Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:5.99.1.2 (topoisomerase)
9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Patterns of drug sensitivities in relation to topoisomerase II gene expression and activity were studied in eight human lung cancer cell lines not selected in vitro for drug resistance. The cytotoxicities of doxorubicin, etoposide, teniposide, cisplatin, camptothecin, and 5-fluorouracil were measured and, remarkably, these unselected cell lines were shown to have a common pattern of multidrug sensitivity, i.e., a multidrug sensitivity phenotype. In fact, drug sensitivities were significantly correlated with each other in the studied cell lines, the correlation being best for the topoisomerase II-targeted agents and cisplatin, less strong with camptothecin, and weak with 5-fluorouracil. Almost 1-log range difference of topoisomerase II gene expression was found in these cell lines, and this was not explained by the cell-doubling time or cell cycle distribution. The level of topoisomerase II gene expression was positively and highly correlated with the cell sensitivity to epipodophyllotoxins, doxorubicin, and cisplatin in seven cell lines. Although weaker, an association was also observed between topoisomerase II gene expression and camptothecin cytotoxicity, while no association was observed with 5-fluorouracil. However, a non-small cell lung cancer cell line with neuroendocrine properties had very low levels of expression of the topoisomerase II gene, despite being highly sensitive to all drugs tested. The levels of topoisomerase I gene expression were not found to be correlated with the cytotoxicity of any drug tested. A specific enzymatic activity assay and a teniposide-stimulated DNA cleavage assay showed that the extent of active topoisomerase II present in nuclear extracts paralleled the level of topoisomerase II gene expression. Furthermore, in addition to the normal transcript, an abnormally sized topoisomerase II message and a rearrangement of the topoisomerase II gene were detected in a poorly sensitive small cell lung cancer cell line. Therefore, low levels of topoisomerase II gene expression, and possibly mutations, may predict a reduced sensitivity of unselected human lung cancer cell lines to several drugs, including agents with a cellular target other than topoisomerase II. It is hypothesized that topoisomerase II might be involved in a common pathway of cell death induced by drugs in tumor cell lines which present a multidrug sensitivity phenotype.
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PMID:Multidrug sensitivity phenotype of human lung cancer cells associated with topoisomerase II expression. 131 95

This article describes the current approach to the systematic management of both small cell and non-small cell lung cancer (NSCLC). The treatment of stages I, II, and IIIa NSCLC is surgical resection. Although adjuvant chemotherapy in stage I disease offers no survival benefit, the role of adjuvant chemotherapy in stage II and IIIa NSCLC remains controversial. Results of pilot studies using neoadjuvant chemotherapy in stage IIIa NSCLC are encouraging and data from ongoing randomized trials are awaited with interest. For locally advanced NSCLC, chest irradiation remains the standard of care. However, the addition of systemic chemotherapy holds promise. The impact of cisplatin-based regimens on overall survival in stage IV NSCLC remains disappointing. The introduction of newer agents, such as 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11), a topoisomerase-I inhibitor, has shown early favorable results. Chemotherapy is the most important therapeutic modality in the management of small cell lung cancer because of this cancer's propensity for early dissemination. In limited stage small cell lung cancer, chest radiotherapy, particularly if used early and concurrently with chemotherapy, may improve survival, but at the expense of increased toxicity. The role of prophylactic brain irradiation remains controversial in limited-stage disease. Chemotherapy is also the most important treatment modality in extensive-stage disease, but its role is only palliative. Radiotherapy is reserved primarily for disease-related complications in patients in whom chemotherapy has failed.
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PMID:Lung cancer: a review of current therapeutic modalities. 132 79

We investigated the interaction between human lung cancer cells, laminin, and several differentiating agents. When grown on laminin coated substrate eight out of 11 small cell lung cancer (SCLC) cell lines exhibited attachment to laminin and three had extensive outgrowth of long neurite-like processes. Of seven non-small cell lung cancer cell lines, selected for their in vitro anchorage-independent growth, attachment was observed in only three cell lines, and process formation was far less extensive than in SCLC cell lines. Among several differentiating agents, only dcAMP, which alone induced attachment and some process formation, increased laminin-mediated attachment and process formation of two SCLC cell lines, NCI-N417 a variant cell line, and NCI-H345, a classic cell line. The expression of several neuroendocrine and neuronal markers was investigated in these two SCLC cell lines. The expression of the light subunit of neurofilaments increased in NCI-N417 within 3 to 4 days of seeding, while NCI-H345 exhibited approximately 5 fold increase in expression of the GRP gene and a 3 fold increase expression of the beta-actin gene. The expression of a number of other neuroendocrine and neuronal markers did not change following growth on laminin. The doubling times remained unchanged independent of the presence of and attachment to laminin while topoisomerase II gene expression levels in NCI-N417 cells decreased approximately 5 fold when cells were growing on laminin.
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PMID:Increased expression of differentiation markers can accompany laminin-induced attachment of small cell lung cancer cells. 132 26

