bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 2059: HO-3867-induced apoptosis in hypoxic ovarian cancer cells occurs via ubiquitin-dependent degradation of signal transducer and activator of transcription 3 (STAT3)
Authors: McCann Georgia , Cohn David , Hideg Kalman , Kuppusamy Periannan , Karuppaiyah Selvendiran 
Published: July 2012

Abstract
Objectives: Hypoxia plays a role in tumorigenesis and the development of resistance to radio- and chemotherapy. We have shown that human xenograft tumors in mice are severely hypoxic and that hypoxic exposure increases the phosphorylation of STAT3 at the Tyr705 residue in A2780 cell lines and is associated with chemotherapeutic resistance. HO-3867, a novel curcumin analogue designed with our institution, induces cell cycle arrest and apoptosis via inhibition of the STAT3 signaling pathway. The goal of this study was to understand the mechanistic pathways involved. Methods: The study was performed using A2780 and SKOV3 human ovarian cancer cell lines grown under normoxic (21% O2) and hypoxic (1% O2) conditions for 24 hours. Hypoxia-exposed cells were subsequently treated with 10 or 20 uM of HO-3867 for 2 and 24 hours. The expression levels of pSTAT3, associated proteins, and apoptotic markers were evaluated by Western blot and RT-PCR. Quantification of apoptosis was performed by staining with Annexin V. We also examined cell viability and involvement of ubiquitin-dependent degradation of pSTAT3. Results: Treatment with HO-3867 under hypoxic conditions resulted in decreased protein expression of pSTAT3 Tyr705 and Ser727. Rapid downregulation of STAT3 correlated with accelerated ubiquitin-dependent degradation of Tyr705-phosphorylated STAT3. Treatment was associated with decreased levels of STAT3-targeting proteins VEGF, Bcl-2, Bcl-xL, and cyclin D1. RT-PCR revealed decreased BCL-2 mRNA expression with treatment. There was no change in expression of proteins upstream of STAT3 including pJAK1, JAK1, pTYK2, TYK2, SOCS1 and SOCS2. An induction in apoptosis contributed to inhibition of cell proliferation as HO-3867-exposed cells exhibited elevated levels of cleaved caspase-3, caspase-7, and PARP as well as an increase in apoptotic cell count measured by flow cytometry. Conclusion: Under hypoxic growth conditions, HO-3867 demonstrates cytotoxicity via inhibition of STAT3. The use of HO-3867 may be a potential adjunct in the treatment of hypoxia-mediated chemotherapy-resistant ovarian cancers.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2059. doi:10.1158/1538-7445.AM2011-2059
Abstract 206: High mobility group A1(HMGA1) proteins localize at the mitochondria and inhibit the p53-mediated intrinsic-apoptotic pathway
Authors: Esposito Francesco , Tornincasa Mara , Borbone Eleonora , Pierantoni Giovanna Maria 
Published: July 2012

Abstract
The high mobility group A (HMGA) non-histone chromosomal proteins play key roles in chromatin architecture and orchestrate the assembly of nucleoprotein complexes involved in gene transcription, replication, and chromatin structure. HMGA overexpression and gene rearrangements are frequent events in human cancer, but the molecular basis of HMGA oncogenic activity has not been completely elucidated. Recently, we have defined a new physical and functional interaction between HMGA1 and p53. This interaction modulates the transcription of p53 target genes such as Mdm2, p21waf1, Bax, Bcl-2, and inhibits p53-mediated apoptosis. Here we report that HMGA1 does not act only at transcriptional level but it has also a direct, anti-apoptogenic role at the mitochondria. In fact, we found that in mouse embryonic fibroblast (MEF) and several tumour cell lines overexpressing HMGA1, this protein is present at cytoplasmic level other than in the nucleus. Moreover, we demonstrate that HMGA1 stably localizes at the mitochondria, in which it binds Bcl-2, displacing it from the binding to p53, thus counteracting the release of cytochrome C. In agreement with this observation, the HMGA1-overexpressing cells show a significant reduction of cytochrome C release, after lethal dose of Ultraviolet (UV) light, whereas HMGA1-depleted cells are more susceptibile to UV treatment.
These data define a new localization of HMGA1 at the mitochondria level that allows HMGA1 to inhibit by a new mechanism the p53-mediated intrinsic-apoptotic pathway.
This mechanism may also have a role in the resistance of malignant cells to chemo- and radio-therapy, in particularly for the tumor cells harboring wild-type form of p53.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 206. doi:10.1158/1538-7445.AM2011-206
Abstract 2060: Comprehensive multiparametric assay of hypoxia and reactive oxygen species in live cells using different instrumentation platforms
Authors: Lebedeva Irina V. , Szczepanik Maciej , Pande Praveen , Patton Wayne F. 
Published: July 2012

