Brain tumors may grow by causing brain cells to reset

A common type of brain tumor may be caused by mature adult cells being genetically “rewound” to a more immature state, according to a study in the journal Science.

The discovery could pave the way for improved brain cancer treatments. The cancer that was studied, called glioblastoma multiforme, is the most common type of brain tumor. It is also the most aggressive.

Researchers had previously thought that the tumors were generated by neural stem cells gone awry rather than adult cells, which were not thought to have a natural ability to revert to an earlier state of development. (The 2012 Nobel Prize in Medicine was given in part to researchers who discovered an artificial way of causing cells to revert to such an earlier stage.)

In the new study, researchers from UC San Diego led by geneticist Dinorah Friedmann-Morvinski used viruses to ferry DNA known to cause cancer -- called oncogenes -- into the brain cells of mice.

Once the oncogenes had become established in those cells, the researchers observed something astounding: Development happened in reverse. The oncogenes had caused a series of genetic changes that reverted the cells back to an earlier, undifferentiated state, a state from which tumors are known to arise because the cells are able to rapidly proliferate.

The findings explain why small numbers of cells left behind from a resection surgery or chemotherapy might lead to relapse, as a seemingly insignificant number of cells can lead to a full-blown tumor after reverting to this earlier state.

The results also suggest that stopping the regression of adult cells to undifferentiated cells may provide a new target for cancer therapy.

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