title: Identification and experimental validation of G protein alpha inhibiting activity polypeptide 2 (GNAI2) as a microRNA-138 target in tongue squamous cell carcinoma.
abstract: MicroRNA deregulation is a critical event in tumor initiation and progression. The down-regulation of microRNA-138 has been frequently observed in various cancers, including tongue squamous cell carcinoma (TSCC). Our previous studies suggest that deregulation of miR-138 is associated with the enhanced proliferation and invasion in TSCC cells. Here, we seek to identify the targets of miR-138 in TSCC, and explore their functional relevance in tumorigenesis. Our genome-wide expression profiling experiments identified a panel of 194 unique transcripts that were significantly down-regulated in TSCC cells transfected with miR-138. A comprehensive screening using six different sequence-based microRNA target prediction algorithms revealed that 51 out of these 194 down-regulated transcripts are potential direct targets for miR-138. These targets include: chloride channel, nucleotide-sensitive, 1A (CLNS1A), G protein alpha inhibiting activity polypeptide 2 (GNAI2), solute carrier family 20, member 1 (SLC20A1), eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1), and Rho-related GTP-binding protein C (RhoC). GNAI2 is a known proto-oncogene that is involved in the initiation and progression of several different types of tumors. Direct targeting of miR-138 to two candidate binding sequences located in the 3'-untranslated region of GNAI2 mRNA was confirmed using luciferase reporter gene assays. Knockdown of miR-138 in TSCC cells enhanced the expression of GNAI2 at both mRNA and protein levels. In contrast, ectopic transfection of miR-138 reduced the expression of GNAI2, which, in consequence, led to reduced proliferation, cell cycle arrest and apoptosis. In summary, we identified a number of high-confident miR-138 target genes, including proto-oncogene GNAI2, which may play an important role in TSCC initiation and progression.
authors.affiliation: Center for Molecular Biology of Oral Diseases, College of Dentistry, University of Illinois at Chicago, 801 S. Paulina Street, Room 530C, Chicago, IL 60612, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Jiang
authors.forename: Yang
authors.initials: Y
authors.lastname: Dai
authors.forename: Xiqiang
authors.initials: X
authors.lastname: Liu
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.forename: Anxun
authors.initials: A
authors.lastname: Wang
authors.forename: Zujian
authors.initials: Z
authors.lastname: Chen
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Heidbreder
authors.forename: Antonia
authors.initials: A
authors.lastname: Kolokythas
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Zhou
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D005260:Female; D051960:GTP-Binding Protein alpha Subunit, Gi2 / Q000235:genetics*; D016147:Genes, Tumor Suppressor; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D000090063:Proto-Oncogene Mas; D014062:Tongue Neoplasms / Q000235:genetics*
chemical_list: C000715470:MAS1 protein, human; C546110:MIRN138 microRNA, human; D035683:MicroRNAs; D000090063:Proto-Oncogene Mas; C498015:GNAI2 protein, human; D051960:GTP-Binding Protein alpha Subunit, Gi2