Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0684249 (lung carcinoma)
 23,830 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have identified the CD95 system as a key mediator of chemotherapy-induced apoptosis in leukemia and neuroblastoma cells. Here, we report that sensitivity of various solid tumor cell lines for drug-induced cell death corresponds to activation of the CD95 system. Upon drug treatment, strong induction of CD95 ligand (CD95-L) and caspase activity were found in chemosensitive tumor cells (Hodgkin, Ewing's sarcoma, colon carcinoma and small cell lung carcinoma) but not in tumor cells which responded poorly to drug treatment (breast carcinoma and renal cell carcinoma). Blockade of CD95 using F(ab')2 anti-CD95 antibody fragments markedly reduced drug-induced apoptosis, suggesting that drug-triggered apoptosis depended on CD95-L/receptor interaction. Moreover, drug treatment induced CD95 expression, thereby increasing sensitivity for CD95-induced apoptosis. Drug-induced apoptosis critically depended on activation of caspases (ICE/Ced-3-like proteases) since the broad-spectrum inhibitor of caspases zVAD-fmk strongly reduced drug-mediated apoptosis. The prototype substrate of caspases, poly(ADP-ribose) polymerase, was cleaved upon drug treatment, suggesting that CD95-L triggered autocrine/paracrine death via activation of caspases. Our data suggest that chemosensitivity of solid tumor cells depends on intact apoptosis pathways involving activation of the CD95 system and processing of caspases. Our findings may have important implications for new treatment approaches to increase sensitivity and to overcome resistance of solid tumors.
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PMID:Chemosensitivity of solid tumor cells in vitro is related to activation of the CD95 system. 953 69

CTL and NK cells use two distinct cytocidal pathways: 1) perforin and granzyme based and 2) CD95L/CD95 mediated. The former requires perforin expression by the effectors (CTL or NK), whereas the latter requires CD95 (Fas/APO-1) expression by the target. We have investigated how these two factors contribute to tumor immune surveillance by studying the immunity of perforin-deficient mice against the progressor C57BL/6 Lewis lung carcinoma 3LL, which expresses no CD95 when cultured in vitro. Unexpectedly, the results indicated that the perforin-independent CD95L/CD95 pathway of CTL/NK plays a role in acting against D122 and Kb39.5 (39.5) high and low metastatic sublines, respectively, derived from the 3LL tumor. Although no membrane-bound CD95 was detected on cultured D122 and 39. 5 cells, surface CD95 expression on both D122 and 39.5 was considerably up-regulated when the tumors were grown in vivo. A similarly enhanced expression of CD95 was observed with three additional tumors; LF-, BW, and P815, injected into syngeneic and allogeneic mice. The finding of up-regulated CD95 expression on tumor cells placed in vivo suggests that a CD95-based mechanism plays a role in tumor immunity at early stages of tumor growth. Consequently, the progressive down-regulation of CD95 expression during tumor progression may indeed be an escape mechanism as previously reported. Together, these results suggest a role for CD95-dependent, perforin-independent immunity against certain tumors.
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PMID:Tumor immunity in perforin-deficient mice: a role for CD95 (Fas/APO-1). 1070 15

