Micronuclear extrachromosomal DNA limits tumor cell fitness in Nature Genetics study
In a Nature Genetics study using single-micronucleus sequencing and live-cell imaging of cancer cells alongside analyses of biopsies from patients with neuroblastoma, researchers investigated how extrachromosomal DNA (ecDNA) damage, mitotic segregation, and micronucleus formation are linked. The authors report that ecDNAs are a major source of micronuclei following their damage, particularly under replication stress, which promotes mitotic ecDNA clustering, asymmetric inheritance, mis-segregation into micronuclei, and reduced transcriptional output. Single-micronucleus sequencing revealed that multiple distinct ecDNA species coalesce within individual micronuclei, and cells inheriting ecDNA-positive micronuclei display impaired proliferative capacity and are more likely to undergo cell death.
In patients with MYCN-amplified neuroblastoma, higher frequencies of ecDNA-positive micronuclei at diagnosis were associated with improved overall survival, and the authors report that together these findings identify ecDNA mis-segregation as a mechanism that limits tumor fitness.
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