Insulin-like growth factor binding protein-6 activates programmed cell death in non-small cell lung cancer cells

Insulin-like growth factor binding proteins (IGFBPs) are secreted into the extra-cellular matrix and inhibit cell growth through IGF-dependent and -independent mechanisms. In this study, we investigated the role of IGFBP-6, a relatively unexplored member of the IGFBP family, in the proliferation of non-small cell lung cancer (NSCLC) cells. Infection of NSCLC cell lines in vitro with an adenovirus expressing human IGFBP-6 under the control of a CMV promoter (Ad5CMV-BP6) reduced NSCLC cell number through activation of programmed cell death, as shown by cell staining with Hoechst 33342 or DNA end-labeling with bromodeoxyuridine triphosphate. The growth regulatory effect of IGFBP-6 was investigated in vivo by intratumoral injection of Ad5CMV-BP6 in NSCLC xenografts established in nu/nu mice. A single injection of Ad5CMV-BP6 reduced the size of NSCLC xenografts by 45%. These findings indicate that IGFBP-6 is a potent inducer of programmed cell death in cancer cells and support investigations into IGFBP-6 as a potential target in cancer therapeutics.     

Prognostic relevance of programmed cell death ligand 1 expression in glioblastoma

The aim of this study was to determine the clinicopathological significance of programmed cell death ligand 1 (PD-L1) expression in glioblastoma (GBM). In a retrospective cohort of 115 consecutive patients with GBM, PD-L1 expression was determined using immunohistochemistry (IHC). Membranous and fibrillary PD-L1 staining of any intensity in >?5% neoplastic cells and tumour infiltrating immune cells (TIIs) was considered positive staining. In addition, isocitrate dehydrogenase-1 (IDH-1) (R132H) expression and cluster of differentiation 3 (CD3)-positive T-cell infiltration were investigated using IHC. O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation assay and fluorescence in situ hybridization (FISH) for the assessment of 1p/19q deletion were performed. Expression of PD-L1 in tumour cells and TIIs was found in 37 (32.2%) and 6 (5.2%) patients, respectively. Kaplan–Meier analysis indicated that PD-L1 expression in tumour cells was significantly associated with poor overall survival (OS) (P?=?0.017), though multivariate Cox analysis did not confirm this association (hazard ratio 1.204; P?=?0.615). PD-L1 expression in TIIs did not correlate with the patient prognosis (P?=?0.545). In addition, MGMT methylation and IDH-1 (R132H) expression were associated with a better prognosis (P?<?0.001 and P?=?0.024, respectively). The expression of PD-L1 was associated with CD3-positive T-cell infiltration (P?<?0.001), and IDH-1 wild type status (P?=?0.008). A deeper insight into PD-L1 expression could help to ensure the success of future immunotherapy in GBM. Our study suggested that PD-L1 target therapy might be beneficial for PD-L1-expressing GBM patients with a poor prognosis.     

Gemcitabine induces programmed cell death and activates protein kinase C in BG-1 human ovarian cancer cells

Purpose: Cytosine arabinoside induces apoptosis and this cell death process is influenced by protein kinase C signaling events in leukemic cells. We present findings that extend these observations to include another deoxycytidine analog, gemcitabine, which is more potent in solid tumors. Methods and results: Gemcitabine induced programmed cell death in BG-1 human ovarian cancer cells based on biochemical and morphologic analyses. The DNA was fragmented in BG-1 cells exposed to gemcitabine (0.5 μM, 1.0 μM and 10 μM ) for 8 h, but gemcitabine treatment did not induce internucleosomal DNA degradation. Scanning and transmission electron microscopy of BG-1 cells showed morphologic changes associated with apoptosis in response to gemcitabine: membrane blebbing, the formation of apoptotic bodies and chromatin condensation. Thus, BG-1 cells undergo programmed cell death in response to gemcitabine treatment without internucleosomal DNA fragmentation. Furthermore, gemcitabine (10 μM) activated protein kinase C in BG-1 cells and the phosphorylation of the endogenous protein kinase C substrate, myristoylated alanine-rich C kinase substrate, was increased following exposure of BG-1 cells to gemcitabine for up to 6 h. Clonogenicity studies with gemcitabine in combination with various protein kinase C-modulating agents demonstrated that gemcitabine cytotoxicity was influenced by protein kinase C signaling events in BG-1 cells. Short-term (1 h) exposure to TPA (1 or 10 nM ) followed by gemcitabine (0.5 μM for 4 h) did not alter the response to gemcitabine. However, a 24-h exposure to TPA followed by gemcitabine resulted in synergistic cytotoxicity, while coincubation of TPA with a PKC inhibitor (e.g. bisindolylmaleimide or calphostin-C) in this regimen abrogated the synergistic response. Conclusions: Based on our findings, it is plausible that gemcitabine therapy could be improved by modulating PKC signaling events linked to drug-induced apoptosis/cytotoxicity. Received: 7 November 1996 / Accepted: 11 September 1997     

