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Stem Cells found in Prostate may be involved
in Cancer
Newswise — A new type of stem cell
discovered in the prostate of adult mice can
be a source of prostate cancer, according to
a new study by researchers at the Herbert
Irving Comprehensive Cancer Center at
Columbia University Medical Center and
NewYork-Presbyterian Hospital.
Led by Michael Shen, Ph.D., professor of
medicine and genetics and development at
Columbia University Medical Center, the
researchers found the rare stem cells,
called CARNs (which stands for
“castration-resistant Nkx3.1-expressing
cells”), within the ducts inside the mouse
prostate.
The stem cells are involved in regenerating
prostate tissue, but the researchers also
found that CARNs can give rise to cancer if
certain tumor suppressor genes in the cells
are inactivated.
The findings will be published in an advance
online edition ofNature at
1 p.m. ET on Wednesday, September 9, 2009.
Understanding which cells in the prostate
give rise to cancer may help researchers
develop better treatments for prostate
cancer. But the identity of these cells of
origin for prostate cancer has been
controversial.
Recently, some researchers have proposed
that prostate cancer may arise from normal
adult stem cells, since stem and cancer
cells share several characteristics.
But the
only stem cells previously described in the
prostate are basal cells, which have been
considered to form a “support” layer for the
luminal cells that make prostate secretions.
However, since prostate cancers are filled
exclusively with cells that have features of
luminal cells, it has been unclear how
cancer might arise from basal cells.
The new study may resolve this conundrum
because the newly discovered adult stem
cells are also luminal cells.
“Previous
research suggested that prostate cancer
originates from basal stem cells, and that
during cancer formation these cells
differentiate into luminal cells,” said Dr. Shen.
“Instead, CARNs may represent a
luminal origin for prostate cancer.”
And indeed, the researchers found that CARNs
in mice can give rise to prostate cancers,
after the cells lose the activity of PTEN, a
gene that is frequently mutated in human
prostate cancers.
The results do not mean, however, that CARNs
give rise to “cancer stem cells,” cells
inside a tumor that are capable of
regenerating the cancer from a single cell.
“The relationship between the normal
prostate stem cells and potential cancer
stem cells is not known yet,” said Dr. Shen.
“And even the existence of cancer stem cells
in prostate tumors is not established.”
Also unclear is whether CARNs exist in the
normal human prostate and if human prostate
cancers originate from these CARNs. Dr.
Shen’s lab is now looking to investigate
these issues.
This work was supported by grants from the
National Institutes of Health, the
Department of Defense Prostate Cancer
Research Program, and the National Cancer
Institute Mouse Models of Human Cancer
Consortium.
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