Over the years researchers have made tremendous strides in the understanding and treatment of cancer by searching genomes for links between genetic alterations and disease. Most of these studies have focused on the portion of the human genome that encodes protein – a fraction that accounts for just 2 percent of human DNA overall. Yet the vast majority of genomic alterations associated with cancer lie outside protein-coding genes, in what traditionally has been derided as "junk DNA." Researchers today know that "junk DNA" is anything but – much of it is transcribed into RNA, for instance -- but finding meaning in those sequences remains a challenge. Now a team led by Lin Zhang, Ph.D., research associate professor in the Department of Obstetrics and Gynecology at the Perelman School of Medicine at the University of Pennsylvania (Penn), has mined those sequences to identify a non-protein-coding RNA whose expression is linked to ovarian cancer. The study is published online in Cancer Cell. Supported by the Basser Research Center for BRCA in Penn's Abramson Cancer Center, Dr. Zhang and his team built a DNA copy number profile for nearly 14,000 long non-coding RNAs (lncRNAs) (image), across 12 cancer types, including ovarian and breast cancers -- the two major BRCA-related cancers. They found that the number of copies of lncRNA genes on a chromosome consistently changes in 12 different cancer types and lncRNA genes are widely expressed in cancer cells. What these non-protein-coding RNAs do is still relatively unknown. However, given their vast numbers in the human genome, researchers believe that they likely play important roles in normal human development and response to disease.
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