Coffee inhibits nuclear factor-kappa B in prostate cancer cells and xenografts.

Chronic inflammation contributes to prostate cancer and the transcription factor Nuclear Factor-kappa B (NF-κB) is constitutively active in most such cancers. We examine the effects of coffee on NF-κB and on the regulation of selected genes in human-derived prostate cancer cells (PC3) and in PC3 xenografts in athymic nude mice. PC3 cells stably transduced with an NF-κB-luciferase reporter were used both in vitro and for xenografts. NF-κB activity was measured by reporter assays, DNA binding and in vivo imaging. Gene expression was measured in PC3 cells, xenografts and tumor microenvironment by low-density arrays. Western blotting of activated caspases was used to quantify apoptosis. Coffee inhibited TNFα-induced NF-κB activity and DNA-binding in PC3 cells. Furthermore, coffee increased apoptosis and modulated expression of a number of inflammation- and cancer-related genes in TNFα-treated PC3 cells. In vivo imaging revealed a 31% lower NF-κB-luciferase activation in the xenografts of the mice receiving 5% coffee compared to control mice. Interestingly, we observed major changes in gene expression in the PC3 cells in xenografts as compared to PC3 cells in vitro. In PC3 xenografts, genes related to inflammation, apoptosis and cytoprotection were down-regulated in mice receiving coffee, and coffee also affected the gene expression in the xenograft microenvironment. Our data demonstrate that coffee inhibits NF-κB activity in PC3 cells in vitro and in xenografts. Furthermore, coffee modulates transcription of genes related to prostate cancer and inflammation. Our results are the first to suggest mechanistic links between coffee consumption and prostate cancer in an experimental mouse model.

Geranylgeraniol oxidase activity involved in oxidative formation of geranylgeranoic acid in human hepatoma cells.

Geranylgeranoic acid (GGA), a 20-carbon acyclic polyprenoic acid (all-trans 3,7,11,15-tetramethyl- 2,4,6,10,14-hexadecatetraenoic acid) and its derivatives were developed as synthetic "acyclic retinoids" for cancer chemoprevention. Previously, we have shown the natural occurrence of GGA in various medicinal herbs and reported enzymatic formation of GGA from geranylgeraniol (GGOH) through geranylgeranial (GGal) by rat liver homogenates. Here, we present several lines of evidence that a putative GGOH oxidase is involved in GGA synthesis by human hepatoma cell lysates. First, conversion of GGOH to GGal did not require exogenous NAD(+), whereas the conversion from GGal to GGA absolutely required additional NAD(+). Second, GGal synthesis from GGOH was coupled with consumption of oxygen from the reaction mixture. Third, GGOH-dependent GGal synthesis activity was proteinase K-resistant and even enhanced by proteinase K treatment; GGOH oxidase activity was enriched in the mitochondrial fraction. Finally, recombinant human monoamine oxidase (MAO)-B, but not MAO-A catalyzed oxidation of GGOH to GGal. These data suggest that a putative mitochondrial GGOH oxidase is involved in the initial step of GGA synthesis from GGOH.

Polished rice as natural sources of cancer-preventing geranylgeranoic acid.

Geranylgeranoic acid, a 20-carbon polyprenoic acid (all-trans 3,7,11,15-tetramethyl-2,4,6,10,14-hexadecatetraenoic acid) and its derivatives were previously developed as synthetic "acyclic retinoids" for cancer chemoprevention. Recently, we demonstrated the natural occurrence of geranylgeranoic acid in various medicinal herbs (Shidoji and Ogawa, 2004). In this present study, we present several lines of evidence to demonstrate that geranylgeranyl diphosphate taken in foods could be metabolized to GGA through geranylgeraniol and geranylgeranyl aldehyde via the following steps: 1) The conversion from geranylgeranyl diphosphate to geranylgeraniol was demonstrated to occur by the action of bovine intestinal alkaline phosphatase, with a K(m) of 46.1 µM. 2) Geranylgeraniol oxidase-mediated conversion of geranylgeraniol to geranylgeranyl aldehyde was revealed in rat liver homogenates, which activity was mainly localized in the mitochondrial fraction. The mitochondrial enzyme showed a K(m) of 92.9 µM. 3) The conversion of geranylgeranyl aldehyde to geranylgeranoic acid by geranylgeranyl aldehyde dehydrogenase in rat liver homogenates was absolutely dependent on exogenously added NAD(+) or NADP(+). The K(m) of the mitochondrial geranylgeranyl aldehyde dehydrogenase was 27.5 µM for geranylgeranyl aldehyde. Taken together, our data suggest that cancer preventive geranylgeranoic acid could be a physiological metabolite from commonly consumed foods.

Increase in plasma concentrations of geranylgeranoic Acid after turmeric tablet intake by healthy volunteers.

Geranylgeranoic acid (GGA) is one of the most potent cancer-preventive acyclic retinoids. GGA has been shown to induce cell death in human hepatoma-derived HuH-7 cells. We have recently reported the natural occurrence of GGA and its related compounds in several medicinal herbs such as turmeric, basil, rosehip, cinnamon and others [Shidoji and Ogawa, J. Lipid Res., 45: 1092-1103, 2004]. In the present study, we performed oral administration of turmeric tablets to healthy volunteers in order to investigate bioavailability of natural GGA. By using liquid chromatography/mass spectrometry, authentic GGA was eluted at a retention time of around 18 min as a negative ion of m/z 303.4. With healthy volunteers, plasma GGA was detected prior to the tablet intake and its concentrations were increased at 2 h after its intake and maintained at higher level until 4 h, suggesting an efficient bioavailability of preformed GGA in the turmeric tablets through oral administration. These results indicated that GGA in the turmeric tablet was absorbed as an intact form from intestinal mucosa. The present study provides a clue to conduct a research for cancer preventive roles of GGA in a number of spices.