Hypoxia, DNA repair, and gene silencing
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1.Unified exact design with early stopping rules for single arm clinical trials with multiple endpoints
- 关键词:
- Go; no go decisions; multiple endpoints; biomarker endpoints;conditional power; early phase;PHASE-II TRIALS; 2-STAGE DESIGNS; EXPANSION COHORTS; TOXICITY; EFFICACY;BIVARIATE; SURROGATE; OUTCOMES
- Wei, Wei;Esserman, Denise;Kane, Michael;Zelterman, Daniel
- 《STATISTICAL METHODS IN MEDICAL RESEARCH》
- 2021年
- 30卷
- 7期
- 期刊
Adaptive designs are gaining popularity in early phase clinical trials because they enable investigators to change the course of a study in response to accumulating data. We propose a novel design to simultaneously monitor several endpoints. These include efficacy, futility, toxicity and other outcomes in early phase, single-arm studies. We construct a recursive relationship to compute the exact probabilities of stopping for any combination of endpoints without the need for simulation, given pre-specified decision rules. The proposed design is flexible in the number and timing of interim analyses. A R Shiny app with user-friendly web interface has been created to facilitate the implementation of the proposed design.
...2.Impact of structural ageism on greater violence against older persons:a cross-national study of56countries
- 关键词:
- SEXUAL ORIENTATION CONCEALMENT; UNITED-STATES; STIGMA; WORLD; IMMIGRATION; PREVALENCE; ATTITUDES; HIDDEN; ADULTS
- Chang, E-Shien;Monin, Joan K.;Zelterman, Daniel;Levy, Becca R.
- 《BMJ OPEN》
- 2021年
- 11卷
- 5期
- 期刊
Objective To determine the association between country-level structural ageism and prevalence of violence against older persons. Design Country-level ecological study. Setting Structural ageism data were drawn from the nationally representative World Values Survey 2010-2014 (WVS), global databases from the WHO, United Nations and the World Bank. Violence data were based on the Global Burden of Diseases (GBD) study 2017. Participants Analysis of 56 countries that represented 63.1% of the world's ageing population aged 60 and over across all six of WHO regions. Exposure Structural ageism, following established structural stigma measures, consisted of two components: (1) discriminatory national policies related to older persons' economic, social, civil and political rights, based on the four core components of human rights protection in Madrid International Plan of Action on Aging and (2) prejudicial social norms against older persons, measured by negative attitudes toward older persons in 56 national polls in WVS aggregated to country-level. These components were z scored and combined such that higher score indicated greater structural ageism. Main outcomes and measures Prevalence rates of violence per 100 000 persons aged 70 and over in each country was based on extensive epidemiological surveillance data, survey, clinical data and insurance claims in GBD and compiled by the Institute of Health Metrics and Evaluation, University of Washington. Results There was a wide variation in levels of structural ageism across countries. As predicted, structural ageism was significantly associated with the prevalence rates of violence in multivariate models (beta=205.7, SE=96.3, p=0.03), after adjusting for relevant covariates. Sensitivity analyses supported the robustness of our findings. That is, structural ageism did not predict other types of violence and other types of prejudice did not predict violence against older persons. Conclusions This study provides the first evidence of the association between higher structural ageism and greater violence against older persons across countries.
...3.Hypoxia Induces Resistance to EGFR Inhibitors in Lung Cancer Cells via Upregulation of FGFR1 and the MAPK Pathway
- 关键词:
- GEFITINIB; MUTATIONS; BIOLOGY; TARGET
- Lu, Yuhong;Liu, Yanfeng;Oeck, Sebastian;Zhang, Gary J.;Schramm, Alexander;Glazer, Peter M.
- 《CANCER RESEARCH》
- 2020年
- 80卷
- 21期
- 期刊
Development of resistance remains the key obstacle to the clinical efficacy of EGFR tyrosine kinase inhibitors (TKI). Hypoxia is a key microenvironmental stress in solid tumors associated with acquired resistance to conventional therapy. Consistent with our previous studies, we show here that long-term, moderate hypoxia promotes resistance to the EGFR TKI osimertinib (AZD9291) in the non-small cell lung cancer (NSCLC) cell line H1975, which harbors two EGFR mutations including T790M. Hypoxia-induced resistance was associated with development of epithelial-mesenchymal transition (EMT) coordinated by increased expression of ZEB-1, an EMT activator. Hypoxia induced increased fibroblast growth factor receptor 1 (FGFR1) expression in NSCLC cell lines H1975, HCC827, and YLR086, and knockdown of FGFR1 attenuated hypoxia-induced EGFR TKI resistance in each line. Upregulated expression of FGFR1 by hypoxia was mediated through the MAPK pathway and attenuated induction of the proapoptotic factor BIM. Consistent with this, inhibition of FGFR1 function by the selective small-molecule inhibitor BGJ398 enhanced EGFR TKI sensitivity and promoted upregulation of BIM levels. Furthermore, inhibition of MEK activity by trametinib showed similar effects. In tumor xenografts in mice, treatment with either BGJ398 or trametinib enhanced response to AZD9291 and improved survival. These results suggest that hypoxia is a driving force for acquired resistance to EGFR TKIs through increased expression of FGFR1. The combination of EGFR TKI and FGFR1 or MEK inhibitors may offer an attractive therapeutic strategy for NSCLC.Significance: Hypoxia-induced resistance to EGFR TKI is driven by overexpression of FGFR1 to sustain ERK signaling, where a subsequent combination of EGFR TKI with FGFR1 inhibitors or MEK inhibitors reverses this resistance.
