Down-regulation of RhoA is involved in the cytotoxic action of lipophilic statins in HepG2 cells

Asuka Maeda, Takahisa Yano, Yoshinori Itoh, Midori Kakumori, Toshio Kubota, Nobuaki Egashira, Ryozo Oishi

Research output: Contribution to journalArticle

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Abstract

Objective: Hepatotoxicity is one of the major complaints that occur during lipid-lowering therapy with 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, known as statins. We reported earlier that lipophilic but not hydrophilic statins induce apoptosis through inhibition of mevalonate biosynthesis cascade in Chang liver cells. The present study was designed to determine the role for small G protein RhoA in the hepatocytotoxicity of statins. Methods: Statin-induced hepatocytotoxicity in HepG2 cells were assessed by WST-8 cell viability assay, JC-1 mitochondrial membrane potential assay and caspase-3/7 activity assay. Cytosolic RhoA was detected by Western blotting and RhoA activation was measured by ELISA. Results: The lipophilic atorvastatin but not the hydrophilic pravastatin induced the mitochondrial membrane depolarization and the activation of caspase-3/7, which led to cell injury. Supplementation of mevalonate or geranylgeranyl pyrophosphate (GGPP) but not farnesyl pyrophosphate (FPP) reversed these cellular events and cell death induced by atorvastatin. Atorvastatin induced a translocation of RhoA protein into the cytosol and inhibited the activity of the protein. In addition, atorvastatin reduced mitochondrial membrane potential, which was mimicked by GGTase inhibitor GGTI-2147 or the specific RhoA inhibitor such as toxin B and C3 exoenzyme. However, only a few cells revealed mitochondrial membrane depolarization and a loss of viability after exposure to the Rho-kinase inhibitors such as Y-27632 and hydroxy fasudil. Conclusions: RhoA inactivation and to a lesser extent Rho-kinase inhibition after depletion of GGPP is implicated in the etiology of mitochondrial membrane depolarization and subsequent caspase-dependent cell death induced by the lipophilic statin in HepG2 cells.

Original languageEnglish
Pages (from-to)112-118
Number of pages7
JournalAtherosclerosis
Volume208
Issue number1
DOIs
Publication statusPublished - Jan 1 2010

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Hydroxymethylglutaryl-CoA Reductase Inhibitors
Hep G2 Cells
Down-Regulation
Mitochondrial Membranes
Caspase 7
rho-Associated Kinases
Mitochondrial Membrane Potential
Caspase 3
Cell Death
rhoA GTP-Binding Protein
Hydroxymethylglutaryl CoA Reductases
Pravastatin
Mevalonic Acid
Monomeric GTP-Binding Proteins
Caspases
Cytosol
Cell Survival
Western Blotting
Enzyme-Linked Immunosorbent Assay
Apoptosis

All Science Journal Classification (ASJC) codes

  • Cardiology and Cardiovascular Medicine

Cite this

Down-regulation of RhoA is involved in the cytotoxic action of lipophilic statins in HepG2 cells. / Maeda, Asuka; Yano, Takahisa; Itoh, Yoshinori; Kakumori, Midori; Kubota, Toshio; Egashira, Nobuaki; Oishi, Ryozo.

In: Atherosclerosis, Vol. 208, No. 1, 01.01.2010, p. 112-118.

Research output: Contribution to journalArticle

Maeda, Asuka ; Yano, Takahisa ; Itoh, Yoshinori ; Kakumori, Midori ; Kubota, Toshio ; Egashira, Nobuaki ; Oishi, Ryozo. / Down-regulation of RhoA is involved in the cytotoxic action of lipophilic statins in HepG2 cells. In: Atherosclerosis. 2010 ; Vol. 208, No. 1. pp. 112-118.
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T1 - Down-regulation of RhoA is involved in the cytotoxic action of lipophilic statins in HepG2 cells

AU - Maeda, Asuka

AU - Yano, Takahisa

AU - Itoh, Yoshinori

AU - Kakumori, Midori

AU - Kubota, Toshio

AU - Egashira, Nobuaki

AU - Oishi, Ryozo

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AB - Objective: Hepatotoxicity is one of the major complaints that occur during lipid-lowering therapy with 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, known as statins. We reported earlier that lipophilic but not hydrophilic statins induce apoptosis through inhibition of mevalonate biosynthesis cascade in Chang liver cells. The present study was designed to determine the role for small G protein RhoA in the hepatocytotoxicity of statins. Methods: Statin-induced hepatocytotoxicity in HepG2 cells were assessed by WST-8 cell viability assay, JC-1 mitochondrial membrane potential assay and caspase-3/7 activity assay. Cytosolic RhoA was detected by Western blotting and RhoA activation was measured by ELISA. Results: The lipophilic atorvastatin but not the hydrophilic pravastatin induced the mitochondrial membrane depolarization and the activation of caspase-3/7, which led to cell injury. Supplementation of mevalonate or geranylgeranyl pyrophosphate (GGPP) but not farnesyl pyrophosphate (FPP) reversed these cellular events and cell death induced by atorvastatin. Atorvastatin induced a translocation of RhoA protein into the cytosol and inhibited the activity of the protein. In addition, atorvastatin reduced mitochondrial membrane potential, which was mimicked by GGTase inhibitor GGTI-2147 or the specific RhoA inhibitor such as toxin B and C3 exoenzyme. However, only a few cells revealed mitochondrial membrane depolarization and a loss of viability after exposure to the Rho-kinase inhibitors such as Y-27632 and hydroxy fasudil. Conclusions: RhoA inactivation and to a lesser extent Rho-kinase inhibition after depletion of GGPP is implicated in the etiology of mitochondrial membrane depolarization and subsequent caspase-dependent cell death induced by the lipophilic statin in HepG2 cells.

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