Dose-dependent detoxication of the airborne pollutant benzene in a randomized trial of broccoli sprout beverage in Qidong, China

BACKGROUND

Airborne pollutants have collectively been classified as a known human carcinogen and, more broadly, affect the health of hundreds of millions of people worldwide. Benzene is a frequent component of air pollution, and strategies to protect individuals against unavoidable exposure to this and other airborne carcinogens could improve the public's health. Earlier clinical trials in Qidong, China, demonstrated efficacy in enhancing the detoxication of benzene using a broccoli sprout beverage.

OBJECTIVES

A randomized, placebo-controlled, multidose trial of a broccoli sprout beverage was designed to determine the lowest effective concentration that enhances benzene detoxication adjudged by enhanced excretion of the urinary biomarker, S-phenylmercapturic acid (SPMA).

METHODS

Following informed consent, 170 subjects were randomly assigned in 5 blocks of 34 each to drink either a placebo beverage (n = 55) or 1 of 3 graded concentrations of a broccoli sprout beverage [full (n = 25), one-half (n = 35), and one-fifth (n = 55)] for 10 consecutive days. Concentrations of SPMA arising through induced benzene conjugation with glutathione were quantified by MS in sequential 12-h overnight urine collections during the intervention.

RESULTS

MS was also used to quantify urinary sulforaphane metabolites in each dosing regimen that resulted in a median 24-h urinary output of 24.6, 10.3, and 4.3 µmol, respectively, confirming a dose-dependent de-escalation of the inducing principle within the beverage. A statistically significant increase in benzene mercapturic acids in urine was found for the high-dose group (+63.2%) during the 10-d period. The one-half dose (+11.3%) and one-fifth dose groups (-6.4%) were not significantly different from placebo controls.

CONCLUSIONS

An intervention with a broccoli sprout beverage enhanced the detoxication of benzene, an important airborne pollutant, when dosed at a concentration evoking a urinary elimination of ∼25 µmol sulforaphane metabolites per day, and it portends a practical and frugal population-based strategy to attenuate associated long-term health risks of air pollution. This trial was registered at clinicaltrials.gov as NCT02656420.

Abstract A47: Establishing candidate biomarkers for the pharmacodynamic action of sulforaphane in the breast

The goal of this study is the discovery of biomarkers reflecting the pharmacodynamic action of sulforaphane (SFN), initially using normal human mammary epithelial MCF10A cells and then in tissue obtained from healthy patients undergoing reduction mammoplasty. The isothiocyanate SFN is formed by the hydrolysis of glucoraphanin, a water soluble glucosinolate found in cruciferous vegetables with especially high levels measured in 3 day old broccoli sprouts. Chemoprevention by SFN is achieved in part through the upregulation of cytoprotective enzymes via the Keap1/Nrf2 pathway. Preliminary dose response and time course studies in MCF10A cells established that SFN upregulated cytoprotective enzymes as indicated by increased levels of NQO1 transcripts, protein and activity. NQO1 induction was dependent on the Keap1/Nrf2 pathway since NQO1 transcripts, protein and activity were enhanced by KEAP1 siRNA knockdown in MCF10As. For the biomarker discovery phase SFN treated and KEAP1 knockdown MCF10A cells were analyzed by microarray to determine transcriptomic changes in response to pharmacological and genetic stimulation of the Keap1/Nrf2 pathway. The two experimental approaches were analyzed independently and then compared. The predominant class of upregulated genes common to both SFN treatment and KEAP1 knockdown were xenobiotic metabolism and antioxidant genes including NQO1, heme oxygenase (decycling) 1, sequestosome 1, thioredoxin reductase 1 and peroxiredoxin 1. The most highly upregulated genes in this class were the aldo-keto reductase family members including AKR1B1, AKR1B10, AKR1C1 and AKR1C3. Other classes of genes with overlapping regulation were glutathione metabolism genes such as GCLC and GCLM, molecular transport, cell growth and cell death regulation genes. Some members of the xenobiotic metabolism, molecular transport, cell growth and cell death regulation classes of genes were also regulated exclusively by SFN. Additionally histone cluster and chromatin remodeling genes were downregulated by SFN. Potential biomarker genes from the microarray study include NQO1, GCLC, SQSTM1 and AKR1C1. An accompanying proteomic study for biomarker discovery using Stable Isotopic Labeling with Amino Acids in Cell Culture (SILAC) is underway. The transcriptomic and proteomic changes in response to SFN treatment and KEAP1 knockdown will be compared to determine if the changes seen on the transcriptomic level are translated to the proteomic level. Candidate biomarkers identified from microarray and SILAC studies reflecting the pharmacodynamic action of SFN in human cells will be analyzed by Western blot, qRT-PCR and enzyme assays in tissue from reduction mammoplasty

patients. These women have been randomized in a clinical trial to receive either a broccoli sprout preparation containing 100 micromole SFN or a placebo beverage daily for 10 days prior to surgery. Supported by DOD grant BC073262 and NIH grants P50 CA088843 and U54 RR020839.

