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DNA Decatenation Study

DNA Decatenation Study

BRCA1 Participates in DNA Decatenation Zhenkun Lou, Katherine Minter-Dykhouse & Junjie Chen The tumor suppressor BRCA1 has an important function in the maintenance of genomic stability. Increasing evidence suggests that BRCA1 regulates cell cycle checkpoints and DNA repair after DNA damage. However, little is known about its normal function in the absence of DNA damage. Here we show that BRCA1 interacts and colocalizes with topoisomerase IIa in S phase cells. Similar to cells treated with the topoisomerase IIa inhibitor ICRF-193,…

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Topoisomerase I Not Simply Adjusting Genome Topology

Topoisomerase I Not Simply Adjusting Genome Topology

Topoisomerases are well known to be essential for all aspects of DNA function, from replication to repair and particularly in transcription. For this reason, they have for many years been excellent DNA damaging agents that display selectively for tumor cells. A relatively recent finding has come to light that involves topoisomerase I and induction of cellular senescence. Cellular senescence is a form of tumor suppression that puts cells in a more or less permanent proliferative arrest. It is induced by…

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Upcoming Closure May 4-18

Upcoming Closure May 4-18

Our business and shipping facilities will be closed May 4-18 while our staff visits with collaborators in Europe. During this time we will be answering voicemails and emails, so please do continue to contact us. Our offices will be resume our normal product shipping regimen on May 23. Thank you!

Rapid Transport of Novel Topo II Inhibitor into Cancer Cells

Rapid Transport of Novel Topo II Inhibitor into Cancer Cells

F14512, a Potent Antitumor Agent Targeting Topoisomerase II Vectored into Cancer Cells via the Polyamine Transport System Jean-Marc Barret, Anna Kruczynski, Stéphane Vispé, et al. Abstract The polyamine transport system (PTS) is an energy-dependent machinery frequently overactivated in cancer cells with a high demand for polyamines. We have exploited the PTS to selectively deliver a polyamine-containing drug to cancer cells. F14512 combines an epipodophyllotoxin core-targeting topoisomerase II with a spermine moiety introduced as a cell delivery vector. The polyamine tail…

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Doxorubicin: A Preclinical Study

Doxorubicin: A Preclinical Study

Sequencing of Type I Insulin-Like Growth Factor Receptor Inhibition Affects Chemotherapy Response In vitro and In vivo Xianke Zeng,1,2 Deepali Sachdev,2 Hua Zhang,2 Martine Gaillard-Kelly,3 and DouglasYee1,2 Abstract Purpose: The aim of this study was to determine the optimal sequence of combining anti-type I insulin-like growth factor receptor (IGF1R) antibodies with chemotherapeutic drugs in cancer cells in vitro and in vivo. Experimental Design: MCF-7 and LCC6 cells were treated with subcytotoxic concentrations of doxorubicin with or without anti-IGF1R antibodies (scFv-Fc…

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TopoGEN Activity Assays: Topo II Inhibitor Study

TopoGEN Activity Assays: Topo II Inhibitor Study

Thanatop: A Novel 5-Nitrofuran that Is a Highly Active, Cell-Permeable Inhibitor of Topoisomerase II Abstract A series of nitrofuran-based compounds were identified as inhibitors of estrogen signaling in a cell-based, high-throughput screen of a diverse library of small molecules. These highly related compounds were subsequently found to inhibit topoisomerase II in vitro at concentrations similar to that required for the inhibition of estrogen signaling in cells. The most potent nitrofuran discovered is f10-fold more active than etoposide phosphate, a topoisomerase…

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Gyrase B Inhibitor Potential HIV Treatment

Gyrase B Inhibitor Potential HIV Treatment

Gyrase B Inhibitor Impairs HIV-1 Replication by Targeting Hsp90 and the Capsid Protein Chemical genetics is an emerging approach to investigate the biology of host-pathogen interactions. We screened several inhibitors of ATP-dependent DNA motors and detected the gyrase B inhibitor coumermycin A1 (C-A1) as a potent antiretroviral. C-A1 inhibited HIV-1 integration and gene expression from acutely infected cell, but the two activities mapped to distinct targets. Target discovery identified Hsp90 as the C-A1 target affecting viral gene expression. Chromatin immunoprecipitation…

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Topo I Assay Kit Aids Breast Cancer Study

Topo I Assay Kit Aids Breast Cancer Study

Epidermal Growth Factor-Induced Heparanase Nucleolar Localization Augments DNA Topoisomerase I Activity in Brain Metastatic Breast Cancer Abstract Identification of molecular mechanisms responsible for brain metastatic breast cancer (BMBC) is imperative to develop novel therapies. However, current understanding of the molecular circuitry that governs BMBC dissemination remains fragmentary. Heparanase (HPSE) is the only functional mammalian endoglycosidase whose activity correlates with cancer metastasis, angiogenesis, and the reduced postoperative survival of cancer patients, making it an active target for anticancer therapeutics. We hypothesized…

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DNA Cleavage Assay Aids The Clinical Search for New Top1 Inhibitors

DNA Cleavage Assay Aids The Clinical Search for New Top1 Inhibitors

DNA cleavage assay for the identification of topoisomerase I inhibitors The inhibition of DNA topoisomerase I (Top1) has proven to be a successful approach in the design of anticancer agents. However, despite the clinical successes of the camptothecin derivatives, a significant need for less toxic and more chemically stable Top1 inhibitors still persists. Here, we describe one of the most frequently used protocols to identify novel Top1 inhibitors. These methods use uniquely 3′-radiolabeled DNA substrates and denaturing polyacrylamide gel electrophoresis…

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TopoGEN Topoisomerase Antibodies Used in Chemotherapy Study

TopoGEN Topoisomerase Antibodies Used in Chemotherapy Study

Topoisomerase levels determine chemotherapy response in vitro and in vivo Darren J. Burgess*, Jason Doles†, Lars Zender*, Wen Xue*, Beicong Ma*‡, W. Richard McCombie*, Gregory J. Hannon*‡, Scott W. Lowe*‡§, and Michael T. Hemann*† *Cold Spring Harbor Laboratory and ‡Howard Hughes Medical Institute, 1 Bungtown Road, Cold Spring Harbor, NY 11724; and †Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139 Communicated by Michael H. Wigler, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, April 14, 2008 (received…

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