Studies on Herbal Compounds With Broad-Spectrum Anti-Cancer Activity through Generation of Reactive Oxygen Species

together with invasion of the surrounding tissue and the spread of malignant cells (Karin M et al., 2005) by the ability to implant into distant sites through metastasis. In a living organism, the multiplication of cells is regulated. Within a young animal, the cell multiplication actually exceeds cell death, as a result animal increases in size. Very occasionally, the complicated mechanisms that regulate cell multiplication fail and a cell begins to grow and divide although the body has no need for further cells of its type. The indefinite clonal expansion of the cell ultimately gives rise to a tumor. Tumor in medical language simply means swelling or lump, neoplastic, inflammatory or other. In common language, however, it is synonymous with 'neoplasm', either benign or malignant. The benign tumor does not spread to its surrounding tissues. On the other hand malignant tumor possesses a specific characteristic feature known as metastasis which means spread of tumor cells from their site of origin and establishment of areas of secondary growth (Fig 1). The term ‘cancer’ refers to specifically malignant forms of tumor

Leishmania donovani Infection of Human Myeloid Dendritic Cells Leads to a Th1 Response in CD4+ T Cells from Healthy Donors and Patients with Kala-Azar.

The role played by dendritic cells (DCs) in Leishmania donovani infection is poorly understood. Here, we report that L. donovani amastigotes efficiently infect human peripheral-blood monocyte–derived DCs. Opsonization with normal human serum enhanced the infectivity of amastigotes and promastigotes only marginally. Surface attachment versus internalization was distinguished by incubation of DCs with live, fluorescein isothiocyanate–labeled parasites, followed by quenching with crystal violet. Infection with amastigotes was accompanied by DC maturation, as was evident from the up-regulation of maturation-associated cell-surface markers, the nuclear translocation of RelB, and the release of cytokines. Amastigote-primed DCs produced inflammatory cytokines in response to subsequent treatment with interferon-g or anti-CD40 monoclonal antibody. When cocultured, amastigote-infected DCs induced T helper cell type 1 (Th1) responses both in naive allogeneic CD4+ T cells and in autologous CD4+ T cells from patients with kala-azar and up-regulated the expression of T-bet. Our data reveal that infection with L. donovani amastigotes induces a Th1 cytokine milieu in both DCs and T cells

N-acetyl cysteine enhances imatinib-induced apoptosis of Bcr-Abl+ cells by endothelial nitric oxide synthase-mediated production of nitric oxide

Introduction Imatinib, a small-molecule inhibitor of the Bcr-Abl kinase, is a successful drug for treating chronic myeloid leukemia (CML). Bcr-Abl kinase stimulates the production of H2O2, which in turn activates Abl kinase. We therefore evaluated whether N-acetyl cysteine (NAC), a ROS scavenger improves imatinib efficacy. Materials and methods Effects of imatinib and NAC either alone or in combination were assessed on Bcr-Abl? cells to measure apoptosis. Role of nitric oxide (NO) in NAC-induced enhanced cytotoxicity was assessed using pharmacological inhibitors and siRNAs of nitric oxide synthase isoforms. We report that imatinib-induced apoptosis of imatinib-resistant and imatinib-sensitive Bcr-Abl? CML cell lines and primary cells from CML patients significantly enhanced by co-treatment with NAC compared to imatinib treatment alone. In contrast, another ROS scavenger glutathione reversed imatinib-mediated killing. NAC-mediated enhanced killing correlated with cleavage of caspases, PARP and up-regulation and down regulation of pro- and anti-apoptotic family of proteins, respectively. Co-treatment with NAC leads to enhanced production of nitric oxide (NO) by endothelial nitric oxide synthase (eNOS). Involvement of eNOS dependent NO in NACmediated enhancement of imatinib-induced cell death was confirmed by nitric oxide synthase (NOS) specific pharmacological inhibitors and siRNAs. Indeed, NO donor sodium nitroprusside (SNP) also enhanced imatinib-mediated apoptosis of Bcr-Abl? cells. Conclusion NAC enhances imatinib-induced apoptosis of Bcr-Abl? cells by endothelial nitric oxide synthasemediated production of nitric oxide

