NAD+ Kinase as a Therapeutic Target in Cancer

NAD⁺ kinase (NADK) catalyzes the phosphorylation of nicotinamide adenine dinucleotide (NAD⁺) to nicotinamide adenine dinucleotide phosphate (NADP⁺) using ATP as the phosphate donor. NADP⁺ is then reduced to NADPH by dehydrogenases, in particular glucose-6-phosphate dehydrogenase and the malic enzymes. NADPH functions as an important cofactor in a variety of metabolic and biosynthetic pathways. The demand for NADPH is particularly high in proliferating Cancer cells, where it acts as a cofactor for the synthesis of nucleotides, proteins, and fatty acids. Moreover, NADPH is essential for the neutralization of the dangerously high levels of Reactive Oxygen Species (ROS) generated by increased metabolic activity. Given its key role in metabolism and regulation of ROS, it is not surprising that several recent studies, including in vitro and in vivo assays of tumor growth and querying of patient samples, have identified NADK as a potential therapeutic target for the treatment of Cancer. In this review, we will discuss the experimental evidence justifying further exploration of NADK as a clinically relevant drug target and describe our studies with a lead compound, thionicotinamide, an NADK inhibitor prodrug. Clin Cancer Res; 22(21); 5189-95. ©2016 AACR.