406995

MIR181A1

Although many researches have been undertaken to disclose the mechanisms of chemoresistance, the mechanisms remain unclear. The aim of this study is to elucidate the role of miR-181a-Twist1 pathway in the chemoresistance of tongue squamous cell carcinoma (TSCC). We found that cisplatin-induced chemoresistance in TSCC cell lines underwent EMT (epithelial-mesenchymal transition) and was accompanied by enhancing metastatic potential (migration and invasion in vitro), miR-181a downregulation and Twist1 upregulation. Functional analyses indicated that miR-181a reversed chemoresistance, inhibited EMT and metastatic potential in TSCC cells. Twist1 was confirmed as a direct miR-181a target gene by luciferase reporter gene assays. Twist1 knockdown by siRNA led to a reversal of the chemoresistance, inhibited EMT and metastatic potential in TSCC cells. Our study demonstrates that miR-181a-Twist1 pathway may play an important role in the development of cisplatin-chemoresistance, with EMT and an increase the metastatic potential of TSCC cells.CI - Copyright (c) 2013 Elsevier Inc. All rights reserved.

Chemoresistance is an inevitable occurrence in lung adenocarcinoma, which has been associated with decreased expression of the phosphatase and tensin homolog deleted on chromosome ten (PTEN). Therefore, it is important to identify novel molecular mechanisms to suppress chemoresistance in lung adenocarcinoma cells. Paclitaxel- and cisplatin-resistant A549 lung carcinoma cell derivatives were developed by long-term serial culture. The metastatic properties of the cells were assessed using wound-healing assays, migration assays, invasion assays, morphological examination, and western blot analysis/RT-PCR of genes associated with the epithelial-mesenchymal transition (EMT). To identify novel regulators of EMT in A549 cells, differentially expressed miRNAs in drug-resistant cells were identified by microarray analysis. The role of miR-181a was established by transfection with specific mimic and inhibitor followed by functional assays. Luciferase assays were performed to assess the ability of miR-181a to target the PTEN promoter, and regulation of PTEN expression by miR-181a was assessed by western blot analysis and RT-PCR. Paclitaxel- and cisplatin-resistant A549 cells acquired metastatic properties and EMT phenotype and had reduced PTEN expression as compared to sensitive cells. miR181a was identified as a differentially expressed miRNA in drug-resistant A549 cells, and miR-181a mimic and inhibitor were shown to affect migration, invasion, morphology and expression of EMT-associated genes. PTEN was identified as a direct target of miR-181a. Our findings demonstrate that miR-181a expression in lung adenocarcinoma is associated with EMT progression, potentially through targeting of PTEN. Regulation of miR-181a may provide a novel strategy for overcoming resistance to paclitaxel and cisplatin in lung adenocarcinoma.

BACKGROUND/AIMS: Kaiso (ZBTB33) expression is closely associated with the progression of many cancers and microRNA (miRNA) processing. MiR-181a plays critical roles in multiple cancers; however, its precise mechanisms in glioma have not been well clarified. The goal of this study was to evaluate the interaction between Kaiso and miR-181a in glioma. METHODS: Quantitative real-time PCR (qRT-PCR) was performed to detect the levels of Kaiso and miR-181a in glioma tissues and cell lines. Cell proliferation, invasion, and the epithelial-mesenchymal transition (EMT) were evaluated to analyze the biological functions of miR-181a and Kaiso in glioma cells. The mRNA and protein levels of Kaiso were measured by qRT-PCR and western blotting, respectively. Meanwhile, luciferase assays were performed to validate Kaiso as a miR-181a target in glioma cells. RESULTS: We found that the level of miR-181a was the lowest among miR-181a-d in glioma tissues and cell lines, and the low level of miR-181a was closely associated with the increased expression of Kaiso in glioma tissues. Moreover, transfection of miR-181a significantly inhibited the proliferation, invasion, and EMT of glioma cells, whereas knockdown of miR-181a had the opposite effect. Bioinformatics analysis predicted that Kaiso was a potential target gene of miR-181a, and the luciferase reporter assay demonstrated that miR-181a could directly target Kaiso. In addition, Kaiso silencing had similar effects as miR-181a overexpression in glioma cells, whereas overexpression of Kaiso in glioma cells partially reversed the inhibitory effects of the miR-181a mimic. Conclusionss: miR-181a inhibited the proliferation, invasion, and EMT of glioma cells by directly targeting and downregulating Kaiso expression.CI - (c) 2018 The Author(s). Published by S. Karger AG, Basel.