The potential mechanisms of statins in hepatocellular carcinoma prevention

ROMERO-CAÍMI, G; DEZA, Z; KLEIMAN DE PISAREV, D; CALVO G; RIDRUEJO, E; SAENZ D; ALVAREZ, L

Punta Cana

Congreso; XXV Congreso ALEH 2018.; 2018

Asociación Latinoamericana para el estudio del hígado, ALEH

The potential mechanisms of statins in hepatocellular carcinomaprevention  Ridruejo, Ezequiel 1,2, Deza, Zahira A2,  Romero-Caími, Giselle 2, Daniel Saenz3,Gustavo Calvo3, Kleiman de Pisarev, Diana2  and Laura Alvarez 2  1Hepatology Section, Department ofMedicine. Centrode Educación Médica e Investigaciones Clínicas ?Norberto Quirno? (CEMIC). Ciudad Autónoma de Buenos Aires. Argentina. 2Laboratoryof Biological Effects of Environmental Pollutants, Department of HumanBiochemistry, Faculty of Medicine, University of Buenos Aires. Ciudad Autónomade Buenos Aires. Argentina.3Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), Hospitalde Clínicas ?José de San Martín?, UBA-CONICET. CiudadAutónoma de Buenos Aires. Argentina.Background: Hepatocellular carcinoma (HCC) is the most frequentprimary hepatic tumor and its incidence is increasing. HCC prognosis is relatedto early diagnosis. Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzymeA reductase (HMG-CoAR), have been used in treatment of different tumors. Itsprecise anti-tumoral mechanism of action has not been established. We hadpreviously demonstrated in vivo that hexachlorobenzene (HCB), a dioxin-liketoxic, acts as an endocrine disruptor who is capable of stimulating cellproliferation and developing preneoplastic foci in the liver, increasingHMG-CoAR mRNA, transforming growth factor-β1 (TGF-β1) levels and thyroidhormone (TH) dysregulation.  In addition,increasing evidence indicates that alterations in glutathione levels  can contribute to tumor growth andprogression. Our aim was to evaluate TGF-β1, T3 and glutathione levels involvement inhepatocarcinogenesis and the potential mechanisms of statins in preventing it.Methods: We used an initiation-promotion model inHep-G2 cells using HCB (5 μM) to develop HCC. We evaluated the effects of different doses ofatorvastatin (AT, 10, 20 y 30µM) and simvastatin (SM, 5, 10, 20µM) on proliferating cell nuclear antigen (PCNA),pSMAD and pERK (WesternBlot), TGF-β1  and deiodinase I (DI) mRNA (RT-PCR), and  TH (RIA) levels. We evaluated the anti-proliferative effect ofdifferent T3 doses (10-9, 10-7, 10-5M) for 24 h and subsequent HCB 5 μM + T3  at the same doses for 24 h. We also analyzedthe effects of HCB 0,005 μM and 5 μM on hydrogen sulfide (H2S)generation using L-cysteine sustratum at 5 mM doses for 24 h.Results: The induced increasein PCNA levels was reduced by 71% with AT 20 μM, and by 100% with AT 30 μM. It was alsoreduced by 80% with SM 10 μM and by 100% with SM 20 μM. Pre-incubation with AT 30 μM and SM 20 μM prevented anincrease in TGF-β1 andSMADp  as well as the decrease in DI mRNAlevels. Pre-incubation with an TGF-β1 inhibitor (SB431542, 10 μM) prevented an increase in PCNA, SMADp, pERKand a decrease in DI mRNA levels. Hep-G2 cells were pre-treated with differentT3 doses and T3 at 10-5 M prevented theproliferative effect of HCB on pERK and PCNA levels.  When HepG2 cellswere preincubated with L-cysteine and subsequently treated with HCB (5μM), alower production of  H2S (38%)was observed. This experiment strongly suggests the reduction of the generationof glutathione and possible alteration of the redox state generated in thehepatocarcinogenic process.Conclusion: TGF-β1, T3 andalteration of the redox state may be partly responsible for the protectiveeffect of statins on cell proliferation generated by HCB, and may be moleculartargets in the treatment of HCC. Keywords: HCC,Statins, TGF- β1,Thyroid hormones, ROS and H2S .