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Biomedical subjects

M R Green

Publications and source records attributed to M R Green.

At least 19 recordsLinked to original sources
PubMed2006

Phase II trial of irinotecan/gemcitabine as second-line therapy for relapsed and refractory small-cell lung cancer: Cancer and Leukemia Group B Study 39902.

BACKGROUND: This phase II study evaluated the efficacy and safety of the irinotecan/gemcitabine combination in patients with relapsed/refractory small-cell lung cancer (SCLC). PATIENTS AND METHODS: Patients with measurable tumor who had received one previous chemotherapy or chemotherapy/radiation regimen were eligible. Gemcitabine 1000 mg/m(2) was administered i.v. over 30 min followed immediately by irinotecan 100 mg/m(2) i.v. over 90 min, both on days 1 and 8 every 21 days. Patients were stratified based on response to initial treatment [i.e. primary sensitive disease with progression >or=3 months (group A), or refractory disease (group B)]. RESULTS: Seventy-three patients were enrolled but one never received treatment and one ineligible patient did not have SCLC. Median patient ages of the remaining patients were 61 and 63 years in groups A (n = 35) and B (n = 36), respectively, with performance status of 0 or 1 in 85% of 71 patients. Primary grade 3/4 toxic effects in groups A versus B were neutropenia (36% versus 43%), thrombocytopenia (36% versus 26%), nausea (12% versus 11%), vomiting (0 versus 11%), diarrhea (12% versus 9%), and pulmonary (12% versus 12%). Two patients had fatal events including pneumonitis (n = 1) and acute respiratory distress syndrome (n = 1). Responses occurred in 11 group A [two complete responses and nine partial responses (PRs)] and four group B (all PRs) patients, for response rates of 31% [95% confidence interval (CI) 17%, 49%) and 11% (95% CI 3%, 26%), respectively. Median survival and progression-free survival times were 7.1 (95% CI 6, 10.5) versus 3.5 (95% CI 3.1, 5.7) months, and 3.1 (95% CI 1.6, 5.3) versus 1.6 (95% CI 1.4, 2.8) months for group A versus B. CONCLUSION: The irinotecan/gemcitabine combination is active and well tolerated as second-line therapy in SCLC patients. Additional studies are warranted as second-line therapy in patients who progressed 90 days or more after first-line therapy. However, the observed efficacy results in refractory SCLC patients indicate that this regimen should not be further explored in this population.

Adult↗
PubMed2006

Abraxane, a novel Cremophor-free, albumin-bound particle form of paclitaxel for the treatment of advanced non-small-cell lung cancer.

BACKGROUND: Abraxane (ABI-007) is a novel 130-nm, albumin-bound (nab) particle form of paclitaxel designed to utilize endogenous albumin pathways to increase intratumor concentrations of the active drug. This multicenter phase II study was designed to evaluate the efficacy and safety of Abraxane 260 mg/m2 every 3 weeks in patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: Patients with histologically confirmed, measurable NSCLC received Abraxane as first-line therapy. RESULTS: Forty-three patients were enrolled. The overall response rate was 16%; the disease control rate was 49%. Median time to progression was 6 months, and median survival was 11 months. The probability of not having progressed by 1 year was 13%; the probability of surviving 1 year was 45%. No severe hypersensitivity reactions were reported despite the lack of premedication; 95% of patients were treated without dose reduction. Two patients (5%) discontinued therapy because of treatment-related toxicities (neuropathy, fatigue [1 each]). No grade 4 treatment-related toxicity occurred. CONCLUSIONS: Abraxane 260 mg/m2 administered IV over 30 min without premedication was well tolerated. Significant tumor responses and prolonged disease control were documented in this group of patients with NSCLC. Exploration of higher doses of ABI-007 alone and in combination with other drugs active in NSCLC is warranted.

Adult↗
PubMed2006

Defective maturation of dendritic cells in common variable immunodeficiency.

