title: The mechanism involved in the loss of PTEN expression in NSCLC tumor cells.
abstract: Loss of PTEN expression is observed in most non-small cell lung cancers (NSCLC). However, the mechanism by which PTEN expression is regulated in NSCLC has not been fully elucidated. In this study, we investigated the role of DNA methyltransferases (Dnmts), microRNA-29b (miR-29b), and anti-miR-29b inhibitor in PTEN promoter methylation and PTEN gene expression in H358 NSCLC cells in vitro and in vivo. PTEN mRNA was measured by RT-PCR. PTEN and Dnmts protein levels were measured by Western blot. miR-29b expression was detected by Northern blot. A xenograft H358 tumor mouse model was established by subcutaneously inoculating H358 cells into the right hind limbs of nude mice. We found that radiation induced cell apoptosis and hypomethylation in PTEN promoter, PTEN and miR-29b expression, and downregulation of Dnmt1, 3a and 3b expression in H358 tumor cells. The effect of radiation on gene expression and apoptosis was blocked by anti-miR-29b inhibitor. In the xenograft H358 tumor model, anti-miR-29b inhibitor reversed radiation-induced tumor growth delay, PTEN reexpression and downregulation of Dnmts expression. Our study suggested that miR-29b is an upstream molecule of PTEN. miR-29b regulates PTEN gene expression through downregulating Dnmts expression and subsequently induces hypomethylation in PTEN promoter. Targeting therapy could be established in NSCLC by upregulating miR-29b expression.
authors.affiliation: Department of Radiology, Xiangya Hospital, Central South University, Changsha 410008, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Jingfeng
authors.initials: J
authors.lastname: Zhao
authors.forename: Xianjing
authors.initials: X
authors.lastname: Peng
authors.forename: Jian
authors.initials: J
authors.lastname: Liang
authors.forename: Xin
authors.initials: X
authors.lastname: Deng
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Chen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D019175:DNA Methylation; D000090205:DNA Methyltransferase 3A; D015536:Down-Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000528:radiation effects; D014176:Protein Biosynthesis; D025521:Tumor Suppressor Proteins / Q000235:genetics*; D015854:Up-Regulation; D023041:Xenograft Model Antitumor Assays
chemical_list: C000717967:DNMT3A protein, human; C532045:MIRN29a microRNA, human; D035683:MicroRNAs; D025521:Tumor Suppressor Proteins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human