Nucleobindin-2 Mediates Transforming Growth Factor-β1–Driven Phenotypes in Zinc Finger E-Box Binding Homeobox 1–High Uterine Carcinosarcoma

Epithelial-mesenchymal transition (EMT) is a hallmark of uterine carcinosarcoma (UCS). Here, we used shotgun proteomics analysis to identify biomarkers associated with blebbistatin-mediated EMT in UCS, and found upregulation of nucleobindin-2 (NUCB2) in endometrial carcinoma (Em Ca) cells. Expression of N-cadherin, Snail, Slug, and ZEB1, was reduced in NUCB2 knockout Em Ca cells, whereas ZEB1, Twist1, and vimentin were upregulated in NUCB2-overexpressing Em Ca cells. NUCB2 knockout reduced cell proliferation and migration, whereas NUCB2 overexpression had the opposite effect. Treatment of Em Ca cells with TGF-β1 dramatically altered morphology toward a fibroblastic appearance; concomitantly, expression of NUCB2 and ZEB1 increased. The NUCB2 promoter was also activated by transfection of Smad2. In UCS tissues, NUCB2 expression was significantly higher in sarcomatous as compared to carcinomatous components; this was consistent with increased TGF-β1 mRNA expression in stromal and sarcomatous components as compared to carcinomatous components. In addition, NUCB2 score correlated positively with ZEB1 and vimentin scores, whereas ZEB1 score correlated positively with Slug and vimentin scores and inversely with the E-cadherin score. We therefore suggest that TGF-β-dependent upregulation of NUCB2 and ZEB1 contributes to the phenotypic characteristics of sarcomatous components in UCS.