RESUMO
BACKGROUND/AIM: MicroRNAs (miRNAs) are closely associated with a number of cellular processes, including cell development, differentiation, proliferation, carcinogenesis, and apoptosis. The aim of the present study was to elucidate the molecular mechanisms underlying the tumor suppressor activity of miRNA-203 (miR-203) in YD-38 human oral cancer cells. MATERIALS AND METHODS: Polymerase chain reaction analysis, MTT assay, DNA fragmentation assay, fluorescence-activated cell-sorting analysis, gene array, immunoblotting, and luciferase assay were carried out in YD-38 cells. RESULTS: miR-203 expression was significantly down-regulated in YD-38 cells compared to expression levels in normal human oral keratinocytes. miR-203 decreased the viability of YD-38 cells in a time- and dose-dependent manner. In addition, over-expression of miR-203 significantly increased not only DNA segmentation, but also the apoptotic population of YD-38 cells. These results indicate that miR-203 overexpression induces apoptosis in YD-38 cells. Target gene array analysis revealed that the expression of the polycomb complex protein gene Bmi-1, a representative oncogene, was significantly down-regulated by miR-203 in YD-38 cells. Moreover, both mRNA and protein levels of Bmi-1 were significantly reduced in YD-38 cells transfected with miR-203. These results indicate that Bmi-1 is a target gene of miR-203. A luciferase reporter assay confirmed that miR-203 suppressed Bmi-1 expression by directly targeting the 3'-untranslated region. CONCLUSION: miR-203 induces apoptosis in YD-38 cells by directly targeting Bmi-1, which suggests its possible application as an anti-cancer therapeutic.
Assuntos
Apoptose/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Complexo Repressor Polycomb 1/genética , Regiões 3' não Traduzidas/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Sobrevivência Celular/genética , Regulação para Baixo , Humanos , Neoplasias Bucais/genética , Neoplasias Bucais/metabolismo , Neoplasias Bucais/patologia , Complexo Repressor Polycomb 1/metabolismoRESUMO
BACKGROUND/AIM: The purpose of this study was to elucidate the molecular mechanism underlying regulation of semaphorin-6A (SEMA6A) involving microRNA-203 (miR-203) as a tumor suppressor in YD-38 human oral cancer cells. MATERIALS AND METHODS: miRNA arrays, polymerase chain reaction analyses, MTT assays, immunoblotting, and luciferase assays were carried out in YD-38 cells. RESULTS: MiRNA microarray results showed that expression of miR-203 was significantly down-regulated in YD-38 cells compared to normal human oral keratinocytes. The viability of YD-38 cells was reduced by miR-203 in time- and dose-dependent manners. Overexpression of miR-203 increased the nuclear condensation of YD-38 cells and activated the apoptotic signaling pathway by up-regulating pro-apoptotic factors, such as BCL-2-associated X protein (BAX) and BCL-2 homologous antagonist killer (BAK), and the active forms of caspase-9, caspase-3, and poly-(ADP-ribose)-polymerase (PARP). Furthermore, target gene array analyses revealed that the expression of class 6 semaphorin A (SEMA6A) was down-regulated by miR-203 in YD-38 cells. Both the mRNA and protein levels of SEMA6A were reduced in YD-38 cells transfected with miR-203. Luciferase activity assay confirmed that miR-203 directly targets the SEMA6A 3'-untranslated region to suppress gene expression. CONCLUSION: Our results indicate that miR-203 induces the apoptosis of YD-38 human oral cancer cells by directly targeting SEMA6A, suggesting its potential application in anticancer therapeutics.
