bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 568: Biomarkers of phenethyl isothiocyanate-mediated mammary cancer prevention in MMTV-neu mouse model
Authors: Singh Shivendra V. , Kim Su-Hyeong , Sehrawat Anuradha , Arlotti Julie A. , Sakao Kozue , Lee Joomin , Chandra-Kuntal Kumar , Hahm Eun-Ryeong
Published: August 2012

Biomarker(s) predictive of efficacy is necessary for clinical development of promising cancer chemopreventive agents because cancer incidence is too rigorous of an end point for malignancies with long latency such as breast cancer. The present study was undertaken to identify biomarker(s) associated with phenethyl isothiocyanate (PEITC)-mediated mammary cancer prevention in MMTV-neu transgenic mouse model. The PEITC is a promising cancer chemopreventive constituent of cruciferous vegetables (e.g., watercress). Two-dimensional gel electrophoresis-mass spectrometry of tumor specimens from control and PEITC-fed mice (n= 3) revealed alterations in expression of several proteins, including hexokinase-1, isoform CRA_f (1.36-fold increase by PEITC administration), L-lactate dehydrogenase A chain isoform 1 (1.57-fold increase by PEITC administration), pyruvate kinase isozymes M1/M2 (1.33-fold decrease by PEITC administration), and mitochondrial ATP synthase, H+ transporting F1 complex beta subunit (1.38-fold decrease by PEITC administration). Interestingly, the PEITC-induced apoptotic cell death in cultured cancer cells is associated with inhibition of oxidative phosphorylation leading to production of reactive oxygen species. Down-regulation of mitochondrial ATP synthase protein in tumors of PEITC-fed mice was confirmed by immunohistochemistry. Expression of mitochondrial ATP synthase was reduced by about 66% in the tumors from PEITC-fed mice in comparison with control (P= 0.05 by two-sided Student's t-test, n= 6-7). In addition, plasma level of transthyretin was significantly higher in the PEITC treatment group compared with control (P= 0.04 by two-sided Student's t-test, n= 5). In conclusion, the present study not only underscores the power of proteomics in cancer chemoprevention research but also suggests that mitochondrial ATP synthase, and possibly hexokinase-1, pyruvate kinase isozymes M1/M2, and/or L-lactate dehydrogenase A chain isoform 1, may be useful biomarkers to assess the biological activity of PEITC in future clinical trials. This study was supported in part by the US PHS grants CA101753 and CA129347, awarded by the National Cancer Institute.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 568. doi:1538-7445.AM2012-568
Abstract 5681: A high throughput soft agar assay on a panel of 60 tumor cell lines to study compounds for potential anti-oncogenic properties
Authors: Weber Holger , Mueller Melanie , Ehlert Jan E.
Published: August 2012

In the course of drug development, analysis of cellular efficacy represents a critical stage before drugs proceed into in vivo studies. For anti-cancer drugs, one method of choice is to assess the drug's impact on tumor cell proliferation. Usually proliferation is analysed in 2D format, analysing cell growth on a flat surface. However, accumulating data suggest that cells behave in a more physiological manner when growing in a 3D matrix. In fact, the gold standard for analysing the transformed status of cells is growth in soft agar, a semi-solid medium in which epithelial cells grow in 3D due to their transformation-related anchorage-independent status. In order to allow a more physiological cellular drug screening for proliferation as well as for transformation, we have now established soft agar assays in 96 well format for 60 tumor cell lines derived from solid tumors. Our data show the multitude of outcomes that may be expected from such a comprehensive study, e.g. we present IC50 analyses indicating that the same compound can have seemingly contradictory, i.e. stimulatory as well as inhibitory activity on soft agar growth, depending on concentration and tested cell line. We propose screening of compounds for impact on cellular soft agar growth as a mandatory prerequisite before testing a drug in vivo.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5681. doi:1538-7445.AM2012-5681
Abstract 5683: Design and characterization of novel targeted nanoparticle delivery systems for cancer chemotherapy
Authors: Yin Juanjuan , Sneed Kevin Bernard , Zhou Shufeng
Published: August 2012

The success of cancer chemotherapy was considerably hindered by tumor resistance and drug toxicity. A possibly efficient approach to overcoming drug resistance and serious toxicities is the application of targeted nanoparticles linked to or encapsulating cytotoxic drugs. In this study, novel self-assembly targeting supramolecular nanodrug complex was synthesized using αv-intergrin targeting peptidyl cyclodextrins (CyDs) and classic chemotherapeutic drugs used in the therapy of tumor. The targeting supramolecular drug complex were obtained through host-guest interaction between the tripeptide RGD with sequence Arg-Gly-Asp or cyclotripeptide cRGDyk with sequence c (Arg-Gly-Asp-DTyr-Lys) grafting β-cyclodextrin (or γ-cyclodextrin) and a cytotoxic prodrug; the supramolecular drug inclusion are in specific and efficient binding to integrin-expressing tumor cells and would release the chemotherapeutics in a prolonged period. The guest molecule was generated by the reaction of adamantyl chloride and doxorubicin hydrochloride in which the adamantly group acts as a perfect candidate for the host-guest interaction with CyDs. The host moiety was gained through the reaction of mono-6-deoxy-6-(p-tolylsulfonyl)-β-cyclodextrin and the N-terminal of the oligopeptides through nuclephilic reaction. The promising nanodrug complex is expected to offer attractive pharmacokinetic and pharmacodynamic properties for cancer treatment and is undergoing preclinical evaluation using cancer cell lines and nude mouse models.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5683. doi:1538-7445.AM2012-5683
Abstract 5686: Engineering multifunctional nanoparticles to selectively target multiple myeloma cells and overcome cell adhesion-mediated drug resistance
Authors: Kiziltepe Tanyel , Ashley Jonathan D. , Stefanick Jared F. , Alves Nathan J. , Handlogten Micheal W. , Qi Yu Meng , Suckow Mark , Navari Rudolph , Bilgicer Basar
Published: August 2012

