title: Telomere Transcripts Target Telomerase in Human Cancer Cells.
abstract: Long non-coding transcripts from telomeres, called telomeric repeat-containing RNA (TERRA), were identified as blocking telomerase activity (TA), a telomere maintenance mechanism (TMM), in tumors. We expressed recombinant TERRA transcripts in tumor cell lines with TA and with alternative lengthening of telomeres (ALT) to study effects on TMM and cell growth. Adeno- and lentivirus constructs (AV and LV) were established for transient and stable expression of approximately 130 units of telomere hexanucleotide repeats under control of cytomegalovirus (CMV) and human RNase P RNA H1 (hH1) promoters with and without polyadenylation, respectively. Six human tumor cell lines either using telomerase or ALT were infected and analyzed for TA levels. Pre-infection cells using telomerase had 1%-3% of the TERRA expression levels of ALT cells. AV and LV expression of recombinant TERRA in telomerase positive cells showed a 1.3-2.6 fold increase in TERRA levels, and a decrease in TA of 25%-58%. Dominant-negative or small hairpin RNA (shRNA) viral expression against human telomerase reverse transcriptase (hTERT) results in senescence, not induced by TERRA expression. Population doubling time, cell viability and TL (telomere length) were not impacted by ectopic TERRA expression. Clonal growth was reduced by TERRA expression in TA but not ALT cell lines. ALT cells were not affected by treatments applied. Established cell models and tools may be used to better understand the role of TERRA in the cell, especially for targeting telomerase.
authors.affiliation: Institute of Cancer Research, Comprehensive Cancer Center, Medical University of Vienna, Borschkegasse 8a, Vienna 1090, Austria. theresa.kreilmeier@gmx.at.|Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna 1210, Austria. theresa.kreilmeier@gmx.at.
authors.forename: Theresa
authors.initials: T
authors.lastname: Kreilmeier
authors.affiliation: Institute of Cancer Research, Comprehensive Cancer Center, Medical University of Vienna, Borschkegasse 8a, Vienna 1090, Austria. doris.mejri@meduniwien.ac.at.
authors.forename: Doris
authors.initials: D
authors.lastname: Mejri
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27607, USA. marlene_hauck@ncsu.edu.
authors.forename: Marlene
authors.initials: M
authors.lastname: Hauck
authors.affiliation: Department for Companion Animals and Horses, University of Veterinary Medicine Vienna, Veterinärplatz 1, Vienna 1210, Austria. miriam.kleiter@vetmeduni.ac.at.
authors.forename: Miriam
authors.initials: M
authors.lastname: Kleiter
authors.affiliation: Institute of Cancer Research, Comprehensive Cancer Center, Medical University of Vienna, Borschkegasse 8a, Vienna 1090, Austria. klaus.holzmann@meduniwien.ac.at.
authors.forename: Klaus
authors.initials: K
authors.lastname: Holzmann
keywords: canine; enzyme inhibition; human; long non-coding transcript; telomerase; telomere; tumor cell lines; viral expression systems