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

Expression of several molecular determinants of apoptosis was analyzed in 10 untreated small cell (SCLC) and 6 untreated non-small cell (NSCLC) lung carcinoma cell lines. Although SCLC lines were more prone to spontaneous apoptosis compared with NSCLC lines, the former showed higher Bcl-2 expression and a higher Bcl-2/Bax ratio. In order to understand this apparent contradiction, the expression of pro-caspases as well as calpain was analyzed in these cell lines at the protein and mRNA levels. No differences in protein level of pro-caspases-2, -3, -7, and -9 and of calpain were detected between the SCLC and the NSCLC lines, but a striking difference in pro-caspase-8 expression was noted. All 6 NSCLC, but only 2 of the 10 SCLC lines, expressed pro-caspase-8 protein. Further experiments using the RNase protection assay indicated that the lack of pro-caspase-8 expression at the mRNA level was characteristic for SCLC. Using the same experimental approach, we found that SCLC cell lines in addition to pro-caspase-8 were deficient in mRNA expression of pro-caspases-1, -4, and -10, suggesting a different caspase-activating cascade in SCLC compared with NSCLC. This first systematic characterization of pro-caspase expression in lung cancer surprisingly showed that SCLC, which are more prone to undergo spontaneous apoptosis, are deficient in several pro-caspases and have a high Bcl-2/Bax ratio. Thus, the propensity of SCLC cells to undergo apoptosis cannot be explained only by the expression of factors involved in regulation or execution of apoptosis.
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PMID:Differences in expression of pro-caspases in small cell and non-small cell lung carcinoma. 1046 84

The new chemotherapeutic agent, flavopiridol, presently in clinical trials, has been extensively studied yet little is known about its mechanism of action. In this study we show that the induction of apoptosis by flavopiridol is largely independent of Bcl-2. This is indicated by the observation that neither overexpression nor the antisense oligonucleotide-mediated down-regulation of Bcl-2 had any effect on flavopiridol-induced cell killing. Our results suggest that flavopiridol can induce apoptosis through different pathways of caspase activation with caspase 8 playing a pivotal role. In human lung carcinoma cells, which contain high levels of endogenous Bcl-2 and lack procaspase 8, flavopiridol treatment leads to mitochondrial depolarization in the absence of cytochrome c release, followed by the activation of caspase 3 and cell death. These results clearly differ from observations made with other anti-tumor drugs and might explain, at least in part, the unusual anti-tumor properties of flavopiridol.
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PMID:Bcl-2 independence of flavopiridol-induced apoptosis. Mitochondrial depolarization in the absence of cytochrome c release. 1089 73

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

Many anticancer drugs exert their cytotoxicity through DNA damage and induction of apoptosis. Small cell lung carcinoma (SCLC) and non-small cell lung carcinoma (NSCLC) have different sensitivity to treatment with radiation and chemotherapeutic agents with SCLC being more sensitive than NSCLC both in vitro and in vivo. This difference might be related to the different susceptibility of small and non-small cell lung carcinoma to undergo apoptosis. The aim of this study was to investigate if deficiencies in the apoptotic pathways can explain the intrinsic resistance of NSCLC to anti-cancer treatment. Three different triggers were used to induce apoptosis. Etoposide and gamma-radiation, which are important parts of clinical lung cancer treatment, induce DNA-damage, whereas Fas ligation induces receptor-mediated apoptotic pathways. NSCLC cells were cross-resistant to all treatments, whereas SCLC cells, which do not express pro-caspase-8, were resistant to alphaFas-, but not to DNA-damage-induced apoptosis. Cytochrome c release, activation of caspase-9 and the executioner caspase-3 were observed in both types of lung cancer cells. However, cleavage of known nuclear substrates for caspase-3, such as PARP and DFF45/ICAD, was documented only in the sensitive SCLC cells but not in the resistant NSCLC cells. Moreover, relocalization of active caspase-3 from the cytosol into the nucleus upon treatment was observed only in the SCLC cell line. These results indicate that the inhibition of apoptosis in NSCLC occurs downstream of mitochondrial changes and caspase activation, and upstream of nuclear events.
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PMID:Defective caspase-3 relocalization in non-small cell lung carcinoma. 1142 Jul