Abstract
Hypoxia is a pathological condition in cells and tissue arising from oxygen deprivation. Cancer-associated hypoxia has been linked to drug treatment resistance, increased cell proliferation and metastatic potential, which overall contributes to poor patient prognosis. Many of the cellular responses to hypoxia are now known to be mediated by the production of reactive oxygen species at mitochondrial complex III. The importance of the maintenance of cellular oxygen supply requires further investigation into the role of ROS as hypoxia signaling molecules. Despite sustained interest in the association between hypoxia, ROS production and disease, methods for conveniently and reliably identifying and quantifying hypoxic cells as well as redox status in patients have remained elusive.
We designed and synthesized a series of non-fluorescent or weakly fluorescent aromatic compounds that become fluorescent once activated by hypoxic conditions. The probes were validated using a variety of in vitro cell-based hypoxia model systems involving exposure to hypoxia-inducing compounds (CoCl2, desferrioxamine or dimethyloxalylglycine) or by incubation in an anoxic environment (95% N2, 5% CO2). In the in vitro cell-based hypoxia model systems, all tested probes exhibited strong fluorescent cytoplasmic signal, readily detectable by different instrumental platforms. For the real-time profiling of both hypoxic and redox cellular status, these self-immolative hypoxia probes were combined with various ROS detection probes and stained samples were analyzed using conventional fluorescence microscopy or flow cytometry.
The described assay workflow facilitates rapid, reproducible, specific and relatively simple functional and quantitative detection of cellular oxygen status in a real-time format, and can readily be implemented on widely available instrumentation. The assay may be applicable to the screening of putative modulators of hypoxia or ROS production. Profiling of ROS is also possible when specific inhibitors of ROS are implied. The outlined fluorescence detection method offers an attractive approach for studying hypoxia and ROS pathways in a noninvasive manner, providing the ability for spatial and temporal resolution of cellular signaling events. The described multiparameter assay should find use in diverse applications relating to detection, quantification and localization of hypoxic cells in vivo and in vitro, as tools for the development of predictive assays or possibly as biosensors for early treatment monitoring and validation of potential endogenous hypoxia biomarkers and signaling molecules.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2060. doi:10.1158/1538-7445.AM2011-2060
Abstract 2067: Tumor cell survival under microenvironmental stress: Hypoxia and/or low glucose upregulate poline oxidase
Authors: Liu Wei , Sharma Anit , Phang James M. 
Published: July 2012

Abstract
Proline is a stress substrate which can be readily released from collagen in extracelluar matrix (ECM) initiated by matrix metalloproteinases accompanying tumor progression and invasion. Proline oxidase (POX) can metabolize proline to generate reactive oxygen species (ROS) for inducing apoptosis or autophagy; it also is a source of energy (ATP) under metabolic stress. However, the contribution of proline metabolism to tumorigenesis under concurrent hypoxia and low-glucose in the tumor microenvironment, has not been explored. In the present study, we showed that hypoxia and low glucose induced POX expression in HT29 colorectal cancer cells. The combination of low-glucose and hypoxia had additive effects on POX expression. Knockdown of HIF-1α, an important mediator of the hypoxic response, did not alter POX expression. Instead, inhibition of the activation of AMPK, the celluar energy sensor, by its antagonist (Compound C) blocked the upregulation of POX under conditions of either hypoxia or low glucose. Functional studies showed POX was consistently responsible for the maintenance of cell growth under hypoxia, low-glucose or with the combination of both. However, ATP and ROS assays showed that ATP production from POX was favored under low-glucose condition with or without hypoxia, whereas POX preferred ROS production with hypoxia. POX knockdown partially decreased hypoxia-induced prosurvival autophagy, which was also decreased by the antioxidant, N-acetylcysteine. Taken together, these results suggest that the induction of proline metabolism with hypoxia and/or low-glucose contributes an important mechanism by which tumor cells switch to a survival mode. These findings offer new insights into our understanding of energy metabolism in tumor cells beyond the well-recognized Warburg effect of aerobic glycolysis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2067. doi:10.1158/1538-7445.AM2011-2067
Abstract 2069: Regulation of nucleostemin by reactive oxygen species
Authors: Huang Min , Whang Patrick , Chodaparambil Jayanth V. , Pollyea Daniel A. , Kusler Brenda , Xu Liwen , Felsher Dean W. , Mitchell Beverly S. 
Published: July 2012

