bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A3: mTOR signaling and tamoxifen response in postmenopausal breast cancer
Authors: Bostner Josefine , Karlsson Elin , Pandiyan Muneeswaran Jayachandra , Fornander Tommy , Nordenskjöld Bo 
Published: March 2013

Abstract
mTOR is a central, frequently altered, node for the complex growth signaling in breast cancer. Activation of the PI3K/Akt/mTOR-pathway seems to be one of the mechanisms for patients recurring after adjuvant endocrine treatment. Growth factor signals promote phosphorylation of the estrogen receptor alpha (ER), thereby altering the receptor conformation, stability and its response to tamoxifen treatment. Ongoing studies are investigating the possibility to inhibit the mTOR pathway in addition to endocrine treatment or after endocrine treatment failure. In the present retrospective study, a postmenopausal early breast cancer cohort of 812 patients, randomized to tamoxifen or no endocrine treatment, was analyzed according to the protein expression of mTOR phosphorylated on serine 2448. Downstream targets of mTOR are the S6Kinases, S6K1 and S6K2. S6K1 is thought to directly phosphorylate the ER on serine 167. Here, a positive correlation between p-mTOR and p-ERs167 was shown. However, no correlation was detected between p-mTOR and p-ERs305, indicating that the active mTOR signaling specifically targets the ERs167 residue. Activated 4EBP1, another common mTOR target, did not correlate with the p-mTOR protein expression. No prognostic value, independently of cut-off, was seen for p-mTOR expression in this material.
Analyses of p-mTOR as a tool for treatment prediction showed that negative, low and medium expression in the tumor did not affect the patients response to tamoxifen, p=0.0001. High and abundant expression decreased the tamoxifen sensitivity to a non-significant degree, p=0.34. An ER-positive/PgR-positive selection further improved the hypothesis of p-mTOR being an indicator of tamoxifen resistance. Where the p-mTOR negative group responded well to treatment (p&lt;0.00001), compared with the p-mTOR positive group, where the treated group did not separate significantly from the controls (p=0.71).
In conclusion, the results indicate that risk of recurrence after tamoxifen treatment may increase in patients with high mTOR kinase activity.
Abstract A45: Signaling Events Associated with Cytoprotective Induction of Nitric Oxide Synthase in a Photodynamic Therapy Model
Authors: Bhowmick Reshma , Girotti Albert W. 
Published: March 2013

Abstract
Photodynamic therapy (PDT) employs a photosensitizing agent, molecular oxygen, and photosensitizer-exciting light to produce reactive oxygen species that lead to tumor eradication. Nitric oxide (NO) produced by tumor or tumor vasculature cells could be pro-carcinogenic by inhibiting apoptosis and/or promoting angiogenesis and tumor growth. We recently showed that photoactivation of 5-aminolevulinic acid (ALA)-generated protoporphyrin IX in mitochondria of COH-BR1 breast tumor cells strongly upregulated inducible nitric oxide synthase (iNOS) and steady state NO level in these cells. Including the iNOS inhibitor 1400W during photochallenge dramatically enhanced caspase-9 activation and Annexin-assessed apoptotic cell killing while reducing NO production assessed by the intracellular NO probe DAF-2DA. Short hairpin RNA (ShRNA)-based iNOS knockdown (kd) produced similar results, confirming iNOS involvement. An apoptosis-promoting effect of iNOS inhibition was also observed when breast MDA-MB231 and prostate PC-3 cancer cells were subjected to ALA/light stress. We have now examined the signaling events associated with iNOS-mediated hyperresistance of COH-BR1 cells using a combination of immunocytochemistry, western blotting, immunoprecipitaion, and iNOS-kd methods. A soluble guanylyl cyclase inhibitor failed to stimulate ALA/light-provoked apoptosis, ruling out cGMP involvement in stress resistance. ALA/light activated PI3-kinase-dependent signaling via phosphorylation-inactivation of the tumor suppressor PTEN, leading to phosphorylation-activation of pro-survival Akt. Inhibition of PI3K by Wortmannin prevented ALA/light-induced Akt activation as well as iNOS upregulation while enhancing apoptotic photokilling. Moreover, photostress activation of PI3K/Akt was accompanied by a cytosol-to-nucleus translocation of the iNOS transcription factor NF-κB, and an inhibitor of NF-kB activation prevented iNOS induction while stimulating apoptosis. Furthermore, iNOS-kd as well as 1400W treatment resulted in intensified and more prolonged activation of MAP kinases JNK and p38α by ALA/light stress. In addition, photostressed iNOS-kd cells exhibited p53 upregulation and Survivin inactivation/downregulation. The following general mechanism of NO-based cytoprotection is suggested from these and related findings: Photostress activation of PI3K/Akt suppresses pro-apoptotic MAP kinases and p53 while upregulating/activating Survivin via NF-κB-mediated induction of iNOS/NO. This study provides important new insights into photostress-elicited pro-survival signaling that could reduce PDT effectiveness, and suggests iNOS inhibitor-based interventions for counteracting this.
(Supported by NIH Grant CA70823 and a grant from the MCW Cancer Center.)
Abstract A51: Antiproliferative activity of F14512, a novel polyamine-vectorized drug, on multidrug resistant cancer cells
Authors: Créancier Laurent , Guilbaud Nicolas , Annereau Jean-Philippe , Brel Viviane , Marionneau-Brossard Marie-Laure , Offrete Vanessa , Verdier Jérôme , André Karine , Fournier Emmanuel , Guminski Yves , Kruczynski Anna 
Published: March 2013

