Topoisomerase IIIα controls alternative lengthening of telomeres.

ABSTRACT: Alternative lengthening of telomeres (ALT) is a homologous recombination-dependent telomere elongation mechanism utilized by at least 10%-15% of all cancers. Here, we identify that the DNA topoisomerase, topoisomerase III⍺ (TOP3A), is enriched at the telomeres of ALT cells but not at the telomeres of telomerase (Tel)-positive cancer cells. We demonstrate that TOP3A stabilizes the shelterin complex in ALT cancer cell lines but not in Tel cells and that long non-coding telomeric-repeat containing RNA (TERRA) enrichment at telomeres depends on TOP3A. TOP3A also promotes the generation of single-stranded telomeric C-strand (ssTeloC) DNA, a recently discovered marker for ALT. Additionally, we find that inducing break-associated TOP3A-DNA-protein crosslinks in ALT cells suppresses TERRA enrichme

SUBMITTER: Khandagale P 

PROVIDER: S-EPMC12451542 | biostudies-literature | 2025 Aug

REPOSITORIES: biostudies-literature