Evaluation of mir-203 Expression Levels and DNA Promoter Methylation Status in Serum of Patients with Endometrial Cancer

Background: Endometrial cancer (EC) is currently considered the fourth most frequent female cancer in Europe. In an attempt to achieve an early diagnosis, many studies have identified some putative biomarkers for gynecologic cancers, including circulating microRNAs (miRs) and aberrant promoter methylation status. Previous studies which have investigated miR-203 expression profiles in EC tissues and normal endometrial tissues concluded that miR-203 is regulated by methylation promoter. The aim of this study was to investigate the expression of miR-203 and promoter methylation levels in serum of EC patients and healthy controls (HC). Methods: Forty-five EC patients (64 +/- 12 years) and 30 HC (63 +/- 13 years) were enrolled before undergoing therapeutic procedures. RNA extraction from serum was performed with mirVana PARIS Isolation Kit (Thermo Scientific). miR expression was assessed by quantitative RT-PCR (Applied Biosystems). The expression levels of miR were normalized to miR-16 and calculated using the 2-(Delta Ct) method. A quantitative methylation-specific PCR (MSP) technique was used to analyze miR-203 promoter methylation status. Differences between groups were assessed by Mann-Whitney test (for continuous variables) and chi-squared test (for categorical variables), whereas the correlation was calculated using Spearman's test. The diagnostic performance of miR-203 was defined using receiver operator characteristic (ROC) curves. Results: Serum expression levels of miR-203 were higher in EC patients compared to HC (p = 0.002). Aberrant miR-203 methylation was detected in 11/45 (24.4%) EC patients and in 2/30 (6.6%) HC (p = 0.046). The expression levels of miR-203 were not significantly correlated with promoter methylation status. The area under the curve of miR-203 expression was 0.71 (p = 0.002). Conclusions: The high circulating miR-203 expression levels in EC patients compared to HC confirm the role of this miR as a potential biomarker for diagnosis of EC. Aberrant miR-203 methylation assessed in the peripheral blood does not apparently reflect cancer biology.