TGF-β1/Smad Signaling Pathway Regulates Epithelial-to-Mesenchymal Transition in Esophageal Squamous Cell Carcinoma: In Vitro and Clinical Analyses of Cell Lines and Nomadic Kazakh Patients from Northwest Xinjiang, China

Abstract

Invasion and metastasis are the major causes of death in patients with esophageal squamous cell carcinoma (ESCC). Epithelial-mesenchymal transition (EMT) is a critical step in tumor progression and transforming growth factor-β1 (TGF-β1) signaling has been shown to play an important role in EMT. In this study, we investigated how TGF-β1 signaling pathways contributed to EMT in three ESCC cell lines as well as 100 patients of nomadic ethnic Kazakhs residing in northwest Xinjiang Province of China. In vitro analyses included Western blotting to detect the expression of TGF-β1/Smad and EMT-associated proteins in Eca109, EC9706 and KYSE150 cell lines following stimulation with recombinant TGF-β1 and SB431542, a potent inhibitor of ALK5 that also inhibits TGF-β type II receptor. TGF-β-activated Smad2/3 signaling in EMT was significantly upregulated as indicated by mesenchymal markers of N-cadherin and Vimentin, and in the meantime, epithelial marker, E-cadherin, was markedly downregulated. In contrast, SB431542 addition downregulated the expression of N-cadherin and Vimentin, but upregulated the expression of E-cadherin. Moreover, the TGF-β1-induced EMT promoted invasion capability of Eca109 cells. Tumor cells undergoing EMT acquire fibroblastoid-like phenotype. Expressed levels of TGF-β1/Smad signaling molecules and EMT-associated proteins were examined using immunohistochemical analyses in 100 ESCC tissues of Kazakh patients and 58 matched noncancerous adjacent tissues. The results showed that ESCC tissues exhibited upregulated expression of TGF-β1/Smad. We also analyzed the relationship between the above proteins and the patients' clinicopathological characteristics. The TGF-β1/Smad signaling pathway in human Eca109 ESCC cells may carry similar features as in Kazakh ESCC patients, suggesting that TGF-β1/Smad signaling pathway may be involved in the regulation of EMT in ethnic Kazakh patients with ESCC from Xinjiang, China.

Role of matrix metalloproteinase-9 in transforming growth factor-β1-induced epithelial–mesenchymal transition in esophageal squamous cell carcinoma

“…Here, we demonstrated that TGF-β1 induces changes in the morphology of ESCC cells and their transition from epithelial to mesenchymal phenotype. This change was shown to be accompanied by the downregulation of E-cadherin and upregulation of vimentin expression, which is consistent with the data obtained in the previous studies 12,13…”

Effects of Astragaloside IV Against the TGF-β1-Induced Epithelial-to-Mesenchymal Transition in Peritoneal Mesothelial Cells by Promoting Smad 7 Expression

“…phosphorylated Smad2/3 and Smad4 translocate to the nucleus, where they cooperate with transcription factors such as Snail and Twist to repress the expression of epithelial markers and activate the expression of mesenchymal markers. This signaling is referred to as TGF-β-activated Smad signaling in EMT [27][28][29]. Similar to previous studies, 2 ng/ml of TGF-β1 decreased expression of epithelial markers, increased expression of mesenchymal markers, which was accompanied by an increase in Smad2/3 activation (increased expression of phospho-Smad2/3) in HMrSV5 cells.…”

Aberrant methylation of EYA4 promotes epithelial‐mesenchymal transition in esophageal squamous cell carcinoma

“…Distant metastasis is one of the main reasons for treatment failure in ESCC. EMT is a critical event in the progression toward cancer metastasis and many signaling pathways are involved in the regulation of EMT in ESCC, such as Akt/GSK‐3β/Snail, MAPK/ERK and TGF‐β1/Smad . Several studies have reported that the AKT/GSK‐3β signaling pathway is involved in the progression of EMT in human malignancies, such as gastric cancer, hepatocellular carcinoma and prostate cancer .…”

“…EMT is a critical event in the progression toward cancer metastasis and many signaling pathways are involved in the regulation of EMT in ESCC, such as Akt/GSK-3b/Snail, MAPK/ERK and TGF-b1/Smad. [25][26][27][28] Several studies have reported that the AKT/ Western blots comparing EYA4-knockdown and EYA4-overexpression cells with their respective control cells are seen in relative expression of (C) Akt, p-Akt-S473, GSK-3b, p-GSK-3b. b-actin was used as a loading control.…”