Down-regulation of programmed cell death 4 leads to epithelial to mesenchymal transition and promotes metastasis in mice

In this study, we demonstrated that knockdown of programmed cell death 4 (Pdcd4), a novel tumour suppressor, decreased the expressions of epithelial-specific proteins and increased the expressions of mesenchymal-specific proteins in vitro and in vivo, suggesting that knockdown of Pdcd4 results in epithelial to mesenchymal transition (EMT). Knockdown of Pdcd4 increased the rate of wound closure and migration capacity in wound-healing assays and Boyden chamber migration assays, respectively, indicating that Pdcd4 knockdown promotes cell migration. Pdcd4 knockdown also altered the adhesion capacity of GEO cells to extracellular matrix including laminin, collagen IV and fibronectin. To test whether knockdown of Pdcd4 promotes metastasis in vivo, parental, control and Pdcd4 knockdown cells were injected into the caecal wall (orthotopic implantation) of nude mice. Tumours are formed on caecum in all injected mice. However, only mice injected with Pdcd4 knockdown cells developed hepatic and local lymph node metastases. Immunohistochemical staining analyses showed that c-Myc and Snail/Slug expressions were up-regulated in the tumours derived from injection of Pdcd4 knockdown cells. These results implicated that promotion of metastasis by Pdcd4 knockdown was contributed by up-regulation of c-Myc and Snail/Slug in nude mice. Taken together, our data demonstrated that knockdown of Pdcd4 leads to EMT, alternation of adhesion and promotion of migration and metastasis.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

程序性细胞死亡因子10与肿瘤

程序性细胞死亡因子10(PDCD10)是一个在多种组织中保守表达的基因.研究表明,其具有细胞凋亡抑制功能及血管生成重建功能,且在多种肿瘤组织中表达明显上调,提示其可能在肿瘤的信号转导通路中起重要作用,并可能作为一个新的诊断肿瘤及预测预后的重要肿瘤学标志物应用于临床.     

Lanatoside C sensitizes glioblastoma cells to tumor necrosis factor-related apoptosis-inducing ligand and induces an alternative cell death pathway

Human glioblastoma (GBM) cells are notorious for their resistance to apoptosis-inducing therapeutics. We have identified lanatoside C as a sensitizer of GBM cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced cell death partly by upregulation of the death receptor 5. We show that lanatoside C sensitizes GBM cells to TRAIL-induced apoptosis in a GBM xenograft model in vivo. Lanatoside C on its own serves as a therapeutic agent against GBM by activating a caspase-independent cell death pathway. Cells treated with lanatoside C showed necrotic cell morphology with absence of caspase activation, low mitochondrial membrane potential, and early intracellular ATP depletion. In conclusion, lanatoside C sensitizes GBM cells to TRAIL-induced cell death and mitigates apoptosis resistance of glioblastoma cells by inducing an alternative cell death pathway. To our knowledge, this is one of the first examples of use of caspase-independent cell death inducers to trigger tumor regression in vivo. Activation of such mechanism may be a useful strategy to counter resistance of cancer cells to apoptosis.     

