title: Olefin Isomers of a Triazole Bisphosphonate Synergistically Inhibit Geranylgeranyl Diphosphate Synthase.
abstract: The isoprenoid donor for protein geranylgeranylation reactions, geranylgeranyl diphosphate (GGDP), is the product of the enzyme GGDP synthase (GGDPS) that condenses farnesyl diphosphate (FDP) and isopentenyl pyrophosphate. GGDPS inhibition is of interest from a therapeutic perspective for multiple myeloma because we have shown that targeting Rab GTPase geranylgeranylation impairs monoclonal protein trafficking, leading to endoplasmic reticulum stress and apoptosis. We reported a series of triazole bisphosphonate GGDPS inhibitors, of which the most potent was a 3:1 mixture of homogeranyl (HG) and homoneryl (HN) isomers. Here we determined the activity of the individual olefin isomers. Enzymatic and cellular assays revealed that although HN is approximately threefold more potent than HG, HN is not more potent than the original mixture. Studies in which cells were treated with varying concentrations of each isomer alone and in different combinations revealed that the two isomers potentiate the induced-inhibition of protein geranylgeranylation when used in a 3:1 HG:HN combination. A synergistic interaction was observed between the two isomers in the GGDPS enzyme assay. These results suggested that the two isomers bind simultaneously to the enzyme but within different domains. Computational modeling studies revealed that HN is preferred at the FDP site, that HG is preferred at the GGDP site, and that both isomers may bind to the enzyme simultaneously. These studies are the first to report a set of olefin isomers that synergistically inhibit GGDPS, thus establishing a new paradigm for the future development of GGDPS inhibitors.
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.).
authors.forename: Cheryl
authors.initials: C
authors.lastname: Allen
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.).
authors.forename: Sandhya
authors.initials: S
authors.lastname: Kortagere
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.).
authors.forename: Huaxiang
authors.initials: H
authors.lastname: Tong
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.).
authors.forename: Robert A
authors.initials: RA
authors.lastname: Matthiesen
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.).
authors.forename: Joseph I
authors.initials: JI
authors.lastname: Metzger
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.).
authors.forename: David F
authors.initials: DF
authors.lastname: Wiemer
authors.affiliation: Department of Medicine, Roswell Park Cancer Institute, Buffalo, New York (C.A.); Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, Pennsylvania (S.K.); Penn State Cancer Institute, Hershey, Pennsylvania (H.T.); Department of Chemistry, University of Iowa, Iowa City, Iowa (R.A.M., J.I.M., D.F.W.); and Department of Internal Medicine, University of Nebraska Medical Center, Omaha, Nebraska (S.A.H.) sarah.holstein@unmc.edu.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Holstein
mesh_terms: D020134:Catalytic Domain; D045744:Cell Line, Tumor; D004164:Diphosphonates / Q000737:chemistry* / Q000494:pharmacology*; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D051231:Farnesyltranstransferase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007536:Isomerism; D008148:Lovastatin / Q000494:pharmacology; D008958:Models, Molecular; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D012717:Sesquiterpenes / Q000378:metabolism; D014230:Triazoles / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D004164:Diphosphonates; D004791:Enzyme Inhibitors; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; D014230:Triazoles; C004808:farnesyl pyrophosphate; D008148:Lovastatin; D051231:Farnesyltranstransferase; C002963:geranylgeranyl pyrophosphate