bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 493: NRF2 modulates sensitivity to thymidylate synthase inhibitors in colon cancer cells
Authors: Clinton Sarah A. , Barbour Karen W. , Ozer Ufuk , Berger Franklin G. 
Published: May 2015

Abstract
Thymidylate synthase (TYMS) catalyzes the reductive methylation of dUMP, and is the sole de novo source of thymidine for DNA replication and repair. As such, it is an important target of chemotherapeutic drugs, particularly the fluoropyrimidines 5-fluorouracil (FUra) and 5-fluoro-2’-deoxyuridine (FdUrd), as well as the folate analog raltitrexed (RTX). In cells, these drugs are metabolized to derivatives that bind to and inhibit TYMS, leading to depletion of thymidine levels, dysregulation of redox metabolism, generation of oxidative stress, and, eventually, apoptotic cell death. Gene expression profiles of FUra-treated HCT116 cells (a human colon cancer cell line) showed that a number of genes involved in redox metabolism are up-regulated following drug exposure. Several of these were recognized as known targets of nuclear factor-erythroid-2-related factor 2 (NRF2), a member of the cap ‘n’ collar family of bZIP transcription factors that confers protection against oxidative and electrophilic stress. Quantitative PCR assays verified that FUra, FdUrd, and RTX do indeed induce several NRF2-regulated genes, including AKR1B10, ALDH3A1, NQO1, and SERPINE1, among others. Overproduction of NRF2 via DNA transfection increased expression of some, but not all, of these genes, a phenomenon that was reversed by Kelch-like ECH-associated protein-1 (KEAP1), a known negative regulator of NRF2. The impact of TYMS inhibitors on expression of NRF2 target genes was maintained in the presence of exogenous thymidine and the antioxidant N-acetylcysteine, even though these agents completely ameliorated drug-induced apoptosis. This suggests that the response of NRF2 target genes to TYMS-directed drugs occurs independently of TYMS inhibition and subsequent oxidative stress. Utilizing siRNA technology, we examined the impact of NRF2 knockdown on drug-induced apoptosis, and found that increases in the apoptotic index following exposure to TYMS inhibitors were greater in NRF2-knockdown cells as compared to control cells. This was also observed in TYMS-overproducing cells that are profoundly drug resistant, and indicates that reduced NRF2 expression sensitizes cells to these TYMS inhibitors. Overall, we conclude that the induction of NRF2 target genes is a constraining factor in the cytotoxic response to TYMS inhibitors, and that inhibition of the transcription factor may be an effective strategy to enhance sensitivity to these agents.
Citation Format: Sarah A. Clinton, Karen W. Barbour, Ufuk Ozer, Franklin G. Berger. NRF2 modulates sensitivity to thymidylate synthase inhibitors in colon cancer 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 493. doi:10.1158/1538-7445.AM2014-493
Abstract 4933: In vivo visualization of heterogeneous cancer cell populations by fluorescence molecular tomography
Authors: Zanca Ciro , Inda Maria del Mar , Bonavia Rudy , Wykosky Jill , Verkhusha Vladislav , Cavenee Webster , Furnari Frank 
Published: May 2015

Abstract
Glioblastoma is the most common and aggressive tumor type that affects the central nervous system in adults. Despite advances in treatment strategies, its prognosis remains poor. EGFR and its mutant form EGFRvIII are amplified in a subset of clinical cases and interaction between cell populations expressing each receptor has been shown to enhance overall tumor growth. For instance, EGFRvIII induces expression of several secreted oncogenic factors, such as IL6 and LIF, which in turn stimulate the growth of EGFR expressing cells through an IL6 receptor (gp130)/EGFR cross-talk interaction. Therapy directed towards EGFR or EGFRvIII inhibition has been ineffective because of mechanisms that inhibit cell death. We hypothesize that these factors secreted by EGFRvIII expressing cells, in addition to promoting tumor growth, play a role in the failure of EGFR-directed therapies reported for glioblastoma. Preliminary data indicate that EGFRvIII-expressing cells prompt an IL6/LIF-mediated paracrine and autocrine antiapoptotic signaling cascade, leading to upregulation of the pro-survival protein, Survivin. RNAi-mediated downregulation of Survivin reverts this phenotype. To determine the effect of identified signaling effectors and cytokines in promoting EGFR tyrosine kinase inhibitor resistance, an in vivo model system of heterogeneous tumor growth was established and imaged using fluorescence molecular tomography (FMT) technology. Survivin, upstream pathways and cytokines were ablated in EGFR or EGFRvIII-expressing glioma cell lines tagged with different near infrared fluorescent proteins (turboFP635 or iRFP713). Orthotopically engrafted tumors of mixed EGFR/EGFRvIII populations were then evaluated for their tumor growth and cellular composition when challenged with EGFR tyrosine kinase inhibitors. In conclusion, this system allows for the validation of molecular mechanisms that promote cancer cell survival and establishes the basis for alternative treatment strategies.
