Urinary Biomarker Found for Prostate Cancer Risk

A protein in urine could be a reliable marker for prostate cancer assessment and has advantages over the standard prostate specific antigen (PSA) test.

The protein, microseminoprotein-beta (MSMB), which is produced by normal prostate cells and secreted into urine from semen, regulates cell apoptosis or programmed cell death and is linked to an increased risk of developing prostate cancer.

In a multi-institute collaborative study, led by scientists from the Institute of Cancer Research, (CRUK; Cambridge, UK), tissue, urine and blood samples were analyzed from cohorts of prostate cancer patients. Urinary PSA and MSMB levels were determined by enzyme-linked immunoassays (ELISA) and normalized to creatinine. Samples from 133 of the patients were made into a tissue microarrays (TMA) containing multiple cores from normal/benign regions (>3), prostatic intraepithelial neoplasia (PIN) and at least two distinct regions of tumor for each patient. Genotyping was performed on DNA extracted from blood samples.

The urinary levels of MSMB were determined in 215 men with no history of prostate disease and 89 men with prostate cancer. Consistent with the association in prostate tissue there was a significant decrease in urinary MSMB in men with tumors compared with men with no history of prostate disease. No normal or tumorigenic tissues demonstrated any MSMB staining suggesting that at the protein level in tissue MSMB is highly prostate specific. In particular the tissues surrounding the prostate, such as urothelium, seminal vesicles and bladder muscularis propria layer showed no staining whereas adjacent benign prostate glands were heavily stained. MSMB demonstrated high levels of specificity and sensitivity particularly when compared to urinary PSA. There was a significant decrease in urinary MSMB with the high risk allele compared to the low risk allele.

Hayley Whitaker, Ph.D., the lead author, said, "Microseminoprotein-beta (MSMB), is easy to detect because it is found in urine and would potentially be a very simple test to carry out on men to identify those most at risk". The study was published on line on October 13, 2010, in the open access journal from the Public Library of Science, PLoS One.

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Institute of Cancer Research