Description
Genetic susceptibility underlies the pathogenesis of cancer. Through genome-wide  association studies, we and others have previously identified a novel susceptibility  gene, TNFRSF19, which encodes an orphan member of the TNF receptor superfamily,  to be associated with nasopharyngeal carcinoma (NPC) and lung cancer risk. Here, we  show that TNFRSF19 is highly expressed in NPC and is required for cell proliferation  and NPC development. However, unlike most of TNF receptors, TNFRSF19 is not  involved in NF-B activation or associated with TRAF proteins. By affinity  purification, we identified TGF receptor type-I (TRI) as a specific binding partner  for TNFRSF19. TNFRSF19 binds to the kinase domain of TRI in the cytoplasm and  thereby blocks the Smad2/3 association with TRI and subsequent signal transduction.  Ectopic expression of TNFRSF19 in normal epithelial cells confers resistance to the  cell cycle block induced by TGF, whereas knockout of TNFRSF19 in NPC cells  unleashes a potent TGF response characterized by upregulation of Smad2/3  phosphorylation and TGF target gene transcription. Furthermore, elevated  TNFRSF19 expression correlates with reduced TGF activity and poor prognosis in  NPC patients. Our data reveal that gain-of-function of TNFRSF19 in NPC represents  a mechanism by which tumor cells evade the growth-inhibitory action of TGF.