Heather Kleiner - Academia.edu (original) (raw)
Papers by Heather Kleiner
This article cites 21 articles, 10 of which you can access for free at:
Cancer research, 2002
A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused are... more A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused areas of solid tumors, which are often most resistant to chemotherapy and radiation. GRP94 is a chaperone protein localized in the endoplasmic reticulum with antiapoptotic properties. We report here that in vitro the proximal murine grp94 promoter is regulated differently from the hypoxia response element fused to the SV40 minimal promoter, with glucose starvation as an inducer of grp94 but a potent repressor of the hypoxia response element/SV40 fusion promoter. Through the use of transgenic mouse models, we showed that LacZ transgene expression driven by the grp94 promoter was strongly activated not only in spontaneous but also in a variety of chemically induced tumors. We additionally discovered that macrophages in the vicinity of malignant tumor showed a high level of transgene expression, consistent with intense beta-galactosidase staining at boundaries between viable tumor cells and ne...
The purpose of the current study was to determine whether a tropical ginger derived compound 1'-a... more The purpose of the current study was to determine whether a tropical ginger derived compound 1'-acetoxychavicol acetate (ACA), suppresses skin tumor promotion in K5.Stat3C mice. In a two-week study in which wild-type (WT) and K5.Stat3C mice were co-treated with either vehicle, ACA, galanga extract, or fluocinolone acetonide (FA) and tetradecanoyl phorbol acetate (TPA), only the galanga extract and FA suppressed TPA-induced skin hyperproliferation and wet weight. None of these agents were effective at suppressing p-Tyr 705 Stat3 expression. However, ACA and FA showed promising inhibitory effects against skin tumorigenesis in K5.Stat3C mice. ACA also suppressed phospho-p65 NF-κB activation, suggesting a potential mechanism for its action.
2,3,5-(Triglutathion-S-yI)hydroquinone [2,3,5-(tFIGSYI)HQ] is a po-tent nephrotoxicant when admin... more 2,3,5-(Triglutathion-S-yI)hydroquinone [2,3,5-(tFIGSYI)HQ] is a po-tent nephrotoxicant when administered to male rats. We now re-port that significant species differences exist in susceptibility to 2,3,5-(tnGSyl)HQ-mediated nephrotoxicity. Metabolism of gluta-thione conjugates involves cleavage of the glutamate and glycine moieties by-y-glutamyltranspeptidase (‘y-GT) and dipeptidases, re-spectively, and the nephrotoxicity of 2,3,5-(triGSyI)HQ can be prevented by the inhibition of renal-y-GT. The resulting cysteine conjugate exhibits a balance between N-acetylation, and N-deacetylation of the mercapturate. We have now determined whether differences in the relative activities of the enzymes in-volved in mercapturic acid biosynthesis in various species contrib-ute to species susceptibility to 2,3,5-(triGSyl)HQ. Renal-y-GT ac-tivity toward 2,3,5-(triGSyl)HQ was highest in the rat (Fischer 344 and Sprague-Dawley) and consistent with the sensitivity of this
![Research paper thumbnail of Aggressive mammary carcinoma progression in Nrf 2 knockout mice treated with 7, 12-dimethylbenz [a] anthracene](https://attachments.academia-assets.com/75240478/thumbnails/1.jpg)
](BMC …, 2010
Background: Activation of nuclear factor erythroid 2-related factor (Nrf2), which belongs to the ... more Background: Activation of nuclear factor erythroid 2-related factor (Nrf2), which belongs to the basic leucine zipper transcription factor family, is a strategy for cancer chemopreventive phytochemicals. It is an important regulator of genes induced by oxidative stress, such as glutathione S-transferases, heme oxygenase-1 and peroxiredoxin 1, by activating the antioxidant response element (ARE). We hypothesized that (1) the citrus coumarin auraptene may suppress premalignant mammary lesions via activation of Nrf2/ARE, and (2) that Nrf2 knockout (KO) mice would be more susceptible to mammary carcinogenesis. Methods: Premalignant lesions and mammary carcinomas were induced by medroxyprogesterone acetate and 7,12-dimethylbenz[a]anthracene treatment. The 10-week pre-malignant study was performed in which 8 groups of 10 each female wild-type (WT) and KO mice were fed either control diet or diets containing auraptene (500 ppm). A carcinogenesis study was also conducted in KO vs. WT mice (n = 30-34). Comparisons between groups were evaluated using ANOVA and Kaplan-Meier Survival statistics, and the Mann-Whitney U-test. Results: All mice treated with carcinogen exhibited premalignant lesions but there were no differences by genotype or diet. In the KO mice, there was a dramatic increase in mammary carcinoma growth rate, size, and weight. Although there was no difference in overall survival, the KO mice had significantly lower mammary tumorfree survival. Also, in the KO mammary carcinomas, the active forms of NF-B and β-catenin were increased 2-fold whereas no differences in oxidized proteins were observed. Many other tumors were observed, including lymphomas. Interestingly, the incidences of lung adenomas in the KO mice were significantly higher than in the WT mice. Conclusions: We report, for the first time, that there was no apparent difference in the formation of premalignant lesions, but rather, the KO mice exhibited rapid, aggressive mammary carcinoma progression.
