ZEB1 transcriptionally regulated carbonic anhydrase 9 mediates the chemoresistance of tongue cancer via maintaining intracellular pH

作者：Guopei Zheng, Cong Peng, Xiaoting Jia, Yixue Gu, Zhijie Zhang, Yingen Deng, Chengkun Wang, Nan Li, Jiang Yin, Xiaorong Liu, Minying Lu, Hailin Tang, Zhimin He · 发表于：Molecular Cancer · 年份：2015 · DOI：10.1186/s12943-015-0357-6 · 被引用次数：47 · 研究领域：Enzyme function and inhibition、Ion Transport and Channel Regulation、Glutathione Transferases and Polymorphisms

BACKGROUND: Chemoresistance is a major obstacle in successfully treating cancers, and the mechanisms responsible for drug resistance are still far from understood. Carbonic anhydrase 9 (CA9) has been shown to be upregulated in the drug-resistant tongue cancer cell line Tca8113/PYM and to be associated with drug resistance. However, the mechanisms regulating CA9 expression and its role in drug resistance remain unclear. METHODS: Bioinformatic and experimental analysis involving ChIP and luciferase reporter assays were used to validate Zinc finger E-box-binding homeobox 1 (ZEB1) as a transcriptional regulator of CA9. Gene expression and protein levels were evaluated by quantitative RT-PCR and western blotting, respectively. Sensitivity to chemotherapy was examined using the MTS assay and Hoechst staining and analysis caspase-3 activity to evaluate changes in apoptosis. Intracellular pH (pHi) was measured using fluorescent pH-indicator BCECF-AM. Protein expression in patient tissue samples was examined by immunohistochemistry and survival of tongue cancer patients from which these samples were derived was also analyzed. RESULTS: ZEB1 bound to the promoter of CA9 to positively regulate CA9 expression in tongue cancer cells. Knockdown of CA9 using short interfering RNA (siRNA) abolished the chemoresistance resulting from ZEB1 overexpression in Tca8113 and SCC-25 cells, and CA9 overexpression attenuated chemosensitivity induced by ZEB1 knockdown in Tca8113/PYM cells. CA9 knockdown ...