In the continuing search for effective treatments for cancer, here we report the rational engineering of a novel multifunctional nanoparticle that combines traditional chemotherapy with cell targeting and anti-cellular-adhesion functionalities to selectively target multiple myeloma (MM) cells and overcome cell adhesion-mediated drug resistance (CAM-DR). Anti-cellular-adhesion evolves as a promising target in oncology. VLA-4-mediated adhesion to the bone marrow extracellular matrix and stromal cells confers MM cells with CAM-DR. In our design, we used micellar nanoparticles as dynamic self-assembling scaffolds to present VLA-4-antagonist peptides and doxorubicin conjugates simultaneously to selectively target MM cells and to overcome CAM-DR. Doxorubicin was conjugated to the nanoparticles through an pH-sensitive hydrazone bond to prevent premature release and thus non-specific toxicity. Peptides were conjugated via a multifaceted synthetic procedure for generating precisely controlled number of targeting functionalities per nanoparticle. The nanoparticles, which exhibited a size of ∼20nm, were efficiently internalized by MM cells with an optimal peptide valency of 20 per micelle, and induced cytotoxicity to MM cells. Mechanistic studies revealed that nanoparticles induced DNA double strand breaks as evidenced by H2AX phosphorylation, and triggered apoptosis, which was associated with PARP and caspase-8 cleavage. Importantly, multifunctional nanoparticles were more efficacious than doxorubicin in the presence of fibronectin (IC50=0.15±0.04 μM and 0.42±0.09 μM, respectively), and overcame CAM-DR induced by adherence of MM cells to fibronectin. Finally, in a MM xenograft model, nanoparticles preferentially homed to MM tumors, with a ∼10 fold more drug accumulation when compared to doxorubicin, and demonstrated dramatic tumor growth inhibition with much reduced overall systemic toxicity. Taken together, we demonstrate the disease-driven engineering of a nanoparticle-based drug delivery system, enabling the model of an integrative approach in the treatment of MM.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5686. doi:1538-7445.AM2012-5686
Abstract 5690: Validating sigma-2 receptor ligand as a novel tumor-targeted drug delivery agent for treating ovarian cancer
Authors: Zeng Chenbo , Vangveravong Suwanna , Rothfuss Justin M. , Xu Jinbin , Mach Robert H.
Published: August 2012

The sigma-2 receptor is overexpressed in various human tumors. Sigma-2 receptor selective radiotracers have been shown to target various solid tumors in rodents and in human patients using positron emission tomography. Sigma-2 receptor ligands can be internalized into tumor cells by the endocytotic pathway. Therefore, sigma-2 receptor ligands are excellent candidates as tumor-targeted delivery agents when covalently attached to drugs. Smac is a protein released from mitochondria into the cytosol in response to apoptotic stimuli. Small-molecule Smac mimetic compounds (SMC) have been developed by several laboratories as anticancer drugs. In this study we validate sigma-2 ligand as a tumor-targeting drug delivery agent for treating ovarian cancer. We have synthesized sigma-2 ligand-conjugated SMC (SSMC), SW III-123. Our data show that SW III-123 has adequate sigma-2 receptor binding affinities (Kiα2 =190 nM and Kiα1 =2046 nM). SW III-123 exhibits potent antitumor activities with EC50 values at 4.0 μM, 2.3 μM and 2.4 μM in human ovarian cancer cell lines SKOV-3, CaOV-3, and BG-1, respectively. In contrast, unconjugated SMC, SW IV-52s, shows little cytotoxicity in these cell lines (EC50 > 200 μM). These results suggest that the sigma-2 ligand has successfully delivered SMC into ovarian cancer cells. Western blot results show that SW III-123 degrades inhibitor of apoptosis proteins (IAPs), XIAP and cIAP-1, in SKOV-3 cells, possibly by interacting with the baculovirus IAP repeat (BIR) domains of IAPs. SW III-123 cleaves caspase-3, 8, and 9 dose-dependently in SKOV-3 cells, indicating that SW III-123 kills ovarian cancer cells by activating both intrinsic and extrinsic apoptotic pathways. In conclusion, sigma-2 ligand is a promising tumor-targeting drug delivery agent. SSMC will likely offer a novel class of therapeutic drugs for treating ovarian cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5690. doi:1538-7445.AM2012-5690
Abstract 5698: Concurrent delivery of paclitaxel and 17-AAG via micellar nanocarriers
Authors: Katragadda Usha , Fan Wei , Tan Chalet
Published: August 2012

