bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B33: Intratumoral conversion of 5-fluorocytosine to 5-fluorouracil using a novel prodrug activator gene transfer technology in an immune-competent model of glioblastoma
Authors: Ostertag Derek , Amundson Karin , Buckley Taylor , Lopez Fernando E. , Martin Bryan , Gruber Harry , Gunzburg Walter , Perez Omar , Jolly Douglas J. , Robbins Joan M. 
Published: June 2012

Abstract
Background: Patients with the most common and aggressive form of brain cancer, glioblastoma multiforme (GBM), have poor prognosis and current treatments remain only palliative. Previous gene therapy approaches using replication-deficient viral vectors have demonstrated limited efficacy likely due to poor gene delivery to the tumor.
Methods: We used a novel replication-competent retroviral vector (Toca 511) designed and engineered to efficiently deliver a modified cytosine deaminase (CD) prodrug activating gene to glioma cells. Previous studies showed that such a replicating vector can preferentially infect intracranial human xenografts in nude mice (Tai et al. Mol Ther. 2005;12:842) and lead to increased survival in treatment groups compared to controls. In preparation for clinical trials we have improved the CD gene activity and further stabilized the vector structure to create Toca 511. We investigated the functionality of Toca 511 using stereotactic, intratumoral delivery in a syngeneic, orthotopic glioma model in immune-competent B6C3F1 mice. Freshly excised tumors were analyzed by quantitative PCR, Western, and HPLC.
Results: Brain tumors isolated from mice treated with Toca 511 and fluorocytosine (5FC) had observable expression of CD protein and vector copy numbers per genome that demonstrate efficient tumor infection. Extensive tumor specific viral spread with almost no spread of vector from the site of injection was observed in the first 24 days. Highly efficient intratumoral conversion of the 5FC prodrug into the anticancer drug 5-fluorouracil (5FU) was demonstrated after intraperitoneal or oral dosing with 5FC. Studies with Toca 511 at high and mid dose levels in combination with 5FC resulted in prolonged survival compared to controls (&gt; 5 months, p&lt;0.0036 and &lt;0.0354 respectively) in this syngeneic glioma model. The highest Toca 511 dose level tested in combination with 5-FC yielded no safety related findings in the mice.
Conclusions: Toca 511 efficiently delivers a functional CD gene for expression in glioma cells in a syngeneic, orthotopic model in immune-competent mice. Toca 511 increases survival through the delivery of CD gene and subsequent efficient conversion of 5FC into 5FU within the brain tumor with no safety related findings. A phase 1 ascending dose trial investigating the safety and tolerability of Toca 511 in combination with 5FC in patients with recurrent GBM is about to initiate.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B33.
Abstract B34: Inhibition of lung cancer cell invasion by siRNAs delivered by cell-specific aptamers
Authors: Wang Wei-Ya , Lai Wei-Yun , Hsiao Tzu-Hung , Peck Konan 
Published: June 2012

Abstract
Cell-specific delivery of therapeutic agents and targeted therapy are highly pursued topics in medical researches for treating cancers and other diseases. We aim to develop technologies enabling delivery of siRNA to cancer cells to retard or inhibit metastasis of the cancer cells with minimal adverse effects to normal cells. As long as the cancer cells do not invade and are confined, they can be eradicated by means such as surgical resection or radiation therapy.
Oligonucleotides of different sequences can fold into different conformations to bind to their targets with high specificity and affinity. These structured oligonucleotides are known as aptamers. We have identified new surface markers which prevalently expressed on lung cancer cells. By identifying functional aptamers against the surface marker proteins, we show that once the marker protein is activated by the aptamer, the surface marker protein/aptamer complex internalizes into the lung cancer cells. Therefore, it is feasible to employ the functional aptamer as a carrier to deliver siRNA into cancer cells to silence the expression of genes associated with metastasis. The aptamer-siRNA chimera is formed by chemical synthesis and bioconjguation methods. The chimera consists of an aptamer, which delivers therapeutic siRNA specifically to cancer cells but not normal cells to knock down the target genes that are pivotal in signaling pathways associated with the events of metastasis cascade. The effective knockdown of the metastasis associated genes by the nucleic acid chimera is verified by employing a series of invasion assays such as wound healing, Matrigel, filopodia formation, and others. The in vitro experimental results show that the aptamer-siRNA chimera is able to deliver therapeutics to specific target cells and silence the expression of the target genes in the cells. The in vitro experimental results are further verified by in vivo xenograft mouse model with immunohistochemistry examination, tumor size measurement, and circulating tumor cell detection by use of Alu sequence as the marker. By using lung cancer as a model, the data indicate that it is durable to employ the aptamer-siRNA chimera for cell- and target-specific therapy of cancer metastasis.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B34.
Abstract B36: Identification of carboxylesterase 2 as a hydrolase that cleaves the prodrug of gemcitabine LY2334737
Authors: Pratt Susan E. , Durland-Busbice Sara , Shepard Robert L. , Harlow Harry B. , Ballard Darryl , Heinz-Taheny Kathleen M. , Dantzig Anne H. 
Published: June 2012

