bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 5301: Rescuing cell polarity with small molecule inhibitors of de-palmitoylation
Authors: Hernandez Jeannie L. , Davda Dahvid , Majmudar Jaimeen , Labby Kristin J. , Gang Margery , Pasupuleti Sirisha , Seita Makoto , Martin Brent R.
Published: May 2015

Protein palmitoylation is a unique post-translational modification required for the membrane anchoring and trafficking of numerous regulatory proteins that play key roles in cell growth, polarity, and signaling. Using a pulse-chase palmitoylation proteomics approach, we identified the tumor suppressor Scrib as the most dynamic, enzymatically regulated palmitoylated protein in malignant cells. Scrib localizes at the basolateral membrane where it regulates epithelial cell apical-basolateral polarity, junctional integrity, proliferation, and metastasis. Loss of Scrib at the plasma membrane cooperates with oncogenic Ras or Myc overexpression to drive tumor formation, promote epidermal to mesenchymal transition (EMT), and bypass contact inhibition. Interestingly, overexpression of Snail in polarized cells eliminates Scrib membrane localization. We recently reported a class of in vivo active small selective inhibitors of the acyl protein thioesterases APT1 and APT2. Addition of a small molecule APT2 inhibitor restores Scrib membrane localization and enhances E-Cadherin expression, overcoming Snail-mediated repression of E-cad. These findings suggest that thioesterases, predominantly APT2 more than APT1, regulate the palmitoylation of cell polarity proteins, and highlight a strategy to attenuate oncogenic signaling and restore cell polarity pathways in malignant cells.

Citation Format: Jeannie L. Hernandez, Dahvid Davda, Jaimeen Majmudar, Kristin J. Labby, Margery Gang, Sirisha Pasupuleti, Makoto Seita, Brent R. Martin. Rescuing cell polarity with small molecule inhibitors of de-palmitoylation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5301. doi:10.1158/1538-7445.AM2014-5301
Abstract 5302: CITED2 as a molecular switch for hypoxia-mediated proliferation
Authors: Wang Yuan-Hung , Kuo Ming-Han , Huang Chien-Fu , Hsiao Shih-Hsin , Wu Cheng-Wen , Chou Yu-Ting
Published: May 2015

Hypoxia, the reduction of oxygen levels in cells or tissues, elicits a set of genes to adjust physiological and pathological demands during normal development and cancer progression. Hypoxia-mediated stabilization of hypoxia-inducible factor (HIF) 1α and 2α contributes to transcriptional regulation of genes involved in hypoxia-mediated physiological adaptation. Till now, the molecular mechanism of how HIF1α and HIF2α signaling regulates cancer cell proliferation and quiescence in hypoxic microenvironment is little understood. Here, we reported that CITED2, a cytokine inducible transcriptional modulator, is induced by HIF2α to regulate cell proliferation and quiescence. We observed that HIF2α expression is induced by hypoxia in a subgroup of lung cancer cells, proliferation of which is regulated via HIF2α/CITED2 signaling. Interestingly, HIF1α-silencing promotes hypoxic-mediated cell proliferation in the HIF2α-positive lung cancer cells. In contrast, knockdown of HIF2α as well as CITED2 attenuates cell growth, suggesting that HIF2α/CITED2 signaling functions as a molecular switch for cell proliferation and quiescence. Soft-agar assay showed that HIF2α promotes anchorage-independent growth of cancer cells, which can be inhibited by CITED2-silencing. We observed that upon hypoxia induction, CITED2 enhances MYC-mediated transactivation of downstream target genes. Our findings provide a novel oncogenic role of CITED2 in hypoxia with potential as a biomarker and therapeutic targets for lung cancer.

Citation Format: Yuan-Hung Wang, Ming-Han Kuo, Chien-Fu Huang, Shih-Hsin Hsiao, Cheng-Wen Wu, Yu-Ting Chou. CITED2 as a molecular switch for hypoxia-mediated proliferation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5302. doi:10.1158/1538-7445.AM2014-5302
Abstract 5308: A proteome analysis of the cadmium response in human bronchial epithelial cells: Identification of potential biomarkers related to cadmium exposure
Authors: Lau Andy T. Y. , Chen De-Ju , Du Ji-Ying , Xu Yan-Ming
Published: May 2015

Cadmium (Cd) and Cd derivatives are ubiquitously-distributed in the living environment. In particular, the contamination of Cd in the food chain, occupational exposure and tobacco smoke provide important sources of human exposure to Cd. Here, we provide a proteomic analysis of human bronchial epithelial cells (BEAS-2B) treated with CdCl2, with the aim of identifying protein response to Cd toxicity. Comparative proteome analysis was conducted at the intracellular (cell lysate) and extracellular (spent medium) levels to identify global changes in the protein expression profiles of sham-exposed and Cd-treated cells. Proteins were separated by two-dimensional electrophoresis and visualized by silver staining. We reported that while a low level (2 μM) of Cd treatment for 36 h elicited negligible cytotoxicity and produced no significant proteome changes between the treated group and the control, however, high levels (20 or 30 μM) of Cd treatment for 36 h induced obvious proteome changes and cell death in BEAS-2B cells. Differentially-expressed proteins were identified by LC-MS/MS and further confirmed by Western blot analysis. The proteins that were significantly up-regulated included molecular chaperones (e.g. HSP90B1, HSPA6, TCP-1-epsilon), antioxidative stress enzymes (e.g. GST-P1 and -O1, thioredoxin, peroxiredoxin-1 and -2), as well as pro-apoptotic proteins (e.g. GAPDH, eIF-5A-1). Interestingly, we also found that the redox-sensitive transcription factor NF-κB is up-regulated; while the tumor suppressor p53 is significantly down-regulated by high levels of Cd treatment. Pretreatment with the thiol antioxidant glutathione before Cd treatment effectively abrogated the up-regulation or down-regulation of these marker proteins and prevented cell death. Taken together, our results demonstrate that high levels of Cd cause oxidative stress-induced cytotoxicity, while a low level of Cd may exert a more noticeable effect after long-term exposure, but not after transient exposure.

