The potential mechanisms of statins in hepatocellular carcinoma prevention

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

Punta Cana

Congreso; XXV Congreso ALEH 2018.; 2018

Asociación Latinoamericana para el estudio del hígado, ALEH

Background: Hepatocellular carcinoma (HCC) is the most frequent primary hepatic tumor and its incidence is increasing. HCC prognosis is related to early diagnosis. Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoAR), have been used in treatment of different tumors. Its precise anti-tumoral mechanism of action has not been established. We had previously demonstrated in vivo that hexachlorobenzene (HCB), a dioxin-like toxic, acts as an endocrine disruptor who is capable of stimulating cell proliferation and developing preneoplastic foci in the liver, increasing HMG-CoAR mRNA, transforming growth factor-â1 (TGF-â1) levels and thyroid hormone (TH) dysregulation. In addition, increasing evidence indicates that alterations in glutathione levels can contribute to tumor growth and progression. Our aim was to evaluate TGF-â1, T3 and glutathione levels involvement in hepatocarcinogenesis and the potential mechanisms of statins in preventing it.Methods: We used Hep-G2 cells treated with HCB (5 ìM) to develop HCC. We evaluated the effects of different doses of atorvastatin (AT, 10, 20 y 30µM) and simvastatin (SM, 5, 10, 20µM) on proliferating cell nuclear antigen (PCNA), pSMAD and pERK (Western Blot), TGF-â1 and deiodinase I (DI) mRNA (RT-PCR), and TH (RIA) levels. We evaluated the anti-proliferative effect of different T3 doses (10-9, 10-7, 10-5 M) for 24 h and subsequent HCB 5 ìM + T3 at the same doses for 24 h. We also analyzed the effects of HCB 0,005 ìM and 5 ìM on hydrogen sulfide (H2S) generation using L-cysteine sustratum at 5 mM doses for 24 h.Results: The induced increase in PCNA levels was reduced by 71% with AT 20 ìM, and by 100% with AT 30 ìM. It was also reduced by 80% with SM 10 ìM and by 100% with SM 20 ìM. Pre-incubation with AT 30 ìM and SM 20 ìM prevented an increase in TGF-â1 and SMADp as well as the decrease in DI mRNA levels. Pre-incubation with an TGF-â1 inhibitor (SB431542, 10 ìM) prevented an increase in PCNA, SMADp, pERK and a decrease in DI mRNA levels. Hep-G2 cells were pre-treated with different T3 doses and T3 at 10-5 M prevented the proliferative effect of HCB on pERK and PCNA levels. When HepG2 cells were preincubated with L-cysteine and subsequently treated with HCB (5ìM), a lower production of H2S (38%) was observed. This experiment strongly suggests the reduction of the generation of glutathione and possible alteration of the redox state generated in the hepatocarcinogenic process.Conclusion: TGF-â1, T3 and alteration of the redox state may be partly responsible for the protective effect of statins on cell proliferation generated by HCB, and may be molecular targets in the treatment of HCC.