Abstract
Nucleostemin (NS) is a nucleolar-nucleoplasmic shuttle protein that is a key regulator of cell proliferation, binds p53 and Mdm2, and is highly expressed in tumor cells and embryonic stem cells. We have identified NS as a previously unreported target of redox regulation in transformed hematopoietic cells. NS oligomerization is present in HL-60 leukemic cells and Raji B lymphoblasts that express high levels of c-Myc and have high intrinsic levels of reactive oxygen species (ROS); exposure of these cells to reducing agents including N-acetylcysteine results in the dissociation of NS into monomers and dimers. On the other hand, exposure of other cell types that have relatively low levels of intrinsic ROS to low levels of H2O2 induces disulfide bond-mediated oligomerization of NS and, with prolonged exposure, immobilizes NS within the nucleolus, preventing its translocation to the nucleoplasm in response to nucleolar stress. Increasing levels of ROS also result in significantly increased NS protein stability. The redox-and oncogene-mediated regulation of NS was validated in a murine lymphoma tumor model in which c-Myc is overexpressed and in CD34+ cells from four patients with chronic myelogenous leukemia in blast crisis in which the BCR-ABL oncogene is expressed. In both instances, increased intrinsic ROS levels were associated with markedly increased expression of NS protein and oligomerization that was reversed by exposure of cells to N-acetylcysteine. These results demonstrate that NS is a highly redox-sensitive protein. Increased intracellular ROS levels, such as those that result from oncogenic transformation in hematopoietic malignancies, increase the oligomerization of NS, enhance its stability and most likely impair its ability to regulate Mdm2-p53 interactions in the nucleus.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2069. doi:10.1158/1538-7445.AM2011-2069
Abstract 207: PTEN contributes to p53 activation during skin transformation
Authors: Robbins Delira F. , Gu Xin , Liu Jianfeng , Ponville Jacqulyne , Morris Kerri , Zhao Yunfeng 
Published: July 2012

Abstract
Our previous studies have shown that the tumor suppressor p53 is activated and translocates to the nucleus, as well as, mitochondria during skin carcinogenesis. However, how p53, a short-lived protein is stabilized, and whether it works with other tumor suppressors remains unclear. We hypothesize that PTEN contributes to TPA-induced p53 activation in the early stages of skin carcinogenesis. Following TPA treatment, PTEN expression in the whole cell lysate was reduced; however, nuclear PTEN expression was increased, and the p53-PTEN interaction was detected via immunoprecipitation in murine skin epidermal JB6 P+ cells, an effect accompanied by an increase in the proapoptotic protein and p53 transcriptional target, Bax. In cell transfection experiments, knocking down PTEN expression via siRNA was sufficient to suppress p53 transcriptional activity as evidenced by decreased Bax expression. Similar effects were seen when p53 transcriptional activity was blocked by pifithrin-α, a specific p53 inhibitor that blocks p53 nuclear translocation. In addition, TPA-induced PTEN expression was significantly reduced in cells that were pre-treated with pifithrin-α. Our results indicate that the tumor suppressor, PTEN, promotes p53 activation in the early stages of TPA-mediated skin tumorigenesis to regulate the expression and transcriptional activity of p53. Therefore modulators of the PTEN- p53 complex can be therapeutically useful in the treatment of skin carcinogenesis and early-stage tumor promotion.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 207. doi:10.1158/1538-7445.AM2011-207
Abstract 2073: Curcumin analog 27 induced reactive oxygen species mediate loss of androgen receptor protein expression in human prostate cancer cells
Authors: Fajardo Alexandra M. , MacKenzie Debra A. , Deck Lorraine M. , Vander Jagt David L. , Thompson Todd A. , Bisoffi Marco 
Published: July 2012

Abstract
The androgen receptor (AR) is an established therapeutic target for prostate cancer. Therefore, agents that down-regulate AR expression may be effective for prostate cancer therapy. We show that the experimental therapeutic agent, curcumin analog 27 (ca27), induces the down-regulation of the AR in LNCaP and LAPC4 prostate cancer cell lines. Treatment with ca27 selectively inhibits AR mRNA expression, whereas ca27 did not alter mRNA levels for other steroid hormone receptors, such as the glucocorticoid receptor. In addition, ca27 decreases AR protein expression and increases AR protein ubiquitination within 3 hours. However, this rapid decrease in AR protein expression by ca27 is not mediated by proteasomal degradation. Interestingly, we observed an induction of reactive oxygen species (ROS) within 1 to 2 hours of ca27 treatment, which precedes AR degradation, leading to the hypothesis that ca27 mediates AR degradation through a cellular oxidative stress mechanism of action. In support of this hypothesis, the degradation of the AR following ca27 treatment is abrogated in the presence of the antioxidant, N-acetyl cysteine. Treatment with ca27 did not reduce cell viability by 24 hours suggesting that the increase in ROS and the inhibition of AR protein expression are independent of cell death. To further evaluate the cellular response to oxidative stress by ca27, we investigated the induction of a critical transcription factor activated as a cellular redox sensor, Nrf2. Treatment with ca27 lead to the increased transcriptional activation of Nrf2 as measured by an Nrf2-luciferase reporter assay. The ca27-induced Nrf2 activation was further supported by increased mRNA expression of the Nrf2-regulated genes NAD(P)H quinone oxidoreductase 1 and aldoketoreductase 1C1. This study begins to identify the mechanism of action of ca27-mediated AR protein degradation with the overall goal of gaining insight into targeting ROS-mediated AR down-regulation as a strategy for prostate cancer therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2073. doi:10.1158/1538-7445.AM2011-2073
Abstract 2077: Interactions between sulfiredoxin, S100A4 and non-muscle myosin IIA regulate cancer cell adhesion and motility
Authors: Bowers Robert R. , Manevich Yefim , Townsend Danyelle M. , Tew Kenneth D. 
Published: July 2012