We have isolated a cytotoxic T lymphocyte (CTL) clone, Heu161, that reacts specifically with the human autologous lung carcinoma cell line IGR-Heu. We first demonstrated that IGR-Heu lacked Fas-receptor expression and was resistant to CD95-induced apoptosis. To further elucidate the role of Fas in tumor immune surveillance, we have stably transfected IGR-Heu with a Fas-expression vector and isolated CD95-sensitive and -resistant clones. Our data indicated that the resistance of 2 selected Fas-transfected clones to CD95-mediated lysis correlated with down-regulation of caspase-8 or its lack of cleavage and subsequent activation. All Fas transfectants, either sensitive or resistant to anti-Fas agonistic antibody, were as efficiently lysed by the CTL clone as the parental cell line. In addition, neither anti-Fas-blocking antibody nor Fas-Fc molecule inhibited T-cell lysis of Fas-sensitive tumor clone. This cytotoxicity was extracellular Ca(2+)-dependent and abolished in the presence of EGTA, indicating that it was mainly granzyme-mediated. Interestingly, although the caspase inhibitor z-VAD-fmk had no effect on tumor-cell lysis, it efficiently blocked target DNA damage triggered by autologous CTLs via the granule exocytosis pathway, indicating that the latter event was caspase-dependent. The present results suggest that lung carcinoma-specific CTLs use mainly a granule exocytosis-dependent pathway to lyse autologous target cells and that these effectors are able to circumvent alteration of the Fas-triggered intracellular signalling pathway via activation of a caspase-independent cytoplasmic death mechanism.
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PMID:Role of Fas and granule exocytosis pathways in tumor-infiltrating T lymphocyte-induced apoptosis of autologous human lung-carcinoma cells. 1127 78

To understand the function of the individual oncogenes of HPV16 in modulating the cellular response to apoptogenic signals, we used human keratinocytes immortalized with either E6, E7 or E6/E7 oncoproteins as model system. Applying CD95 antibodies or recombinant CD95 ligand, only the E7-immortalized cells underwent extensive apoptosis. In contrast, E6- and E6/E7-expressing keratinocytes were resistant. Dominance of E6 correlated with significant down-regulation of p53, c-Myc, p21 and Bcl-2. CD95 was found to be reduced in resistant HPV-positive cells, while there were no quantitative differences in expression levels of FADD, FLICE/caspase-8 or caspase-3. Notably, in contrast to primary human keratinocytes, all immortalized cells showed a general reduction of c-FLIP, an inhibitory protein which normally prevents unscheduled CD95-induced apoptosis. E6- and E6/E7-positive keratinocytes, however, can be sensitized to CD95 apoptosis by blocking proteasome-mediated proteolysis. CD95-resistant HPV-positive cells underwent apoptosis within 3-5 h upon co-incubation with MG132 and agonistic antibodies or CD95 ligand, which was preceded by a strong re-expression of p53 and c-Myc, but not of other half-life controlled proteins such as Bax or IkappaBalpha. Blockage of proteasomal activity alone did not result in apoptosis, although the same set of pro-apoptotic proteins was up-regulated. Performing similar experiments with cervical carcinoma cells expressing mutated p53 (C33a) or with p53-'null' lung carcinoma cells (H1299), no CD95 cell killing occurred even though c-Myc was strongly induced. These data indicate that the reduced bioavailability of p53 is a key-regulatory event in perturbation of CD95 signaling in HPV16 immortalized keratinocytes.
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PMID:Restoration of p53 expression sensitizes human papillomavirus type 16 immortalized human keratinocytes to CD95-mediated apoptosis. 1180 60

Non-small cell lung cancer (NSCLC) is a malignant tumor with poor prognosis. Although the prognostic variables determining short-term survival have been well described, relatively little attention has been paid to factors associated with long-term survival. In search of these factors we studied the expression of several molecular markers in NSCLC. Only tumor samples of patients with squamous cell carcinomas and stage III tumors with a postoperative survival of at least 5 years and those of patients who died within 2 years after resection were selected for this study. The expression of several parameters including oncogene and suppressor gene products, proliferative, apoptotic, angiogenic and resistance-related factors were investigated and the differences in these two extreme populations were determined by the Wilcoxon rank sum test. Factors involved in proliferation (ras, fos, erbB-1, jun, cyclin A) were downregulated whereas factors involved in apoptosis (p53, bcl-2, CD95) were upregulated in the long survival group. Direct measurement of parameters of proliferation (cell cycle analysis by flow cytometry, PCNA index) revealed a lower proliferative activity in tumors of the long survivors compared to short survivors. In conclusion, tumors of the long survival group are characterized by a downregulation of factors involved in proliferation and an upregulation of factors involved in apoptosis. These tumors may grow more slowly and this may influence long-term survival of patients with NSCLC.
Lung Cancer 2002 Jun
PMID:Characteristics of long-term survivors of untreated lung cancer. 1200 38

