NAD(+) Metabolism Reprogramming Drives SIRT1-Dependent Deacetylation Inducing PD-L1 Nuclear Localization in Cervical Cancer.

Cervical cancer (CC) is a major health threat to women, with immunotherapies targeting the programmed death receptor 1/programmed death ligand 1(PD-1/PD-L1) axis showing promise but encountering resistance in a significant patient population. This resistance has driven a critical quest to uncover the underlying mechanisms. This study uncovers a novel metabolic axis involving the nicotinamide adenine dinucleotide (NAD(+)) salvage pathway enzyme nicotinamide phosphoribosyltransferase (NAMPT) and the deacetylase Sirtuin 1 (SIRT1), which regulates PD-L1 expression and nuclear localization in CC. This axis may be a key factor contributing to the resistance observed in immunotherapy. This study reveals that PD-L1 overexpression in cancers is regulated by both transcriptional and post-transcriptional processes. Acetyl-proteomic analysis pinpoints SIRT1 as a central regulator in the deacetylation of histone H3 at lysines 27, which may influence PD-L1 subcellular distribution. This finding reveals the epigenetic control of immune checkpoint proteins by metabolic pathways, offering a new perspective on the regulation of PD-L1. The identification of the NAMPT/SIRT1 metabolic axis as a critical factor suggests that targeting this axis may enhance therapeutic responses.