Cell cycle arrest and apoptosis induction in hepatocellular carcinoma cells by HMG-CoA reductase inhibitors. Synergistic antiproliferative action with ligands of the peripheral benzodiazepine receptor Andreas P. Sutter 1,† , Kerstin Maaser 1,† , Michael Ho ¨pfner 1 , Alexander Huether 1 , Detlef Schuppan 2 , Hans Scheru ¨bl 1, * 1 Charite ´-Universita ¨tsmedizin Berlin, Campus Benjamin Franklin, Medical Clinic I, Berlin, Germany 2 Division of Gastroenterology and Hepatology, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, MA, USA Background/Aims: Hepatocellular carcinoma (HCC) is the fifth most common cause of cancer deaths worldwide. Inhibitors of cholesterol biosynthesis (‘statins’) have been proposed as promising adjunctive anticancer agents to treat HCC, but their mode of action is yet poorly characterized. We additionally investigated the potential benefit of a combination of peripheral benzodiazepine receptor (PBR) ligands and statins. Methods: We analyzed the growth inhibitory effects of PBR ligands, statins, and their combination in two human HCC cell lines. Moreover, we investigated the regulation of cellular cholesterol levels and the expression of 3-hydroxy- 3-methylglutaryl coenzyme-A reductase (HMG-CoAR), the target of statins. Results: Statins inhibited the proliferation of HCC cells by inducing apoptosis and G1/S cell cycle arrest. Statin- induced apoptosis was characterized by a breakdown of the mitochondrial membrane potential, caspase activation and nuclear degradation. Furthermore, activation of ERK1/2 was downregulated while p38MAPK was activated. Synergistic growth inhibition was obtained by the combination of the PBR ligand FGIN-1–27 with statins. PBR ligands induced a decrease of HMG-CoAR expression. This downregulation may be responsible for the enhanced sensitivity of HCC cells to statins. Conclusions: Our data shed light on the signaling cascades mediating statin-induced growth inhibition of HCC cells. Moreover, PBR ligands sensitized HCC cells to statins, suggesting a new strategy to treat HCC. q 2005 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved. Keywords: Apoptosis; Cell cycle; Chemoresistance; Hydroxymethylglutaryl coenzyme-A reductase; Peripheral benzodiazepine receptor 1. Introduction Hepatocellular carcinoma (HCC) is the fifth most common malignancy in the world and is estimated to cause half a million deaths annually. The incidence of HCC is dramatically rising in the USA, Europe and Asia, most probably due to the increasing prevalence of chronic hepatitis C, liver cirrhosis and obesity [1,2]. Unfortunately, the majority of patients suffer from advanced disease at presentation. Apart from chemoembolisation, which Journal of Hepatology 43 (2005) 808–816 www.elsevier.com/locate/jhep 0168-8278/$30.00 q 2005 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.jhep.2005.04.010 Received 10 December 2004; received in revised form 3 March 2005; accepted 4 April 2005; available online 31 May 2005 * Corresponding author. Tel.: C49 30 8445 3534; fax: C49 30 8445 4481. E-mail address: hans.scherubl@charite.de (H. Scheru ¨bl). Abbreviations: ERK, extracellular signal-regulated kinase; FGIN-1–27, N,N-di-n-hexyl-2-(4-fluorophenyl)indole-3-acetamide; HCC, hepatocellu- lar carcinoma; HMG-CoAR, hydroxymethylglutaryl coenzyme A reductase; LDL-R, low density lipoprotein receptor; MAPK, mitogen- activated protein kinase; PBR, peripheral benzodiazepine receptor; PK 11195, 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3- isoquinolinecarboxamide. † These authors contributed equally to this work.