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

Discodermolide and epothilone B are promising novel chemotherapeutic agentsthat induce cell death through potent stabilization of microtubules. In this study, we investigated the cellular and molecular events underlying the cytotoxicity of these drugs in non-small cell lung carcinoma (NSCLC) cell lines, focusing on apoptotic characteristics. IC80 concentrations of either drug effectively disrupted the microtubule cytoskeleton of H460 cells and induced cell cycle disturbances with early accumulation in the G2-M phase and development of a hypodiploid cell population in both H460 and SW1573 cells. These events were followed by abnormal chromosome segregation during mitosis and subsequent appearance of multinucleated cells. At later time points, the cells displayed several apoptotic features, such as nuclear condensation and fragmentation as well as Annexin V staining, cleavage of poly(ADP-ribose) polymerase and the activation of caspases. To examine the contribution of apoptotic pathways to the cytotoxic effects of these agents, the involvement of the mitochondria and death receptor routes was studied. At 48 h after treatment, both agents disrupted mitochondria of H460 cells, as indicated by cytochrome c release. Nonetheless, H460 cells stably overexpressing antiapoptotic Bcl-2 or Bcl-xL did not show any protective effect from cell death induced by either drug. Possible death receptor dependency was investigated in H460 cells stably overexpressing dominant-negative FADD, which failed to reduce the cytotoxic effects of discodermolide and epothilone B. To study the role of caspases more directly, the effect of stable overexpression of the caspase-8 inhibitor cytokine response modifier A was studied in H460 cells. Furthermore, the effect of the pancaspase inhibitor z-Val-Ala-Asp-fluoromethyl ketone was investigated in a panel of lung carcinoma cell lines. Interestingly, caspase inhibition did not rescue cells from discodermolide or epothilone B-induced cell death. In conclusion, these results demonstrate that despite several apoptotic features detected at relatively late time points after drug exposure, apoptosis is not the dominant mode of cell death and induced low but efficacious concentrations of discodermolide and epothilone B.
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PMID:Late activation of apoptotic pathways plays a negligible role in mediating the cytotoxic effects of discodermolide and epothilone B in non-small cell lung cancer cells. 1212 45

Caspase-8 (CASP8) is an apoptosis inducing cysteine protease which is activated through the formation of a death-inducing signaling complex when death receptors are complexed to their specific ligands. Recent reports indicate that CASP8 expression is lost via a combination of promoter methylation and allelic loss in subset of neuroblastomas. We investigated the state of the gene in lung tumors and cell lines. RT-PCR studies indicated that gene expression was lost in most (27 of 34, 79%) of small cell lung carcinoma (SCLC) cell lines, but expression was retained in all 22 non-SCLC (NSCLC) lines tested. Loss of gene expression at the RNA level was associated with absent protein expression by Western blotting and lack of CASP8 enzymatic activity. Methylation of the promoter region of the CASP8 gene was present in 16 of 27 (59%) of the SCLC lines lacking gene expression. All methylated cell lines lacked the presence of an unmethylated allele indicating biallelic methylation or loss of non-methylated allele. Promoter methylation was absent in all SCLC and NSCLC cell lines retaining gene expression, and all of these lines had the unmethylated form of the gene. One non-expressing SCLC cell line, NCI-H82, had a homozygous deletion at 2q33 encompassing the chromosomal location of the CASP8 gene. The mechanism of gene inactivation in the remaining 10 of 27 (37%) non-expressing SCLC cell lines is unknown. Using five polymorphic markers for 2q33 a high frequency of allelic loss was present in SCLC lines. Analyses of fresh tumors showed that 15 of 43 (35%) of the SCLC, seven of 40 (18%) of bronchial carcinoids and none of 44 NSCLC tumors had CASP8 promoter methylation. Because only approximately 60% of SCLC cell lines lacking CASP8 expression were methylated, extrapolating from the cell line data, we estimate that approximately 58% of SCLC and 30% of bronchial carcinoids lack CASP8 expression. Thus, CASP8 expression is absent in a subset of both high grade (SCLC) and low grade (carcinoid) neuroendocrine lung tumors but not in NSCLC, which usually lack neuroendocrine features. CASP8 may function as a tumor suppressor gene in neuroendocrine lung tumors.
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PMID:Differential inactivation of caspase-8 in lung cancers. 2430 54

