CacyBP/SIP Protein Is Important for the Proliferation of Human Glioma Cells

Recently, calcyclin-binding protein or Siah-1-interacting protein (CacyBP/SIP), a component of a novel ubiquitinylation pathway, could regulate the -catenin degradation (Fukushima et al., Immunity 2006, 24, 29 - 39). However, the potential role of CacyBP/SIP itself in human glioma cells has not been clarified. Here, we found that CacyBP/SIP was expressed highly in human glioma tissues. Silencing of CacyBP/SIP by short-hairpin RNA severely suppressed the proliferation of human glioma cell U251, which was at least partly mediated by downregulation of phospho-Akt (p-Akt) and phospho--catenin (p--catenin) as well as upregulation of p53 and p21. Furthermore, overexpression of CacyBP/SIP obviously promoted the proliferation of human glioma U251, which exhibited the exactly contrary trend in the expression of p-Akt, p--catenin, p53, and p21. Taken together, these findings suggest that CacyBP/SIP plays important roles in the proliferation of human glioma cell which might be involved in the development of human glioma. (c) 2014 IUBMB Life, 66(4):286-291, 2014