Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P42574 (caspase-3)
 45,978 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumour recurrence following chemotherapy remains a major obstacle to the cure of many cancers. This is exemplified by small-cell lung cancer (SCLC). Host-tumour interactions are central to tumour survival and proliferation. We hypothesized that a factor(s) within the local environment of SCLC cells could provide a survival signal or block a death signal, thereby accounting for the protection of SCLC cells from chemotherapy-induced apoptosis. Here we review recent work undertaken in our laboratory addressing this issue. We have shown that, in vivo, SCLC cells are surrounded by an extensive stroma of extracellular matrix (ECM) at both primary and metastatic sites which contains, among other proteins, fibronectin, laminin and collagen IV. Furthermore, adhesion of SCLC cells to fibronectin, laminin and collagen IV through beta1 integrins enhances tumorigenicity and confers resistance to apoptosis induced by standard chemotherapeutic agents, including etoposide, cis-platinum and adriamycin. Adhesion to ECM proteins stimulated protein tyrosine kinase (PTK) activity in both untreated and etoposide-treated cells. This effect could be completely blocked by a selective PTK inhibitor or by a function-blocking beta1 integrin antibody. PTK activation was found to block chemotherapy-induced activation of the death protease caspase-3 and, hence, apoptosis. Adhesion to ECM or treatment with a PTK inhibitor did not affect etoposide inhibition of topoisomerase II. Thus adhesion to ECM through beta1 integrins protects SCLC cells from chemotherapy-induced caspase-3 activation and apoptosis by activating PTK signalling downstream of DNA damage. Survival of tumour cells attached to ECM within this microenvironment could explain the local recurrence of SCLC and other tumours that is often seen clinically after chemotherapy.
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PMID:Extracellular matrix regulation of drug resistance in small-cell lung cancer. 1191 4

Apo2L/TRAIL exhibits enhanced apoptotic activity in tumor xenograft models when used in combination with the topoisomerase 1 inhibitor CPT-11. To investigate the cellular mechanisms involved in this increased tumor-killing activity, a series of in vitro experiments were conducted using the human colon carcinoma cell line (HCT116). Apo2L/TRAIL induced a transient upregulation of DR5 mRNA, while CPT-11 increased both death and decoy receptor expression. Upregulation of decoy receptors by CPT-11 was partially inhibited by co-administration of Apo2L/TRAIL. CPT-11 treatment resulted in accumulation of cells at G(2)M-phase and correlated with a substantial increase in the protein levels of the cyclin-dependent kinase inhibitor p21. However, cells co-treated with CPT-11 and Apo2L/TRAIL, or pretreated with CPT-11 for up to 24 h followed by 2 h Apo2L/TRAIL, resulted in a caspase-dependent degradation of p21, reversal of G(2)-M phase arrest with a concomitant increase in apoptosis. The sequential treatment produced the greatest induction of DR5 and DR4, caspase-3-like cleavage/activation and p21 degradation, as well as increased apoptosis. These data indicate that the up-regulation of Apo2L/TRAIL ligand and its death receptors as well as cleavage of p21 protein in the Apo2L/TRAIL plus CPT-11 treatment contributes to the positive cooperation between these agents in enhancing tumor cell apoptosis.
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PMID:Enhanced tumor killing by Apo2L/TRAIL and CPT-11 co-treatment is associated with p21 cleavage and differential regulation of Apo2L/TRAIL ligand and its receptors. 1203 63

We have isolated two overlapping genomic clones that contain the 5'-terminal portion of the human vacuolar H(+)-ATPase c subunit (ATP6L) gene. The sequence preceding the transcription initiation site, which is GC-rich, contains four GC boxes and one Oct1-binding site, but there is no TATA box or CCAAT box. In vivo footprint analysis in human cancer cells shows that two GC boxes and the Oct1-binding site are occupied by Sp1 and Oct1, respectively. We show here that treatment with anticancer agents enhances ATP6L expression. Although cisplatin did not induce ATP6L promoter activity, it altered ATP6L mRNA stability. On the other hand, the DNA topoisomerase II inhibitor, TAS-103, strongly induced promoter activity, and this effect was completely eradicated when a mutation was introduced into the Oct1-binding site. Treatment with TAS-103 increased the levels of both Sp1/Sp3 and Oct1 in nuclear extracts. Cooperative binding of Sp1 and Oct1 to the promoter is required for promoter activation by TAS-103. Incubation of a labeled oligonucleotide probe encompassing the -73/-68 GC box and -64/-57 Oct1-binding site with a nuclear extract from drug-treated KB cells yielded higher levels of the specific DNA-protein complex than an extract of untreated cells. Thus, the two transcription factors, Sp1 and Oct1 interact, in an adaptive response to DNA damage, by up-regulating expression of the vacuolar H(+)-ATPase genes. Furthermore, combination of the vacuolar H(+)-ATPase (V-ATPase) inhibitor, bafilomycin A1, with TAS-103 enhanced apoptosis of KB cells with an associated increase in caspase-3 activity. Our data suggest that the induction of V-ATPase expression is an anti-apoptotic defense, and V-ATPase inhibitors in combination with low-dose anticancer agents may provide a new therapeutic approach.
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PMID:Enhanced expression of the human vacuolar H+-ATPase c subunit gene (ATP6L) in response to anticancer agents. 1213 27