Background: NF-B is a survival signaling transcription factor complex involved in the malignant p... more Background: NF-B is a survival signaling transcription factor complex involved in the malignant phenotype of many cancers, including squamous cell carcinomas (SCC). The citrus coumarin, auraptene (AUR), and the ethnomedicinal ginger (Alpinia galanga) phenylpropanoid, 1'-acetoxychavicol acetate (ACA), were previously shown to suppress 12-O-tetradecanoylphorbol-13-acetate (TPA) induced mouse skin tumor promotion. The goal of the present study was to determine whether AUR and ACA are effective either alone or in combination with all-trans retinoic acid (ATRA) for suppressing SCC tumor growth. Methods: We first determined the effects of orally administered ACA (100 mg/kg bw) and AUR (200 mg/kg bw) on lipopolysaccharide (LPS)-induced NF-B activation in NF-B-RE-luc (Oslo) luciferase reporter mice. Dietary administration of AUR and ACA ± ATRA was next evaluated in a xenograft mouse model. Female SCID/bg mice were fed diets containing the experimental compounds, injected with 1 × 10 6 SRB12-p9 cells s.c., palpated and weighed twice a week for 28 days following injection. Results: Both ACA and AUR suppressed LPS-induced NF-B activation in the report mice. In the xenograft model, AUR (1000 ppm) and ACA (500 ppm) modestly suppressed tumor volume. However, in combination with ATRA at 5, 10, and 30 ppm, ACA 500 ppm significantly inhibited tumor volume by 56%, 62%, and 98%, respectively. The effect of ATRA alone was 37%, 33%, and 93% inhibition, respectively. AUR 1000 ppm and ATRA 10 ppm were not very effective when administered alone, but when combined, strongly suppressed tumor volume by 84%. Conclusions: Citrus AUR may synergize the tumor suppressive effects of ATRA, while ACA may prolong the inhibitory effects of ATRA. Further studies will be necessary to determine whether these combinations may be useful in the control of human SCC.
The Faseb Journal, Apr 1, 2009
Toxicology Letters, Sep 28, 2007
The tropical ginger compound, 1'-acetoxychavicol ... more The tropical ginger compound, 1'-acetoxychavicol acetate (ACA) possesses cancer chemopreventive properties in several models but its effects on breast cancer have not been fully evaluated. In this study, the effects of ACA on human breast carcinoma-derived MCF-7 and MDA-MB-231 cell viability were assessed using trypan blue exclusion analysis. ACA significantly decreased cell viability in a time- and dose-dependent manner, with effective concentrations 10-50 microM. Apoptosis was confirmed by morphological examination of cells through light microscopy, 4,6-diamidino-2-phenylindole dihydrochloride staining, and annexin V/Alexa Fluor 488 staining visualized using flow cytometry. ACA also increased protein expression of the activated form of caspase-3 in MDA-MB-231 cells. Addition of antioxidants N-acetylcysteine, ascorbic acid, or trolox prevented the loss of viability caused by ACA using trypan blue uptake as a marker. These results suggest ACA may have potential anticancer effects against breast carcinoma cells by inducing apoptosis.
