bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 701: A mechanistic study of mdr1a gene regulation in vivo using bioimaging
Authors: Gu Long , Lin Min , Higgins Kathleen , Forman Barry , Kane Susan E. 
Published: June 2012

Abstract
The human P-glycoprotein (Pgp) encoded by the MDR1 gene is as a transmembrane drug transporter that mediates the efflux of drugs from cells. It confers multidrug resistance in cancer cells that overexpress MDR1. In addition, basal expression of MDR1 in organs such as liver, kidney, and colon affects the pharmacokinetics of drug uptake and excretion for agents that are substrates for Pgp transport. Nuclear receptors such as SXR and CAR have been suggested as possible master regulators of xenobiotic- and drug-inducible expression of MDR1 and of other genes involved in drug metabolism in drug processing organs. However, the mechanism of MDR1 regulation in tumors or in normal, non-malignant tissue, particularly in response to xenobiotics, has yet to be demonstrated in vivo. To facilitate the mechanistic study of MDR1 gene regulation in vivo, we previously reported a mouse model that allows non-invasive bioimaging of the mdr1 gene expression in vivo and in real time by inserting a firefly luciferase (fLUC) gene into the murine mdr1a genetic locus by homologous recombination.1 To determine the role of PXR, the murine homologue of SXR, in drug-mediated induction of mdr1a, we crossed mdr1a.fLUC mice with PXR knockout mice. Pregnenolone-16α-carbonitrile (PCN), a known SXR substrate, induced intestinal mdr1a.fLUC expression in the PXR wild type background but not the PXR knockout background. Notably, mdr1a.fLUC was re-inducible over three rounds of drug dosing, which could be measured longitudinally in our real-time assessment of gene expression. TCPOBOP, a known CAR ligand, induced mdr1a.fLUC in both the wild type and knockout background, consistent with the idea that mdr1a is also regulated by the CAR nuclear receptor. The chemotherapeutic agent docetaxel induced mdr1a.fLUC in the PXR wild type background but induction was dramatically reduced in the PXR KO background; paclitaxel gave only low-level induction in both genetic backgrounds. This result is consistent with the reported ligand specificity of mouse PXR. Future studies in a CAR-null background will determine if the observed effect of paclitaxel on mdr1a expression is mediated through CAR. These studies demonstrate the utility of our murine imaging model for the in vivo study of mdr1 gene regulation in real time. Studies with additional chemotherapeutic drugs and genetic backgrounds will establish the variety of agents capable of inducing mdr1a at the transcriptional level and the trans-acting factors that are involved in such induction.
1Gu et al. Proc Natl Acad Sci 106:5394-5399 (2009)
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 701. doi:10.1158/1538-7445.AM2011-701
Abstract 704: Upregulation of the human equilibrative nucleoside transporter 1 (hENT1) expression by indole-3-carbinol (I3C) in pancreatic cancer cell lines
Authors: Wang Honggang , Word Beverly , Lyn-Cook Berverly 
Published: June 2012

Abstract
Pancreatic adenocarcinoma is the fourth most common cause of death in cancer in the Western world. In the past years, gemcitabine (GEM) has become the standard chemotherapeutic agent for patients with pancreatic cancer. However, a substantial number of patients fail to respond to therapy due to inherent or developed GEM chemoresistance. GEM is transported into cells mainly by the human equilibrative nucleoside transporter 1 (hENT1). Overexpression of hENT1 mRNA and protein in pancreatic carcinoma is known to correlate with better outcomes. In recent years, indole-3-carbinol (I3C), a dietary compound in cruciferous vegetables, has been shown to alter cancer cell survival by inducing apoptosis in vivo. I3C has also been shown to reverse multiple drug resistance by inhibiting efflux transporter, P-glycoprotein (P-gp) expression. In this study, the potential of I3C to modulate hENT1 expression and activity was evaluated in a panel of human pancreatic cancer cell lines, AsPC-1, BxPC-3, MiaPaca2, PANC-1 and PL-45. Our data showed that I3C at 50 and 100 uM significantly increased hENT1 mRNA and protein expression in BxPC-3 cell, MiaPaca2 cells and PANC-1 cells compared with the vehicle controls. In contrast, no such effect was observed in AsPC-1 and PL-45 cells with same treatment. The potential synergistic cytotoxic effect of I3C and GEM was also examined in all five pancreatic cancer cell lines. Pancreatic cancer cells were incubated with or without I3C at 50 uM for 24 h and then treated with GEM at different concentrations with or without I3C at 50 uM and a specific hENT1 inhibitor, NBMPR, at 50nM for 48 hours. MTS assay was used for cell viability measurement. Our data showed that I3C decreased IC50 by 6.8, 8.1 and 8.4 folds in PANC-1, MiaPaca2 and BxPC-3 cells respectively, and only 2.7 and 2.0 folds in AsPC-1 and PL-45 cells respectively, compared with GEM alone treated cells. Investigation also found that NBMPR, a specific inhibitor of hENT1, only abrogated a part of the augmented effect of I3C in response to GEM in all five pancreatic cell lines.
