Influence of high glucose state on bromopyruvate-induced cytotoxity by human colon cancer cell lines.

BACKGROUND: Attention must be paid to chemotherapy for cancer patients in a hyperglycemia state. It is difficult for chemotherapy to cure cancer in patients in a hyperglycemia state. This study was carried out to determine the change in cell viability after treatment with bromopyruvate, which is an alkylating drug with anti-tumor activity, in a high glucose condition. METHODS: The function of l-lactate and bromopyruvate transport was studied using human colon cancer cell lines (LoVo and HT-29) and radiolabeled l-lactate and bromopyruvate. Cell viability was monitored by the trypan blue exclusion assay. The expression level of human monocarboxylate transporter 1 (hMCT1) was evaluated by Western blot analysis. RESULTS: Bromopyruvate-induced cell death was suppressed by a high glucose condition. l-Lactate and bromopyruvate uptake were suppressed by a high glucose condition. hMCT1 as a bromopyruvate carrier was functionally expressed in the cells. However, the expression of hMCT1 was suppressed by a high glucose state. CONCLUSIONS: Down-regulation of hMCT1 by a high glucose state is one of the possibilities of the bromopyruvate resistance. We should pay scrupulous attention to cancer chemotherapy for patients who have developed diabetes.

Safety and outcome of treatment of metastatic melanoma using 3-bromopyruvate: a concise literature review and case study.

3-Bromopyruvate (3BP) is a new, promising anticancer alkylating agent with several notable functions. In addition to inhibiting key glycolysis enzymes including hexokinase II and lactate dehydrogenase (LDH), 3BP also selectively inhibits mitochondrial oxidative phosphorylation, angiogenesis, and energy production in cancer cells. Moreover, 3BP induces hydrogen peroxide generation in cancer cells (oxidative stress effect) and competes with the LDH substrates pyruvate and lactate. There is only one published human clinical study showing that 3BP was effective in treating fibrolamellar hepatocellular carcinoma. LDH is a good measure for tumor evaluation and predicts the outcome of treatment better than the presence of a residual tumor mass. According to the Warburg effect, LDH is responsible for lactate synthesis, which facilitates cancer cell survival, progression, aggressiveness, metastasis, and angiogenesis. Lactate produced through LDH activity fuels aerobic cell populations inside tumors via metabolic symbiosis. In melanoma, the most deadly skin cancer, 3BP induced necrotic cell death in sensitive cells, whereas high glutathione (GSH) content made other melanoma cells resistant to 3BP. Concurrent use of a GSH depletor with 3BP killed resistant melanoma cells. Survival of melanoma patients was inversely associated with high serum LDH levels, which was reported to be highly predictive of melanoma treatment in randomized clinical trials. Here, we report a 28-year-old man presented with stage IV metastatic melanoma affecting the back, left pleura, and lung. The disease caused total destruction of the left lung and a high serum LDH level (4,283 U/L). After ethics committee approval and written patient consent, the patient received 3BP intravenous infusions (1-2.2 mg/kg), but the anticancer effect was minimal as indicated by a high serum LDH level. This may have been due to high tumor GSH content. On combining oral paracetamol, which depletes tumor GSH, with 3BP treatment, serum LDH level dropped maximally. Although a slow intravenous infusion of 3BP appeared to have minimal cytotoxicity, its anticancer efficacy via this delivery method was low. This was possibly due to high tumor GSH content, which was increased after concurrent use of the GSH depletor paracetamol. If the anticancer effectiveness of 3BP is less than expected, the combination with paracetamol may be needed to sensitize cancer cells to 3BP-induced effects.

Aerosolized 3-bromopyruvate inhibits lung tumorigenesis without causing liver toxicity.

3-Bromopyruvate, an alkylating agent and a well-known inhibitor of energy metabolism, has been proposed as a specific anticancer agent. However, the chemopreventive effect of 3-bromopyruvate in lung tumorigenesis has not been tested. In this study, we investigated the chemopreventive activity of 3-bromopyruvate in a mouse lung tumor model. Benzo(a)pyrene was used to induce lung tumors, and 3-bromopyruvate was administered by oral gavage to female A/J mice. We found that 3-bromopyruvate significantly decreased tumor multiplicity and tumor load by 58% and 83%, respectively, at a dose of 20 mg/kg body weight by gavage. Due to the known liver toxicity of 3-bromopyruvate in animal models given large doses of 3-bromopyruvate, confirmed in this study, we decided to test the chemopreventive activity of aerosolized 3-bromopyruvate in the same lung tumor model. As expected, aerosolized 3-bromopyruvate similarly significantly decreased tumor multiplicity and tumor load by 49% and 80%, respectively, at a dose of 10 mg/mL by inhalation. Interestingly, the efficacy of aerosolized 3-bromopyruvate did not accompany any liver toxicity indicating that it is a safer route of administering this compound. Treatment with 3-bromopyruvate increased immunohistochemical staining for cleaved caspase-3, suggesting that the lung tumor inhibitory effects of 3-bromopyruvate were through induction of apoptosis. 3-Bromopyruvate also dissociated hexokinase II from mitochondria, reduced hexokinase activity, and blocked energy metabolism in cancer cells, finally triggered cancer cell death and induced apoptosis through caspase-3, and PARP in human lung cancer cell line. The ability of 3-bromopyruvate to inhibit mouse lung tumorigenesis, in part through induction of apoptosis, merits further investigation of this compound as a chemopreventive agent for human lung cancer.