Chem Res Toxicol, 1993
Chemical reaction of 1,4-benzoquinone with GSH gives rise to several multisubstituted hydroquinon... more Chemical reaction of 1,4-benzoquinone with GSH gives rise to several multisubstituted hydroquinone (HQ)-GSH conjugates, each of which causes renal proximal tubular necrosis when administered to male Sprague-Dawley rats. In addition, HQ has recently been reported to be nephrocarcinogenic following long-term exposure in male rats. Since neither the mechanism nor the extent of HQ oxidation and thioether formation in vivo is known, we have assessed both the qualitative and quantitative significance of HQ-thioether formation in vivo and in vitro. HQ (1.8 mmol/kg, ip) was administered to AT-125-pretreated male Sprague-Dawley rats, and bile and urine samples were analyzed with a HPLC-coulometric electrode array system (CEAS) and by liquid chromatography (LC)/continuous-flow fast atom bombardment (CF-FAB) mass spectroscopy. Five S-conjugates of hydroquinone were identified in bile, and one S-conjugate was identified in urine. The major biliary S-conjugate identified was 2-glutathion-S-ylhydroquinone [2-(GSyl)HQ] (18.9 +/- 2.7 mumol). Additional biliary metabolites were 2,5-diglutathion-S-ylhydroquinone [2,5-(diGSyl)HQ] (2.2 +/- 0.6 mumol), 2,6-diglutathion-S-ylhydroquinone [2,6-(diGSyl)HQ] (0.7 +/- 0.3 mumol),2,3,5-triglutathion-S-ylhydroquinone [2,3,5-(triGSyl)HQ] (1.2 +/- 0.1 mumol), and 2-(cystein-S-ylglycyl)hydroquinone. 2-(N-Acetylcystein-S-yl)HQ was the only urinary thioether metabolite (11.4 +/- 3.6 mumol) identified. The quantity of S-conjugates excreted in urine and bile within 4 h of HQ administration [34.3 +/- 4.5 mumol (4.3 +/- 1.1% of dose)] appears sufficient to propose a role for such metabolites in HQ-mediated nephrotoxicity and nephrocarcinogenicity. Rat liver microsomes catalyzed the NADPH-dependent oxidation of HQ (300 microM), in the presence of GSH, to form 2-(GSyl)HQ,2,5-(diGSyl)-HQ, and 2,6-(diGSyl)HQ. A fraction of the microsomal oxidation of HQ appears to be catalyzed by cytochrome(s) P450, although the exact amount remains unclear. 2-(GSyl)HQ,2,5-(diGSyl)-HQ, and 2,6-(diGSyl)HQ (300 microM) also underwent NADPH-dependent oxidation and GSH conjugation in liver microsomes. The extent of the nonenzymatic oxidation of HQ and its GSH conjugates correlated, approximately, with their half-wave oxidation potentials.
Cancer Research
A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused are... more A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused areas of solid tumors, which are often most resistant to chemotherapy and radiation. GRP94 is a chaperone protein localized in the endoplasmic reticulum with antiapoptotic properties. We report here that in vitro the proximal murine grp94 promoter is regulated differently from the hypoxia response element fused to the SV40 minimal promoter, with glucose starvation as an inducer of grp94 but a potent repressor of the hypoxia response element/SV40 fusion promoter. Through the use of transgenic mouse models, we showed that LacZ transgene expression driven by the grp94 promoter was strongly activated not only in spontaneous but also in a variety of chemically induced tumors.
Advances in Experimental Medicine and Biology, 1996
Cancer research, Jan 15, 2002
A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused are... more A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused areas of solid tumors, which are often most resistant to chemotherapy and radiation. GRP94 is a chaperone protein localized in the endoplasmic reticulum with antiapoptotic properties. We report here that in vitro the proximal murine grp94 promoter is regulated differently from the hypoxia response element fused to the SV40 minimal promoter, with glucose starvation as an inducer of grp94 but a potent repressor of the hypoxia response element/SV40 fusion promoter. Through the use of transgenic mouse models, we showed that LacZ transgene expression driven by the grp94 promoter was strongly activated not only in spontaneous but also in a variety of chemically induced tumors. We additionally discovered that macrophages in the vicinity of malignant tumor showed a high level of transgene expression, consistent with intense beta-galactosidase staining at boundaries between viable tumor cells and ne...
Cancer Chemoprevention, 2004
Toxicology Letters, 2009
Naturally occurring coumarins possess anti-carcinogenic activities in part by inducing carcinogen... more Naturally occurring coumarins possess anti-carcinogenic activities in part by inducing carcinogendetoxifying enzymes glutathione S-transferase (GST) and/or NAD(P)H quinone oxidoreductase (NQO1). Our goal was to determine whether citrus coumarins induce hepatic GST and/or NQO1 via activation of Nrf2 and the antioxidant response element. First, HepG2 cells stably transfected with the ARE and a green fluorescent protein (GFP) reporter were treated with increasing concentrations of coumarins and compared to positive controls. tert-butylhydroquinone (TBHQ) and oltipraz increased GFP fluorescence, as did coumarin, limettin, auraptene, imperatorin, and 7,8benzoflavone, suggesting that they activate the ARE, whereas isopimpinellin did not increase GFP fluorescence. Next, the effects of orally-administered coumarins and oltipraz on hepatic GST and NQO1 activities were compared in Nrf2 knockout mice or Nrf2 heterozygous mice exhibiting the wild-type phenotype. Oltipraz, auraptene, imperatorin, isopimpinellin, and auraptene all significantly increased liver cytosolic GST activities in Nrf2 heterozygous mice. This effect was abrogated in Nrf2 (−/−) mice dosed with oltipraz, attenuated in mice Nrf2(−/−) mice treated with auraptene and imperatorin, and still significant in Nrf2(−/−) mice treated with isopimpinellin. Of these compounds, only isopimpinellin significantly increased liver cytosolic NQO1 activities, and this effect was not attenuated in Nrf2(−/−) mice. These results strongly suggest that imperatorin and auraptene induce murine liver cytosolic GST activities via the Nrf2/ARE mechanism. Although structurally similar, isopimpinellin did not appear to activate HepG2-ARE-GFP and the Nrf2 knockout mouse study suggests that isopimpinellin may induce GST and NQO1 via additional mechanisms.
