Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.99.1.2 (topoisomerase)
 9,166 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The human KIN17 protein is a chromatin-associated protein involved in DNA replication. Certain tumor cell lines overproduce KIN17 protein. Among 16 cell lines, the highest KIN17 protein level was observed in H1299 non-small cell lung cancer cells, whereas the lowest was detected in MeWo melanoma cells. Cells displaying higher KIN17 protein levels exhibited elevated RPA70 protein contents. High KIN17 protein levels may be a consequence of the tumorigenic phenotype or a prerequisite for tumor progression. Twenty-four hours after exposure to ionizing radiation, after the completion of DNA repair, a co-induction of chromatin-bound KIN17 and RPA70 proteins was detected. Etoposide, an inhibitor of topoisomerase II generating double-strand breaks, triggered the concentration of KIN17 into punctuate intranuclear foci. KIN17 may be associated with unrepaired DNA sites. Flow cytometry analysis revealed that 48 h after transfection the uppermost KIN17-positive RKO cells shifted in the cell cycle toward higher DNA content, suggesting that KIN17 protein induced defects in chromatin conformation. Cells displaying reduced levels of KIN17 transcript exhibited a sixfold increased radiosensitivity at 2 Gy. The KIN17 protein may be a component of the DNA replication machinery that participates in the cellular response to unrepaired DSBs, and an impaired KIN17 pathway leads to an increased sensitivity to ionizing radiation.
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PMID:Depletion of KIN17, a human DNA replication protein, increases the radiosensitivity of RKO cells. 1275 57

Patients with non-small cell lung cancer (NSCLC) typically receive platinum-based combination chemotherapy. In spite of improvements in symptoms and survival, response rates remain low and newer agents are being investigated. The newer agents may offer increased efficacy and reduced toxicity compared with established agents and regimens. The topoisomerase-I inhibitor, topotecan, achieves single-agent response rates of 4-25% in NSCLC. Topotecan has also been studied in combinations: a combination of topotecan, administered using the standard 5-day schedule, with cisplatin was effective but was associated with myelosuppression. The combination of topotecan plus carboplatin may be better tolerated and warrants further investigation. Topotecan was also combined with newer agents (gemcitabine, vinorelbine, docetaxel, paclitaxel) using a range of different administration schedules of topotecan. Response rates of up to 30% were achieved. A weekly schedule of topotecan was effective and well tolerated and was also convenient for healthcare professionals and patients.
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PMID:Combination chemotherapy with topotecan for non-small cell lung cancer. 1456 11

Cisplatin or carboplatin is commonly used with gemcitabine, docetaxel, paclitaxel or vinorelbine as chemotherapy doublets in the treatment of advanced non-small cell lung cancer. Several randomized trials have failed to identify major differences in survival between any of these doublets. This lack of evidence for improvement in survival with any chemotherapy regimen has created a tabula rasa in which no more large randomized trials should be conducted with out including a genetic analysis. Patients see survival as their major concern, and other considerations, such as cost of treatment and qualify of life, are relegated to lower positions. Genetic alterations related to the transcription-coupled repair pathway of the nucleotide excision repair system (TC-NER) have revealed the subset of patients who are resistant to cisplatin. TC-NER involves genes that are deficient in rare inborn disorders such as Cockayne syndrome and xeroderma pigmentosum. For a long time, ERCC1 mRNA levels have been known to correlate with DNA repair capacity in various tissues. Levels of DNA cisplatin adducts in peripheral blood and buccal mucosa cells predict chemotherapy response, and high ERCC1 mRNA levels have been related to chemoresistance in ovarian cancer and in malignant lymphocytes from chronic lymphocytic leukemia. Moreover , in some instances, mRNA expression has been correlated with polymorphisms. Overexpression of ERCC1 correlates with poor survival gemcitabine/cisplatin-treated non-small cell lung cancer patients. An ongoing customized ERCC1-based chemotherapy trial has been established on this knowledge. Patients are randomized to the control arm of cisplatin/docetaxel is combined with cisplatin or gemcitabine according to ERCC1 levels. To date, 80 patients have been included. At the preclinical level, ERCC1 and XPD mRNA expression correlate with each other, and overexpression of XPD causes selective cisplatin resistance in human tumor cell lines. Some XPD polymorphisms have been associated with lower DNA repair capacity. In our experience, time to disease progression is significantly higher in gemcitabine/cisplatin-treated patients with the Lys751Gln genotype (9.6 months) than in those with the Lys751Lys genotype (4.2 months; p = 0.03). Other polymorphisms involved in parallel DNA repair systems may well provide the same information, indicating a high degree of biological redundancy. The overexpression of the subunit M1 of ribonucleotide reductase (RRM1) has been linked to gemcitabine resistance in our retrospective assessment. Preliminary findings indicate that a subset of gemcitabine/cisplatin-treated patients with low ERCC1 and RRM1 mRNA levels show a significantly longer survival. This highlights the possibilities of individually tailored chemotherapy. However, in patients treated with cisplatin/vinorelbine, the opposite effect has been observed. Patients with Lys751Lys had a longer time to progression. When docetaxel was added to gemcitabine/cisplatin, patients with Lys751Lys also had better survival. Our findings indicate that TC-NER status can help to decide between cisplatin/gemcitabine and docetaxel/ cisplatin. TC-NER-dependent activity is similar to other anticancer agents that cause DNA-binding enzymes to kill cells (topoisomerase inhibitors). At least 50% of non-small cell lung cancer patients harbor Lys751Lys and can benefit from docetaxel/ cisplatin treatment. Genes involved in spindle formation, centrosome functions and mRNA transport along the microtubule tracks should provide further information on potential markers of docetaxel resistance.
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PMID:Influence of genetic markers on survival in non-small cell lung cancer. 1466 33

