Paox, also known as Polyamine oxidase (N1-acetylpolyamine oxidase), is a key enzyme in the polyamine catabolism pathway. Polyamines are ubiquitous compounds, and their metabolic dysregulation is linked to various pathologies. Paox generates hydrogen peroxide during polyamine catabolism, which is involved in processes like extracellular matrix (ECM) degradation in skin aging by increasing matrix metalloproteinase-1 (MMP-1) levels [1].

In fibroblasts, the expression of Paox increases MMP-1 secretion and type Ι collagen degradation, as well as the production of reactive oxygen species (ROS). It also activates signaling pathways related to activator protein-1 (AP-1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), important transcription factors for MMP-1 transactivation [1]. In breast cancer cells, 17β-estradiol treatment reduces Paox mRNA and protein levels through estrogen receptor 2 (ESR2), suggesting that estrogen deficiency may upregulate Paox expression [3]. Additionally, in non-small-cell lung cancer patients, the polymorphism of the Paox rs1046175 locus affects the diagnostic value of plasma Pro-SFTPB and DAS [2].

In conclusion, Paox plays a significant role in polyamine catabolism and is associated with multiple disease-related processes such as skin aging, breast cancer, and non-small-cell lung cancer. Research on Paox provides insights into the underlying mechanisms of these diseases, potentially offering new targets for treatment and diagnosis.