The fountain of youth that keeps the immortal cancer cells can be disabled by a mutated enzyme, the researchers say.
The key cancer cell immortality are the telomeres of the cell, repetitive stretches of DNA at the ends of chromosomes that can protect the chromosomes when they divide. Researchers have learned that telomeres get shorter and shorter each time a cell divides; Once they are gone, the cell dies. Cells in semen, bone marrow and other tissues that divide are frequently an enzyme called telomerase that prevents telomeres shrink. Because cancer cells are also telomerase, scientists have suspected that the enzyme allows cancer cells to continue to divide without dying. Many laboratories test whether compounds which block the enzyme can slow tumor growth.
oncologists William Hahn, Robert Weinberg and colleagues at the Whitehead Institute in Cambridge, Massachusetts, mutated gene for part of the enzyme and inserted into human cells cultured from tumors of the colon, ovary and breast. The mutant unit linked with other building blocks to create a telomerase enzyme that dud supplanted the native enzyme. In seven weeks, all cells have stopped dividing, scientists report in October Nature Medicine . In another indication that cancer cells persist because they maintain their telomeres, the cells that began with longer telomeres in the experience lived longer than those with shorter telomeres.
The results are "an exciting step forward in validating telomerase" as a drug target against cancer, said Louis Zumstein, a molecular biologist at Introgen Therapeutics in Houston, Texas. But a drug antitelomerase would be no miracle solution, as it would allow cancer cells to continue dividing until their telomeres were gone. such latency, Hahn said, could allow cancer cells to develop resistance to a drug finding another way to maintain their telomeres. the wisest approach, Zumstein said, would be to combine a telomerase inhibitor with additional drugs.
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