...4.Oncometabolites suppress DNA repair by disrupting local chromatin signalling
- 关键词:
- HISTONE H3; DAMAGE; METHYLATION; IDH; DEMETHYLASES; MUTATIONS; FUMARATE;PROTEIN; CANCER; BREAKS
- Sulkowski, Parker L.;Oeck, Sebastian;Dow, Jonathan;Economos, Nicholas G.;Mirfakhraie, Lily;Liu, Yanfeng;Noronha, Katelyn;Bao, Xun;Li, Jing;Shuch, Brian M.;King, Megan C.;Bindra, Ranjit S.;Glazer, Peter M.
- 《NATURE》
- 2020年
- 582卷
- 7813期
- 期刊
Metabolites that are elevated in tumours inhibit the lysine demethylase KDM4B, resulting in aberrant hypermethylation of histone 3 lysine 9 and decreased homology-dependent DNA repair.Deregulation of metabolism and disruption of genome integrity are hallmarks of cancer(1). Increased levels of the metabolites 2-hydroxyglutarate, succinate and fumarate occur in human malignancies owing to somatic mutations in the isocitrate dehydrogenase-1 or -2 (IDH1 or IDH2) genes, or germline mutations in the fumarate hydratase (FH) and succinate dehydrogenase genes (SDHA, SDHB, SDHC and SDHD), respectively(2-4). Recent work has made an unexpected connection between these metabolites and DNA repair by showing that they suppress the pathway of homology-dependent repair (HDR)(5,6) and confer an exquisite sensitivity to inhibitors of poly (ADP-ribose) polymerase (PARP) that are being tested in clinical trials. However, the mechanism by which these oncometabolites inhibit HDR remains poorly understood. Here we determine the pathway by which these metabolites disrupt DNA repair. We show that oncometabolite-induced inhibition of the lysine demethylase KDM4B results in aberrant hypermethylation of histone 3 lysine 9 (H3K9) at loci surrounding DNA breaks, masking a local H3K9 trimethylation signal that is essential for the proper execution of HDR. Consequently, recruitment of TIP60 and ATM, two key proximal HDR factors, is substantially impaired at DNA breaks, with reduced end resection and diminished recruitment of downstream repair factors. These findings provide a mechanistic basis for oncometabolite-induced HDR suppression and may guide effective strategies to exploit these defects for therapeutic gain.
...5.Tumor-Targeted, Cytoplasmic Delivery of Large, Polar Molecules Using a pH-Low Insertion Peptide
- 关键词:
- pHLIP; tumor-targeted drug delivery; tumor acidity; transmembraneinsertion; membrane permeability; drug size;LIPID-BILAYER; MEMBRANE INSERTION; DRUG-DELIVERY; NUCLEIC-ACIDS;IN-VIVO; PHLIP; CELL; TRANSLOCATION; PERMEABILITY; HELIX
- Svoronos, Alexander A.;Bahal, Raman;Pereira, Mohan C.;Barrera, Francisco N.;Deacon, John C.;Bosenberg, Marcus;DiMaio, Daniel;Glazer, Peter M.;Engelman, Donald M.
