title: miR-7 inhibits the invasion and metastasis of gastric cancer cells by suppressing epidermal growth factor receptor expression.
abstract: The present study profiled differentially expressed microRNAs (miRs) in gastric cancer cell lines and then investigated miR-7 expression in gastric cancer tissue specimens and the effects of miR-7 on the growth, invasion and metastasis of gastric cancer cells and the underlying molecular events. A microRNA microarray was used to profile differentially expressed miRNAs in human gastric cancer cell lines relative to a normal stomach mucosal epithelial cell line. The miRNA miR-7 was selected for further investigation, which included real-time reverse-transcription PCR (qRT-PCR) analysis of miR-7 levels in different gastric cancer cell lines and tissues and distant non-tumor tissues from patient resections. Cell counting kit-8 (CCK-8), Transwell migration and invasion, and western blot assays were performed to assess tumor cell viability, invasion and gene expression, respectively, after miR-7 transfection. The miRNA microarray profiling revealed 14 upregulated miRNAs (including miR-21, miR-26b and miR-30b) and 19 downregulated miRNAs (including let-7i, miR-7 and miR-622) between gastric cancer and normal cell lines. The qRT-PCR analysis confirmed that reduced miR-7 expression occurred more frequently in poorly and moderately differentiated gastric cancer MGC-803, MKN-45 and SGC-7901 cell lines than in the well-differentiated gastric cancer NCI-N87 cell line, which was consistent with the results for gastric cancer tissues. Expression of miR-7 was downregulated in 86.9% (20/23) of the gastric cancer tissues compared with that in the distant non-tumor tissues. Restoration of miR-7 expression significantly inhibited tumor cell viability, invasiveness and migration when compared with the control cells. Luciferase assay confirmed the epidermal growth factor receptor (EGFR) as a target gene of mR-7, and expression of miR-7 significantly suppressed EGFR expression at both the mRNA and protein levels. The data from the present study demonstrated that reduced miR-7 expression contributes to gastric cancer development and progression. Further study will investigate miR-7 in the regulation of EGFR expression in vitro and in vivo.
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Juan
authors.initials: J
authors.lastname: Xie
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Diagnostics, Medical College of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Ming-Shu
authors.initials: MS
authors.lastname: Mo
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Li-Hui
authors.initials: LH
authors.lastname: Zhu
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Liu
authors.affiliation: Department of Diagnostics, Medical College of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Qing-Jun
authors.initials: QJ
authors.lastname: Gui
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital of the University of South China, Hengyang, Hunan 421001, P.R. China.
authors.forename: Guo-Qing
authors.initials: GQ
authors.lastname: Li
mesh_terms: D015153:Blotting, Western; D002470:Cell Survival; D066246:ErbB Receptors / Q000096:biosynthesis*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D020411:Oligonucleotide Array Sequence Analysis; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014162:Transfection
chemical_list: D066246:ErbB Receptors; D035683:MicroRNAs; C549242:MIRN7-1 microRNA, human; C512478:EGFR protein, human