Toxicology Letters, 2007
The tropical ginger compound, 1'-acetoxychavicol ... more The tropical ginger compound, 1'-acetoxychavicol acetate (ACA) possesses cancer chemopreventive properties in several models but its effects on breast cancer have not been fully evaluated. In this study, the effects of ACA on human breast carcinoma-derived MCF-7 and MDA-MB-231 cell viability were assessed using trypan blue exclusion analysis. ACA significantly decreased cell viability in a time- and dose-dependent manner, with effective concentrations 10-50 microM. Apoptosis was confirmed by morphological examination of cells through light microscopy, 4,6-diamidino-2-phenylindole dihydrochloride staining, and annexin V/Alexa Fluor 488 staining visualized using flow cytometry. ACA also increased protein expression of the activated form of caspase-3 in MDA-MB-231 cells. Addition of antioxidants N-acetylcysteine, ascorbic acid, or trolox prevented the loss of viability caused by ACA using trypan blue uptake as a marker. These results suggest ACA may have potential anticancer effects against breast carcinoma cells by inducing apoptosis.
Toxicology and Applied Pharmacology, 2008
Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme fa... more Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme families involved in carcinogen metabolism. Generally, P450s play activation or detoxifying roles while GSTs act primarily as detoxifying enzymes. We previously demonstrated that oral administration of the linear furanocoumarins, isopimpinellin and imperatorin, modulated P450 and GST activities in various tissues of mice. The purpose of the present study was to compare a broader range of naturally occurring coumarins (simple coumarins, and furanocoumarins of the linear and angular type) for their abilities to modulate hepatic drug-metabolizing enzymes when administered orally to mice. We now report that all of the different coumarins tested (coumarin, limettin, auraptene, angelicin, bergamottin, imperatorin and isopimpinellin) induced hepatic GST activities, whereas the linear furanocoumarins possessed the greatest abilities to induce hepatic P450 activities, in particular P450 2B and 3A. In both cases, this corresponded to an increase in protein expression of the enzymes. Induction of P4502B10, 3A11, and 2C9 by xenobiotics often is a result of activation of the pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Using a pregnane X receptor reporter system, our results demonstrated that isopimpinellin activated both PXR and its human ortholog SXR by recruiting coactivator SRC-1 in transfected cells. In CAR transfection assays, isopimpinellin counteracted the inhibitory effect of androstanol on full-length mCAR, a Gal4-mCAR ligand-binding domain fusion, and restored coactivator binding. Orally administered isopimpinellin induced hepatic mRNA expression of Cyp2b10, Cyp3a11, and GSTain CAR(+/+) wild-type mice. In contrast, the induction of Cyp2b10 mRNA by isopimpinellin was attenuated in the CAR(-/-) mice, suggesting that isopimpinellin induces Cyp2b10 via the CAR receptor. Overall, the current data indicate that naturally occurring coumarins have diverse activities in terms of inducing various xenobiotic metabolizing enzymes based on their chemical structure.
Pharmacogenetics and Genomics, 2005
Coumarins are naturally occurring chemicals with potential as chemopreventive agents, several wit... more Coumarins are naturally occurring chemicals with potential as chemopreventive agents, several with known action on the cytochrome P450 1A family. We examined whether cytochrome P450 1B1 (CYP1B1) was inhibited by coumarins, whether such inhibition was competitive, and whether inhibition varied between common polymorphic variants of this enzyme. We tested the inhibition properties of four coumarins, bergamottin, isopimpinellin, isoimperatorin, and imperatorin in an assay for oxidation of (-)benzo[a]pyrene-7R-trans-7,8-dihyrodiol (B[a]P-7,8-diol) by CYP1B1 using yeast-microsome expressed enzymes. These assays were performed with wild-type enzyme and five single-amino acid polymorphic variants. All four coumarins are competitive inhibitors of CYP1B1, with Ki values equal to 587, 11, 6 and 1 muM respectively. Inhibition parameters were consistent between five haplotypes of CYP1B1, three representing common haplotypes in Asians, African-Americans and European-Americans, and two with baseline kinetic parameters previously shown to be potentially different from wild-type. Coumarins are capable of inhibiting carcinogen activation by CYP1B1 with varying potencies, and their efficacy as chemopreventive agents is not likely to be affected by polymorphism in this enzyme.