- 《MOLECULAR PHARMACEUTICS》
- 2020年
- 17卷
- 2期
- 期刊
Tumor-targeted drug delivery systems offer not only the advantage of an enhanced therapeutic index, but also the possibility of overcoming the limitations that have largely restricted drug design to small, hydrophobic, "drug-like" molecules. Here, we explore the ability of a tumor-targeted delivery system centered on the use of a pH-low insertion peptide (pHLIP) to directly deliver moderately polar, multi-kDa molecules into tumor cells. A pHLIP is a short, pH responsive peptide capable of inserting across a cell membrane to form a transmembrane helix at acidic pH. pHLIPs target the acidic tumor microenvironment with high specificity, and a drug attached to the inserting end of a pHLIP can be translocated across the cell membrane during the insertion process. We investigate the ability of wildtype pHLIP to deliver peptide nucleic acid (PNA) cargoes of varying sizes across lipid membranes. We find that pHLIP effectively delivers PNAs up to similar to 7 kDa into cells in a pH-dependent manner. In addition, pHLIP retains its tumor-targeting capabilities when linked to cargoes of this size, although the amount delivered is reduced for PNA cargoes greater than similar to 6 kDa. As drug-like molecules are traditionally restricted to sizes of similar to 500 Da, this constitutes an order-of-magnitude expansion in the size range of deliverable drug candidates.
...6.Suppressing miR-21 activity in tumor-associated macrophages promotes an antitumor immune response
- 关键词:
- QUANTITATIVE-ANALYSIS; T-CELLS; CANCER; MICRORNA-21; ACTIVATION;EXPRESSION; INFLAMMATION; MECHANISMS; CONTRIBUTE; INDUCTION
- Sahraei, Mahnaz;Chaube, Balkrishna;Liu, Yuting;Sun, Jonathan;Kaplan, Alanna;Price, Nathan L.;Ding, Wen;Oyaghire, Stanley;Garcia-Milian, Rolando;Mehta, Sameet;Reshetnyak, Yana K.;Bahal, Raman;Fiorina, Paolo;Glazer, Peter M.;Rimm, David L.;Fernandez-Hernando, Carlos;Suarez, Yajaira
- 《JOURNAL OF CLINICAL INVESTIGATION》
- 2019年
- 129卷
- 12期
- 期刊
microRNA-21 (miR-21) is the most commonly upregulated miRNA in solid tumors. This cancer-associated microRNA (oncomiR) regulates various downstream effectors associated with tumor pathogenesis during all stages of carcinogenesis. In this study, we analyzed the function of miR-21 in noncancer cells of the tumor microenvironment to further evaluate its contribution to tumor progression. We report that the expression of miR-21 in cells of the tumor immune infiltrate, and in particular in macrophages, was responsible for promoting tumor growth. Absence of miR-21 expression in tumor-associated macrophages (TAMs), caused a global rewiring of their transcriptional regulatory network that was skewed toward a proinflammatory angiostatic phenotype. This promoted an antitumoral immune response characterized by a macrophage-mediated improvement of cytotoxic T-cell responses through the induction of cytokines and chemokines, including IL-12 and C-X-C motif chemokine 10. These effects translated to a reduction in tumor neovascularization and an induction of tumor cell death that led to decreased tumor growth. Additionally, using the carrier peptide pH (low) insertion peptide, we were able to target miR-21 in TAMs, which decreased tumor growth even under conditions where miR-21 expression was deficient in cancer cells. Consequently, miR-21 inhibition in TAMs induced an angiostatic and immunostimulatory activation with potential therapeutic implications.
...7.A parametric meta-analysis
- 关键词:
- Bayesian estimator; citicoline; distribution of p-values; standardizedmean difference;ACUTE ISCHEMIC-STROKE; WEIGHTED Z-TEST; COMBINING PROBABILITIES;PROPORTION; CITICOLINE; R(EQUIVALENT)
- Yu, Chang;Zelterman, Daniel
- 《STATISTICS IN MEDICINE》
- 2019年
- 38卷
- 21期
- 期刊
In a meta-analysis, we assemble a sample of independent, nonidentically distributed p-values. The Fisher's combination procedure provides a chi-squared test of whether the p-values were sampled from the null uniform distribution. After rejecting the null uniform hypothesis, we are faced with the problem of how to combine the assembled p-values. We first derive a distribution for the p-values. The distribution is parameterized by the standardized mean difference (SMD) and the sample size. It includes the uniform as a special case. The maximum likelihood estimate (MLE) of the SMD can then be obtained from the independent, nonidentically distributed p-values. The MLE can be interpreted as a weighted average of the study-specific estimate of the effect size with a shrinkage. The method is broadly applicable to p-values obtained in the maximum likelihood framework. Simulation studies show that our method can effectively estimate the effect size with as few as 6 p-values in the meta-analyses. We also present a Bayes estimator for SMD and a method to account for publication bias. We demonstrate our methods on several meta-analyses that assess the potential benefits of citicoline for patients with memory disorders or patients recovering from ischemic stroke.
