Proteomics\nAnalysis of Renal Cell Line Caki‑2\nwith AFMID Overexpression and Potential Biomarker Discovery in Urine

Aromatic caninurine formamase (AFMID) is an enzyme involved\nin\nthe tryptophan pathway, metabolizing N-formylkynurenine to kynurenine.\nAFMID had been found significantly downregulated in clear cell renal\ncell carcinoma (ccRCC) in both tissue and urine samples. Although\nccRCC is characterized by a typical Warburg-like phenotype, mitochondrial\ndysfunction, and elevated fat deposition, it is unknown whether AFMID\nplays a role in tumorigenesis and the development of ccRCC. In the\npresent study, AFMID overexpression had inhibitory effects for ccRCC\ncells, decreasing the rate of cell proliferation. Quantitative proteomics\nshowed that AFMID overexpression altered cellular signaling pathways\ninvolved in cell growth and cellular metabolism pathways, including\nlipid metabolism and inositol phosphate metabolism. Further urine\nproteomic analysis indicated that cellular function dysfunction with\nAFMID overexpression could be reflected in the urine. The activity\nof predicted upregulators DDX58, TREX1, TGFB1, SMARCA4, and TNF in\nccRCC cells and urine showed opposing change trends. Potential urinary\nbiomarkers were tentatively discovered and further validated using\nan independent cohort. The protein panel of APOC3, UMOD, and CILP\nachieved an AUC value of 0.862 for the training cohort and 0.883 for\nthe validation cohort. The present study is of significance in terms\nof highlighting various aspects of pathway changes associated with\nAFMID enzymes, discovering potential specific biomarkers for potential\npatient diagnosis, and therapeutic targeting.