SIRT1 and hepatocellular carcinoma: Also, SIRT1 negatively regulates GH-induced IGF-1 mRNA production, which was confirmed in a human hepatocellular carcinoma cell line (HepG2) and rat primary hepatocytes, with the use of SIRT1 inhibitors (sirtinol and nicotinamide) and stimulators (resveratrol and NAD) [15].