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Query: UMLS:C0242379 (lung cancer)
 71,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Small cell lung cancer (SCLC) is an aggressive type of lung cancer, for which cytotoxic chemotherapy appears to have reached its maximal efficacy. This neoplasm is characterized by the overexpression of several receptor tyrosine kinases (RTKs), especially c-Kit. The ligand for c-Kit is stem cell factor (SCF). In SCLC, SCF can influence c-Kit activation by autocrine or paracrine mechanisms. We have recently shown that the c-Kit/SCF pathway is operational in SCLC and can be inhibited by Glivec (STI571). Because the inhibition of topoisomerase-I (topo-I) is one approach used to treat SCLC, we determined the effects of c-Kit/SCF signaling on topo-I activity. A unique phosphorylation of c-Kit on amino acid 823 and amino acid 703 was identified with the SCF stimulation of H526 cells. We demonstrate that with SCF stimulation over 16 hours (dose response 0-100 ng/mL) in H526 SCLC cells (c-Kit positive, SCF responsive), a decrease in topo-I activity was observed, whereas in H82 SCLC cells (c-Kit negative, SCF unresponsive) there was no modulation of topo-I activity by SCF. Using STI571 (5 microM, 16 hours) to inhibit the c-Kit pathway following stimulation with SCF (100 ng/mL), an upregulation of topo-I activity was observed in H526 cells but not in H82 cells. Performing viability assays, we show that STI571 in combination with topo-I inhibition by camptothecin or SN38, the active metabolite of irinotecan, can cooperatively inhibit H526 cell viability (but not H82 cell viability) for 72 hours. We also show that STI571 does not directly inhibit topo-I activity in SCLC. The combination of STI571 with topo-I inhibition could provide a useful combination in the treatment of SCLC.
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PMID:Modulation of c-Kit/SCF pathway leads to alterations in topoisomerase-I activity in small cell lung cancer. 1551 Dec 12

This article consists of an analysis of the available scientific research on botanically derived compounds that have potential efficacy in the treatment of lung cancer. The mechanisms of activity reviewed include alkylating agents, topoisomerase poisons, DNA synthesis inhibitors, protein synthesis inhibitors, immunoceuticals, and lipoxygenase inhibitors. Selection criteria include: (1) products whose activity have at least minimal scientific confirmation - preclinical (in vitro, in vivo) or clinical; (2) products with a well-defined chemical composition; or (3) products with a well-known or scientifically plausible mechanism of activity.
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PMID:Pharmacologically active natural compounds for lung cancer. 1565 12

Hypoxia has clinically been associated with resistance to chemotherapy. The aim of this study was to investigate whether hypoxia induces resistance to doxorubicin and mitoxantrone, two common drugs in cancer treatment, in MCF-7 breast cancer cells, and SW1573 non-small lung cancer cells. In addition, the role of drug transporters P-gp, BCRP and MRP1 was analysed. Hypoxia induced resistance in MCF-7 cells to mitoxantrone shifted the IC(50) value from 0.09 microM (+/-0.01) to 0.54 microM (+/-0.06) under hypoxia, whereas survival of MCF-7 and SW1573 cells in the presence of doxorubicin was not altered. Accumulation of mitoxantrone and daunorubicin, a doxorubicin fluorescent homologue, appeared to be 5.3 and 3.2 times lower in MCF-7 cells, respectively. Cytotoxicity assays showed no increased functionality of the drug transporters P-gp, BCRP and MRP1 under hypoxia. In addition, protein levels of these drug transporters were not changed. Medium of the MCF-7 cells became more acidic under hypoxia thereby causing a decreased uptake of mitoxantrone. Hypoxia induces mitoxantrone resistance in MCF-7 cells not mediated by the three major MDR transporters. Hypoxia-induced acidification may cause this resistance by decreased cellular uptake together with a lowered cytotoxicity due to pH-dependent topoisomerase type II activity.
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PMID:Hypoxia-induced acidification causes mitoxantrone resistance not mediated by drug transporters in human breast cancer cells. 1575 Feb 6

Irinotecan is a topoisomerase I inhibitor that is highly active against small cell lung cancer (SCLC). Etoposide is another drug that is effective for SCLC. Since combination of these two topoisomerase inhibitors revealed a synergistic effect in vitro and showed a safety in phase I study, we conducted a phase II study in patients with previously un-treated extensive disease (ED) SCLC to evaluate the efficacy and toxicity of this combination. Fifty patients with previously untreated ED-SCLC were enrolled. Irinotecan was administered intravenously at 60mg/m(2) on days 1, 8, and 15, while etoposide was given at 80mg/m(2) on days 2-4. Treatment was repeated every 4 weeks for four cycles. The overall response rate was 66.0%, with a complete response rate of 10.0%. The median survival time was 11.5 months and the 1- and 2-year survival rates were 43.2 and 14.4%, respectively. The major toxicity of this regimen was myelosuppression, including grade 3 or 4 neutropenia (62.9%), leukopenia (28.0%), and anemia (14%). The other grade 3 toxicity was diarrhea (2%). This irinotecan and etoposide regimen is active against ED-SCLC with relatively mild toxicity.
Lung Cancer 2005 Aug
PMID:Irinotecan and etoposide for previously untreated extensive-disease small cell lung cancer: a phase II trial of West Japan Thoracic Oncology Group. 1602 21