Abstract
Gemcitabine hydrochloride is a nucleoside anticancer agent registered for the treatment of pancreatic, NSCLC, breast, and ovarian cancers. A prodrug of gemcitabine (LY2334737) was prepared that is a gemcitabine analog with an amide-linked valproate. This prodrug is noncytotoxic and must be hydrolyzed to release gemcitabine. In man, the prodrug is orally absorbed intact and converted to gemcitabine systemically. This study was undertaken to identify the enzyme responsible for hydrolysis of the prodrug to gemcitabine. The NCI-60 cell line panel was screened for prodrug sensitivity and microarray data were used to evaluate the expression of hydrolase enzymes in responsive and unresponsive cell lines. Cell extracts and candidate enzymes were tested for LY hydrolysis using HPLC and cell lines were evaluated for enzyme expression using qRT-PCR and Western methods. Screening of the NCI-60 panel demonstrated that LY was not cytotoxic to the majority of cell lines, however sensitivity was observed in a few cell lines such as SK-OV-3 and COLO205. Other cell lines were also evaluated. Extracts of drug sensitive cell lines hydrolyzed LY to gemcitabine and its inactive metabolite 2',2'-difluorodeoxyuridine (dFdU), indicating that LY hydrolysis was necessary for activity. Analysis of the expression of known hydrolases in the NCI-60 microarray data identified the serine ester hydrolase, carboxylesterase 1 (CES1) among the top candidates. In humans, there are 3 CESs and these are known to hydrolyze other prodrugs. Human recombinant protein of each CES was tested for LY cleavage. With long incubation periods, only CES2 hydrolyzed the drug. Loperamide is an inhibitor of CES1 and CES2 that is permeable to cells and noncytotoxic. At low micromolar concentrations this inhibitor only affects CES2, therefore cytotoxicity assays were conducted with SK-OV-3 in the presence and absence of 10 µM loperamide. The cytotoxicity of LY was decreased with loperamide CES2 inhibition without effect on gemcitabine cytotoxicity. Expression of CES2 was evaluated in drug-sensitive and -insensitive cell lines by qRT-PCR and Western analysis; LY sensitive lines expressed CES2 while insensitive lines did not. An immunohistochemical assay was developed that showed expression of CES2 to be heterogeneously expressed in these cell lines. Taken together, these data indicate that CES2 hydrolyzes the prodrug. Cancer cells that express CES2 may have an enhanced response to treatment with the prodrug LY2334737.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B36.
Abstract B37: Prognostic analysis of primary hepatic carcinoma with cancer embolus of biliary duct
Authors: Zhou Bao Tian 
Published: June 2012