We here report the influence of the cell cycle abrogator UCN-01 on RKO human colon carcinoma cells differing in p53 status following exposure to two DNA damaging agents, the topoisomerase inhibitors etoposide and camptothecin. Cells were treated with the two drugs at the IC90 concentration for 24 h followed by post-incubation in drug-free medium. RKO cells expressing wild-type, functional p53 arrested the cell cycle progression in both the G1 and G2 phases of the cell cycle whereas the RKO/E6 cells, which lack functional p53, only arrested in the G2 phase. Growth-arrested cells did not resume proliferation even after prolonged incubation in drug-free medium (up to 96 h). To evaluate the importance of the cell cycle arrest on cellular survival, a non-toxic dose of UCN-01 (100 nM) was added to the growth-arrested cells. The addition of UCN-01 was accompanied by mitotic entry as revealed by the appearance of condensed chromatin and the MPM-2 phosphoepitope, which is characteristic for mitotic cells. G2 exit and mitotic transit was accompanied by a rapid activation of caspase-3 and apoptotic cell death. The influence of UCN-01 on the long-term cytotoxic effects of the two drugs was also determined. Unexpectedly, abrogation of the G2 arrest had no influence on the overall cytotoxicity of either drug. In contrast, addition of UCN-01 to cisplatin-treated RKO and RKO/E6 cells greatly increased the cytotoxic effects of the alkylating agent. These results strongly suggest that even prolonged cell cycle arrest in the G2 phase of the cell cycle is not necessarily coupled to efficient DNA repair and enhanced cellular survival as generally believed.
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PMID:Influence of G2 arrest on the cytotoxicity of DNA topoisomerase inhibitors toward human carcinoma cells with different p53 status. 1213 30

Salvicine is a novel topoisomerase II inhibitor possessing significant antitumor activity, both in vitro and in vivo. The antitumor effect of salvicine is associated with its ability to induce tumor cell apoptosis. Telomerase plays an important role in the apoptotic pathway. However, little is known about the mechanisms of telomerase regulation during apoptosis induced by anticancer drugs. This study investigated the regulation of telomerase activity in salvicine-induced human leukemia HL-60 cell apoptosis. Salvicine treatment resulted in HL-60 cell apoptosis and down-regulation of telomerase activity in a time- and concentration-dependent manner. Repression of telomerase activity preceded a decrease in expression of the telomerase catalytic subunit (hTERT) and telomerase-associated protein (TP1) at the mRNA level, suggesting that the salvicine-induced decrease in telomerase activity may be additionally regulated by mechanisms other than telomerase subunit transcription. We observed that okadaic acid (OA), a protein phosphatase inhibitor, prevented the induction of apoptosis and the down-regulation of telomerase activity by salvicine. The significant increase in protein phosphatase 2A (PP2A) activity induced by salvicine treatment was blocked completely by OA. Moreover, although salvicine induced HL-60 cell apoptosis in a caspase-3-dependent manner, a specific caspase-3 inhibitor, Z-DEVD-FMK, did not prevent a decrease in telomerase activity or an increase in PP2A activity in apoptotic HL-60 cells, ruling out a role for caspase-3 in PP2A activation by salvicine. The results collectively suggest that the salvicine-induced decline in telomerase activity is not a consequence of HL-60 cell apoptosis and that it may be caused principally by the dephosphorylation of telomerase components mediated by PP2A activation.
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PMID:Down-regulation of telomerase activity via protein phosphatase 2A activation in salvicine-induced human leukemia HL-60 cell apoptosis. 1244 57