Monocyte-derived dendritic cells (MdDCs) from many patients with common variable immunodeficiency (CVID) have been shown recently to have reduced expression of surface molecules associated with maturity. Using flow cytometry and confocal microscopy, we now show that this is due to a partial failure to fix Class II DR molecules on the surface during procedures that induce full maturation in vitro in cells from normal subjects. Major histocompatibility complex (MHC) class I, CD86 and CD83 expression were expressed normally, but CD40 was reduced. These abnormalities are unlikely to be due to prior in vivo exposure of monocytes to lipopolysaccharide (LPS), as addition of LPS to monocytes from normal subjects in vitro caused a different pattern of changes. CVID MdDCs retained Class II DR in the cytoplasm during maturation, showed increased internalization of cross-linked Class II DR surface molecules and were unable to polarize DR within a lipid raft at contact sites with autologous lymphocytes. These cells retained some features of monocytes, such as the ability to phagocytose large numbers of fixed yeast and fluorescent carboxylated microspheres and expression of surface CD14. These abnormalities, if reflected in vivo, could compromise antigen presentation and may be a fundamental defect in the mechanism of the antibody deficiency in a substantial subset of CVID patients.

Adult↗
PubMed2004

Randomized phase II trial of gemcitabine plus irinotecan or docetaxel in stage IIIB or stage IV NSCLC.

BACKGROUND: To evaluate the activity and tolerability of gemcitabine plus irinotecan or docetaxel as first-line chemotherapy for advanced non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: Eligible patients with chemotherapy-naïve stage IIIB or IV NSCLC were randomized to receive gemcitabine 1000 mg/m2 on days 1 and 8, plus either irinotecan 100 mg/m2 or docetaxel 40 mg/m2 on days 1 and 8. Treatment was administered every 3 weeks. RESULTS: Of the 80 enrolled patients with stage IIIB or IV NSCLC, 78 were evaluable for activity and safety. Overall response rates, consisting of partial responses, were 12.8% [95% confidence interval (CI) 4% to 35%] for gemcitabine-irinotecan and 23.1% (95% CI 10% to 42%) for gemcitabine-docetaxel. Median overall survival was 7.95 months (95% CI 5.2-10.2) and 12.8 months (95% CI 7.9-17.1) for gemcitabine-irinotecan and gemcitabine-docetaxel, respectively. The corresponding estimated 1-year survivals were 23% and 51%, respectively. The 2-year survival rate in arm A (gemcitabine-irinotecan) is not currently estimable. The 2-year survival rate for arm B (gemcitabine-docetaxel) is 22% (95% CI 6% to 37%). Both combinations were well tolerated; the most common hematological toxicity was neutropenia, which occurred in 26% of patients in each treatment arm. CONCLUSIONS: These results suggest that gemcitabine plus docetaxel or irinotecan is well tolerated in patients with chemotherapy-naïve advanced NSCLC. The survival data with the combination gemcitabine-docetaxel are promising. Gemcitabine-docetaxel combination therapy may be particularly useful for patients who have experienced toxicities with a platinum regimen or in patients who may be more susceptible to platinum-related toxicity.

Adult↗
PubMed2004

Combined modality trials of the Cancer and Leukemia Group B in stage III non-small-cell lung cancer: analysis of factors influencing survival and toxicity.

BACKGROUND: Combined modality therapy (CMT) is the standard of care for patients with unresectable stage III non-small-cell lung cancer (NSCLC); however, insufficient data are available regarding prognostic factors in this disease setting. PATIENTS AND METHODS: Six hundred and ninety-four patients included in five trials conducted by the Cancer and Leukemia Group B evaluating CMT in stage III NSCLC were included in this analysis. The primary objective was to identify factors that were predictors of survival and selected radiation-related toxicities using Cox regression models and logistic regression analysis. RESULTS: The Cox model shows that performance status (PS) 1 [hazard ratio (HR) 1.24; 95% confidence interval (CI) 1.06-1.45; P=0.009] and thoracic radiation therapy (TRT) only (HR 1.58; 95% CI 1.22-2.05; P=0.001) predicted for poorer survival, while baseline hemoglobin >/=12 g/dl predicted for improved survival (HR 0.67; 95% CI 0.55-0.81; P </=0.0001). Multivariate logistic regression showed an increase of grade 3 + esophagitis among patients with PS 0 [odds ratio (OR) 1.7; 95% CI 1.1-2.7; P=0.029), >5% weight loss (OR 2.9; 95% CI 1.3-6.6; P=0.008) and patients receiving concurrent chemoradiation (OR 7.3; 95% CI 3.4-15.6; P=0.0001). CONCLUSIONS: Baseline hemoglobin and PS, as well as the use of CMT, have the greatest effect on survival in unresectable stage III NSCLC. The use of concurrent chemoradiation increases the risk of esophagitis, which remains the primary radiation-related toxicity.

