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CacyBP/SIP promotes the proliferation of colon cancer cells.

Authors :: Zhai H
Shi Y
Chen X
Wang J
Lu Y
Zhang F
Liu Z
Lei T
Fan D
Source :: PloS one [PLoS One] 2017 Feb 14; Vol. 12 (2), pp. e0169959. Date of Electronic Publication: 2017 Feb 14 (Print Publication: 2017).
Publication Year :: 2017
Abstract: CacyBP/SIP is a component of the ubiquitin pathway and is overexpressed in several transformed tumor tissues, including colon cancer, which is one of the most common cancers worldwide. It is unknown whether CacyBP/SIP promotes the proliferation of colon cancer cells. This study examined the expression level, subcellular localization, and binding activity of CacyBP/SIP in human colon cancer cells in the presence and absence of the hormone gastrin. We found that CacyBP/SIP was expressed in a high percentage of colon cancer cells, but not in normal colonic surface epithelium. CacyBP/SIP promoted the cell proliferation of colon cancer cells under both basal and gastrin stimulated conditions as shown by knockdown studies. Gastrin stimulation triggered the translocation of CacyBP/SIP to the nucleus, and enhanced interaction between CacyBP/SIP and SKP1, a key component of ubiquitination pathway which further mediated the proteasome-dependent degradation of p27kip1 protein. The gastrin induced reduction in p27kip1 was prevented when cells were treated with the proteasome inhibitor MG132. These results suggest that CacyBP/SIP may be promoting growth of colon cancer cells by enhancing ubiquitin-mediated degradation of p27kip1.<br />Competing Interests: The authors have declared that no competing interests exist.