Proteasome inhibitor-resistant cells cause EMT-induction via suppression of E-cadherin by miR-200 and ZEB1

• Published in: International journal of oncology Vol. 46; no. 5; pp. 2251 - 2260
• Main Authors: ASAKURA, TADASHI, YAMAGUCHI, NORIKO, OHKAWA, KIYOSHI, YOSHIDA, KIYOTSUGU
• Format: Journal Article
• Language: English
• Published: Greece D.A. Spandidos 01.05.2015; Spandidos Publications; Spandidos Publications UK Ltd
• Subjects: Apoptosis; Blotting, Western; Cadherins; Cadherins - biosynthesis; Cancer therapies; Cell adhesion & migration; Cell Line, Tumor; drug resistance; Drug Resistance, Neoplasm - genetics; E-cadherin; Endometrial cancer; Endometrial Neoplasms - genetics; Enzymes; epithelial-mesenchymal transition; Epithelial-Mesenchymal Transition - genetics; Female; Gene expression; Gene Expression Regulation, Neoplastic - genetics; Genetic aspects; Genotype & phenotype; Homeodomain Proteins - genetics; Humans; Metastasis; MicroRNAs - genetics; miR-200; Physiological aspects; proteasome inhibitor; Proteasome Inhibitors - pharmacology; Reverse Transcriptase Polymerase Chain Reaction; Transcription Factors - genetics; ZEB1; Zinc Finger E-box-Binding Homeobox 1; Japan
• ISSN: 1019-6439; 1791-2423
• DOI: 10.3892/ijo.2015.2916

Downregulation of E-cadherin (gene: CDH1) plays an important role in epithelial-mesenchymal transition (EMT), which is critical for normal development and disease states. As a result of long-term treatment of endometrial carcinoma Ishikawa cells with epoxomicin (EXM), the cells exhibited the phenotype for EXM-resistance (Ish/EXM cells). Moreover, CDH1 mRNA and its protein were suppressed and EMT was induced in Ish/EXM cells. Ish/EXM cells exhibited drug-resistance to other proteasome inhibitors, MG-132, PSI and PS-341 (Bortezomib). The proteasome inhibitor-resistant cells acquired invasiveness as a result of the chemotherapy. In Ish/EXM cells, E-cadherin was suppressed by upregulation of its transcriptional repressor ZEB1. Furthermore, expression of the miR-200 family (miR-200a, miR-200b, miR-200c and miR-141) found in Ishikawa cells was suppressed in Ish/EXM cells. Overexpression of the miR-200 family in Ish/EXM cells caused by transfection with the pre-miR-200 family induced downregulation of ZEB1 and enhanced expression of E-cadherin. Conversely, suppression of miR-200 expression in the Ishikawa cells by transfection with anti-miR-200 elevated the expression of ZEB1 and suppressed the expression of E-cadherin. These results suggest that acquirement of EXM-resistance in Ish/EXM cells induces up regulation of ZEB1 via suppression of the miR-200 family following suppression of E-cadherin. Since suppression of ZEB1 in Ish/EXM cells by treatment with its siRNA did not restore the miR-200 family expression, miR-200 family was placed upstream of ZEB1 to regulate the expression.