The present study provides evidence that increasing hENT1 expression is a novel mechanism of the antitumor effect of I3C. The combination of GEM and I3C may be an effective strategy to overcome the GEM chemoresistance in pancreatic cancer patients. This affirms our hypothesis that I3C could be an adjuvant therapy improving the response to GEM treatment in patients with pancreatic cancer.
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 704. doi:10.1158/1538-7445.AM2011-704
Abstract 708: Integrated analysis of drug resistance networks in breast cancer
Authors: Komurov Kakajan , Tseng Jen-Te , Muller Melissa , Ram Prahlad T. 
Published: June 2012

Abstract
Targeted inhibition of HER2 tyrosine kinase receptor presents a promising strategy in the treatment of HER2-positive breast cancer patients. However, despite favorable response during the acute phase, majority of patients develop resistance to anti-HER2 drugs during the chronic phase of treatment. Here, we developed a cell culture model of chronic lapatinib (a dual inhibitor of EGFR and ERBB2 receptor tyrosine kinases) treatment by continuous passaging of HER2-overexpressing SKBR3 cells in increasing doses of lapatinib over a year. The resultant cell line, SKBR3-R, is almost 100-fold more resistant to lapatinib-induced growth inhibition when compared to the parental line. We have verified that this difference in lapatinib sensitivity is not due to altered expression or signaling at the level of HER2 or HER3 receptors in SKBR3-R cells. By integrating genome-wide gene expression profiling with our novel network-based genomic data analysis approach, we show that 1) cell toxicity mediated by acute lapatinib treatment in HER2-positive cells is associated with nutrient starvation and energy stress, and 2) chronic lapatinib treatment leads to the activation of compensatory cellular networks involved in the response to nutrient starvation, which confers resistance to lapatinib-induced cell death. Accordingly, while imposing a glucose starvation response phenotype on SKBR3 cells protects from lapatinib-mediated cell death, pharmacological inhibition of the nutrient starvation response in SKBR3-R cells reverses lapatinib resistance. In order to see if these networks play a role in breast cancer pathogenicity within clinical settings, we carried out a detailed network-based correlations of tumor gene expression profiles of breast cancer patients with their clinical data. Importantly, we found that the metabolic networks associated with lapatinib resistance are also associated with poor outcome within clinical settings. This study implicates nutrient deprivation response as a major factor in the acquired resistance of breast cancer cells to lapatinib, and suggests novel targets for combinatorial therapy of HER2-positive breast 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 708. doi:10.1158/1538-7445.AM2011-708
Abstract 717: JAK2/STAT3 induces erlotinib-resistance in lung cancer cells harboring EGFR-activating mutations
Authors: Harada Daijiro , Harada Daijiro , Takigawa Nagio , Ohashi Kadoaki , Ichihara Eiki , Kubo Toshio , Takeda Hiromasa , Kashihara Hiromi , Hotta Katsuyuki , Tanimoto Mitsune , Kiura Katsuyuki 
Published: June 2012

Abstract
Epidermal growth factor receptor (EGFR) inhibitors, including the small molecule tyrosine kinase inhibitors such as gefitinib and erlotinib, have demonstrated promising effects in non-small cell lung cancer harboring EGFR-activating mutation. But even in the patients with an initial dramatic response, acquired resistance to the EGFR tyrosine kinase inhibitor develops almost without exception after varying periods of time, usually 6-12 months. Secondary mutations such as T790M mutation in EGFR and/or amplification of the gene encoding the MET receptor tyrosine kinase account for some of the resistance. However, tumors from approximately 40% of patients with acquired resistance do not have the known mechanisms.
