Researchers from Johns Hopkins and the University of Pennsylvania have uncovered another reason why the Myc protein – one of the most commonly activated proteins in cancer – is so dangerous. Myc can stop the production of at least 13 microRNAs, small pieces of nucleic acid that help control which genes are turned on and off.
A research team led by Joshua Mendell, assistant professor at the McKusick-Nathans Institute of Genetic Medicine, previously found that Myc could turn on one particular group of growth-promoting miRNAs in lymphoma cells. His team, along with Andrei Thomas-Tikhonenko’s lab at the University of Pennsylvania, recently analyzed over 300 miRNAs in human and mouse lymphoma cells.
Tsung-Cheng Chang, lead author of the latest study, said he was surprised to find that “lots of Myc turns everything off, not on.” His team also found that Myc was directly attaching to the lymphoma cell DNA at the miRNA genes – further evidence that the decrease in miRNA levels was due to Myc. Thomas-Tikhonenko’s team also re-introduced repressed miRNAs into Myc-containing cancer cells, which suppressed tumor growth in mice. This raises the possibility that a gene therapy approach could be effective in treating certain cancers.