bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2632: Syrbactin, a novel proteasome inhibitor class, induces apoptosis and autophagy in neuroblastoma
Authors: Bachmann Andre S. , Archer Crystal R. , Koomoa Dana-Lynn T. , Clerc Jerome , Shimizu Mariko , Kaiser Markus , Schellenberg Barbara , Dudler Robert
Published: February 2011

Syrbactins belong to a new class of proteasome inhibitors which include syringolins and glidobactins. These small molecules are structurally distinct from other, well-established proteasome inhibitors, and bind the eukaryotic 20S proteasome by a novel mechanism. In this study, we examined the effects of syringolin A (SylA) and glidobactin A (GlbA) as well as two synthetic SylA-analogs (SylA-PEG and SylA-LIP) in human neuroblastoma (SK-N-SH), human multiple myeloma (MM1.S, MM1.RL, and U266), and human ovarian cancer (SKOV3) cells. While all four syrbactins inhibited cell proliferation in a dose-dependent manner, GlbA was most potent in both dexamethasone-sensitive MM1.S cells (IC50: 0.004 µM) and dexamethasone-resistant MM1.RL cells (IC50: 0.005 µM). Syrbactins also inhibited the chymotrypsin-like proteasome activity in a dose-dependent fashion, and GlbA was most effective in SK-N-SH cells (IC50: 0.015 µM). The GlbA-promoted inhibition of proteasomal activity in SK-N-SH cells resulted in the accumulation of ubiquitinated proteins and tumor suppressor protein p53, and led to apoptotic cell death. Strikingly, GlbA treatment also promoted the activation of Akt/PKB via phosphorylation at residue Ser473 and induced autophagy as judged by the presence of the lipidated form of microtubule-associated protein 1 light chain 3 (LC3) and autophagosomes. Collectively, our data suggest that syrbactins belong to a new and effective proteasome inhibitor class which promotes cell death. Proteasome inhibition is a promising strategy for targeted anticancer therapy and syrbactins are a new class of inhibitors which provide a structural platform for the development of novel, proteasome inhibitor-based drug therapeutics.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2632.
Abstract 2634: Combination of HSP90 and mTOR inhibition promotes pancreatic cancer growth inhibition
Authors: Weekes Colin D. , Ciobanu Madalina
Published: February 2011

The molecular determinants of resistance to mTOR targeted therapies remain unspecified. Genomic analysis has demonstrated that a number of gene families promoting intracellular signal transduction are overexpressed in mTOR resistant human pancreas explant xenografts. Heat shock proteins serve as molecular chaperone for many of the proteins implicated in the analysis. As such, it was hypothesized that proximal intracellular signal transduction inhibition with a HSP90 inhibitor could overcome inherent pancreas cancer resistance to mTOR inhibitors. Fourteen human pancreatic cell lines have been analyzed with respect to their proliferative capacity upon exposure to RAD001 (mTOR inhibitor) and AUY922 (HSP90 inhibitor), both as single agents and in combination. In vitro analysis with CalcuSyn® software demonstrates synergistic antiproliferative effects of these two drugs. For example, combination index (CI) values ranging from 0.01 to 0.5 were observed when the mTOR resistant cell line PANC02.03 was treated with the combination of RAD001 and AUY922. In vivo treatment of the L3.6 xenograft model with AUY922 and RAD001 resulted in preferential tumor growth inhibition of the combination relative to either drug alone. These effects were associated with the inhibition of the pI3K/AKT/mTOR and the ERK pathways. In summary, proximal signal transduction inhibition by a HSP90 may overcome inherent pancreas cancer mTOR inhibitor resistance. Future work is designed to extend these finding and to determine the specific pathways that are necessary for the observed growth inhibition.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2634.
Abstract 264: EGFR endocytosis after binding of different ligands
Authors: Grøvdal Lene M. , Henriksen Lasse , Grandal Michael V. , Knudsen Stine LJ , van Deurs Bo
Published: February 2011

The EGF receptor (EGFR) is activated by binding of ligand, leading to both signaling and receptor endocytosis. This endocytosis can lead to receptor downregulation, or recycling. Although EGFR regulation has received much attention, most studies have been performed using either EGF or TGFα. We described EGFR endocytosis upon binding of four additional ligands. Even though all ligands induce internalization, degradation of the receptor is dependent on the nature of the ligand bound. We have shown that the different ligands vary in levels of EGFR activation, receptor ubiquitination, and also in pH-stability of receptor-ligand interaction. We found that whereas HB-EGF and betacellulin are strong inducers of EGFR degradation, TGFα and epiregulin mostly allow for recycling of the EGFR. Amphiregulin also allows for recycling of the EGFR, but by a slower pathway. EGF leads to both recycling and degradation of the EGFR. We now show that, in addition to intracellular sorting in endosomes, the mechanism of internalization of the EGFR from the plasma membrane also differs depending on which ligand is bound.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 264.
Abstract 2642: Identification and characterization of selective inhibitors of ubiquitin specific protease 7
Authors: Reverdy Céline , Conrath Susan , Lopez Roman , Planquette Cécile , Collura Vincent , Guedat Philippe , Delansorne Rémi , Daviet Laurent , Colland Frédéric
Published: February 2011

