Alterations to the switches that turn genes on or off occur early in the development of prostate cancer and could be used as biomarkers to detect the disease months or even years earlier.

DNA methylation patterns that could distinguish between healthy and cancerous tissue have been discovered and similar biomarkers are being investigated that could distinguish between patients with varying levels of recurrence risk

Scientists at the Mayo Clinic (Rochester, MN, USA) investigated the promoter hypermethylation as diagnostic markers to detect malignant prostate cells and as prognostic markers to predict the clinical recurrence of prostate cancer. DNA was isolated from prostate cancer and normal adjacent tissues and after bisulfite conversion, methylation of 14,495 genes was evaluated using the Infinium Methylation27 microarrays (Illumina, San Diego, CA, USA) in 238 prostate tissues. The patients included people who remained cancer-free after treatment, those who had a localized tumor recurrence, and those whose cancer spread.

The scientists found distinct methylation alterations that corresponded to whether a patient had a slow-growing tumor known as an indolent tumor, or had a more aggressive one. If physicians can determine what type of tumor patients have, they can avoid exposing patients with indolent tumors to unnecessary treatment, and can treat those with aggressive tumors earlier and more effectively.

Krishna Donkena, PhD, a Mayo Clinic molecular biologist, and senior author of the study said, "Our approach is more accurate and reliable than the widely used prostate-specific antigen (PSA) test. The PSA test detects any prostate abnormality, whether inflammation, cancer, infection or enlargement, while the DNA methylation changes are specific to prostate cancer."

Currently, the test relies on microarray or gene chip technology that assesses methylation status of genes across an entire genome. The scientists are trying to generate more economical custom microarray to look specifically at only the genes that predict the development of prostate cancer or recurrence. The study was published on May 15, 2012, in the journal Clinical Cancer Research.

Related Links:
Mayo Clinic
Illumina