Involvement of ROS in Chlorogenic Acid-Induced Apoptosis of Bcr-Abl+ CML Cells

Chlorogenic acid (Chl) has been reported to possess a wide range of biological and pharmacological properties including induction of apoptosis of Bcr-Abl+ chronic myeloid leukemia (CML) cell lines and clinical leukemia samples via inhibition of Bcr-Abl phosphorylation. Here we studied the mechanisms of action of Chl in greater detail. Chl treatment induced an early accumulation of intracellular reactive oxygen species (ROS) in Bcr-Abl+ cells leading to downregulation of Bcr-Abl phosphorylation and apoptosis. Chl treatment upregulated death receptor DR5 and induced loss of mitochondrial membrane potential accompanied by release of cytochrome c from the mitochondria to the cytosol. Pharmacological inhibition of caspase-8 partially inhibited apoptosis, whereas caspase-9 and pan-caspase inhibitor almost completely blocked the killing. Knocking down DR5 using siRNA completely attenuated Chlinduced caspase-8 cleavage but partially inhibited apoptosis. Antioxidant NAC attenuated Chl-induced oxidative stress-mediated inhibition of Bcr-Abl phosphorylation, DR5 upregulation, caspase activation and CML cell death. Our data suggested the involvement of parallel death pathways that converged in mitochondria. The role of ROS in Chl-induced death was confirmed with primary leukemia cells fromCML patients in vitro as well as in vivo in nude mice bearing K562 xenografts. Collectively, our results establish the role of ROS for Chl-mediated preferential killing of Bcr-Abl+ cells

Thyrostimulin Regulates Osteoblastic Bone Formation During Early Skeletal Development

The ancestral glycoprotein hormone thyrostimulin is a heterodimer of unique glycoprotein hormone subunit alpha (GPA)2 and glycoprotein hormone subunit beta (GPB)5 subunits with high affinity for the TSH receptor. Transgenic overexpression of GPB5 in mice results in cranial abnormalities, but the role of thyrostimulin in bone remains unknown. We hypothesized that thyrostimulin exerts paracrine actions in bone and determined: 1) GPA2 and GPB5 expression in osteoblasts and osteoclasts, 2) the skeletal consequences of thyrostimulin deficiency in GPB5 knockout (KO) mice, and 3) osteoblast and osteoclast responses to thyrostimulin treatment. Gpa2 and Gpb5 expression was identified in the newborn skeleton but declined rapidly thereafter. GPA2 and GPB5 mRNAs were also expressed in primary osteoblasts and osteoclasts at varying concentrations. Juvenile thyrostimulin-deficient mice had increased bone volume and mineralization as a result of increased osteoblastic bone formation. However, thyrostimulin failed to induce a canonical cAMP response or activate the noncanonical Akt, ERK, or mitogen-activated protein kinase (P38) signaling pathways in primary calvarial or bone marrow stromal cell-derived osteoblasts. Furthermore, thyrostimulin did not directly inhibit osteoblast proliferation, differentiation or mineralization in vitro. These studies identify thyrostimulin as a negative but indirect regulator of osteoblastic bone formation during skeletal developmen

Granulocyte–macrophage colony-stimulating factor drives monocytes to CD14low CD83+ DCSIGN– interleukin-10-producing myeloid cells with differential effects on T-cell subsets

Granulocyte–macrophage colony-stimulating factor (GM-CSF) has long been found to have growth-promoting effects on multipotent haematopoietic lineages, specifically granulocytes and macrophages. GM-CSF combined with interleukin-4 (IL-4) drives monocytes to become myeloid dendritic cells (mDCs) in vitro. We report that culturing human monocytes with GM-CSF alone generates myeloid cells (GM-Mono) that have lower expression of CD14 than monocytes and that fail to express DC-SIGN. GM-Monos, however, express CD83 and the transcription factor PU.1, although at a lower level than the conventional mDCs generated in the presence of GM-CSF and IL-4. On stimulation with tumour necrosis factor-α, interferon-γ and anti-CD40 monoclonal antibody, the GM-Monos predominantly produced IL-10 but were less efficient in IL-12 production. In a primary allogeneic mixed lymphocyte reaction, GM-Monos induced hyporesponsiveness and IL-10-biased cytokine production in CD4+ T cells. In fresh mixed lymphocyte reaction, GM-Monos inhibited conventional mDC-induced allogeneic CD4+ T-cell proliferation. GM-Mono-induced inhibition of allogeneic CD4+ T-cell proliferation was partially attributed to IL-10. Interestingly, GM-Monos neither induced hyporesponsiveness in allogeneic CD8+ T cells nor inhibited conventional mDC-induced allogeneic CD8+ T-cell proliferation. Taken together, we characterize monocyte-derived CD14low CD83+ cells generated by GM-CSF that can induce tolerance or stimulation of T cells depending on T-cell subsets