Regulated protein turnover is primarily controlled by the ubiquitin-proteasome system. The only marketed drug related to the ubiquitin-proteasome system, bortezomib, is acting as a proteasome inhibitor and has been approved for the treatment of some hematological cancers. Targeting the upstream ubiquitin conjugation/deconjugation system carries out promises of therapeutics with increased specificity and selectivity. Ubiquitin-specific proteases (USP) are involved in the deubiquitination of specific target substrates regulating their stability, subcellular localization and/or activation status. USP represent a drugable target class due to their thiol-protease catalytic core which is amenable to pharmacological inhibition by small molecules. A genome-wide RNAi screen of the catalytically active human USPs in cancer-relevant cellular models and phenotypic assays allowed us to identify USP7/HAUSP as promising cancer target. Fluorescence-based screening assays using optimized USP substrates including various ubiquitin derivatives (ubiquitin precursor, branched ubiquitin chains) as well as specific, physiological substrates were developed. High-throughput screening performed on our chemically diverse library followed by different optimization programs resulted in the discovery of several series as novel USP7 inhibitors. Our progress made towards the specificity issue will be presented here with the identification of the first USP7-specific series. These will help further validate this novel class of molecular targets and may provide a structural basis for the development of new anticancer drugs.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2642.
Abstract 2643: A highly versatile nanoplatform for the treatment and imaging of cancers
Authors: Lam Kit S. , Juntao Luo , Xiao Kai , Li Yuan-pei , Lee Joyce , Yao Nianhuan , Xiao Wenwu , Wang Yabg , Kent Michael , Cheng Holland , Xing Li , Liu Gangyu , Tan Yihrong
Published: February 2011

We have recently developed a novel amphiphilic polymer (telodendrimer), comprised of linear polyethylene glycol and cholic acid cluster, that can self-assemble under aqueous condition to form stable micelles. We have succeeded in loading the nanoparticles with several different hydrophobic drugs. These include paclitaxel, etoposide, vincristine, and dexamethasone. This nanoplatform is highly versatile. Particle size can be readily tuned by varying the configuration and composition of the telodendrimer. Nanoparticles of various sizes loaded with DiD, a near infra-red hydrophobic dye, were prepared and their biodistribution evaluated in nude mice bearing ovarian cancer xenografts. Particles smaller than 60 nm preferentially targeted the tumors whereas particles at 150nm were found to concentrate at the liver and lung but with low tumor uptake. The surface chemistry can be easily modified by tethering various acidic or basic peptides to the distal polyethylene glycol tail of the telodendrimers. Undesirable liver uptake was very high for those nanoparticles with high surface charges, either positive or negative. In contrast, liver uptake was very low but tumor uptake was very high when the surface charge was neutral. Ligation of tumor targeting ligands to the particle surface further improved tumor targeting and intracellular uptake at the tumor site. In addition to xenograft models, we have also demonstrated that the nanoparticles could preferentially target early spontaneous mammary tumors of PyV-MT transgenic mice. We have just completed a Phase I study of placiltaxel-loaded nanoparticles in companion dogs with lymphoma and showed that the drug is safe.

The nanoparticles are stable both in vitro and in vivo. Additional stability of the nanoparticles can be achieved by chemical stitching of adjacent telodendrimers after micelle formation. The telodendrimer can be easily radioiodinated with [I-131]-PIB, and the resulting radio-labeled nanoparticles can be used for both radioimaging and radiotherapy. Very recently, we have succeeded in loading the nanoparticles with bortezomib (a proteasome inhibitor) to high level. We are currently evaluating the in vivo anti-tumor activities of the bortezomib nanoformulation in xenograft lymphoma as well as ovarian cancer models in nude mice. This new class of nanotherapeutics shows great promise in future cancer therapy and imaging.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2643.
Abstract 2649: Whole body vibration effects on binding kinetics and targeting of near-infrared dye conjugated bisphosphonate
Authors: Papineni Rao V. , Orton Sean , McLaughlin William , Vizard Douglas , Ji Tao , Schmitthenner Hans , Pan Jingyi
Published: February 2011