Citation Format: Andy T. Y. Lau, De-Ju Chen, Ji-Ying Du, Yan-Ming Xu. A proteome analysis of the cadmium response in human bronchial epithelial cells: Identification of potential biomarkers related to cadmium exposure. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5308. doi:10.1158/1538-7445.AM2014-5308
Abstract 5317: Photonic crystal microarray sensing of breast cancer cell line lysates
Authors: Chakravarty Swapnajit , Tang Naimei , Yan Hai , Yang Chun-ju , Zou Yi , Shen Qiang , Chen Ray
Published: May 2015

Monitoring of protein expression changes in cells or in real tissue is commonly based on western blot and protein microarray. However, these assays have limitations that include lack of detection sensitivity and accuracy. Furthermore, fluorescent, radioactive or magnetic tags or labels are typically needed for signal transduction, which may not always be preferable, as more and more new markers are being discovered. In this study, we have used our silicon chip based label free high throughput high sensitivity XtremeSens Diagnostics benchtop nanophotonic platform to detect the target proteins that are regulated by TAM67. The platform has currently demonstrated the smallest sensor on chip with the highest sensitivity down to 67femtograms per milliliter with specificity. The target proteins were selected based on western blot results which shows that when Tam67 is overexpressed in MCF-7 Tam67 clone cells, PCNA is up-regulated; ß-catenin, cyclinD1, p-EGFR expression are down-regulated, and E-cadherin seems to have no change. The probe antibodies were printed on unique photonic crystal microcavities and cell lysates were detected by a label-free method.

The assay is based on the highly sensitive photonic crystal platform in silicon-on-insulator chips in which light-matter interaction is enhanced due to confinement and guiding of light on length scales of the wavelength of light. The probe proteins are immobilized on unique photonic crystal microcavities in the array. All sensors are exposed to the analyte at the same instant of time. The binding interaction alters the refractive index of the resonance cavity and this is detected as a shift in the resonance wavelength trapped by the device. The resonance shift is detected directly and does not require any secondary labeling. Specificity is demonstrated using a sandwich assay in which a second antibody was introduced following the initial binding and washing steps and a secondary resonance wavelength shift is observed.

The impact of this study will provide the wide range of applications including the study of cancer biomarker, signal transfection pathway, clinical diagnosis of diseases, commercialization potential is envisioned in other civilian markets such as environmental pollution sensing, food pathogen detection and biodefense.

Citation Format: Swapnajit Chakravarty, Naimei Tang, Hai Yan, Chun-ju Yang, Yi Zou, Qiang Shen, Ray Chen. Photonic crystal microarray sensing of breast cancer cell line lysates. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5317. doi:10.1158/1538-7445.AM2014-5317
Abstract 532: Evaluation of the role of miRNA-4728-3p, a miRNA located in an intron of HER2 gene, in breast cancer stem cells
Authors: Carneiro Juliana Laino do Val , Nunes Diana Noronha , Dias-Neto Emmanuel
Published: May 2015

Background: Cancer stem cells (CSCs) contribute to tumor metastasis, chemotherapy resistance, and are highly tumorigenic when injected into immunodeficient mice. High levels of aldehyde dehydrogenase (ALDH1) are characteristic of stem cells and allow the isolation of subpopulations of CSCs, including those derived from breast cancer. HER2+ tumors, which are more aggressive than tumors with no amplification of this oncogene, are enriched in CSCs, a finding that suggests the participation of this oncogene in the generation and maintenance of CSCs. miR-4728-3p is a poorly investigated miRNA, which is located inside an intron of HER2. Its expression is increased in HER2+ tumors and cell lines, but its role in CSC formation and tumor behavior has not been investigated. Aim: to contribute to the better understanding of the role of miRNA-4728-3p in the biology of CSCs in HER2+ breast cancer cell lines. Methods: miR-4728-3p levels were evaluated in breast cancer cell lines MCF-7, BT-474 and SKBR3 grown in adherent conditions and in conditions that favor the formation of mammospheres for 7, 14, 21 and 28 days. Overexpression of miR-4728-3p was performed using lentiviral transduction with plasmids for the overexpression of this miRNA. Flow cytometry was performed to analyze ALDH1 expression in adherent cells and cells derived from mammospheres and also in cells overexpressing miRNA-4728-3p. Results: Mammospheres in culture for 7 days showed high levels of ALDH1 for all cells lines evaluated. The overexpression of miR-4728-3p induced a significant increment (>10-fold) of ALDH1+ subpopulations in MCF-7 and SKBR3, reinforcing its possible role in the biology of CSCs. Conclusion: HER2-amplification is an event that intrinsically leads to the amplification of miR-4728-3p. The effects of the amplification of this oncogene and this miRNA have to be evaluated together as both may have important consequences for tumor behavior and CSC formation. This increased expression of ALDH1 after miR-4728-3p overexpression suggest the importance of this miRNA in the biology of CSC formation.

