AKT-driven epithelial-mesenchymal transition is affected by copper bioavailability in HER2 negative breast cancer cells via a LOXL2-independent mechanism.

BACKGROUND: The main mechanism underlying cancer dissemination is the epithelial to mesenchymal transition (EMT). This process is orchestrated by cytokines like TGFß, involving "non-canonical" AKT- or STAT3-driven pathways. Recently, the alteration of copper homeostasis seems involved in the onset and progression of cancer. METHODS: We expose different breast cancer cell lines, including two triple negative (TNBC) ones, an HER2 enriched and one cell line representative of the Luminal A molecular subtype, to short- or long-term copper-chelation by triethylenetetramine (TRIEN). We analyse changes in the expression of EMT markers (E-cadherin, fibronectin, vimentin and αSMA), in the levels and activity of extracellular matrix components (LOXL2, fibronectin and MMP2/9) and of copper homeostasis markers by Western blot analyses, immunofluorescence, enzyme activity assays and RT-qPCR. Boyden Chamber and wound healing assays revealed the impact of copper chelation on cell migration. Additionally, we explored whether perturbation of copper homeostasis affects EMT prompted by TGFß. Metabolomic and lipidomic analyses were applied to search the effects of copper chelation on the metabolism of breast cancer cells. Finally, bioinformatics analysis of data on breast cancer patients obtained from different databases was employed to correlate changes in kinases and copper markers with patients' survival. RESULTS: Remarkably, only HER2 negative breast cancer cells differently responded to short- or long-term exposure to TRIEN, initially becoming more aggressive but, upon prolonged exposure, retrieving epithelial features, reducing their invasiveness. This phenomenon may be related to the different impact of the short and prolonged activation of the AKT kinase and to the repression of STAT3 signalling. Bioinformatics analyses confirmed the positive correlation of breast cancer patients' survival with AKT activation and up-regulation of CCS. Eventually, metabolomics studies demonstrate a prevalence of glycolysis over mitochondrial energetic metabolism and of lipidome changes in TNBC cells upon TRIEN treatment. CONCLUSIONS: We provide evidence of a pivotal role of copper in AKT-driven EMT activation, acting independently of HER2 in TNBC cells and via a profound change in their metabolism. Our results support the use of copper-chelators as an adjuvant therapeutic strategy for TNBC.

Cytotoxic activity of l-lysine alpha-oxidase against leukemia cells.

Cancer cells exhibit higher proliferation rates than normal cells, and as a consequence, a higher nutritional demand for metabolites such as amino acids. Such cells demonstrate high expression of amino acid transporters and are significantly dependent on the external uptake of amino acids. Moreover, some types of cancer cells exhibit oncogenic mutations that render them auxotrophic to certain amino acids. This metabolic difference between tumor and normal cells has been explored for developing anticancer drugs. Enzymes capable of depleting certain amino acids in the bloodstream can be employed to inhibit the proliferation of cancer cells and promote cell death. Certain microbial enzymes, such as l-asparaginase and l-amino acid oxidases, have been studied for this purpose. In this paper, we discuss the role of l-asparaginase, the only enzyme currently used as a chemotherapeutic agent. We also review the studies on a new potential antineoplastic agent, l-lysine α-oxidase, an enzyme of l-amino acid oxidase family.

Secreted LOXL2 is a novel therapeutic target that promotes gastric cancer metastasis via the Src/FAK pathway.

The purpose of this study was to investigate invasion- and metastasis-related genes in gastric cancer. To this end, we used the transwell system to select a highly invasive subcell line from minimally invasive parent cells and compared gene expression in paired cell lines with high- and low-invasive potentials. Lysyl oxidase-like 2 (LOXL2) was overexpressed in the highly invasive subcell line. Immunohistochemical analysis revealed that LOXL2 expression was markedly increased in carcinoma relative to normal epithelia, and this overexpression in primary tumor was significantly associated with depth of tumor invasion, lymph node metastasis and poorer overall survival. Moreover, LOXL2 expression was further increased in lymph node metastases compared with primary cancer tissues. RNA interference-mediated knockdown and ectopic expression of LOXL2 showed that LOXL2 promoted tumor cell invasion in vitro and increased gastric carcinoma metastasis in vivo. Subsequent mechanistic studies showed that LOXL2 could activate both the Snail/E-cadherin and Src kinase/Focal adhesion kinase (Src/FAK) pathways. However, secreted LOXL2 induced gastric tumor cell invasion and metastasis exclusively via the Src/FAK pathway. Expression correlation analysis in gastric carcinoma tissues also revealed that LOXL2 promoted invasion via the Src/FAK pathway but not the Snail/E-cadherin pathway. We then evaluated secreted LOXL2 as a target for gastric carcinoma treatment and found that an antibody against LOXL2 significantly inhibited tumor growth and metastasis. Overall, our data revealed that LOXL2 overexpression, a frequent event in gastric carcinoma progression, contributes to tumor cell invasion and metastasis, and LOXL2 may be a therapeutic target for preventing and treating metastases.

