Mutant Stem Cells May Seed Cancer

摘要

Stem cells have acquired a golden glow in the past few years as a possible tool for reversing the damage diseases wreak on organs. Many researchers predict that stem cell transplants―whether derived from embryonic tissue or from adult cells that retain the flexibility to develop into various tissues―will someday repair hearts crippled by heart attacks or brains under attack by Alzheimer's or Parkinson's disease. But the very qualities that make these cells so attractive for medicine―especially their capacity to replicate ad infinitum―also hint at a dark side. Recent evidence suggests that they may be the source of the mutant cells that give rise to cancerous tumors and maintain their growth. Researchers have identified what they call "cancer stem cells" in blood cancers, such as leukemias, and in breast and brain cancers. The finding raises the possibility that the mutations that drive cancer development may have originated in the body's small supply of naturally occurring stem cells. Cancer stem cells resemble those normal cells in several ways. In particular, both types are self-renewing. This means that when they divide, one of the daughter cells differentiates into a particular cell type that eventually stops dividing, but the other retains its stem cell properties, including the ability to divide in the same way again.