Cytoskeleton disruption by the metabolic inhibitor 3-bromopyruvate: implications in cancer therapy.

The small molecule 3-bromopyruvate (3BP), is an anticancer molecule that acts by hindering glycolysis and mitochondrial function leading to energy depletion and consequently, to cell death. In this work we have focused on understanding how the glycolytic inhibition affects cancer cell structural features. We showed that 3BP leads to a drastic decrease in the levels of ß-actin and α-tubulin followed by disorganization and shrinkage of the cytoskeleton in breast cancer cells. 3BP inhibits cell migration and colony formation independently of the activity of metalloproteinases. To disclose if these structural alterations occurred prior to 3BP toxic effect, non-toxic concentrations of 3BP were used and we could observe that 3BP was able to inhibit energy production and induce loss of ß-actin and α-tubulin proteins. This was accompanied with alterations in cytoskeleton organization and an increase in E-cadherin levels which may indicate a decrease in cancer cells aggressiveness. In this study we demonstrate that 3BP glycolytic inhibition of breast cancer cells is accompanied by cytoskeleton disruption and consequently loss of migration ability, suggesting that 3BP can potentially be explored for metastatic breast cancer therapy.

Comparative pharmacology and toxicology of tramadol and tapentadol.

Moderate-to-severe pain represents a heavy burden in patients' quality of life, and ultimately in the society and in healthcare costs. The aim of this review was to summarize data on tramadol and tapentadol adverse effects, toxicity, potential advantages and limitations according to the context of clinical use. We compared data on the pharmacological and toxicological profiles of tramadol and tapentadol, after an extensive literature search in the US National Library of Medicine (PubMed). Tramadol is a prodrug that acts through noradrenaline and serotonin reuptake inhibition, with a weak opioid component added by its metabolite O-desmethyltramadol. Tapentadol does not require metabolic activation and acts mainly through noradrenaline reuptake inhibition and has a strong opioid activity. Such features confer tapentadol potential advantages, namely lower serotonergic, dependence and abuse potential, more linear pharmacokinetics, greater gastrointestinal tolerability and applicability in the treatment of chronic and neuropathic pain. Although more studies are needed to provide clear guidance on the opioid of choice, tapentadol shows some advantages, as it does not require CYP450 system activation and has minimal serotonergic effects. In addition, it leads to less side effects and lower abuse liability. However, in vivo and in vitro studies have shown that tramadol and tapentadol cause similar toxicological damage. In this context, it is important to underline that the choice of opioid should be individually balanced and a tailored decision, based on previous experience and on the patient's profile, type of pain and context of treatment. SIGNIFICANCE: This review underlines the need for a careful prescription of tramadol and tapentadol. Although both are widely prescribed synthetic opioid analgesics, their toxic effects and potential dependence are not completely understood yet. In particular, concerning tapentadol, further research is needed to better assess its toxic effects.

The anticancer agent 3-bromopyruvate: a simple but powerful molecule taken from the lab to the bedside.

At the beginning of the twenty-first century, 3-bromopyruvate (3BP), a simple alkylating chemical compound was presented to the scientific community as a potent anticancer agent, able to cause rapid toxicity to cancer cells without bystander effects on normal tissues. The altered metabolism of cancers, an essential hallmark for their progression, also became their Achilles heel by facilitating 3BP's selective entry and specific targeting. Treatment with 3BP has been administered in several cancer type models both in vitro and in vivo, either alone or in combination with other anticancer therapeutic approaches. These studies clearly demonstrate 3BP's broad action against multiple cancer types. Clinical trials using 3BP are needed to further support its anticancer efficacy against multiple cancer types thus making it available to more than 30 million patients living with cancer worldwide. This review discusses current knowledge about 3BP related to cancer and discusses also the possibility of its use in future clinical applications as it relates to safety and treatment issues.

Clinicopathologic significance of BubR1 and Mad2 overexpression in oral cancer.

