In vivo Pharmacokinetics, Activation of MAPK Signaling and Induction of Phase II/III Drug Metabolizing Enzymes/Transporters by Cancer Chemopreventive Compound BHA in the Mice

Hu, Rong,Shen, Guoxiang,Yerramilli, Usha Rao,Lin, Wen,Xu, Changjiang,Nair, Sujit,Kong, Ah-Ng Tony The Pharmaceutical Society of Korea 2006 Archives of Pharmacal Research Vol.29 No.10

Phenolic antioxidant butylated hydroxyanisole (BHA) is a commonly used food preservative with broad biological activities, including protection against chemical-induced carcinogenesis, acute toxicity of chemicals, modulation of macromolecule synthesis and immune response, induction of phase II detoxifying enzymes, as well as its undesirable potential tumor-promoting activities. Understanding the molecular basis underlying these diverse biological actions of BHA is thus of great importance. Here we studied the pharmacokinetics, activation of signaling kinases and induction of phase II/III drug metabolizing enzymes/transporter gene expression by BHA in the mice. The peak plasma concentration of BHA achieved in our current study after oral administration of 200 mg/kg BHA was around $10\;{\mu}M$. This in vivo concentration might offer some insights for the many in vitro cell culture studies on signal transduction and induction of phase II genes using similar concentrations. The oral bioavailability (F) of BHA was about 43% in the mice. In the mouse liver, BHA induced the expression of phase II genes including NQO-1, HO-1, ${\gamma}-GCS$, GST-pi and UGT 1A6, as well as some of the phase III transporter genes, such as MRP1 and Slco1b2. In addition, BHA activated distinct mitogen-activated protein kinases (MAPKs), c-Jun N-terminal kinase (JNK), extracellular signal-regulated protein kinase (ERK), as well as p38, suggesting that the MAPK pathways may play an important role in early signaling events leading to the regulation of gene expression including phase II drug metabolizing and some phase III drug transporter genes. This is the first study to demonstrate the in vivo pharmacokinetics of BHA, the in vivo activation of MAPK signaling proteins, as well as the in vivo induction of Phase II/III drug metabolizing enzymes/transporters in the mouse livers.

Regulation of Nrf2 Transactivation Domain Activity by p160 RAC3/SRC3 and Other Nuclear Co-Regulators

Lin, Wen,Shen, Guoxiang,Yuan, Xiaoling,Jain, Mohit R.,Yu, Siwang,Zhang, Aihua,Chen, J. Don,Kong, Ah-Ng Tony Korean Society for Biochemistry and Molecular Biol 2006 Journal of biochemistry and molecular biology Vol.39 No.3

Transcription factor NF-E2-related factor 2 (Nrf2) regulates the induction of Phase II detoxifying enzymes and antioxidant enzymes in response to many cancer chemopreventive compounds. In this study, we investigated the role of receptor associated coactivator (RAC3) or steroid receptor coactivator-3 (SRC3) and other nuclear co-regulators including CBP/p300 (CREB-binding protein), CARM1 (Coactivator-associated arginine methyltransferase), PRMT1 (Protein arginine methyl-transferase 1), and p/CAF (p300/CBP-associated factor) in the transcriptional activation of a chimeric Gal4-Nrf2-Luciferase system containing the transactivation domain (TAD) of Nrf2 in HepG2 cells. The results indicated that RAC3 up-regulated the transactivation activity of Gal4-Nrf2-(1-370) in a dose-dependent manner. The enhancement of transactivation domain activity of Gal4-Nrf2-(1-370) by RAC3 was dampened in the presence of dominant negative mutants of RAC3. Next we studied the effects of other nuclear co-regulators including CBP/p300, CARM1, PRMT1 and p/CAF, and the results showed that they had different level of positive effects on this transactivation domain activity of Gal4-Nrf2-(1-370). But importantly, synergistic effects of these co-regulators in the presence of RAC3/SRC3 on the transactivation activity of Gal4-Nrf2-(1-370) were observed. In summary, our present study showed for the first time that the 160 RAC3/SRC3 is involved in the functional transactivation of TAD of Nrf2 and that the other nuclear co-regulators such as CBP/p300, CARM1, PRMT1 and p/CAF can also transcriptionally activate this TAD of Nrf2 and that they could further enhance the transactivation activity mediated by RAC3/SRC3.

