MicroRNA-200a Targets EGFR and c-Met to Inhibit Migration, Invasion, and Gefitinib Resistance in Non-Small Cell Lung Cancer

Implications of MicroRNAs in the Treatment of Gefitinib-Resistant Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) represents about 85% of the reported cases of lung cancer. Acquired resistance to targeted therapy with epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), such as gefitinib, is not uncommon. It is thus vital to explore novel strategies to restore sensitivity to gefitinib. Provided that microRNAs (miRNAs) negatively regulate their gene targets at the transcriptional level, it is speculated that miRNA mimetics may reduce the expression, activity and signal transduction of EGFR so that sensitization of tumour sites to gefitinib-induced cytotoxicity can be achieved. Indeed, a growing body of evidence has shown that the manipulation of endogenous levels of miRNA not only attenuates the EGFR/PI3K/Akt phosphorylation cascade, but also restores apoptotic cell death in in vitro models of experimentally-induced gefitinib resistance and provoked tumour regression/shrinkage in xenograft models. These data are in concordant with the clinical data showing that the differential expression profiles of miRNA in tumour tissues and blood associate strongly with drug response and overall survival. Furthermore, another line of studies indicate that the chemopreventive effects of a variety of natural compounds may involve miRNAs. The present review aims to discuss the therapeutic capacity of miRNAs in relation to recent discoveries on EGFR-TKI resistance, including chronic drug exposure and mutations.

RETRACTED: MicroRNA-138 modulates metastasis and EMT in breast cancer cells by targeting vimentin

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concerns were raised in the public domain and also reported by the authors to the journal regarding the similarity between panels from Figures 3A and 4C. In addition to the institutional investigation, the journal requested the authors to provide the raw data. However, the authors have not fulfilled this request, and therefore the Editor-in-Chief decided to retract the article.

MicroRNA-200a mediates nasopharyngeal carcinoma cell proliferation through the activation of nuclear factor-κB

In nasopharyngeal carcinoma (NPC), the nuclear factor-κB (NF-κB) signaling pathway is highly active. The constitutive activation of NF-κB prompts malignant cell proliferation, and microRNAs are considered an important mediator in regulating the NF-κB signaling pathway. The current study investigated the effect of microRNA-200a (miR-200a) on NF-κB activation. Reverse transcription-quantitative polymerase chain reaction was used to quantify the relative level of miR-200a in NPC tissue samples and CNE2 cells. An MTT assay was used to investigate the effect of miR-200a on cell proliferation. To investigate the activation of NF-κB, western blotting was used to measure the protein levels of NF-κB and its downstream targets. To identify the target genes of miR-200a, a luciferase reporter assay was used. The current study demonstrated that miR-200a was upregulated in NPC tissue samples and cell lines. Overexpression of miR-200a resulted in the proliferation of CNE2 cells. Western blot analysis indicated that the protein levels of p65 increased when CNE2 cells were transfected with miR-200a mimics. Additionally, the downstream targets of miR-200a were upregulated, including vascular cell adhesion molecule, intercellular adhesion molecule and monocyte chemoattractant protein-1. The luciferase assay indicated that IκBα was the target gene of miR-200a. In conclusion, miR-200a was demonstrated to enhance NPC cell proliferation by activating the NF-κB signaling pathway.