Inactivation of p53 has been implicated in many types of tumors particularly in non-small cell lung carcinoma, one of the most common cancers in which p53 mutation has been frequently identified. The aim of this study was to investigate the influence of p53 status on the regulation of tumor susceptibility to specific CTL-mediated cell death. For this purpose, we used a cytotoxic T lymphocyte clone, Heu127, able to lyse the human autologous lung carcinoma cell line, IGR-Heu, in a HLA-A2-restricted manner. Direct genomic DNA sequencing revealed that IGR-Heu expresses a mutated p53 at codon 132 of the exon 5 which results in the loss of p53 capacity to induce the expression of the p53-regulated gene product p21(waf/CIP1). Initial experiments demonstrated that IGR-Heu was resistant to Fas, TNF, and TRAIL apoptotic pathways. This correlated with the lack of p55 TNFRI, Fas, DR4, and DR5 expression. The effect of wild-type (wt) p53 restoration on the sensitization of IGR-Heu to autologous CTL clone lysis was investigated following infection of the tumor cell line with a recombinant adenovirus encoding the wt p53 (Adwtp53). We demonstrate that the restoration of wt p53 expression and function resulted in a significant potentiation of target cell susceptibility to CTL-mediated lysis. The wt p53-induced optimization of tumor cell killing by specific CTL involves at least in part Fas-mediated pathway via induction of CD95 expression by tumor cells but does not appear to interfere with granzyme B cytotoxic pathway.
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PMID:Potentiation of a tumor cell susceptibility to autologous CTL killing by restoration of wild-type p53 function. 1279 18

Fas (CD95) and its ligand FasL signal apoptosis and are involved in tissue homeostasis and the elimination of target cells by cytotoxic T cells. Corruption of this signalling pathway in tumour cells, for example by reduced Fas expression or increased FasL expression, can participate in tumour development and immune escape. The present study has analysed Fas/FasL expression and Fas death signalling function in vivo in lung tumour tissues [57 non-small cell lung carcinomas and 64 neuroendocrine lung tumours including small cell lung carcinoma (SCLC)] in comparison with normal lung tissue, and in vitro in neuroendocrine tumour cell lines in comparison with normal human bronchial epithelial cells. The Fas expression score was markedly decreased compared with normal lung tissue in 90% of the 121 lung tumours and was completely lost in 24%. The Fas staining pattern suggested cytoplasmic Fas expression in tumours, whereas membrane expression was observed in normal lung tissue. Loss of Fas at the cell surface was also shown in vitro by FACS analysis of neuroendocrine tumour cell lines and was concomitant with the resistance of tumour cells to FasL-mediated apoptosis according to in vitro cell viability. The lack of cell surface Fas expression in tumour cell lines resulted from the lack of intracellular Fas protein due to impaired Fas gene transcription. The FasL expression score was also decreased in most non-small cell lung carcinomas compared with normal bronchial cells, whereas 91% of SCLCs had higher expression than normal cells. FasL overexpression was related to advanced tumour stage as well as to a Fas/FasL ratio less than 1. It is concluded that a marked decrease in Fas expression may be part of lung tumourigenesis allowing tumour cells to escape from apoptosis. FasL overexpression in the context of Fas down-regulation in SCLC predicts the ability of SCLC cells to induce paracrine killing of Fas-expressing cytotoxic T cells. In lung tumours, Fas restoration may represent a key, although not unique, step in therapeutic strategies to reconstitute the ability of tumour cells to undergo apoptosis.
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PMID:Frequent loss of Fas expression and function in human lung tumours with overexpression of FasL in small cell lung carcinoma. 1451 44