Abstract
F14512 is a novel vectorized topoisomerase II inhibitor currently in phase I clinical study in AML. Briefly, F14512 combines a polyamine (spermine) chain with an epipodophyllotoxin warhead. An enhanced antitumor effect associated with a large therapeutic index results from this specific targeting of cancer cells through polyamine transport system. One of the most important limitations in chemotherapeutic treatment is acquired or innate drug resistance. To investigate this phenomenon for F14152, we selected A549 NSCLC cell lines upon F14512 treatment by increasing doses selection, and characterized the profile of resistance in term of ABC transporter expression and modification of topoisomerase II expression. As results, resistant cell lines were selected after 46 passages and 32 treatment of F14512 with doses ranging 0.25 to 4 IC50 of inhibition of proliferation, over a period of 9 months. As key observation, the intense selection pressure led solely to a moderated shift of EC50 of proliferation, not mediated through MDR1 nor MRP1, but more likely attributable to reduction of topoisomerase II expression. Moreover, we demonstrated that F14512 retains significant antiproliferative activity of F14512 on cell line overexpressing MDR1: CEM selected in vinblastine, A-549 in vinflunine, and P388 in vinorelbine, with a striking enhanced impact on the later model. According to these first investigations, we conclude that MDR1 would not be involved in the resistance mechanism against F14512. We are investigating hypotheses potentially explaining the collateral sensitivity to this novel polyamine derivative on MDR1 expressing P-388 cells.
Abstract A53: Bayesian Network Inference Modeling Reveals Novel Regulators of Cell Cycle Progression and Survival
Authors: Gendelman Rina , Xing Heming , Sarde Preeti , Mirzoeva Olga K. , Feiler Heidi , Gray Joe W. , McDonagh Paul , Khalil Iya , Korn W. Michael 
Published: March 2013

Abstract
Molecular networks governing responses to targeted therapies in cancer cells are complex dynamic systems that demonstrate non-intuitive behaviors. We applied a novel computational strategy to decipher causal relationships between signaling network components. Gene networks were constructed from global gene expression profiles to model G1-S cell cycle arrest as a consequence of inhibition of MEK, a key component of the oncogenic RAF-MEK-ERK signal transduction pathway. Simulation of causally driven models generated a ranked list of 12 testable hypotheses, which confirmed role of known cell cycle regulators (CCND1, CCNE2, and CDC25A) and identified novel drivers of G1-S transition (IER2, TRIB1, C14ORF133). Validation confirmed 11 out 12 predictions. Second model which inferred causal relationships between genes lead to discovery of TRIB1 (tribbles homolog of Drosophila) as a regulator of NFkB-dependent gene expression. TRIB1 also mediates cross-talk to the NFκB pathway by enhancing p100 and IκBα-phosphorylation and degradation thus regulating cell survival and expression of cytokines crucial for tumor-stroma interaction. In agreement with this, knock-down of TRIB1 results in induction of apoptosis and sensitizes cells to cell killing induced by the death-receptor agonist TRAIL via upregulation of TRAIL receptor, DR5. Thus TRIB1 is a central regulator of cell cycle and survival and represents a potential therapeutic target. Therefore, applying REFS (Reverse Engineering Forward Simulation) to analyze gene expression profiles maximizes our ability to extract knowledge from experimental data.
Abstract A57: Chondroitin sulfate proteoglycan 4(CSPG4) Mediates Melanoma Cell Survival During PI3K and mTOR Inhibition
Authors: Javaid Sehrish , Wanshura Leah E. Colvin , Dudek Arkadiusz Z. 
Published: March 2013