We generated an erlotinib-resistant cell line (PC-9/ER3) from PC-9 that harbored the delE746-A750 mutation, by exposing the cell line to erlotinib for 12 weeks. The cytotoxicity of the drugs for the cells was evaluated using MTT assay. The drug concentration required to inhibit the growth of tumor cells by 50% (IC50) for 96 h exposure was used to evaluate the cytotoxicity. Protein expression was determined by Western blotting.
The PC-9/ER3 cells were 250-fold more resistant to erlotinib than the parental cells, and were stable for 20 weeks or longer without erlotinib exposure. The resistant cells harbored neither T790M mutation nor MET gene amplification. Erlotinib suppressed pEGFR and pMAPK, however, increased pSTAT3 in both PC-9 and PC-9/ER3 cells. No differences were observed in the IC50 values of JSI-124, a JAK2 inhibitor that suppresses STAT3 phosphorylation, between the parental and resistant cells. The PC-9/ER3 cells restored sensitivity to erlotinib when combined with JSI-124 (0.05 µM), even though the IC50 values of erlotinib combined with JSI-124 in the PC-9 cells did not change. Additionally, pSTAT3 increased by erlotinib was suppressed by JSI-124 both in the PC-9 and PC-9/ER3 cells. pAKT expressions treated by erlotinib with or without JSI-124 seemed to be equivalent in the PC-9 cells; however, the combination of erlotinib with JSI-124 more suppressed pAKT compared to erlotinib alone in the PC-9/ER3 cells.
Our results would suggest that the activation of JAK2/STAT3 signaling pathway followed by continuous erlotinib exposure accounts partly for the acquired resistance, and that it might be overcome by the combined treatment with JAK2 inhibitor.
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 717. doi:10.1158/1538-7445.AM2011-717
Abstract 72: Gene-specific H3K4 trimethylation changes in healthy human subjects exposed to carcinogenic metal components of air particles
Authors: Cantone Laura , Kluz Thomas , Tarantini Letizia , Bonzini Matteo , Marinelli Barbara , Bertazzi Pier Alberto , Baccarelli Andrea , Costa Max 
Published: June 2012

Abstract
Ambient and occupational exposure to air particulate matter (PM) has been consistently associated with increased risk of lung cancer. Epidemiological studies strongly indicate that the metal components of PM may be responsible for PM carcinogenicity, but the underlining mechanisms are poorly understood.
H3K4 trimethylation (H3K4me3) is known to be modified by exposure to carcinogenic metals in-vitro and correlates with transcriptional activation when found in gene promoter regions.
In a pilot study on workers of a steel-plant production, we investigated whether PM metal components, such as nickel and arsenic, had an effect on H3K4me3 in the promoter regions of target genes, including tumor suppressors and genes whose expression is increased following metal exposures, such as NIMA-related kinase 6 (NEK6) genes and carbonic anhydrase IX (CA9).
We obtained blood samples on the first (sample 1) and last (sample 2) day of a working-week from 10 subjects. We used gene-specific analysis by chromatin immunoprecipitation (ChIP)-real-time PCR in blood leukocytes to investigate whether H3K4 trimethylation changes, at different levels of exposure to airborne metals in PM, can influence transcription of CA9 and NEK6 genes.
We found that both for CA9 and NEK6, there was a difference between sample 1 and sample 2 in all subjects, with a higher level in sample 2; furthermore, in sample 2, we found a positive trend for H3K4me3 in CA9 and NEK6 genes with increasing levels of exposure to metals in PM compared to one unexposed control. The observed tendency is consistent with the fact that carcinogenic metals alter patterns of gene expression leading to activation of genes that may be relevant to the carcinogenic process.
