A novel copper complex induces ROS generation in doxorubicin resistant Ehrlich ascitis carcinoma cells and increases activity of antioxidant enzymes in vital organs in vivo.

BACKGROUND: In search of a suitable GSH-depleting agent, a novel copper complex viz., copper N-(2-hydroxyacetophenone) glycinate (CuNG) has been synthesized, which was initially found to be a potential resistance modifying agent and later found to be an immunomodulator in mice model in different doses. The objective of the present work was to decipher the effect of CuNG on reactive oxygen species (ROS) generation and antioxidant enzymes in normal and doxorubicin-resistant Ehrlich ascites carcinoma (EAC/Dox)-bearing Swiss albino mice. METHODS: The effect of CuNG has been studied on ROS generation, multidrug resistance-associated protein1 (MRP1) expression and on activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). RESULTS: CuNG increased ROS generation and reduced MRP1 expression in EAC/Dox cells while only temporarily depleted glutathione (GSH) within 2 h in heart, kidney, liver and lung of EAC/Dox bearing mice, which were restored within 24 h. The level of liver Cu was observed to be inversely proportional to the level of GSH. Moreover, CuNG modulated SOD, CAT and GPx in different organs and thereby reduced oxidative stress. Thus nontoxic dose of CuNG may be utilized to reduce MRP1 expression and thus sensitize EAC/Dox cells to standard chemotherapy. Moreover, CuNG modulated SOD, CAT and and GPx activities to reduce oxidative stress in some vital organs of EAC/Dox bearing mice. CuNG treatment also helped to recover liver and renal function in EAC/Dox bearing mice. CONCLUSION: Based on our studies, we conclude that CuNG may be a promising candidate to sensitize drug resistant cancers in the clinic.

Overcoming drug-resistant cancer by a newly developed copper chelate through host-protective cytokine-mediated apoptosis.

PURPOSE: Previously, we have synthesized and characterized a novel Cu(II) complex, copper N-(2-hydroxy acetophenone) glycinate (CuNG). Herein, we have determined the efficacy of CuNG in overcoming multidrug-resistant cancer using drug-resistant murine and human cancer cell lines. EXPERIMENTAL DESIGN: Action of CuNG following single i.m. administration (5 mg/kg body weight) was tested in vivo on doxorubicin-resistant Ehrlich ascites carcinoma (EAC/Dox)-bearing mice and doxorubicin-resistant sarcoma 180-bearing mice. Tumor size, ascitic load, and survival rates were monitored at regular intervals. Apoptosis of cancer cells was determined by cell cycle analysis, confocal microscopy, Annexin V binding, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay ex vivo. IFN-gamma and tumor necrosis factor-alpha were assayed in the culture supernatants of in vivo and in vitro CuNG-treated splenic mononuclear cells from EAC/Dox-bearing mice and their apoptogenic effect was determined. Source of IFN-gamma and changes in number of T regulatory marker-bearing cells in the tumor site following CuNG treatment were investigated by flow cytometry. Supernatants of in vitro CuNG-treated cultures of peripheral blood mononuclear cells from different drug-insensitive cancer patients were tested for presence of the apoptogenic cytokine IFN-gamma and its involvement in induction of apoptosis of doxorubicin-resistant CEM/ADR5000 cells. RESULTS: CuNG treatment could resolve drug-resistant cancers through induction of apoptogenic cytokines, such as IFN-gamma and/or tumor necrosis factor-alpha, from splenic mononuclear cells or patient peripheral blood mononuclear cells and reduce the number of T regulatory marker-bearing cells while increase infiltration of IFN-gamma-producing T cells in the ascetic tumor site. CONCLUSION: Our results show the potential usefulness of CuNG in immunotherapy of drug-resistant cancers irrespective of multidrug resistance phenotype.

Modulation of doxorubicin sensitivity by a novel organic compound, oxalyl bis (N-phenyl) hydroxamic acid on acetyl aminofluorene-induced preneoplastic hepatocytes.

Development of biochemical modulators and application of the same with anticancer drugs is a current approach of modern cancer chemotherapy. We report the effect of two novel hydroxamic acid derivatives, viz. oxaly bis (N-phenyl) hydroxamic acid (OBPHA) and succinyl bis (N-phenyl) hydroxamic acid (SBPHA) on doxorubicin sensitivity and on P-glycoprotein (P-gp) in acetyl amino fluorene (AAF) induced preneoplastic hepatocytes in vitro. OBPHA increases doxorubicin sensitivity in AAF induced preneoplastic hepatocytes compared to normal hepatocytes. SBPHA, with an additional -CH(2)-CH(2)- group than OBPHA does not modulate the sensitivity of doxorubicin. The mechanism of action of OBPHA and SBPHA and their in vivo toxicity on male Swiss mice has been studied. OBPHA in combination with doxorubicin (i.e. OBPHA+doxorubicin) has higher antitumour activity compared to doxorubicin alone group; in consequence, OBPHA may decrease the dose related side effect of doxorubicin.

Synthesis, characterization and biological properties of a novel copper complex.

The study of copper complex in relation to cancer is important in many ways. A novel copper complex has been synthesized with non toxic ligand, viz. potassium salt of N-(2-hydroxy acetophenone) glycinate (NHAG). The structure of the complex has been determined by spectroscopic means. Toxicity and antitumor property of the complex has been studied in vivo. Though the complex is toxic at higher doses, lower non toxic doses of the complex deplete glutathione (GSH). GSH depleting property of the complex may be utilized to sensitize drug resistant cells where resistance is due to elevated level of GSH.