Non small cell lung carcinoma (NSCLC) is a highly lethal malignancy that often becomes resistant to chemotherapy. To determine whether alterations in apoptotic signaling might contribute to such resistance, we established in vitro and in vivo models for sensitive and resistant human NSCLC. We found that resistance is due to multiple defects found in expression of CD95-L, CD95 and members of the Bcl-2 and IAP family, as well as caspase-8, -9 and -3 as examined by immunohistochemistry, Western blot analysis, gene array analysis and functional assays. Failure to activate death receptor, as well as mitochondrial apoptosis signaling, points to a central role of caspases. To restore apoptosis signaling we transfected NSCLC xenografts on nude mice with caspase-8 and -9. This treatment strongly induced apoptosis per se and sensitized the tumors to cisplatin-induced cell death. Thus, these findings indicate that re-expression of caspases might be an effective strategy to restore sensitivity for chemotherapy in NSCLC in vivo.
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PMID:Rescue of death receptor and mitochondrial apoptosis signaling in resistant human NSCLC in vivo. 1469 23

In this study, we have investigated the mechanisms used by wild-type p53 (wtp53) to potentiate tumor cell susceptibility to CTL-mediated cell death. We report that wtp53 restoration in a human lung carcinoma cell line Institut Gustave Roussy (IGR)-Heu, displaying a mutated p53, resulted in up-regulation of Fas/CD95 receptor expression associated with an increase of tumor cell sensitivity to the autologous CTL clone, Heu127. However, when IGR-Heu cells were transfected with Fas cDNA, no potentiation to Heu127-mediated lysis was observed, indicating that induction of CD95 is not sufficient to sensitize target cells to CTL killing. Importantly, our data indicate that the effect of wtp53 on the Fas-mediated pathway involves a degradation of short cellular FLICE inhibitory protein resulting in subsequent caspase 8 activation. Furthermore, we demonstrate that wtp53 restoration also resulted in CTL-induced Bid translocation into mitochondria and a subsequent mitochondrial membrane permeabilization leading to cytochrome c release. These results indicate that tumor cell killing by autologous CTL can be enhanced by targeting degranulation-independent mechanisms via restoration of wtp53, a key determinant of apoptotic machinery regulation.
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PMID:p53 potentiation of tumor cell susceptibility to CTL involves Fas and mitochondrial pathways. 1563 9

Synthetic alkyl-lysophospholipids represent a family of promising anticancer drugs that induce apoptosis in a variety of tumor cells. Here we have found a differential subcellular distribution of the alkyl-lysophospholipid edelfosine in leukemic and solid tumor cells that leads to distinct anticancer responses. Edelfosine induced rapid apoptosis in human leukemic cells, including acute T-cell leukemia Jurkat and Peer cells, but promoted a late apoptotic response, preceded by G(2)/M arrest, in human solid tumor cells such as cervix epitheloid carcinoma HeLa cells and lung carcinoma A549 cells. c-Jun amino-terminal kinase (JNK) and caspase-3 were accordingly activated at earlier times in edelfosine-treated Jurkat cells as compared with drug-treated HeLa cells. Both leukemic and solid tumor cells took up this alkyl-lysophospholipid and expressed the two putative edelfosine targets, namely cell surface Fas death receptor (also known as APO-1 or CD95) and endoplasmic reticulum CTP: phosphocholine cytidylyltransferase. However, edelfosine was mainly located to plasma membrane lipid rafts in Jurkat and Peer leukemic cells and to endoplasmic reticulum in solid tumor HeLa and A549 cells. Edelfosine induced translocation of Fas, Fas-associated death domain-containing protein, and JNK into membrane rafts in Jurkat cells, but not in HeLa cells. In contrast, edelfosine inhibited phosphatidylcholine biosynthesis in both HeLa and A549 cells, but not in Jurkat or Peer leukemic cells, before the triggering of apoptosis. These data indicate that edelfosine targets two different subcellular structures in a cell type-dependent manner, namely cell surface lipid rafts in leukemic cells and endoplasmic reticulum in solid tumor cells.
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PMID:Differential targets and subcellular localization of antitumor alkyl-lysophospholipid in leukemic versus solid tumor cells. 1654 Apr 73


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