PT - JOURNAL ARTICLE AU - HIROKI KONDO AU - YOHEI SHIMONO AU - JUNKO MUKOHYAMA AU - YASUTERU TANAKA AU - NAOKI SHIBUYA AU - HIRONOBU MINAMI AU - YOSHIHIRO KAKEJI AU - AKIRA SUZUKI TI - Discordance of <em>MCM7</em> mRNA and its Intronic MicroRNA Levels Under Hypoxia DP - 2017 Jul 01 TA - Anticancer Research PG - 3885--3890 VI - 37 IP - 7 4099 - http://ar.iiarjournals.org/content/37/7/3885.short 4100 - http://ar.iiarjournals.org/content/37/7/3885.full SO - Anticancer Res2017 Jul 01; 37 AB - Background: Intronic microRNAs (miRNAs) are considered to be transcribed using their host gene promoter. However, about one third of intronic miRNAs are predicted to have independent promoter elements. Materials and Methods: Human breast cancer cells were cultured under normoxia or hypoxia, and expression levels of intronic miR-106b-25 cluster miRNAs and their host gene minichromosome maintenance complex component 7 (MCM7) transcripts were analyzed by semi-quantitative polymerase chain reaction. The putative promoter element of miR-106b-25 cluster was analyzed by chromatin immunoprecipitation and luciferase assays. Results: Exposure to hypoxia reduced the expression of MCM7 mRNA and a primary transcript of miR-106b-25 cluster, but did not affect that of mature miRNAs. The putative promoter element of miR-106b-25 cluster was not bound by hypoxia-inducible factor 1-alpha (HIF1-α), and was not activated under hypoxia. Conclusion: Maintenance of miR-106b-25 cluster miRNA levels under hypoxia was not caused by the activation of an independent promoter element.