Graded expression of microRNA-371a-3p in tumor tissues, contralateral testes, and in serum of patients with testicular germ cell tumor.

Background: Serum levels of microRNA-371a-3p represent a specific tumor marker of testicular germ cell tumors (GCTs) but the origin of circulating miR-371a-3p is not finally resolved. The correlation between miR-levels in tissue and serum is unclear. Results: MiR-levels in GCT tissue are 399-fold higher than in contralateral testicular tissue and 5843-fold higher than in non-testicular tissue. MiR tissue levels correlate with corresponding serum levels (r ² = 0.181). ISH detected miR-371a-3p intracellularly in GCT cells except teratoma. A low expression was also detected in normal testicular germ cells. Conclusions: Circulating miR-371a-3p is specifically derived from GCT tissue. The miR is present in GCT cells except teratoma. A low expression is also found in normal testicular tissue but not in non-testicular tissue. MiR-371a-3p levels in tissue and serum correlate significantly. This study underscores the usefulness of serum miR-371a-3p as tumor marker of GCT. Patients and methods: Expression levels of miR-371a-3p were concurrently measured in tissues of GCT, contralateral testes ( n = 38), and in serum ( n = 36) with real time PCR. For control, 5 healthy testicles and 4 non-testicular tissue samples were examined. MiR-levels were compared using descriptive statistical methods. We also performed in situ hybridization (ISH) of GCT tissue with a probe specific for miR-371a-3p.
Competing Interests: CONFLICTS OF INTEREST Gazanfer Belge and Klaus-Peter Dieckmann each possess 9.7% ownership shares of miRdetect GmbH, Bremen, a start-up company aiming to develop a commercially available test for measuring microRNAs in serum. MiRdetect holds a patent for the measurement of miRNA in body fluids at the limit of detection. All other authors declare no competing interests towards this report. A further patent for the use of miR-371a-3p as a marker for GCNis was filed by miRdetect/University of Bremen on November, 2nd 2016. Arlo Radtke is an employee of miRdetect GmbH, Bremen since January 2019.
(Copyright: © 2020 Belge et al.)