomponent-binding protein

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