piperidines and beta-lapachone

Chagas disease is caused by the hemoflagellate protozoa Trypanosoma cruzi and is one of the most important neglected tropical diseases, especially in Latin American countries, where there is an association between low-income populations and mortality. The nitroderivatives used in current chemotherapy are far from ideal and present severe limitations, justifying the continuous search for alternative drugs. Since the1990s, our group has been investigating the trypanocidal activity of natural naphthoquinones and their derivatives, and three naphthoimidazoles (N1, N2 and N3) derived from β-lapachone were found to be most effective in vitro. Analysis of their mechanism of action via cellular, molecular and proteomic approaches indicates that the parasite mitochondrion contains one of the primary targets of these compounds, trypanothione synthetase (involved in trypanothione production), which is overexpressed after treatment with these compounds. Here, we further evaluated the participation of the mitochondria and reactive oxygen species (ROS) in the anti-T. cruzi action of naphthoimidazoles. Preincubation of epimastigotes and trypomastigotes with antioxidants (α-tocopherol and urate) strongly protected the parasites from the trypanocidal effect of naphthoimidazoles, decreasing the ROS levels produced and reverting the mitochondrial swelling phenotype. The addition of pro-oxidants (menadione and H

Topics: Animals; Chagas Disease; Humans; Hydrogen Peroxide; Imidazoles; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Swelling; Naphthoquinones; Organophosphorus Compounds; Piperidines; Proteomics; Reactive Oxygen Species; Trypanocidal Agents; Trypanosoma cruzi

Nicotinamide phosphoribosyltransferase (NAMPT) inhibitors (e.g., FK866) target the most active pathway of NAD(+) synthesis in tumor cells, but lack tumor-selectivity for use as a single agent. Reducing NAD(+) pools by inhibiting NAMPT primed pancreatic ductal adenocarcinoma (PDA) cells for poly(ADP ribose) polymerase (PARP1)-dependent cell death induced by the targeted cancer therapeutic, β-lapachone (β-lap, ARQ761), independent of poly(ADP ribose) (PAR) accumulation. β-Lap is bioactivated by NADPH:quinone oxidoreductase 1 (NQO1) in a futile redox cycle that consumes oxygen and generates high levels of reactive oxygen species (ROS) that cause extensive DNA damage and rapid PARP1-mediated NAD(+) consumption. Synergy with FK866+β-lap was tumor-selective, only occurring in NQO1-overexpressing cancer cells, which is noted in a majority (∼85%) of PDA cases. This treatment strategy simultaneously decreases NAD(+) synthesis while increasing NAD(+) consumption, reducing required doses and treatment times for both drugs and increasing potency. These complementary mechanisms caused profound NAD(P)(+) depletion and inhibited glycolysis, driving down adenosine triphosphate levels and preventing recovery normally observed with either agent alone. Cancer cells died through an ROS-induced, μ-calpain-mediated programmed cell death process that kills independent of caspase activation and is not driven by PAR accumulation, which we call NAD(+)-Keresis. Non-overlapping specificities of FK866 for PDA tumors that rely heavily on NAMPT-catalyzed NAD(+) synthesis and β-lap for cancer cells with elevated NQO1 levels affords high tumor-selectivity. The concept of reducing NAD(+) pools in cancer cells to sensitize them to ROS-mediated cell death by β-lap is a novel strategy with potential application for pancreatic and other types of NQO1+ solid tumors.

Topics: Acrylamides; Cell Death; Cell Line, Tumor; DNA Breaks, Double-Stranded; Drug Synergism; Energy Metabolism; Glycolysis; Humans; NAD(P)H Dehydrogenase (Quinone); Naphthoquinones; Nicotinamide Phosphoribosyltransferase; Pancreatic Neoplasms; Piperidines; Poly Adenosine Diphosphate Ribose; Reactive Oxygen Species

Pancreatic cancer (PC) is one of the most lethal human malignancies and a major health problem. Patients diagnosed with PC and treated with conventional approaches have an overall 5-year survival rate of less than 5%. Novel strategies are needed to treat this disease. Herein, we propose a combinatorial strategy that targets two unrelated metabolic enzymes overexpressed in PC cells:. quinone oxidoreductase-1 (NQO1) and nicotinamide phosphoribosyl transferase (NAMPT) using β-lapachone (BL) and APO866, respectively. We show that BL tremendously enhances the antitumor activity of APO866 on various PC cell lines without affecting normal cells, in a PARP-1 dependent manner. The chemopotentiation of APO866 with BL was characterized by the following: (i) nicotinamide adenine dinucleotide (NAD) depletion; (ii) catalase (CAT) degradation; (iii) excessive H2O2 production; (iv) dramatic drop of mitochondrial membrane potential (MMP); and finally (v) autophagic-associated cell death. H2O2 production, loss of MMP and cell death (but not NAD depletion) were abrogated by exogenous supplementation with CAT or pharmacological or genetic inhibition of PARP-1. Our data demonstrates that the combination of a non-lethal dose of BL and low dose of APO866 optimizes significantly cell death on various PC lines over both compounds given separately and open new and promising combination in PC therapy.

Topics: Acrylamides; Cell Death; Cell Line; Cell Line, Tumor; Humans; Immunoblotting; Membrane Potential, Mitochondrial; Naphthoquinones; Pancreatic Neoplasms; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Reactive Oxygen Species