Abstract
Background: In China, primary hepatic carcinoma (PHC) is one of the most frequent malignancies, which is more accompanied by cancer embolus of portal vein and is less with cancer embolus of biliary duct (CEBD) clinically. Anterior cases were diagnosed as PHC with CEBD by B ultrasound, CT, MRCP, or ERCP. Hepatectomy and choledochotomy were performed resecting the primary tumor and cleaning the CEBD completely, followed with TACE after operation. Nowaday ultrasound in biliary duct and orthotopic liver transplantation were worth considering as a brand new and extreme diagnose and treat method respectively. The article was intended to evaluate the clinicopathological characteristics and the prognosis of PHC with CEBD by therapeutic effect contrast to PHC with CEBD in different location.
Methods: The clinical data of 412 PHC patients with CEBD underwent surgical hepatectomy from 2000 to 2009 in the several hepatobiliary surgery centers of hospitals in China were retrospectively analyzed to research the clinicopathological characteristics and the prognosis. All the patients were divided into three groups based on distribution and location of CEBD.
Results: The overall 1 -year, 3-year, and 5-year survival rates from the time of operation were 76.8%, 53.4%, and 40.1 %, respectively. There was no significant difference in the prognosis between PHC patients with or without CEBD (P&gt;0.05). Independent factors affecting the prognosis of PHC patients were infiltration growth and multiple development. CEBD had no contribution in the prognosis of PHC patients. But the prognosis was different in PHC patients with different locations of cancer embolus in the biliary duct (P&lt;0.05).
Conclusion: Surgical operation remains the most effective treatment to PHC patients with CEBD. CEBD had no contribution in the prognosis of PHC patients. The location of the cancer embolus in the biliary duct was significant factors affecting the prognosis of PHC patients with CEBD. The prognosis was the worst in those PHC patients with CEBD located in the right hepatic duct.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B37.
Abstract B4: Chromosome 17p13.1 (KCTD11), a smoking-related susceptible region linked to lung cancer risk in Korean populations
Authors: Lee Yeiwon , Lee Minhyeok , Cho Hyunjung , Hong Jeeyoung , Kwon Seonjung , Park Chang-Gyo , Lee Hoi-Young , Son Ji-Woong , Kang Jaeku , Hong Jeeyoung 
Published: June 2012

Abstract
Lung cancer is the most common cause of cancer death worldwide. Smoking is known as the strongest single factor for the development of lung cancer. However, there are inherited genetic factors that cause different responses to cigarette smoking exposure among individuals. We tried to identify these differences in heavy smokers by examining copy number variations (CNVs) between lung cancer patients and healthy controls. Analysis by array comparative genomic hybridization (aCGH) showed 26 significant (P&lt;0.05) clones with either copy number gains or losses. 3 genes, KCTD11, FGF11, and PTPRH on chromosomal regions 17p13.1 (KCTD11 and FGF11) and 19q13.42 (PTPRH) were selected (P&lt;0.001) and tested by realtime quantitative PCR (qPCR) with 34 healthy controls and 54 lung cancer patients for large-scale analysis. KCTD11, a known tumor suppressor gene, showed copy number losses in cancer patients. In addition, as the years of smoking increased, odds ratios were also increased (0R=0.8,2.2, and 16.0), implying that it is a susceptible gene to lung cancer when an individual smokes. Therefore, KCTD11 is a promising candidate for a predictive marker to identify individuals with high, inherited genetic risk for the development of lung cancer.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B4.
Abstract B40: PALB2-KEAP1 interaction links oxidative stress to cancer and Fanconi anemia
Authors: Ma Jianglin , Xia Bing 
Published: June 2012

