Prostate Cancer Urine Test Based on Gene Fusion

A newly discovered gene fusion is highly expressed in a subset of prostate cancers. This might lead to more accurate tests for prostate cancer.

The new fusion occurs when the genes are being copied into RNA. The two genes, SLC45A3 and ELK4, reside next to one another on the chromosome in normal and prostate cancer cells. However, when the genes are copied into RNA in the prostate cancer cells, they frequently generate a single RNA message that fuses information from both genes. The diagnostic implications are significant because these types of genetic chimera occur at significantly higher levels in abnormal tumor cells.

The SLC45A3-ELK4 gene fusion is detectable at high levels in the urine of some men at risk for prostate cancer. This could mean that these men will be detected by a simple urine test. The gene fusion biomarker is a different type of fusion than scientists have found in cancer previously and may represent an entirely new mechanism that cancer cells use to outgrow their healthy neighbors.

"We think this is going to be a potentially important diagnostic marker in prostate cancer," said Dr. Mark A. Rubin, the Homer T. Hirst Professor of Oncology in Pathology, professor of pathology and laboratory medicine, and vice chair for experimental pathology at Weill Cornell Medical College (New York, NY, USA). "PSA testing is inadequate. PSA detects men with cancer but also many men with benign conditions. As we have seen recently from two major studies on PSA screening, for every 50 men with a positive PSA screening, only one man's life is saved. We urgently need biomarkers to detect clinically significant prostate cancer."

Dr. Rubin's team is working with a company to develop a urine test for prostate cancer using a chromosome-based gene fusion called TMPRSS2-ERG that the team discovered previously while working with colleagues at the University of Michigan (Ann Arbor, MI, USA). Dr. Rubin anticipates that the newly discovered SLC45A3-ELK4 gene fusion may be added to that urine test in the future to increase its accuracy and to help determine the level of response to certain nonsurgical systemic treatments. The TMPRSS2-ERG urine test is being evaluated in multiple early clinical trials in the United States and Europe.

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Weill Cornell Medical
University of Michigan