Fucosyltransferase-1 as a Downstream Effector of Calreticulin in Regulating the metastatic Behavior of Bladder Cancer Cells
Date Issued
2014
Date
2014
Author(s)
Lu, Yi-Chien
Abstract
Bladder cancer is a common urothelial cancer. Through proteomic approaches, calreticulin (CRT) was identified and proposed as a urinary marker for bladder cancer. CRT is a multifunctional molecular chaperone that regulates various cellular functions such as Ca2+ homeostasis and cell adhesion. CRT was reported to be overexpressed in various cancers; however, the mechanisms of CRT in bladder tumor development remain unclear. To clarify the roles of CRT in bladder cancer, J82 bladder cancer cells stably overexpressed or knockdown of CRT were generated to investigate the physiological effects of CRT on bladder tumors. Compared to the transfected control vector cells, the knockdown of CRT suppressed cell proliferation, migration, and attachment; on the contrary, overexpression of CRT enhanced cell migration and attachment. Most importantly, we observed that tumors derived from J82 CRT-RNAi cells were significantly smaller and had fewer metastatic sites in the lung and liver in vivo than did transfected control vector cells. To further investigate the precise mechanism of tumor metastasis regulated by CRT, we used DNA array to identify fucosyltransferase-1 (FUT1) as a gene regulated by CRT expression levels. CRT regulated cell adhesion through α1,2-linked fucosylation on β1-integrin and this modification was catalyzed by FUT1. To clarify FUT1 roles in bladder cancer, we transfected the human FUT1 gene into CRT-RNAi stable cell lines. FUT1 overexpression in CRT-RNAi cells resulted in increased levels of β1-integrin fucosylation and rescued cell adhesion to type-I collagen. Treatment with Ulex europaeus agglutinin I (UEA-1), a lectin recognizes FUT1-modified glycosylation structures, did not affect cell adhesion. In contrast, a FUT1-specific fucosidase diminished the activation of β1-integrin. These results indicated that α1,2-fucosylation on β1-integrin were not involved in the integrin-collagen interaction but promoted β1-integrin activation. In addition, we demonstrated that CRT regulated FUT1 mRNA degradation in 3′-untranslated region (3′-UTR). In conclusion, our findings suggested that CRT stabilized FUT1 mRNA, thereby leading to increase in fucosylation of β1-integrin. Furthermore, increased fucosylation levels activate β1-integrin rather than directly modifying the integrin binding sites.
Subjects
膀胱癌
細胞貼附
癌症轉移
鈣網蛋白
岩藻糖轉移酵素
整合蛋白活性
SDGs
Type
thesis
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