Combination therapy of paclitaxel and 17-allylamino-17-demethoxygeldanamycin (17-AAG) had previously been tested in patients with advanced solid malignancies. Owing to the very low aqueous solubility of both drugs, large volumes of organic solvents were employed in the intravenous formulations, which contributed to serious toxicities in cancer patients and consequently restricted the optimal use of these drugs in the clinical setting. The aim of the present study was to develop micellar nanocarriers for concomitant delivery of paclitaxel and 17-AAG without the inclusion of any organic solvent. At clinically relevant concentrations, paclitaxel and 17-AAG were simultaneously loaded into polyethylene glycol-distearoylphosphatidylethanolamine (PEG-DSPE) micelles by a dry film method. The physicochemical and biological characteristics of the dual drug-loaded micelles were evaluated in vitro and in vivo. The simultaneous incorporation of paclitaxel and 17-AAG into PEG-DSPE micelles was confirmed by 1H NMR analysis. The drug-loaded micelles had an average diameter of 11 nm with a surface charge at −22 mV. In the presence of 90% serum, the release half-lives of paclitaxel and 17-AAG from PEG-DSPE micelles were 7.1 h and 4.8 h, respectively. Paclitaxel/17-AAG-loaded micelles were as effective in blocking the proliferation of human ovarian cancer SKOV-3 cells as the combined free drugs. When administered intravenously to nude mice bearing SKOV-3 tumor xenografts, paclitaxel/17-AAG-loaded PEG-DSPE micelles resulted in significantly elevated drug concentrations in the blood circulation and tumor tissues, compared to the free drug counterparts. These results suggest that paclitaxel/17-AAG-loaded micelles preferentially accumulate in the tumor tissue via the enhanced permeability and retention (EPR) effect. PEG-DSPE micellar nanocarriers may provide a novel and advantageous delivery approach for paclitaxel/17-AAG combination therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5698. doi:1538-7445.AM2012-5698
Abstract 57: Adipocyte oxidative stress promotes epithelial-mesenchymal transition (EMT) related gene expression and estrogen receptor (ER) negative phenotype in breast cancer cells
Authors: Yao-Borengasser Aiwei , Monzavi-Karbassi Behjatolah , Hedges Rebecca A. , Kieber-Emmons Thomas , Kadlubar Susan A.
Published: August 2012

Epidemiological studies have linked obesity with basal-like breast cancer risk in both premenopausal and postmenopausal women, suggesting that obesity may affect tumor phenotype by skewing the microenvironment toward support of more aggressive tumor cell phenotypes (typically ER/PR−, HER-2−). In order to study the interactions between adipocytes and breast tumor cells, we developed an adipocyte-breast cancer cell co-culture system. The adipocytes SGBS (Simpson-Golabi-Behmel Syndrome) and human ER positive breast cancer MCF7 cells were co-cultured for 24 hours. Following co-culture, the cells from the inserts (MCF7 cells) and wells (SGBS cells) were collected separately and total RNA was then isolated. The mRNA levels of the NADPH oxidase subunit NOX4 and hypoxia-inducible factor 1α (HIF1α) were determined by RT-PCR and normalized to 18S RNA levels. When SGBS cells were co-cultured with MCF7 cells, SGBS NOX4 and HIF1α mRNA levels increased more than 10 fold and 3 fold, respectively, while there were no changes in NOX4 and HIF1α expression detected in co-cultured MCF7 cells. We also compared several epithelial-mesenchymal transition (EMT) process-related gene expression levels. Expression in MCF7 cells of the EMT-inducing transcription factors FOXC2 and Twist1 were increased more than 8 fold and 5 fold respectively, after co-culture with SGBS. E-cadherin mRNA level was decreased 2 fold, while N-cadherin mRNA level was increased more than 6 fold in co-cultured MCF7. We also found that mRNA levels of ER-α were significantly (p<0.05) repressed in MCF7 cells co-cultured with SGBS cells. To explore the mechanism of the effect of adipocyte co-culture on ER expression in breast cancer cells, SGBS cells were transfected with 30nM of siHIF1α for 48 hours before co-culture with MCF7 cells. ER gene expression level did not change in MCF7 cells co-cultured with SGBS cells that had been transfected with siHIF1α. In summary, we have shown that adipocytes and breast tumor cells interact with each other: MCF7 cells increased hypoxia and oxidative stress in SGBS cells, while SGBS increased the expression of EMT-inducing factor genes in MCF7 cells, as well as repressing ER expression. This repression was controlled, at least in part, by HIF1α. These results suggest that hypoxia and oxidative stress from adipocytes can modify ER gene expression and promote EMT processes in breast cancer cells, supporting an important role of obesity in aggressive breast cancer development.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 57. doi:1538-7445.AM2012-57
Abstract 5707: The EPR effects of Elastin-like polypeptide of differnt molecular sizes in animal tumor models
Authors: Ryu Jung Su , Raucher Drazen
Published: August 2012

