Analysis of MicroRNA-371-373 supports that a subset of spermatocytic tumors demonstrates biologic features similar to those of GCNIS-derived germ cell tumors.

Spermatocytic tumors are rare testicular tumors occurring predominantly in older men. Most show a classical tripartite morphology (different from seminoma) and are benign. However, well-documented cases of malignant spermatocytic tumors exist. Our previous work showed that a subset of spermatocytic tumors exhibiting TP53 mutations, DNA methylation profiles closer to seminomas, and/or gains in chromosome 12p exhibited aggressive characteristics, including sarcomatoid transformation and metastatic dissemination. The microRNA-371-373 cluster is a promising biomarker which is upregulated in non-teratoma germ cell tumors with malignant behavior. In this work we analyze microRNAs-371-373 b y quantitative real-time polymerase chain reaction in 18 spermatocytic tumors representative of the whole clinical spectrum, including 6 with aggressive features (sarcomatoid transformation, metastases, or gains in chromosome 12p). The levels of microRNAs-371-373 were significantly higher in non-teratoma germ cell tumors compared to spermatocytic tumors, overall (p < 0.0001). Importantly, levels of microRNA-371-373 were higher in spermatocytic tumors with aggressive features compared to non-aggressive neoplasms. The highest levels were observed in one tumor showing isochromosome 12p. These results further support our previous findings that a subset of spermatocytic tumors are intermediate between so-called type II and type III germ cell tumors and that embryonic microRNAs play a role in aggressive behavior in spermatocytic tumors. Accordingly, this subset of tumors may behave aggressively and require close follow up. In the future, this opens an opportunity for microRNA testing in serum of spermatocytic tumor patients for risk stratification purposes.