Increased Nicotinamide Phosphoribosyltransferase and Cystathionine-β-Synthase in Renal Oncocytomas, Renal Urothelial Carcinoma, and Renal Clear Cell Carcinoma

Background: Renal oncocytomas (ROs), and clear cell (RCC) and urothelial carcinomas (UC), are common renal neoplasms. Nicotinamide phosphoribosyltransferase (Nampt) catalyzes the rate-limiting step of NAD(+) synthesis and its expression is increased in several tumors. Nampt concomitantly regulates hydrogen sulfide (H2S)-synthesizing enzyme levels, including cystathionine-beta-synthase (CBS). Materials and Methods: We used tissue microarrays to examine Nampt and the H2S-synthesizing enzyme CBS protein levels in benign kidney, RCC, UC and ROs. Results: Compared to benign kidney, all three neoplasms showed increased Nampt and CBS protein levels, with the levels increasing in RCC at higher Fuhrman grades. Conclusion: H2S is known to ameliorate chronic renal failure but, as yet, no role for H2S in renal neoplasia has been demonstrated. Here, we showed, for the first time, that Nampt, CBS and, likely, H2S likely play a role in malignant and benign neoplastic renal disease.