Elastin-like polypeptide (ELP) biopolymers are thermally responsive macromolecular carriers that are soluble in aqueous solution at physiological temperature (37° C), but aggregate when the temperature is raised above its transition temperature (Tt, 42° C). We have developed this carrier system for the delivery of anticancer therapeutic peptides and small molecule drugs, which has the potential to be targeted to the tumor site by applying local hyperthermia. Molecular size is one of the key determinants of trans-vascular transport of therapeutic agents in tumors as it affects not only the retention in the tumor but also the transition temperature of the macromolecule. As an effort to develop the optimal ELP carrier system, three Bac-ELP macromolecular drug carriers with a clinically relevant range of molecular weights (35, 60 and 120kD) were designed. The three sizes of ELP were initially synthesized and modified by the addition of the cell-penetrating peptide Bac on the N-terminus. In order to measure enhanced permeability and retention (EPR) effects of the three sizes of conjugates, we compared the distribution of conjugates in tumors of animals and their pharmacokinetics in the three fluorescently-labeled Bac-ELP constructs. First, we confirmed that the transition temperature of all 3 constructs fall between the ideal concentration ranges of 10 - 40 μM. In distribution studies with tumor-bearing mice, three peptides showed increased uptake in tumors during the initial 8 hours after local hyperthermia was applied, but the elimination patterns from the tumors differed according to size over a 3 day period. Local hyperthermia was found to produce a more prolonged retention of ELP conjugates in tumors except in the 35 kD Bac-ELP (Bac-E80), which was the smallest construct tested. In addition, the pharmacokinetic analysis showed that the two larger polypeptides have long half-lives and increased AUC in comparison with Bac-E80. From all these results, we suggest that the larger ELP conjugates (60 and 120kD) have advantages over 35kD of Bac-E80 in terms of enhanced permeability and retention effects when combined with local hyperthermia.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5707. doi:1538-7445.AM2012-5707
Abstract 5711: Applying new light to the detection and treatment of brain cancers using targeted photodynamic therapy
Authors: Meyers Joseph D. , Broome Ann-Marie , Cheng Yu , Agnes Richard S. , Wang Xinning , Kenney Malcolm E. , Burda Clemens , Basilion James P.
Published: August 2012

Currently, an estimated 11.4 million people in the US have been affected by cancer and this number is expected to double by 2020 as indicated by the NIH NCI in 2006. Each year approximately 20% of these people are expected to die of cancer, with brain cancers among the most deadly. Brain cancer patients have a median life expectancy of only 6-10 months after diagnosis, and those with recurring brain cancer survive less than 20 weeks after any therapeutic regime. Consequently, there is a critical need to develop and improve the detection, diagnosis, and treatment of brain cancers, including gliomas. Theranostic drugs have the potential to do all of these and are becoming lifesaving alternatives. However, the current standard of care suffers from lack of specificity and systemic toxicity, often requiring invasive surgical procedures. These are significant obstacles when dealing with minimizing offsite damage to the healthy brain while maximizing treatment efficacy in the tumor. Our study presents a novel drug delivery platform using targeted-gold nanoparticles (Au NP) to deliver a therapeutic photodynamic therapy (PDT) drug, phthalocyanine 4 (Pc 4), across the blood-brain tumor barrier (BBTB), which allows both detection and treatment of gliomas within mere hours. Targeting Pc 4 to cancer-specific biomarkers concentrates the drug specifically at the brain tumor, significantly reducing collateral damage to healthy brain tissue. Once Pc 4 is delivered, it offers selectivity based on its defined light activation. Our targeted delivery vehicle possesses several advantages over systemic drug delivery: greater control over bioavailability of the drug, controlled release of Pc 4 directly to the site, lower concentration of drug required for PDT effect, and avoidance of systemic drug exposure. The drug delivery mechanism of targeted-Au NP Pc 4 was investigated utilizing in vivo and in vitro fluorescence imaging, immunohistochemistry, elemental analysis, biodistribution studies, and therapeutic efficacy. We are able to target cancer biomarkers specifically, deliver hydrophobic drugs across the BBTB, increase drug accumulation into the tumor, alter drug localization, and enhance PDT killing affect. As a result, this study presents a unique application of PDT to the treatment of brain tumors using photosensitizing drugs like Pc 4.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5711. doi:1538-7445.AM2012-5711
Abstract 5715: Modulation of Radiation Response after TGFβ signaling Blockade in Non-small Cell Lung Cancer (NSCLC) Cell Carcinomas
Authors: Du Shisuo , Bouquet Fanny , Pellicciotta Ilenia , Parry Renate , Barcellos-Hoff Mary Helen
Published: August 2012