OBJECTIVES: BubR1 and Mad2 are central components of the mitotic checkpoint complex that inhibits anaphase onset until all chromosomes are correctly aligned at the metaphase plate. We propose to analyse the combined expression of BubR1 and Mad2 and assess its significance to oral squamous cell carcinoma (OSCC) diagnosis and prognosis. MATERIALS AND METHODS: BubR1 and Mad2 expression was assessed by real-time PCR in OSCC cell lines and in normal human oral keratinocytes, and by immunohistochemistry in 65 patients with OSCC. The results were compared regarding clinicopathological parameters, proliferative activity and survival. RESULTS: BubR1 and Mad2 transcripts were overexpressed in OSCC cell lines which also exhibited attenuated spindle assembly checkpoint activity. BubR1 and Mad2 were also overexpressed in patients with OSCC. BubR1 expression was associated with advanced stages and larger tumour size in univariate analysis, and with shorter overall survival both in univariate and multivariate analysis. Mad2 overexpression was associated with that of BubR1 and, importantly, high expression of Mad2 and BubR1 was associated with increased cellular proliferation. CONCLUSION: Our data propose a role for BubR1 and Mad2 in OSCC cellular proliferation, progression and prognosis.

Monocarboxylate transporters as targets and mediators in cancer therapy response.

Monocarboxylate transporters (MCTs) belong to a family of transporters, encoded by the SLC16 gene family, which is presently composed by 14 members, but only MCT1 to 4 have been biochemically characterized. They have important functions in healthy tissues, being involved in the transmembrane transport of lactic acid and other monocarboxylic acids in human cells. One of the recently recognized hallmarks of cancer is altered metabolism, with high rates of glucose consumption and consequent lactate production. To maintain this metabolic phenotype, cancer cells upregulate a series of plasma membrane proteins, including MCTs. MCT1 and MCT4, in particular, play a dual role in the maintenance of the metabolic phenotype of tumour cells. On one hand, they facilitate the efflux of lactate and, on the other hand, they contribute to the preservation of the intracellular pH, by co-transporting a proton. Thus, MCTs are attractive targets in cancer therapy, especially in cancers with a hyper-glycolytic and acid-resistant phenotype. Recent evidence demonstrates that MCTs are involved in cancer cell uptake of chemotherapeutic agents, including 3-bromopyruvate. In this way MCTs can act as "Trojan horses", as their elevated expression in cancer cells can mediate the entry of this chemotherapeutic agent into the cells and selectively kill cancer cells. As a result, MCTs will be mediators of chemotherapeutic response, and their expression can be used as a molecular marker to predict response to chemotherapy.

Isolation and characterization of Kluyveromyces marxianus mutants deficient in malate transport.

In malic acid-grown cells of the strains ATCC 10022 and KMS3 of Kluyveromyces marxianus the transport of malic acid occurred by a malate-proton symport, which accepted L-malic, D-malic, succinic and fumaric acids, but not tartaric, malonic or maleic acids. The system was inducible and subjected to glucose repression. Mutants of the strain KMS3, unable to grow in a medium with malic acid, were isolated and checked for their capacity to utilize several carbon sources and to transport dicarboxylic acids by the malate-proton symport. Two distinct clones affected on malate transport were obtained. Both were able to grow on a medium with glycerol or ethanol but not with DL-malic, succinic, oxoglutaric and oxaloacetic acids as the sole carbon and energy sources. However, while one of the mutants (Mal7) displayed activity levels for the enzymes malate dehydrogenase, isocitrate lyase, and phosphoenolpyruvate carboxykinase similar to those of the wild strain, in the other mutant type (Mal6) the activities for the same enzymes were significantly reduced. Plasma membranes from derepressed cells of the wild strain and of the mutants Mal6 and Mal7 were isolated and the protein analysed by SDS-PAGE. The electrophoretic patterns of these preparations differed in a polypeptide with an apparent molecular mass of about 28 kDa, which was absent only in the mutant Mal7. The results indicated that Mal7 can be affected in a gene that encodes a malate carrier in K. marxianus.