These findings indicate that different levels of exposure to PM metal components can induce changes in H3K4 trimethylation that up-regulates transcription of CA9 and NEK6 genes.
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 72. doi:10.1158/1538-7445.AM2011-72
Abstract 73: PELP1 is a novel reader of chromatin modifications: Implications in cancer progression
Authors: Vadlamudi Ratna K. , Mann Monica , Cortez Valerie A. 
Published: June 2012

Abstract
Cancer is caused by abnormalities of the genome and epigenome including the frequently occurring epigenetic changes of histone modifications. Specifically, estrogen-induced breast carcinogenesis is characterized by alterations in histone modifications. Reader proteins that recognize these modifications facilitate modulation of genes and their resulting biological actions. In addition to regulation by several coregulators, estrogen receptor alpha (ERα) transcriptional activation or repression depends on the modulation of histone methylation at target promoters. The ERα coregulator PELP1 plays an important role in ERα signaling, is a proto-oncogene with aberrant expression in hormone-related cancers and a prognostic indicator of decreased survival in breast cancer patients. The molecular mechanisms by which PEPL1 promotes oncogenesis remain unknown; however, previous studies from our lab have shown that PELP1 interacts with histones and is a novel reader of chromatin modifications. To explore the PELP1 epigenetic interactome, we used a histone peptide array containing 384 unique combinations of histone modifications including methylation, phosphorylation, acetylation and citrullination. Our results show that PELP1 uniquely recognizes histones modified by arginine dimethylation, arginine citrullination and lysine dimethylation. Phosphorylation of residues adjacent to a methyl modification affects the ability of PELP1 to recognize histone methylation. Using various deletions of PELP1 peptides, we have found that PELP1 acts as a module for recognition of a specific histone modification through the carboxyl-terminal glutamic acid rich region. Reporter gene assays showed that PELP1 functionally interacts with arginine methyltransferases including CARM1 and PRMT6, both shown to be dysregulated in human cancers, and synergistically enhances ERα-transactivation. Chromatin immunoprecipitation assays revealed that PELP1 has the potential to alter histone H3 arginine methylation status at ERα target gene promoters. The critical role of PELP1 status in modulating arginine methylation status was also observed through in vivo studies which show PELP1 knockdown results in decreased tumorigenesis and arginine dimethylation. Our findings suggest that PELP1 is a reader of histone methyl modifications and deregulation may have implications on tumor proliferation via epigenetic alterations at ERα target promoters. Targeting these epigenetic alterations through inhibition of PELP1 and the arginine methyltransferases could be a promising cancer therapeutic. This study was funded by NIH grant CA095681.
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 73. doi:10.1158/1538-7445.AM2011-73
Abstract 730: Identifying the mechanisms of action and resistance to the novel multi-kinase inhibitor ENMD-2076 in leukemia
Authors: Failes Timothy , Mitic Gorjana , Kavallaris Maria 
Published: June 2012

Abstract
Background: Molecularly targeted agents such as kinase inhibitors have offered great promise in treatment regimens for cancer. However, the rapid development of resistance to kinase inhibitors mediated through adaptations such as point mutations in the target kinase domain has emerged as a major clinical problem. Accordingly, multi-kinase inhibitors are a promising class of chemotherapeutic agents that can target multiple cytotoxic pathways and potentially be less susceptible to the onset of resistance. ENMD-2076 is a multi-kinase inhibitor that targets Aurora A and multiple receptor tyrosine kinases involved in angiogenesis. ENMD-2076 is showing much promise in Phase I/II clinical trials, yet the specific pathways of sensitivity and resistance are still unclear.
Methods: Acute T-cell leukemia CCRF-CEM cells were selected for resistance in 6 µM of ENMD-2076. The resultant resistant cells were designated CEM/AKA6. The level of resistance to the selecting agent was characterized using drug treated cell viability assays. Screening for mutations in Aurora A was conducted using full-length gene sequencing. Real time PCR was used for gene and western blotting for protein expression studies. Phosphoprotein analysis was conducted using Full Moon Biosystems Inc, antibody arrays.