Lung cancer remains one of the most prevalent and deadliest malignancies worldwide. Radiotherapy (RT) is a major therapeutic modality for inoperable non-small cell lung cancer (NSCLC). There is substantial evidence that ionizing radiation triggers activation of TGFβ especially in lung, breast and liver tumor. TGFβ inhibition prior to IR inhibits the DNA damage response in epithelial cells via blockade of ATM kinase activity (Cancer Res 62:5627, 2002; Cancer Res 66:10861, 2006) and sensitizes radiation responses in breast cancer cell lines and tumors (Clin Cancer Res 2011;17:6754-6765.). The current studies test whether TGFβ blockade prior to irradiation modulates radiation response of NSCLC cell lines, NCI-H1299, NCI-H292, H460 and Lewis Lung Cancer (LLC), assessed in vitro and in vivo. All NSCLC cell lines responded to TGFβ by phosphorylation of Smad2, which was blocked by LY364947, a small molecule TGFβ type 1 receptor inhibitor. NCI-H1299 and LLC were insensitive to TGFβ growth inhibition in vitro. LY364947 increased radiosensitivity in NCI-H1299 and H460 in clonogenic assays. Consistent with increased clonogenic cell death, TGFβ inhibition also compromised radiation-induced phosphorylation of H2AX and ATM in NCI-H1299. Treatment of cultured LLC cells with either small molecule TGFβ type 1 receptor inhibitor or TGFβ neutralizing antibody, 1D11, significantly increased LLC radiosensitivity as measured by clonogenic assay. Furthermore, C57BL mice bearing subcutaneous LLC tumors treated before and after RT with 1D11 or 13C4 isotype control antibody (20 mg/kg i.p.) resulted in greater tumor growth delay compared to RT and control antibody. Together, these data indicate that TGFβ inhibition prior to radiation attenuates DNA damage responses, enhances clonogenic cell killing, and promotes tumor growth delay. Given the recognized role of radiation-induced TGFβ in lung fibrosis, the therapeutic index for RT could be significantly increased if circumstances are defined in which TGFβ inhibition during RT both enhances lung cancer radiosensitivity and protects normal lung.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5715. doi:1538-7445.AM2012-5715
Abstract 5727: Competitive inhibition of mTOR results in tumor specific radiosensitization
Authors: Hayman Thomas J. , Bae Heekyong , Camphausen Kevin , Tofilon Philip J.
Published: August 2012

Translational control of gene expression has been implicated as a component of the cellular response to ionizing radiation (IR). The mammalian target of rapamycin (mTOR) is a critical kinase in the regulation of translation. mTOR exists in two distinct complexes: mTORC1 and mTORC2. mTORC1 regulates 4E-BP1 and p70-s6k, whereas mTORC2 regulates several AGC kinases including AKT. Most studies of mTOR have focused on the use of the allosteric inhibitor rapamycin and its analogs, which incompletely inhibit mTORC1 and do not inhibit mTORC2. In contrast, newly developed competitive mTOR inhibitors (e.g. PP242) inhibit mTORC1 output more completely and inhibit mTORC2. In the study described here, we compared the effects of rapamycin and PP242 on cellular radiosensitivity using a clonogenic assay. In two tumor cell lines originating from different histologies, U251 and MDA-MB-231, PP242 treatment 1h before irradiation increased radiosensitivity with DEFs (dose enhancement factors at 0.1 surviving fraction) of 1.52 and 1.34 respectively, whereas rapamycin had no effect. However, PP242 had no effect on the radiosensitivity of the normal human fibroblast cell line, MRC9. PP242 treatment of U251 cells resulted in a dose-dependent increase in radiosensitivity. Furthermore, addition of PP242 immediately, 1, or 6h after IR resulted in increased radiosensitivity with DEFs of 1.60, 1.50, and 1.26, respectively. To investigate the mechanism of this radiosensitization U251 cells were treated with PP242, irradiated (2Gy) and stained for γH2AX, a marker of DNA double strand breaks (DSBs). PP242 exposure significantly delayed the dispersal of radiation-induced γH2AX foci, consistent with an inhibition of DSB repair. Under conditions of clonogenic survival, exposure of U251 or MDA-MB-231 cells to 2Gy resulted in no detectable increase in mTOR output. PP242 treatment of both tumor lines resulted in complete inhibition of mTORC1/2 output whereas rapamycin only partially inhibited mTORC1 and did not inhibit mTORC2. m7-GTP batch chromatography showed PP242 induced a decrease in cap-bound eIF4G and an increase in cap-bound 4E-BP1, while rapamycin slightly increased 4E-BP1 binding and had no effect on eIF4G binding. Consistent with the effects on cap-complex formation, PP242 treatment caused a considerably greater decrease in polysome abundance than rapamycin. These results suggest that competitive inhibitors of mTOR, in contrast to rapalogs, induce tumor selective radiosensitization. Moreover, the mechanism appears to involve the inhibition of DSB repair and the suppression of translation.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5727. doi:1538-7445.AM2012-5727
Abstract 573: Deguelin inhibits the expression of estrogen receptor alpha in human breast cancer cells
Authors: Alimirah Fatouma , Mehta Rajeshwari R. , Peng Xinjian , Mehta Rajendra G.
Published: August 2012

