Testing urine for sarcosine may give new insights into prostate cancer diagnosis and progression
US researchers have identified a compound in urine that could be used to detect prostate cancer - and also to distinguish between benign and invasive forms of the disease. Levels of sarcosine - the methylated form of the amino acid glycine - were found to be higher in the urine of prostate cancer sufferers, particularly when the cancer cells are more likely to spread to other organs.
Prostate cancer is one of the most common cancers diagnosed amongst men, but tracking the progress of the disease is often difficult. A typical diagnosis relies on a blood test for a specific protein called PSA (prostate-specific antigen) in blood, which is followed by a biopsy.
’But not all prostate cancers are created equal,’ says John Wei, a urologist who worked on the project. ’Some are slow growing and others are very aggressive - and it’s not always easy to separate the wheat from the chaff.’ This can sometimes lead to prostate cancer sufferers being over-medicated, he says.
Sarcosine was identified as a potential biomarker to spot prostate cancer after Arul Chinnaiyan and colleagues at the University of Michigan Medical School in Ann Arbor, US, characterised over 1,100 different compounds from prostate tissue, blood and urine. From this huge pool, they found six compounds that were directly associated with more severe forms of the disease.
Although further trials will be required, Chinnaiyan hopes that measuring either sarcosine or a combination of the six compounds could provide a non-invasive solution to getting a snapshot of how far the disease has progressed.
’There is another interesting aspect to this research,’ Chinnaiyan adds. ’Our findings indicate that sarcosine may be involved in the biology of cancer aggressiveness and invasiveness.’
This was demonstrated when the team added sarcosine to benign prostate cancer cells, turning them into invasive ones. ’This suggests to us that the process of sarcosine production may be a novel avenue for investigating new treatments,’ Chinnaiyan adds.
John Neate, chief executive of UK-based Prostate Cancer Charity, is enthusiastic about the work, but warns that there is still much research to be done before this can become a reliable diagnostic tool.
’It is too soon to say if the results of this study are a blind alley or a breakthrough but so far the results are promising enough for research to continue,’ Neate says. ’Men need progress in this kind of research, especially into the prostate cancers that can kill.’
A Sreekumar et al, Nature, 2009, DOI:10.1038/nature07762