farnesyl-pyrophosphate and phenylacetic-acid

Phenylacetate (PA) is a reversible inhibitor of tumor cell growth and an inhibitor of mevalonate pyrophosphate decarboxylase (MPD). We hypothesized that MPD inhibition should lower rates of protein accumulation and accretion of cell number in all cell lines regardless of tumorigenic status or origin of the cell lines. PA treatment inhibited growth of MCF-7, NIH-3T3, Detroit 551, UT-2, NCTC-929, COS-1 and PC-3 cell lines. NCTC-929 cells lack cadherins and Cos-1 cells are deficient in PPARalpha and PPARgamma, proteins suggested to be central to the action of PA. Oxidative metabolism was not impeded by PA treatment. One-dimensional and two-dimensional FACS analysis of BrdU incorporation failed to demonstrate a redistribution of nuclei in the cell cycle or that the rate of cells entering S phase had changed. Time-lapse photo-microscopy studies reveal a process that left condensed nuclei with little or no cytoplasm. However, negative TUNEL assay results and failure to block cell loss with z-VAD-fmk suggest this type of cell death is not typical apoptosis, but cell death is responsible for the lower rates of cell and protein accumulation. Supplementation studies with mevalonate pathway intermediates during inhibition of the mevalonate pathway of cholesterol biosynthesis by lovastatin confirmed MPD as a site of PA inhibition of growth, but in the presence of lovastatin with or without farnesyl pyrophosphate plus geranylgeranyl pyrophosphate, additive inhibition by PA revealed additional site(s). The existence of site(s) in addition to MPD suggests effective PA-based agents might be developed that would not inhibit MPD.

Topics: Animals; Anticholesteremic Agents; Antimetabolites, Antineoplastic; Carboxy-Lyases; Cell Death; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Chlorocebus aethiops; In Situ Nick-End Labeling; Lovastatin; Phenylacetates; Polyisoprenyl Phosphates; Rats; Sesquiterpenes; Time Factors

This study explores the role of mevalonate inhibitors in the activation of NF-kbeta and the induction of inducible nitric oxide synthase (iNOS) and cytokines (TNF-alpha, IL-1beta, and IL-6) in rat primary astrocytes, microglia, and macrophages. Lovastatin and sodium phenylacetate (NaPA) were found to inhibit LPS- and cytokine-mediated production of NO and expression of iNOS in rat primary astrocytes; this inhibition was not due to depletion of end products of mevalonate pathway (e.g., cholesterol and ubiquinone). Reversal of the inhibitory effect of lovastatin on LPS-induced iNOS expression by mevalonate and farnesyl pyrophosphate and reversal of the inhibitory effect of NaPA on LPS-induced iNOS expression by farnesyl pyrophosphate, however, suggests a role of farnesylation in the LPS-mediated induction of iNOS. The inhibition of LPS-mediated induction of iNOS by FPT inhibitor II, an inhibitor of Ras farnesyl protein transferase, suggests that farnesylation of p21(ras) or other proteins regulates the induction of iNOS. Inhibition of LPS-mediated activation of NF-kbeta by lovastatin, NaPA, and FPT inhibitor II in astrocytes indicates that the observed inhibition of iNOS expression is mediated via inhibition of NF-kbeta activation. In addition to iNOS, lovastatin and NaPA also inhibited LPS-induced expression of TNF-alpha, IL-1beta, and IL-6 in rat primary astrocytes, microglia, and macrophages. This study delineates a novel role of the mevalonate pathway in controlling the expression of iNOS and different cytokines in rat astrocytes, microglia, and macrophages that may be important in developing therapeutics against cytokine- and NO-mediated neurodegenerative diseases.

Topics: Alkyl and Aryl Transferases; Animals; Anticholesteremic Agents; Astrocytes; Cells, Cultured; Cytokines; Enzyme Induction; Enzyme Inhibitors; Humans; Interleukin-1; Interleukin-6; Lipopolysaccharides; Lovastatin; Macrophages; Mevalonic Acid; Microglia; Mitogens; NF-kappa B; Nitric Acid; Nitric Oxide Synthase; Phenylacetates; Polyisoprenyl Phosphates; Rats; Sesquiterpenes; Tumor Necrosis Factor-alpha