Etoposide remains an integral component of therapy for non-small cell lung cancer. Its single-agent activity, and, hence, its activity in combination therapy, need to be reassessed in light of several reports of increased activity at higher doses. Although no effective means of overcoming resistance to etoposide appear to exist, topoisomerase II levels may predict sensitivity to treatment. Biologic response modifiers appear to add little or nothing to standard etoposide chemotherapy for non-small cell lung cancer. Continuous low-dose etoposide infusions do not appear to exhibit the same degree of activity as has been observed with prolonged oral dosing. The availability of effective means of reducing hematologic and emetic side effects of chemotherapy may permit rational trials of more intensive therapy.
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PMID:The role of standard-dose etoposide in the management of non-small cell lung cancer. 133 19

CI-921 (NSC 343499; 9-[[2-methoxy-4-[(methylsulphonyl)amino]phenyl]amino] -N,5-dimethyl- 4-acridinecarboxamide) is a topoisomerase II poison with high experimental antitumour activity. It was administered by 15 min infusion to 16 evaluable patients with non-small cell lung cancer (NSCLC) (7 with no prior treatment, 9 patients in relapse following surgery/radiotherapy) at a dose (648 mg/m2 divided over 3 days, repeated every 3 weeks) determined by phase I trial. Patients had a median performance status of 1 (WHO), and median age of 61 years. The histology comprised squamous carcinoma (11), adenocarcinoma (1), mixed histology (2), bronchio-alveolar carcinoma (1) and large cell undifferentiated carcinoma (1). Neutropenia grade greater than or equal to 3 was seen in 15 patients, infections with recovery in 3, and grand mal seizures in 1 patient. Grade less than or equal to 2 nausea and vomiting occurred in 66% courses and phlebitis in the infusion arm in 37%. 1 patient with squamous cell carcinoma achieved a partial response lasting 5 months. Further testing in this and other tumour types using multiple daily schedules is warranted.
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PMID:Phase II study of the amsacrine analogue CI-921 (NSC 343499) in non-small cell lung cancer. 166 18

Etoposide is a phase-specific, schedule-dependent derivative of podophyllotoxin that appears to act by inhibiting DNA-topoisomerase II. Early preclinical work demonstrated sharp activity in mouse leukemias and possible synergy with cisplatin. As a single agent (either orally or intravenously), it demonstrated limited benefit in non-small cell lung cancer (NSCLC), with response rates around 10%. In combination with cisplatin, it has become a mainstay of chemotherapeutic efforts, either as primary therapy or in conjunction with radiation. Response rates in advanced disease average around 30%, climbing to more than 50% in patients with Stage IIIA or IIIB disease. More recent work suggests that the issue of the true synergy of etoposide with cisplatin in NSCLC needs reassessment. The relative roles of etoposide and cisplatin in the combination are unclear, as several studies conflict. Pharmacokinetic data suggest that multiple daily fractions of etoposide are superior to prolonged infusions, warranting several future trials. The current major role for etoposide plus cisplatin would appear to be in multimodality therapy where the combination can be readily combined with radiation and/or surgery. Several other agents have been studied with etoposide or etoposide plus cisplatin (mitomycin, vindesine, doxorubicin, cyclophosphamide, ifosfamide, and carboplatin), but it is unclear whether the addition of any of them offers any response or survival advantage.
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PMID:Etoposide in the management of non-small cell lung cancer. 184 48

The lamins, an intranuclear class of intermediate filament proteins, are major structural proteins of the nuclear envelope. In the present study, the three abundant mammalian lamins (lamins A, B, and C) were observed to be present in roughly equivalent amounts in the Calu-1, Calu-3, H157, and SK-MES-1 non-small cell lung cancer lines. In the small cell lung cancer lines OH-1, OH-3, NCI-H82, NCI-H209, and NCI-H249, levels of lamin B were similar to those observed in the non-small cell lines, but the levels of lamins A and C were diminished by greater than or equal to 80%. The relationship between lung cancer phenotype and lamin expression was explored further in the NCI-H249 small cell line. Introduction of the v-rasH oncogene into this line gives rise to a cell line (NCI-H249rasH) with many features of large cell carcinoma of the lung (Falco, J. P., Baylin, S. B., Lupu, R., et al. J. Clin. Invest., 85: 1740-1745, 1990). Concomitant with the v-rasH-induced change in phenotype, a greater than 10-fold increase in the amounts of lamins A and C was observed. Levels of the cytoplasmic intermediate filament protein vimentin also increased. In contrast, levels of a variety of nonlamin nuclear polypeptides including topoisomerase I, topoisomerase II, poly(ADP-ribose) polymerase, and the nucleolar protein B23/nucleophosmin did not change. Comparison of polyadenylated RNA from NCI-H249 and NCI-H249rasH cells on Northern blots revealed similar levels of the mRNA for lamin B but higher levels of the mRNAs for lamins A and C in the v-rasH-expressing cell line. These observations provide evidence for differences in nuclear envelope structure in histologically different neoplastic cells derived from the same epithelial cell system and suggest that differences in lamina structure result from phenotype-specific differences in lamin gene expression.
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PMID:Differential expression of nuclear envelope lamins A and C in human lung cancer cell lines. 198 76

