What do humans have in common with yeast -- that lowly, single-celled organism known best for its role in making beer and bread?

Plenty, according to researchers at Seattle's Fred Hutchinson Cancer Research Center, who have found that humans and yeast share a protein that appears to play a key role in regulating cell growth.

Ronald Reeder, Ph.D., a member of the Hutchinson Center's Basic Sciences Division, heads the group that published the results of this work earlier this week in the Proceedings of the National Academy of Sciences (Early Edition No. 12). Co-authors on the paper are research associate Beth Moorefield, Ph.D., and biocomputing specialist Elizabeth Greene, Ph.D., both of the Hutchinson Center. The protein, called Rrn3, may play a pivotal role in the chain of events that determines how fast cells grow.

"For a protein to be functionally conserved from yeast all the way up to humans implies there must be a reason that it has been preserved from an evolutionary standpoint," Reeder says. "We know that if you don't have this protein, you don't grow. Even if there are other mechanisms that human cells use to regulate cell growth, the fact that this one is so well conserved in humans means it's an important piece of the puzzle in our understanding of growth control."

While Reeder and colleagues are primarily excited about this fundamental new understanding of the molecular mechanisms that trigger cell growth, the discovery that Rrn3 functions in humans as well as yeast may have several long-range benefits.

This regulatory molecule may be a unique drug target, as disabling it might halt the growth of cancer cells. The protein also might be used as a biomarker to develop highly sensitive cancer-screening methods, as the activity of Rrn3 is expected to mirror the rate of cell growth throughout the body.

"If you were looking at the thymus or the liver, for example, and wanted to distinguish cells that were doing normal things vs. ce
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Contact: Kristen Woodward
kwoodwar@fhcrc.org
206-667-5095
Fred Hutchinson Cancer Research Center
13-Apr-2000