[Molecular and biochemical principles of neoplasm enzyme therapy].

Bacterial enzymes are antineoplastic perspective agents in oncology. Current strategy of tumor enzyme therapy is primarily based on the strictly defined differences of biochemical properties between normal and tumor cells and more precisely on their different sensitivity to deficit of essential growth factors, including amino acids. The growth inhibitory effects of three bacterial enzymes: glutamine (asparagin)ase, methionine gamma-lyase and lysine alpha-oxidase were demonstrated in in vitro and in vivo using several tumor lines. These results suggest that commercial production of certified standard enzyme preparations and their knowledge-based rational application will provide a new potent anti-tumor preparations employed in oncology.

[Effect of L-lysine-alpha-oxidase on skin carcinoma induced by methylcholanthrene in mice]. / Vozdeisvie L-lizin-al'fa-oksidazy na kartsinomu kozhi myshei, indutsirovannuiu metilkholantrenom.

Effect of enzyme L-lisyne-a-oxidase in complex with gel (Sakap) on carcinoma of the skin of mice induced by methylcholantrene was studied. Gel application once daily during 3 weeks decreased carcinoma dimensions on 40 per cent.

Induction of cytotoxic oxidative stress by D-alanine in brain tumor cells expressing Rhodotorula gracilis D-amino acid oxidase: a cancer gene therapy strategy.

Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) generated in the stereoselective deamination of D-amino acids catalyzed by D-amino acid oxidase (DAAO). H2O2 readily crosses cellular membranes and damages DNA, proteins, and lipids. The scarcity of DAAO substrates in mammalian organisms and its co-localization with catalase in the peroxisomal matrix suggested that the cytotoxicity of ROS could be harnessed by administration of D-amino acids to tumor cells ectopically expressing DAAO in the cytoplasm. To evaluate this hypothesis, the cDNA encoding the highly active DAAO from the red yeast Rhodotorula gracilis was mutated to remove the carboxy-terminal peroxisomal targeting sequence. A clonal line of 9L glioma cells stably transfected with this construct (9Ldaao17) was found to synthesize active R. gracilis DAAO. Exposure of 9Ldaao17 cells to D-alanine resulted in cytotoxicity at concentrations that were nontoxic to parental 9L cells. Depletion of cellular glutathione further sensitized 9Ldaao17 cells to D-alanine (D-Ala). This result, combined with stimulation of pentose phosphate pathway activity and the production of extracellular H2O2 by 9Ldaao17 cells incubated with D-alanine implicates oxidative stress as the mediator of cytotoxicity. These results demonstrate that expression of R. gracilis DAAO in tumor cells confers chemosensitivity to D-alanine that could be exploited as a novel cancer gene therapy paradigm.

Use of nitric oxide synthase inhibitors as a novel treatment for septic shock.

OBJECTIVE: To review the current literature regarding the role of nitric oxide (NO) in the pathogenesis of septic shock and to describe the potential role of NO synthase (NOS) inhibitors in the treatment of septic shock. DATA SOURCES: A MEDLINE, Cancerlit, Biosis, Scisearch, CBAC, bibliography, and current journal search of applicable articles on the involvement of NO in mediating septic shock and the use of NOS inhibitors in septic shock was conducted. Articles that were searched included animal and human studies from January 1990 to August 1994. STUDY SELECTION: Because of the preliminary nature of the research involving NOS inhibitors in septic shock, all available studies were evaluated. DATA SYNTHESIS: NO appears to have a role in the mediation of the hemodynamic instability associated with septic shock. Cytokines and endotoxin stimulate synthesis of the inducible NOS, which produces large amounts of NO over an extended period of time. NO may be the key mediator in the pathogenesis of septic shock. Derivatives of the precursor to NO, L-arginine, have been used to investigate the role of NO in septic shock and as possible therapeutic agents. Comparison of study results among animal studies shows much variability. This variability may be attributable to differences in dosing regimens and models of septic shock. Data obtained from human studies are more consistent, but are limited to a few case series. Results indicate that NOS inhibitors increase blood pressure and systemic vascular resistance and decrease cardiac output. The effects of NOS inhibitors on morbidity and mortality have not been assessed because of the lack of an appropriate sample size. CONCLUSIONS: NO appears to play a role in septic shock; however, the use of NOS inhibitors to treat septic shock requires further studies to determine an appropriate dosing regimen and to determine the effects of these agents on morbidity and mortality.

The effect of L-amino acid oxidase on activity of melphalan against an intracranial xenograft.

