by Danny Hooley
The study, "A miR-34a-Numb Feedforward Loop Triggered by Inflammation Regulates Asymmetric Stem Cell Division in Intestine and Colon Cancer," was published Thursday in the online journal Cell Stem Cell.It's broken down here, in terms slightly more digestible by laypersons, in the blog Science 2.0:
Duke scientists grew two sets of cellular "miniguts" on culture dishes and stimulated them with inflammatory factors. The miniguts on the left are normal. But on the right, the deletion of a MicroRNA called miR-34a causes stem cells (green markers in the top right image and red markers in the bottom right image) to divide out of control. This causes the minigut to bloat into a cancerous sphere.
The conclusion is that miR-34a is "the good guy," that "shows up only when things go wrong, according to Shen.
To find out, Shen and his colleagues deleted miR-34a from the genetic code of some mice. But nothing happened.
"It really puzzled the scientific community," said Shen. "Usually if something is important and you delete it, it causes a problem."
In the latest study, however, the problem showed up when the mice's tissues became inflamed. Without any microRNA miR-34a, their stem cells quickly grew out of control and formed many tumor-like structures.
With a test to look for elevated levels of miR-34a, researchers could create an early warning system to catch cancers in their youthful stages when they are much easier to cure. And as a possible treatment for late-stage cancer, researchers are trying to get the cancer cells to express miR-34a again. This would stop the tumor cells from gaining the flexibility to revert back to stem cells and allow doctors to wipe them out once and for all.