ABSTRACT:Comprehensive mechanistic studies suggest that oltipraz exerts cancer chemopreventive effects through the induction of glutathione S-transferase (GST). Previously, we have shown that the activation of CCAAT/enhancer binding protein-␤ (C/EBP␤), promoted by oltipraz, contributes to the transcriptional induction of the GSTA2 gene. Studies also indicated that exposure of animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) with an increase in Nrf2's antioxidant response element (ARE) binding activity. Given the previous reports that C/EBP␤ activation contributes to oltipraz's induction of the GSTA2 gene and that Nrf2 activation by oltipraz was variable depending on the concentrations, this study investigated whether the major oxidized metabolites of oltipraz induce GSTA2 through the activation of C/EBP␤ and/or Nrf2. Immunoblot analysis revealed that M1 Oltipraz [4-methyl-5-(2-pyrazinyl)-1,2-dithiol-3-thione] has been studied as a chemopreventive agent for malignancies, such as liver and colorectal cancer (Rao et al., 1993;Kensler, 1997). Comprehensive mechanistic studies indicate that oltipraz exerts cancer chemopreventive effects through the induction of glutathione S-transferases (GSTs) (Bolton et al., 1993;Kensler, 1997). GST induction also accounts for the cytoprotective effect of oltipraz against toxicantinduced injury (Jaitovitch-Groisman et al., 2000;Nelson et al., 2002). A phase IIa randomized chemoprevention trial of oltipraz in residents of Qidong, China, showed that oltipraz might be clinically active as a chemopreventive agent. In the human studies, oltipraz dosage regimens with higher doses and a long-dosing interval seemed to be more efficacious in preventing cancer, as supported by a significant decline in the levels of aflatoxin-albumin adduct in the individuals receiving a higher dose of oltipraz (500 mg/week) (Jacobson et al., 1997;Jackson and Groopman, 1999;Wang et al., 1999).Exposure of experimental animals to oltipraz triggers nuclear accumulation of NF-E2-related factor-2 (Nrf2) Iida et al., 2004) and enhances Nrf2's antioxidant response element (ARE) binding activity (Pietsch et al., 2003). Diminished expression of phase II enzyme genes by oltipraz in the Nrf2 Ϫ/Ϫ mice supports the role of Nrf2 activation in its cancer chemopreventive effects Ramos-Gomez et al., 2001). Molecular signals activated by oxidative stress stimulate translocation of Nrf2 to the nucleus, where it binds and activates the AREs located in the promoter regions of phase II enzyme genes (Moinova and Mulcahy, 1998;Venugopal and Jaiswal, 1998;Huang et al., 2000).Studies from this laboratory showed that oltipraz at clinically relevant concentrations marginally increased the band intensity of Nrf2 ARE binding and thus weakly enhanced the accumulation of Nrf2 in the nucleus. Our results suggested that GSTA2 induction by oltipraz might be mediated by the activation of other transcriptional Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.doi:10...

Chemokine receptor 2 (CCR2) is a G-protein coupled receptor (GPCR) and a crucial target for various inflammatory and autoimmune diseases. The structure based antagonists design for many GPCRs, including CCR2, is restricted by the lack of an experimental three dimensional structure. Homology modeling is widely used for the study of GPCR-ligand binding. Since there is substantial diversity for the ligand binding pocket and binding modes among GPCRs, the receptor-ligand binding mode predictions should be derived from homology modeling with supported ligand information. Thus, we modeled the binding of our proprietary CCR2 antagonist using ligand supported homology modeling followed by consensus scoring the docking evaluation based on all modeled binding sites. The protein-ligand model was then validated by visual inspection of receptor-ligand interaction for consistency of published site-directed mutagenesis data and virtual screening a decoy compound database. This model was able to successfully identify active compounds within the decoy database. Finally, additional hit compounds were identified through a docking-based virtual screening of a commercial database, followed by a biological assay to validate CCR2 inhibitory activity. Thus, this procedure can be employed to screen a large database of compounds to identify new CCR2 antagonists.

Anti-cancer agents delivered to cancer cells often show multi-drug resistance (MDR) due to expulsion of the agents. One way to address this problem is to increase the accumulation of anti-cancer agents in cells via amino acid transporters. Thus, val-lapatinib and tyr-lapatinib were newly synthesized by adding valine and tyrosine moieties, respectively, to the parent anti-cancer agent lapatinib without stability issues in rat plasma. Val-lapatinib and tyr-lapatinib showed enhanced anti-cancer effects versus the parent lapatinib in various cancer cell lines, including human breast cancer cells (MDA-MB-231, MCF7) and lung cancer cells (A549), but not in non-cancerous MDCK-II cells. A glutamine uptake study revealed that both val-lapatinib and tyr-lapatinib, but not the parent lapatinib, inhibited glutamine transport in MDA-MB-231 and MCF7 cells, suggesting the involvement of amino acid transporters. In conclusion, val-lapatinib and tyr-lapatinib have enhanced anti-cancer effects, likely due to an increased uptake of the agents into cancer cells via amino acid transporters. The present data suggest that amino acid transporters may be an effective drug delivery target to increase the uptake of anti-cancer agents, leading to one method of overcoming MDR in cancer cells.

Abstract11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) is a key enzyme that catalyzes the intracellular conversion of cortisone to physiologically active cortisol. Although 11βHSD1 has been implicated in numerous metabolic syndromes, such as obesity and diabetes, the functional roles of 11βHSD1 during progression of nonalcoholic steatohepatitis (NASH) and consequent fibrosis have not been fully elucidated. We found that pharmacological and genetic inhibition of 11βHSD1 resulted in reprogramming of hepatic stellate cell (HSC) activation via inhibition of p-SMAD3, α-SMA, Snail, and Col1A1 in a fibrotic environment and in multicellular hepatic spheroids (MCHSs). We also determined that 11βHSD1 contributes to the maintenance of NF-κB signaling through modulation of TNF, TLR7, ITGB3, and TWIST, as well as regulating PPARα signaling and extracellular matrix accumulation in activated HSCs during advanced fibrogenesis in MCHSs. Of great interest, the 11βHSD1 inhibitor J2H-1702 significantly attenuated hepatic lipid accumulation and ameliorated liver fibrosis in diet- and toxicity-induced NASH mouse models. Together, our data indicate that J2H-1702 is a promising new clinical candidate for the treatment of NASH.

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