Citation Information: Cancer Prev Res 2010;3(12 Suppl):A47.

Identification of a novel macrophage phenotype that develops in response to atherogenic phospholipids via Nrf2

RATIONALE

Macrophages change their phenotype and biological functions depending on the microenvironment. In atherosclerosis, oxidative tissue damage accompanies chronic inflammation; however, macrophage phenotypic changes in response to oxidatively modified molecules are not known.

OBJECTIVE

To examine macrophage phenotypic changes in response to oxidized phospholipids that are present in atherosclerotic lesions.

METHODS AND RESULTS

We show that oxidized phospholipid-treated murine macrophages develop into a novel phenotype (Mox) that is strikingly different from the conventional M1 and M2 macrophage phenotypes. Compared to M1 and M2, Mox macrophages show a different gene expression pattern, as well as decreased phagocytotic and chemotactic capacity. Treatment with oxidized phospholipids induces both M1 and M2 macrophages to switch to the Mox phenotype. Whole-genome expression array analysis and subsequent gene ontology clustering revealed that the Mox phenotype was characterized by abundant overrepresentation of Nrf2-mediated expression of redox-regulatory genes. In macrophages isolated from Nrf2(-/-) mice, oxidized phospholipid-induced gene expression and regulation of redox status were compromised. Moreover, we found that Mox macrophages comprise 30% of all macrophages in advanced atherosclerotic lesions of low-density lipoprotein receptor knockout (LDLR(-/-)) mice.

CONCLUSIONS

Together, we identify Nrf2 as a key regulator in the formation of a novel macrophage phenotype (Mox) that develops in response to oxidative tissue damage. The unique biological properties of Mox macrophages suggest this phenotype may play an important role in atherosclerotic lesion development as well as in other settings of chronic inflammation.

Abstract 5700: Establishing candidate biomarkers for the pharmacodynamic action of sulforaphane in the breast

The goal of this study is the discovery of biomarkers reflecting the pharmacodynamic action of sulforaphane (SFN), initially in the normal human mammary epithelial MCF10A cell line and then in tissue obtained from healthy patients undergoing reduction mammoplasty surgery. SFN is formed by the hydrolysis of glucoraphanin, a water soluble glucosinolate found in cruciferous vegetables with especially high levels measured in 3 day old broccoli sprouts. Chemoprevention by SFN is achieved in part through the upregulation of cytoprotective enzymes via the Keap1/Nrf2 pathway. Preliminary dose response and time course studies in MCF10A cells established that SFN upregulated cytoprotective genes as indicated by increased levels of NQO1 transcripts, protein and activity. NQO1 induction is dependent on the Keap1/Nrf2 pathway since NQO1 transcripts, protein and activity were enhanced by KEAP1 siRNA knockdown in MCF10As. For the biomarker discovery phase isobaric tag for relative and absolute quantitation (iTRAQ) was used to quantify global protein changes using mass spectrometry. Two independent 8-plex iTRAQ experiments determined the pharmacological actions of SFN on protein expression, compared to a vehicle control, and the genetic regulation of protein expression following knockdown of KEAP1 compared to a non targeting control siRNA. In both experiments protein expression was analyzed at 12, 24, 48, and 72 hour time points after SFN treatment or KEAP1 knockdown. In addition to confirming NQO1 to be a good candidate biomarker, the iTRAQ analysis identified other upregulated candidates to be aldo-keto reductase family 1 member C1 (AKR1C1), DJ-1 protein, and thioredoxin. NQO1 and AKR1C1 transcripts were also elevated in the MCF10A cells, as assessed by microarray assay. Candidate biomarkers identified from microarray and iTRAQ studies reflecting the pharmacodynamic action of SFN in human cells will be analyzed by Western blot, qRT-PCR and enzyme assays in tissue from reduction mammoplasty patients. These women have been randomized in a clinical trial to receive either a broccoli sprout preparation containing 100 micomole SFN or a placebo beverage daily for 10 days prior to surgery. Supported by P50 CA088843, U54 RR020839 and BC073262.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5700.