This article cites 21 articles, 10 of which you can access for free at:
Cancer research, 2002
A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused are... more A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused areas of solid tumors, which are often most resistant to chemotherapy and radiation. GRP94 is a chaperone protein localized in the endoplasmic reticulum with antiapoptotic properties. We report here that in vitro the proximal murine grp94 promoter is regulated differently from the hypoxia response element fused to the SV40 minimal promoter, with glucose starvation as an inducer of grp94 but a potent repressor of the hypoxia response element/SV40 fusion promoter. Through the use of transgenic mouse models, we showed that LacZ transgene expression driven by the grp94 promoter was strongly activated not only in spontaneous but also in a variety of chemically induced tumors. We additionally discovered that macrophages in the vicinity of malignant tumor showed a high level of transgene expression, consistent with intense beta-galactosidase staining at boundaries between viable tumor cells and ne...
The purpose of the current study was to determine whether a tropical ginger derived compound 1'-a... more The purpose of the current study was to determine whether a tropical ginger derived compound 1'-acetoxychavicol acetate (ACA), suppresses skin tumor promotion in K5.Stat3C mice. In a two-week study in which wild-type (WT) and K5.Stat3C mice were co-treated with either vehicle, ACA, galanga extract, or fluocinolone acetonide (FA) and tetradecanoyl phorbol acetate (TPA), only the galanga extract and FA suppressed TPA-induced skin hyperproliferation and wet weight. None of these agents were effective at suppressing p-Tyr 705 Stat3 expression. However, ACA and FA showed promising inhibitory effects against skin tumorigenesis in K5.Stat3C mice. ACA also suppressed phospho-p65 NF-κB activation, suggesting a potential mechanism for its action.
2,3,5-(Triglutathion-S-yI)hydroquinone [2,3,5-(tFIGSYI)HQ] is a po-tent nephrotoxicant when admin... more 2,3,5-(Triglutathion-S-yI)hydroquinone [2,3,5-(tFIGSYI)HQ] is a po-tent nephrotoxicant when administered to male rats. We now re-port that significant species differences exist in susceptibility to 2,3,5-(tnGSyl)HQ-mediated nephrotoxicity. Metabolism of gluta-thione conjugates involves cleavage of the glutamate and glycine moieties by-y-glutamyltranspeptidase (‘y-GT) and dipeptidases, re-spectively, and the nephrotoxicity of 2,3,5-(triGSyI)HQ can be prevented by the inhibition of renal-y-GT. The resulting cysteine conjugate exhibits a balance between N-acetylation, and N-deacetylation of the mercapturate. We have now determined whether differences in the relative activities of the enzymes in-volved in mercapturic acid biosynthesis in various species contrib-ute to species susceptibility to 2,3,5-(triGSyl)HQ. Renal-y-GT ac-tivity toward 2,3,5-(triGSyl)HQ was highest in the rat (Fischer 344 and Sprague-Dawley) and consistent with the sensitivity of this
BMC …, 2010
Background: Activation of nuclear factor erythroid 2-related factor (Nrf2), which belongs to the ... more Background: Activation of nuclear factor erythroid 2-related factor (Nrf2), which belongs to the basic leucine zipper transcription factor family, is a strategy for cancer chemopreventive phytochemicals. It is an important regulator of genes induced by oxidative stress, such as glutathione S-transferases, heme oxygenase-1 and peroxiredoxin 1, by activating the antioxidant response element (ARE). We hypothesized that (1) the citrus coumarin auraptene may suppress premalignant mammary lesions via activation of Nrf2/ARE, and (2) that Nrf2 knockout (KO) mice would be more susceptible to mammary carcinogenesis. Methods: Premalignant lesions and mammary carcinomas were induced by medroxyprogesterone acetate and 7,12-dimethylbenz[a]anthracene treatment. The 10-week pre-malignant study was performed in which 8 groups of 10 each female wild-type (WT) and KO mice were fed either control diet or diets containing auraptene (500 ppm). A carcinogenesis study was also conducted in KO vs. WT mice (n = 30-34). Comparisons between groups were evaluated using ANOVA and Kaplan-Meier Survival statistics, and the Mann-Whitney U-test. Results: All mice treated with carcinogen exhibited premalignant lesions but there were no differences by genotype or diet. In the KO mice, there was a dramatic increase in mammary carcinoma growth rate, size, and weight. Although there was no difference in overall survival, the KO mice had significantly lower mammary tumorfree survival. Also, in the KO mammary carcinomas, the active forms of NF-B and β-catenin were increased 2-fold whereas no differences in oxidized proteins were observed. Many other tumors were observed, including lymphomas. Interestingly, the incidences of lung adenomas in the KO mice were significantly higher than in the WT mice. Conclusions: We report, for the first time, that there was no apparent difference in the formation of premalignant lesions, but rather, the KO mice exhibited rapid, aggressive mammary carcinoma progression.