The estrogen receptor alpha (ERα), a nuclear receptor and transcription factor governs the action of estrogen. This hormone is the major contributor to normal breast development and breast carcinogenesis. Thus, antiestrogens are widely utilized to treat and circumvent the progression of hormone receptor positive breast cancer. However, resistance to these agents develops after sustained use and major risk factors such as enhanced susceptibility to endometrial cancer have been associated with this type of treatment. In an effort to develop natural therapeutic compounds against ERα positive breast cancer, the effect of deguelin, a rotenoid isolated from an African plant; Mundulea sericea on ERα positive human breast cancer cells was investigated. Here we report that deguelin treatment downregulated the expression of ERα protein in a dose dependent manner in MCF-7 and T47D human breast cancer cell lines as determined by immunoblotting. Quantitative RT-PCR analysis revealed that the mRNA expression of ERα target genes Cathepsin D (CTSD), Trefoil factor 1 (TFF1) and the Progesterone receptor (PGR) was also downregulated by 50% in the presence of deguelin in MCF-7 cells. Furthermore, deguelin treatment significantly inhibited the proliferation of these two cell lines. Importantly, estrogen mediated stimulation of cell growth was reduced by 30% in MCF-7 cells after deguelin treatment. Together these findings suggest that deguelin suppresses ERα signaling, paving the way for the development of a novel natural therapeutic agent against endocrine receptor positive breast cancer. Future studies are aimed at deciphering the molecular mechanisms by which deguelin adversely affects ERα function. (This work was supported by NCI CA140321).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 573. doi:1538-7445.AM2012-573
Abstract 5742: Up-regulation of mitochondrial chaperone TRAP1 in cancer precursors associated with chronic inflammation
Authors: Chen Ru , Pan Sheng , Bronner Mary , Lai Keith , Crispin David A. , Lai Lisa A. , Brentnall Teresa A.
Published: August 2012

Chronic ulcerative colitis (UC) is an inflammatory bowel disease that predisposes to colorectal cancer. In chronic UC patients, the colon epithelium undergoes repeated cycles of inflammation and tissue repair, resulting in oxidative stress and accumulation of reactive oxidative species (ROS). Excessive ROS can cause oxidative stress, which may subsequently lead to damage in DNA, proteins and lipids. Using proteomics analysis of colonic mucosa from UC patients with neoplasia, we identified TNF receptor-associated protein 1(TRAP1) in the UC cancer precursors. TRAP1 is a mitochondrial chaperone which protects against oxidative stress and apoptosis. We further investigated TRAP1 in the progression of UC-associated colorectal cancer using immunohistochemistry and tissue microarray. Quantification of protein oxidation in the colonic epithelia revealed that oxidative stress was present in the colonic mucosa in both UC patients with dysplasia/cancer (progressors) and UC patients without dysplasia/cancer (non-progressors). However, TRAP1 was only up-regulated in UC progressors, but not in the non-progressors. Moreover, up-regulation of TRAP1 preceded the histological changes: it was present in both the dysplastic and non-dysplastic tissue of the UC progressors. We then investigated the cellular proteome changes underlying oxidative stress, and found that up-regulation of TRAP1 could be induced by oxidative stress. These results suggest that UC cancer arises in the setting of oxidative stress. Such oxidative stress subsequently induces the cytoprotective protein TRAP1. TRAP1 in turn appears to promote cancer progression by preventing the oxidative-damaged epithelial cells from undergoing apoptosis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5742. doi:1538-7445.AM2012-5742
Abstract 5752: Expression and biological significance of adiponectin receptors in papillary thyroid carcinoma
Authors: Cheng Shih-Ping , Liu Chien-Liang , Hsu Yi-Chiung , Chang Yuan-Ching , Huang Shih-Yuan , Lee Jie-Jen , Chen Yu-Jen
Published: August 2012

Obesity is associated with a higher incidence of thyroid cancer. Adiponectin is one of the most abundant adipokines with pleiotropic roles in metabolism and in the development and progression of cancer. This study aimed to investigate the possible association between the expression of adiponectin receptors (AdipoR1 and AdipoR2) and clinicopathological variables in papillary thyroid cancer. We found that levels of AdipoR1 and AdipoR2 were commonly increased in thyroid cancer compared with adjacent normal thyroid tissues. Thyroid cancer cells expressed AdipoR1 and AdipoR2, which were attenuated by histone deacetylase inhibitor trichostatin A. We determined the expression of AdipoR1 and AdipoR2 by immunohistochemical staining in primary tumor samples and metastatic lymph nodes. AdipoR1 was expressed in 27% of primary tumors and AdipoR2 in 47%. AdipoR1 expression correlated with AdipoR2 expression in primary tumors and in metastatic lymph nodes. Tumor AdipoR1 expression was associated with larger tumor size, whereas negative AdipoR2 expression was significantly associated with extrathyroidal invasion and multicentricity. Patients in the high AMES risk group had negative tumor expression of AdipoR1 and AdipoR2. Collectively, altered expression of adiponectin receptors in thyroid cancer supports a potential role in the pathogenesis of thyroid cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5752. doi:1538-7445.AM2012-5752
Abstract 583: Physiological concentrations of genistein reduced ER-α promoter methylation and increased ER-α expression in prostate cancer cells
Authors: Mahmoud Abeer M. , Yang Wancai , Al-Alem Umaima , Bosland Maarten C.
Published: August 2012

