MicroRNA miR-371a-3p in serum of patients with germ cell tumours: evaluations for establishing a serum biomarker.

As only 60% of the patients with germ cell tumour (GCT) express the classical markers, new markers as for example microRNAs (miRNAs) are required. One promising candidate is miR-371a-3p, but data are sparse to date. We measured serum levels of miR-371a-3p in GCT patients, in controls, and in cases with other malignancies. We also assessed the expression in other body fluids and we looked to the decline of serum miR-371a-3p levels after treatment. miR-371a-3p levels were measured by quantitative polymerase chain reaction in serum samples of 25 GCT patients, 6 testicular intraepithelial neoplasia (TIN) patients, 20 healthy males and 24 non-testicular malignancies (NTMs). Testicular vein blood (TVB) was examined in five GCT patients and five controls. Five GCT patients had serial daily measurements after orchiectomy. Five seminal plasma samples, three urine specimens and one pleural effusion fluid were processed likewise. GCT patients had significantly higher miR-371a-3p serum levels than controls and NTMs. Serum levels of controls, TINs and NTMs were not significantly different. TVB samples of GCT patients had 65.4-fold higher serum levels than peripheral blood. Malignant pleural effusion fluid had extremely high levels of miR-371a-3p, seminal plasma had strongly elevated levels by comparison with serum levels of controls. In urine of GCT patients, no miR-371a-3p expression was detected. Daily measurements after orchiectomy in stage 1 patients revealed a decline by 95% within 24 h. Serum levels of miR-371a-3p appear to be a promising specific biomarker of GCTs as is suggested by high serum levels in GCT patients, the rapid return of elevated levels to normal range after treatment, the association of serum levels with tumour bulk, the non-expression in NTMs and the much higher levels of miR-371a-3p in TVB. This potential marker deserves further exploration in a large-scale clinical study.

MicroRNAs miR-371-3 in serum as diagnostic tools in the management of testicular germ cell tumours.

BACKGROUND: miRNAs are small noncoding RNA molecules that can be released into body fluids. Germ cell tumours (GCTs) overexpress miRNAs of the miR-371-3 cluster. Thus, serum levels of these miRNAs may correlate with tumour load. METHODS: miRNAs of the miR-371-3 cluster were quantified in cubital vein blood samples of 20 GCT patients with clinical stage 1, and of 4 patients with advanced stages before and after treatment. In six patients testicular vein blood (TVB) was examined additionally. Seventeen healthy males served as controls. Likewise, expression of miRNAs in 15 matching tumour specimens was measured. RESULTS: In all patients, serum levels of miRNAs 371-3 were much higher than in controls. In stage 1, levels decreased postoperatively 336.7-fold, 7.4-fold, and 7.7-fold for miRNAs 371a-3p, 372, and 373-3p, respectively (P<0.01). Also, in those cases with advanced disease levels dropped to the normal range after completion of treatment. miR-371-3 levels in TVB exceeded those in peripheral blood in all cases. Expression of miR-371a-3p was also documented in tumour tissue. However, no correlation was found regarding the extent of miRNA expression in tissue and the values measured in matching serum. CONCLUSION: Thus, miR-371a-3p serum level appears to be a useful biomarker in GCTs.