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In normal human cells, the nucleus contains 23 pairs of chromosomes that enclose the DNA. There are some natural processes that can damage DNA. For example, in chromothripsis, which occurs in some cancers, the chromosomes are broken and rearranged. Cells can also make mistakes in the DNA when making copies of it to imbue in new cells. Such processes could cause a small part of the DNA to break away from the main chromosome and form a circular structure that floats freely inside the nucleus. This is ecDNA.

One of the three studies identified various environmental factors, including smoking, exposure to certain substances, and genetic mutations, to be triggers of DNA damage that could lead to the formation of ecDNA.

They found that ecDNA is more prevalent in liposarcomas, brain tumours, and breast cancers. They also reported that the prevalence of ecDNA rose after treatments like chemotherapy.

If you see below image:

The basic physical and functional characteristics of ecDNA are shown in green text boxes. These underlie three important dynamic processes shown in blue text boxes. The consequences of these processes can lead to oncogene activation and/or tumor suppression and may also lead to new therapies and/or biomarkers indicated by large arrows. Possible mechanisms of formation and therapeutic strategies that require further investigation are marked by a ‘?’.

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