TBRG4 silencing promotes progression of squamous cell carcinoma via regulation of CAV-1 expression and ROS formation


Junqi Wang, Qing Luo, Mingwei Liu, Chao Zhang, Yong Jia, Ruifeng Tong, Litao Yang, Xiaowei Fu

Abstract


Esophageal cancer is the eighth most common cancer globally. Transforming growth factor β regulator 4 (TBRG4) and caveolin-1 (CAV-1) are implicated in tumor progression. The aim of this study was to investigate the expressions of TBRG4 and CAV-1 in esophageal squamous cell carcinoma (ESCC), and their relationship with reactive oxygen species (ROS) formation. Human ESCC cell lines (EC9706, TE-1, and Eca109), and normal esophageal mucosal cell line (Het-1) were used in this study. The silencing of TBRG4 and/or CAV-1 by sh-RNA or overexpression of CAV-1 after TBRG4 knockdown was used to assess ROS levels. The results showed that down-regulation of TBRG4 reduced CAV-1 expression, and promoted ROS formation in ESCCs (p < 0.01). However, CAV-1 overexpression increased the expression level of TBRG4, but decreased ROS level in EC9706 cells (p < 0.01). Similarly, TBRG4 knockdown significantly reduced CAV-1 expression, promoted ROS formation, and caused cell cycle arrest at G0/G1 phase (p < 0.01). Caveolin-1 (CAV-1) knockdown also promoted cell apoptosis, cellular ROS formation and cell cycle arrest at G0/G1 phase (p < 0.01). However, CAV-1 overexpression in sh-TBRG4-treated EC9706 cells significantly upregulated TBRG4 expression, but significantly reduced the level of ROS, and inhibited cell-cycle arrest and apoptosis (p < 0.01). The enhancements in bcl-2/bax ratio, cytochrome c expression, and ROS levels by sh-TBRG4 were significantly reversed by CAV-1 overexpression in EC9706 cells. These results show that the upregulated expression of TBRG4 or CAV-1 promotes ESCC progression via regulation of intracellular ROS levels and inhibition of mitochondria-dependent apoptotic pathway.

Keywords


Esophageal cancer; Caveolin-1; Reactive oxygen species; Cell apoptosis; Expression.

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