Note: This abstract was not presented at the meeting.

Citation Format: Juliana Laino do Val Carneiro, Diana Noronha Nunes, Emmanuel Dias-Neto. Evaluation of the role of miRNA-4728-3p, a miRNA located in an intron of HER2 gene, in breast cancer stem cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 532. doi:10.1158/1538-7445.AM2014-532
Abstract 5336: Mathematical models for cellular response to radiochemotherapy
Authors: Williams Katherine S. , El-Kareh Ardith W. , Secomb Timothy W.
Published: May 2015

To optimize radiochemotherapy, several clinically adjustable factors must be considered: sequence order (drug administered before, during, or after radiation exposure); time interval between the agents; dose of each agent; and fractionation. Because the combined effects of all these factors are complex, mathematical modeling can provide a useful framework for discerning the role of each individual factor and can be applied to predict response to future experimental protocols. To date, there has been scant effort devoted to mathematical models for cellular response to radiochemotherapy. One widely-used model is based on the assumption that the two modalities act completely independently; the total cell survival fraction is the product of survival fractions for each agent acting alone. However, an examination of a number of dose-response data sets for paclitaxel followed by radiation exposure shows that the independent cell kill model consistently underestimates cell kill. The additive damage model, which is based on the assumption that cell kill depends on a quantity called cellular damage, is constructed as the sum of terms from each agent and is shown to better describe some data sets for ascorbate and paclitaxel. Cellular dose-response data sets for radiochemotherapy have shown complex interactions between therapies, with strong dose-dependent antagonism in some cases, and significant, non-monotonic dependence on the time interval between the modalities in others. We present generalizations of the additive damage model, which include either dose-dependent cell-cycle blocking or transport kinetics, and show that they can describe some of these experimentally-observed complex behaviors. In conclusion, the generalized additive damage model is a promising tool to describe cellular pharmacodynamics of radiochemotherapy and is expected to have application to the optimization of dosage and schedule.

Citation Format: Katherine S. Williams, Ardith W. El-Kareh, Timothy W. Secomb. Mathematical models for cellular response to radiochemotherapy. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5336. doi:10.1158/1538-7445.AM2014-5336
Abstract 5337: Molecular dynamics study on keap1 point mutations in lung cancer
Authors: Yang Chia-Ning
Published: May 2015

Keap1 is a BTB-Kelch substrate adaptor protein that regulates steady-state levels of Nrf2, a bZIP transcription factor, in response to oxidative stress. In basal condition, Nrf2 is negatively regulated through ubiquitination by Keap1. However, upon exposure to oxidative stress, ubiquitination of Nrf2 is inhibited, resulting increased steady-state level of Nrf2 and increased transcription of cytoprotective ARE (antioxidant response elements)-dependent genes. Reported in 2006, the structure of Keap1 Kelch domain in complex with a 16-mer peptide derived from Nrf2 has been solved by X-ray crystallography to a resolution of 1.85Å. Accordingly, it grants us a chance to evaluate the interaction between Keap1 and Nrf2 and further interpret numerous experimental findings on unbinding due to modifications on Keap1. Herein we apply molecular dynamics simulations to study the binding behaviors of Keap1 and Nrf2 based on the solved structure to investigate how single point mutations G364C and G430C on Keap1 affect Keap1-Nrf2 binding and further cause lung cancer.

Note: This abstract was not presented at the meeting.

Citation Format: Chia-Ning Yang. Molecular dynamics study on keap1 point mutations in lung cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5337. doi:10.1158/1538-7445.AM2014-5337
Abstract 534: MicroRNA-143 is a putative predictive biomarker for 5-FU-based chemotherapy in patients with metastatic colorectal cancer
Authors: Simmer Femke , Dijkstra Jeroen , Venderbosch Sabine , Faber Claudius , Mekenkamp Leonie , Koopman Miriam , Haan Ton de , Punt Cornelis , Nagtegaal Iris
Published: May 2015

Background: Approximately half of the colorectal cancer (CRC) patients develop metastatic disease, either at diagnosis or during follow-up. 5-FU-based chemotherapy forms the backbone of treatment in these patients. However, the response to this therapy varies between individuals. Therefore, an important challenge in CRC research is to identify biomarkers that are predictive of this response.

MicroRNAs are short RNAs that post-transcriptionally regulate the gene expression of many genes. MicroRNA levels are frequently altered in cancer, and can affect expression of genes that modulate tumorigenesis.

Objective: In this study, we explore the potential of microRNAs, and the microRNA producing protein Dicer, as biomarkers that can predict chemo-sensitivity in patients with metastatic colorectal cancer.

Methods: We analyzed the levels of a selected panel of 22 miRNAs and the Dicer protein in primary CRC tumors from patients enrolled in the CAIRO study (a phase III study of the Dutch Colorectal Cancer Group). MiRNA levels were determined with Taqman microRNA assays and Dicer level with immunohistochemistry. Correlation between the expression status of microRNAs or Dicer in primary tumors and the progression free survival (PFS) were investigated. In addition, we evaluated correlations between Dicer and miRNA levels.

