The N6-methyladenosine reader protein YTHDC2 promotes gastric cancer progression via enhancing YAP mRNA translation.

N6-methyladenosine (mA) modification is the most prevalent internal modification in eukaryotic mRNA. YTH domain containing 2 (YTHDC2), a mA binding protein, has recently been identified as a key player in human cancer. However, its contribution to gastric cancer (GC) remains unknown. Herein, we found that YTHDC2 was significantly upregulated in human GC tissues and associated with poor prognosis. CRISPR-Cas9 mediated YTHDC2 knockout notably inhibited GC cell viability, proliferation and invasion. Transcriptome analysis coupled with mechanism experiments revealed that yes-associated protein (YAP), the well-known oncogene, is the target of YTHDC2 in GC cells. Specifically, YTHDC2 recognized mA-modified YAP mRNA at 5`-UTR, resulting in enhancing the translation efficiency of YAP, without affecting its mRNA level. In turn, YAP/TEAD directly targeted -843∼-831 region on the promoter of YTHDC2 and activated the transcription of YTHDC2, thus forming a positive regulatory loop. Further, using the xenograft tumor model, we found that knockout of YTHDC2 markedly reduced tumor size and lung metastasis nodules in vivo. And high YTHDC2 was strongly positively correlated with high YAP in clinical GC tissues. Collectively, our data demonstrate that YTHDC2 is a novel oncogene in GC, which provides the theoretical basis for the strategy of targeting YTHDC2 for GC patients.