Abstract

Host and Viral Small RNA and microRNA Profiling in Tumor Tissue and Circulation of Patients with Epstein-Barr Virus Driven Nasopharyngeal Carcinoma

Jaap Middeldorp, Professor, Dept. of Pathology, VU University Medical Center Amsterdam

Epstein-Barr virus (EBV) is linked to undifferentiated nasopharyngeal carcinoma (NPC). We analyse whether host and viral circulating miRNA fingerprints reflect tumor burden and behaviour. Materials & methods: MicroRNA was analysed for frozen NPC biopsies, tonsils compared to whole serum (NPC, healthy controls and non-NPC patients). Selected NPC sera were fractionated into extracellular vesicle and protein fractions. Deep RNA sequencing (RNAseq) was done for NPC cell lines, exosomes and selected sera. EBV DNA load was measured as well. Viral miRNA (mirBART6, 7, 9, 10, 13, 17, mirBHRF1-1), host miRNA (miR16, 21, 155, 223) and small RNAs (EBER1 and vaultRNA) were detected by stemloop RT-PCR. Results: Viral miRNAs were detected in tissue and serum of NPC patients, increasing with TNM stage despite absence of EBV DNA in some. EBER1 RNA was absent in virtually all NPC sera, despite high levels in NPC tissues. Defined viral miRNAs were detectable in NPC sera, but almost absent in controls. Host miR155 was elevated in NPC sera compared to controls. Fractionation from NPC sera revealed miR155 and vaultRNA to be enriched in extracellular vesicles, whereas viral miRNAs were randomly distributed. Detailed RNAseq analysis is in progress. Conclusion: Defined cellular and viral miRNA profiles in EBV-related NPC represent novel biomarkers. EBER1 RNA is not present in NPC sera, likely due to degradation upon release from NPC tumor cells.