Results: Variable Dicer intensities were observed among the analyzed samples, but there was no significant association between Dicer levels and PFS. In addition, no clear correlation between Dicer and miRNA levels could be identified. We especially detected higher expression of miR-31 and miR-21 in tumors compared to matched normal tissue, whereas miR-137 and miR-215 were lower expressed. Interestingly, miR-143 expression was reduced in a subset of the primary CRC tumors, and this differential expression showed a relationship with PFS. The group with reduced miR-143 expression showed higher PFS. The median PFS for patients with reduced, neutral and increased miR-143 expression was 261, 167 and 142 days, respectively (p-value log-rank test=0.018).

Conclusion: The expression level of miR-143 may have clinical utility as a biomarker for response to 5-FU-based chemotherapy. These findings warrant further studies to investigate the relationship between miR-143 expression and 5-FU.

Citation Format: Femke Simmer, Jeroen Dijkstra, Sabine Venderbosch, Claudius Faber, Leonie Mekenkamp, Miriam Koopman, Ton de Haan, Cornelis Punt, Iris Nagtegaal. MicroRNA-143 is a putative predictive biomarker for 5-FU-based chemotherapy in patients with metastatic colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 534. doi:10.1158/1538-7445.AM2014-534
Abstract 5344: Rapid induction and progression of PhIP+DSS-induced colon carcinogenesis in CYP1A-humanized mice
Authors: Chen Jayson X. , Wang Hong , Li Guangxun , Liu Anna , Yang Chung S.
Published: May 2015

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), the most abundant heterocyclic amine generated from high temperature cooking of meat and fish, is metabolically activated by human cytochrome P450 (CYP)1A2 to a proximate carcinogen. Using CYP1A-humanized (hCYP1A) mice, previous study in our lab demonstrated that a single i.g. administration of PhIP (200mg/kg b.w.), followed by 1.5% Dextran Sodium Sulfate (DSS) in drinking water for 7 days, can rapidly induce tumors in the colon with 100% incidence. Multiple adenocarcinomas were observed with elevation of β-catenin, a key protein in the Wnt signaling pathway, as well as iNOS, COX-2, cyclin D1 and c-Myc. In the present study, we investigated the early stage colon carcinogenesis in the hCYP1A mice treated with PhIP (2x 100mg/kg b.w.) and DSS (4 days). After 4 days of DSS treatment, clinical manifestation such as weight loss, diarrhea, and bloody stools were observed. At day 1 after DSS cessation, we found severe damages to the colon epithelium with expansive crypt degeneration, ulcerations and inflammation. At days 3 and 7, we detected epithelial hyperplasia and dysplasia in addition to extensive ulcerations and inflammation. At days 11 and 17, we identified early adenoma and adenocarcinoma, respectively. Similar adenomatous lesions were not observed in hCYP1A mice treated with only DSS. Using immunohistochemistry, we detected strong nuclear staining of β-catenin, specifically within the early adenomas and adenocarcinomas. Further examination using Ki67 marker revealed strong nuclear staining in the adenomas and adenocarcinomas as well as areas of hyperplasia and dysplasia, indicating their high level of proliferation and generation. DNA sequencing revealed 96% of the PhIP+DSS induced colon tumors at week 10 carried a β-catenin mutation, particularly in the codon 32, 33, and 34. Altogether, we demonstrate the rapid induction and progression of colon tumorigenesis in hCYP1A mice, initiated by PhIP-induced Wnt dysregulation and promoted by DSS-induced colitis. (Supported by NIH grants F31CA168333, RO1CA120915 and RO1CA133021 as well as shared facilities funded by CA72720 and ES05022)

Citation Format: Jayson X. Chen, Hong Wang, Guangxun Li, Anna Liu, Chung S. Yang. Rapid induction and progression of PhIP+DSS-induced colon carcinogenesis in CYP1A-humanized mice. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5344. doi:10.1158/1538-7445.AM2014-5344
Abstract 5353: Leptin regulates cell differentiation and protumorigenic responses in pancreatic stellate cells
Authors: Gong Jun , Gong Raymond , Waldron Richard T. , Lugea Aurelia , Pandol Stephen J.
Published: May 2015

