Anti-Inflammatory, Antiproliferative, and Cytoprotective Activity of NO Chimera Nitrates of Use in Cancer Chemoprevention

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown promise in colorectal cancer (CRC), but they are compromised by gastrotoxicity. NO-NSAIDs are hybrid nitrates conjugated to an NSAID designed to exploit the gastroprotective properties of NO bioactivity. The NO chimera ethyl 2-((2,3-bis(nitrooxy)propyl)disulfanyl)benzoate (GT-094), a novel nitrate containing an NSAID and disulfide pharmacophores, is effective in vivo in rat models of CRC and is a lead compound for design of agents of use in CRC. Preferred chemopreventive agents possess 1) antiproliferative and 2) anti-inflammatory actions and 3) the ability to induce cytoprotective phase 2 enzymes. To determine the contribution of each pharmacophore to the biological activity of GT-094, these three biological activities were studied in vitro in compounds that deconstructed the structural elements of the lead GT-094. The anti-inflammatory and antiproliferative actions of GT-094 in vivo were recapitulated in vitro, and GT-094 was seen to induce phase 2 enzymes via the antioxidant responsive element. In the variety of colon, macrophage-like, and liver cell lines studied, the evidence from structure-activity relationships was that the disulfide structural element of GT-094 is the dominant contributor in vitro to the anti-inflammatory activity, antiproliferation, and enzyme induction. The results provide a direction for lead compound refinement. The evidence for a contribution from the NO mimetic activity of nitrates in vitro was equivocal, and combinations of nitrates with acetylsalicylic acid were inactive.Colorectal cancer (CRC) is a leading cause of death, providing impetus for discovery of new chemopreventive agents. Chemoprevention strategies for CRC have targeted antiproliferative and anti-inflammatory actions on colonocytes containing populations subject to carcinogen-induced DNA damage. Although, the exact mechanisms of colon carcinogenesis remain to be revealed, there are clear biomarkers that correlate with drug intervention and tumorigenesis, in particular biomarkers of inflammation and of proliferation.Aberrant crypt foci (ACF) are seen as an early precursor stage to adenomas and cancer, which facilitate early diagnosis. The ACF is a monoclonal structure that arises from mutations within a single crypt stem cell, thought to result from a single mutational event within an isolated colon crypt. ACF are strongly linked to colon cancer risk, and in animal models, such as the murine azoxymethane (AOM) carcinogen model, a good correlation between ACF number and tumorigenesis has been reported for a variety of chemopreventive agents (Corpet and Taché, 2002 ABBREVIATIONS: CRC, colorectal cancer; ACF, aberrant crypt foci; AOM, azoxymethane; iNOS, inducible nitric-oxide synthase; NSAID nonsteroidal anti-inflammatory drug; ASA, aspirin; GI, gastrointestinal; NO-NSAID, NO-donating nonsteroidal anti-inflammatory drug; BECS, 1,2-bis-(2-ethoxycarbonylphenyl)sulfane; FBS, fetal bovine serum; DMEM, Dulbecco's modified Eagle's medium; ARE, antioxidant respon...

The Role of Cyclic Nucleotide Signaling Pathways in Cancer: Targets for Prevention and Treatment

“…Among these are the NO donors and sGC activators, such as sodium nitroprusside (SNP), and peptide activators of pGC, such as guanylin, uroguanylin, and heat-stabile enterotoxin (ST h ). While the potential efficacy of the NO donors (e.g., NO-NSAIDs) and sGC activators for cancer chemoprevention and chemotherapy has been well documented [64,113,114,115,116,117], their potential for toxicity has precluded their development for either chemoprevention or chemotherapy [118]. In addition, it is unclear if the effects of all NO donors are related to the release of NO, as alternate mechanisms such as increased membrane permeability may be involved [117,119].…”

GT-094, a NO-NSAID, Inhibits Colon Cancer Cell Growth by Activation of a Reactive Oxygen Species-MicroRNA-27a: ZBTB10-Specificity Protein Pathway

“…Ethyl 2-((2,3-bis(nitrooxy)propyl)disulfanyl)benzoate (GT-094) (25, 26) is a novel NO chimera containing an NSAID and NO moieties and also a disulfide pharmacophore that in itself exhibits cancer chemopreventive activity (28). GT-094 significantly decreases aberrant crypt foci, proliferation and inducible NO synthase (iNOS) levels in the azoxymethane-induced rat colon cancer (25) and decreases proliferation and arrests Caco-2 colon cancer cells in G2/M phase of the cell cycle (25, 26).…”

Characterization of New Organic Nitrate Hybrid Drugs Covalently Bound to Valsartan and Cilostazol

“…There are several reports in the literature on nitrate hybrid molecules: nicorandil, a potassium channel opener with nitrate function [10,11]; 2NTX-99, a thromboxane synthase inhibitor and thromboxane receptor antagonist and NO-releasing group [12]; GT-094, a nonsteroidal anti-inflammatory drug with NO function [13]; the antifungal drug ketoconazole with a diazen-1-ium-1,2-diolate or an organic nitrate moiety [14]; NO-donor-tacrine hybrids as hepatoprotective anti-Alzheimer drug candidates [15]; the NicOx compound nitroaspirin, reviewed in Gresele and Momi [16]; NO-releasing celecoxib analogs, inhibitors of inducible cyclooxygenase [17]; a vitamin E analog with NO donor function [18]. Probably we could not list all examples that have been published during the last few years but our list provides an overview of the diversity of NO hybrids.…”