Potent Inhibition of Nicotinamide N-Methyltransferase by Alkene-Linked Bisubstrate Mimics Bearing Electron Deficient Aromatics

Abstract

Nicotinamide N -methyltransferase (NNMT) methylates nicotinamide (vitamin B3) to generate 1-methylnicotinamide (MNA). NNMT overexpression has been linked to a variety of diseases, most prominently human cancers, indicating its potential as a therapeutic target. The development of small-molecule NNMT inhibitors has gained interest in recent years, with the most potent inhibitors sharing structural features based on elements of the nicotinamide substrate and the S -adenosyl- l -methionine (SAM) cofactor. We here report the development of new bisubstrate inhibitors that include electron-deficient aromatic groups to mimic the nicotinamide moiety. In addition, a trans -alkene linker was found to be optimal for connecting the substrate and cofactor mimics in these inhibitors. The most potent NNMT inhibitor identified exhibits an IC 50 value of 3.7 nM, placing it among the most active NNMT inhibitors reported to date. Complementary analytical techniques, modeling studies, and cell-based assays provide insights into the binding mode, affinity, and selectivity of these inhibitors.

Methyl Donors Reduce Cell Proliferation by Diminishing Erk-Signaling and NFkB Levels, While Increasing E-Cadherin Expression in Panc-1 Cell Line

“…They refer to studies where silenced NNMT has resulted in decreased migration, invasion, proliferation, and increased chemosensitivity [ 50 ], and also that NNMT expression is enhanced in cancer stem cells [ 51 ]. The NNMT enzyme takes a methyl group from S-adenosyl-L-methionine (SAM) and adds it to nicotinamide (NA), generating methyl-nicotinamid (MNA) and S-adenosyl-L-homocysteine as a result [ 52 ]. It is believed that it would decrease the methylation capacity of the methionine cycle towards the DNA/histone methylation path, causing aberrant methylation, which could lead to cancer progression in the case of the overexpression of NNMT.…”

Nicotinamide N-Methyltransferase in Head and Neck Tumors: A Comprehensive Review

“…However, further studies on larger cohorts of patients are needed to confirm these findings and to explore the biological role of NNMT in HNT. Moreover, this enzyme could be a promising target for cancer therapy, which can be studied in more detail thanks to the development of specific NNMT inhibitors which have shown promising results in preclinical studies [ 46 , 47 , 48 , 49 , 50 , 51 ].…”

Nicotinamide N-Methyltransferase: An Emerging Protagonist in Cancer Macro(r)evolution

“…At the time of writing, the specificity of these inhibitors for NNMT over other methyltransferases has yet to be published. Our most recent inhibitor, (S)-2-amino-4((((2R,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-3,4-dihydroxytetrahydrofuran-2-yl)methyl)((E)-3-(4-cyanophenyl) allyl)-amino)butanoic acid (compound 17u), replaces the nicotinamide mimic common in current bisubstrate inhibitors with an electron-deficient para-cyano aromatic group coupled with a trans-alkene linker, resulting in an IC 50 of 1.7 nM [222]. Inhibitor selectivity studies revealed that compound 17u has 3000-fold higher activity towards NNMT than PNMT.…”