Abstract
Background: Early development of resistance to therapy remains a major cause of cutaneous malignant melanoma treatment failure. Chondroitin sulfate proteoglycan 4 (CSPG4) is robustly expressed in a majority of metastatic melanomas. Previous work has shown CSPG4 to promote MAPK, PI3K and FAK activation, suggesting that CSPG4 represents a potential avenue for oncogenic growth and cell survival in response to chemotherapy. The PI3K-AKT-mTOR pathway regulates the cell growth and motility in the presence of nutrients. The inhibition of AKT and mTOR independently was shown to reduce the melanoma cell survival and enhanced the sensitivity of these cells to cisplatin. PF-05212384 (PKI-587) is a dual PI3K/mTOR inhibitor in clinical trials. We hereby report that the expression of CSPG4 on the melanoma cells caused them to become less responsive to the therapy with a dual PF-05212384.
Material and methods: Melanoma cell lines that stably expressed CSPG4 were selected for this study. The expression of CSPG4 was knocked down by using lentivirus-transduced shRNA. Cell survival assays were performed to compare the inhibitory effects of the drug in CSPG4 expressing and non-expressing cell line. Wound healing migration assays were performed to examine the cell motility and migration. The activation of PI3K-mTOR pathway was analyzed by phosphorylation of downstream effectors for their activation using Western blotting.
Results: Melanoma cells expressing active CSPG4 showed less sensitivity to the inhibitor. The average cell viability after treatment with maximum dose was 47.94% and 35.76% for CSPG4 positive 1205LU and WM1341D melanoma cell lines respectively, while the CSPG4 negative WM1552C showed an average cell viability of 19.07%. The difference in cell viability was statistically significant.(p&lt;α=0.05)for higher doses. The suppression of CSPG4 using the shRNA sensitized the CSPG4 positive cell lines to the PI3K/mTOR inhibition. (p&lt;α=0.05). The maximum effect was seen in the WM1341D where the cell viability was reduced at maximum dose to 26.30% as compared to 50% in non-targeting shRNA transduced control. The CSPG4 positive cell lines resisted the deactivation of p70Sk, a downstream effector of mTOR and had enhanced phosphorylation of transcription repressor 4E-BP1.At higher doses the cleavage of caspase to its activated forms, which is necessary for execution of apoptosis was reduced in the CSPG4 positive cell lines. The CSPG4 positive cells showed more motility as compared to the controls.
Conclusion: This data supports the hypothesis that the CSPG4 is involved in inducing resistance in melanoma cells in response to the therapeutic challenge with the dual PI3k/mTOR inhibitor. The study highlights the need of using multiple treatment strategies to treat melanoma.
Abstract B10: Overcoming resistance to B-Raf targeting agents using LPD nanotechnology
Authors: Chung Chin-Ying , Wang Yuhua , Sheng Wei-Yun , Tseng Yu-Cheng , Dick Taryn , Huang Leaf , Robertson Gavin 
Published: March 2013

Abstract
Constitutively active mutant V600EB-RAF is present in 50% to 60% of sporadic melanomas and vemurafenib is a selective inactivating inhibitory drug. While the compound is initially effective in 80% patients, most of the patients eventually developed more invasive resistant disease. Unraveling the mechanisms leading to the development of vemurafenib resistance is key to developing better treatment strategies that can overcome the process and provide patients with more effective treatment options. Here we show that vemurafenib inhibits ERK activity to negatively regulate tumor suppressor Sprouty4 expression to increase Akt3 activity, leading to the development of drug-resistant melanomas. Combining vemurafenib with sigma receptor targeted LPD nanoparticle technology containing Akt3 siRNA and suppressor Sprouty4 plasmid simultaneously inhibit MAPK and Akt3, preventing resistant tumor development in xenografted mice. Our studies have identified a novel mechanism leading to the development of resistant melanoma following vemurafenib treatment and development of a novel melanoma cell targeting nanotechnology-based therapeutic agent for combating the development of resistance.
Abstract B13: Modeling BRAF inhibitor resistance in genetically engineered mouse models of melanoma
Authors: Kwong Lawrence N. , Jiang Shan , Chin Lynda 
Published: March 2013

