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

To study the problem of acquired resistance to widely used anti-cancer drugs that target the 170 kDa topoisomerase IIalpha (topo IIalpha), a drug-resistant human small-cell lung cancer cell line, H209/VP, was selected in VP-16. H209/VP cells express reduced levels of the 170 kDa topo IIalpha that is localized normally in the nucleus and also express lower levels of a 160 kDa topo IIalpha-related protein that is located predominantly in the cytoplasm. Band depletion immunoblotting experiments suggest that the H209/VP nuclear 170 kDa topo IIalpha is able to form ternary complexes with DNA and VP-16 in intact cells, but the ability of the cytoplasmic 160 kDa protein to do so is greatly diminished. Sequence analysis of the 3; end of the H209/VP mutant topo IIalpha mRNA and the TOP2A gene indicates that the mRNA is missing 200 nt that corresponds to exon 34 because the partial loss of the minimal 3; splice-acceptor sequence at the beginning of exon 34 results in splicing of exon 33 to exon 35. The protein predicted to be encoded by this mutant mRNA does not contain the COOH-terminal 109 amino acids of the wild-type enzyme that we have demonstrated contain a strongly functional nuclear localization signal sequence. Consequently, our data explain both the size and the cytoplasmic localization of the H209/VP mutant topo IIalpha. The mutant TOP2A allele in H209/VP cells differs from those in previously characterized cell lines with cytoplasmic topo IIalpha and extends the number of types of resistance-associated deletions in this region to 4. These findings indicate that this region of the TOP2A gene may be a hot spot for mutations.
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PMID:A truncated cytoplasmic topoisomerase IIalpha in a drug-resistant lung cancer cell line is encoded by a TOP2A allele with a partial deletion of exon 34. 1069 27

Certain drugs used in the treatment of lung cancer and other human malignancies are cytotoxic because of their ability to interact with the two isoforms of topoisomerase II (topo II), topo IIalpha and topo IIbeta. As part of an effort to evaluate the contribution of topo II alterations to drug sensitivity and resistance in lung cancer, we have developed a semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay to measure levels of topo II alpha and beta mRNAs simultaneously using a single pair of primers with sequences common to both isoforms. The PCR products derived from the topo II alpha and beta mRNAs are both 446 bp but have different electrophoretic mobilities in a nondenaturing polyacrylamide gel, allowing sensitive, rapid quantitation when the products are radiolabeled with [35S]-dATP. Using this RT-PCR method, poly(A+) RNA from 13 non-small cell lung cancer (NSCLC) cell lines was analyzed. The results obtained indicated that the cell lines express a wide range of topo II alpha mRNA levels (12-fold) and topo IIbeta mRNA levels (5.5-fold). Tumor and normal lung tissues from 25 patients with NSCLC were also examined. In the tumor samples, the levels of the topo II alpha and beta mRNAs were similar. However, mean topo IIalpha mRNA levels in the tumors were approximately 7-fold higher than those of the paired normal lung tissues. In contrast, topo IIbeta mRNA levels were similar in both tumor and normal lung. Topo II alpha and beta mRNA levels were both significantly lower in the squamous cell tumors than in the adenocarcinoma samples. Topo IIbeta mRNA levels in the squamous cell tumors were also significantly lower than those in paired normal lung tissue. The RT-PCR method described is reliable and convenient, and for the first time, makes the rapid simultaneous direct comparison of topo IIalpha and topo IIbeta mRNA levels feasible in large numbers of clinical samples.
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PMID:Simultaneous quantitation of topoisomerase II alpha and beta isoform mRNAs in lung tumor cells and normal and malignant lung tissue. 1087 30

Over the last decade, a group of new agents with differing mechanisms of action have shown great promise in early clinical studies in non-small-cell lung cancer (NSCLC). These include the taxanes docetaxel (Taxotere) and paclitaxel (Taxol); the nucleoside analog gemcitabine (Gemzar); the vinca alkaloid vinorelbine (Navelbine); the topoisomerase-I inhibitor irinotecan (Camptosar, CPT-11); and the bioreductive agent tirapazamine. Cisplatin (Platinol), which has been the "backbone" of combination chemotherapy in patients with NSCLC because of its proven single-agent activity, has been examined in combination with these agents as well as radiation and surgery in numerous trials. This article summarizes trials of these combination therapies in the treatment of NSCLC.
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PMID:Chemotherapy in metastatic non-small-cell lung cancer. 1098 Dec 87