Preliminary safety and biological efficacy studies of ethyl pyruvate in normal mature horses.

REASONS FOR PERFORMING THE STUDY: Endotoxaemia causes substantial morbidity and mortality in horses with colic and sepsis. Ethyl pyruvate is a novel anti-inflammatory medication that improved survival in preclinical models of severe sepsis endotoxaemia and intestinal ischaemia and reperfusion in rodents, swine, sheep and dogs and may be a useful medication in horses. HYPOTHESIS: Ethyl pyruvate has no adverse effects in normal horses and is biologically active based on suppression of proinflammatory gene expression in endotoxin stimulated whole blood, in vitro. METHODS: Physical and neurological examinations, behaviour scores, electrocardiograms and clinicopathological tests were performed on 5 normal healthy horses receiving 4 different doses of ethyl pyruvate. Doses included 0, 50, 100 and 150 mg/kg bwt administered in a randomised crossover design with a 2 week washout period between doses. Biological efficacy was assessed by stimulating whole blood with endotoxin from the horses that received ethyl pyruvate prior to and 1 and 6 h after drug infusion. Gene expression for TNFα, IL-1ß and IL-6 was assessed. RESULTS: There were no effects of drug or dose (0, 50, 100 or 150 mg/kg bwt) on any of the physical or neurological examination, behaviour factors, electrocardiogram or clinical pathological results collected from any of the horses. All parameters measured remained within the normal reference range. There was a significant reduction in TNFα, IL-1ß and IL-6 gene expression in endotoxin stimulated whole blood from horses 6 h after receiving 150 mg/kg bwt ethyl pyruvate. There were no detectable effects on gene expression of any of the other doses of ethyl pyruvate tested. CONCLUSION: We were unable to detect any detrimental effects of ethyl pyruvate administration in normal horses. Ethyl pyruvate significantly decreased proinflammatory gene expression in endotoxin stimulated blood 6 h after drug administration. CLINICAL RELEVANCE: Ethyl pyruvate may be a safe, effective medication in endotoxaemic horses.

Can we predict the effects of NF-kappaB inhibition in sepsis? Studies with parthenolide and ethyl pyruvate.

BACKGROUND: Based partially on encouraging findings from preclinical models, interest has grown in therapeutic inhibition of NF-kappaB to limit inflammatory injury during sepsis. However, NF-kappaB also regulates protective responses, and predicting the net survival effects of such inhibition may be difficult. OBJECTIVES: To highlight the caution necessary with this therapeutic approach, we review our investigations in a mouse sepsis model with parthenolide and ethyl pyruvate, two NF-kappaB inhibitors proposed for clinical study. RESULTS: Consistent with published studies, parthenolide decreased NF-kappaB binding activity and inflammatory cytokine release from lipopolysaccharide (LPS) stimulated RAW 264.7 cells in vitro. In LPS-challenged mice (C57BL/6J), however, while both agents decreased lung and kidney NF-kappaB binding activity and plasma cytokines early (1-3 h), these measures were increased later (6-12 h) in patterns differing significantly over time. Furthermore, despite studying several doses of parthenolide (0.25-4.0 mg/kg) and ethyl pyruvate (0.1-100 mg/kg), each produced small but consistent decreases in survival which overall were significant (p < or = 0.04 for each agent). CONCLUSION: While NF-kappaB inhibitors hold promise for inflammatory conditions such as sepsis, caution is necessary. Clear understanding of the net effects of NF-kappaB inhibitors on outcome will be necessary before such agents are used clinically.

Intraarterial therapy with a new potent inhibitor of tumor metabolism (3-bromopyruvate): identification of therapeutic dose and method of injection in an animal model of liver cancer.

