Stem Cells May Be at Root of Cancer
New Research May Explain Why So Many Tumor-Fighting Treatments Now Fail
April 20, 2007 (Los Angeles) -- Are most current cancer treatments -- as
well as many in development -- aimed at eradicating the wrong cancer cells?
That's the position of some leading researchers, who say that cancer is,
fundamentally, a stem cell problem -- and that therapy should be targeted at
so-called cancer stem cells.
"The models we currently use to develop cancer treatments are
fundamentally flawed," says Max Wicha, MD, director of the University of
Michigan Comprehensive Cancer Center in Ann Arbor.
"Most approaches up to now are targeting the wrong population of
cancer cells," which explains why so many fail to produce a cure, he tells
At the annual meeting of the American Association for Cancer Research here
this week, Wicha moderated a session during which researchers discussed new
discoveries suggesting that stem cells in leukemia, breast, and colon cancer
are at the root of many tumors.
A Primer on Cancer Stem Cells
All stem cells -- regardless of their source -- share some general
properties: They can reproduce and make exact copies of themselves, they live
longer than ordinary cells, and they can give rise to other cells in our
Embryonic stem cells are a hot, if controversial, area of research. They are
at such an early stage of development that they have potential to become many
different types of cells, including those of the heart or brain, for
Adult stem cells, on the other hand, are generally limited to
differentiating into cell types of their tissue of origin. Under typical
conditions, for example, adult stem cells in liver tissue can only form liver
cells, Wicha explains.
In labs worldwide, scientists are working furiously to figure out how to use
both embryonic and adult stem cells to produce virtually unlimited quantities
of healthy cells to replace the damaged ones in patients suffering from
disorders ranging from Alzheimer's to Parkinson's disease.
Cancer stem calls are a perversion of other adult stem cells. "They are
cells that have the ability to reproduce themselves and develop into cancer
cells," Wicha says.
A New Model for Cancer
Wicha says that the current model of what causes cancer assumes that cells
become malignant after a series of mutations disables their genetic control
"In this theory, any cell that gets the right series of mutations can
become cancer," he says.
In the stem cell hypothesis, cancer is driven by specific cells that contain
stem cell properties, Wicha says. These cells then reproduce and replenish
Currently, most treatments target cancer cells, but not necessarily cancer
stem cells, he says. While the treatment may shrink the tumor and keep it in
check for a while, eventually, the untreated cancer stem cells proliferate into
cancer cells, leading to a return of the tumor and death, he says.