Abstract
PALB2/FANCN is mutated or silenced in breast, ovarian and pancreatic cancers and Fanconi anemia. It was initially discovered as a major binding protein for BRCA2 and controls the function of BRCA2 in homologous recombination, DNA double strand break repair and tumor suppression (Xia et al 2006). Nowadays, PALB2 itself has been also identified as a BRCA2-like breast cancer susceptibility protein and links BRCA1 and BRCA2 in the DNA damage response (Zhang and Ma et al 2009, Sy et al 2009). Therefore, PALB2 has been thought as an integral component of BRCA complex required for maintaining genomic stability via DNA recombinational repair.
In order to explore what other functions PALB2 protein may have, we performed a comprehensive search of PALB2-binding partners using the tandem affinity purification (TAP) assay combined with tandem mass spectrometry (LC-MS/MS) analysis. We show that PALB2 directly interacts with KEAP1, an oxidative stress sensor that binds and represses the anti-oxidant transcription factor NRF2. NRF2-KEAP1 pathway has been characterized as an important endogenous mechanism for combating oxidative stress. Oxidative stress-induced damage can lead to a variety of pathologies such as cancer, Parkinson's diseases, diabetes, Alzheimer's diseases and the aging process (Valko et al 2007). We demonstrate that PALB2 shares a conserved “ETGE” motif with NRF2 and competes with NRF2 for KEAP1 binding, thereby relieving NRF2 from KEAP1-mediated repression. As such, PALB2 promotes NRF2 nuclear accumulation, protects cells against oxidative stress and reduces cellular level of reactive oxygen species (ROS). Our findings establish a new function for PALB2 and provide a direct link between oxidative stress and the predisposition of cancer and Fanconi anemia.
References:
1. Xia B et al. Mol Cell. 2006;22:719.
2. Zhang F et al. Curr Biol. 2009;19:524.
3. Sy S et al. Proc Natl Acad Sci USA. 2009;106:7155.
4. Valko M et al. Int J Biochem Cell Biol. 2006;39:44.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B40.
Abstract B41: Restoring sensitivity to anti-EGFR-based therapy in lung adenocarcinoma by downstream modulation of the FOXO1/KLF6 transcriptional network
Authors: Sangodkar Jaya , Katz Suzanna , Albano Tara , Melville Heather , Burstein David , Politi Katerina , Difeo Analisa , Narla Goutham 
Published: June 2012

Abstract
Anti-EGFR-based strategies have shown clinical efficacy in the treatment of metastatic lung adenocarcinoma. Nevertheless, treatment resistance invariably develops through either de novo activation of downstream RAS/AKT signaling or acquired mutations in the Epidermal growth factor receptor (EGFR). A more thorough molecular characterization of the downstream mediators of EGFR signaling may lead to the development of newer classes of targeted molecular therapies to treat resistant disease. Here we identify a transcriptional network involving the KLF6 and FOXO1 tumor suppressor genes that regulate response to anti-EGFR-based therapies in both cell culture and in vivo models of the disease. Specifically, inhibition of AKT signaling promotes FOXO1 stabilization resulting in transactivation of the KLF6 tumor suppressor gene and induction of apoptosis in lung adenocarcinoma cell lines. Furthermore, the use of FDA-approved drug trifluoperazine hydrochloride, a FOXO1 nuclear export inhibitor restores sensitivity to erlotinib-resistant cell lines through modulation of the KLF6/FOXO1 signaling cascade in both cell culture and xenograft lung adenocarcinoma models. In addition, quantitative real-time PCR-based analysis and Western blotting confirm a significant correlation between activated oncognic EGFR signaling and downregulation of the FOXO1 and KLF6 tumor suppressor gene network in both primary human lung adenocarcinoma patient samples and a transgenic mouse model of the disease. Combined, these studies define a novel transcriptional network regulating oncogenic EGFR signaling and identify targeted molecular agents to restore chemosensitivity to anti-EGFR-based therapy in culture and in vivo.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B41.
Abstract B42: Molecular and cytogenetic characterization of novel multidrug-resistant human tumor cell lines
Authors: Ruzdijic Sabera , Podolski-Renic Ana , Pesic Milica , Chiourea Maria , Bankovic Jasna , Andjelkovic Tijana , Milinkovic Vedrana , Tanic Nikola , Gagos Sarantis 
Published: June 2012

