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Abstract Telomeres are the protective, nucleoprotein structure at the ends of linear eukaryotic chromosomes. The accurate measurement of both telomeric length and composition of individual telomeres in mammalian cells has been challenged by the length and repetitive nature of telomeres. With the advent of third generation sequencing technologies, it is now technically possible to sequence entire telomeres and map them to individual chromosome arms. Here, we report a reliable method to enrich, sequence and analyze human telomeres using Oxford Nanopore Technologies long-read sequencing. To enrich for telomeric sequences we combine the ligation of adapters complementary to the telomeric G-overhang with restriction enzyme digest to sequence the telomeric C-strand and part of the adjacent subtelomere. The subtelomeric information is harvested to map individual telomeric reads to specific chromosome arms and even alleles. We have measured bulk, chromosome-arm-specific telomere length dynamics during cellular aging of cultured primary cells and in a patient-derived aging cohort. To address the impact of the telomere maintenance mechanism on telomere length and composition, we have sequenced matched pairs of fibroblasts and induced pluripotent stem cells, as well as five well-established telomerase- and ALT-positive cancer cell lines. Our results suggest that based on nanopore telomere long-read sequencing ALT-positive cells can be easily discriminated from normal and telomerase-positive cancer cells. Further, telomere sequencing allows to evaluate the methylation status of the subtelomeric CpG islands adjacent to telomeres. In summary, nanopore telomere long-read sequencing allows to measure the length and composition of individual telomeres and their mapping to specific chromosome arms. Telomere long read sequencing methods will be valuable tools to study telomere biology during aging and cancer. Citation Format: Tobias T. Schmidt, Carly Tyer, Preeyesh Rughani, Candy Haggblom, Jeff Jones, Xiaoguang Dai, Kelly A. Frazer, Fred H. Gage, Sissel Juul, Scott Hickey, Jan Karlseder. Telomere dynamics in aging and cancer by nanopore long-read sequencing abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 1639.
Schmidt et al. (Fri,) studied this question.