Citation Format: Ciro Zanca, Maria del Mar Inda, Rudy Bonavia, Jill Wykosky, Vladislav Verkhusha, Webster Cavenee, Frank Furnari. In vivo visualization of heterogeneous cancer cell populations by fluorescence molecular tomography. [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 4933. doi:10.1158/1538-7445.AM2014-4933
Abstract 4942: Metastatic tumor migration in lymphatic vessels revealed by real-time intravital imaging
Authors: Fink Darci M. , Connor Alicia L. , Kelley Philip M. , Tempero Richard M. , Hollingsworth Michael A. 
Published: May 2015

Abstract
Distant tumor metastases and their confounding symptoms are often responsible for reduced patient quality-of-life and decreased overall survival. The main route of metastasis for many solid tumors is the lymphatic vasculature. The mechanisms of metastatic spread of tumor cells through the lymphatic vessels remain poorly understood. We have developed a novel transgenic mouse model and customized real-time intravital microscopy platforms to study the migration of tumor cells into lymphatic vessels in live animals over the course of several days. TdTomato fluorescent protein was expressed in lymphatic endothelial cells using an inductive CRE recombinase approach. This transgenic system coupled with the use of fluorescent stereomicroscopy techniques allowed us to visualize the cutaneous lymphatic vessel network with remarkable anatomic detail in living mice. We tracked the fate of CFSE-labeled B16 tumor cells administered cutaneously using two-color intravital fluorescence microscopy. This strategy allowed us to simultaneously visualize the lymphatic vessel network (red) and the B16 tumor cells (green) at single-cell resolution. We clearly visualized and documented several key behaviors of metastasizing tumor cells including single-cell intravasation, movement of tumor cells within vessels, clearing from vessels, and the accumulation of tumor cells in regional lymph nodes. These events occurred at a low frequency over the course of days in conditions of tissue homeostasis. Current studies are designed to define the anatomic site of tumor intravasation into lymphatic vessels and investigate how the inflamed tumor microenvironment affects tumor migration into the lymphatic vasculature.
Citation Format: Darci M. Fink, Alicia L. Connor, Philip M. Kelley, Richard M. Tempero, Michael A. Hollingsworth. Metastatic tumor migration in lymphatic vessels revealed by real-time intravital imaging. [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 4942. doi:10.1158/1538-7445.AM2014-4942
Abstract 4943: Visualization of endogenous melanoma initiation and progression using intravital microscopy
Authors: Bear James E. , Brighton Hailey E. , Sharpless Norman E. , Darr David B. , Clark Kelly S. 
