Stem Cell May Give Rise To Prostate Cancer
Researchers have identified a new type of stem cell that may give rise to at least some types of prostate cancer, according to a study released Wednesday by scientists at Columbia University Medical Center and New York-Presbyterian Hospital.
According to researchers, these so-called luminal cells, which secrete compounds used in the prostate, may be a potential new source for prostate tumors.
The findings of the study, which was conducted with mice, are only experimental, but could explain at least some types of prostate cancer and ultimately pave the way to new treatments.
The researchers said the discovery supports evidence that cancers can be caused by changes in stem cells — precursor cells that develop into and replenish the body’s various tissues.
The researchers found the rare stem cells, called CARNs, or "castration-resistant Nkx3.1-expressing cells", within the ducts inside the prostate of mice. In addition to their role in regenerating prostate tissue, CARNs can also give rise to cancer if certain tumor suppressor genes in the cells are inactivated, the researchers found.
The identity of these cells of origin for prostate cancer has been controversial. Some scientists have recently theorized that prostate cancer may arise from normal adult stem cells, since stem and cancer cells share several characteristics. However, 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 mystery 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. Michael Shen, Ph.D., professor of medicine and genetics and development at Columbia University Medical Center.
"Instead, CARNs may represent a luminal origin for prostate cancer,” said Dr. Shen, the study’s lead researcher.
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.
However, those results do not mean 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," Dr. Shen said.
"And even the existence of cancer stem cells in prostate tumors is not established."
Dr. Shen’s lab is now investigating whether CARNs exist in the normal human prostate, and if human prostate cancers originate from these CARNs.
The study published in an advance online edition of Nature on September 9.
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