Authors: Georgia Patey, Future Science Group
A set of RNA molecules that are detectable in tissue and urine samples of individuals with prostate cancer but not in normal healthy individuals has been identified by researchers at Sanford-Burnham Medical Research Institute (CA & FL, USA). The researchers have proposed that this group of RNA molecules could serve as a better prognostic marker for prostate cancer than those currently utilized.
Prostate cancer is the second most common type of cancer in US men, and the second-leading cause of cancer death in men. It is estimated that one in seven US men will develop prostate cancer over the course of his lifetime and one in 36 will die from the disease. Many men with prostate cancer have indolent disease, and thus it is very important not only to identify those men with prostate cancer, but also to distinguish those men who will benefit from surgical or other aggressive treatment from those who will not.
Currently, detection and monitoring of prostate cancer involves testing for high concentrations of prostate-specific antigen (PSA) in blood samples. If high levels of PSA are detected, this is often followed by a biopsy to confirm the presence of cancer and to determine how aggressive it is.
“While elevated PSA can be an alert to a lethal cancer, it can also detect less aggressive cancers that may never do any harm,” commented Vipul Patel of Florida Hospital in Orlando (FL, USA). “Moreover, only 25% of men with raised PSA levels that have a biopsy actually have prostate cancer. Prostate cancer needs to be screened for; we just need to find a better marker.”
The researchers believe that they may have identified a group of long noncoding RNAs (lncRNA) that could serve as better prognostic markers for prostate cancer. lncRNAs were long thought to be simply nonfunctional noise in the genome, but are increasingly being recognized as regulators of normal cellular development and have been implicated in a number of diseases, including cancer.
“We have identified a set of lncRNAs that appear to have an important role in prostate cancer diagnostics,” commented Ranjan Perera, Scientific Director of Analytical Genomics and Bioinformatics at Sanford-Burnham’s Lake Nona campus in Orlando. “The findings advance our understanding of the role of lncRNAs in cancer biology and, importantly, broaden the opportunity to use lncRNAs as biomarkers to detect prostate cancer.”
In the study, lncRNAs were profiled in three distinct groups: human prostate cancer cell lines and normal prostate epithelial cells; prostate adenocarcinoma tissue samples and matched normal tissue samples; and urine samples from patients with prostate cancer or benign prostate hypoplasia, and normal healthy individuals. The results of the investigation found that lncRNAs were elevated in prostate cancer patient samples, but not in the normal healthy individuals or those with benign prostate hypoplasia.
A certain lncRNA, PCA3, was recently commercialized as a urine test to identify those men that should undergo a repeat prostate biopsy. However, discrepancies between PCA3 levels and clinicopathologic features have been found, according to Perera. Indeed, in this study, PCA3 was detected in some but not all of the study samples, demonstrating the need to combine more than one biomarker to potentially increase specificity and sensitivity of the test.
“There is a tremendous unmet clinical need for better noninvasive screening tools for early detection of prostate cancer to reduce the overtreatment and morbidity of this disease,” added Patel. “Our findings represent a promising approach to meet this demand.”