Altered Arginine Metabolism Affects Proliferation and Radiosensitivity of Keloids

Keloid is characterised by the reprogramming of cellular metabolism, wherein keloid cells adapt their metabolic pathways to meet the demands for energy and biosynthetic precursors. Investigating the intricate relationship between cellular metabolism and the biological behaviour of keloid holds the potential to yield novel therapeutic strategies for keloid. To elucidate the molecular alterations and potential underlying regulatory mechanisms in keloids, we created comprehensive metabolic profiling at the pathway level by analysing metabolomic, transcriptomic and single-cell RNA-sequencing data from keloids and adjacent skin. Viability assay and clonogenic assay were performed to validate the function of the metabolic pathway(s) in primary keloid fibroblast cells. Integrated analysis revealed an upregulation of arginine and proline metabolism in keloids. According to single-cell RNA-seq data, elevated expression of genes related to arginine and proline metabolism, such as P4HA3, P4HA2, P4HA1, PYCR1, OAT and ASS1, was predominately highly expressed in fibroblast-2. Fibroblast-2 displayed more obvious phenotypes of mesenchymal fibroblast. Critical genes from integrated analysis including P4HA3, P4HA2, P4HA1, PYCR1 and AZIN2, and metabolites including fumaric acid and 2-oxo-5-amino-pentanoic acid showed prognostic relevance with disease-free survival of keloid. Additionally, an In vitro study showed that arginine deprivation therapy (ADT) inhibited and radiosensitised the proliferation of keloid-derived fibroblasts. In conclusion, our thorough multiomics study deepens our understanding of the link between arginine and proline metabolism and keloid proliferation and radiosensitivity. Elevated activity of arginine and proline metabolism in mesenchymal fibroblasts may be a potential therapeutic pathway for keloid.