Adult↗
PubMed2003

The role of ATF/CREB family members in cell growth, survival and apoptosis.

Programmed cell death is an integral part of the mechanisms regulating tissue homeostasis. Defects in the apoptotic signaling pathway are often associated with uncontrolled cell proliferation, high mutation rate and malignant transformation. Transcription factors, such as the mammalian ATF/CREB family of transcriptional regulators, have diverse functions in controlling cell proliferation and apoptosis. One particular ATF/CREB family member, ATFx, is an anti-apoptotic factor that plays an essential role in cell survival. Current observations indicate that one mechanism by which ATFx inhibits cell death and promotes cell survival is by disrupting signal transmission from activated "death receptors" to initiator caspases. A better understanding of ATFx function should provide new insight into the processes that control apoptotic cascades.

Activating Transcription Factors↗
PubMed2001

Promoter-specific activation defects by a novel yeast TBP mutant compromised for TFIIB interaction.

TFIIB is an RNA polymerase II general transcription factor (GTF) that has also been implicated in the mechanism of action of certain promoter-specific activators (see, for examples, [1-11]). TFIIB enters the preinitiation complex (PIC) primarily through contact with the TATA box binding protein (TBP), an interaction mediated by three TBP residues [12-14]. To study the role of TFIIB in transcription activation in vivo, we randomly mutagenized these three residues in yeast TBP and screened for promoter-specific activation mutants. One mutant bearing a single conservative substitution, TBP-E186D, is the focus of this study. As expected, TBP-E186D binds normally to the TATA box but fails to support the entry of TFIIB into the PIC. Cells expressing TBP-E186D are viable but have a severe slow-growth phenotype. Whole-genome expression analysis indicates that transcription of 17% of yeast genes are compromised by this mutation. Chimeric promoter analysis indicates that the region of the gene that confers sensitivity to the TBP-E186D mutation is the UAS (upstream activating sequence), which contains the activator binding sites. Most interestingly, other TBP mutants that interfere with different interactions (TFIIB, TFIIA, or the TATA box) and a TFIIB mutant defective for interaction with TBP all manifest distinct and selective promoter-specific activation defects. Our results implicate the entry of TFIIB into the PIC as a critical step in the activation of certain promoters and reveal diverse mechanisms of transcription activation.

Carrier Proteins↗
PubMed2001

Genetic analysis of TAF68/61 reveals links to cell cycle regulators.

In yeast, inactivation of certain TBP-associated factors (TAF(II)s) results in arrest at specific stages of the cell cycle. In some cases, cell cycle arrest is not observed because overlapping defects in other cellular processes precludes the manifestation of an arrest phenotype. In the latter situation, genetic analysis has the potential to reveal the involvement of TAF(II)s in cell cycle regulation. In this report, a temperature-sensitive mutant of TAF68/61 was used to screen for high-copy dosage suppressors of its growth defect. Ten genes were isolated: TAF suppressor genes, TSGs 1-10. Remarkably, most TSGs have either a genetic or a direct link to control of the G(2)/M transition. Moreover, eight of the 10 TSGs can suppress a CDC28 mutant specifically defective for mitosis (cdc28-1N) but not an allele defective for passage through start. The identification of these genes as suppressors of cdc28-1N has identified four unreported suppressors of this allele. Moreover, synthetic lethality is observed between taf68-9 and cdc28-1N. The isolation of multiple genes involved in the control of a specific phase of the cell cycle argue that the arrest phenotypes of certain TAF(II) mutants reflect their role in specifically regulating cell cycle functions.

CDC28 Protein Kinase, S cerevisiae↗
PubMed2001

A novel peptide recognition mode revealed by the X-ray structure of a core U2AF35/U2AF65 heterodimer.

