Potential statins molecular targets in hepatocarcinogenesis prevention

RIDRUEJO E; ROMERO CAIMI G; KLEIMAN DE PISAREV D; ALVAREZ L

Congreso; American Association for the Study of Liver Diseases; 2016

Hepatocellular carcinoma (HCC) represents 90% of liver tumors and it is a global health problem. Statins, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HMG-CoAR), have pleiotropic effects and have been used in the treatment of different tumors. Statins reduce the incidence on various tumors, have anti-tumoral activity through its anti-apoptotic effect and its capacity of inhibiting tumoral invasion and metastasis development. These anti-tumoral activity may be mediated by changes in transforming growth factor-β1 (TGF-β1), epidermal growth factor (EGF) and thyroid hormones (TH) regulation. However, its precise anti-tumoral mechanism of action has not been established. Aim: The aim of our study is to establish the statins mechanism of action and the key molecules involved in an HCC in vitro and in vivo model. Materials and methods: We used an initiation-promotion model in rats and Hep-G2 cells using diethylnitrosamine (DEN, 100 mg/kg bw) and hexachlorobenzene (HCB, 100 mg/kg bw) to develop HCC. In vivo we evaluate: 1- proliferating cell nuclear antigen (PCNA) levels in focal and non focal areas, Western Blot; 2- HMG-CoAR and cholesterol levels in total liver, Kit, RT-PCR; 3- total and phosphorylated Src levels, Western Blot; 4- TGF-β1 levels; 5- TH and deiodinase I and III mRNA levels. In vitro we evaluated the effects of different doses of atorvastatin (AT, 10, 20 y 30µM) and simvastatin (SM, 5, 10, 20µM) on prevention of HCB induced proliferative changes in Hep-G2 cells. In vitro we evaluated: 1- PCNA levels; 2-TGF-β1 mRNA levels; 3- total and phosphorylated c-Src levels, Western Blot; 4- HMG-CoA levels. Results: in vivo, in focal zones DEN+HCB vs. DEN showed elevation in PCNA (60%, p≤0,001), in HMG-CoAR (31%, p≤0,01), in cholesterol (28%, p≤0,05), in TGF-β1 (35%, p≤0,01), and in phosphorylated Src (39%, p≤0,01) levels. DI levels were reduced 41% (p≤0,01) and DIII increased 30% (p≤0,01). Tisular T4 increased 38% (p≤0,01) and tisular T3 reduced 37% (p≤0,01). In vitro, HMG-CoAR mRNA levels were reduced 29% and 38% with AT (20 y 30 mM), and 20% and 31% with SM (10 y 20 µM). Increased in PCNA, TGF-β1, and phosphorylated c-Src, and decreased in DI levels generated by HCB treatment (5uM, 24 hs.) were antagonized by maximun doses of AT (52, 32, 41, 42 %) and SM (58, 36, 40, 39 %), respectively of its maximum effect. They returned to control values. Pre-treatment with an specific TGF- β1 inhibitor (SB431542, 3 hours at 10 uM) prevented the HCB effect on PCNA, TGF-β1, Src and DI. Conclusion: Statins (AT and SM) can revert HCB induced proliferative effects on Hep-G2 cells. TGF-β1, c-Src and TH may be the statins molecular targets in hepatocarcinogenesis.