A non-invasive means of targeting bisphophonate to specific skeletal sites, along with the passive binding/decay kinetics of the near-infrared bisphosphanate analog to the skeleton are determined. Bone is the third common site where breast, lung, and prostate cancer cells spread and metastasize. Debilitating pain is the major complication resulting from bone metastases in nearly 70% of the patients. The palliative bone pain management includes the bisphosphanate therapy. Bisphosphonates, a potent inhibitor of bone resorption, gives both pain relief and improves bone health. However these medications result in complications such as bisphosphonate-related osteonecrosis of the jaw (BRONJ). Combinations of low-risk exercise programs along with reduced drug dosage are a likely alternative to counter such drug-related side effects. Site-selective skeletal targeting of bisphosphonates, if feasible, is however ideal to overcome drug-related side effects. We utilized whole body vibration (WBV), to target NIR dye conjugate bisphosphonate to specific skeletal sites. Using near-infrared (NIR) fluorescence imaging, both the targeting and the passive binding of the bisphosphonate in vivo was determined. Vibration loading, utilizing whole body vibration (WBV) was performed on twelve mice by subjecting them to vibration frequency of 35 Hz for fifteen min (5-10 times/week) duration. Alendronate was conjugated to near-infrared tricarbocyanine, cyclic enamine-functionalized dye, and was injected intravenously after 21-day exercise regime. Yet to be reported, we show that NIR-alendronate probe bound to the lumbar L6 vertebrae, resultant of direct high-frequency WBV stimulation. This is besides several other specific targeting sites. Further, both the passive binding and the decay kinetics of the NIR signal at the skeleton was determined in a six-week non-invasive longitudinal study of mouse pups. This provides opportunity to utilize such approaches in future translational studies in assessing the role of bisphosphonates in preventing spreading of cancer cells at other secondary sites, especially bone. The targeted drug binding in response to the vibratory protocol also provides hope in the development of whole body vibration (WBV) as a bisphosphonate-therapeutic aid. Further, to develop strategies in reducing the drug dosage in treatment of other morbidity factors that stem from complications from bone metastases.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2649.
Abstract 2653: Thermally targeted delivery of an acid-labile derivative of doxorubicin by elastin-like polypeptide
Authors: Robinson Leslie , Kratz Felix , Raucher Drazen
Published: February 2011

Doxorubicin (Dox) is an anthracycline used in the treatment of many types of cancer. It intercalates into the strands of DNA to inhibit the progression of topoisomerase II, stopping the cell from replicating. The side effects, however, are severe and include neutropenia, alopecia, nausea, myelosuppression, and cardiotoxicity. The drug is nonspecific; as a result, high doses are needed to treat cancer cells. These high doses are inadvertently harmful to normal cells. Therefore, there is a need for an efficient drug delivery system in order to deliver doxorubicin to the tumor site. Our lab has developed a macromolecular carrier that can provide this targeted delivery. This elastin-like polypeptide (ELP) is thermally responsive as it remains in solution at physiological temperature and aggregates upon heating at 42 °C.

The N-terminus of ELP was modified with three different cell penetrating peptides (CPPs) - Bac, Tat, and SynB1. These peptides are derived from the bactenecin family of antimicrobial peptides, truncated version of the HIV-1 Tat protein, and porcine leukocytes, respectively. This study compared the efficiency of these three CPP-ELP carriers to deliver doxorubicin to the cells. ELP was attached to a hydrazone derivative of doxorubicin (DOXO) by conjugation of a 6-maleimidocaproyl moiety on the drug with a terminal cysteine residue on ELP. This linker allows the drug to be cleaved at acidic pH in the cell. The three CPP-ELP-DOXO conjugates had transition temperatures within the range of 38-42°C. All three carriers of DOXO inhibited MCF-7 breast cancer cell proliferation 2-fold more at 42 °C than at 37 °C, indicating that the hyperthermia induced phase transition of ELP does increase the local concentration of the drug. Inhibition of cell proliferation may be due to apoptosis, since apoptosis was enhanced 2.3-fold in MCF-7 cells when SynB1-ELP-DOXO aggregation was induced with hyperthermia. CPP-ELP-DOXO accumulated in cells to the same level as free Dox. Confocal imaging showed that when cells were treated with any of the three CPP-ELP-DOXO derivatives, Dox localized in the nucleus, similar to the free Dox. The results suggest that CPP-ELP-DOXO conjugates may provide a means to thermally target solid tumors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2653.
Abstract 2656: Association of daunorubicin to a lipidic nanoemulsion (NEM-ODNR) - in vivo tumor growth inhibition
Authors: Contente Thais C. , Kretzer Iara F. , Maria Durvanei A. , Capeto Tathiana , Fock Ricardo , Maranhao Raul C.
Published: February 2011

