"We are doing whole genome sequencing as opposed to more targeted sequencing because it's really necessary to identify these rearrangements which are so important in prostate cancer," Berger said.
The study, conducted by researchers from the Broad Institute, Dana-Farber Cancer Institute and Weill Cornell Medical College, appears in the Feb. 10 issue of Nature.
Until recently, such DNA rearrangements were known to be important in blood cancers such as lymphoma and leukemia, said William Phelps, program director for Translational and Preclinical Cancer Research at the American Cancer Society. However, it's only more recently that researchers have started uncovering the importance of that type of genetic alteration in solid tumors such as breast and now, prostate cancers, he said.
Here's one way to conceptualize the alteration, Phelps said: "If the genome was a book, instead of just looking for out-of-place letters or misspelled words, whole genome sequencing looks for whole paragraphs that are in the wrong place.
"Because [the researchers] sequenced everything, they were able to map not only individual base changes but also how whole genes or segments of the chromosomes had moved around," Phelps said. "By sequencing everything and comparing the normal DNA (in white blood cells), they could see that not only were there individual base changes in the genes, but the genes themselves had been reshuffled in the tumor as part of the process of becoming cancer," he explained.
"If we could use those changes as a diagnostic tool that would be tremendously valuable," he added.
Whole genome sequencing also enables scientists to look not only at "coding" genes, but also "noncoding" DNA around the genes that was once thought to be "junk" but is now known to play an important regulatory role within cells, Phelps said.
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