Pan-cancer tumor-specific antigens and membrane targets from transposable elements

We charted the transcription start sites (TSSs) landscape globally to determine the expressed isoform of each gene and validate the precence of transposable element-derived transcript. Cryptic promoters within transposable elements (TEs) are transcriptionally reactivated in tumors to create novel TE-gene chimeric transcripts, which can produce immunogenic antigens. We performed the most comprehensive screen to date for these TE exaptation events in 33 TCGA tumortypes,675 cancer cell lines, and 11,686 GTEx adult tissue transcriptomes and identified 201,068 TE-exapted candidates with the potential to generate shared tumor-specific TE-chimeric antigens (TS-TEAs). Resultant whole lysate and HLA-pull down mass spectrometry data confirmed that TS-TEAs are presented on cancer cell surfaces. In addition, we highlight the tumor-specific membrane proteins transcribed from TE promoters that can expose novel epitopes on the extracellular surface of cancer cells. Here, we showcase the high pan-cancer prevalence of TS-TEAs and atypical membrane proteins that can be therapeutically exploited through immunotherapy approaches. Overall design: nanoCAGE libraries was generated for variuos cancer cell lines across different cancer types.