Abstract
Resistance to BRAF inhibitors in melanoma poses a serious clinical challenge to this otherwise potent therapy. Acquired resistance has been shown to arise from a wide variety of genetic and epigenetic sources including NRAS or MEK mutations, elevated PDGFRB or IGF1R levels, and BRAF splice variants. Many of these mechanisms were discovered in vitro and validated in patients, demonstrating the faithfulness of cell culture data. Nevertheless, cell culture may not be able to capture all sources of resistance, particularly if they involve interaction with the stroma. We have therefore undertaken the generation of de novo BRAF inhibitor resistance in a novel mouse model of melanoma, the iBIP (inducible Braf, Ink/Arf, Pten) model. Similar to existing BRAF mouse models, topical tamoxifen restricts BRAFV600E expression and PTEN loss to targeted melanocytes. The added utility of this model is the ability to extinguish BRAF transgene expression via withdrawal of doxycycline from the diet. We show that the molecular profile and tumor regression phentoype of BRAF inhibitor treatment in this model faithfully mirrors genetic BRAF extinction. Treatment with the BRAF inhibitor caused stable and complete tumor regression. However, long-term treatment with the inhibitor failed to generate de novo resistant melanomas. We hypothesized that the relatively stable mouse genome was not generating potentially resistance-conferring mutations or alterations at a fast enough rate. We therefore generated genomic instability in the iBIP model by crossing it onto a telomerase-deficient background. Melanomas in this model acquired resistance at a rate of approximately 30% after a short interval of sensitivity. Currently, characterization of these tumors is being carried out, including whole-exon sequencing, RNA-sequencing, and array comparative genomic hybridization. Preliminary aCGH data show a recurrent, whole-chromosome gain in two resistant tumors that is not present in untreated or sensitive tumors. Other efforts are focused on generating a large bank of resistant tumors, checking cross-resistance among BRAF inhibitors, and identifying any stromal and immune changes. This in vivo model of acquired BRAF inhibitor resistance provides an important complement to known resistance mechanisms and may also serve as a preclinical platform to test anti-resistance countertherapies.
Abstract B42: Heat Shock Protein 27 (HSP27, HSPB1) is up-regulated by MET kinase inhibition and limits the effectiveness of inhibitors
Authors: Musiani Daniele , Rivera Alberto Ramirez , Konda John David , Pavan Simona , Torchiaro Erica , Olivero Martina , Di Renzo Maria Flavia 
Published: March 2013

Abstract
The receptor for the hepatocyte growth factor (HGF) is encoded by the MET oncogene and its activation results in cell growth, survival, motility and invasiveness. Deregulated HGF/MET signaling is observed in many tumors and both HGF and MET are attractive candidates for targeted therapies. Unexpectedly, we found that in ovarian cancer cells the activation of the MET receptor downmodulated the expression of the small heat shock protein 27 (HSP27), which functions as a molecular chaperone and as an antiapoptotic protein. In MET addicted gastric carcinoma cells, where MET is constitutively active, MET kinase inhibition by JNJ-38877605 up-regulated HSP27 expression. More importantly, in these gastric carcinoma cells suppression of HSP27 was alone able to induce cell death and increased cell susceptibility to MET inhibition. HSP27 suppression did not affect MET stability and phosphorylation, but increased activation of caspase 3, which is a known HSP27 client protein. Regulation of HSP27 expression by MET signaling occurred at transcriptional level, as confirmed by the use of HSP27 promoter in a reporter assay. It was not due to the engagement of HSF1, the master key transcription factor regulating HSPs expression, but depended on MEK activation and resulting HIF 1alpha stabilization. MEK inhibition and HIF 1 alpha silencing resulted in the induction of HSP27, suggesting a direct or indirect transcriptional repression. Altogether data show that MET activation down-regulates and MET inhibition up-regulates HSP27 expression, and that HSP27 increased expression protects cells from death induced by MET inhibitors. Therefore, in therapies with MET targeting agents, HSP27 increase might impair the effectiveness of MET inhibitors. As it is known that HSP27 protects cells for chemotherapeutics, data suggest that HSP27 might strongly affect combinatorial treatments.
Abstract B57: Overcoming Acquired Resistance in Philadelphia-Positive (Ph+) Leukemia
Authors: Khateb Mamduh , Najajrah Yousef , Ruthardt Martin , Mahajna Jamal 
Published: March 2013