Background: NF-B is a survival signaling transcription factor complex involved in the malignant p... more Background: NF-B is a survival signaling transcription factor complex involved in the malignant phenotype of many cancers, including squamous cell carcinomas (SCC). The citrus coumarin, auraptene (AUR), and the ethnomedicinal ginger (Alpinia galanga) phenylpropanoid, 1'-acetoxychavicol acetate (ACA), were previously shown to suppress 12-O-tetradecanoylphorbol-13-acetate (TPA) induced mouse skin tumor promotion. The goal of the present study was to determine whether AUR and ACA are effective either alone or in combination with all-trans retinoic acid (ATRA) for suppressing SCC tumor growth. Methods: We first determined the effects of orally administered ACA (100 mg/kg bw) and AUR (200 mg/kg bw) on lipopolysaccharide (LPS)-induced NF-B activation in NF-B-RE-luc (Oslo) luciferase reporter mice. Dietary administration of AUR and ACA ± ATRA was next evaluated in a xenograft mouse model. Female SCID/bg mice were fed diets containing the experimental compounds, injected with 1 × 10 6 SRB12-p9 cells s.c., palpated and weighed twice a week for 28 days following injection. Results: Both ACA and AUR suppressed LPS-induced NF-B activation in the report mice. In the xenograft model, AUR (1000 ppm) and ACA (500 ppm) modestly suppressed tumor volume. However, in combination with ATRA at 5, 10, and 30 ppm, ACA 500 ppm significantly inhibited tumor volume by 56%, 62%, and 98%, respectively. The effect of ATRA alone was 37%, 33%, and 93% inhibition, respectively. AUR 1000 ppm and ATRA 10 ppm were not very effective when administered alone, but when combined, strongly suppressed tumor volume by 84%. Conclusions: Citrus AUR may synergize the tumor suppressive effects of ATRA, while ACA may prolong the inhibitory effects of ATRA. Further studies will be necessary to determine whether these combinations may be useful in the control of human SCC.
The Faseb Journal, Apr 1, 2009
Toxicology Letters, Sep 28, 2007
The tropical ginger compound, 1'-acetoxychavicol ... more The tropical ginger compound, 1'-acetoxychavicol acetate (ACA) possesses cancer chemopreventive properties in several models but its effects on breast cancer have not been fully evaluated. In this study, the effects of ACA on human breast carcinoma-derived MCF-7 and MDA-MB-231 cell viability were assessed using trypan blue exclusion analysis. ACA significantly decreased cell viability in a time- and dose-dependent manner, with effective concentrations 10-50 microM. Apoptosis was confirmed by morphological examination of cells through light microscopy, 4,6-diamidino-2-phenylindole dihydrochloride staining, and annexin V/Alexa Fluor 488 staining visualized using flow cytometry. ACA also increased protein expression of the activated form of caspase-3 in MDA-MB-231 cells. Addition of antioxidants N-acetylcysteine, ascorbic acid, or trolox prevented the loss of viability caused by ACA using trypan blue uptake as a marker. These results suggest ACA may have potential anticancer effects against breast carcinoma cells by inducing apoptosis.
