title: HMG-CoA reductase inhibitor simvastatin overcomes bortezomib-induced apoptosis resistance by disrupting a geranylgeranyl pyrophosphate-dependent survival pathway.
abstract: Simvastatin is a competitive inhibitor of HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway required for the biosynthesis of cholesterol and higher isoprenoids such as geranylgeranyl pyrophosphate (GGPP). Apart from its capacity to lower cholesterol plasma levels and to protect against cardiovascular disease, simvastatin induces apoptosis in various cancer cells. We have generated human Namalwa Burkitt lymphoma cells that display general apoptosis resistance and hyperproliferation due to increased expression and proteolytic activity of 26S proteasomes in response to continuous treatment of the cells with the proteasome inhibitor bortezomib. In these cells, simvastatin does not inhibit proteasome activity, but induces apoptosis, G2/M cell cycle arrest and accumulation of p21(Waf1/Cip1), and effectively inhibits hyperproliferation. These effects are reversed by the addition of GGPP. GGPP-dependent plasma membrane localization of the small GTPase RhoA that is required for RhoA-mediated oncogenic signaling is completely inhibited by simvastatin. Finally, bortezomib but not simvastatin induces accumulation and stabilization of the anti-apoptotic protein Mcl-1, which is known to confer resistance to apoptosis in cancer cells. Thus, simvastatin overcomes bortezomib-induced apoptosis resistance by inhibiting synthesis of GGPP and disrupting a GGPP-dependent survival pathway.
authors.affiliation: Department of Transplantation Immunology, Institute of Immunology, University of Heidelberg, Im Neuenheimer Feld 305, D-69120 Heidelberg, Germany.
authors.forename: Dominik
authors.initials: D
authors.lastname: Fuchs
authors.forename: Carsten
authors.initials: C
authors.lastname: Berges
authors.forename: Gerhard
authors.initials: G
authors.lastname: Opelz
authors.forename: Volker
authors.initials: V
authors.lastname: Daniel
authors.forename: Cord
authors.initials: C
authors.lastname: Naujokat
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001897:Boronic Acids / Q000494:pharmacology; D000069286:Bortezomib; D002051:Burkitt Lymphoma / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D011106:Polyisoprenyl Phosphates / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011719:Pyrazines / Q000494:pharmacology; D019821:Simvastatin / Q000494:pharmacology*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D011106:Polyisoprenyl Phosphates; D019253:Proto-Oncogene Proteins c-bcl-2; D011719:Pyrazines; D000069286:Bortezomib; D019821:Simvastatin; D020742:rhoA GTP-Binding Protein; C002963:geranylgeranyl pyrophosphate