In vivo Pharmacokinetics, Activation of MAPK Signaling and Induction of Phase II/III 911Drug Metabolizing Enzymes/Transporters by Cancer Chemopreventive CompoundBHA in the Mice

Rong Hu,Guoxiang Shen,Usha Rao Yerramilli,Wen Lin,Changjiang Xu,Sujit Nair,Ah-Ng Tony Kong 대한약학회 2006 Archives of Pharmacal Research Vol.29 No.10

Phenolic antioxidant butylated hydroxyanisole (BHA) is a commonly used food preservative with broad biological activities, including protection against chemical-induced carcinogenesis, acute toxicity of chemicals, modulation of macromolecule synthesis and immune response, induction of phase II detoxifying enzymes, as well as its undesirable potential tumor-promoting activities. Understanding the molecular basis underlying these diverse biological actions of BHA is thus of great importance. Here we studied the pharmacokinetics, activation of signaling kinases and induction of phase II/III drug metabolizing enzymes/transporter gene expression by BHA in the mice. The peak plasma concentration of BHA achieved in our current study after oral administration of 200 mg/kg BHA was around 10 μM. This in vivo concentration might offer some insights for the many in vitro cell culture studies on signal transduction and induction of phase II genes using similar concentrations. The oral bioavailability (F) of BHA was about 43% in the mice. In the mouse liver, BHA induced the expression of phase II genes including NQO-1, HO-1, γ-GCS, GST-pi and UGT 1A6, as well as some of the phase III transporter genes, such as MRP1 and Slco1b2. In addition, BHA activated distinct mitogen-activated protein kinases (MAPKs), c-Jun N-terminal kinase (JNK), extracellular signal-regulated protein kinase (ERK), as well as p38, suggesting that the MAPK pathways may play an important role in early signaling events leading to the regulation of gene expression including phase II drug metabolizing and some phase III drug transporter genes. This is the first study to demonstrate the in vivo pharmacokinetics of BHA, the in vivo activation of MAPK signaling proteins, as well as the in vivo induction of Phase II/III drug metabolizing enzymes/transporters in the mouse livers.

Differential Expression and Stability of Endogenous Nuclear Factor E2-related Factor 2 (Nrf2) by Natural Chemopreventive Compounds in HepG2 Human Hepatoma Cells

Jeong, Woo-Sik,Keum, Young-Sam,Chen, Chi,Jain, Mohit R.,Shen, Guoxiang,Kim, Jung-Hwan,Li, Wenge,Kong, Ah-Ng Tony Korean Society for Biochemistry and Molecular Biol 2005 Journal of biochemistry and molecular biology Vol.38 No.2

Nuclear factor-E2-related factor 2 (Nrf2) is known as a key regulator of ARE-mediated gene expression and the induction of Phase II detoxifying enzymes and antioxidant enzymes, which is also a common property of many chemopreventive agents. In the present study, we investigated the regulatory role of different chemopreventive agents including sulforaphane (SUL), allyl isothiocyanate (AITC), indole-3-carbinol (I3C), and parthenolide (PTL), in the expression and degradation of Nrf2 and the induction of the antioxidant enzyme HO-1. SUL strongly induced Nrf2 protein expression and ARE-mediated transcription activation, retarded degradation of Nrf2 through inhibiting Keap1, and thereby activating the transcriptional expression of HO-1. AITC was also a potent inducer of Nrf2 protein expression, ARE-reporter gene and HO-1 but had little effect on delaying the degradation of Nrf2 protein. Although PTL and I3C could induce ARE reporter gene expression and Nrf2 to some extent, they were not as potent as SUL and AITC. However, PTL dramatically induced the HO-1 expression, which was comparable to SUL, while I3C had no effect. In addition, when treated with SUL and PTL, inhibition of proteasome by MG132 did not cause additional accumulation of Nrf2, suggesting the involvement of other degradation mechanism(s) in the presence of these compounds such as SUL and PTL. In summary, the results of our current study indicated that different chemopreventive compounds have different regulatory properties on the accumulation and degradation of Nrf2 as well as the induction of cellular antioxidant enzyme HO-1.