14 research outputs found
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