Hybrid biosynthetic approach produced a new anthracycline ID6105 (11-hydroxyaclacinomycin X, Hyrubicin), which has potent antitumor activities against a broad range of cancer cell lines. Like other anthracyclines, ID6105 has the inhibitory effects on DNA synthesis as well as topoisomerase II. As preclinical studies of ID6105, we investigated ID6105's efficacy on human tumors, and cardiotoxicity. In human tumor xenografts, the ID6105's antitumor effects were greater than other anticancer drugs. ID6105 induced tumor regression in Hep G2 human hepatoma model, and slowed down the tumor growth rates in several tumor models. Doxorubicin-refractory tumors such as PC-3, DU-145, and CX-1 were sensitive to ID6105, and the growth of EKVX, lung cancer, which did not respond to paclitaxel, was also inhibited by ID6105, but tumor mass in CFPA, MCF7, and HCT-15 was not reduced by ID6105. The cardiotoxicity of ID6105 has also been assessed in rats. ID6105 did not induce any remarkable histopathological changes in hearts, and its lipid peroxidation in rat cardiac muscles did not occur as much as doxorubicin, indicating that the cardiotoxicity of ID6105 is remarkably lower than that of doxorubicin. Taking all into account, our results suggest that ID6105 would be a promising candidate for a novel anthracycline chemotherapeutic agent.
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PMID:In vivo antitumor efficacy and cardiotoxicity of novel anthracycline ID6105 (11-hydroxy-aclacinomycin X, Hyrubicin). 1617 93

The ganglioside patterns have been shown to dramatically change during cell proliferation and differentiation and in certain cell-cycle phases, brain development, and cancer malignancy. To investigate the significance of the ganglioside GM3 in cancer malignancy, we established GM3-reconstituted cells by transfecting the cDNA of GM3 synthase into a GM3-deficient subclone of the 3LL Lewis lung carcinoma cell line (Uemura, S. (2003) Glycobiology, 13, 207-216). The GM3-reconstituted cells were resistant to apoptosis induced by etoposide and doxorubicin. There were no changes in the expression levels of topoisomerase IIalpha or P-glycoprotein, or in the uptake of doxorubicin between the GM3-reconstituted cells and the mock-transfected cells. To understand the mechanism of the etoposide-resistant phenotype acquired in the GM3-reconstituted cells, we investigated their apoptotic signaling. Although no difference was observed in the phosphorylation of p53 at serine-15-residue site by etoposide between the GM3-reconstituted cells and mock-transfected cells, the activation of both caspase-3 and caspase-9 was specifically inhibited in the former. We found that the anti-apoptotic protein B-cell leukemia/lymphoma 2 (Bcl-2) was increased in the GM3-reconstituted cells. Moreover, wild-type 3LL Lewis lung carcinoma cells, which have an abundance of GM3, exhibited no DNA fragmentation following etoposide treatment and expressed higher levels of the Bcl-2 protein compared with the J5 subclone. Thus, these results support the conclusion that endogenously produced GM3 is involved in malignant phenotypes, including anticancer drug resistance through up-regulating the Bcl-2 protein in this lung cancer cell line.
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PMID:Endogenously produced ganglioside GM3 endows etoposide and doxorubicin resistance by up-regulating Bcl-2 expression in 3LL Lewis lung carcinoma cells. 1657 67

EGFR mutations are a major determinant of lung tumor response to gefitinib, an EGFR-specific tyrosine kinase inhibitor. Obtaining a response from lung tumors expressing wild-type EGFR is a major obstacle. The combination of gefitinib and cytotoxic drugs is one strategy against lung cancers expressing wild-type EGFR. The DNA topoisomerase inhibitor irinotecan sulfate (CPT-11) is active against lung cancer. We examined the sensitivity of lung cancers expressing wild- or mutant-type EGFR to the combination of gefitinib and CPT-11. The in vitro effect of gefitinib and SN-38 (the active metabolite of CPT-11) was examined in seven lung cancer cell lines using the dye formation assay with a combination index. When administered concurrently, gefitinib and SN-38 had a synergistic effect in five of the seven cell lines expressing wild-type EGFR, whereas the combination was antagonistic in PC-9 cells and a PC-9 subline resistant to gefitinib and expressing deletional mutant EGFR (PC-9/ZD). When administered sequentially, treatment with SN-38 followed by gefitinib had remarkable synergistic effects in the PC-9 and PC-9/ZD cells. In an in vivo tumor-bearing model, this combination had a schedule-dependent synergistic effect in the PC-9 and PC-9/ZD cells. An immunohistochemical analysis of the tumors in mice treated with CPT-11 and gefitinib demonstrated that the number of Ki-67 positive tumor cells induced by CPT-11 treatment was decreased when CPT-11 was administered in combination with gefitinib. In conclusion, the sequential combination of CPT-11 and gefitinib is considered to be active against lung cancer.
Lung Cancer 2006 Jul
PMID:Effects of different combinations of gefitinib and irinotecan in lung cancer cell lines expressing wild or deletional EGFR. 1671 12

