NNMT and cancer: We observed that many metabolism-related genes were differentially expressed in ccRCC, such as NNMT, lysyl oxidase, transglutaminase 2, heme oxygenase 1, argininosuccinate synthetase, alcohol dehydrogenase 6, and phosphoenolpyruvate carboxykinase 1, indicating that the ccRCC cells might lose their normal functions as the kidney cells, and the metabolism-related genes might play a role in cancer progression.