New indicator of prostate cancer discovered
11 February 2009
Researchers from the University of Michigan Comprehensive Cancer
Center have discovered that the presence of the chemical sarcosine
appears to indicate aggressive prostate cancer.
The finding could lead to a simple test that would help doctors
determine which prostate cancers are slow-growing and which require
immediate, aggressive treatment. Results of the study appear in the Feb.
12 issue of Nature.
Rapid advances in medical diagnostics are producing a range of
potential prostate cancer tests that could replace the unreliable PSA
test. MTB Europe reported on a trial of gene-based molecular diagnostic
test for prostate cancer in August 2008 (see
cancer molecular test ready for commercialization).
“One of the biggest challenges we face in prostate cancer is
determining if the cancer is aggressive. We end up overtreating our
patients because physicians don’t know which tumours will be
slow-growing. With this research, we have identified a potential marker
for the aggressive tumours,” says senior study author Arul Chinnaiyan,
MD, PhD, director of the Michigan Center for Translational Pathology and
SP Hicks Endowed Professor of Pathology at the U-M Medical School.
The researchers looked at 1,126 metabolites across 262 samples of
tissue, blood or urine associated with benign prostate tissue, early
stage prostate cancer and advanced, or metastatic, prostate cancer.
They mapped the alterations in metabolites and identified about 10
that were present more often in prostate cancer than in the benign cells
and were present most often in the advanced cancer samples.
“When we’re looking at metabolites, we’re looking several steps
beyond genes and proteins. It allows us to look very deeply at some of
the functions of the cells and the biochemistry that occurs during
cancer development,” says Chinnaiyan, a Howard Hughes Medical Institute
One metabolite in particular, sarcosine, appeared to be one of the
strongest indicators of advanced disease. Levels of sarcosine, an amino
acid, were elevated in 79% of the metastatic prostate cancer samples and
in 42% of the early stage cancer samples. Sarcosine was not found at all
in the cancer-free samples.
In the study, sarcosine was a better indicator of advancing disease
than the traditional prostate specific antigen, or PSA, test that is
currently used to monitor or screen for prostate cancer. Sarcosine was
detected in the urine, which has researchers hopeful that a simple urine
test could be used.
In addition, the researchers found that sarcosine is involved in the
same pathways that are linked to cancer invasiveness. This suggests
sarcosine as a potential target for future drug development.
“This research gets at characterizing the chemical complexity of a
sample of blood. In the future, this science will drive how doctors make
treatment recommendations for their patients,” says study author Dr
Christopher Beecher, professor of pathology at the University of
Michigan Medical School.
Results are preliminary at this point and will need years of further
testing and development before this technology would be available for
Nature, Vol. 457, No. 7231, pp. 910-915, Metabolomic profiles
delineate potential role for sarcosine in prostate cancer progression
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