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Anticancer Res. 2017 Jul;37(7):3885-3890.

Discordance of MCM7 mRNA and its Intronic MicroRNA Levels Under Hypoxia.

Author information

1
Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Japan.
2
Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Japan yshimono@med.kobe-u.ac.jp.
3
Division of Medical Oncology/Hematology, Kobe University Graduate School of Medicine, Kobe, Japan.
4
Division of Gastrointestinal Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.

Abstract

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.

KEYWORDS:

HIF1-α; MCM7; hypoxia; intronic microRNA; miR-106b-25 cluster

PMID:
28668890
DOI:
10.21873/anticanres.11769
[Indexed for MEDLINE]

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