PURPOSE: A potent new adenosine triphosphate inhibitor--3-bromopyruvate (3-BrPA)--has been shown to have antitumor effects when injected intraarterially in the hepatic artery of rabbits with VX-2 tumors. The authors performed a stepwise study in rabbits to determine the therapeutic dose and method of delivery of 3-BrPA. MATERIALS AND METHODS: White New Zealand rabbits with VX-2 tumors were used for this study. Eight animals were examined to establish the maximum tolerated dose (2.5 or 5.0 mmol/L of 25-mL 3-BrPA) as a single bolus injection. The 2.5 mmol/L dose was then used to compare three methods of delivery: injection of one bolus, two 12.5-mL serial bolus injections administered 1 hour apart, and continuous infusion of 25 mL for 1 hour. Finally, dose-response analysis was performed by using 10 groups of three animals each, with 1-hour intraarterial infusions of 3-BrPA (25 mL) at incremental doses of 0.25 mmol/L (range, 0.5-2.5 mmol/L) with phosphate buffered saline used for control animals. All animals were sacrificed at 48 hours, and histopathologic analysis was performed. chi2 statistics were used to analyze the data. RESULTS: The maximum tolerated dose of 3-BrPA was 2.5 mmol/L; however, it caused substantial peripheral liver necrosis. These effects were minimized when 3-BrPA was infused over 1 hour. Complete tumor necrosis was identified in all samples with at least 2.0 mmol/L of 3-BrPA. The 1.75 mmol/L concentration was identified as therapeutic because it caused complete tumor apoptosis and minimal toxicity (P < .001). CONCLUSIONS: The results identified both the therapeutic dose (1.75 mmol/L) and the method of infusion (1 hour intraarterial infusion) of 3-BrPA. This potent new treatment may prove to be an effective way of treating liver cancer and may become part of a new class of anticancer drugs based on the inhibition of tumor metabolism.

Novel therapy for liver cancer: direct intraarterial injection of a potent inhibitor of ATP production.

Most types of cancer are difficult to eradicate and some, like liver carcinomas, are almost always fatal. Significantly, we report here that direct intraarterial delivery of 3-bromopyruvate (3-BrPA), a potent inhibitorof cell ATP production, to liver-implanted rabbit tumors, inflicts a rapid, lethal blow to most cancer cells therein. Moreover, systemic delivery of 3-BrPA suppresses "metastatic" tumors that arise in the lungs. In both cases, there is no apparent harm to other organs or to the animals. Thus, intraarterial delivery of agents like 3-BrPA directly to the site of the primary tumor, followed by systemic delivery only when necessary, may represent a powerful new strategy for arresting the growth of liver and other cancers while minimizing toxic side effects.

Sodium pyruvate infusions in patients with alcoholic liver disease. Preliminary report.

Pyruvate has been shown to benefit cellular energy metabolism and to reduce free radical formation. Concerning gastrointestinal side effects of orally administered sodium pyruvate, in this pilot study we investigated the therapeutic effectiveness of sodium pyruvate infusions in patients with alcoholic liver disease (ALD). Fifteen patients with ALD received sodium pyruvate infusions for: (1) 10 days (54-86.4 g pyruvate daily, 150-180 mg/min., 6-8 h); and (2) 15 days (50-54 g daily, 100 mg/min., 6 h). Sodium pyruvate treatment resulted in significantly decreased serum AST (p<0.03), ALT (p<0.03), AP (p<0.004), GGT (p<0.05), and total bilirubin (p<0.04). Improvement of liver function was also evident from the significantly decreased Combined Clinical and Laboratory Index (from 6.50+/-0.71, to 3.92+/-0.84, p<0.001), and Liver Damage Score (from 3.83+/-0.71 to 2.75+/-0.58, p<0.01). The two therapy schedules used showed similar results. Unchanged serum pyruvate, lactate, and glucose confirmed the good utilization of pyruvate. Tolerance of sodium pyruvate treatment was very good in 26.09% and good in 68.94% of the observations. Our results showed good therapeutic effectiveness and good tolerance of sodium pyruvate infusions in patients with ALD. This is possibly due to the rapid gain of ATP and GTP, required to redress defective cells, and to antioxidant action of pyruvate.

Effect of different buffers on the biocompatibility of CAPD solutions.

Commercially available solutions for continuous ambulatory peritoneal dialysis (CAPD) affect the viability and function of the cells in the peritoneal cavity. The low biocompatibility of the solutions may be caused by a low pH, hyperosmolality, high glucose content, and lack of potassium, glutamine, and other components essential for normal cellular functions. The nature of the buffer employed is also important for the cytotoxicity of the solutions. Lactate, the most frequently used buffer, has been shown to inhibit cellular functions important for the peritoneal defense system including phagocytosis, bacterial killing, and secretion of cytokines. It is generally believed that the cytotoxicity of lactate is caused by lowering of intracellular pH and impairment of metabolism due to changed redox potentials. However, the cytotoxicity of lactate is highly dependent upon the pH of the solutions, indicating that passive or active diffusion across the cell membrane is determining the effects of lactate. Bicarbonate has been heavily advocated as an alternative buffer because it is the most important naturally occurring buffer in plasma and it enables a pH of approximately 7.4 in the solutions. However, due to sedimentation of calcium carbonate (CaCO3) and production of toxic glucose metabolites it is difficult to prepare and store bicarbonate-based solutions. Moreover, investigations have revealed that even bicarbonate-based solutions are not optimal regarding biocompatibility, presumably due to a paradoxical intracellular acidification caused by influx of carbon dioxide (CO2). More recently, the effect of other buffers such as pyruvate and histidine have been examined. Especially pyruvate is a promising new buffer candidate.