Pancreatic ductal adenocarcinoma (PDAC) is characterized by marked desmoplasia orchestrated by pancreatic stellate cells (PaSCs). Epidemiological studies indicate that obesity and chronic pancreatitis (from alcoholism) increase the risk of PDAC. We recently showed that a diet high in fats and calories increases blood leptin levels and accelerates the development of desmoplasia and early pancreatic neoplasia in the conditional KrasG12D mouse model of pancreatic carcinogenesis. We hypothesize that environmental risk factors such as obesity and alcohol abuse facilitate PDAC progression by regulating PaSC tumorigenic responses. Here we measured leptin and ethanol effects on cell differentiation into the myofibroblast phenotype, cell proliferation and fibrogenic responses in primary mouse PaSC and mouse and human PaSC lines. Inhibitors of mTOR signaling were used to delineate the role of mTOR on leptin-mediated PaSC responses. We found that leptin receptors are expressed in cultured-activated primary mouse PaSCs and in immortalized mouse and human PaSCs. In quiescent PaSCs isolated from the mouse pancreas, leptin alone or in combination with ethanol markedly accelerated PaSC activation and promoted extracellular matrix (ECM) protein production (collagen and fibronectin) via ERK and Akt/mTORC1 signaling pathways, suggesting that these pathways interact to modulate the activated PaSC phenotype. In activated PaSCs, leptin induced activation of JAK/STAT and mTORC1 signaling pathways, and the mTORC1 inhibitor rapamycin blocked leptin-induced mTORC1 activation and markedly reduced fibronectin production and cell proliferation. Other factors known to regulate cell proliferation and inflammation in obesity and alcohol abuse, such as IGF-1, TNFα, and LPS also transiently activated Akt/mTORC1 signaling in PaSCs. Further, we found that pancreatic intraepithelial neoplasia (PanIN) cells isolated from the KrasG12D mice interact with PaSCs to promote their proliferation and ECM production. Our data support a key role for leptin-induced Akt/mTOR signaling in regulating PaSC pro-tumorigenic responses and indicate that leptin and other inflammatory factors provide the mechanistic underpinnings of environmental risk factor promotion in PDAC.

Citation Format: Jun Gong, Raymond Gong, Richard T. Waldron, Aurelia Lugea, Stephen J. Pandol. Leptin regulates cell differentiation and protumorigenic responses in pancreatic stellate cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5353. doi:10.1158/1538-7445.AM2014-5353
Abstract 5361: Development of targeted inhibitors against RecQ1 helicase
Authors: Zuo Mingxin , Maxwell David , Prasad Basvoju A. Bhanu , Peng Zhenghong , Bornmann William , Javle Milind M.
Published: May 2015

Background: RecQ helicases are a ubiquitous family of DNA unwinding enzymes involved in the maintenance of chromosome stability. RecQ1 helicase genomic variations have an important prognostic role and represents a therapeutic target in pancreatic cancer [JCO 2006; 24 (11) 1720-1728]. Pubchem data indicated potential RecQ1 activity >600 compounds using a qHTS RecQ1 assay (NIH Chemical Genomics Center).

Methods: We applied a set of filters including molecular weight, potency and Hill curve fitting and also removed those interfering with biological assay to identify sixteen compounds for studying RecQ1 inhibition. Two compounds showed strong inhibition of RecQ1 helicase activity at 50 µM and at IC50 < 5 µM, respectively. From a large library of compounds, eight potential inhibitors were synthesized in three simple steps. First, sulfonylation of various amines with 3-Nitrobenzenesulfonyl chloride was performed followed by reduction of the nitro group into an amine. Finally, acylation with variety of acid chlorides resulted in the final library of RecQ1 analogs. These agents were studied for RecQ1 helicase activity assay with the radiolabeled partial duplex substrate in vitro. The RecQ1 inhibitor candidate compounds were investigated in pancreatic cancer cell lines (AsPC-1, BxPC-3, Capan-1, PANC-1, and Mia-Paca2) for anti-tumor efficacy using cell proliferation assay with CellTiter-Glo® luminescence. Combination studies with test compounds and poly (ADP ribose) polymerase (PARP) inhibitor olaparib and topoisomerase Inhibitor SN38 were performed. Results: Though none of the compounds showed the same level of activity of the parent compounds, we were able to demonstrate a modest level of helicase activity with several. Two compounds displayed strong inhibition of pancreatic cancer cell proliferation. Two other compounds displayed synergistic inhibition with SN38 or olaparib of pancreatic cancer cell proliferation and induced DNA damage.

Conclusions: Synthesis of RecQ1 inhibitors is feasible and shows potential for anti-tumor efficacy.

Note: This abstract was not presented at the meeting.

Citation Format: Mingxin Zuo, David Maxwell, Basvoju A. Bhanu Prasad, Zhenghong Peng, William Bornmann, Milind M. Javle. Development of targeted inhibitors against RecQ1 helicase. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5361. doi:10.1158/1538-7445.AM2014-5361
Abstract 5362: Deficiencies in mismatch repair proteins induce elevated levels of acrolein-derived 1,N2-propanodeoxyguanosine and apoptosis in human colon cancer cells treated with acrolein
Authors: Pan Jishen , Xuan Zhuoli , Dyba Marcin , Zhang Yongwei , Fu Ying , Roy Rabindra , Weiner Louis M. , Chung Fung-Lung
Published: May 2015

