A small group of immune-regulating molecules, when overproduced even moderately, can trigger the blood cancers known as lymphomas, according to a new study led by scientists from The Scripps Research Institute (TSRI). The six “microRNA” molecules were already known to be overproduced in lymphomas and in many other human cancers, but no one had demonstrated that they can be the prime cause of such cancers—until now. The new study also identified the major biological pathways through which these microRNAs ignite and maintain cancerous growth. “We were able to show how this microRNA cluster can be the main driver of cancer, and so we now can start to think about therapies to combat its effects,” said TSRI Assistant Professor Changchun Xiao. Dr. Xiao was the senior investigator for the study, which was published online on August 6, 2013 in the EMBO Journal, a publication of the European Molecular Biology Organization. Discovered only in the 1990s, microRNAs are short molecules that work within virtually all animal and plant cells. Typically each one functions as a “dimmer switch” for one or more genes; it binds to the transcripts of those genes and effectively keeps them from being translated into proteins. In this way, microRNAs can regulate a wide variety of cellular processes. The focus of the new study was a cluster of six microRNAs known as miR-17~92, encoded by a single gene on chromosome 13. Studies of miR-17~92, including one from Dr. Xiao’s lab earlier this year, have shown that it controls various immune-related and developmental processes, depending on the type of cell in which it is expressed.
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