Abstract
Sulfiredoxin (Srx) is an antioxidant protein that reduces over-oxidized catalytic cysteine residues of peroxiredoxins I-IV and catalyzes reduction of some S-glutathionylated proteins. We previously showed that Srx plays a role in cell migration and interacts with non-muscle myosin IIA (NM IIA; Bowers et al AACR 2010). The purpose of the present study was to extend our knowledge of the effect of Srx on cell adhesion and migration. Immunoprecipitation of Srx from non-small lung cancer (A549 cells) revealed a number of Srx-interacting proteins including NM IIA and S100A4. NM IIA plays a central role in the control of cell adhesion and migration, and S100A4 is a key regulator of NM IIA activity that is linked to cancer metastases. Adhesion assays showed that A549 cells over-expressing Srx have reduced adhesion to fibronectin-coated dishes and decreased levels of Tyr397-phosphorylated focal adhesion kinase (p-FAK). Conversely, Srx knockdown by shRNA increased A549 cell adhesion to fibronectin and p-FAK levels. Srx over-expression in A549 cells increased actin stress fiber formation and altered focal adhesion formation. Depletion of Srx in A549 cells resulted in decreased actin stress fiber formation and also altered sites of cell:extracellular matrix adhesion. In silico molecular modeling of an Srx-S100A4 homodimer complex showed close proximity (∼13Å) of the single Cys99 of Srx to the Cys85 of S100A4. The calculated binding constant for the Srx-S100A4 interaction indicated reasonable affinity (KD∼ 62 nM). This affinity was not dependent upon disulfide bonding, since mutation of Srx residue Cys99 to Ser resulted in increased affinity (KD ∼22 nM). In vitro S-glutathionylation of Cys85 of S100A4 markedly increased its affinity to Srx (KD∼4 nM), but had no effect with the inactive Srx C99S mutant. Srx over-expression produced a doubling of the basal cellular level of free Ca2+ suggesting that the protein:protein interactions altered the capacity of S100A4 to bind Ca2+. Our data show that Srx may play important role in S100A4-mediated cancer cell cytoskeletal remodeling and motility and could potentially be a target for development of specific anticancer therapies.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2077. doi:10.1158/1538-7445.AM2011-2077
Abstract 2078: PERK-mediated autophagy promotes Myc-induced transformation and tumorigenesis
Authors: Hart Lori S. , Cunningham Tom , Datta Tatini , Liu Huayi , Koong Albert C. , Fuchs Serge , Diehl J. Alan , Ruggero Davide , Koumenis Constantinos 
Published: July 2012

Abstract
The Unfolded Protein Response (UPR) is a coordinated cellular homeostatic program initiated by the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) lumen, with the ultimate fate of the cell depending on both the intensity and persistence of the stress. We have previously shown that tumor cell survival under hypoxic stress is dependent on the UPR kinase PERK, as the growth of PERK-null tumors is significantly inhibited in vivo. The transcription factor c-Myc, the target of chromosomal translocation and gene amplification during the development of many human cancers, upregulates genes involved in ribosome biogenesis and increases the rate of protein synthesis, therefore, we hypothesized the UPR is activated by c-Myc overexpression. Using in vitro and in vivo models of c-Myc expression, we demonstrate that c-Myc activates PERK-dependent phosphorylation of eIF2α and upregulates the downstream effectors, ATF4 and XBP1s. UPR activation contributes to cell survival during c-Myc induced transformation via the induction of autophagy, as measured by LC3 processing and p62 degradation. Inhibition of PERK dramatically reduces c-Myc induced transformation and tumor growth in nude mice. We are currently developing a lymphoma mouse model to test the strategy of PERK inhibition orthotopically. We have established a role for c-Myc in the cellular response to ER-stress and our results highlight a role for PERK inhibition in the treatment of malignancies characterized by c-Myc overexpression, such as lymphomas.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2078. doi:10.1158/1538-7445.AM2011-2078