DNA damage is believed to be the main cause of the antiproliferative effect of cisplatin, a cornerstone agent in anticancer therapy. However, cisplatin can be expected to react also with nucleophiles other than DNA. Using enucleated cells (cytoplasts) we demonstrate here that cisplatin-induced apoptotic signaling may occur independently of DNA damage. Cisplatin-induced caspase-3 activation in cytoplasts required calcium and the activity of the calcium-dependent protease calpain. It is known that calpain activation may be associated with endoplasmic reticulum (ER) stress, suggesting that the ER is a cytosolic target of cisplatin. Consistent with this hypothesis, cisplatin induced calpain-dependent activation of the ER-specific caspase-12 in cytoplasts as well as in intact cells. Cisplatin also induced increased expression of Grp78/BiP, another marker of ER stress. By contrast, the DNA-damaging topoisomerase II inhibitor etoposide did not induce apoptotic signaling in cytoplasts nor ER stress in intact cells. We have thus identified a novel mechanism of action of cisplatin. The results have implications for the understanding of resistance mechanisms as well as the unique efficiency of this drug.
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PMID:Cisplatin induces endoplasmic reticulum stress and nucleus-independent apoptotic signaling. 1250 15

FK506, a calcineurin inhibitor, shows potent neuroprotective effects in animal models such as those of stroke and neurodegenerative diseases. However, the mechanism underlying these neuroprotective effects is unclear. In this study, an in vitro model, in which FK506 protected the cells against cell death, was established and analyzed in detail by pharmacological experiments. Thapsigargin (TG), an inhibitor of endoplasmic reticulum calcium-ATPase, induced SH-SY5Y cell death. FK506 concentration-dependently protected the cells from this type of death. In contrast, FK506 did not suppress SH-SY5Y cell death caused by the following molecules: tunicamycin (TM), an inhibitor of N-linked glycosylation; etoposide (Eto), a topoisomerase II inhibitor; and staurosporine (STS), a phospholipid/calcium-dependent protein kinase inhibitor. Additionally, FK506 did not inhibit TG-induced cell death in either SK-N-MC or HeLa cell lines. FK506 completely inhibited caspase-3 activation and apoptosis caused by TG in a concentration-dependent manner, but not that caused by TM, Eto, and STS. TG did not activate caspase-3 in SK-N-MC cells, although it slightly activated caspase-3 in HeLa cells. FK506 did not change caspase-3 activity in either SK-N-MC or HeLa cell lines. Cyclosporin A, another calcineurin inhibitor, showed the same results as FK506 in this study, whereas rapamycin, an immunosuppressant not associated with calcineurin activity, did not have any effect in this context. Thus, the suppressive effects of FK506 on cell death are specific to SH-SY5Y cells treated with TG and are caused by the inhibition of calcineurin and subsequent suppression of caspase-3 activation. Therefore, an in vitro system using SH-SY5Y cells treated with TG could provide a model reflective of certain aspects of the neuroprotective activity of FK506.
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PMID:Detailed in vitro pharmacological analysis of FK506-induced neuroprotection. 1287 56

Because the aberrantly activated phosphoinositide 3-kinase (PI3K)/Akt pathway renders tumor cells resistant to cytotoxic insults, including those related to anticancer drugs, inhibition of the pathway may possibly restore or augment the effectiveness of chemotherapy. Using the human malignant glioma cell lines U87, A172, LN18, and LN229, we examined effects of the PI3K inhibitor LY294002 on both apoptosis and cytotoxicity induced by chemotherapeutic agents, including antimicrotubule agents vincristine and paclitaxel, an alkylating agent 1,3-bis(2-chloroethyl)-1-nitrosourea, a topoisomerase II inhibitor etoposide, and a DNA cross-linking agent cisplatin (cis-diamminedichloroplatinum), and we compared the LY294002-induced enhancement of effects of those agents. Ten to 20 micro M LY294002 augmented both apoptosis and caspase 3-like activity caused by antimicrotubule agents to a larger extent than induced by 1,3-bis(2-chloroethyl)-1-nitrosourea, etoposide, and cisplatin in all four malignant glioma cell lines examined. The same doses of LY294002 enhanced cytotoxicity more efficiently with antimicrotubule agents than with other chemotherapeutic agents. Quantitative analyses using a modified isobologram and median effect plot method revealed that enhancement by LY294002 of vincristine- or paclitaxel-induced cytotoxicity was synergistic, whereas enhancement by the PI3K inhibitor of the other chemotherapeutic agent-induced cytotoxicity was additive. Our study indicates that the synergistic augmentation of the cytotoxicity by LY294002 occurs specifically with antimicrotubule agents, at least partially through an increase in caspase 3-dependent apoptosis, and we suggest that inhibitors of the PI3K/Akt pathway in combination with antimicrotubule agents may induce cell death effectively and be a potent modality to treat patients with malignant gliomas.
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PMID:Synergistic augmentation of antimicrotubule agent-induced cytotoxicity by a phosphoinositide 3-kinase inhibitor in human malignant glioma cells. 1287 4

