OGT regulated O-GlcNAcylation promotes papillary thyroid cancer malignancy via activating YAP.

The incidence of thyroid cancer is growing rapidly during the past decades worldwide. Although most thyroid tumors are curable, some patients diagnosed with distant metastases are associated with poor prognosis. The molecular mechanisms underlying these cases are still largely unknown. Here we found that the upregulated O-Linked N-Acetylglucosamine Transferase (OGT) expression and O-GlcNAcylation (O-GlcNAc) modification in papillary thyroid cancer (PTC) were essential in tumor growth and metastasis. Mass spectrometry analysis showed that YAP was the effector protein modified by OGT. In details, YAP Ser109 O-GlcNAcylation promoted the malignant phenotypes in PTC cells by inducing YAP Ser127 dephosphorylation and activation. Our work clearly showed the critical role of OGT and YAP played in PTC tumors and made it possible for us to seek the clinical potential of manipulating OGT/YAP activity in PTC targeted therapies. These findings also confirmed OGT worked in collaboration with classical Hippo pathway kinases as an upstream regulator of YAP in PTC tumors.