Etoposide is an antitumor agent currently in clinical use for the treatment of small cell lung cancer, testicular cancer and lymphomas. Since the introduction of etoposide in 1971, its mechanism of action and potent antineoplastic activity has served as the impetus for intensive research activities in chemistry and biology. This drug acts by stabilizing a normally transient DNA-topoisomerase II complex, thus increasing the concentration of double-stranded DNA breaks. This phenomenon triggers mutagenic and cell death pathways. The function of topoisomerase II is understood in some detail, as is the mechanism of inhibition of etoposide at a molecular level. Etoposide has shortcomings of limited neoplastic activity against several solid tumors such as non-small cell lung cancer, cross-resistance to MDR tumor cell lines and low bioavailability. The design and synthesis of etoposide analogs is an activity of fundamental interest to the field of cancer chemotherapy. In the first part, this article is a survey of the discovery of etoposide, the DNA topoisomerase II structure and mechanism, and the models for drug-enzyme interaction. The last part is concerned with the search for new etoposide analogs based upon an empirical design.
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PMID:Etoposide: discovery and medicinal chemistry. 1537 7

Chronic myelomonocytic leukaemia (CMML) is a preleukaemic condition with myeloproliferative features, and classified as a part of myelodysplastic syndrome (MDS). Other than alkylating agents and topoisomerase II inhibitors, there is less evidence that chemotherapeutic drugs are associated with therapy-related CMML, acute leukaemia or MDS. We present a patient who developed CMML within 2 years of platinum-based chemotherapy for a metastatic non-small cell lung cancer. He received a cumulative dose of 240 mg/m(2) of cisplatin, and 1123 mg/m(2) of carboplatin before developing CMML. The cytogenetic study revealed trisomy 8. This is the first reported case that links platinum-based therapy with development of CMML with trisomy 8. Although the relationship between platinum therapy and the development of CMML is difficult to assess due to combinational nature of therapy in most cases, physicians should consider the possibility of CMML in patients with symptoms or signs suggestive of haematologic malignancy after platinum therapy.
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PMID:Chronic myelomonocytic leukaemia after platinum-based therapy for non-small cell lung cancer: case report and review of the literature. 1688 13

Her2 and topoisomerase-IIalpha (T2A) gene amplification are separate events, although the latter is more frequently seen in Her2 amplified (34-90%) than in Her2 non-amplified (5-10%) tumours. There is a better correlation between Her2 amplification and protein overexpression in breast cancer (BC) than in other tumour types. This marker is also considered a powerful prognostic factor in BC, with similar data emerging in other solid tumours such as bladder, ovarian, endometrial, gastro-oesophageal and non-small cell lung cancer. Her2 amplification and/or overexpression are highly predictive of response to HER2-targeted compounds such as trastuzumab and lapatinib but have been inconsistent predictors of response to cytotoxic chemotherapy. There is also evidence that these tumours are relatively resistant to anti-oestrogen therapy (tamoxifen) but not to oestrogen deprivation (e.g. with aromatase inhibitors). T2A aberrations are uncommon events in solid tumours, with an overall prevalence of approximately 10%. T2A amplification has shown inconsistent correlation with T2A protein expression in preclinical and clinical studies, mainly because non-genetic events such as proliferation rate can also affect protein expression. Expression of T2A protein has not been shown to reliably predict response to T2A inhibitors, despite the fact that this enzyme is the direct target for these compounds. In BC, T2A amplification appears to be a good predictor of response to anthracyclines, but these data are still in the process of validation. The significance of T2A deletions is currently under investigation, but contrary to what was previously thought, it may also predict benefit from treatment with T2A inhibitors. The prognostic significance of T2A aberrations is currently unknown.
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PMID:The 17q12-q21 amplicon: Her2 and topoisomerase-IIalpha and their importance to the biology of solid tumours. 1711 34

Lung cancer is the leading cause of cancer deaths among both males and females. Although there have been several advances in the treatment armamentarium, both small cell and nonsmall cell lung cancer continue to be prognostically poor diseases that are refractory to therapy. Several of the regimens involved in treating the disease include drugs that inhibit the topoisomerase enzymes, whose specific role in relieving torsional strain on DNA to facilitate replication and transcription has long been known. Topoisomerase inhibition, however, has increasingly gained attention because of its efficacy in disease stabilization in lung cancer, with continued elaboration of its exact mechanism in lung cancer therapy. This review presents the biology and molecular mechanics of the topoisomerase enzymes, as well as the effect of their inhibition in SCLC and NSCLC, with discussion of specific drugs and the data to support and explain its use as a chemotherapeutic target in lung cancer.
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PMID:A review of topoisomerase inhibition in lung cancer. 1722 34

