The role of eccDNA in cancer is not a particularly new concept. However, studies like this are important to further elucidate cancer-promoting mechanisms. Additionally, the use of artificial eccDNA holds a lot of promise for genetic enhancement in many forms of life from humans, to livestock, to plants. Essentially, we could create artificial chromosomes which express useful genes or have inverted repeats which deliv…
Because they aren’t under the same selective pressure as normal chromosomes, the number of ecDNA molecules can be highly variable between daughter cells. This is one of the potential resistance mechanisms for a tumor. If you have a drug that targets a gene in the ecDNA, the tumor could only keep clones with a small number of ecDNAs during treatment. Then after the drug has cleared, the number of ecDNAs can then rise again.
When you lose the default 2 copy state, natural selection can follow non-Mendelian patterns.