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.

A novel copper chelate modulates tumor associated macrophages to promote anti-tumor response of T cells.

BACKGROUND: At the early stages of carcinogenesis, the induction of tumor specific T cell mediated immunity seems to block the tumor growth and give protective anti-tumor immune response. However, tumor associated macrophages (TAMs) might play an immunosuppressive role and subvert this anti tumor immunity leading to tumor progression and metastasis. METHODOLOGY/PRINCIPAL FINDINGS: The Cu (II) complex, (chelate), copper N-(2-hydroxy acetophenone) glycinate (CuNG), synthesized by us, has previously been shown to have a potential usefulness in immunotherapy of multiple drug resistant cancers. The current study demonstrates that CuNG treatment of TAMs modulates their status from immunosuppressive to proimmunogenic nature. Interestingly, these activated TAMs produced high levels of IL-12 along with low levels of IL-10 that not only allowed strong Th1 response marked by generation of high levels of IFN-gamma but also reduced activation induced T cell death. Similarly, CuNG treatment of peripheral blood monocytes from chemotherapy and/or radiotherapy refractory cancer patients also modulated their cytokine status. Most intriguingly, CuNG treated TAMs could influence reprogramming of TGF-beta producing CD4(+)CD25(+) T cells toward IFN-gamma producing T cells. CONCLUSION/SIGNIFICANCE: Our results show the potential usefulness of CuNG in immunotherapy of drug-resistant cancers through reprogramming of TAMs that in turn reprogram the T cells and reeducate the T helper function to elicit proper anti-tumorogenic Th1 response leading to effective reduction in tumor growth.

Kinetoplastid membrane protein-11 DNA vaccination induces complete protection against both pentavalent antimonial-sensitive and -resistant strains of Leishmania donovani that correlates with inducible nitric oxide synthase activity and IL-4 generation: evidence for mixed Th1- and Th2-like responses in visceral leishmaniasis.

The emergence of an increasing number of Leishmania donovani strains resistant to pentavalent antimonials (SbV), the first line of treatment for visceral leishmaniasis worldwide, accounts for decreasing efficacy of chemotherapeutic interventions. A kinetoplastid membrane protein-11 (KMP-11)-encoding construct protected extremely susceptible golden hamsters from both pentavalent antimony responsive (AG83) and antimony resistant (GE1F8R) virulent L. donovani challenge. All the KMP-11 DNA vaccinated hamsters continued to survive beyond 8 mo postinfection, with the majority showing sterile protection. Vaccinated hamsters showed reversal of T cell anergy with functional IL-2 generation along with vigorous specific anti-KMP-11 CTL-like response. Cytokines known to influence Th1- and Th2-like immune responses hinted toward a complex immune modulation in the presence of a mixed Th1/Th2 response in conferring protection against visceral leishmaniasis. KMP-11 DNA vaccinated hamsters were protected by a surge in IFN-gamma, TNF-alpha, and IL-12 levels along with extreme down-regulation of IL-10. Surprisingly the prototype candidature of IL-4, known as a disease exacerbating cytokine, was found to have a positive correlation to protection. Contrary to some previous reports, inducible NO synthase was actively synthesized by macrophages of the protected hamsters with concomitant high levels of NO production. This is the first report of a vaccine conferring protection to both antimony responsive and resistant Leishmania strains reflecting several aspects of clinical visceral leishmaniasis.