Studies have suggested that recombinant tumor necrosis factor-alpha (TNF-alpha) may potentiate the killing of murine tumor cells by drugs targeted at DNA topoisomerase II. We have examined the combined cytotoxic effects of the topoisomerase-targeted drug etoposide and TNF in small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) cell lines using clonogenic assays and a novel flow cytometry technique relying on differential uptake of fluorescein diacetate (FDA) and propidium iodide (PI) by viable and nonviable cells. Good correlation of IC50 determinations for etoposide were noted between clonogenic assays and the FDA/PI technique for both classic and variant SCLC cell lines. The effects of etoposide on the classic SCLC line H209 were potentiated by TNF with a decrease in the IC50 from 3.3 microM to 1.0 microM as determined by FDA/PI. Tumor necrosis factor alone had little effect on the growth or cloning efficiency of H209 cells. Tumor necrosis factor alone stimulated the growth and cloning of variant SCLC line N417, but the cytotoxicity of etoposide was not potentiated by TNF in N417 cells. Tumor necrosis factor alone inhibited the growth and cloning of the NSCLC line H125 but exerted a marked protective effect against higher concentrations of etoposide. It appears that the interaction of TNF with etoposide varies between cell lines and between subclasses of human lung cancer.
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PMID:Interaction of recombinant human tumor necrosis factor and etoposide in human lung cancer cell lines. 217 61

Suramin cytotoxicity was studied in a panel of human lung cancer cell lines by the MTT assay. The concentrations of suramin which induced 50% growth inhibition (IC50) ranged from 130 to 3715 microM for the cell lines growing in medium containing 10% fetal calf serum (FCS). In only one cell line was the IC50 at a concentration that can be reached in plasma of patients treated with suramin. Suramin was 18 and 3.3 times more cytotoxic on NCI-N417 cells growing in 2% FCS and in HITES serum-free medium, respectively, than growing in 10% FCS. No difference in suramin cytotoxicity was observed between small and non-small cell lung cancer cell lines. At the lower concentrations tested, suramin stimulated proliferation of the two small cell lung cancer cell lines, NCI-H187 and NCI-N417. Of several growth factors tested, none induced stimulation of growth in NCI-H187 and NCI-N417 cell lines, nor did they in any way alter the stimulatory effect of suramin. Cell counting, DNA flow cytometric analysis and Ki-67 staining confirmed a higher proliferative state in suramin-exposed NCI-H187 cells as compared with untreated cells. However, topoisomerase II-alpha gene expression remained unchanged, as assessed by northern blot analysis and immunostaining. Suramin had an inhibitory effect on topoisomerase II activity, as assessed by the kDNA decatenation assay, with an IC50 of approximately 40 microM. In conclusion, suramin has significant cytotoxic activity in a minority of human lung cancer cell lines, and it stimulates proliferation in some instances. The pleiotropic action of suramin observed should caution on the possibility of tumour acceleration in patients being treated with this drug.
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PMID:Effects of suramin on human lung cancer cell lines. 771 32

Topoisomerase II protein is essential for cell proliferation and is known to exist as a phosphoprotein in cells from both lower and higher eukaryotic species. In this paper, we have investigated the phosphorylation of the alpha isozyme of human topoisomerase II. The topoisomerase II alpha protein was phosphorylated predominantly on serine residues in the human tumor cell lines HeLa and NSCLC-3. Two-dimensional tryptic phosphopeptide mapping studies revealed several sites of phosphorylation in vivo, including a major site that was common to topoisomerase II alpha protein from both HeLa and NSCLC-3 cells. To identify sites of phosphorylation, the regulatory C-terminal domain of human topoisomerase II alpha protein was overexpressed in Escherichia coli as a hexahistidine-tagged fusion protein and purified by nickel chelate chromatography. Tryptic phosphopeptide mapping revealed that casein kinase II phosphorylated the C-terminal domain primarily on 2 serine residues in vitro, which were shown to be sites of modification in vivo. Site-directed mutagenesis studies identified these casein kinase II-specific phosphorylation sites as serine 1524 and serine 1376.
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PMID:Serine 1524 is a major site of phosphorylation on human topoisomerase II alpha protein in vivo and is a substrate for casein kinase II in vitro. 796 67


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