Published: May 2015

Abstract
The death rates for malignant metastatic melanoma continue to rise because melanoma is largely refractory to existing therapies. Loss or inactivation of the tumor suppressor PTEN (Phosphatase and Tensin Homolog on Chromosome Ten) is observed in 40-50% of melanoma, and BRAF and PTEN mutations exist coincidentally in approximately 20% of melanoma cases. In mouse GEMM models, these mutations cooperate to promote metastatic melanomagenesis. However, existing methods to activate these lesions with Tyr-CreERT2 and topical tamoxifen application yields multifocal primary tumors whose origins cannot be accurately determined. To improve this model, we combined a tdTomatoLSL allele that serves as a visual marker of Cre recombination with Tyr-CreERT2;BrafCA;Ptenlox/lox to produce an animal where we can reproducibly initiate tumorigenesis in a spatiotemporally controllable manner by transiently applying extremely low doses (&lt;20 nM) of tamoxifen to the dermis of the ear. Due to melanocyte-specific expression of the fluorescent protein tdTomato, we can track tumor progression from endogenous cells using two-photon intravital imaging. Starting from a single primary tumor on the ear, we can detect distant metastases in cervical lymph nodes and lungs via macroscopic fluorescent imaging, qRT-PCR and histology. We are using this model in combination with targeted therapy to investigate the effects of selective molecular inhibitors on the growth and metastasis of endogenous BRAFV600E/PTEN-/- metastatic melanoma at the cellular level. Preliminary studies using intravital imaging and a selective MEK1/2 inhibitor, GSK212 (Trametinib, FDA approved treatment for metastatic melanoma) show that targeted therapy causes heterogeneous reorganization of the tumor cells as early as 3 days post-treatment. After several weeks of continuous treatment, the remaining, resistant tumor cells are highly correlated spatially with bundled collagen structures detected by second harmonic generation signal, suggesting that cellular milieu strongly influences drug response. In addition, GSK212 treated animals still had lung macro-metastatic tumors, indicating that despite continuous MEK1/2 inhibition, metastatic tumor growth in the lung was still possible. In summary, we have developed an inducible endogenous model of melanoma metastasis that can be used to directly investigate both heterogeneous effects of targeted therapy at the cellular level and the efficacy of targeted therapy against metastasis.
Citation Format: James E. Bear, Hailey E. Brighton, Norman E. Sharpless, David B. Darr, Kelly S. Clark. Visualization of endogenous melanoma initiation and progression using intravital microscopy. [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 4943. doi:10.1158/1538-7445.AM2014-4943
Abstract 495: Inactive status of cancer cells with suppression of AKT activity contributes to survival in chronic hypoxia
Authors: Inoue Masahiro , Okuyama Hiroaki , Endo Hiroko , Ohue Masayuki 
Published: May 2015

Abstract
A hypoxic microenvironment in tumors has been recognized as a cause of malignancy or resistance to various cancer therapies. In contrast to the recent progress in understanding the acute response of cancer cells to hypoxia, the characteristics of tumor cells in chronic hypoxia remain elusive. We have identified a pancreatic cancer cell line, AsPC-1, which is exceptionally able to survive for weeks under hypoxic conditions (1%O2) without changing medium at all, while most of the tested cancer cell lines died after several days under these conditions. Under hypoxic conditions, the AsPC-1 cells entered an “inactive status” characterized by no proliferation or death and by metabolic suppression. They recovered to active status after being placed again in optimal culture conditions. Under chronic hypoxia, ATP turnover, an indicator of energy demand, was markedly decreased, as was AKT phosphorylation. Forced activation of AKT resulted in increased ATP turnover and massive cell death in vitro. Xenograft tumors generated with AKT over-expressing cells showed remarkable decrease of inactive zone, where BrdU uptake and S6 phosphorylation were eliminated without any sign of cell death. We recently developed a novel culture system for primary cancer cells. In contrast to most cancer cell lines, primary colorectal cancer cells entered inactive status with AKT suppression under hypoxia combined with growth factor-depleted conditions. The ability of cancer cells to survive in a deteriorated microenvironment by entering into an inactive status might be a common property among cancer cells. The cancer cells in inactive status of both primary cultured cancer cells and AsPC-1 cells were resistant to chemotherapy. Targeting the regulatory mechanism inducing this inactive status might provide a new strategy for overcoming resistance to various cancer therapies.
