new report from the University of Pennsylvania and Johns Hopkins University finds the Myc protein can stop the production of at least 13 microsRNAs – small pieces of nucleic acid that help control which genes are turned on and off.
The study also finds in several cases, re-introducing repressed miRNAs into Myc-containing cancer cells suppressed tumor growth in mice – this means it is possible that a gene-therapy approach could be effective in treating some cancers.
Researchers analyzed more than 300 miRNAs in lymphoma cells of humans and mice. They had previously found Myc could turn on one particular group of growth-promoting miRNAs in lymphoma cells. In the cells with high amounts of Myc protein, researchers found big changes in the quantities of at least 13 miRNAs.
When researchers took a closer look at the DNA of the lymphoma cells, they found Myc was directly attaching to the DNA at the miRNA genes.
“This study expands our understanding of how Myc acts as such a potent cancer-promoting protein,” lead researcher Joshua Mendell, Johns Hopkins University, was quoted as saying. “We already knew that it can directly regulate thousands of genes. Through its repertoire of miRNAs, Myc likely influences the expression of thousands of additional genes. Activation of Myc therefore profoundly changes the program of genes that are expressed in cancer cells.”
Researchers also reintroduced several repressed miRNAs into mouse lymphomas with high levels of Myc. When they measured the effect on the progression of lymphoma they found at least five of the miRNAs could stop cancer from growing.
Mendell says RNA-based therapies have had some success in animals and it is possible to find a wide range of miRNAs that can stop cancers in their tracks.
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