Prostate cancer is the most common malignancy and the second leading cause of cancer death among men in the United States. The lower incidence and mortality rates of prostate cancer in Asian population were correlated to the high dietary consumption of isoflavone-rich soy. One of the most abundant and potent isoflavones in soy is genistein which has an estradiol like structure and high affinity to estrogen receptor-α (ER-α). It has been suggested that genistein exerts its anti-cancer effects through binding to ER-α, the later has anti-proliferative and pro-apoptotic effects in prostate cancer. ER-α is mainly expressed in prostate epithelial cells and is downregulated in localized prostate cancer with increasing grade from Prostatic Intraepithelial Neoplasia (PIN) through low to high Gleason grade. This expression pattern supports the notion of a tumor suppressor role of ER-α. Therefore, ER-α agonists may be potential chemopreventive and therapeutic agents for prostate cancer. One of the mechanisms by which ER-α is suppressed in prostate cancer is promoter methylation, the extent of which correlates with the ER-α expression level which in turn may be linked to the degree of aggressiveness of prostate cancer. We examined the effects of physiological range of genistein concentrations (0.5, 1, and 10µM) on ER-α promoter methylation and ER-α expression in LNCaP, LAPC-4, and PC-3 prostate cancer cells that exhibit various basal levels of ER-α expression. We demonstrated for the first time that genistein caused a significant dose-dependent reduction in ER-α promoter methylation in LNCaP and LAPC-4 cells, using methylation specific PCR. There was a corresponding dose-related increase in ER-α mRNA and protein levels in these two cell lines assayed by quantitative RT-PCR and immunoblotting, respectively. However, ER-α expression levels and ER-α promoter methylation were not changed in PC-3 cells, which could be attributed to the low basal level of ER-α promoter methylation and the high basal level of ER-α expression in this cell line. These findings suggest that physiological concentrations of genistein is capable of reactivating tumor suppressor pathways by reversing ER-α promoter methylation with a subsequent restoration of the level of ER-α expression in prostate cancer cells that have higher basal levels of methylation. (Supported in part by Grant No. CA116195)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 583. doi:1538-7445.AM2012-583
Abstract 591: Licochalcone E inhibits solid tumor growth and lung metastasis of 4T1 murine mammary carcinoma cells in the BALB/c mouse orthotopic model
Authors: Park So Young , Kwon SooJin , Jeon Jae Ho , Jun Jong Gab , Park Jung Han Yoon
Published: August 2012

Licochalcone E a phenolic constituent of licorice that is reported to exert excellent anti-cancer effects. In the present study, to investigate the effect of licochalcone E oral administration on the solid tumor growth and metastasis of breast cancer cells, 4T1 cells were injected into the inguinal mammary fat pads of syngeneic female BALB/c mice. One week after the injection the mice were subjected to oral gavage for 25 days with licochalcone E (0, 7, or 14 mg/kg body weight/day). Licochalcone E treatment induced a significant reduction in solid tumor growth, which was accompanied by 1) reduced Ki67 (prototypic cell cycle related nuclear antigen), cyclin-dependent kinase (CDK)2, CDK4, cyclin A, and cyclin D1 and 2) increased numbers of TUNEL-positive apoptotic cells with increased Bax and cleaved caspase-3 expression but reduced Bcl-2 expression in tumor tissues. Licochalcone E also reduced the expression of hypoxia inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), VEGF-R2, CD31 (platelet endothelial cell adhesion molecule-1), VEGF-C and LYVE-1 (lymphatic vessel endothelial receptor-) in tumor tissues. In addition to tumor growth, oral licochalcone E administration markedly reduced the number of pulmonary tumor nodules. In lung tissues, licochalcone E induced a significant reduction in the levels of cytokines and angiogenesis-related proteins including DPPIV (CD26), endoglin (CD105), MMP-9, C5a, interleukin (IL)-1ra, IL-16, MIG (CXCL9). In vitro culture studies showed that licochalcone E dose-dependently inhibited the migration of MDA-MB-231 human breast cancer cells at concentrations of 0-20 μmol/L without significant changes in cell viability. Licochalcone E significantly reduced secretion of matrix metalloproteinase-9, urokinase-type plasminogen activator and VEGF in concentration-dependent manners in MDA-MB-231 cells. These results demonstrated that licochalcone E inhibits solid tumor growth and metastasis of breast cancer cells and these effects were mediated via the reduction of a wide variety of cytokines and chemokines, which subsequently inhibits tumor angiogenesis, lymphangiogenesis, proliferation, and metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 591. doi:1538-7445.AM2012-591
Abstract 599: Regulation of hypoxia-inducible factor stability by peptidyl prolyl isomerase Pin1
Authors: Han Hyeong-jun , Choi Bu Young , Choi Min-A , Hahn Young-il , Park Ji-Hyeon , Surh Young-Joon
Published: August 2012