The substituted chloroisoquinolinediones and pyrido[3,4-b]phenazinediones were synthesized, and the cytotoxic activity and topoisomerase II inhibitory activity of the prepared compounds were evaluated. Chloroisoquinolinediones have been prepared by the reported method employing 6,7-dichloroisoquinoline-5,8-dione. The cyclization to pyrido[3,4-b]phenazinediones was achieved by adding the aqueous sodium azide solution to the dimethylformamide solution of corresponding chloroisoquinoline-5,8-dione. The cytotoxicity of the synthesized compounds was evaluated by a SRB (Sulforhodamine B) assay against various cancer cell lines such as A549 (human lung cancer cell line), SNU-638 (human stomach cancer cell), Col2 (human colon cancer cell line), HT1080 (human fibrosarcoma cell line), and HL-60 (human leukemia cell line). Almost all the synthesized pyrido[3,4-b]phenazinediones showed greater cytotoxic potential than ellipticine (IC(50)=1.82-5.97 microM). In general, the cytotoxicity of the pyrido[3,4-b]phenazinediones was higher than that of the corresponding chloroisoquinolinediones. The caco-2 cell permeability of selected compounds was 0.62 x 10(-6)-35.3 x 10(-6)cm/s. The difference in cytotoxic activity among tested compounds was correlated with the difference in permeability to some degree. To further investigate the cytotoxic mechanism, the topoisomerase II inhibitory activity of the synthesized compounds was estimated by a plasmid cleavage assay. Most of compounds showed the topoisomerase II inhibitory activity (28-100%) at 200 microM. IC(50) values for the most active compound 6a were 0.082 microM. However, the compounds were inactive for DNA relaxation by topoisomerase I at 200 microM.
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PMID:Synthesis of 6-chloroisoquinoline-5,8-diones and pyrido[3,4-b]phenazine-5,12-diones and evaluation of their cytotoxicity and DNA topoisomerase II inhibitory activity. 1703 25

The inhibition of topoisomerase I by topotecan results in a compensatory increase in topoisomerase II associated with increased in vitro sensitivity of tumors to etoposide. Maximal synergy has been observed for the sequence of topotecan followed by etoposide. Carboplatin has clinical activity when combined with either of these two agents. These interactions were the pharmacologic rationale for topotecan p.o. days 1-5, carboplatin i.v. day 6, and etoposide p.o. days 6-10. Three successive dose levels were explored: (1) topotecan 2mg/day, carboplatin AUC 5, etoposide 150 mg/day; (2) topotecan 3mg/day, carboplatin AUC 5, etoposide 150 mg/day; and (3) topotecan 3mg/day, carboplatin AUC 5, etoposide 200mg/day. Filgrastim 5 microg/kg/day was injected s.c. days 11-18. Up to 6 cycles were administered every 21 days. Eligible patients had measurable or evaluable, extensive disease, small lung cell lung cancer, no prior chemotherapy, ECOG performance status 0-2, and adequate hematologic, renal, and hepatic function. Follow-up was weekly for CBC. Tumor response was assessed after 2 and 6 cycles. Dose limiting toxicity (DLT) was defined as any of the following in cycle 1: grade 3 or 4 non-hematologic toxicity other than nausea and vomiting, grade 4 neutropenia lasting more than 3 days, neutropenic fever or sepsis, grade 4 thrombocytopenia, or failure to recover neutrophils >or=1500/microl or platelets >or=100,000/microl by day 28. Ten patients were enrolled: median age 62 (range, 50-79); female/male 4/6; and performance status 0/1/2 in 2/7/1. Three patients each were treated on dose levels 1 and 2 without DLT. The first 2 patients entered on dose level 3 had no DLT. The third patient on dose level 3 developed grade 4 neutropenia lasting more than 3 days, neutropenic fever, and grade 4 thrombocytopenia on day 15 of cycle 1. The fourth patient on dose level 3 developed grade 4 thrombocytopenia on day 18 of cycle 1. One patient received only 1 cycle and was not evaluable for response. Seven patients completed 6 cycles: 1 had a complete response and 6 achieved a partial response. The third patient on dose level 3 received 2 cycles and had stable disease, but had to be removed from protocol treatment because of grade 4 neutropenia despite dose reduction in cycle 2. The fourth patient on dose level 3 achieved a partial response, but had to be removed from protocol therapy after cycle 5 because of recurrent grade 4 thrombocytopenia. In conclusion, neutropenia and thrombocytopenia were dose-limiting. The maximum tolerated dose (MTD) is topotecan 3mg/day p.o. days 1-5, carboplatin AUC 5i.v. day 6, and etoposide 150 mg/day p.o. days 6-10 with filgrastim.
Lung Cancer 2006 Dec
PMID:Phase I and pharmacologic study of sequential topotecan-carboplatin-etoposide in patients with extensive stage small cell lung cancer. 1704 3

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


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