Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0242379 (lung cancer)
 71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The efficacy of radiotherapy in locally advanced non-small-cell lung cancer is limited. One attempt to improve survival uses a combination of radiation and chemotherapy. These two modalities can be applied in sequence or concurrently, but results from phase III trials of combined therapy versus radiation alone have been inconsistent. Early studies were mostly negative, but more recent trials using platinum-based regimens have shown some survival benefit for combined treatments. The positive impact of chemotherapy has also been shown in a meta-analysis. In recent studies, concurrent chemotherapy and radiation appears better than sequential application. However, the benefit of the combined approach is modest and should be balanced against increased early and late toxicity. The role of new agents such as taxanes, vinorelbine, gemcitabine, and topoisomerase inhibitors in combined modality therapy of non-small-cell lung cancer warrants further clinical investigation.
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PMID:Combined chemotherapy and radiation in locally advanced non-small-cell lung cancer. 1190 49

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

Tryprostatin A 1 and B 2 are indole alkaloid-based fungal products that act in the G2/M phase of the cell cycle. Tryprostatin A and B as well as their two enantiomers and four diastereomers have been synthesized via a common strategy. As a measure of cytotoxicity, these eight stereoisomers were assayed for their growth inhibitory properties in human breast, prostate, and lung cancer cell lines. The ability of the tryprostatins and the tryprostatin stereoisomers to induce topoisomerase II-mediated DNA relaxation or to inhibit tubulin polymerization was also examined. Although none of the stereoisomers were significantly active in topoisomerase II- or tubulin-based assays, ds2-try B 11 was found to exhibit a cytotoxicity profile more potent than etoposide 3 in the human cancer cell lines examined. In addition, ds2-try B 11 is comprised of an L-tryptophan derivative coupled to a D-proline moiety, the latter stereochemistry of which may enhance the activity of 11 and potential analogues in vivo.
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PMID:Biological activity of the tryprostatins and their diastereomers on human carcinoma cell lines. 1193 9

The DNA topoisomerase inhibitor irinotecan (CPT-11, Camptosar) is being evaluated as a novel chemotherapeutic agent that may complement other agents and treatment modalities for small-cell lung cancer (SCLC). Combination chemotherapy is the most effective means of improving the survival of patients with extensive disease, but until recently, no combination demonstrated superior efficacy. In a recent Japanese phase III study, irinotecan in combination with cisplatin significantly improved the survival of previously untreated patients with extensive SCLC compared to standard etoposide/cisplatin therapy (median progression-free survival: 6.9 vs 4.8 months, P = .003; median overall survival: 12.8 vs 9.4 months, P = .002). Two additional phase III trials have been planned in the United States to confirm these results, and to investigate how the administration schedule of irinotecan/cisplatin may be modified to improve its therapeutic index. The results of phase I/II studies have shown that other irinotecan-based combinations demonstrate promising activity in this disease as both first- and second-line therapy. This article reviews the rationale for the use of irinotecan in SCLC, examines key findings from recent clinical studies of irinotecan-based therapy, and discusses how the use of irinotecan in combination with new noncytotoxic anticancer agents can and will be further explored.
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PMID:Irinotecan therapy for small-cell lung cancer. 1201 33

Tirapazamine (TPZ), a hypoxia-selective cytotoxin, has demonstrated activity in cancer clinical trials. Under hypoxic conditions, TPZ is reduced to a radical that leads to DNA double-strand breaks (DSBs), single-strand breaks, and base damage. A previous finding of an association of the DSBs with protein led us to investigate the involvement of topoisomerase II (topo II) in their formation. Nuclear extracts from human lung cancer cells treated with either the topo II poison etoposide or TPZ under hypoxic conditions had markedly reduced topo II activity as judged by an inability to convert kinetoplast DNA from the catenated to the decatenated form. Because topo II poisons, such as etoposide, cause DNA DSBs, we hypothesized that pretreatment of cells with merbarone or aclarubicin, known catalytic inhibitors of topo II, would abrogate DNA DSBs caused by topo II. Cells pretreated with these catalytic inhibitors abrogated both DNA DSBs and cell kill induced by etoposide or by TPZ. Etoposide- and TPZ-mediated DSBs were also greatly reduced in a small cell lung cancer cell line with low levels of nuclear topo IIalpha. We also showed that topo IIalpha becomes covalently bound to DNA after TPZ treatment under hypoxic conditions, and that the cleavable complexes formed by TPZ are more stable over time than those formed by etoposide. Taken together, these data suggest that TPZ exerts its cytotoxic effect at least in part through poisoning topo II. Because TPZ is activated only under hypoxic conditions, which are characteristic of solid tumors, these data implicate TPZ as a tumor-specific topo II poison.
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PMID:Tirapazamine: a hypoxia-activated topoisomerase II poison. 1223 92

Although treatment of advanced non-small-cell lung cancer has been improved with the availability of such new agents as the taxanes, topoisomerase inhibitors, vinorelbine (Navelbine), and gemcitabine (Gemzar), platinum-based combination therapy has appeared to reach a threshold of therapeutic effectiveness. A paradigm shift in approach to non-small-cell lung cancer and other tumors may be heralded by the development of agents targeting specific biologic pathways in tumor development. Such new agents include antibody epithelial growth factor receptor (EGFR) inhibitors (eg, the monoclonal antibodies trastuzumab [Herceptin] and cetuximab [IMC-C225, Erbitux]) and EGFR tyrosine kinase inhibitors (eg, ZD1839 [Iressa] and OSI-774), angiogenesis inhibitors (eg, matrix metalloproteinase inhibitors), vascular endothelial growth factor (VEGF) inhibitors (eg, monoclonal antibody to VEGF ligand and small-molecule tyrosine kinase), and signal transduction inhibitors (eg, ISIS-3521, an antisense oligonucleotide to protein kinase C-alpha). A number of these agents have entered advanced-phase clinical investigation. It is likely that targeted therapy will have applications in combination with cytotoxic chemotherapy or radiation therapy at all stages of treatment, including maintenance therapy. It is even possible that these new biologic therapies will be used together as rational combinations (based on pathologic diagnosis) for advanced non-small-cell lung cancer.
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PMID:Targeted therapy in non-small-cell lung cancer. 1237 97

