OBJECTIVETumor necrosis factor-related apoptosis-inducing ligand (TRAIL) resistance greatly limits the clinical therapeutic efficacy of TRAIL. Elucidating the molecular mechanism underlying TRAIL resistance will be fundamental to resolving this problem.

METHODSNuclear and cytoplasmic protein extraction and immuno？uorescence (IF) assay were used to detect changes in heterogeneous nuclear ribonucleoprotein K (hnRNPK) localization in H1299 cells. The evaluation of cell apoptosis in cells transfected with GFP-hnRNPK, GFP-hnRNPK S284/353A, or GFP-hnRNPK S284/353D mutant was performed using cleaved caspase-3 antibody. The gene expression of XIAP was tested by quantitative RT-PCR.

RESULTSPreviously, we reported that hnRNPK antagonized TRAIL-induced apoptosis through inhibition of PKC-mediated GSK3β phosphorylation. In this study, we further demonstrate that TRAIL treatment induces cytoplasmic accumulation of hnRNPK in H1299 cells. The hnRNPK localized in the cytoplasm has a higher capacity to antagonize TRAIL-induced apoptosis. Both ERK1/2 signaling inhibitor U0126 and ERK-phosphoacceptor-site mutant (GFP-hnRNPK S284/353A) diminish cytoplasmic accumulation of hnRNPK induced by TRAIL. Moreover, we show that XIAP is involved in hnRNPK-mediated TRAIL resistance in H1299 cells.

CONCLUSIONTaken together, these results give new insights into the understanding of the molecular mechanism associated with TRAIL resistance in lung adenocarcinoma.

Apoptosis ; physiology ; Cell Line, Tumor ; Gene Expression Regulation ; physiology ; Heterogeneous-Nuclear Ribonucleoprotein K ; genetics ; metabolism ; Humans ; Mitogen-Activated Protein Kinase 1 ; genetics ; metabolism ; Mitogen-Activated Protein Kinase 3 ; genetics ; metabolism ; TNF-Related Apoptosis-Inducing Ligand ; genetics ; metabolism ; Up-Regulation ; physiology ; X-Linked Inhibitor of Apoptosis Protein ; genetics ; metabolism

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF super family found in recent years, which widely exists in the body tissues and participates in the immune regulation, immune stability, and immune surveillance of the human body. The TRAIL receptor is expressed in the surface of a variety of cells. Recent studies show that TRAIL induces the apoptosis of tumor cells and has no significant toxic effect on normal cells. Its anti-tumor activity and safety have been widely recognized. The development of prostate cancer is regulated by the mechanisms of cell apoptosis. TRAIL can induce the apoptosis of prostate cancer cells, and therefore has a great application value in the treatment of prostate cancer.
Antineoplastic Agents ; therapeutic use ; Apoptosis ; Apoptosis Regulatory Proteins ; Humans ; Male ; Membrane Glycoproteins ; Prostatic Neoplasms ; drug therapy ; pathology ; Receptors, TNF-Related Apoptosis-Inducing Ligand ; physiology ; therapeutic use ; TNF-Related Apoptosis-Inducing Ligand ; Tumor Necrosis Factor-alpha

OBJECTIVETo explore the molecular mechanism via which the chemotherapeutic drug hydroxyurea (HU) enhances K562 cell apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

METHODSChronic myelogenous leukemia-derived K562 and SVT-35 cells were treated with recombinant soluble TRAIL (rsTRAIL) alone or combined with HU for a time course, and the cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-4-sulfophenyl-2H-tetrazolium-phenazine methosulphate assay. Western blot was performed to analyze the activation of apoptosis-related protein kinases and the expression of apoptosis inhibitor molecules.

RESULTSThe survival rates of SVT-35 and K562 cells treated with 1 μg/ml rsTRAIL for 24 hours were 32% and 93%, respectively. HU significantly increased the sensitivity of K562 cells to rsTRAIL cytotoxicity. Combination of rsTRAIL and HU resulted in the phosphorylation of rat sarcoma (RAS), mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase and in the significant reduction of apoptosis-inhibited molecule Fas associated death domain protein-like interleukin-1 beta-convening enzyme inhibitory protein and cellular inhibitor of apoptosis protein-1 in K562 cells.