Abstract B104: Targeting Nrf2/ARE pathway by inhibition of HDAC in breast cancer prevention

B104

Cancer chemoprevention may be achieved through induction of phase II detoxifying enzymes, a process mediated by the antioxidant response element (ARE) in the promoter region of these genes. A key transcription factor involved in induction of phase II enzymes is nuclear factor erythoid-2 related factor (Nrf2). Although cellular function of Nrf2-Keap1 pathway in human carcinogenesis has been extensively investigated, majority of these studies focus on the negative regulator Keap1, which is responsible for cytoplasmic retention of the Keap1-Nrf2 complex, thereby preventing Nrf2-mediated gene transcription. Given the critical role of lysine acetylation in regulating diverse cellular pathways, we use clinically relevant histone deacetylase (HDAC) inhibitors to explore novel mechanisms that govern Nrf2/ARE pathway. By a global proteomic survey, we have learned that the HDAC inhibitor, vorinostat, induces lysine acetylation of 73 proteins in MDA-MB-231 human breast cancer cells. These proteins include chromatin-associated proteins, transcriptional factors, transcriptional regulators, chaperone proteins, DNA repair enzymes, structural proteins and kinase mediators. Among these proteins, SQSTM1 is of particular interest as a recent study has confirmed its critical function in activation of the Nrf2/ARE pathway. Our work shows that vorinostat down-regulates Keap1 protein and elevates protein expression of Nrf2 and NQO1. Induction of Nrf2 by vorinostat is mediated through SQSTM1 as depletion of SQSTM1 by siRNA diminishes the effect of vorinostat on Nrf2 and NQO1. These findings suggest that therapeutic HDAC inhibitors may be found to be useful as chemopreventive agents for breast cancer and support work to elucidate the roles of lysine acetylation in the Nrf2/ARE dependent gene transcription as an underlying mechanism. Supported by FAMRI, Department of Defense Era of Hope, and NIH CA88843.

Citation Information: Cancer Prev Res 2008;1(7 Suppl):B104.

Nrf2 as a target for cancer chemoprevention

Chemical insults, whether of endogenous or exogenous origins, play major roles in the etiopathogenesis of many cancers. As such, strategies to blunt their formation and limit their damage to biomolecules are a central aspect of chemoprevention. Cellular defenses against such insults are regulated in part by the transcription factor Nrf2. Nrf2, in turn, regulates gene expression through interactions with the ARE (antioxidant-response-element) found in the promoter regions of many cytoprotective genes. Under basal conditions, Nrf2 is tethered in the cytoplasm to an actin binding protein Keap1. Pharmacological and food-derived agents such as dithiolethiones and isothiocyanates trigger the release of Nrf2 from Keap1, allowing it to translocate into the nucleus and stimulate gene transcription. Studies using nrf2-deficient mice have revealed that Nrf2 regulates basal and inducible expression of multiple categories of genes, including xenobiotic-metabolizing enzymes, antioxidant enzymes, molecular chaperones/stress response proteins, as well as proteasome subunits, that collectively reflect the complex and important role Nrf2 plays in the cellular defense against carcinogens. Nrf2 knockout mice are greatly predisposed to chemical-induced DNA damage and exhibit higher susceptibility towards cancer development in several models of chemical carcinogenesis. Nrf2 also mediates protection against oxidative stress and influences inflammatory processes, both of which contribute to carcinogenesis. Observations that nrf2-deficient mice are refractory to the protective actions of some chemopreventive agents highlight the importance of the Keap1-Nrf2-ARE signaling pathway as a molecular target for prevention.

Nefazodone and REM sleep: how do antidepressant drugs decrease REM sleep?

In previous uncontrolled studies, nefazodone, a new antidepressant drug, increased REM sleep or had no effect on REM sleep. We report a double-blind, placebo-controlled, parallel group study on effects of nefazodone (N) on polysomnographic sleep variables in healthy human volunteers. Nefazodone was administered for 16 consecutive days, and nocturnal sleep, as well as multiple sleep latency test (MSLT), was monitored before, during, and after N administration. We found that N had no effect on any measured REM sleep variable including REM sleep duration, REM density, and nocturnal REM sleep distribution. Nefazodone also had no significant effect on nocturnal total sleep time or NREM variables, but increased daytime alertness measured by the MSLT. Since N is a potent serotonin reuptake blocker, the present findings that N had no effect on REM sleep cast doubt on the hypothesis that antidepressant drugs decrease REM sleep by increasing serotonergic neurotransmission. A review of other relevant work also casts doubt on this hypothesis.

Mechanisms of chemoprotection by oltipraz

1,2-Dithiole-3-thiones are five-membered cyclic sulfur-containing compounds with antioxidant, chemotherapeutic, radioprotective and cancer chemoprotective properties. One substituted dithiolethione, oltipraz [5-(2-pyrazinyl)-4-methyl-1,2-dithiole-3-thione], originally developed as an antischistosomal agent, has recently been observed to protect against chemically induced carcinogenesis in lung, trachea, forestomach, colon, breast, skin, liver and urinary bladder in rodents. The induction of electrophilic detoxication enzymes, which result in diminished carcinogen-DNA adduct formation and reduced cytotoxicity, appears to be an important component of the anticarcinogenic action of oltipraz and other dithiolethiones. Phase I trials of oltipraz are presently underway in the United States. Subsequent trials might be most appropriately targeted towards individuals at high risk for occupational or environmental exposures to genotoxic carcinogens.