Amrubicin is a totally synthetic anthracycline anticancer drug and a potent topoisomerase II inhibitor. Recently, amrubicin was approved in Japan for the treatment of small- and non-small-cell lung cancers (SCLC and NSCLC). Here, we review the efficacy and toxicities of amrubicin monotherapy and amrubicin in combination with cisplatin for extensive-disease SCLC (ED-SCLC), and of amrubicin monotherapy for advanced NSCLC, as observed in the clinical trials. Recommended dosage for previously untreated advanced NCSLC was 45 mg/m2/day by intravenous administration for 3 days. Dose-limiting toxicities were leucopenia, thrombocytopenia, and gastrointestinal disturbance. Response rate was 27.9% for advanced NSCLC, and 75.8% for ED-SCLC with a median survival time (MST) of 11.7 months. Recommended dosage of amrubicin was 40 mg/m2/day in combination with cisplatin at 60 mg/m2/day, with MST of 13.6 months and 1-year survival rate of 56.1%. In sensitive or refractory relapsed SCLC, response rate was 52 and 50%, progression-free survival was 4.2 and 2.6 months, overall survival was 11.6 and 10.3 months, and 1-year survival rate was 46 and 40%, respectively. These results are promising for the treatment of both NSCLC and SCLC. Further clinical trials will clarify the status of amrubicin in the treatment of lung cancer.
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PMID:Amrubicin for non-small-cell lung cancer and small-cell lung cancer. 1762 45

Amonafide (1), a naphthalimide which binds to DNA by intercalation and poisons topoisomerase IIalpha, has demonstrated activity in phase II breast cancer trials, but has failed thus far to enter clinical phase III because of dose-limiting bone marrow toxicity. Compound 17 (one of 41 new compounds synthesized) is a novel anticancer naphthalimide with a distinct mechanism of action, notably inducing autophagy and senescence in cancer cells. Compound 17 (2,2,2-trichloro-N-({2-[2-(dimethylamino)ethyl]-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-5-yl}carbamoyl)acetamide (UNBS3157)) was found to have a 3-4-fold higher maximum tolerated dose compared to amonafide and not to provoke hematotoxicity in mice at doses that display significant antitumor effects. Furthermore, 17 has shown itself to be superior to amonafide in vivo in models of (i) L1210 murine leukemia, (ii) MXT-HI murine mammary adenocarcinoma, and (iii) orthotopic models of human A549 NSCLC and BxPC3 pancreatic cancer. Compound 17, therefore, merits further investigation as a potential anticancer agent.
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PMID:2,2,2-Trichloro-N-({2-[2-(dimethylamino)ethyl]-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin- 5-yl}carbamoyl)acetamide (UNBS3157), a novel nonhematotoxic naphthalimide derivative with potent antitumor activity. 1765 77

Anthracyclines and anthracenediones are well-known cancer chemotherapeutic agents but their uses are limited with cardiotoxicity and drug resistance. Several l- and d-form amino acids were introduced into the anthraquinone skeleton and numerous derivatives were synthesized for the evaluation of anticancer activity. The screening tests showed that WRC-213, an l-methionine conjugation, was the most effective derivative to inhibit proliferative effect of human androgen-independent prostate cancer PC-3 cells (IC50=50 nM). In an extension evaluation, WRC-213 displayed a potent anti-proliferative activity in various cancer cell lines, including non-small cell lung cancer A549, androgen-independent prostate cancer DU145, colorectal cancer HT-29, breast cancer MCF-7 and hepatocellular carcinoma Hep3B and HepG2. It induced cell-cycle arrest at S and G2, but not mitotic phase, in PC-3 cells. The comet assay revealed that induction of DNA damage and inhibition of topoisomerase II were the primary insults. After the checkpoint arrest of the cell-cycle, WRC-213 induced the mitochondria-mediated intrinsic apoptotic pathway, including Mcl-1 cleavage, Bcl-2 down-regulation and activation of caspase-9/caspase-3 cascades. Survivin degradation and caspase-2 activation also contributed to WRC-213-induced apoptosis. Moreover, the assessment of cytotoxicity in H9c2 cardiomyocytes and drug resistance in NCI/ADR-RES cells demonstrated that WRC-213 showed much lower cardiotoxicity and P-glycoprotein-related resistance than those of mitoxantrone, etoposide and doxorubicin. In conclusion, it is suggested that WRC-213 is a potential topoisomerase II inhibitor with reduced cardiotoxicity and drug resistance. It inhibits topoisomerase II activity and induces chromosomal DNA strand breaks, leading to S and G2 arrest of the cell-cycle and activation of mitochondria-mediated apoptotic pathways.
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PMID:WRC-213, an l-methionine-conjugated mitoxantrone derivative, displays anticancer activity with reduced cardiotoxicity and drug resistance: identification of topoisomerase II inhibition and apoptotic machinery in prostate cancers. 1803 33


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