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5 December 2013 11:26 am ,
Vol. 342 ,
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
- 5 December 2013 11:26 am , Vol. 342 , #6163
- About Us
Immortality Without Tumors
28 December 1998 6:30 pm
In ancient Greece, immortality was the province of gods who spun the length of each lifetime. The myth has a kernel of truth, because the ends of chromosomes are protected by specialized stretches of DNA called telomeres. Once these are snipped too much by imperfect copying, a cell goes into senescence and stops dividing. Now two reports show that, with the help of an enzyme called telomerase, human cells can divide forever in the laboratory without turning cancerous. The findings, reported in the January issue of Nature Genetics, could ease the way to new treatments for burn victims, diabetics, and patients with other diseases.
Researchers hoped that adding telomerase would keep cells dividing long enough to replace tissues lost to injury or disease. Normal cells often have proved impractical because they can only divide a limited number of times in culture, and once returned to the body they're often too old to do much good. The limitation may be that normal cells do not produce active telomerase, which can rebuild the telomeres and keep cells from becoming senescent.
In fact, about a year ago, Jerry Shay and his colleagues at the University of Texas Southwestern Medical Center in Dallas showed that adding the enzyme to normal connective tissue cells called fibroblasts extends their life-span (ScienceNOW, 13 January 1998). These cells have now lived three times longer than normal in the lab, and they are still going strong. But because cancer cells contain telomerase and also live forever, scientists worried that the newly immortal cells would become malignant when implanted in humans.
To allay that fear, Shay and his colleagues checked the newly immortal cells for other telltale traits of cancer cells. They found none. Unlike cancer cells, the telomerase-containing fibroblasts stopped growing when deprived of blood serum and a solid surface they can adhere to; they also stopped growing when their DNA was damaged or when they brushed up against other cells; and, also unlike cancer cells, they contained the correct number of chromosomes. Likewise, Choy-Pik Chiu and her co-workers at Geron Corp. in Menlo Park, California, did similar tests--with similar results--on both fibroblasts and retinal cells that had been immortalized by telomerase addition. The Geron group also showed that the death-defying cells fail to form tumors, either in culture dishes or in susceptible mice.
"The results are fascinating," says cancer biologist Al Klingelhutz of the Fred Hutchinson Cancer Research Center in Seattle. But he and other experts caution that while the immortal cells retain growth controls in culture, they may still be predisposed to cancer in humans. Nevertheless, says cancer biologist John Sedivy of Brown University, so far the prospect of using telomerase-immortalized cells in new therapies "looks extremely promising."