Cancer management in the older patient is a growing concern, particularly with the increasing geriatric population and the high incidence of cancer among these individuals. Incidence of lung cancer in particular is known to rise with age. This article reviews prognosis, treatment options, and decision-making issues for both clinician and patient with respect to both non-small-cell and small-cell lung cancer in this population. Research findings dealing with response rates, survival rates, and symptom control in this age group are reviewed for radiotherapy, surgery, and for various chemotherapy agents, including gemcitabine, the taxanes, vinorelbine, and the topoisomerase 1 inhibitors. Quality- of-life issues are also addressed.
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PMID:Management of elderly patients with lung cancer. 1112 29

The management of non-small-cell lung cancer is undergoing rapid evolution. Although the advent of combined-modality therapy has led to improved survival, most patients eventually succumb to the disease. The arrival of a new generation of chemotherapeutic agents--including the taxanes, gemcitabine (Gemzar), and topoisomerase inhibitors such as irinotecan (Camptosar, CPT-11)--offers the hope of advances against this malignancy. Irinotecan, a camptothecin derivative, has shown impressive activity in a variety of solid tumors, including non-small-cell lung cancer. It is believed to act by stabilizing the topoisomerase-DNA complex formed during diverse cellular processes, including replication and transcription. A considerable body of evidence also demonstrates that camptothecin and its derivatives possess substantial radiosensitization properties. This article will review the in vitro and in vivo data on irinotecan's ability to render tumors more susceptible to ionizing radiation. It will then focus on experience with irinotecan and thoracic radiation in the treatment of non-small-cell lung cancer, which has yielded acceptable toxicity results and response rates in excess of 60% in early trials. It is hoped that newer treatment strategies--such as the combination of radiation and irinotecan in lung cancer--will significantly impact cure rates in the future.
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PMID:Irinotecan in combined-modality therapy for locally advanced non-small-cell lung cancer. 1122 Oct 19

Resistance to chemotherapy is common in non-small cell lung cancer. The aim of this study was to investigate the prognostic impact of in vitro established drug resistance markers on the response to chemotherapy in patients with advanced non-small cell lung cancer. Samples of 38 patients were analyzed by immunohistochemical staining, for topoisomerase IIalpha and IIbeta, Ki-67, MRP and LRP. In addition, mutation analysis of the topoisomerase IIalpha gene, the B/DNBS and the Tyr804 region, was performed. Lung tumor biopsies were taken prior for treatment with one of the following regimens; cisplatin/paclitaxel, cisplatin/VM26 or VP16, or carboplatin/VP16/ifosfamide. Seventeen patients obtained a partial response, 12 had stable disease and nine patients had progressive disease. None of the investigated markers was related with overall response rate. In one sample a point mutation in the B/DNBS region of the topo IIalpha gene was detected which substitutes IIe(510) with Val. This tumor had a partial response to four courses of cisplatin/VP16 treatment. The survival analysis showed that the patients with high topo IIalpha expressing tumors had a significantly worse survival compared with the patients with low or intermediate topo IIalpha expressing tumors. In conclusion, no relation was observed between expression of topoisomerase IIalpha, IIbeta, Ki-67, MRP or LRP and response rate. Furthermore, worse survival was seen in patients with high topoisomerase IIalpha expressing tumors. In one tumor sample, a newly described mutation in the B/DNBS region of the topo IIalpha gene was detected, which does not appear to be related to drug resistance.
Lung Cancer 2001 May
PMID:Topoisomerase IIalpha and other drug resistance markers in advanced non-small cell lung cancer. 1132 82

The candidate tumour suppressor gene, LUCA-15, maps to the lung cancer tumour suppressor locus 3p21.3. Overexpression of an alternative RNA splice variant of LUCA-15 has been shown to retard human Jurkat T cell proliferation and to accelerate CD95-mediated apoptosis. An antisense cDNA to the 3'-UTR of this splice variant was able to suppress CD95-mediated apoptosis. Here, we report that overexpression of LUCA-15 itself suppresses CD95-mediated apoptosis in Jurkat cells. This suppression occurs prior to the final execution stage of the CD95 signalling pathway, and is associated with up-regulation of the apoptosis inhibitory protein Bcl-2. LUCA-15 overexpression is also able to inhibit apoptosis induced by the protein kinase inhibitor staurosporine, but is not able to significantly suppress apoptosis mediated by the topoisomerase II inhibitor etoposide. These findings suggest that LUCA-15 is a selective inhibitor of cell death, and confirm the importance of the LUCA-15 genetic locus in the control of apoptosis.
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PMID:LUCA-15 suppresses CD95-mediated apoptosis in Jurkat T cells. 1142 Jun 83