After injection into blood stream an artificial nanoemulsion (NEm) that mimics LDL composition binds to LDL receptors and concentrates in tumor tissues that show LDL receptor overexpression. NEm has been used as carrier to target drugs against neoplastic tissues and was shown to diminish toxicity while increase tumoral inhibition growth in murine models, showing more effective and selectiveness. Daunorrubicin (DNR) is an anthracycline antibiotic that possesses broad spectrum antineoplastic activity, and is one of the most important anticancer agents in use. However, clinical utility is hampered by cumulative, dose limiting cardiotoxicity, myelosupression, and the development of drug resistence. Derivative form of daunorubicin oleate (ODNR) was synthesized and associated to NEM by prolonged ultrassonication and ultracentrifugation Antitumor activity of NEM-ODNR were tested in B16F10 melanoma bearing mice and compared with commercial formulation (DNR) and control group (saline). Tumor growth, presence of metastatic nodes and hematological profile were evaluated. The cytotoxicity of NEm-ODNR was diminished by five times compared to DNR. In dose acute toxicity studies the NEm-ODNR tolerability was 72-times higher compared to commercial DNR. The tumor growth inhibition rate for NEM-ODNR was over 35% when compared to DNR and 59% compared to saline (p < 0,001). There was a significant reduction in animals bearing metastasis for NEM associated treated group (30%) in comparison to the commercial treated (80%). In control group all animals developed metastatic tumors. Hematological profile showed that NEM-ODNR treatment had a 15% raise for red blood cells, compared to 29% of reduction for DNR, 25% of reduction to white blood cells compared to 55% for DNR and 45% reduction of platelets compared to 57% for DNR. Flow cytometry suggested greater antitumor activity for NEm-ODNR group showing remarkable arrest (47%) on DNA fragmentation phase of cell cycle compared to 26% to DNR. Those tests are essential for evaluating the NEM-ODNR formulation and its implementation of future clinical trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2656.
Abstract 2657: Development of melanoma target-specific drug delivery system
Authors: Ndinguri Margaret , Fields Gregg , Lauer-Fields Janelle
Published: February 2011

While many approved drugs are well-tolerated by most biological systems, numerous drugs could utilize advanced delivery systems to direct them where needed and minimize breakdown as they circulate through the body. We are exploring targeted delivery of doxorubicin using Nanotechnology-based Drug Delivery Systems (nanoDDSs). NanoDDSs have gained recent popularity but they do not posses inherent targeting capabilities. Nanoparticles and micelles can be modified in many ways allowing for specific targeted delivery. Over expression of CD44 in metastatic melanoma and a variety of tumor stem cells has made this receptor an ideal candidate for targeted drug delivery. The sequence to which CD44 binds within the type IV collagen triple helix has been identified as α1(IV)1263-1277. The incorporation of α1(IV)1263-1277 into drug loaded liposomes confers targeting selectivity against cancer cell lines that have CD44 receptors. Doxorubicin is one of the FDA approved drugs widely used for treatment of many types of cancers. The specificity of this drug can be enhanced by targeted delivery to the cancer cells, thereby minimizing deleterious side effects. In this study we present novel targeted doxorubicin-loaded liposomes and investigate the tumor cell selective localization and efficacy of the drug delivery system. Recent results on synthesis, structure and function, toxicity and selectivity will be presented.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2657.
Abstract 266: The interaction between MUC1 and erbB3 promotes erbB3 signaling and cell survival
Authors: Su Hsin-Yuan , Schroeder Joyce A.
Published: February 2011

MUC1 is an oncogenic glycoprotein overexpressed in more than 90% of metastatic breast cancers. The expression of MUC1 has been linked to promote cell transformation by interacting with a number of known oncogenes, including the erbB receptors. When coexpressed, MUC1 strongly promotes erbB1-dependent breast cancer in the WAP-TGFalpha transgenic mouse model and inhibits ligand-mediated ubiquitination and degradation of erbB1. ErbB1 belongs to a receptor tyrosine kinase superfamily, including erbB1/EGFR, erbB2/neu, erbB3 and erbB4, all of which have been implicated in cancer progression. ErbB3 is one of the dimerization partners for erbB1 implicated in invasive breast cancer and may be responsible for the resistance to erbB1-directed therapy. In the present study, we set out to understand the effect of interaction between MUC1 and erbB3 on erbB3 stability and signaling. We show that the expression of MUC1 inhibits the degradation of neuregulin1beta (NRG1beta)-stimulated erbB3 and prolongs NRG1beta-dependent dpERK and pAKT activation in BT20 breast cancer cell line. By cell proliferation assay, we demonstrate that MUC1 promotes NRG1beta-dependent survival signals in BT20 cells. ErbB1 is found to complex with erbB3 only in the presence of MUC1 and NRG1beta stimulation. In addition, MUC1 forms a complex with erbB1 and erbB3 only in the presence of NRG1beta stimulation. In summary, the interaction between MUC1 and erbB3 results in inhibition of ligand-induced degradation of erbB3 receptor and prolongation of erbB3 downstream signaling, especially ERK and AKT activation, which leads to cell survival. The possible mechanism is through the formation of functional erbB1/erbB3 heterodimers facilitated by MUC1 expression.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 266.
Abstract 2660: Folate conjugated PLGA silica coreshell nanoparticles for drug delivery
Authors: Sharraya Aschemeyer , Yang Jian , Sandoval Sergio , Alfaro Jesus , Kummel Andrew , Trogler William C.
Published: February 2011

