Presentation Authors: Pia Paffenholz*, Melanie von Brandenstein, Barbara Köditz, Jennifer Thönnissen, Johannes Salem, Tim Nestler, Heike Göbel, Jochen W.U. Fries, Axel Heidenreich, Cologne, Germany
Introduction: Since it is known, that Seminoma can be Epstein-Barr virus positive, the regulation mechanism between the tumor development and the EBV positivity is still unkown. EBV is involved in several different cancers and is the predominant activator of the miR-199a-3p. MiRs are small non coding RNA sequences which regulate the expression of proteins. The miR-199a-3p binds to the 3â€™UTR of Endothelin-1 (ET-1) a vasoconstrictive protein. One of the two ET-1 receptors (ETAR and ETBR), namely the ETBR receptor is in seminoma with non-metastasizing potential downregulated indicating that an imbalance of the ET-1 cycle is present. ET-1 is an important activator for the miR-498 a miR which is necessary for the production of a truncated version of Vimentin, called Vim3. Vim3 is involved in several different processes and is upregulated in tumors with increasing metastasizing potential. This work predominantly focused on the EBV induced signaling and if this signaling process influences the Vim3 expression in seminoma.
Methods: Patient serum and paraffinized tissue samples from seminoma patients and control patients were accessed through our biobank (n=40). The disease group consists of patients with pT1-pT2 diagnosed seminoma with and without metastasis. On paraffinized tissue samples from patients with and without Seminoma as well as a high control (patient with Lymphoma) an IHC staining of the presence of EBV was performed. Furthermore, miR was isolated and miR-199a-3p qRT-PCR was established. Via ELISA the presences of ET-1 and Vim3 was analyzed in patient serum with and without seminoma samples (n=38).
Results: IHC staining shows that 62.5% of our seminoma samples were positive for EBV and 32.5% were negative. No differences between the tumor staging and the metastasising behaviour were detectable. The miR results indicate that the miR-199a-3p was significantly upregulated in all EBV+ samples. Vim3 staining was negative in all EBV+ positive tumors. ELISAs from patient serum samples with and without seminoma indicate that ET-1 and Vim3 was significantly downregulated in seminoma samples.
Conclusions: Here we present for the first time, the correlation between EBV infection and the downregulating mechanism of Vim3. EBV is responsible for the upregulation of miR-199a-3p which binds to the 3â€™UTR of the ET-1 mRNA and resulting in significant downregulation of ET-1. ET-1 is the main inducer of Vim3, which was as well downregulated in EBV+ seminoma. Further studies needed to show whether patients with EBV+ seminoma have a better prognosis, since the Vim3 metastasizing marker is downregulated.