After several weeks of treatment, levels of alanine aminotransferase (ALT) increase in 50% of patients treated with tacrine for Alzheimer's disease. We looked for progressive effects on DNA to explain delayed toxicity. We first studied the in vitro effects of tacrine on DNA replication and topoisomerase-mediated DNA relaxation. We then treated mice with doses of tacrine reproducing the human daily dose on a body area basis and studied the effects of tacrine administration for up to 28 days on hepatic DNA, mitochondrial function, and cell death. In vitro, tacrine impaired DNA polymerase gamma-mediated DNA replication and also poisoned topoisomerases I and II to increase the relaxation of a supercoiled plasmid. In vivo, administration of tacrine markedly decreased incorporation of [(3)H]thymidine into mitochondrial DNA (mtDNA), progressively and severely depleted mtDNA, and partly unwound supercoiled mtDNA into circular mtDNA. Incorporation of [(3)H]thymidine into nuclear DNA (nDNA) was barely decreased, and nDNA levels were unchanged. After 12 to 28 days of treatment, administration of tacrine increased p53, Bax, mitochondrial permeability transition, cytosolic cytochrome c, and caspase-3 activity and triggered hepatocyte apoptosis and/or necrosis. In conclusion, the intercalating drug tacrine poisons topoisomerases and impairs DNA synthesis. Tacrine has been shown to accumulate within mitochondria, and it particularly targets mtDNA. After several weeks of treatment, the combination of severe mtDNA depletion and a genotoxic stress enhancing p53, Bax, and permeability transition trigger hepatocyte necrosis and/or apoptosis.
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PMID:Tacrine inhibits topoisomerases and DNA synthesis to cause mitochondrial DNA depletion and apoptosis in mouse liver. 1293 98

The correlation between the histological features and clinical outcome remains poor in pediatric intracranial ependymomas. We performed a retrospective study of a group of 31 patients (diagnosed from 1985 to 1995) to assess prognostic implications of the current grading system, of histological and immunohistochemical features, and of ploidy status estimated by flow cytometry. Immunoexpression of a broad spectrum of antigens was evaluated, including MIB-1, topoisomerase-IIalpha, cyclin D1, glial and epithelial proteins (GFAP, EMA, cytokeratins), molecules involved in controlling apoptosis (bcl-2, caspase-3/CPP32), and p53 oncoprotein. Univariate and multivariate statistical analyses were performed to evaluate the influence of each variable on both the progression free survival (PFS) and the overall survival (OS) with at least 7-year follow up. Although we showed a significant correlation between histological grade and prognosis, the current grading system failed in predicting outcome in nearly one third of individual cases. Problems with interpathologist reproducibility were also demonstrated. The extent of surgical resection was the only clinical factor that was associated with survival. Both the PFS and the OS were significantly decreased for the following pathological variables: increased cellularity (>300 nuclei per HPF), mitotic activity of >7 per 10 HPF, increased MIB-1 labeling index (LI), topoisomerase-IIalpha LI, S-phase fraction, and p53 and bcl-2 positivity. Increased cyclin D1 LI was demonstrated to have only a marginally significant impact on PFS. A flow chart modeling was further performed to formulate a scheme for discriminating of prognostic subgroups. Based on that, p53 immunopositivity and/or MIB-1 LI of >5% (after subtotal resection) or MIB-1 LI of >15% (after complete resection) were the strongest indicators of the tumor's aggressive behavior and of a poor prognosis of the disease. Foci of hypercellularity should be specifically looked for in ependymomas for assessing the immunohistochemical studies.
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PMID:Pediatric intracranial ependymomas: prognostic relevance of histological, immunohistochemical, and flow cytometric factors. 1455 80


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