MicroRNA 182, 183, 200a, and 200b exhibit strong correlations but no involvement in PTEN protein regulation in uterine endometrial carcinoma.

Objective: In this study, we focused on five microRNAs (miRNAs) that have been reported to regulate phosphatase and tensin homolog deleted on chromosome 10 (PTEN) gene expression, namely miR-182, miR-183, miR-200a, miR-200b, and miR-205, and examined their relationships with PTEN protein expression in endometrial cancer tissues.

Methods: By utilizing paraffin-embedded blocks of normal endometrium (NE) and endometrial carcinoma (EC) tissue (40 cases each), we measured the expression of miRNAs by real-time PCR. Conversely, we examined PTEN protein expression by immunohistochemistry and computer-assisted image analysis.

Results: The expression of all five miRNAs was significantly higher in the EC group than in the NE group (all P ≤ 0.0001). There was no inverse correlation between PTEN positivity in glandular and/or stromal areas and the expression of the five miRNAs in both groups. Conversely, miR-182, miR-183, miR-200a, and miR-200b displayed similar expression patterns in the EC group, whereas miR-205 displayed moderate correlations with the other four miRNAs.

Conclusion: Using endometrial cancer tissues, we found for the first time that miR-182, miR-183, miR-200a, and miR-200b were strongly correlated with each other, whereas miR-205 was not strongly correlated with the other four miRNAs. In addition, the five miRNAs examined in this study only had weak effects on PTEN protein expression based on the lack of clear inverse correlations.