Constance LL Saw

Publications (39) View all

• Article: Epigenetic Modifications of Nrf2 by 3,3'-diindolylmethane In Vitro in TRAMP C1 Cell Line and In Vivo TRAMP Prostate Tumors.

  Tien-Yuan Wu, Tin Oo Khor, Zheng-Yuan Su, Constance Lay-Lay Saw, Limin Shu, Ka-Lung Cheung, Ying Huang, Siwang Yu, Ah-Ng Tony Kong
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  ABSTRACT: 3,3'-diindolylmethane (DIM) is currently being investigated in many clinical trials including prostate, breast, and cervical cancers and has been shown to possess anticancer effects in several in vivo and in vitro models. Previously, DIM has been reported to possess cancer chemopreventive effects in prostate carcinogenesis in TRAMP mice; however, the in vivo mechanism is unclear. The present study aims to investigate the in vitro and in vivo epigenetics modulation of DIM in TRAMP-C1 cells and in TRAMP mouse model. In vitro study utilizing TRAMP-C1 cells showed that DIM suppressed DNMT expression and reversed CpG methylation status of Nrf2 resulting in enhanced expression of Nrf2 and Nrf2-target gene NQO1. In vivo study, TRAMP mice fed with DIM-supplemented diet showed much lower incidence of tumorigenesis and metastasis than the untreated control group similar to what was reported previously. DIM increased apoptosis, decreased cell proliferation and enhanced Nrf2 and Nrf2-target gene NQO1 expression in prostate tissues. Importantly, immunohistochemical analysis showed that DIM reduced the global CpG 5-methylcytosine methylation. Focusing on one of the early cancer chemopreventive target gene Nrf2, bisulfite genomic sequencing showed that DIM decreased the methylation status of the first five CpGs of the Nrf2 promoter region, corroborating with the results of in vitro TRAMP-C1 cells. In summary, our current study shows that DIM is a potent cancer chemopreventive agent for prostate cancer and epigenetic modifications of the CpG including Nrf2 could be a potential mechanism by which DIM exerts its chemopreventive effects.
  The AAPS Journal 05/2013; · 5.09 Impact Factor
• Article: Effects of Natural Phytochemicals in Angelica sinensis (Danggui) on Nrf2-mediated Gene Expression of Phase II Drug Metabolizing Enzymes and Anti-inflammation.

  Constance Lay Lay Saw, Qing Wu, Zheng-Yuan Su, Hu Wang, Yinhua Yang, Xiaoting Xu, Ying Huang, Tin Oo Khor, Ah-Ng Tony Kong
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  ABSTRACT: The root of Angelica sinensis (Oliv.) Diels (abbreviated as AS) (Danggui) has a long history in Asian herbal medicine. Recently, it was demonstrated that AS possesses anti-cancer and anti-oxidant activities. Because the transcription factor Nrf2 mediates the expression of many cellular anti-oxidative stress genes, including genes that are involved in phase II drug metabolism and anti-oxidative stress, this study sought to investigate whether pure compounds from AS or an AS extract could activate antioxidant response element (ARE)-mediated gene expression and induce anti-inflammatory activities. Z-Ligustilide (Ligu), 3-butylidenephthalide (Buty) and CO2 supercritical fluid-extracted lipophilic AS extract (SFE) were tested in HepG2-C8 cells stabilized with ARE luciferase reporter gene. Ligu and Buty caused significant toxicity only at 100 μM. All three of the samples induced ARE-luciferase activity; however, SFE at 8.5 µg/mL induced ARE-luciferase activity 2-3 fold more potently than did either of the pure compounds. SFE also significantly increased the endogenous mRNA of Nrf2 and the Nrf2 target anti-oxidative gene NAD(P)H dehydrogenase, quinone 1 (NQO1). The protein expression of NQO1 was also significantly induced by SFE. In RAW 264.7 cells, SFE suppressed LPS-induced IL-1β and TNF-α expression about 2 fold stronger than sulforaphane, whereas both the pure compounds and SFE suppressed inflammatory nitric oxide (NO) production. In summary, our study demonstrates that AS has anti-inflammatory effects and activates the Nrf2 pathway, which protects against oxidative stress. This article is protected by copyright. All rights reserved.
  Biopharmaceutics & Drug Disposition 05/2013; · 2.07 Impact Factor
• Article: Epigenetic reactivation of Nrf2 in murine prostate cancer TRAMP C1 cells by natural phytochemicals Z-ligustilide and Radix Angelica Sinensis via promoter CpG demethylation.

