Small RNAseq using tumor-derived extracellular vesicles

RNA modifications play important roles in cellular processes, and their dysregulation has been linked to various diseases, including cancer. As extracellular vesicles (EVs) contain various RNAs, it is assumed that these can be modified. However, the presence of such modified transcripts has not been determined due to the small amount of RNAs in EVs. Herein, we successfully detected 22 RNA modifications in EVs using a proprietary ultra-high performance liquid chromatography tandem mass spectrometry system and identified reduced levels of N6-methyladenosine (m6A) in EVs derived from colon cancer tissues, which correlated with cancer recurrence. Increasing m6A modification levels in colorectal cancer EVs via m6A demethylase Alkbh5 knockout suppressed the tumor-promoting effect of colorectal cancer EVs. Mechanistically, colorectal cancer-derived EVs increased tumor necrotic factor a and interleukin-6 secretion by macrophages via toll-like receptor 8 in an m6A-dependent manner and promoted cancer cell proliferation. RNA-seq analysis showed that 5'-tRF-GlyGCC were enriched in colorectal cancer EVs, and m6A levels on 5'-tRF-GlyGCC were decreased in colorectal cancer EVs compared with those in normal colon EVs. Cancer-derived EVs containing 5'-tRF-GlyGCC significantly promoted tumor growth, and the effect was impeded through macrophage depletion. These data provide evidence that cancer-specific RNA modifications are present in EVs, promoting tumor progression by regulating immune cells. Overall design: To investigate the colon cancer-charachteristic small RNA in EVs, we analyzed EV-RNA from colon cancer-tissue derived EVs (small EVs=6, large EVs=6) and adjacent norrmal colon-tissue derived EVs (small EVs=6, large EVs=6).