910 Overexpression of miR-155–5p can upregulate antigen processing and presentation pathway via targeting tapasin

Background Dysregulation of major histocompatibility complex (MHC) class I antigen processing and presentation machinery (APM) components in the tumor as one main molecular mechanism immune escape leading to deactivation T cell surveillance could be due post-transcriptional regulation via immune-modulatory microRNAs (miRNA). It is now well established from a variety studies that several miRNAs effectively modulate expression some MHC APM tumors. Tapasin an important molecule involved association with transporter associated (TAP) peptide loading. Since so far no detailed investigation posttranscriptional tapasin exists, aim this study identify functionally characterize targeting melanoma. Methods Using miRNA trapping by RNA vitro affinity purification (miTRAP) silico small sequencing, will identified, which bind 3’untranslated region (3’ UTR) tapasin. Dual-luciferase assays performed determine miRNA. In analysis was predict effect on survival melanoma patients correlation RT-qPCR, Western blot, flow cytometry, other functional were after transfecting mimics three lines. Results combination strategy miTRAP seq we identified miR-155-5p 3’UTR tapasin, further confirmed dual-luciferase reporter assay. Transfection demonstrated upregulate protein level, accompanied upregulation (HLA-ABC) surface expression. Simultaneously, different types cancer, including melanoma, significantly positively correlated patient‘s HLA-A protein. Conclusions Our data revealed for first time positive role provide insights into miR-155-5p-mediated induction HLA-ABC This might lead better response, avoidance escape, improvement patients‘ thus potential therapeutic target. Acknowledgements The work supported grant DKH (BS).