Fig. 7.

Diagram depicting the theoretical hypothesis that how the small-size eccDNAs accelerate the cancer progression. Tumor cells with instable genome can generate massive small-size eccDNAs carry random genomic segments which will be segregated randomly to daughter cells as the cell division. Host cells harboring “good” eccDNAs obtain growth advantages or increased aggressive features, whereas the inheritance of “bad” eccDNAs accelerates cell apoptosis or induces cell death. Silenced eccDNAs with no function (“passenger” eccDNA) have no effect on the host cells. This cyclic process may drive cells to evolve to malignant cells