Tumor heterogeneity affects the precision of microarray analysis.

Microarray-based analysis of global gene expression patterns defines groups of genes that correlate with specific tumor types and prognosis, but the identified genes may not all be of equal clinical utility due to technical factors that affect the precision of their measurement. To analyze how technical variability in measured expression levels may impact microarray-based analysis in a clinical setting, we used Ewing sarcoma/peripheral neuroectodermal tumor (EWS/PNET) in a model system that replicates the clinical scenario in which microarray-based analysis of gene expression will likely occur, namely analysis of a fresh tumor sample by a single chip. By comparing variability of measured expression due to purely technical factors with variability due to biologic factors, we confirm that variability is dependent on the level of gene expression. We also demonstrate that the variability in expression level from either cell line or tumor samples is significantly higher than can be attributed to specific probe sets that have an intrinsically poor performance. These results have significant impact on the application of cDNA microarray chip for molecular analysis performed in a clinical setting.     

Effect of vernolide-A, a sesquiterpene lactone from Vernonia cinerea L., on cell-mediated immune response in B16F-10 metastatic melanoma-bearing mice

One of the major reasons for the rapid progression of cancers is the ability of tumor cells to escape from the immune surveillance mechanism of the body. Modulation of immune responses is highly relevant in tumor cell destruction. Effect of vernolide-A on the cell-mediated immune (CMI) response in metastatic condition was studied using C57BL/6 mice model. Administration of vernolide-A enhanced natural killer (NK) cell activity, antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent complement-mediated cytotoxicity (ACC) and the activity was observed in treated group much earlier compared with the metastatic tumor-bearing control. Administration of vernolide-A significantly enhanced the production of interleukin (IL)-2 and interferon-gamma (IFN-γ) in metastatic tumor-bearing animals. In addition, vernolide-A significantly down-regulated the serum levels of proinflammatory cytokines such as IL-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and granulocyte-macrophage colony-stimulating factor (GM-CSF) during metastasis. All these results demonstrate that vernolide-A could enhance the immune response against metastatic progression of B16F-10 melanoma cells in mice.     

Cadmium induces autophagy through ROS-dependent activation of the LKB1-AMPK signaling in skin epidermal cells

Cadmium is a toxic heavy metal which is environmentally and occupationally relevant. The mechanisms underlying cadmium-induced autophagy are not yet completely understood. The present study shows that cadmium induces autophagy, as demonstrated by the increase of LC3-II formation and the GFP-LC3 puncta cells. The induction of autophagosomes was directly visualized by electron microscopy in cadmium-exposed skin epidermal cells. Blockage of LKB1 or AMPK by siRNA transfection suppressed cadmium-induced autophagy. Cadmium-induced autophagy was inhibited in dominant-negative AMPK-transfected cells, whereas it was accelerated in cells transfected with the constitutively active form of AMPK. mTOR signaling, a negative regulator of autophagy, was downregulated in cadmium-exposed cells. In addition, cadmium generated reactive oxygen species (ROS) at relatively low levels, and caused poly(ADP-ribose) polymerase-1 (PARP) activation and ATP depletion. Inhibition of PARP by pharmacological inhibitors or its siRNA transfection suppressed ATP reduction and autophagy in cadmium-exposed cells. Furthermore, cadmium-induced autophagy signaling was attenuated by either exogenous addition of catalase and superoxide dismutase, or by overexpression of these enzymes. Consequently, these results suggest that cadmium-mediated ROS generation causes PARP activation and energy depletion, and eventually induces autophagy through the activation of LKB1-AMPK signaling and the down-regulation of mTOR in skin epidermal cells.     

Ameliorative action of <Emphasis Type="Italic">Vernonia cinerea</Emphasis> L. on cyclophosphamide-induced immunosuppression and oxidative stress in mice

Cyclophosphamide (CTX) is a widely used antineoplastic drug, which could cause toxicity to normal cells due to its toxic metabolites. The use of CTX in treating cancer patients is limited due to its severe toxicity induced mainly by oxidative stress. The present study reports the protective role of Vernonia cinerea L. against the CTX-induced toxicity in Balb/c mice. Intraperitoneal administration of the extract significantly increased the total WBC Count, bone marrow cellularity, α-esterase positive cells, and weights of lymphoid organs in CTX-treated animals, when compared with CTX control mice. Administration of V. cinerea was found to reduce the enhanced level of alkaline phosphatase, glutamate pyruvate transaminase, lipid peroxidation, and also significantly increased the reduced glutathione level in CTX-treated animals. Histopathological analysis of small intestine also suggests that extract could reduce the CTX-induced intestinal damage. The level of proinflammatory cytokine TNF-α, which was elevated during CTX administration, was significantly reduced by the V. cinerea extract administration. The lowered levels of other cytokines like IFN-γ, IL-2, GM-CSF, after CTX treatment were also found to be increased by extract administration. Administration of V. cinerea did not compromise the anti-neoplastic activity of CTX. Infact, there was a synergistic action of CTX and V. cinerea in reducing the solid tumors in mice. Methanolic extract of V. cinerea given intraperitoneally (i.p.) showed a significant chemoprotective activity without compromising the chemotherapeutic efficacy of CTX, indicating its possible use as an adjuvant during chemotherapy.     

Apigenin induces apoptosis in human leukemia cells and exhibits anti-leukemic activity in vivo

In this study, we investigated the functional role of Akt and c-jun-NH(2)-kinase (JNK) signaling cascades in apigenin-induced apoptosis in U937 human leukemia cells and anti-leukemic activity of apigenin in vivo. Apigenin induced apoptosis by inactivation of Akt with a concomitant activation of JNK, Mcl-1 and Bcl-2 downregulation, cytochrome c release from mitochondria, and activation of caspases. Constitutively active myristolated Akt prevented apigenin-induced JNK, caspase activation, and apoptosis. Conversely, LY294002 and a dominant-negative construct of Akt potentiated apigenin-induced apoptosis in leukemia cells. Interruption of the JNK pathway showed marked reduction in apigenin-induced caspase activation and apoptosis in leukemia cells. Furthermore, in vivo administration of apigenin resulted in attenuation of tumor growth in U937 xenografts accompanied by inactivation of Akt and activation of JNK. Attenuation of tumor growth in U937 xenografts by apigenin raises the possibility that apigenin may have clinical implications and can be further tested for incorporating in leukemia treatment regimens.