title: Long non-coding RNAs with low expression levels in cells are enriched in secreted exosomes.
abstract: Long non-coding RNAs (lncRNAs) are involved in regulating chromatin modifications, gene transcription, mRNA translation, and protein function. We recently reported a high variation in the basal expression levels of a panel of lncRNAs in HeLa and MCF-7 cells and their differential response to DNA damage induction. Here, we hypothesized that lncRNA molecules with different cellular expression may have a differential abundance in secreted exosomes, and their exosome levels would reflect cellular response to DNA damage. MALAT1, HOTAIR, lincRNA-p21, GAS5, TUG1, CCND1-ncRNA in exosomes secreted from cultured cells were characterized. A different expression pattern of lncRNAs in exosomes was seen compared to cells. RNA molecules with relative low expression levels (lincRNA-p21, HOTAIR, ncRNA-CCND1) were highly enriched in exosomes. TUG1 and GAS5 levels were moderately elevated in exosomes, whereas MALAT1--which was the most abundant molecule in cells--was present at levels comparable to its cellular levels. lincRNA-p21 and ncRNA-CCND1 were the main molecules; exosome levels of them best reflect the change of their cellular levels upon exposure of the cells to bleomycin-induced DNA damage. In conclusion, we provide evidence that lncRNAs have a differential abundance in exosomes, indicating a selective loading.
authors.affiliation: Department of Basic Oncology, Oncology Institute, Istanbul University, Istanbul, Turkey.
authors.forename: Ugur
authors.initials: U
authors.lastname: Gezer
authors.forename: Emre
authors.initials: E
authors.lastname: Özgür
authors.forename: Merve
authors.initials: M
authors.lastname: Cetinkaya
authors.forename: Mustafa
authors.initials: M
authors.lastname: Isin
authors.forename: Nejat
authors.initials: N
authors.lastname: Dalay
mesh_terms: D004249:DNA Damage; D055354:Exosomes / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D062085:RNA, Long Noncoding / Q000378:metabolism*
chemical_list: D062085:RNA, Long Noncoding
keywords: HeLa cells; MCF-7 cells; exosomes; long noncoding RNAs