Abstract
Chronic myeloid leukemia (CML) is characterized by the presence of p210Bcr-Abl which exhibits an abnormal kinase activity. Selective Abl kinase inhibitors (AKIs) have been successfully established for the treatment of CML. Despite high rates of clinical response, CML patients can develop resistance. Acquired resistance to AKIs in Ph+ leukemia is mostly due to the acquisition of point mutations within the Bcr-Abl Kinase by either reducing the affinity of the kinase domain to the ATP-competitor or stabilizing the active confirmation of the Abl kinase domain. Thus, acquired drug resistance in Philadelphia positive (Ph+) leukemia and in particular the gatekeeper mutation, T315I, to Abl kinase inhibitors (AKIs), represents a major obstacle in overcoming Bcr-Abl positive leukemia. T315I mutation is refractory to clinically available AKIs, as well as to Abl allosteric inhibitors such as GNF-2.
In this study, we documented cooperation between AKIs and GNF-2 in inhibiting proliferation and clonigenicity of Ba/F3 cells carrying T315I mutated Bcr-Abl. Interestingly, cooperation was most evident between dasatinib and GNF-2. Cooperation was also documented in the ALL SupB15 cell line. Cooperation in cells carrying native Bcr-Abl gene was mediated by Bcr-Abl. In contrast, proliferation and clonigenicity inhibition of Ph+ cells harboring the T315I mutation was not mediated by Bcr-Abl, but apparently by Bcr-Abl-independent mechanisms.
Moreover, previously we have identified oleic acid as the active component in the mushroom Daedalea gibbosa who inhibited the kinase activity of Bcr-Abl apparently by allosteric inhibition. Here, we report that derivatives of oleic acid, oleylamine-carbonyl L-valinol and oleylamine-carbonyl D-valinol, inhibited the activity of the native and T315I mutated Bcr-Abl. Furthermore, oleylamine-carbonyl L-valinol and oleylamine-carbonyl D-valinol, exhibited higher activity toward the oncogenic Bcr-Abl in comparison to native c-Abl in SupB15, Ph-positive ALL cell line.
Abstract B65: MicroRNAs in cancer drug resistance and sensitivity
Authors: Zhu Jian 
Published: March 2013

Abstract
microRNAs are small noncoding RNAs of 18–25 nucleotides that have been shown to regulate gene expression posttranscriptionally and play fundamental roles in diverse biological and pathological processes. MiRNApedia is an in silico discovery tool designed to integrate all microRNA-related information including genetic variation, gene expression, epigenetic regulation, pathways, diseases, clinical outcomes and particularly drug actions. The system documented more than 1,000 microRNAs and 600 therapeutic and experimental compounds including well-known cancer drugs cisplatin, doxorubicin, 5-flouracil, gemicitabine, paclitaxel, docetaxal, imatinib, vorinostat, sorafenib and gefitinib etc. For each compound, microRNAs and genes related to its sensitivity and function were compiled from literature and used to construct comprehensive drug-gene-microRNA networks. MicroRNAs played important roles in determining resistance and sensitivity of cancer drugs. For example, miR-21 reduced sensitivities to daunorubicin, topotecan, 5-FU, taxol, doxorubicin, docetaxel, ara-C, arsenic trioxide, gemcitabine and dexamethasome, while miR-146a increased sensitivity to bleomycin and over-expression of miR-221 conferred resistance to tamoxifen. Multiple microRNAs might be involved in the efficacy of a single drug. MiRs -98, -214, -106a, -125b and -630 contributed to cisplatin resistance, while -451, -181a, -148a, -138 and let-7i enhanced its sensitivity. Meanwhile, cisplatin was shown to down-regulate miRs -150 and -106 while up-regulated miRs -34, -16, -17-5p and -125. Drug combination would be the choice to overcome resistance in mono-therapies. Prior to experimental testing, the combination effects of multiple drugs could be assessed computationally by combining annotated information in microRNA targets, signaling pathways and transcriptional regulations etc. For example, trichostatin A (TSA), a HDAC inhibitor, might enhance sensitivity of cisplatin by up-regulating p53 and its transcriptional target miR-34 which subsequently down-regulated BCL2, a well-known drug resistance factor. However, if miR-125b, another transcriptional target of p53, was up-regulated, the combination might turn out to be antagonistic. Mechanistically, miR-125b targeted BAK1 which was required for cisplatin sensitivity. Such in silico modeling exercises not only predicted synergism or antagonism, but also identified underlined drivers which could serve as biomarkers for desired therapeutic effects. The potential biomarkers identified by the network modeling approach could be used to guide selection of experimental system (e.g., cell line models) and monitor the combination effectiveness. The present study devised a mechanism to systematically capture microRNA information in regards to cancer drug resistance and established a computational framework to identify potential drug combinations to overcome resistance in cancer therapies.