TTPAL promotes gastric tumorigenesis by directly targeting NNMT to activate PI3K/AKT signaling

Copy number alterations are crucial for gastric cancer (GC) development. In this study, Tocopherol alpha transfer protein-like (TTPAL) was identified to be highly amplified in our primary GC cohort (30/86). Multivariate analysis showed that high TTPAL expression was correlated with the poor prognosis of GC patients. Ectopic expression of TTPAL promoted GC cell proliferation, migration, and invasion in vitro and promoted murine xenograft tumor growth and lung metastasis in vivo. Conversely, silencing of TTPAL exerted significantly opposite effects in vitro. Moreover, RNA-sequencing and co-immunoprecipitation (Co-IP) followed by liquid chromatograph-mass spectrometry (LC-MS) identified that TTPAL exerted oncogenic functions via the interaction of Nicotinamide-N-methyl transferase (NNMT) and activated PI3K/AKT signaling pathway. Collectively, TTPAL plays a pivotal oncogenic role in gastric carcinogenesis through promoting PI3K/AKT pathway via cooperating with NNMT. TTPAL may serve as a prognostic biomarker of patients with GC.