Nicotinamide Mononucleotide Versus Nicotinamide Riboside in The Protective Effects of Cisplatin-induced DNA Damage in HeLa Cells

Abstract

Abstract Background Previous studies have shown that the nicotinamide adenine dinucleotide (NAD+) precursors, nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), protected against endogenously or exogenously induced DNA damage, however, whether the two compounds have the same or different efficacy against DNA damage is not clear. In the current study, we systematically compared the effects of NMN and NR on cisplatin-induced DNA damage in HeLa cells. Methods The viability of cisplatin treated HeLa cells with NMN or NR were tested by Trypan blue staining. NMN and NR were added in cells before or after exposed to cisplatin, respectively. Briefly, HeLa cells were pretreated with series doses of NMN or NR (0、0.625、1.25、2.5、5 and 10 mM) for 12 h, and then challenged with 10 µM of cisplatin for the following 12 h; or, HeLa cells were treated by 10 µM of cispaltin for 12 h, and then cultured in medium with 10mM NMN or NR, the cells were harvested at 0, 8, 16, 24 and 32 h later. The DNA damage were assessed by immunofluorescent against phosphor-H2AX (γH2AX) and alkaline comet assay. The intracellular nicotinamide adenine dinucleotide (NAD+) and reactive oxygen species (ROS) were determined by according kit. Results Both NMN and NR could rescued cisplatin-induced cell death in a dose-dependent manner comparably. NMN and NR pretreatment decreased γH2AX levels and shortened comet tail length in a dose-dependent manner, while NR pretreatment exhibiting stronger protective effects than NMN. Although the post-cisplatin administration of NMN and NR also exhibited a protective effect against DNA damage, there were no significant differences between the two compounds. In addition, both NMN and NR can reverse the cisplatin-induced decrease of NAD+ and the generation of ROS, also with no significant difference between them. Conclusion NR is more effective than NMN in maintaining DNA integrity in cisplatin-treated cells.