Citation Format: Masahiro Inoue, Hiroaki Okuyama, Hiroko Endo, Masayuki Ohue. Inactive status of cancer cells with suppression of AKT activity contributes to survival in chronic hypoxia. [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 495. doi:10.1158/1538-7445.AM2014-495
Abstract 4950: Hypercholesterolemia promotes prostate cancer PC-3 metastases in orthotopic xenograft mice
Authors: Moon Hyeongsun , Sharpe Laura , Choi Eunju , Bielefeldt-Ohmann Helle , Nassar Zeyad , Parat Marie-Odile , Francois Mathias , Lee C Soon , Brown Andrew , Russell Pamela , Inder Kerry , Hill Michelle 
Published: May 2015

Abstract
Hypercholesterolemia has been proposed as a potential risk factor for advanced prostate cancer, and use of cholesterol-lowering drugs, statins, inversely correlates with advanced prostate cancer risk. Hypercholesterolemia increases growth of androgen-sensitive LNCaP xenograft in vivo, potentially via androgen signaling. The aim of this study was to determine if hypercholesterolemia affects castration-resistant prostate tumor progression using an androgen receptor-negative prostate cancer cell line PC-3. Compared to control media, cholesterol-deficient media reduced PC-3 proliferation, migration and anchorage-independent growth in vitro. While adding cholesterol did not significantly increase proliferation or anchorage-independent growth, cholesterol replacement in cholesterol-deficient media significantly increased PC-3 transmigration. In order to determine the in vivo effect, mice were randomly assigned to normal or hypercholesterolemic, isocaloric diet groups (N=14 and 15, respectively). After two weeks, hypercholesterolemic diet significantly increased circulating cholesterol but did not increase body weight. PC-3 cells stably expressing luciferase were orthotopically injected into the dorsolateral prostate. Tumor progression and metastases were monitored by in vivo and ex vivo optical bioluminescence imaging for 6 weeks. Strikingly, the results show that diet-induced hypercholesterolemia accelerated tumor metastases to lymph nodes, lung, proximal and distant bones without significantly affecting primary tumor growth. The metastases were confirmed histopathologcally. Hypercholesterolemia was not associated with elevated weight or circulating testosterone. This is the first study to directly demonstrate a causal relationship between hypercholesterolemia and prostate tumor metastases mediated through androgen-independent mechanisms, highlighting the potential clinical benefit of cholesterol lowering therapy such as statins in advanced, castration-resistant, prostate cancer patients.
Citation Format: Hyeongsun Moon, Laura Sharpe, Eunju Choi, Helle Bielefeldt-Ohmann, Zeyad Nassar, Marie-Odile Parat, Mathias Francois, C Soon Lee, Andrew Brown, Pamela Russell, Kerry Inder, Michelle Hill. Hypercholesterolemia promotes prostate cancer PC-3 metastases in orthotopic xenograft 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 4950. doi:10.1158/1538-7445.AM2014-4950
Abstract 4958: Fluorescent barcoding offers increased dimensionality in tracking tumor cells in vitro and in vivo
Authors: Hebron Katie E. , Ketova Tatiana , Arnold Shanna , Manning H. Charles , Sterling Julie , Elefteriou Florent , Zijsltra Andries 
Published: May 2015

Abstract
Fluorescent or luminescent imaging of tumors in animal models is a critical element in dynamic and longitudinal monitoring of tumor burden, tumor growth, and metastatic dissemination. Currently, most imaging strategies are limited to one or two different colors per animal. To improve utility of current imaging technologies, we have developed a library of fluorescent and luminescent tracking vectors designed to expand the color dimensions possible within a single model through a multi-label approach to fluorescent barcoding. The library was built using Multisite Gateway® Cloning technology, which offers a fast and simple recombination-based cloning approach that allows for efficient expression of several genes driven by one promoter on a single vector backbone. Our lentiviral-based vectors express firefly luciferase and one of seven spectrally unique fluorescent proteins covering the entire fluorescent protein color palette from blue to far-red. We have stably labeled bone-derived MDA-MB-231 cells with the vectors by viral transduction. Using these individually colored cell lines, we have demonstrated that the seven FPs are uniquely identifiable by spectral un-mixing with the Maestro Q Imaging System and by flow cytometry. The combination of luciferase and fluorescent labeling allows us to monitor tumor growth by luciferase activity and distinguish individual cell populations by their fluorescent label. We are currently verifying that the cells retain stable expression of the vectors in mouse models; preliminary results are promising. In the future, this system will be used to develop an elegant multi-label-based fluorescent barcoding strategy that will allow us to identify individual cell populations from a heterogeneous environment in vivo. By exploiting combinations of the seven fluorescent proteins, we could potentially create over 200 uniquely identifiable cells populations. This ability will not only reduce the number of animals necessary per experiment (as control and several experimental populations can be individually analyzed in a single mouse); but will also allow us to mimic the heterogeneous environment common to all human tumors.