Acrolein-derived 1,N2-propanodeoxyguanosine (Acr-dG) is a ubiquitous DNA modification in vivo that may play a role in carcinogenesis. It can be formed when DNA reacts with acrolein in environmental pollutants, such as cigarette smoking and oil combustion, and from endogenous source through oxidation of polyunsaturated fatty acids (PUFAs). We have previously demonstrated that the formation of Acr-dG at a threshold level is linked to apoptosis in cells treated with PUFAs under oxidative condition, suggesting a potential role of Acr-dG in the apoptosis induced by PUFAs, especially ω-3 PUFAs. Acr-dG can be repaired by the nucleotide excision repair (NER) pathway. To examine whether mismatch repair (MMR) pathway is also involved in the repair of Acr-dG, we treated MLH1-deficient HCT116 cell and its isogenic MLH1-proficient HCT116+ch3 cell with acrolein. The Acr-dG levels and apoptosis both were higher in HCT116 cells compared to HCT116+ch3 cells. To further study the role of MMR proteins in the repair of Acr-dG, either MLH1 or MSH2 was knocked down in HCT116+ch3 cells. The results showed that the levels of Acr-dG and apoptosis induction were both significantly higher in the knockdown cells than the cells transfected with control siRNA. The levels of p-ATM and γ-H2AX were also increased to a greater extent in HCT116 cells than HCT116+ch3 cells, and in the MLH1 and MSH2 knockdown cells than the control cells when treated with acrolein at the doses that induce higher levels of Acr-dG. This study shows that MMR proteins, MLH1 and MSH2, are involved in the repair of Acr-dG. The results also suggest that Acr-dG may cause double-strand breaks which lead to apoptosis. Whether MMR acts as an independent repair pathway for Acr-dG or MMR proteins cross-talk and interact with other DNA repair pathways, such as NER, is under investigation. (Supported by NCI grant CA43159)

Citation Format: Jishen Pan, Zhuoli Xuan, Marcin Dyba, Yongwei Zhang, Ying Fu, Rabindra Roy, Louis M. Weiner, Fung-Lung Chung. Deficiencies in mismatch repair proteins induce elevated levels of acrolein-derived 1,N2-propanodeoxyguanosine and apoptosis in human colon cancer cells treated with acrolein. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5362. doi:10.1158/1538-7445.AM2014-5362
Abstract 5363: Genotoxicity of trace level of hexavalent chromium existing in city water
Authors: Tian Xu , Patel Keyur , Ridpath John R. , Swenberg James A. , Nakamura Jun
Published: May 2015

Tens of millions of Americans consume trace amounts of potentially toxic hexavalent chromium (Cr(VI)) through drinking city water every day. According to the studies conducted by the Environmental Working

Group, 89% of the water samples from U.S. cities are contaminated with Cr(VI) at levels ranging from 0.03 to 12.9 μg/L. While trivalent chromium (Cr(III)) is among the essential trace elements for normal carbohydrate, lipid, and protein metabolism in humans, Cr(VI) has been extensively studied as a toxic heavy metal ion. Cr(VI) is a well-known human carcinogen by inhalation; in contrast, it is a rodent carcinogen by ingestion of extremely high doses (57,300 μg/L or higher) in drinking water. The United States Environmental Protection Agency (USEPA) and other regulatory agencies in the world have set the maximum contaminant levels (MCL) for total Cr or Cr(VI) in human drinking water at 50 or 100 μg/L, although the USEPA is currently re-evaluating these regulations. The mechanism by which Cr(VI) causes genotoxicity is well-characterized at concentrations equivalent to current regulatory levels or higher. The genotoxic mode of action of Cr(VI) appears to be due to the intracellular reduction of Cr(VI) to Cr(III) leading to the formation of a ternary complex between DNA, Cr(III), and intracellular reducing molecules. However, little information is available regarding the biological effects of Cr(VI) at doses lower than 100 μg/L. In this study, we investigated the effects of Cr(VI) at nanomolar ranges (1 μg/L or higher) on the DNA damage response in isogenic cultured cells deficient in various DNA repair genes. Here we show that the DNA damage response is observed after a three-day incubation with Cr(VI) at 2-5 μg/L (ppb), which is lower than the Cr(VI) concentrations detected in some of city water in the US. Strikingly, the genotoxicity of Cr(VI) decreased ∼3000 times depending on its incubation time, ranging from three days to ten minutes. Our dose- and time-dependent Cr(VI) genotoxicity results, combined with the estimated transit time of Cr(VI) in the digestive tracts of humans, strongly suggest that trace amounts of Cr(VI) in drinking water at levels 12.9 μg/L or lower are unlikely to cause a significant impact on inducing carcinogenicity in the oral cavity and small intestine.

Citation Format: Xu Tian, Keyur Patel, John R. Ridpath, James A. Swenberg, Jun Nakamura. Genotoxicity of trace level of hexavalent chromium existing in city water. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5363. doi:10.1158/1538-7445.AM2014-5363
Abstract 5364: ATF3 contributes to the DNA damage response by regulating the histone acetyltransferase Tip60
Authors: Cui Hongmei
Published: May 2015

Activating transcription factor 3 (ATF3) is a common stress mediator, and its expression is rapidly induced upon DNA damage. Although we have demonstrated that ATF3 can activate the tumor suppressor p53 and regulate expression of p53 target genes, the consequences of ATF3 induction by DNA damage remain elusive. Tat-interactive protein 60 (Tip60) belongs to the MYST family of histone acetyltransferase, and plays important roles in regulating chromatin remodeling, transcription, and the DNA damage response. While Tip60-mediated p53 acetylation promotes pro-apoptotic gene expression, Tip60 can also catalyze acetylation of ATM resulting in increased ATM kinase activity thereby mobilizing DNA repair machinery. Here we report that ATF3 can directly bind Tip60 and regulates its function in the DNA damage response. ATF3 binds Tip60 via its leucine zipper domain, and can increase Tip60 stability by blocking its ubiquitination. This effect is achieved through ATF3 binding to Tip60 as an ATF3 mutant devoid of Tip60 binding fails to block Tip60 ubiquitination and stabilize Tip60. Consistent with these results, knockdown of ATF3 expression decreases the level of Tip60 protein, but not its mRNA. Interestingly, ATM phosphorylation, a marker for ATM activation, is significantly suppressed in ATF3 knockdown cells. Therefore, we identified that ATF3 as a novel regulator of Tip60 in the DNA damage response. Our results suggest that, consistent with its tumor suppressor role, ATF3 may contribute to the DNA damage response by activating ATM signaling.

