title: Stabilization of ribozyme-like cis-noncoding rRNAs induces apoptotic and nonapoptotic death in lung cells.
abstract: Bidirectional non-protein-coding RNAs are ubiquitously transcribed from the genome. Convergent sense and antisense transcripts may regulate each other. Here, we examined the convergent cis-noncoding rRNAs (nc-rRNAs) in A5 and E9 lung cancer models. Sense nc-rRNAs extending from rDNA intergenic region to internal transcribed spacer of around 10 kb in length were identified. nc-rRNAs in sense direction exhibited in vitro characteristics of ribozymes, namely, degradation upon incubation with MgCl(2) and stabilization by complementary oligonucleotides. Detection of endogenous cleavage-ligation products carrying internal deletion of hundreds to thousands nucleotides by massively parallel sequencing confirmed the catalytic properties. Transfection of oligonucleotides pairing with antisense nc-rRNAs stabilized both target and complementary transcripts, perturbed rRNA biogenesis, and induced massive cell death via apoptotic and/or nonapoptotic mechanisms depending on cell type and treatment. Oligonucleotides targeting cellular sense transcripts are less responsive. Spontaneously detached cells, though rare, also showed accumulation of nc-rRNAs and perturbation of rRNA biogenesis. Direct participation of nc-rRNAs in apoptotic and nonapoptotic death was demonstrated by transfection of synthetic nc-rRNAs encompassing the rDNA promoter. In sum, convergent cis-nc-rRNAs follow a feed-forward mechanism to regulate each other and rRNA biogenesis. This opens an opportunity to disrupt rRNA biogenesis, commonly upregulated in cancers, via inhibition of ribozyme-like activities in nc-rRNAs.
authors.affiliation: Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, MD 21702, USA.
authors.forename: M
authors.initials: M
authors.lastname: Gee
authors.forename: Y
authors.initials: Y
authors.lastname: Gu
authors.forename: J R
authors.initials: JR
authors.lastname: Fields
authors.forename: Y-H
authors.initials: YH
authors.lastname: Shiao
mesh_terms: D000230:Adenocarcinoma; D000077192:Adenocarcinoma of Lung; D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D002453:Cell Cycle / Q000235:genetics; D016923:Cell Death / Q000235:genetics; D045744:Cell Line, Tumor; D004275:DNA, Ribosomal / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D059014:High-Throughput Nucleotide Sequencing; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D008175:Lung Neoplasms; D015636:Magnesium Chloride / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016337:RNA, Catalytic / Q000235:genetics / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D004275:DNA, Ribosomal; D016376:Oligonucleotides, Antisense; D016337:RNA, Catalytic; D012335:RNA, Ribosomal; D022661:RNA, Untranslated; D015636:Magnesium Chloride