Chem Res Toxicol, 1993
Chemical reaction of 1,4-benzoquinone with GSH gives rise to several multisubstituted hydroquinon... more Chemical reaction of 1,4-benzoquinone with GSH gives rise to several multisubstituted hydroquinone (HQ)-GSH conjugates, each of which causes renal proximal tubular necrosis when administered to male Sprague-Dawley rats. In addition, HQ has recently been reported to be nephrocarcinogenic following long-term exposure in male rats. Since neither the mechanism nor the extent of HQ oxidation and thioether formation in vivo is known, we have assessed both the qualitative and quantitative significance of HQ-thioether formation in vivo and in vitro. HQ (1.8 mmol/kg, ip) was administered to AT-125-pretreated male Sprague-Dawley rats, and bile and urine samples were analyzed with a HPLC-coulometric electrode array system (CEAS) and by liquid chromatography (LC)/continuous-flow fast atom bombardment (CF-FAB) mass spectroscopy. Five S-conjugates of hydroquinone were identified in bile, and one S-conjugate was identified in urine. The major biliary S-conjugate identified was 2-glutathion-S-ylhydroquinone [2-(GSyl)HQ] (18.9 +/- 2.7 mumol). Additional biliary metabolites were 2,5-diglutathion-S-ylhydroquinone [2,5-(diGSyl)HQ] (2.2 +/- 0.6 mumol), 2,6-diglutathion-S-ylhydroquinone [2,6-(diGSyl)HQ] (0.7 +/- 0.3 mumol),2,3,5-triglutathion-S-ylhydroquinone [2,3,5-(triGSyl)HQ] (1.2 +/- 0.1 mumol), and 2-(cystein-S-ylglycyl)hydroquinone. 2-(N-Acetylcystein-S-yl)HQ was the only urinary thioether metabolite (11.4 +/- 3.6 mumol) identified. The quantity of S-conjugates excreted in urine and bile within 4 h of HQ administration [34.3 +/- 4.5 mumol (4.3 +/- 1.1% of dose)] appears sufficient to propose a role for such metabolites in HQ-mediated nephrotoxicity and nephrocarcinogenicity. Rat liver microsomes catalyzed the NADPH-dependent oxidation of HQ (300 microM), in the presence of GSH, to form 2-(GSyl)HQ,2,5-(diGSyl)-HQ, and 2,6-(diGSyl)HQ. A fraction of the microsomal oxidation of HQ appears to be catalyzed by cytochrome(s) P450, although the exact amount remains unclear. 2-(GSyl)HQ,2,5-(diGSyl)-HQ, and 2,6-(diGSyl)HQ (300 microM) also underwent NADPH-dependent oxidation and GSH conjugation in liver microsomes. The extent of the nonenzymatic oxidation of HQ and its GSH conjugates correlated, approximately, with their half-wave oxidation potentials.
Cancer Research
A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused are... more A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused areas of solid tumors, which are often most resistant to chemotherapy and radiation. GRP94 is a chaperone protein localized in the endoplasmic reticulum with antiapoptotic properties. We report here that in vitro the proximal murine grp94 promoter is regulated differently from the hypoxia response element fused to the SV40 minimal promoter, with glucose starvation as an inducer of grp94 but a potent repressor of the hypoxia response element/SV40 fusion promoter. Through the use of transgenic mouse models, we showed that LacZ transgene expression driven by the grp94 promoter was strongly activated not only in spontaneous but also in a variety of chemically induced tumors.
Advances in Experimental Medicine and Biology, 1996
Cancer research, Jan 15, 2002
A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused are... more A major challenge in treating cancer is the difficulty of bringing therapy to poorly perfused areas of solid tumors, which are often most resistant to chemotherapy and radiation. GRP94 is a chaperone protein localized in the endoplasmic reticulum with antiapoptotic properties. We report here that in vitro the proximal murine grp94 promoter is regulated differently from the hypoxia response element fused to the SV40 minimal promoter, with glucose starvation as an inducer of grp94 but a potent repressor of the hypoxia response element/SV40 fusion promoter. Through the use of transgenic mouse models, we showed that LacZ transgene expression driven by the grp94 promoter was strongly activated not only in spontaneous but also in a variety of chemically induced tumors. We additionally discovered that macrophages in the vicinity of malignant tumor showed a high level of transgene expression, consistent with intense beta-galactosidase staining at boundaries between viable tumor cells and ne...
Cancer Chemoprevention, 2004
Toxicology Letters, 2009
Naturally occurring coumarins possess anti-carcinogenic activities in part by inducing carcinogen... more Naturally occurring coumarins possess anti-carcinogenic activities in part by inducing carcinogendetoxifying enzymes glutathione S-transferase (GST) and/or NAD(P)H quinone oxidoreductase (NQO1). Our goal was to determine whether citrus coumarins induce hepatic GST and/or NQO1 via activation of Nrf2 and the antioxidant response element. First, HepG2 cells stably transfected with the ARE and a green fluorescent protein (GFP) reporter were treated with increasing concentrations of coumarins and compared to positive controls. tert-butylhydroquinone (TBHQ) and oltipraz increased GFP fluorescence, as did coumarin, limettin, auraptene, imperatorin, and 7,8benzoflavone, suggesting that they activate the ARE, whereas isopimpinellin did not increase GFP fluorescence. Next, the effects of orally-administered coumarins and oltipraz on hepatic GST and NQO1 activities were compared in Nrf2 knockout mice or Nrf2 heterozygous mice exhibiting the wild-type phenotype. Oltipraz, auraptene, imperatorin, isopimpinellin, and auraptene all significantly increased liver cytosolic GST activities in Nrf2 heterozygous mice. This effect was abrogated in Nrf2 (−/−) mice dosed with oltipraz, attenuated in mice Nrf2(−/−) mice treated with auraptene and imperatorin, and still significant in Nrf2(−/−) mice treated with isopimpinellin. Of these compounds, only isopimpinellin significantly increased liver cytosolic NQO1 activities, and this effect was not attenuated in Nrf2(−/−) mice. These results strongly suggest that imperatorin and auraptene induce murine liver cytosolic GST activities via the Nrf2/ARE mechanism. Although structurally similar, isopimpinellin did not appear to activate HepG2-ARE-GFP and the Nrf2 knockout mouse study suggests that isopimpinellin may induce GST and NQO1 via additional mechanisms.