Folate conjugated poly(lactic-co-glycolic acid) (PLGA) silica nanoparticles (NP) are being synthesized as drug carriers to cancer cells. The PLGA nanoparticles are synthesized by first combining PLGA and dye in acetonitrile. This mixture is then dropped into an aqueous solution containing lecithin (a lipid) and poly(ethylene glycol) (PEG) to form an emulsion. The acetonitrile is evaporated leaving the nanoparticles in a water suspension. Silicic acid is used to coat the PLGA NP through the sol-gel process assisted by poly-L-lysine to template the growth of the silica shell. This makes a more hydrophilic and easily modified surface. 3-aminopropyltriethoxysilane is used to coat the silica surface with amine groups. Then folic acid is coupled to the amine modified silica surface. The folic acid acts as a targeting agent which recognizes folate receptors on the membrane surface of cancer cells. A fluorescent dye is loaded into the PLGA core to mimic a hydrophobic drug in these initial studies. Then the ability of PLGA silica NP with folate are allowed to undergo endocytosis into the HeLa cells, and the degree of uptake is assessed by fluorescence microscopy. The results are compared to folate PLGA NP as a control. Detailed synthesis of these silica PLGA nanoparticles, their characterization, surface functionalization, and their applications will be presented.

This presentation was made possible by NIH grants:5P30CA23100; and 1U54CA132379/1U54CA132384.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2660.
Abstract 2663: Preclinical pharmacokinetic characterizations and human pharmacokinetic prediction of AMG 900, an orally available small molecule inhibitor of aurora kinases
Authors: Huang Liyue , Be Xuhai , Berry Loren , Pan Wei-Jiang , Zhao Zhiyang , Lin Min-Hwa Jasmine
Published: February 2011

Introduction: AMG 900 is a small molecule being developed as an orally administered, highly potent and selective pan-aurora kinase inhibitor. AMG 900 is currently undergoing phase 1 clinical evaluation in patients with advanced solid tumors. The objectives of the studies were to characterize single dose pharmacokinetics (PK) of AMG 900 in preclinical species and use the preclinical PK data to predict its human PK. Methods: Following a single intravenous and oral administration of AMG 900 to mice, rats, dogs, and monkeys, blood samples were collected and processed for plasma by centrifugation. AMG 900 plasma concentrations were determined by LC-MS/MS. Non-compartmental analysis of the concentration - time data was performed to calculate PK parameters of AMG 900. Human PK were predicted based on data from preclinical species using the simple allometric scaling method assuming a human body weight of 60 kg. Results: AMG 900 exhibited low (mouse, monkey and dog) to moderate (rat) clearance in the species evaluated. The volume of distribution at steady state was less than 0.5 L/kg across species. Following intravenous administration, the compound had terminal elimination half-life ranging from 0.6 to 2.4 hours. AMG 900 was well absorbed in fasted animals across species with an oral bioavailability ranging from 31% to 104%. The clearance and volume of distribution at steady state in humans were predicted to be 0.03 L/hr/kg and 0.1 L/kg, respectively, with the predicted half-life to be approximately 2.3 hours. Bioavailability after oral administration of AMG 900 was predicted to be 75%, calculated from the mean values observed in non-clinical species. Conclusion: AMG 900 exhibits good PK properties in preclinical species and it was predicted to have low clearance and good oral bioavailability in human. Available PK results from the on-going phase 1 trial are consistent with the allometric scaling predictions.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2663.
Abstract 2664: Pharmacokinetics of a novel fumagillol conjugate XMT-1107 in the rat and the dog
Authors: Yurkovetskiy Alexander , Cabral Carolina B. , Meyers Laraine L. , Fram Robert J. , Lowinger Timothy B.
Published: February 2011

XMT-1107 is a novel polymer fumagillol derivative, comprised of the small molecule XMT-1191 conjugated to a 70 kDa biodegradable, hydrophilic polyacetal, poly(1-hydroxymethylethylene hydroxymethylformal) (PHF). The conjugated drug XMT-1107 is a prodrug that improves the pharmacokinetics (PK) of the active compound XMT-1191 and demonstrates significant antitumor activity in multiple rodent xenograft models providing a compelling rationale for clinical development. We evaluated the metabolism and PK of XMT-1107 in the rat and the dog and expect that the preclinical dog toxicokinetic (TK) data provide better guidance than the rat data for the assessment of XMT-1107 safety/PK in humans.

XMT-1107 metabolism was studied in rodent, dog and human plasma as well as in liver microsomes. The PK of XMT-1107 was studied in rat and dog at a variety of doses and schedules. The extent and duration of the exposure was monitored over 120 hours post dosing. The analytical determinations of XMT-1107 and small molecule metabolites were carried out by LC/MS/MS.

XMT-1107 was metabolized in rodent, dog and human plasma producing XMT-1191 and XMT-1201 (via conjugated XMT-1201) as major and minor metabolites, respectively. Considering that XMT-1201 does not bind to or inhibit MetAP2, the molecular target of XMT-1107, conjugated and free XMT-1191 are of most interest since conjugated XMT-1191 is a prodrug and XMT-1191 is its active release product.