Flavopiridol is one of the first cyclin-dependent kinase inhibitors undergoing clinical tests. We found that the combination treatment of flavopiridol (100-500 nM) with tumor necrosis factor (TNF)-alpha (10 ng/ml) induced a rapid and eminent apoptosis, 20 +/- 5% in 6-h treatment, in a human non-small cell lung carcinoma cell line, A549, as determined by the increase of sub-G(1) fraction in flow cytometry. A similar observation was also made in human colon cancer cell lines, HCT-116 and HCT-15, but not in Rat2, a rat fibroblast cell line. In A549 cells, the cytotoxic synergy by the combination treatment involved the activation of caspase-1, caspase-3, and caspase-8 and generated huge chromosomal degradation. The treatment schedules were so important that only the treatments of flavopiridol concomitantly with or followed by TNF-alpha showed the pronounced apoptosis in A549 cells. Prior treatment of TNF-alpha inhibited the apoptosis by the following combination treatment, leading to little cell death. Yet, such inhibition was reversed when 100 microM of 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, a transcription inhibitor, was present during the TNF-alpha pretreatment, suggesting that the inhibitory pretreatment of TNF-alpha might involve antiapoptotic gene expression at the transcriptional level. TNF-alpha treatment resulted in nuclear factor (NF)-kappa B activation, revealed by NF-kappa B activity reporter assay. In contrast, flavopiridol was found to inhibit the NF-kappa B-dependent gene transcription, which might give an explanation for the synergistic effect of flavopiridol with TNF-alpha. TNF-related apoptosis-inducing ligand (TRAIL; 100 ng/ml) also caused a rapid and strong cytotoxic synergy with flavopiridol. In contrast to TNF-alpha, however, all of the treatment sequences supported the synergy by TRAIL and flavopiridol. The combination of flavopiridol with TNF-alpha or TRAIL may be of use for the development in cancer therapy.
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PMID:Rapid induction of apoptosis by combination of flavopiridol and tumor necrosis factor (TNF)-alpha or TNF-related apoptosis-inducing ligand in human cancer cell lines. 1256 5

Apoptosis could be measured in mammalian cells by measuring the degradation of the small cytoplasmic human RNA Y1 (hY1) by real-time quantitative fluorescent reverse transcriptase polymerase chain reaction (RT-PCR). In FAS-antibody-treated Jurkat T cell leukemia cells degradation of hY1 occurred rapidly and was complete at about 6h. As in apoptotic Jurkat cells, protein synthesis is arrested only after about 12h; this implies that protein synthesis can occur without scRNA-Y1. The degradation of hY1 could be blocked with peptide-based inhibitors of caspase 8 and with lower efficacy with caspases 1 and 3 and with ZnSO4. No effects were observed after inhibition of caspases 2, 6, and 9. Degradation of hY1 could also be demonstrated after treatment of A549 lung carcinoma cells treated with Staurosporin, Paclitaxel, or the histone deacetylase inhibitor LAQ824. RT-PCR systems based on SYBR Green, Amplifluor Uniprimer, or 5' nuclease Taqman could be used with increasing sensitivity. This apoptosis assay requires quantities of total cell RNA equivalent to only a few tissue culture cells and is especially suited to measure apoptosis in projects where RNA samples are already available from gene expression studies.
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PMID:Rapid detection of apoptosis through real-time reverse transcriptase polymerase chain reaction measurement of the small cytoplasmic RNA Y1. 1281 25

Parathyroid hormone-related protein (PTHrP) is expressed in more advanced, aggressive tumors and may play an active role in cancer progression. This study investigated the effects of PTHrP on apoptosis after UV irradiation, Fas ligation, or staurosporine treatment in BEN human squamous lung carcinoma cells. Cells at 70% confluency were treated for 24 h with 100 nM PTHrP-(1-34), PTHrP-(38-64), PTHrP-(67-86), PTHrP-(107-139), or PTHrP-(140-173) in media with serum, exposed for 30 min to UV-B radiation (0.9 mJ/cm2), and maintained for another 24 h. Caspase-3, caspase-8, and caspase-9 activities increased fivefold. Pretreatment with PTHrP-(1-34) and PTHrP-(140-173) ameliorated apoptosis after UV irradiation, as indicated by reduced caspase activities, increased cell protein, decreased nuclear condensation, and increased clonal survival. Other peptides had no effect on measures of apoptosis. PTHrP-(140-173) also reduced caspase activities after Fas ligation by activating antibody, but neither peptide had effects on caspase-3 or caspase-9 activity after 1 microM staurosporine. These data indicate that PTHrP-(1-34) and PTHrP-(140-173) protect against death receptor-induced apoptosis in BEN lung cancer cells but are ineffective against mitochondrial pathways. PTHrP contributes to lung cancer cell survival in culture and could promote cancer progression in vivo. The mechanism for the protective effect against apoptosis remains to be determined.
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PMID:Parathyroid hormone-related protein ameliorates death receptor-mediated apoptosis in lung cancer cells. 1291 4


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