U2 auxiliary factor (U2AF) is an essential splicing factor that recognizes the 3' splice site and recruits the U2 snRNP to the branch point. The X-ray structure of the human core U2AF heterodimer, consisting of the U2AF35 central domain and a proline-rich region of U2AF65, has been determined at 2.2 A resolution. The structure reveals a novel protein-protein recognition strategy, in which an atypical RNA recognition motif (RRM) of U2AF35 and the U2AF65 polyproline segment interact via reciprocal "tongue-in-groove" tryptophan residues. Complementary biochemical experiments demonstrate that the core U2AF heterodimer binds RNA, and that the interacting tryptophan side chains are essential for U2AF dimerization. Atypical RRMs in other splicing factors may serve as protein-protein interaction motifs elsewhere during spliceosome assembly.

Amino Acid Sequence↗
PubMed2001

Induction of apoptosis by a secreted lipocalin that is transcriptionally regulated by IL-3 deprivation.

Many hematopoietic cells undergo apoptosis when deprived of specific cytokines, and this process requires de novo RNA/protein synthesis. Using DNA microarrays to analyze interleukin-3 (IL-3)-dependent murine FL5.12 pro-B cells, we found that the gene undergoing maximal transcriptional induction after cytokine withdrawal is 24p3, which encodes a secreted lipocalin. Conditioned medium from IL-3-deprived FL5.12 cells contained 24p3 and induced apoptosis in naive FL5.12 cells even when IL-3 was present. 24p3 also induced apoptosis in a wide variety of leukocytes but not other cell types. Apoptotic sensitivity correlated with the presence of a putative 24p3 cell surface receptor. We conclude that IL-3 deprivation activates 24p3 transcription, leading to synthesis and secretion of 24p3, which induces apoptosis through an autocrine pathway.

Acute-Phase Proteins↗
PubMed2001

SAGA is an essential in vivo target of the yeast acidic activator Gal4p.

Despite major advances in characterizing the eukaryotic transcriptional machinery, the function of promoter-specific transcriptional activators (activators) is still not understood. For example, in no case have the direct in vivo targets of a transcriptional activator been unambiguously identified, nor has it been resolved whether activators have a single essential target or multiple redundant targets. Here we address these issues for the prototype acidic activator yeast Gal4p. Gal4p binds to the upstream activating sequence (UAS) of GAL1 and several other GAL genes and stimulates transcription in the presence of galactose. Previous studies have shown that GAL1 transcription is dependent on the yeast SAGA (Spt/Ada/GCN5/acetyltransferase) complex. Using formaldehyde-based in vivo cross-linking, we show that the Gal4p activation domain recruits SAGA to the GAL1 UAS. If SAGA is not recruited to the UAS, the preinitiation complex (PIC) fails to assemble at the GAL1 core promoter, and transcription does not occur. SAGA, but not other transcription components, is also recruited by the Gal4p activation domain to a plasmid containing minimal Gal4p-binding sites. Recruitment of SAGA by Gal4p and stimulation of PIC assembly is dependent on several SAGA subunits but not the SAGA histone acetyl-transferase (HAT) GCN5. Based on these and other results, we conclude that SAGA is an essential target of Gal4p that, following recruitment to the UAS, facilitates PIC assembly and transcription.

Acetyltransferases↗
PubMed2001

Twenty-two years of phase III trials for patients with advanced non-small-cell lung cancer: sobering results.

PURPOSE: To determine the changes in clinical trials and outcomes of patients with advanced-stage non-small-cell lung cancer (NSCLC) treated on phase III randomized trials initiated in North America from 1973 to 1994. PATIENTS AND METHODS: Phase III trials for patients with advanced-stage NSCLC were identified through a search of the National Cancer Institute's Cancer Therapy Evaluation Program database from 1973 to 1994, contact with Cooperative Groups, and by literature search of MEDLINE. Patients with advanced NSCLC treated during a similar time interval were also examined in the SEER database. Trends were tested in the number of trials, in the number and sex of patients entered on the trials, and in survival over time. RESULTS: Thirty-three phase III trials were initiated between 1973 and 1994. Twenty-four trials (73%) were initiated within the first half of this period (1973 to 1983) and accounted for 5,359 (64%) of the 8,434 eligible patients. The median number of patients treated per arm of the trials rose from 77 (1973 to 1983) to 121 (1984 to 1994) (P <.001). Five trials (15%) showed a statistically significant difference in survival between treatment arms, with a median prolongation of the median survival of 2 months (range, 0.7 to 2.7 months). CONCLUSION: Analysis of past trials in North America shows that the prolongation in median survival between two arms of a randomized study was rarely in excess of 2 months. Techniques for improved use of patient resources and appropriate trial design for phase III randomized therapeutic trials with patients with advanced NSCLC need to be developed.