In both species the PK of conjugated and free XMT-1191 was approximately dose proportional with no marked gender differences. Consistent 2,000-4,000 fold differences between conjugated XMT-1191 and free XMT-1191 plasma exposure (AUC0–120) and Cmax suggest that observed pharmacological effects may result from extravascular distribution of conjugated XMT-1191 and local release of XMT-1191 rather than from systemic exposure to free XMT-1191. Conjugated XMT-1191 has a low volume of distribution, slow systemic clearance and is characterized by a t1/2 ranging from 27-35 hours in rat and 47-68 hours in dog. The 1.8-2.0-fold increase in conjugated XMT-1191 plasma t1/2 observed in dog relative to rat was accompanied by an approximately proportional increase in dose normalized exposure (AUC0–120) to conjugated XMT-1191 and conjugated XMT-1201. The rates for in vitro release of XMT-1191 and XMT-1201 from XMT-1107 in dog and human plasma were similar and at least 2 times lower than the release rates for corresponding compounds in rat plasma, suggesting that dog TK may be more predictive of human XMT-1107 PK compared to rat TK.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2664.
Abstract 2665: Impact of structural modifications on bioactivity and metabolic stability of indirubins
Authors: Eisenbrand Gerhard , Cheng Xinlai , Zeller Jochen , Merz Karl-Heinz
Published: February 2011

Indirubins are potent inhibitors of a series of protein kinases. They induce cell cycle arrest in G1/S and/or G2/M followed by apoptosis and potently inhibit proliferation of human tumor cells. However, most indirubins are extremely poorly soluble in solvents, resulting in a low bioavailability. Furthermore, they are prone to deactivating metabolic transformations. As reported previously1, incubation of 5-methylindirubin (E224) with bovine and rat liver microsomes in the presence of a NADPH-generating system resulted in the formation of two main hydroxylated metabolites, 6-hydroxy- and 6,7′-dihydroxy-5- methyl-indirubin. The antiproliferative activity of the former metabolite was decreased, the activity of the latter was abrogated nearly completely.

To improve metabolic stability and solubility, novel indirubins were synthesized: 7′-Aza-5-methylindirubin (E844), N,N-dimethylaminophenyl indirubin-5-carboxamide (E744), and indirubins carrying a hydrophilic N-methylpiperazinoethyl group attached to the indirubin core by a 5-carboxamide anchor (E748) or by a 3′-oxime ether link (E857). Compounds were in vitro incubated with liver microsomes (rat and bovine) and metabolites formed were isolated and analyzed. The main metabolites of E844 were identified to be 7′-aza-5-methyl-6-hydroxy-indirubin and 7′-aza-5-hydroxymethyl-indirubin. From incubations of E748, the 7′-hydroxy derivative was isolated as main metabolite and structurally elucidated by 1H-NMR. In contrast to E748 with an N-methylpiperazinoethyl side chain, E744 did not appear to undergo appreciable metabolic transformation. Moreover, E857 and its water soluble hydrochloride (E857a) were found not to be hydroxylated at the respective bisindole positions. Instead, the main biotransformation of E857 occured in the side chain leading to the corresponding N-methylpiperazinoethyl-N-oxide metabolite. The structure was confirmed by synthesis. E857a was found to carry a hydroxylated methylpiperazino group after incubation.

In summary, deactivating metabolic transformation of indirubins is decreased by variation of the electron density of the heterocyclic aromatic system. Furthermore, attachment of appropriate substituents at position 3′ directs metabolic transformation into the side chain of such substituents that ensure improved water solubility, bringing about increased metabolic stability of the pharmacophore.

1 AACR Annual Meeting 2007 abstr. #3957

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2665.
Abstract 2672: Characterization of Hsp90/Cdc37 interaction and their critical residues using luciferase fragment complementation imaging
Authors: Jiang Yiqun , Bernard Denzil , Yu Yanke , Zhang Tao , LI Yanyan , Fu Xueqi , Wang Shaomeng , Sun Duxin
Published: February 2011

