Plasma miR-17-5p, miR-20a and miR-22 are down-regulated in women with endometriosis

Abstract

Study question: Can plasma microRNAs be used as a non-invasive diagnostic test for the detection of endometriosis?

Summary answer: Plasma miR-17-5p, miR-20a and miR-22 are down-regulated in women with endometriosis compared with those without endometriosis in mainland China.

What is known already: There is currently a pressing need to develop a non-invasive diagnostic test for endometriosis. Altered circulating microRNA profiles have already been linked to various disease states.

Study design, size, and duration: This was a prospective laboratory study in a tertiary-referral university hospital in Beijing, PR China, between January 2012 and May 2012. Twenty-three women with histologically proven endometriosis and 23 endometriosis-free controls were enrolled in this study.

Participants/materials, setting, and methods: Laparoscopic inspection of the abdominopelvic cavity was performed for each patient, and peripheral blood samples were collected before laparoscopy. Microarray-based microRNA expression profiling was used to identify differentially expressed microRNAs in plasma samples between women with and without endometriosis, and quantification of selected microRNAs was performed using quantitative RT-PCR.

Main results and the role of chance: Twenty-seven microRNAs were differentially expressed between women with and without endometriosis, of which six microRNAs (miR-15b-5p, miR-17-5p, miR-20a, miR-21, miR-22 and miR-26a) were selected for validation. MiR-17-5p, miR-20a and miR-22 were significantly down-regulated in women with endometriosis compared with controls (P = 0.011, 0.0020 and 0.0002, respectively), yielding an area under the receiver operator characteristics curve of 0.74 [95% confidence interval (CI): 0.58-0.90], 0.79 (95% CI: 0.65-0.93) and 0.85 (95% CI: 0.71-0.98) in discriminating endometriosis from controls, respectively.

Limitations and reasons for caution: Our sample size was small and all cases were rAFS stage III-IV, which may limit generalization of plasma microRNAs for early diagnosis of endometriosis. Moreover, only six microRNAs were selected for validation.

Wider implications of the findings: Plasma microRNAs provide a promising opportunity for detection of endometriosis.

Figure 1

Heat map showing 27 differentially expressed (fold change > 2) microRNAs from plasma samples of women with endometriosis (n = 3) and controls having uterine leiomyoma but free of endometriosis (n = 3). Each row represents one microRNA, and each column represents a plasma sample. The legend on the right indicates the microRNA represented in the corresponding row. The relative microRNA expression is depicted according to the color scale. Red indicates up-regulation; green indicates down-regulation. The numbers with E indicate endometriosis; numbers with C indicate controls.

Figure 2

Validation of microRNA expression by qRT–PCR analysis in plasma samples from women with (n = 20) and without endometriosis (n = 20). MicroRNA expression data are presented as fold change relative to the women without endometriosis group (control plasma = 1). Data are represented by scatter plots. The line represents the median value. The P-values were calculated by the Mann–Whitney U-test. Red indicates women with endometriosis and blue indicates women that are endometriosis-free (a and b). In c, red indicates women with endometriosis, green indicates endometriosis-free women without leiomyoma and yellow indicates women with leiomyoma.

Figure 3

ROC curve analysis using plasma microRNAs for discriminating endometriosis. ROC curve analyses revealed that the plasma levels of miR-17-5p, miR-20a and miR-22 were useful biomarkers for differentiating women with and without endometriosis, with AUC values of 0.74 (95% CI: 0.58–0.90), 0.79 (95% CI: 0.65–0.93) and 0.85 (95% CI: 0.71–0.98), respectively. When the three microRNAs were combined by multiplication, the AUC values for differentiating women with and without endometriosis were 0.79 (95% CI: 0.65–0.93), 0.87 (95% CI: 0.74–0.99), 0.88 (95% CI: 0.76–1.00) and 0.90 (95% CI: 0.80–1.00), respectively.