Serum Levels of MicroRNA miR-371a-3p: A Sensitive and Specific New Biomarker for Germ Cell Tumours.

BACKGROUND: Clinical management of germ cell tumours (GCTs) relies on monitoring of serum tumour markers. However, the markers α-fetoprotein (AFP), the ß-subunit of human chorionic gonadotropin (bHCG), and lactate dehydrogenase (LDH) are expressed in <60% of GCT cases. OBJECTIVE: To test the utility of the microRNAs (miRNAs) miR-371a-3p, miR-372-3p, miR-373-3p, and miR-367-3p as sensitive and specific GCT serum biomarkers. DESIGN, SETTING, AND PARTICIPANTS: Serum levels of miRNAs were measured in 166 consecutive patients with GCT before and after treatment and in 106 male controls. In the first 50 consecutive patients, all four miRNAs were measured. In the main study, only the most sensitive miRNA was further analysed. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The specificity and sensitivity of the four miRNAs were studied using receiver operating characteristic curves. miRNA sensitivities were compared to those of classical markers. Statistical cross-comparisons of miRNA levels for GCT subgroups and controls were performed at various time points during treatment. RESULTS AND LIMITATIONS: Overall, miR-371a-3p performed best, with 88.7% sensitivity (95% confidence interval [CI] 82.5-93.3%) and 93.4% specificity (95% CI 86.9-97.3%) and an area under the curve of 0.94, outperforming AFP, bHCG, and LDH (combined sensitivity 50%). According to Kernel density estimation, the sensitivity and specificity were 86.3% and 92.5%, respectively. miR-371a-3p levels dropped to normal after completion of treatment. The miRNA levels correlated with treatment failure and relapse. Teratoma did not express miR-371a-3p. CONCLUSIONS: The miRNA miR-371a-3p is a specific and sensitive novel serum GCT biomarker that accurately correlates with disease activity. Validation of this test in a large-scale prospective study is needed. PATIENT SUMMARY: miR-371a-3p is a novel serum marker for germ cell tumours that is expressed by 88.7% of patients and thus is far more sensitive and specific than classical serum markers. It correlates with tumour burden and treatment results. Validation in a large patient cohort is needed.

MicroRNA miR-371a-3p - A Novel Serum Biomarker of Testicular Germ Cell Tumors: Evidence for Specificity from Measurements in Testicular Vein Blood and in Neoplastic Hydrocele Fluid.

BACKGROUND: microRNAs (miRs)-371-3 are suggested to be novel biomarkers of germ cell tumors (GCTs), but their specificity is unresolved. We aimed at clarifying the origin of miR 371a-3p by measuring this miR in peripheral vein blood, and in fluids present in the vicinity of GCTs. METHODS: miR-371a-3p levels were measured by quantitative PCR in 9 tumor surrounding hydroceles and in cubital vein blood (CVB) and testicular vein blood (TVB) of 64 GCT patients, 51 with clinical stage (CS) 1, 13 with CS2-3. Thirty three CS1 cases had also postoperative CVB measurement. TVB miR levels were compared with those of CVB. Associations with clinical factors were analyzed statistically. RESULTS: TVB miR levels were 294-fold, 80-fold and 4.6-fold higher than those in CVB of CS1 patients, CS2-3 patients and controls, respectively. Neoplastic hydrocele fluid comprised of very high miR levels. In CS1, miR levels dropped to normal postoperatively. Statistically, CVB miR levels are significantly associated with tumor size (p = 0.0211) and testis length (p = 0.0493). TVB miR levels are associated with testis length (p = 0.0129). CONCLUSIONS: This study provides evidence for the origin of circulating miR 371a-3p molecules from GCT cells. miR-371a-3p represents a specific serum biomarker for germ cell cancer.

Is relative quantification dispensable for the measurement of microRNAs as serum biomarkers in germ cell tumors?

BACKGROUND: Classical biomarkers α-fetoprotein, ß-human chorionic gonadotropin and lactate dehydrogenase (AFP, bHCG and LDH) are elevated in only 60% of all testicular germ cell tumor (TGCT) patients. microRNAs (miRNAs) are a novel class of useful biomarkers in cancer and miRNAs of the miR-371-3 cluster were proven to be valuable markers for TGCT patients. MATERIALS AND METHODS: We compared the Ct and ΔCt values of miR-371-3 by real time PCR (qPCR) with and without 18S rRNA for normalization. Expression of miR-371a-3p, miR-372 and miR-373-3p was measured in 25 TGCTs, 4 non-TGCTs and 17 age-matched male controls. RESULTS: A highly positive correlation between Ct and ΔCt values was found in all samples. The highest correlation was found for miR-371a-3p (R2: 0.956). CONCLUSION: RESULTS show that qPCR can be used without endogenous control for analyzing miR-371-3 in the serum of patients with testicular cancer and male controls if the technical procedure is performed under controlled conditions.