Is measuring serum levels of microRNA miR-371a-3p superior to the classical biomarkers of testicular germ cell tumors?

Abstract

376 Background: There is need for more serum biomarkers of testicular germ cell tumors (GCTs) because the management of GCT is largely based on marker monitoring but only 60% of patients express the classical markers AFP and beta HCG. We measured serum levels of microRNA miR-371a-3p (miR-371) in GCT patients with the aim of establishing a new biomarker. Methods: Serum samples of 130 consecutive patients with GCT (75 seminoma, 55 nonseminoma; 90 clinical stage 1, 40 higher stages) were examined for miR-371a-3p before and after treatment. 105 young males with nonmalignant testicular diseases and 10 patients with non-GCT testis tumors served as controls. Serum levels of miR-371a-3p were measured by quantitative polymerase chain reaction with quantification in relation to miR-20a as internal standard. Measurements were correlated with clinical data, analysis involved descriptive statistical methods. Results: Over 90% of all patients had higher serum levels of miR-371a-3p than controls. After treatment, all elevated levels decreased to the normal range. All metastasized patients had significantly higher mean levels than stage 1 patients, serum levels appear to correlate with tumor bulk. Upon chemotherapy levels decreased with each cycle of therapy. After orchiectomy in stage 1 cases, serum levels dropped by 95% within 24 hours. Nonseminomas had higher mean levels than seminoma. Teratoma does not express miR-371a-3p. The levels remained low during follow-up. Conclusions: Serum levels of microRNA miR-371a-3p appear to comprise of all attributes of a valuable serum biomarker of germ cell tumors. This marker is also expressed in seminoma and it apparently outperforms the classical markers. Evaluation in a large scale multicentric study is warranted.