Using several xenograft models, it was demonstrated that specific types of selenium-containing molecules, Seleno-L-methionine (SLM) and Se-methyl-selenocysteine (MSC), are effective inhibitors of biomarkers overexpressed in the majority of ccRCC tumors, including HIF-1/2α, miRS-210/-155, Nrf2, and TGF-β. This evidence concerns the gene TGFB1 and nonpapillary renal cell carcinoma.