The formation mechanism and homeostasis of extrachromosomal DNA.

Extrachromosomal DNA, referred to as extrachromosomal DNA (ecDNA), was found in most cancers and nearly absent in normal cells. The properties of ecDNA enable tumor cells to be more responsive to various environments. The non-Mendelian genetic mechanism of ecDNA could arouse increasing tumor heterogeneity. Besides, ecDNA would promote tumor invasiveness and provide resistance mechanisms associated with poorer survival consequences. Furthermore, ecDNA could profoundly impact oncogene activation, genome instability, tumor heterogeneity, etc. Consequently, they may offer potential possibilities for tumor diagnosis and therapeutics. We primarily reviewed the classification, several primary formation mechanisms, homeostasis maintenance and frontier progress of ecDNA and late emphasized its fundamental roles in tumorigenesis and put forward some new insights.