We have previously shown that diet restriction-induced depletion of large neutral amino acids (LNAAs) in murine plasma to 46% of control significantly enhances intracranial delivery of melphalan without enhancing delivery to other organs. Studies have now been conducted to determine whether more substantial LNAA depletion could further enhance intracranial delivery of melphalan. Treatment with L-amino acid oxidase (LOX) significantly depleted murine plasma LNAAs: phenylalanine, leucine, and tyrosine (> 95%); methionine (83%); isoleucine (70%); and valine (46%). Experiments evaluating the intracellular uptake of melphalan and high-pressure liquid chromatography quantitation of melphalan metabolites revealed, however, that melphalan is rapidly degraded in the presence of LOX, and that the timing of the administration of melphalan following the use of LOX to deplete LNAAs is crucial. Conditions were found under which LOX-mediated degradation of melphalan was minimized and LNAA depletion was maximized, resulting in a potentiation of the antitumor effect of melphalan on human glioma xenografts in nude mice. Such potentiation could not be obtained using diet restriction alone.

The effects of nitric oxide inhibition on regional hemodynamics during hyperdynamic endotoxemia.

OBJECTIVE: To determine the effect of the inhibition of nitric oxide (NO) on selective organ blood flow in endotoxin-induced sepsis. DESIGN: Nonrandomized, controlled experiment. SETTING: Animal research facility in Brooklyn, NY. PARTICIPANTS: Eleven mongrel dogs. INTERVENTION: Eleven dogs were divided into one of two groups: a control group (n = 5) and an endotoxin-treated group (n = 6). The animals were anesthetized, and electromagnetic and ultrasonic flow probes were placed on the distal aorta, right internal carotid artery, superior mesenteric artery, and left renal artery. Sepsis was induced with a 60-mg/kg intravenous injection of Escherichia coli endotoxin. When the arterial blood pressure decreased to less than 60 mm Hg despite adequate fluid resuscitation, NO synthesis was inhibited with a 25-mg/kg intravenous administration of NG-monomethyl-L-arginine. After 15 minutes of inhibition, a 400-mg/kg intravenous administration of L-arginine, the substrate of NO synthase enzyme, was given. Physiologic measurements were continued for 15 minutes thereafter. MAIN OUTCOME MEASURES: Heart rate, blood pressure, central venous pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, cardiac output, hematocrit, arterial and venous blood gas values, and blood flow measurements of right internal carotid artery, superior mesenteric artery, left renal artery, and distal aorta. RESULTS: Control animals did not demonstrate a significant (P > .05) decrease in blood flow in the internal carotid artery, superior mesenteric artery, and distal aorta after the administration of NG-monomethyl-L-arginine. The endotoxin-treated group showed a significant (P < .05) decrease in organ perfusion when treated with the NO synthase inhibitor, NG-monomethyl-L-arginine. CONCLUSIONS: Inhibition of NO production in the treatment of sepsis caused a significant decrease in blood flow to all vascular beds in vivo. The role, if any, of the inhibition of NO in the treatment of sepsis is questioned.

[Anti-invasive and anti-metastatic effect of lysine oxidase from Trichoderma sp. in vitro and in vivo]. / Issledovanie antiinvazivnogo i antimetastaticheskogo deistviia lizinoksiday iz Trichoderma sp. in vitro i in vivo.

A new fungal strain, Trichoderma sp., discovered in Moscow, produces the antitumor enzyme, lysine-oxidase, which demonstrates an anti-invasive effect in vitro and anti-metastatic activity in vivo. Maximal inhibition of the in vitro invasion of MM1 clone cells was obtained when the tumor cells were pretreated with 2.5 mU/ml of lysine-oxidase; the pretreatment caused a 1.9-times reduction in cell growth and a 1.6-times reduction in the invasive capacity. We studied its anti-metastatic effect on the spreading Lewis lung carcinoma (3LL) in mice from which the primary tumor had been removed. The administration of the enzyme (50 U/kg, i.v.) significantly decreased not only the extent but the number of lung metastases, as compared with the untreated mice. In addition to that, the lysine-oxidase treatment considerably increases the life-span of mice from which the primary tumor had been removed (200 days after 3LL implantation, lysine-oxidase treatment caused surviving of 50% mice in experimental group).

[Antimetastatic effect of L-lysine-alpha oxidase]. / Antimetastaticheskii éffekt L-lizin-alfa-oksidazy.

The influence of a new antitumor enzyme L-lysine alpha-oxidase on Lewis lung carcinoma spreading was studied in mice in which primary tumor had been removed. The enzyme was found to significantly decrease the extent and number of lung metastases as compared to mice which hadn't received L-lysine alpha-oxidase. This was matched by recovery of alveolar macrophages functional activity, as assessed by adenosine deaminase and 5' nucleotidase levels in these cells. Moreover, antimetastatic and cytostatic effect was confirmed by the measuring of polyamine concentration in mice erythrocytes.

[Evaluation of antileukemic activity of L-lysine-alpha oxidase from Trichoderma sp. in chemotherapeutic experiments]. / Otsenka protivoleikoznoi aktivnosti L-lizin-alfa-oksidaza iz Trichoderma sp. v khimioterapevticheskikh opytakh.

Evidences on the antileukemic effect of L-lysine alpha-oxidase from Trichoderma sp. are presented. It is inferred that enzyme needs detail studying as a potential chemotherapeutic drug both in experimental and clinical research.