Australian researchers have discovered how massive DNA molecules called neochromosomes that appear in some tumours are stitched together from other parts of the genome “like Frankenstein’s monster”.
Neochromosomes are giant extra chromosomes found in up to 3% of all cancers, most commonly in liposarcomas (tumours of fatty tissue), soft tissue tumours and some brain and blood cancers. They are large and harbour extra copies of cancer-causing “oncogenes”.
The research, published in Cancer Cell, showed that neochromosome formation is triggered by spontaneous and catastrophic “explosions” of chromosomes. The shattered relics reassemble haphazardly, followed by a genetic frenzy of amplification and deletion. Genes that are important for cancer development become massively amplified, assuring the cancer’s survival.
“We showed that chromosome 12 shatters and its remnants form a ring of DNA in a haphazard fashion,” said A/Prof Tony Papenfuss of the Walter and Eliza Hall Institute and the Peter MacCallum Cancer Centre. “As cells divide, and the circular chromosomes get copied and pulled into different cells, a constant abnormal morphing takes place. Small circles gradually become giant circles, progressively amplifying certain genes in what appears to be a selective process.
“The growing giant also sucks in DNA from all parts of the genome. At a...