CONCLUSIONSHU enhanced K562 cell sensitivity to rsTRAIL is mediated by Ras-MEK-ERK signaling pathway. Expression of antiapoptotic proteins cellular Fas associated death domain protein-like interleukin-1 beta-convening enzyme inhibitory protein and cellular inhibitor of apoptosis protein-1 is also down-regulated during this process. These results may through light on the therapeutic study of human chronic myelogenous leukemia.

Apoptosis ; drug effects ; physiology ; CASP8 and FADD-Like Apoptosis Regulating Protein ; metabolism ; Humans ; Hydroxyurea ; pharmacology ; Inhibitor of Apoptosis Proteins ; metabolism ; K562 Cells ; MAP Kinase Signaling System ; TNF-Related Apoptosis-Inducing Ligand ; pharmacology

This study was designed to investigate the effects of the prenylated flavonoid kurarinone on TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis and its underlying mechanism. A low dose of kurarinone had no significant effect on apoptosis, but this compound markedly promoted tumor cell death through elevation of Bid cleavage, cytochrome c release and caspase activation in HeLa cells treated with TRAIL. Caspase inhibitors inhibited kurarinone-mediated cell death, which indicates that the cytotoxic effect of this compound is mediated by caspase-dependent apoptosis. The cytotoxic effect of kurarinone was not associated with expression levels of Bcl-2 and IAP family proteins, such as Bcl-2, Bcl-xL, Bid, Bad, Bax, XIAP, cIAP-1 and cIAP-2. In addition, this compound did not regulate the death-inducing receptors DR4 and DR5. On the other hand, kurarinone significantly inhibited TRAIL-induced IKK activation, IkappaB degradation and nuclear translocation of NF-kappaB, as well as effectively suppressed cellular FLICE-inhibitory protein long form (cFLIPL) expression. The synergistic effects of kurarinone on TRAIL-induced apoptosis were mimicked when kurarinone was replaced by the NF-kappaB inhibitor withaferin A or following siRNA-mediated knockdown of cFLIPL. Moreover, cFLIP overexpression effectively antagonized kurarinone-mediated TRAIL sensitization. These data suggest that kurarinone sensitizes TRAIL-induced tumor cell apoptosis via suppression of NF-kappaB-dependent cFLIP expression, indicating that this compound can be used as an anti-tumor agent in combination with TRAIL.
Antineoplastic Agents/*pharmacology ; Apoptosis/*drug effects ; CASP8 and FADD-Like Apoptosis Regulating Protein/*genetics/metabolism ; Caspase 3/metabolism ; Caspase 8/metabolism ; Drug Synergism ; Enzyme Activation/drug effects ; Flavonoids/*pharmacology ; Gene Expression/drug effects ; Gene Knockdown Techniques ; HeLa Cells ; Humans ; NF-kappa B/antagonists & inhibitors/*metabolism ; Protein Transport/drug effects ; RNA, Small Interfering/genetics ; Signal Transduction ; TNF-Related Apoptosis-Inducing Ligand/*physiology ; Up-Regulation/drug effects

Microglia are the principal immune effectors in brain and participate in a series ofneurodegenerative diseases. The microglial shapes are highly plastic. The morphology is closely related with their activation status and biological functions. Cerebral ischemia could induce microglial activation, and microglial activation is subjected to precise regulation. Microglia could play either protective or neurotoxic roles in cerebral ischemia. Therefore, regulating the expression of receptors or protein molecules on microglia, inhibiting the excessive activation of microglia and production of pro-inflammatory factors, promoting the release of neuroprotective substances might be beneficial to the treatment of cerebral ischemia. The study about relationship between microglia and cerebral ischemia will shed a light on the treatment of cerebral ischemia. This paper is a review of microglial activation and regulation during cerebral ischemia as well as related therapeutic methods.
Animals ; Brain Ischemia ; metabolism ; pathology ; Class Ib Phosphatidylinositol 3-Kinase ; metabolism ; Humans ; Inflammation ; metabolism ; Microglia ; cytology ; drug effects ; metabolism ; physiology ; Neuroprotective Agents ; pharmacology ; Nitric Oxide Synthase ; metabolism ; Receptors, Purinergic P2X7 ; metabolism ; Regeneration ; TNF-Related Apoptosis-Inducing Ligand ; metabolism ; Toll-Like Receptors ; metabolism