Citation Format: Hongmei Cui. ATF3 contributes to the DNA damage response by regulating the histone acetyltransferase Tip60. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5364. doi:10.1158/1538-7445.AM2014-5364
Abstract 5366: Mutation signature of TP53 gene in H. pylori-associated inflamed gastric mucosa during gastric carcinogenesis
Authors: Shimizu Takahiro , Marusawa Hiroyuki , Chiba Tsutomu
Published: May 2015

Helicobacter pylori (H. pylori) infection and the resultant chronic gastric inflammation is an important etiologic factor for gastric cancer development. To explore the genetic basis of gastric cancer that develops in inflamed gastric mucosa, we investigated genetic aberrations that latently accumulate in non-tumorous gastric epithelium with H. pylori infection. Whole exome sequencing on gastric cancer, non-cancerous gastritis tissues and peripheral lymphocytes of 5 patients revealed that somatic mutations accumulated in various genes in inflamed gastric tissues. Additional deep sequencing analyses of selected tumor-related genes in 34 gastritis mucosa samples from patients with, or without, gastric cancer revealed non-synonymous low-abundance mutations in TP53 in 15 cases (44.1%) and ARID1A in 5 cases (14.7%). The mutation signature of whole exome sequences in gastric cancer genomes as well as low-abundance TP53 mutations latently accumulated in H. pylori-inflamed gastritis mucosa were predominantly biased to C:G>T:A transitions in the context of GpCpX motifs, the typical footprints of cytidine deamination triggered by activation-induced cytidine deaminase (AID). In vivo studies with a human TP53 knock-in mouse model revealed that constitutive AID expression in the gastric mucosa caused the emergence of human TP53 mutations at the amino acid positions identical to those detected in human gastric cancers. These findings provide novel evidence that somatic mutations latently accumulated in various genes in inflamed gastric mucosa with H. pylori infection, and cytidine deaminase activity might provide a putative genetic basis for the increased susceptibility to gastric carcinogenesis in patients with H. pylori infection.

Citation Format: Takahiro Shimizu, Hiroyuki Marusawa, Tsutomu Chiba. Mutation signature of TP53 gene in H. pylori-associated inflamed gastric mucosa during gastric carcinogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5366. doi:10.1158/1538-7445.AM2014-5366
Abstract 5375: Enhanced permeability of nanoscale chemotherapeutic agents for the treatment of breast cancer
Authors: Molina Oliver , Yu Eugena , Abdulabbas Sarah , Lopez Steve
Published: May 2015

Nanotechnology is becoming increasingly successful in advancing site-specific drug delivery to cancer tissues. The ability to deliver drugs more effectively to a region of interest translates into less harmful side effects and more beneficial therapeutic action. This technology is currently in use in treating a number of human cancers. Certain therapeutic limitations are encountered, such as short circulation life, poor drug permeability, and drug resistance. These limitations can be addressed with the use of nanoscale particles that allow for controlled release of the drug. This presentation will educate the audience about approaches to treating cancer using new technologies.

Objectives

The main objective of this strategy is to minimize the side effects associated with chemotherapy, while enhancing the overall efficacy of the treatment of breast cancer, and other cancers.

- Tackle drug limitations by combining nanotechnology and chemotherapeutic methods that have been shown to increase therapeutic efficacy

- Measure the effects of this combinatorial strategy using a mouse model bearing human breast tumors

- Assemble the drug into a nanoscale shell in order to form a polymeric nanoparticle capable of providing controlled drug release.

- Create leaky vasculature in the vicinity of tumor tissue without affecting normal tissue

Methods

1st Method: Synthesis of a nanoparticle which encapsulates two chemotherapeutic agents, Paclitaxel and Cisplatin. The nanoparticle formed is a lipid-polymer hybrid whose main components are as follows: a core encapsulating the two drugs; a biocompatible shell to promote drug retention inside the core; and a polymer stealth layer outside the lipid shell to enhance nanoparticle stability and systemic circulation lifetime.

2nd Method: The tumor will be starved by limiting vascular growth using the drug, Endostatin. In addition, the permeability of the vasculature surrounding the tumor will be made more permeable for drug uptake by using a permability enhancing agent, iRGD.

Note: This abstract was not presented at the meeting.

