Fig. 3

Models of how extrachromosomal circular DNA is formed. a In response to environmental changes, cells could repair DNA strand break through removing the damaged segments. After then, the small DNA segments could form circular DNA. b Chromothripsis is a single-step catastrophic event that drives chromosome breakage and end-to-end chromosomal fusion, and serves as the underlying driving force linked to local DNA rearrangements and extrachromosomal circular DNA. c The episomes are autonomously replicating submicroscopic precursors of extrachromosomal circular DNA. In cell, The DNA recombination processes can generate the recombinant episome that contains a segment of chromosomal DNA, such as c-Myc-containing DMs. d The BFB cycle involves anaphase bridge formation due to the presence of dicentric chromosomes, followed by bridge breakage, which generates a variety of chromosomal aberrations, including extrachromosomal circular DNA