Inhibition of topoisomerase I by topotecan results in a compensatory increase in topoisomerase II levels associated with increased in vitro sensitivity of tumors to etoposide. Maximum synergy has been observed for the sequence of topotecan followed by etoposide. This is the pharmacologic rationale for the sequence of topotecan 0.4 mg/m(2) per day for 7 days continuous i.v. infusion, carboplatin i.v. on day 8, and etoposide 50 mg per day p.o. days 9 through 20. The carboplatin dosage was escalated from an AUC of 4 to 5 to 6 (Calvert formula). Up to six treatment cycles were administered at 28-day intervals. Eligible patients had metastatic non-small cell lung cancer (NSCLC) or extensive disease small lung cell lung cancer (SCLC), no prior chemotherapy, performance status 0-2, and adequate organ function. Follow-up was twice weekly in the first cycle for CBC and for topotecan and etoposide concentrations. Follow-up, thereafter, was weekly. Tumor response was assessed after two and six cycles and then as clinically indicated. At carboplatin AUCs of 4 and 5, no NCI grade 4 toxicity was observed in cycle 1 in cohorts of three patients each. At the AUC of 5, two patients experienced dose-limiting events after cycle 3, one grade 4 neutropenia lasting >3 days (no fever) and one failure to recover an absolute neutrophil count >1500/microl by day 35. This was, therefore, deemed the maximal tolerable dose. Number of treatment cycles per patient ranged between 1 and 6, and three patients completed six cycles. All patients were male, age 47-71, with NSCLC in one and SCLC in six. The patient with NSCLC had progressive disease after one cycle. One complete and three partial responses were observed in five patients with SCLC. Mean steady-state plasma concentrations during topotecan infusion ranged from 0.73 to 1.69 ng/ml, and mean etoposide concentrations ranged from 60 to 230 ng/ml. This sequence of topotecan, carboplatin, and etoposide appeared tolerable and active. Neutropenia was the dose-limiting toxicity.
Lung Cancer
PMID:Phase I and pharmacologic study of sequential topotecan, carboplatin, and etoposide. 1155 19

Topoisomerase targeting chemotherapy is an excellent strategy for lung cancer treatment. We studied the cytotoxic effects of exposure to topoisomerase I inhibitor SN-38 and topoisomerase II inhibitor etoposide (VP-16) in lung cancer cell line Ma-1 using WST-1 assay and isobologram analysis. Cells were concurrently or sequentially exposed to drugs for 30 minutes, 2 hours and 24 hours. Simultaneous exposure for 30 minutes showed antagonistic. However, 2 hours or 24 hours exposure resulted in additive or supra-additive interaction, respectively. Sequential exposures to SN-38 followed by VP-16 resulted in synergistic interaction for all schedules. Whereas, VP-16 followed by SN-38 resulted in sub-additive interaction for 30 minutes and 2 hours exposures, however, 24 hours exposure resulted in additive interaction. These findings suggest that maximum cytotoxic effects can be obtained when SN-38 precedes VP-16, and that prolonged simultaneous administration may circumvent antagonistic interaction between them. These findings may be useful in clinical trials.
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PMID:In vitro schedule dependency in the treatment of topoisomerase I and II inhibitor. 1155 90

Y box-binding protein-1 (YB-1), a member of the DNA binding protein family, interacts with inverted CCAAT boxes (Y-boxes). Y-boxes are located on the promoter of numerous genes, such as DNA topoisomerase IIalpha (Topo IIalpha), proliferating cell nuclear antigen (PCNA) and multidrug resistance 1 (MDR1). In this study, we used immunohistochemical (IHC) staining to detect YB-1 expression in 59 lung cancer tissues and to evaluate whether YB-1 expression was associated with the expression of YB-1 target genes such as Topo IIalpha, PCNA and MDR1 in human lung carcinoma. Twenty-eight out of 59 cases (47.5%) were stained positive for YB-1 in the cytoplasm, while 30 out of 59 cases (50.8%) were positive for PCNA in the nuclei. Topo IIalpha-positive cells were detected in 16 out of 59 cases (27.1%). Eight out of 59 cases (13.6%) had greater than 5% P-gp positive cells expression. There was a significant correlation between the YB-1 and Topo IIalpha expression in small cell lung cancer (SCLC) (p=0.0242). YB-1 expression also correlated with PCNA expression in non-small cell lung cancer (NSCLC) (p=0.0001). Higher levels of YB-1 expression were associated with T3-4 and Stage III-IV tumors in adenocarcinomas (p=0.0072; p=0.0168). In contrast, no relationship was found between YB-1 expression and P-gp expression. Our study suggests that YB-1 expression correlates with Topo IIalpha and PCNA expression in lung cancer.
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PMID:Expression of Y box-binding protein-1 correlates with DNA topoisomerase IIalpha and proliferating cell nuclear antigen expression in lung cancer. 1172 93


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