Apoptosis induced by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) can be regulated by the epidermal growth factor (EGF) signaling pathway. In this study, recombinant adenoviral vectors that encode TRAIL gene from the hTERT/RGD promoter (AdTRAIL) was combined with drugs including gefitinib, elotinib, and cetuximab that inhibit EGFR and the EGF signaling pathway in non-small cell lung cancer (NSCLC) cell lines to investigate their antitumor activity. In vitro, compared to single reagent, AdTRAIL combined with EGFR inhibitors reduced proliferation and enhanced apoptosis in H460, A549, and SW1573 cell lines. Western blot results suggested that these effects were relative to up-regulation of pro-apoptosis protein BAX and down-regulation of p-AKT. In vivo, AdTRAIL combined with cetuximab resulted in a significant growth reduction in H460 xenografts without damage to the main organs of nude mice. Histological examination and TUNEL analyses of xenografts showed that cetuximab enhanced cell apoptosis induced by AdTRAIL. These results indicate that EGFR inhibitors enhanced AdTRAIL anti-tumor activity in NSCLC cell lines and that inhibiting the AKT pathway played an important role in this enhancement.
Adenoviridae ; genetics ; Animals ; Antibodies, Monoclonal ; pharmacology ; Antibodies, Monoclonal, Humanized ; Antineoplastic Agents ; pharmacology ; Apoptosis ; Carcinoma, Non-Small-Cell Lung ; metabolism ; pathology ; Cell Line, Tumor ; Cell Proliferation ; Cetuximab ; Drug Synergism ; Erlotinib Hydrochloride ; Female ; Genetic Therapy ; Genetic Vectors ; Humans ; Lung Neoplasms ; metabolism ; pathology ; Mice ; Mice, Nude ; Protein Kinase Inhibitors ; pharmacology ; Proto-Oncogene Proteins c-akt ; metabolism ; Quinazolines ; pharmacology ; Receptor, Epidermal Growth Factor ; antagonists & inhibitors ; Recombinant Proteins ; genetics ; metabolism ; Signal Transduction ; TNF-Related Apoptosis-Inducing Ligand ; genetics ; metabolism ; physiology ; Transfection ; Tumor Burden ; Xenograft Model Antitumor Assays ; bcl-2-Associated X Protein ; metabolism

OBJECTIVEThe aim of this study was to investigate whether the induction of caspase-8 by γ-interferon (IFNγ) renders neuroblastoma (NB) cells sensitive to tumor necrosis factor related apoptosis inducing ligand(TRAIL).

METHODSCaspase-8 mRNA expression was determined by RT-PCR. The effects of IFNγ, TRAIL, IFNγ +TRAIL and caspase-8 inhibitor+ TRAIL on the growth and apoptosis of NB cells were detected with the methods of reduction rate of Alamar Blue assay and flow cytometry. The relative caspase-8 activity was measured with colorimetric assay.

RESULTSCaspase-8 expression was detectable in CHP212 cells which were sensitive to TRAIL, with an increased expression after treatment with IFNγ. Caspase-8 was undetectable in SH-SY5Y(SY5Y) cells which were resistant to TRAIL, but an increased expression of caspase-8 mRNA was found after treatment with IFNγ. Moreover, TRAIL combined with IFNγ induced apoptosis in SY5Y cells. The relative caspase-8 activity of CHP212 cells increased with the prolonged TRAIL action time. The relative caspase-8 activity of SY5Y cells in the IFNγ+TRAIL group was significantly higher than those of the control, IFNγ, TRAIL and inhibitor groups.

CONCLUSIONSNB cells expressing caspase-8 are sensitive to TRAIL. TRAIL induces apoptosis in NB cells with an increase of relative caspase-8 activity.

