Frequent Methylation of RASSF1 and RARB in Urine Sediments From Patients with Early Stage Prostate Cancer

Kristina Daniūnaitė¹, Artūras Berezniakovas¹, Feliksas Jankevičius^{2, 3}, Arvydas Laurinavičius^{2, 4}, Juozas R. Lazutka¹, Sonata Jarmalaitė¹

¹Faculty of Natural Sciences, Vilnius University, ²Faculty of Medicine, Vilnius University, ³Vilnius University Hospital Santariškių Klinikos, ⁴National Center of Pathology, Vilnius, Lithuania

Key words: prostate cancer; DNA methylation; urine sediments; RASSF1 gene, RARB gene.

Summary. Background. Prostate cancer (PCa) is the second most prevalent malignancy among males, characterized by high mortality rates. Aberrant DNA methylation in promoters of tumor suppressor genes is an early and frequent event during prostate carcinogenesis. Modern techniques allow a sensitive detection of DNA methylation biomarkers in bodily fluids from cancer patients offering a noninvasive tool for PCa monitoring. Our study aimed at the analysis of DNA methylation in urine sediments from PCa patients for the selection of most informative noninvasive biomarkers.

Material and Methods. Real-time methylation-specific polymerase chain reaction was used for the detection of methylated RASSF1, RARB, and GSTP1 genes in catheterized urine specimens from 34 patients with biopsy-proven early or medium stage PCa.

Results. At least one gene was methylated in urine sediments from 28 cases with PCa, with a sensitivity of the test reaching 82%. RASSF1 was methylated in 71% (24 of 34), RARB in 44% (15 of 34), and GSTP1 in 3% (1 of 34) of the specimens. High level of methylation (≥50%) in RARB and RASSF1 genes was detected in 40% and 20% of cases, respectively. A significant association was observed between high level of RARB methylation and Gleason score (P=0.01), while methylation of at least one gene occurred more frequently in urine DNA of older patients (P=0.02).

Conclusions. Results of our study show a high sensitivity of DNA methylation biomarkers, especially RASSF1 and RARB, for the early and noninvasive detection of PCa.

Correspondence to S. Jarmalaitė, Faculty of Natural Sciences, Vilnius University, Čiurlionio 21, 03101 Vilnius, Lithuania. E-mail: sonata.jarmalaite@gf.vu.lt

Received 11 November 2010, accepted 17 March 2011