The DNA topoisomerase inhibitor irinotecan (CPT-11, Camptosar) is being evaluated as a novel chemotherapeutic agent for small-cell lung cancer that may complement other agents and treatment modalities. Combination chemotherapy is recognized as the most effective means of improving survival in patients with extensive-stage small-cell lung cancer, but until recently, no one combination had emerged as superior. In a recent Japanese phase III study, irinotecan in combination with cisplatin significantly improved survival of previously untreated patients with extensive small-cell lung cancer compared with standard etoposide/cisplatin therapy (median progression-free survival: 6.9 vs 4.8 months, P < .001; median overall survival: 12.8 vs 9.4 months, P = .0021). Two additional phase III trials are planned to confirm these results in the United States, and to investigate how the irinotecan/cisplatin administration schedule may be modified to improve therapeutic index. This article will review the use of irinotecan in combination with cisplatin in patients with small-cell lung cancer.
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PMID:Irinotecan plus cisplatin in small-cell lung cancer. 1237

Despite its low efficacy, radiotherapy has traditionally been considered the mainstay of treatment in inoperable stage III NSCLC. One of the attempts to improve the outcome is combining radiation with chemotherapy. This strategy is expected to increase the cure rate not only by improved locoregional tumor control but also by elimination of micrometastases outside the radiotherapy field. Chemotherapy and radiation may be applied in sequence or concurrently. The results of randomized studies testing these two strategies have been inconsistent, however a series of recent trials and the metaanalysis demonstrated a survival benefit of chemoradiation over radiotherapy alone. Recently, concurrent chemotherapy and radiation was found to be superior to sequential application but toxicity of the former is higher. The value of new agents (taxanes, vinorelbine, gemcitabine and topoisomerase inhibitors) in combined modality therapy of NSCLC seems to be promising, but warrants further clinical evaluation.
Lung Cancer 2002 Dec
PMID:Combined chemotherapy and radiotherapy in inoperable non-small cell lung cancer. 1246 44

Two human small cell lung cancer (SCLC) subpopulations, CPH 54A, and CPH 54B, established from the same patient tumor by in vitro cloning, were investigated. The tumor was classified as intermediate-type SCLC. The cellular sensitivity to ionizing radiation (IR) was previously determined in the two sublines both in vivo and in vitro. Here we measured the etoposide (VP16) sensitivity together with the induction and repair of VP16- and IR-induced DNA double-strand breaks (DSBs). The two subpopulations were found to differ significantly in sensitivity to VP16, with the radioresistant 54B subline also being VP16 resistant. In order to explain the VP16 resistant phenotype several mechanisms where considered. The p53 status, P-glycoprotein, MRP, topoisomerase IIalpha, and Mre11 protein levels, as well as growth kinetics, provided no explanations of the observed VP16 resistance. In contrast, a significant difference in repair of both VP16- and IR-induced DSBs, together with a difference in the levels of the DSB repair proteins DNA-dependent protein kinase (DNA-PK(cs)) and RAD51 was observed. The VP16- and radioresistant 54B subline exhibited a pronounced higher repair rate of DSBs and higher protein levels of both DNA-PK(cs) and RAD51 compared with the sensitive 54A subline. We suggest, that different DSB repair rates among tumor cell subpopulations of individual SCLC tumors may be a major determinant for the variation in clinical treatment effect observed in human SCLC tumors of identical histological subtype.
Lung Cancer 2003 May
PMID:DNA repair rate and etoposide (VP16) resistance of tumor cell subpopulations derived from a single human small cell lung cancer. 1271 Nov 16

The p21(WAF1/Cip1) gene plays a central role in cell cycle regulation. Here we show that topoisomerase II inhibitors, genistein and etoposide, induce p21(WAF1/Cip1) expression mainly in a p53-dependent manner in human lung cancer cell line A549. However, although p53 accumulated, p21(WAF1/Cip1) expression did not depend on the level of Ser15 phosphorylation of p53. Caffeine, an ataxia telangiectasia-mutated (ATM), and ATM- and Rad3-related kinase (ATR) inhibitor, abrogated genistein-induced p21(WAF1/Cip1) and largely blocked etoposide-induced p21(WAF1/Cip1) expression. Wortmannin, an ATM- and DNA-dependent protein kinase inhibitor, partially inhibited p21(WAF1/Cip1) expression induced by genistein and etoposide, whereas UCN-01, a Chk1 inhibitor, partially blocked etoposide, but not genistein-induced p21(WAF1/Cip1) expression. These data suggest that both genistein and etoposide induce p21(WAF1/Cip1) expression in a p53-dependent manner. Genistein appears to stimulate p21(WAF1/Cip1) expression through p53 via ATM, whereas etoposide may activate both ATM and ATR pathways. Our results suggest different mechanisms participate in genistein and etoposide induced p21(WAF1/Cip1) expression.
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PMID:P21 response to DNA damage induced by genistein and etoposide in human lung cancer cells. 1276 22


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