...8.A two-stage phase II clinical trial design with nested criteria for early stopping and efficacy
- 关键词:
- curtailed sampling; expected sample size; expected trial duration;minimax design;SAFETY
- DeVeaux, Michelle;Kane, Michael;Wei, Wei;Zelterman, Daniel
- 《PHARMACEUTICAL STATISTICS》
- 2019年
- 18卷
- 6期
- 期刊
We propose a two-stage design for a single arm clinical trial with an early stopping rule for futility. This design employs different endpoints to assess early stopping and efficacy. The early stopping rule is based on a criteria determined more quickly than that for efficacy. These separate criteria are also nested in the sense that efficacy is a special case of, but usually not identical to, the early stopping endpoint. The design readily allows for planning in terms of statistical significance, power, expected sample size, and expected duration. This method is illustrated with a phase II design comparing rates of disease progression in elderly patients treated for lung cancer to rates found using a historical control. In this example, the early stopping rule is based on the number of patients who exhibit progression-free survival (PFS) at 2 months post treatment follow-up. Efficacy is judged by the number of patients who have PFS at 6 months. We demonstrate our design has expected sample size and power comparable with the Simon two-stage design but exhibits shorter expected duration under a range of useful parameter values.
...9.Cediranib suppresses homology-directed DNA repair through down-regulation of BRCA1/2 and RAD51
- 关键词:
- POLY(ADP-RIBOSE) POLYMERASE; CANCER; PROTEIN; OLAPARIB; RECOMBINATION;INHIBITION; EXPRESSION; POTENT; TUMORS; CELLS
- Kaplan, Alanna R.;Gueble, Susan E.;Liu, Yanfeng;Oeck, Sebastian;Kim, Hoon;Yun, Zhong;Glazer, Peter M.
- 《SCIENCE TRANSLATIONAL MEDICINE》
- 2019年
- 11卷
- 492期
- 期刊
Combining the anti-angiogenic agent cediranib with the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib improves progression-free survival compared to olaparib alone in ovarian cancer patients through an unknown mechanism. PARP inhibitors are used primarily in the treatment of patients with DNA repair-associated (BRCA1/2) mutated cancers because these mutations cause a deficit in homology-directed DNA repair (HDR) that confers sensitivity to these agents. However, the combination of cediranib and olaparib was effective in patients without BRCA1/2 mutations. We report here that cediranib confers sensitivity to olaparib by down-regulating HDR in tumor cells. This occurs partially as a result of cediranib inducing hypoxia, which suppresses expression of the HDR factors BRCA1/2 and RAD51 recombinase (RAD51). However, we also observed that cediranib has a direct effect on HDR independent of its ability to induce tumor hypoxia. This direct effect occurs through platelet-derived growth factor receptor (PDGFR) inhibition, activation of protein phosphatase 2A (PP2A), and E2F transcription factor 4 (E2F4)/RB transcriptional corepressor like 2 (RB2/p130)-mediated repression of BRCA1/2 and RAD51 gene expression. This down-regulation was seen in mouse tumor xenografts but not in mouse bone marrow, providing a therapeutic window for combining cediranib and olaparib in cancer therapy. Our work reveals a treatment strategy by which DNA repair can be manipulated in human tumors to induce synthetic lethality, broadening the potential therapeutic scope of cediranib based on its activity as a DNA repair inhibitor.
...10.Electron-Mediated Aminyl and Iminyl Radicals from C5 Azido-Modified Pyrimidine Nucleosides Augment Radiation Damage to Cancer Cells
- 关键词:
- THYMIDINE KINASE; CLICK CHEMISTRY; DNA; REACTIVITY; GENE; AZT;RADIOSENSITIZERS; TRIPHOSPHATE; ABSTRACTION; ATTACHMENT
- Wen, Zhiwei;Peng, Jufang;Tuttle, Paloma R.;Ren, Yaou;Garcia, Carol;Debnath, Dipra;Rishi, Sunny;Hanson, Cameron;Ward, Samuel;Kumar, Anil;Liu, Yanfeng;Zhao, Weixi;Glazer, Peter M.;Liu, Yuan;Sevilla, Michael D.;Adhikary, Amitava;Wnuk, Stanislaw F.
- 《ORGANIC LETTERS》
- 2018年
- 20卷
- 23期
- 期刊
Two classes of azido-modified pyrimidine nucleosides were synthesized as potential radiosensitizers; one class is 5-azidomethyl-2'-deoxyuridine (AmdU) and cytidine (AmdC), while the second class is 5-(1-azidovinyl)-2'-deoxyuridine (AvdU) and cytidine (AvdC). The addition of radiation-produced electrons to C5-azido nucleosides leads to the formation of pi-aminyl radicals followed by facile conversion to sigma-iminyl radicals either via a bimolecular reaction involving intermediate alpha-azidoalkyl radicals in AmdU/AmdC or by tautomerization in AvdU/AvdC. AmdU demonstrates effective radiosensitization in EMT6 tumor cells.
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