Adult↗
PubMed2001

Expressing the human genome.

We have searched the human genome for genes encoding new proteins that may be involved in three nuclear gene expression processes: transcription, pre-messenger RNA splicing and polyadenylation. A plethora of potential new factors are implicated by sequence in nuclear gene expression, revealing a substantial but selective increase in complexity compared with Drosophila melanogaster and Caenorhabditis elegans. Although the raw genomic information has limitations, its availability offers new experimental approaches for studying gene expression.

Animals↗
PubMed2001

Identification and characterization of yUAP/Sub2p, a yeast homolog of the essential human pre-mRNA splicing factor hUAP56.

The human 56-kD U2AF(65)-associated protein (hUAP56), a member of the DExD/H box protein family of RNA-dependent ATPases, is required for the stable binding of U2 snRNP to the pre-mRNA branchpoint. Here we identify a highly conserved Saccharomyces cerevisiae homolog of hUAP56, yUAP/Sub2p. yUAP/Sub2p can be functionally substituted for by hUAP56 and, like its human counterpart, is an essential pre-mRNA splicing factor. yUAP/Sub2p is required for formation of the commitment complex, the precursor for U2 snRNP addition. In conjunction with previous studies, we conclude that at least two DExD/H box proteins, Prp5p and yUAP/Sub2p, mediate the U2 snRNP-branchpoint interaction.

Adenosine Triphosphatases↗
PubMed2001

Synergistic interaction between topotecan and microtubule-interfering agents.

PURPOSE: Topotecan is a topoisomerase I inhibitor with demonstrated anticancer activity in preclinical and clinical studies. The purpose of the present study was to evaluate drug-drug interactions in therapeutic regimens that would combine topotecan with microtubule-interfering agents, such as Taxol and vinblastine. METHODS: The cytotoxic activities of various drug combinations and schedules of administration were measured in a colon cancer cell line using the MTT assay. Western blot and flow cytometry were performed to determine the effects of Taxol and vinblastine on topoisomerase I and Bcl-xL protein levels and cell cycle distribution. RESULTS: Brief incubation of colon cancer cells with low concentrations of either Taxol or vinblastine increased the efficacy of a subsequent treatment with topotecan. Preincubation of cells with vinblastine or Taxol reduced by 10- to 40-fold the concentration of topotecan necessary to induce a 50% decrease in cell survival. The effects were maximal when the cells were treated for 5 h with microtubule-interfering agents and then incubated for 19 h in drug-free medium before the addition of topotecan. Under these conditions, both Taxol and vinblastine caused an increase in topoisomerase I protein levels, fraction of S phase cells, and extent of Bcl-xL phosphorylation immediately prior to the addition of topotecan. All these factors may contribute to the increased efficacy of topotecan observed with sequential therapy. CONCLUSION: Combinations of topotecan and microtubule-interfering agents result in synergistic anticancer activity when the drugs are administered sequentially. The promising preclinical data presented here encourage clinical testing of these drug combinations using a sequential schedule of administration.

Antineoplastic Agents↗
PubMed2001

High-dose doxorubicin, dexrazoxane, and GM-CSF in malignant mesothelioma: a phase II study-Cancer and Leukemia Group B 9631.

Doxorubicin is the most widely studied agent for the treatment of malignant mesothelioma. In conventional doses, the response rate is approximately 17%. Higher dose doxorubicin has been successfully employed in other tumor types. Dexrazoxane has been demonstrated to reduce the cardiac toxicity associated with long term, chronic use of doxorubicin. Based upon phase I data generated by the Cancer and Leukemia Group B (CALGB) indicating that doxorubicin at a dose of 120 mg/m(2) when combined with dexrazoxane and GM-CSF could be safely administered, the CALGB undertook a phase II study of high-dose doxorubicin in patients with malignant mesothelioma. Toxicity was excessive, necessitating protocol modification and ultimately protocol termination. There were no objective responses observed. We conclude that high-dose doxorubicin administered with dexrazoxane is unacceptably toxic in this patient population.

Adult↗