Citation Format: Katie E. Hebron, Tatiana Ketova, Shanna Arnold, H. Charles Manning, Julie Sterling, Florent Elefteriou, Andries Zijsltra. Fluorescent barcoding offers increased dimensionality in tracking tumor cells in vitro and in vivo. [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 4958. doi:10.1158/1538-7445.AM2014-4958
Abstract 4965: Hypoxia has different effects on proliferation, migration and metastasis of various types of tumor cells
Authors: Tátrai Enikő , Bartal Alexandra , Fehér Zsuzsanna , Farkas Ákos , Paku Sándor , Kenessey István , Tóvári József 
Published: May 2015

Abstract
Hypoxia promotes angiogenesis and assigns radio- and chemotherapy resistance and aggressive phenotype to tumor cells. HIF-1 alpha, the main regulator of hypoxia induced processes, is activated in areas of low oxygen supply. Rho GTPases such as Rac1, cdc42 and RhoA play an important role in actin polimerization, depolimerization and stress fiber formation during tumor morphogenesis, cell adhesion, and cell migration. In the present study cell lines of melanoma (HT168-M1), fibrosarcoma (HT1080), colon cancer (HT25, HT29), lung cancer (H1975) and a head-neck cancer (PECA-PJ15) were cultured under normoxic and hypoxic conditions containing 1% and 5% O2. Proliferation tests with sulforhodamine B, migration assays with modified Boyden chamber and time-lapse videomicroscopy were performed with all cell lines. Furthermore, investigation of the expression and localization of HIF-1alpha, Rac1, cdc42 and RhoA mRNA by quantitative RT-PCR and immunfluorescence and the activation of small GTPases were performed. In addition, we examined the role of the hypoxic condition (CoCl2 administration) and HIF blockade (chetomin administration) on the metastatic potential of tumor cells using orthotopic xenograft models. The various tumor cell lines displayed different behaviour in vitro and in vivo. In the case of the most motile cell line (HT-168-M1), proliferation and migration capacity, moreover the gene expression patterns of small GTPases and HIF-1alpha were significantly higher under hypoxic conditions compared to normoxic cells. Migration capacity of the PECA-PJ15 cell line was higher when cultured under higher oxygen concentration. The hypoxic condition was less tolerated by both human colon carcinoma cell lines. In HT29 cells RhoA translocated into the nucleus under the hypoxic condition. The in vivo experiments demonstrated that primary tumor size and the number of metastasis were the largest in the CoCl2-treated group, and the smallest in the chetomin-treated group. In conclusion, our findings support that different phenotypes of the cancer cells form under hypoxia presumably via different pathways. This work is supported by OTKA K84173.
Citation Format: Enikő Tátrai, Alexandra Bartal, Zsuzsanna Fehér, Ákos Farkas, Sándor Paku, István Kenessey, József Tóvári. Hypoxia has different effects on proliferation, migration and metastasis of various types of tumor 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 4965. doi:10.1158/1538-7445.AM2014-4965