The purpose of this study is to investigate Hsp90/Cdc37 interaction and identify residues critical for the interaction using real-time luciferase complementation imaging and computational modeling. Molecular imaging using a split Renilla luciferase fragment complementation (SRL-FC) was established to monitor real-time Hsp90/Cdc37interactions in living cells. Computational modeling and molecular dynamics simulations were used to evaluate the interaction interface of Hsp90/Cdc37 complex and critical residues in the interaction interface were identified for mutagenesis. Western Blotting and co-immunoprecipitation were used to determine protein expression and complex formation. The molecular imaging in living cells showed that Hsp90 and Cdc37 helped the complementation of N-terminus of Renilla luciferase (fused with Hsp90; N-RL-Hsp90) and C-terminus of Renilla luciferase (fused with Cdc37, Cdc37-C-RL) with 170-fold higher luciferase activity than controls without Hsp90/Cdc37. This suggests that the SRL-FC is sensitive and specific to monitor the interaction of full length human Hsp90 and Cdc37. Molecular dynamics simulations revealed that the interface was constituted by a series of residues interacting through hydrophobic or polar interactions. Mutagenesis confirmed that mutations in Hsp90 (A121N, Q133A, F134A) and mutations in Cdc37 (M164K, R167A) led to the loss of complementation of N-RL-Hsp90 and Cdc37-C-RL (5 to 10-fold lower luciferase activity compared to wild-type), indicating these residues are critical in Hsp90/Cdc37 interactions. In comparison, mutations in Hsp90 (E47A, S113A) and mutations in Cdc37 (A204E) only decreased 50% of the complementation of N-RL-Hsp90 and Cdc37-C-RL, which suggests that these residues contribute less to Hsp90/Cdc37 interaction. In contrast, mutations of Hsp90 (R46A, S50A) and mutation in Cdc37 (L165H) did not change the complementation of N-RL-Hsp90 and Cdc37-C-RL, indicating that these residues did not contribute to Hsp90/Cdc37 interaction. The data suggests that molecular imaging using split Renilla luciferase fragment complementation (SRL-FC) can be used to identify the critical residues in Hsp90/Cdc37 interaction. Although Hsp90/Cdc37 interactions are through both hydrophobic and polar interactions, mutation in a single amino acid residue, including Ala121, Gln133, Phe134 in human Hsp90 and Met164, Arg167 in human Cdc37, is sufficient to disrupt Hsp90/Cdc37 interaction.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2672.
Abstract 2675: Characterization of human thioesterase 2 and its potential for breast cancer drug discovery
Authors: Ritchie Melissa K. , Johnson Lynnette C. , Watts Laura A. , Kridel Steven J. , Lowther W. Todd
Published: February 2011

Human thioesterase II (TE2) may limit the anti-tumour potential of fatty acid synthase (FASN) inhibitors designed to target endogenous thioesterase (TE1) domain of FASN in breast cancer. Recent studies have firmly established the anti-tumour effects of TE1-targeted FASN inhibition via the drug Orlistat in prostate tumour xenografts, and current studies are revealing similar cytotoxic effects in breast cancer cell lines. Both TE1 and TE2 act on the acyl carrier protein (ACP) domain of FASN to liberate fully saturated, long-chain or medium-chain fatty acids, respectively. Therefore, TE2 may rescue fatty acid synthesis on TE1 inhibited FASN in cancer cells, thus highlighting TE2 as a potential new target for cancer therapy. Encouraged by the developments in TE1 inhibitors and by the expression of TE2 in breast cancers, we are now investigating the biochemical and structural properties of recombinant TE2 in order to define the factors that determine substrate specificity. In addition, the expression profile of endogenous TE2 in several breast cancer cell lines is under investigation. The long-term goal of this project is to determine whether TE2 is a viable target for the development of breast cancer specific anti-tumour therapies and/or whether a combined drug discovery strategy against both thioesterases must be pursued. Here we report the kinetic profiling of human TE1 and TE2 using model substrates and select β-lactone inhibitors. As well, we report immunoblot analyses of endogenous TE2 in MCF 7, SKBr 3, and MDA 231 breast cancer cell lines. Finally, we report the current progress of determining the crystal structure of recombinant TE2. Our results show lower β-lactone inhibitor potency against TE2 compared with TE1, as well as differential expression of endogenous TE2 in breast cancer cell lines. These results suggest that TE2 may need to be specifically targeted in breast cancer in order to fully realize the anti-tumour potential of FASN inhibition.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2675.
Abstract 2679: Virtual screening of small molecule inhibitors towards the tumor suppressor p53 to overcome radioresistance of nasopharyngeal carcinoma cells
Authors: Eichhorn Tolga , Efferth Thomas
Published: February 2011

The tumor suppressor p53 belongs to the most frequently mutated genes in cancer, including nasopharyngeal carcinoma (NPC). p53 is over-expressed in NPC, but the mutation rate is lower than in other tumor types. Therefore, it can be hypothesized that p53 might be involved in repair of DNA-damage after radiotherapy and causes recrudescence. Hence, the aim of the present investigation was to identify small molecule inhibitors for p53 to inhibit DNA repair after ionizing radiation of NPC.

Approximately 260.000 2D-structures from NCI database were downloaded and different tautomers and charged stages between pH 5 and 9 were calculated for each compound. A total number of 906.587 drugs in different 3D-conformations have been generated for our virtual screening approach. By means of the Glide software and three-dimensional p53 structure based on the published crystal structure 1TUP from PDB database, 25 compounds have been identified as candidates to bind to the DNA-binding domain of p53. The best evaluated ligand (consisting 26 atoms) had the assigned binding energy of −8.41 kcal mol-1 in Glide. This outstanding binding was confirmed by using AutoDock which has result in −10.57 kcal mol-1. In comparison, the binding of PRIMA-1 as experimentally validated drug showed a binding energy of −6.30 kcal mol-1 after blind docking procedure with subsequent refinement.