Abstract
Multidrug resistance (MDR) is the major cause of failure to a successful cancer treatment. Cancer cells manifesting MDR phenotype are cross-resistant to many structurally and functionally unrelated drugs. The purpose of this study was to establish in vitro models, i.e., resistant cell lines, to further investigate the mechanisms of MDR. We used the human colon cancer cell line DLD1 and the glioma cell line U87 to establish paclitaxel-resistant cell lines, DLD1 -TxR and U87-TxR, by continuous exposure to stepwise increasing concentrations of the drug. The newly established, DLD1 -TxR and U87-TxR cell lines showed extensive resistance to paclitaxel (301-fold and 103-fold respectively). They also demonstrated cross-resistance to other anticancer agents such as doxorubicin, epirubicin, vinblastin, and etoposide. Cytogenetic data based on inverted-DAPI Banding, demonstrated that both resistant cell lines retained several karyotypic characteristics of their sensitive counterparts and also acquired novel structural or numerical chromosomal aberrations that may be related to resistance to chemotherapy. Interestingly, while the dividing parental U87 cells were mainly near-tetraploid, chemoresistance in the U87-TxR cell line was accompanied by one level ploidy reduction as verified by the increased prevalence of near-diploid cell populations. In addition, the DLD1 -TxR cells showed an increase tendency to loose the Y chromosome. Gene expression analyses revealed a 4-fold increase in the level of mdr1 mRNA in DLD1 -TxR cells. U87-TxR cells demonstrated prominent mdr1 activity since the expression in parental cells was undetectable. In contrast, the level of mrp1 mRNA was 40% decreased in both resistant cell lines. The expression of other MDR-related genes, topo IIα, and lrp, was unaffected by paclitaxel resistance. Flow cytometry analyses showed that the accumulation of rhodamine in resistant cells DLD1 -TxR and U87-TxR was significantly lower than in their sensitive counterparts, 17-fold and 8-fold, respectively. These results indicate that P-gp, encoded by mdr1 gene, is significantly overexpressed in both resistant cell lines and may account for paclitaxel resistance. In conclusion, the two novel resistant cell lines, DLD1 -TxR and U87-TxR may serve as appropriate models for the study of the mechanisms of paclitaxel resistance offering novel insights into potential targets for overcoming MDR that would improve the response to chemotherapy and patient outcome.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B42.
Abstract B43: Comparative proteomic analysis of colorectal cell lines to identify biomarkers for the prediction of intrinsic resistance to FOLFOX chemotherapy
Authors: Unger Florian T. , Meyer Markus , Spörl Monika , Harasym Agnieszka , Sullivan Kevin , Juhl Hartmut , David Kerstin A. 
Published: June 2012

Abstract
As there is a great interpatient variability in drug response caused by the individual geno- and phenotype the choice of optimal chemotherapy should be tailored for each patient. Intrinsic drug resistance is one of the main reasons for therapeutic ineffectiveness of first line therapy and recurrence in colorectal cancer. To advance individualized chemotherapy and understanding of drug resistance mechanisms, predictive biomarkers which indicate individual drug response of patients are urgently needed. The prediction of response to first line therapy will identify subgroups of patients who benefit from treatment and thus avoid ineffective treatment and associated side effects.
In this study, several commercially available cell lines as well as primary epithelial mixed cultures and clonal cell lines established from colorectal cancer patients were treated with different drugs, such as 5-fluorouracil, oxaliplatin, and drug combinations, e.g., FOLFOX. The determination of chemosensitivity of these cell lines to drug treatment was performed using two different assays, the ATPlite™-(Perkin Elmer) and FMC-assay (according to Larsson et al.). Both assays showed time- and dose-dependent drug responses which differed significantly among the 18 colorectal cell cultures. The analysis of obtained in vitro chemosensitivity data allowed us to cluster sensitive versus resistant cell lines by determining IC50-values. For the discovery of differentially expressed proteins which might be linked to a specific phenotypes of intrinsic chemoresistance we generated protein expression patterns from all 18 cell lines using a combination of reversed phase highperformance liquid chromatography and matrix-assisted laser desorption/ionization mass spectrometry (RP-HPLC MALDI MS). Up to 3500 m/z ion signals in the molecular mass range between 2500-35000 m/z were detected reflecting a complex pattern of small proteins and peptides. For protein identification, RP-HPLC fractionated samples were purified and digested by trypsin. Fragments of interest were subjected to MS/MS analysis in the TOF/TOF mode. The corresponding MS/MS spectra were used to search the NCBInr database using MASCOT software. Based on these data, we hope to gain more understanding of the biological processes of chemoresistance concerning important cellular drug responses (e.g., signal transduction pathways) and thereby obtain insight into new drug targets for future therapeutic intervention.
Citation Information: Clin Cancer Res 2010;16(14 Suppl):B43.