PDCD4基因在胶质瘤细胞系的稳定表达及其对肿瘤细胞生长的影响

目的:建立稳定表达程序性死亡4基因(programmed cell death 4, PDCD4)的人神经胶质瘤U251细胞系,观察PDCD4基因对人神经胶质瘤细胞增殖及细胞周期的影响.方法:将构建好的携带PDCD4重组真核表达载体pEGFP-PDCD4转染U251细胞,经过G418筛选获得稳定细胞系;用RT-PCR及Western blotting检测PDCD4 mRNA和蛋白的表达情况,通过锥虫蓝染色活细胞计数法及克隆形成实验检测外源PDCD4转染对细胞增殖和克隆形成能力的影响,以流式细胞术检测细胞周期.结果:成功建立稳定表达PDCD4的胶质瘤细胞U251-PDCD4.未转染的U251及空载体转染的U251细胞均不表达PDCD4,而pEGFP-PDCD4转染的U251-PDCD4细胞表达高水平的PDCD4 mRNA和蛋白质;转染PDCD4基因的细胞生长速度明显减慢(P<0.01)、克隆形成率明显降低(P<0.01);细胞周期检测显示,转染PDCD4的细胞较其他两对照组细胞S期升高、G2/M期明显降低(P<0.05).结论:PDCD4通过干扰细胞周期明显抑制胶质瘤U251细胞的细胞增殖及克隆形成能力.     

Activation of polyamine catabolism by N1,N11-diethylnorspermine leads to cell death in glioblastoma

Glioblastoma multiforme (GBM) is one of the most therapeutically refractory human cancers. Elevated cellular polyamine levels are a common feature of cancer cells, including GBM cells, and the polyamine pathway has been explored as a potential therapeutic target to inhibit polyamine biosynthesis or activate polyamine catabolism. In this study, we investigated the effect of N1,N11-diethyl-norspermine (DENSPM), a spermine analog that activates polyamine catabolism, in GBM cells. The in vitro cell culture experiments showed that DENSPM increased the sub-G1 apoptotic cell population in GBM cell lines but caused minimal cytotoxicity in normal astrocytes. Prior to apoptosis induction, DENSPM caused the elevation of spermidine/spermine N1-acetyltransferase (SSAT) expression accompanied by a decrease in polyamine levels and an increase of acetylated polyamine levels, which temporally coincided with the onset of hydrogen peroxide (H2O2) induction in the cells. The cytotoxic effects of DENSPM in the GBM cells could be partially attenuated by either turning down SSAT mRNA with small interference RNA or inhibiting H2O2 production with N1-acetylpolymine oxidase (APAO)/spermine oxidase (SMO) inhibitor. Though mitochondrial damage was induced, neither activation of the caspase cascade nor cytochrome c redistribution between the mitochondria and cytoplasm was observed. Systemic DENSPM treatment of mice with intracerebral GBM led to longer survival. Taken together, our studies indicate that DENSPM kills GBM cells through induction of SSAT coupled with H2O2 production, which is a potential target for GBM therapy.     

Cryptotanshinone activates p38/JNK and inhibits Erk1/2 leading to caspase-independent cell death in tumor cells

Cryptotanshinone (CPT), a natural compound isolated from the plant Salvia miltiorrhiza Bunge, is a potential anticancer agent. However, the underlying mechanism is not well understood. Here, we show that CPT induced caspase-independent cell death in human tumor cells (Rh30, DU145, and MCF-7). Besides downregulating antiapoptotic protein expression of survivin and Mcl-1, CPT increased phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-jun N-terminal kinase (JNK), and inhibited phosphorylation of extracellular signal-regulated kinases 1/2 (Erk1/2). Inhibition of p38 with SB202190 or JNK with SP600125 attenuated CPT-induced cell death. Similarly, silencing p38 or c-Jun also in part prevented CPT-induced cell death. In contrast, expression of constitutively active mitogen-activated protein kinase kinase 1 (MKK1) conferred resistance to CPT inhibition of Erk1/2 phosphorylation and induction of cell death. Furthermore, we found that all of these were attributed to CPT induction of reactive oxygen species (ROS). This is evidenced by the findings that CPT induced ROS in a concentration- and time-dependent manner; CPT induction of ROS was inhibited by N-acetyl-L-cysteine (NAC), a ROS scavenger; and NAC attenuated CPT activation of p38/JNK, inhibition of Erk1/2, and induction of cell death. The results suggested that CPT induction of ROS activates p38/JNK and inhibits Erk1/2, leading to caspase-independent cell death in tumor cells.