Citation Format: Oliver Molina, Eugena Yu, Sarah Abdulabbas, Steve Lopez. Enhanced permeability of nanoscale chemotherapeutic agents for the treatment of breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5375. doi:10.1158/1538-7445.AM2014-5375
Abstract 5376: Systematic analysis of peptide linker length and liposomal polyethylene glycol coating on cellular uptake of peptide-targeted liposomal nanoparticles
Authors: Stefanick Jared , Ashley Jonathan , Kiziltepe Tanyel , Bilgicer Basar
Published: May 2015

In an effort to improve tumor targeting and cellular uptake of nanoparticle-based drug carriers, nanoparticles are functionalized with active targeting molecules such as antibodies, antibody fragments, small ligands, and peptides. However, active targeting approaches have not consistently shown successful outcomes. Nanoparticle design factors including: traditional methods of generating active targeting nanoparticles, PEG coatings, linkers used to conjugate targeting ligands, and various types of targeting ligands used further contribute to the inconsistencies observed with targeted nanoparticle therapies. In order to dissect the individual effects of these parameters, we employed a multifaceted synthetic strategy to prepare peptide-targeted liposomal nanoparticles with high purity, reproducibility, and precisely controlled stoichiometry of functionalities to evaluate the role of liposomal PEG coating, peptide EG-linker length, and peptide valency on cellular uptake in a systematic manner. We analyzed these parameters in two distinct disease models where the liposomes were functionalized with either HER2- or VLA-4-antagonistic peptides to target HER2-overexpressing breast cancer cells or VLA-4-overexpressing myeloma cells, respectively. When targeting peptides were tethered to nanoparticles with an EG45 (∼PEG2000) linker in a manner similar to a more traditional formulation, their cellular uptake was not enhanced compared to non-targeted versions regardless of the liposomal PEG coating used. Conversely, reduction of the liposomal PEG to PEG350 and the peptide linker to EG12 dramatically enhanced cellular uptake by ∼9-fold in breast cancer cells, while an EG6 peptide linker enhanced cellular uptake by ∼150-fold in multiple myeloma cells. Uptake efficiency is highly dependent on peptide valency, reaching a maximum and a plateau with ∼2% peptide density in the breast cancer model. Taken together, these results demonstrate the significance of using the right design elements such as the appropriate peptide EG-linker length in coordination with the appropriate liposomal PEG coating and optimal ligand density in efficient cellular uptake of liposomal nanoparticles.

Citation Format: Jared Stefanick, Jonathan Ashley, Tanyel Kiziltepe, Basar Bilgicer. Systematic analysis of peptide linker length and liposomal polyethylene glycol coating on cellular uptake of peptide-targeted liposomal nanoparticles. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5376. doi:10.1158/1538-7445.AM2014-5376
Abstract 5381: VLA-4 targeted nanoparticles deliver a cMYC-MAX prodrug antagonist extends survival a metastatic myeloma mouse model
Authors: Soodgupta Deepti , Pan Dipanjan , Cui Grace , Senpan Angana , Yang Xiaoxia , Wickline Samuel A. , Prochownik Edward V. , Weilbaecher Katherine N. , Tomasson Michael H. , Lanza Gregory M.
Published: May 2015

Background: While it is well known that MYC oncoprotein drives multiple myeloma (MM) pathogenesis, the development of several small-molecule inhibitors of the c-MYC/MAX interaction has been limited by rapid systemic metabolism, poor bioavailability and the inability of the drug to reach inhibitory concentrations in the tumor.

Objective: The goal of this study was to develop and deliver an effective VLA-4-targeted Sn 2 lipase-labile Myc-inhibitor nanotherapy.

Experimental Methods: A novel Sn 2 phosphatidylcholine-cMyc-Max antagonist prodrug (M1-PD) was designed, synthesized, characterized and evaluated in vitro and in vivo. In vitro, titrated free M1-PD was compared to free Myc-antagonist in human MM cell lines (H929 and U266) and mouse MM (5TGM1). M1-PD was incorporated into two lipid-based nanoparticle genera (<20nm and ∼200nm) that were functionalized for MM targeting using a peptidomimetic VLA-4-lipid ligand. The nanoparticles were physico-chemically characterized and evaluated for their relative pharmacokinetics in vivo. Effectiveness of the two VLA-4-targeted M1-PD nanotherapies were evaluated in MM cell cultures, correlated with VLA-4 expression levels, and then studied in C57BL/KaLwRij mice with metastatic 5TGM1.

Results: Bioactivity of free M1-PD was several orders magnitude more potent that the free cMyc antagonist in cell culture. Binding and efficacy of M1-PD nanoparticles correlated with integrin expression in target cells. VLA-4-M1-PD nanoparticles (<20nm and ∼200nm) equivalently inhibited MM cell growth in vitro compared to controls. In C57BL/KaLwRij mice with metastatic 5TGM1, VLA-4-MI1-PD 20nm micelles conferred significant survival benefit (T/D) over the 20nm targeted no drug (T/ND) or untreated controls (NT/ND) (52 days vs. 29 days, p=0.001) and versus the 200nm VLA-4-MI1-PD nanocolloid and its controls.

Conclusion: These finding support the feasibility of a new VLA-4-directed nanotherapy to deliver lipase-labile cMyc prodrug to disrupt MYC-MAX dimerization and improve MM survival.

Citation Format: Deepti Soodgupta, Dipanjan Pan, Grace Cui, Angana Senpan, Xiaoxia Yang, Samuel A. Wickline, Edward V. Prochownik, Katherine N. Weilbaecher, Michael H. Tomasson, Gregory M. Lanza. VLA-4 targeted nanoparticles deliver a cMYC-MAX prodrug antagonist extends survival a metastatic myeloma mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5381. doi:10.1158/1538-7445.AM2014-5381