Toxicology Letters, 2007
The tropical ginger compound, 1'-acetoxychavicol ... more The tropical ginger compound, 1'-acetoxychavicol acetate (ACA) possesses cancer chemopreventive properties in several models but its effects on breast cancer have not been fully evaluated. In this study, the effects of ACA on human breast carcinoma-derived MCF-7 and MDA-MB-231 cell viability were assessed using trypan blue exclusion analysis. ACA significantly decreased cell viability in a time- and dose-dependent manner, with effective concentrations 10-50 microM. Apoptosis was confirmed by morphological examination of cells through light microscopy, 4,6-diamidino-2-phenylindole dihydrochloride staining, and annexin V/Alexa Fluor 488 staining visualized using flow cytometry. ACA also increased protein expression of the activated form of caspase-3 in MDA-MB-231 cells. Addition of antioxidants N-acetylcysteine, ascorbic acid, or trolox prevented the loss of viability caused by ACA using trypan blue uptake as a marker. These results suggest ACA may have potential anticancer effects against breast carcinoma cells by inducing apoptosis.
Toxicology and Applied Pharmacology, 2008
Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme fa... more Cytochromes P450 (P450s) and glutathione S-transferases (GSTs) constitute two important enzyme families involved in carcinogen metabolism. Generally, P450s play activation or detoxifying roles while GSTs act primarily as detoxifying enzymes. We previously demonstrated that oral administration of the linear furanocoumarins, isopimpinellin and imperatorin, modulated P450 and GST activities in various tissues of mice. The purpose of the present study was to compare a broader range of naturally occurring coumarins (simple coumarins, and furanocoumarins of the linear and angular type) for their abilities to modulate hepatic drug-metabolizing enzymes when administered orally to mice. We now report that all of the different coumarins tested (coumarin, limettin, auraptene, angelicin, bergamottin, imperatorin and isopimpinellin) induced hepatic GST activities, whereas the linear furanocoumarins possessed the greatest abilities to induce hepatic P450 activities, in particular P450 2B and 3A. In both cases, this corresponded to an increase in protein expression of the enzymes. Induction of P4502B10, 3A11, and 2C9 by xenobiotics often is a result of activation of the pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Using a pregnane X receptor reporter system, our results demonstrated that isopimpinellin activated both PXR and its human ortholog SXR by recruiting coactivator SRC-1 in transfected cells. In CAR transfection assays, isopimpinellin counteracted the inhibitory effect of androstanol on full-length mCAR, a Gal4-mCAR ligand-binding domain fusion, and restored coactivator binding. Orally administered isopimpinellin induced hepatic mRNA expression of Cyp2b10, Cyp3a11, and GSTain CAR(+/+) wild-type mice. In contrast, the induction of Cyp2b10 mRNA by isopimpinellin was attenuated in the CAR(-/-) mice, suggesting that isopimpinellin induces Cyp2b10 via the CAR receptor. Overall, the current data indicate that naturally occurring coumarins have diverse activities in terms of inducing various xenobiotic metabolizing enzymes based on their chemical structure.
Pharmacogenetics and Genomics, 2005
Coumarins are naturally occurring chemicals with potential as chemopreventive agents, several wit... more Coumarins are naturally occurring chemicals with potential as chemopreventive agents, several with known action on the cytochrome P450 1A family. We examined whether cytochrome P450 1B1 (CYP1B1) was inhibited by coumarins, whether such inhibition was competitive, and whether inhibition varied between common polymorphic variants of this enzyme. We tested the inhibition properties of four coumarins, bergamottin, isopimpinellin, isoimperatorin, and imperatorin in an assay for oxidation of (-)benzo[a]pyrene-7R-trans-7,8-dihyrodiol (B[a]P-7,8-diol) by CYP1B1 using yeast-microsome expressed enzymes. These assays were performed with wild-type enzyme and five single-amino acid polymorphic variants. All four coumarins are competitive inhibitors of CYP1B1, with Ki values equal to 587, 11, 6 and 1 muM respectively. Inhibition parameters were consistent between five haplotypes of CYP1B1, three representing common haplotypes in Asians, African-Americans and European-Americans, and two with baseline kinetic parameters previously shown to be potentially different from wild-type. Coumarins are capable of inhibiting carcinogen activation by CYP1B1 with varying potencies, and their efficacy as chemopreventive agents is not likely to be affected by polymorphism in this enzyme.