Results: CEM/AKA6 cells were 10-fold resistant to ENMD-2076. No significant changes in the gene and protein expression of Aurora A were found compared to the parental cells. Moreover, full-length sequencing of the Aurora A or Aurora B gene failed to detect mutations. CEM/AKA6 cells were as equally sensitive to a specific Aurora A inhibitor, MLN8237, as the parental cells, further suggesting that resistance to ENMD-2076 is not mediated through an Aurora A dependent pathway. ENMD-2076 is known to target the anti-apoptotic PI3K/Akt signaling pathway and CCRF-CEM cells have a deletion in PTEN that leads to constitutive activation of this pathway. Analysis of the Akt pathway using phospho-specific antibody arrays showed that phosphorylation of PDK1, upstream from Akt, was enhanced in CEM/AKA6 cells compared to parental cells, whilst phosphorylation of proteins downstream from Akt such as p53 and c-Jun was decreased. Validation, localization and functional characterization of these protein changes are planned.
Conclusions: The PI3K/Akt signaling pathway is altered in leukemia cells resistant to the multikinase inhibitor ENMD-2076. Understanding the interplay of this specific pathway in mediating resistance and/or sensitivity to ENMD-2076 will shed light on the mechanism of this promising agent and may enable optimization of its clinical use.
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 730. doi:10.1158/1538-7445.AM2011-730
Abstract 731: Nuclear factor-κB activation and cetuximab-resistance in HNSCC cell lines
Authors: Hatakeyama Hiromitsu , Dahlman Kimberly Brown , Su Zengliu , Robbert Slebos , Pao William , Chung Christine H. 
Published: June 2012

Abstract
Background: Cetuximab, a monoclonal antibody targeting EGFR, has been shown to increase survival in patients with head and neck squamous cell carcinoma (HNSCC). However, only selective patients gain therapeutic benefit. To determine a mechanism of primary resistance to cetuximab, we characterized a primary keratinocyte cell line and 34 HNSCC cell lines for somatic mutations and gene expression alterations.
Experimental design: Thirty-five cell lines were assessed by 1) multiplex SNaPshot genotyping to detect 38 somatic mutations in the EGFR and its related pathways, 2) DNA sequencing of the tyrosine kinase domains of MET and FGFR3 to detect mutations, 3) qRT-PCR to quantify EGFR, MET and FGFR1 gene copy number (CN), 4) microarray analyses for gene expression profiles, and 5) matrigel colony formation assays to determine sensitivity to cetuximab. Gene mutations and CN changes were examined for potential association with cetuximab sensitivity. Differentially expressed genes between the cetuximab-resistant and -sensitive cell lines were assessed by GeneSpring and Ingenuity Pathways Analysis (IPA). To confirm the expression array data, seven representative cell lines were treated with BAY-11-7082, an IKB kinase inhibitor, to inhibit NF-kB activity.
Results: Three of 35 cell lines had mutations in PIK3CA (E542K, E545Q and H1047R). The cell line with E542K mutation was resistant to cetuximab while the cell lines with E545Q and H1047R were sensitive to cetuximab. No mutations were found in MET or FGFR3. CN gains were detected in EGFR and FGFR1 (20 cell lines with EGFR CN 4-10, 10 with EGFR CN &gt;10, and 9 with FGFR1 CN 4-10), but not in MET. Interestingly, many of the cell lines with EGFR CN gains also had FGFR1 CN gains (Spearman rank test, r=0.48, p=0.0032). However, there was no correlation with the CN gains and cetuximab sensitivity. IPA showed genes involved in epithelial-to-mesenchymal transition (EMT) and NF-kB activation to be associated with cetuximab resistance. Cetuximab-resistant cell lines had higher expression of vimentin and lower expression of E-cadherin. BAY-11-7082 inhibited cellular proliferation of four cetuximab-resistant cell lines, but not three sensitive cell lines.
Conclusion: Mutations commonly seen in non-HNSCC cancers are rare, but EGFR and FGFR1 CN gains are common in HNSCC cell lines. The EMT phenotype and NF-kB activation may have an important role in cetuximab resistance and in novel therapeutic development in HNSCC.
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 731. doi:10.1158/1538-7445.AM2011-731