Apoptosis ; drug effects ; Caspase 8 ; physiology ; Cell Line, Tumor ; Flow Cytometry ; Humans ; Interferon-gamma ; pharmacology ; Neuroblastoma ; drug therapy ; pathology ; Reverse Transcriptase Polymerase Chain Reaction ; TNF-Related Apoptosis-Inducing Ligand ; pharmacology

TNF-related apoptosis inducing ligand (TRAIL) expressions were studied in primary human brain astrocytes in response to pro-inflammatory cytokines. When astrocytes were treated with IL-1beta TNF-alphaor IFN-gamma TRAIL was induced in cultured fetal astrocytes. In particular, IFN-gammainduced the highest levels of TRAIL in cultured astrocytes. When astrocytes were pre-reated with IFN-gamma they induced apoptosis in TRAIL-sensitive Peer cells. Our results suggest that IFN-gamma modulates the expression of TRAIL in astrocytes, which may enhance cytotoxic sensitivity of infiltrating immune cells or brain cells other than astrocytes during inflammation of brain.
Tumor Necrosis Factor-alpha/genetics/*metabolism ; TNF-Related Apoptosis-Inducing Ligand ; Membrane Glycoproteins/genetics/*metabolism ; Interferon Type II/*pharmacology ; Humans ; Cells, Cultured ; Astrocytes/*cytology/drug effects/metabolism ; Apoptosis Regulatory Proteins/genetics/*metabolism ; Apoptosis/*drug effects/physiology ; Antineoplastic Agents/*pharmacology

TNF-related apoptosis inducing ligand (TRAIL) expressions were studied in primary human brain astrocytes in response to pro-inflammatory cytokines. When astrocytes were treated with IL-1beta TNF-alphaor IFN-gamma TRAIL was induced in cultured fetal astrocytes. In particular, IFN-gammainduced the highest levels of TRAIL in cultured astrocytes. When astrocytes were pre-reated with IFN-gamma they induced apoptosis in TRAIL-sensitive Peer cells. Our results suggest that IFN-gamma modulates the expression of TRAIL in astrocytes, which may enhance cytotoxic sensitivity of infiltrating immune cells or brain cells other than astrocytes during inflammation of brain.
Tumor Necrosis Factor-alpha/genetics/*metabolism ; TNF-Related Apoptosis-Inducing Ligand ; Membrane Glycoproteins/genetics/*metabolism ; Interferon Type II/*pharmacology ; Humans ; Cells, Cultured ; Astrocytes/*cytology/drug effects/metabolism ; Apoptosis Regulatory Proteins/genetics/*metabolism ; Apoptosis/*drug effects/physiology ; Antineoplastic Agents/*pharmacology

OBJECTIVETo evaluate the expression and activity of TNF-related apoptosis-inducing ligand (TRAIL) gene expressed from the hTERT promoter on colon cancer cell line HT-29.

METHODSGFP/TRAIL gene expressed from the hTERT promoter was transfected into HT-29 with adenoviral vectors system, expression and apoptosis inducing ability of GFP/TRAIL protein were determined with fluorescence-activated cell sorting (FACS) method.

RESULTSThe expression of GFP gene was 31.4 % and 67.0 % with either hTERT promoter or CMV promoter in DLD1 cells; GFP/TRAIL gene was able to inhibit cell growth (74.2%) and induce apoptosis (25.8%) of HT-29 cells. There was significant difference between Ad/hTERT-gTRAIL and the other two control groups (PBS and Ad/CMV-GFP, P<0.05).

CONCLUSIONThe GFP/TRAIL gene with hTERT promoter transfected by adenoviral vector was successfully expressed in HT-29 cell, which can both inhibit cell growth and induce apoptosis of colon cancer cell line HT-29.

Adenoviridae ; genetics ; Apoptosis ; physiology ; Colonic Neoplasms ; enzymology ; pathology ; Genetic Vectors ; Green Fluorescent Proteins ; biosynthesis ; genetics ; HT29 Cells ; Humans ; Promoter Regions, Genetic ; genetics ; TNF-Related Apoptosis-Inducing Ligand ; biosynthesis ; genetics ; Telomerase ; genetics ; Tumor Cells, Cultured