Three American scientists received the Nobel Prize in medicine for discovering an enzyme that plays a key role in cellular health and aging. Their finding sparked a new line of research into possible treatments for age-related maladies, such as cancer, blindness and cardiovascular disease.
The prize, which includes a shared cash award of $1.4 million, was given to Elizabeth Blackburn of the University of California, San Francisco, Carol Greider of Johns Hopkins University School of Medicine and Jack Szostak of Harvard Medical School.
The scientists discovered the workings of telomerase, an enzyme that produces tiny units of DNA that seal off the tips of chromosomes. These DNA units, known as telomeres, act like the plastic caps at the ends of a shoelace, keeping the chromosomes from fraying and the genes inside them from unraveling.
Telomeres enable accurate cell division and also influence the number of times a cell divides, thereby determining its life span.
"Without telomerase we wouldn't be here -- it's vital to life," Dr. Blackburn said in an interview. "The tips of chromosomes wear down and telomerase helps to replenish them," keeping them at a proper length.
As we age, though, these caps lose their ability to protect. One result is that some cells go into a state known as senescence, where they are alive but stop dividing. Researchers believe this may contribute to aging.
The three scientists' work on unraveling the mysteries of the telomerase enzyme, which got started in the late 1970s, provided hope that life could be prolonged. It also led to an entirely new line of medical research into age-related conditions. For example, scientists are trying to reactivate telomerase to treat blindness, cardiovascular disease and neurodegenerative disease.
In most cases, it is healthy for cells to age and die. In fact, cancer is closely associated with cells that fail to follow the normal script for cell death and instead just keep reproducing.
That is why the discovery of telomerase has also led to new insights into cancer. A cancer cell divides continuously, and up to 90% of human cancers require telomerase to do so. Tumors somehow turn on the telomerase gene. Scientists hope to fight cancer by deactivating the enzyme. Geron Corp. GERN +2.52% Geron Corp. U.S.: Nasdaq $1.83 +0.04 +2.52% March 14, 2014 4:00 pm Volume (Delayed 15m) : 9.08M AFTER HOURS $1.83 0.00 0.00% March 14, 2014 7:48 pm Volume (Delayed 15m): 124,337 P/E Ratio N/A Market Cap $270.34 Million Dividend Yield N/A Rev. per Employee $16,638.1 03/12/14 Stocks to Watch: EPL Oil & Gas... More quote details and news » of Menlo Park, Calif., has launched clinical trials to see whether a telomerase inhibitor can fight lung, breast, pancreatic and other cancers.
But the scenario isn't that simple. "It means there's a trade-off between aging and cancer," said Dr. Szostak in an interview. "You can't turn on telomerase everywhere in the body in the hope of treating aging, because there will be the unintended consequence of causing cancer."
The earliest findings about telomerase were made not with any practical application in mind, but as a result of sheer curiosity. Scientists knew that the tips of chromosomes were somehow protected, but when they looked through a microscope all they saw was a blob.
Dr. Blackburn showed that simple, repeated DNA sequences make up the tips of each chromosome. She and Dr. Szostak then established that the DNA repeats stabilize chromosomes and prevent them from becoming damaged. The pair also speculated that there must be an enzyme that would do the job of adding the sequences to the tips of chromosomes.
In 1985, while a professor at the University of California, Berkeley, Dr. Blackburn and her then-graduate student, Dr. Greider, published a paper announcing the discovery of the enzyme telomerase.
Some of their key experiments were done with a pond-dwelling protozoa called tetrahymena. This single-celled organism was deemed to be the best test system because it contains some 40,000 chromosomes, far more than the 23 pairs of chromosomes contained in a human cell. Researchers later replicated the findings in human cells.
"This was the result of curiosity-driven, basic research," Dr. Greider said in an interview. In an era when research is increasingly focused on getting a specific, short-term payoff, "I consider [this award] to be a victory for fundamental science."
Dr. Blackburn is a native of Australia who has lived in the U.S. since 1975. She became a naturalized U.S. citizen in 2003 while retaining her Australian citizenship. Dr. Szostak was born in London, grew up in Canada and is now a U.S. citizen. Dr. Greider is a native of San Diego.
Write to Gautam Naik at email@example.com