Pin1 is an isomerase that binds to phosphorylated Ser/Thr-Pro motifs and regulates a subset of phosphoproteins through isomerization of the phosphorylated bonds. Pin1 has been reported to play an important role in differentiation, cell proliferation and immune responses. Interestingly, Pin1 is overexpressed in many types of cancer tissues including breast, prostate, lung and colon. However, molecular mechanism underlying its oncogenic functions has not been fully elucidated. Here, we report that Pin1 directly or indirectly interacts with hypoxia-inducible factor (HIF) -1α and -2α in HCT116 cells. Pin1 can bind both HIF-1α and -2α in vitro. We also found that Pin1 interacted more strongly with HIF-2α than with HIF-1α at the endogenous level. Pin1 binding may cause stabilization of HIF-1α and HIF-2α protein, given that their levels were significantly increased under hypoxic condition. Pin1 knockdown decreased the expression of HIF-1α and HIF-2α proteins and vascular endothelial growth factor (VEGF) mRNA under hypoxic conditions. On the other hand, overexpression of Pin1 resulted in an increase in HIF-1α protein levels in hypoxic cells, and enhanced hypoxia-induced VEGF transcriptional activation. These results suggest that Pin1 interplays with HIF-1α and -2α, and is a potential chemopreventive and therapeutic target.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 599. doi:1538-7445.AM2012-599
Abstract 60: KLF5 deletion promotes but does not initiate prostate carcinogenesis
Authors: Xing Changsheng , Fu Xiaoying , Sun Xiaodong , Dong Jin-Tang
Published: August 2012

KLF5 (Kruppel-like factor 5) is a basic transcription factor that is abundant in proliferating epithelial cells. Its locus at 13q21 is frequently deleted in human prostate cancer, suggesting a tumor suppressor function. Our previous study showed that TGF-beta, which is a differentiation signal for normal proliferating progenitor cells, acetylates KLF5 to reverse its function. Unacetylated KLF5 (unAc-KLF5) is pro-proliferative but acetylated KLF5 (Ac-KLF5) works with TGF-β to inhibit cell proliferation. Here we generated a Klf5-floxed mouse strain in which exons 2 and 3 of Klf5 are flanked by loxP sequences. By crossing Klf5-floxed mice with PB-Cre4 transgenic mice, we were able to delete the Klf5 gene specifically in prostatic epithelial cells. Because knockout of both Pten alleles induces prostate carcinoma, we also crossed Klf5-floxed mice with Pten-floxed mice to investigate Klf5 function in tumor progression. At different time points, prostates were collected and histological and molecular analyses were performed. We found that knockout of one Klf5 allele mainly increased cell proliferation and caused epithelial hyperplasia but was insufficient to initiate prostatic intraepithelial neoplasia (PIN). On the other hand, knockout of both Klf5 alleles mainly induced apoptosis in prostate epithelia. When combined with Pten knockout, the apoptosis was prevented due to the activation of PI3K survival signaling, making Klf5 null cells survive. With the deletion of one Pten allele, Klf5 deletion significantly increased cell proliferation and promoted the development of hyperplasia and PIN. When both Pten alleles were deleted, Klf5 deletion significantly enhanced tumor development, as indicated by increased tumor size and elimination of luminal structures. Immunohistochemical staining proved that cell cycle regulator p15 was downregulated in Klf5 knockout mice. Deletion of Klf5 also significantly induced phosphorylation of Erk1/2 MAPK and further increased Akt activity. In normal prostates, total Klf5 was detected in both luminal and basal cells of the prostate, while unAc-Klf5 and Ac-Klf5 were detected in basal and luminal cells respectively. In addition, oncogenic signals, such as Pten knockout, reduced Ac-Klf5 in differentiated luminal cells. In conclusion, deletion of Klf5 promotes cell proliferation and makes cells susceptible to other factor-induced carcinogenesis in the prostate, probably because of impaired proliferation-inhibitory function of Ac-Klf5.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 60. doi:1538-7445.AM2012-60
Abstract 601: PPARδ mediated p21 induction in aerodigestive preneoplastic cell lines
Authors: Miller Wendy , Wuertz Beverly , Ondrey Frank G.
Published: August 2012

PPARδ activating strategies are currently being tested preclinically and clinically in aerodigestive cancer prevention. Thiazolidinedione drugs like pioglitazone are clinically used for the treatment of diabetes and activate PPARδ as a primary target. P21/WAF1 is a cell cycle protein that is a cyclin dependent kinase inhibitor that reguylates cell cycle progression at the G1 phase; therefore its induction may be associated with cell cycle downregulation in precancerous cells experiencing increased proliferation. In our present study we examined the effects of pioglitazone on proliferation in human leukoplakia cells (MSK 1) and transformed lung (BEAS 2B) cells. We found that pioglitazone significantly inhibited cell proliferation in both cell lines in a dose dependent fashion at concentrations between 0 and 40 uM, as judged by MTT assays from 1-5 days. We found p21/WAF 1 induction by western blot within the first eight hours after the intitiation of treatment with pioglitazone, which were preceded by measureable increases in p21 induction on q PCR. In an analysis of an Affymetrix database of human head and neck tumors (41 tumors compared to 13 normal oral mucosa samples), we found significant dysregulation in several p21 activated kinases. We conclude the PPARδ activator, pioglitazone, can activate p21, which is associated with decreased proliferation in 2 aerodigestive preneoplastic cell lines. We also conclude that this gene may be a potential hypothesis driven biomarker in translational studies of pioglitazone as a chemoprevention agent for aerodigestive cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 601. doi:1538-7445.AM2012-601