NNMT and hepatocellular carcinoma: Consequently, we postulated a potential association between 1-MNAM and HCC development, suggesting that the declining trend in 1-MNAM levels might signal pre-cancer progression.1-MNAM, primarily synthesized in the liver by Nicotinamide N-methyltransferase (NNMT), is naturally occurring in human plasma and exhibits diverse biological activities, notably anti-inflammatory and antithrombotic effects (Chlopicki et al. 2007; Jakubowski et al. 2016).