Cancer cells display high rates of aerobic glycolysis, a phenomenon known historically as the Warburg effect. Lactate and pyruvate, the end products of glycolysis, are highly produced by cancer cells even in the presence of oxygen. Hypoxia-induced gene expression in cancer cells has been linked to malignant transformation. Here we provide evidence that lactate and pyruvate regulate hypoxia-inducible gene expression independently of hypoxia by stimulating the accumulation of hypoxia-inducible Factor 1␣ (HIF-1␣). In human gliomas and other cancer cell lines, the accumulation of HIF-1␣ protein under aerobic conditions requires the metabolism of glucose to pyruvate that prevents the aerobic degradation of HIF-1␣ protein, activates HIF-1 DNA binding activity, and enhances the expression of several HIF-1-activated genes including erythropoietin, vascular endothelial growth factor, glucose transporter 3, and aldolase A. Our findings support a novel role for pyruvate in metabolic signaling and suggest a mechanism by which high rates of aerobic glycolysis can promote the malignant transformation and survival of cancer cells.Cancer cell energy metabolism deviates significantly from that of normal tissues. Cancer cells maintain high aerobic glycolytic rates and produce high levels of lactate and pyruvate (1). This phenomenon was first described in cancer more than seven decades ago and is known historically as the Warburg effect (2, 3). Preferential reliance on glycolysis is correlated with disease progression in several types of cancers (4, 5), and the activities of hexokinase, phosphofructokinase, and pyruvate kinase are consistently and significantly increased in cancer cells (6 -8). Although oncogenes such as ras, src, and myc have been found to enhance aerobic glycolysis by increasing the expression of glucose transporters and glycolytic enzymes (8 -10), the relevance of the Warburg effect to cancer cell biology has remained obscure. Hypoxia is another common feature of many solid cancers and has been linked to malignant transformation, metastasis, and treatment resistance (11). The adaptation of cancer cells to hypoxia is mediated via hypoxia-inducible Factor 1 (HIF-1), 1 a key transcription factor that upregulates a series of genes involved in glycolytic energy metabolism, angiogenesis, cell survival, and erythropoiesis. Included among these genes are vascular endothelial growth factor (VEGF), erythropoietin (EPO), glucose transporters (GLUT), and several glycolytic enzymes (12, 13). HIF-1 is a heterodimer composed of two subunits, HIF-1␣ and HIF-1␤ (14), both of which are constitutively expressed in mammalian cells. The regulation of the HIF-1 complex is mainly dependent on the degradation of the HIF-1␣ subunit. Under nonhypoxic conditions, HIF-1␣ undergoes ubiquination and proteasomal degradation (15,16). This process involves the binding of the von Hippel-Lindau tumor suppressor protein to an oxygen-dependent degradation domain on the HIF-1␣ protein. A family of prolyl hydroxylase enzymes regulates the binding of...

Abstract-Diazoxide, a selective opener of the mitochondrial ATP-sensitive potassium channel, has been shown to elicit tolerance to ischemia in cardiac myocytes and in perfused heart. However, the mechanism of this cardioprotection is poorly understood. Because reactive oxygen species (ROS) are recognized as important intracellular signaling molecules and have been implicated in ischemic preconditioning, we examined diazoxide-induced ROS production in adult cardiomyocytes. Cells treated with 50 mol/L diazoxide showed a 173% increase in ROS production relative to baseline. 5-Hydroxydecanoate was found to attenuate the diazoxide-induced increase in ROS generation. The diazoxide-induced increase in ROS also was abrogated by the addition of either the antioxidant N-acetylcysteine (NAC) or N-mercaptopropionylglycine. We also examined the ability of NAC to block the protective effects of diazoxide in the perfused rat heart. After 20 minutes of global ischemia and 20 minutes of reflow, hearts perfused with 100 mol/L diazoxide before ischemia showed significantly improved postischemic contractile function relative to untreated hearts (84% versus 29% of initial left ventricular developed pressure, respectively). Hearts treated with diazoxide in the presence of 4 mmol/L NAC recovered 53% of initial left ventricular developed pressure, whereas hearts treated with NAC alone recovered 46% of preischemic function. Using 31 P NMR spectroscopy, we found that, similar to preconditioning, diazoxide significantly attenuated ischemia-induced intracellular acidification and enhanced postischemic recovery of phosphocreatine levels, both of which were blocked by cotreatment with NAC. These data suggest that the cardioprotective actions of diazoxide are mediated by generation of a pro-oxidant environment.

Both 10- and 30-mg/day doses of aripiprazole were superior to placebo in the acute treatment of adolescents with schizophrenia. Aripiprazole was generally well tolerated.

Objective:To evaluate the efficacy and tolerability of a oncemonthly intramuscular (IM) depot formulation of the dopamine partial agonist aripiprazole as maintenance treatment in adults meeting DSM-IV-TR schizophrenia criteria.

clinicaltrials.gov Identifier: NCT00110461.

This 24-week, open-label, Phase Ib, parallel-arm, multiple-dose trial assessed the pharmacokinetics, safety and tolerability of a once-monthly injection of aripiprazole (aripiprazole once-monthly) in 41 subjects with schizophrenia. The objective was to determine if aripiprazole plasma concentrations (at doses of 200, 300 and 400mg) were within the therapeutic range observed for the oral tablet (10-30 mg). Completion rates were 36.4% (n=4/11), 50.0% (n=8/16) and 71.4% (n=10/14) for the 200mg, 300 mg and 400mg groups, respectively. Patients were stabilized on oral aripiprazole (10mg/day) before the first injection and received oral aripiprazole (10mg/day) concomitantly with the first dose of aripiprazole once-monthly for 14 days. Administration of aripiprazole once-monthly at doses of 300 and 400mg provided sustained mean aripiprazole plasma concentrations comparable with the concentration range observed following multiple consecutive daily doses of oral aripiprazole. In contrast, plasma concentrations following administration of aripiprazole once-monthly at a dose of 200mg were below the therapeutic range and pharmacokinetic parameters were not proportional to the administered dose compared with the 300 mg and 400mg doses. Treatment with aripiprazole once-monthly, at any dose, did not result in any clinically meaningful changes from baseline in extrapyramidal symptom scales, clinical laboratory tests, vital signs, or electrocardiogram parameters. The most common treatment-emergent adverse events were vomiting (13.3%, 300 mg; 14.3%, 400mg), injection site pain (28.6%, 400mg), upper respiratory tract infection (10%, 200mg; 6.7% 300 mg; 14.3%, 400mg) and tremor (6.7%, 300 mg; 21.4%, 400mg). In conclusion, aripiprazole once-monthly at doses of 300 and 400mg is a viable formulation for treatment of adults with schizophrenia.

No abstract

Aripiprazole 10 mg/day and 30 mg/day were superior to placebo and generally well tolerated in pediatric subjects with bipolar I disorder up to 30 weeks. Despite the benefits of treatment, completion rates were low in all treatment arms.