  Zheng-Yuan Su, Tin Oo Khor, Limin Shu, Jong Hun Lee, Constance Lay-Lay Saw, Tien-Yuan Wu, Ying Huang, Nanjoo Suh, Chung S Yang, Allan H Conney, Qing Wu, Ah-Ng Tony Kong
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  ABSTRACT: Cancer development has been linked to mepigenetic modifications of cancer oncogenes and tumor suppressor genes; in advanced metastatic cancers, severe epigenetic modifications are present. We previously demonstrated that the progression of prostate tumors in TRAMP mice is associated with methylation silencing of the Nrf2 promoter and reduced transcription of Nrf2 and Nrf2-target genes. Radix Angelicae sinensis (RAS; Danggui) is a medicinal herb and health food supplement that has been widely used in Asia for centuries. Z-Ligustilide (Lig) is one of the bioactive components of RAS. We investigated the potential of Lig and RAS to restore Nrf2 gene expression through epigenetic modification in TRAMP C1 cells. Lig and RAS induced the mRNA and protein expression of endogenous Nrf2 and Nrf2 downstream target genes, such as HO-1, NQO1, and UGT1A1. Bisulfite genomic sequencing revealed that Lig and RAS treatment decreased methylation of the first 5 CpGs of the Nrf2 promoter. A methylation DNA immunoprecipitation (MeDIP) assay demonstrated that Lig and RAS significantly decreased the relative amount of methylated DNA in the Nrf2 gene promoter region. Lig and RAS also inhibited DNA methyltransferase activity in vitro. Collectively, these results suggest that Lig and RAS are able to demethylate the Nrf2 promoter CpGs, resulting in the re-expression of Nrf2 and Nrf2-target genes. Epigenetic modifications of genes, including Nrf2, may therefore contribute to the overall health benefits of RAS, including the anti-cancer effect of RAS and its bioactive component Lig.
  Chemical Research in Toxicology 02/2013; · 3.78 Impact Factor
• Article: Pharmacokinetics and Pharmacodynamics of Phase II Drug Metabolizing/Antioxidant Enzymes Gene Response by Anticancer Agent Sulforaphane in Rat Lymphocytes.

  Hu Wang, Tin Oo Khor, Qian Yang, Ying Huang, Tien-Yuan Wu, Constance Lay-Lay Saw, Wen Lin, Ioannis P Androulakis, Ah-Ng Tony Kong
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  ABSTRACT: This study assesses the pharmacokinetics (PK) and pharmacodynamics (PD) of Nrf2-mediated increased expression of phase II drug metabolizing enzymes (DME) and antioxidant enzymes which represents an important component of cancer chemoprevention in rat lymphocytes following intravenous (iv) administration of an anticancer phytochemical sulforaphane (SFN). SFN was administered intravenously to four groups of male Sprague-Dawley JVC rats each group comprising four animals. Blood samples were drawn at selected time points. Plasma were obtained from half of each of the blood samples and analyzed using a validated LC-MS/MS method. Lymphocytes were collected from the remaining blood samples using Ficoll-Paque Plus centrifuge medium. Lymphocyte RNAs were extracted and converted to cDNA, quantitative real-time PCR analyses were performed, and fold changes were calculated against those at time zero for the relative expression of Nrf2-target genes of phase II DME/antioxidant enzymes. PK-PD modeling was conducted based on Jusko's indirect response model (IDR) using GastroPlus and bootstrap method. SFN plasma concentration declined biexponentially and the pharmacokinetic parameters were generated. Rat lymphocyte mRNA expression levels showed no change for GSTM1, SOD, NF-κB, UGT1A1, or UGT1A6. Moderate increases (2-5-fold) over the time zero were seen for HO-1, Nrf2, and NQO1, and significant increases (>5-fold) for GSTT1, GPx1, and Maf. PK-PD analyses using GastroPlus and the bootstrap method provided reasonable fitting for the PK and PD profiles and parameter estimates. Our present study shows that SFN could induce Nrf2-mediated phase II DME/antioxidant mRNA expression for NQO1, GSTT1, Nrf2, GPx, Maf, and HO-1 in rat lymphocytes after iv administration, suggesting that Nrf2-mediated mRNA expression in lymphocytes may serve as surrogate biomarkers. The PK-PD IDR model simultaneously linking the plasma concentrations of SFN and the PD response of lymphocyte mRNA expression is valuable for quantitating Nrf2-mediated effects of SFN. This study may provide a conceptual framework for future clinical PK-PD studies of dietary cancer chemopreventive agents in human.
  Molecular Pharmaceutics 08/2012; 9(10):2819-27. · 4.78 Impact Factor
• Article: Anti-cancer and potential chemopreventive actions of ginseng by activating Nrf2 (NFE2L2) anti-oxidative stress/anti-inflammatory pathways

  Constance Lay-Lay Saw, Qing Wu, Ah-NgTony Kong
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  ABSTRACT: This article reviews recent basic and clinical studies of ginseng, particularly the anti-cancer effects and the potential chemopreventive actions by activating the transcriptional factor, nuclear factor (erythroid-derived 2)-like 2 (Nrf2 or NFE2L2)-mediated anti-oxidative stress or anti-inflammatory pathways. Nrf2 is a novel target for cancer prevention as it regulates the antioxidant responsive element (ARE), a critical regulatory element in the promoter region of genes encoding cellular phase II detoxifying and anti-oxidative stress enzymes. The studies on the chemopreventive effects of ginseng or its components/products showed that Nrf2 could also be a target for ginseng's actions. A number of papers also demonstrated the anti-inflammatory effects of ginseng. Targeting Nrf2 pathway is a novel approach to the investigation of ginseng's cancer chemopreventive actions, including some oxidative stress and inflammatory conditions responsible for the initiation, promotion and progression of carcinogenesis.
  Chinese Medicine 04/2012; 5(1):1-7. · 1.79 Impact Factor