As a next step, the compounds identified in silico have been experimentally verified in vitro by means of Plasmon resonance spectroscopy. To prove, whether inhibition of DNA-binding of p53 by these small molecule inhibitors affect the response of the NPC cell line CNE1 towards ionizing radiation, the cytotoxicity of 0.5 – 16 Gy has been measured with and without addition of these small molecule inhibitors by XTT assays. Indeed, the addition of some of the identified candidate compounds were able to increase the cytotoxic effects of ionizing radiation.

The present investigation indicates that the combination of ionizing radiation with novel small molecule inhibitors for p53 increased the killing rate of CNE1 cells. These data may have important implications for radiochemotherapy of NPC in the future.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2679.
Abstract 2688: The expression of lung resistance protein (LRP) in patient ascites predicts platinum resistance in advanced epithelial ovarian carcinoma
Authors: McNally Lacey R. , Frederick Peter J. , Bevis Kerri S. , Sellers Jeffrey C. , Della Manna Debbie L. , Straughn J Michael , Stockard Cecil R. , Grizzle William E. , Buchsbaum Donald J.
Published: February 2011

The human lung resistance protein (LRP) is a multidrug resistance protein that has been shown to be overexpressed in numerous chemotherapy resistance models. The precise role of LRP in platinum-resistant epithelial ovarian cancer (EOC) has yet to be fully elucidated. In this study, we sought to determine LRP expression in the tumor cells of ovarian cancer patient ascites of chemotherapy-naïve patients with advanced EOC.

After IRB approval was obtained, patient ascites was collected and evaluated for platinum sensitivity, and LRP expression using western blot and immunohistochemistry (IHC). Both patient ascites and primary tumor were treated with 50 uM carboplatin for 48h and cell viability was analyzed. LRP, activated Caspase 3, and tunnel were analyzed using IHC on samples treated with 50uM carboplatin and untreated.

A total of 27 patients with advanced-stage EOC undergoing primary cytoreductive surgery at the University of Alabama at Birmingham were consented for the study. Ten patient ascites samples were deemed adequate for analysis. Of these, 3/10 (30%) had increased LRP levels in ascites samples demonstrated by strong IHC staining with capping and confirmed by western blot. These patient samples were platinum resistant as verified by cytotoxicity analysis. Two ascites specimens (20%) lacked LRP expression by IHC and western blot and demonstrated platinum sensitivity on cytotoxicity. Five ascites specimens (50%) displayed intermediate LRP staining and platinum cytotoxicity. Tumor cells in ascites treated with carboplatin had an inverse correlation of LRP staining and activated Caspase 3.

There is a strong correlation between LRP expression in the ascites of patients with advanced EOC and platinum resistance in this ex vivo model. This protein may therefore predict poor prognosis disease unlikely to respond to adjuvant platinum therapy. Specifically targeting the LRP in a clinical model may reverse carboplatin resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2688.
Abstract 2694: DNA copy number aberrant profiles predict complete pathologic tumor response to preoperative chemoradiation therapy in locally advanced rectal cancer
Authors: Chen Zhenbin , liu Zheng , Wu Xiwei , Li Wenyan , Garcia-Aguilar Julio
Published: February 2011

Purpose: The treatment of locally advanced rectal cancer includes chemoradiation (CRT) followed by surgical resection. The response of rectal cancers to the CRT is variable. The finding that up to 25% of tumor seem to be totally eradicated by the CRT has raised the question as to whether surgery can be avoided in these patients. Findings predictors or response or resistance to CRT could potentially change the treatment paradigm of rectal cancer patients. In this study we explored DNA copy number alterations as predictors of rectal cancer response to preoperative CRT.

Patients and Methods: High-density oligonucleotide-based comparative genomic hybridization (human 244k aCGH kit, Agilent Cor.) was employed to identify the DNA copy number alterations in 89 pretreatment tumor biopsy specimens and paired normal surgical specimens collected from stage II and III rectal cancer patients treated in a prospective multi-institutional study. Data analysis was performed using Nexus Copy Number and Ingenuity Pathway Analysis. A pathologic complete response (pCR), defined as absence of cancer cells in the surgical specimen, was used as clinical end-point.

Results: A total of 25 (28%) patients had a pCR. The pCR rate was higher among tumors with low fractional genomic alterations (FGA, ≤21%) (12/26 or 46.1%) compared to tumors with high FGA (>21%) (13/63 or 20.6%) (p<0.02). Gain or losses of individual chromosome segments containing individual candidate genes and miRNAs in tumors with or without pCR are presented in table 1.Chrom. LocationCandidate GeneChangepCRNon- pCRp-valuechr18q21.2SMAD4loss52%82.8%0.0059chr.8p12EIF4EBP1loss8%35.9%0.0085chr.17q12ERBB2gain4%29.7%0.0098chr.16p12.1PRKCBgain4%29.7%0.0098chr.7p15.2hsa-mir-148again32%58.7%0.0352

Conclusion: This study shows that DNA copy number aberrations, measured as a FGA and individual chromosome regions gain and loses, may be predictors of rectal cancer resistance to CRT. This information could be used to select patients that may not benefit from a non-surgical treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2694.