bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcriptional Repression of SKP2 Is Impaired in MYCN-Amplified Neuroblastoma
Authors: Muth Daniel , Ghazaryan Seda , Eckerle Isabella , Beckett Emily , Pöhler Christina , Batzler Julia , Beisel Claudia , Gogolin Sina , Fischer Matthias , Henrich Kai-Oliver , Ehemann Volker , Gillespie Paul , Schwab Manfred , Westermann Frank 
Published: April 2010

Abstract
The cell cycle regulator, SKP2, is overexpressed in various cancers and plays a key role in p27 degradation, which is involved in tumor cell dedifferentiation. Little is known about the mechanisms leading to impaired SKP2 transcriptional control in tumor cells. We used neuroblastoma as a model to study SKP2 regulation because SKP2 transcript levels gradually increase with aggressiveness of neuroblastoma subtypes. The highest SKP2 levels are found in neuroblastomas with amplified MYCN. Accordingly, we found 5.5-fold (range, 2–9.5) higher SKP2 core promoter activity in MYCN-amplified cells. Higher SKP2 core promoter activity in MYCN-amplified cells is mediated through a defined region at the transcriptional start site. This region includes a specific E2F-binding site that makes SKP2 activation largely independent of mitogenic signals integrated through the SP1/ELK-1 site. We show by chromatin immunoprecipitation that SKP2 activation through the transcriptional start site in MYCN-amplified cells is associated with the low abundance of pRB-E2F1 complexes bound to the SKP2 promoter. Transcriptional control of SKP2 through this regulatory mechanism can be reestablished in MYCN-amplified cells by restoring pRB activity using selective small compound inhibitors of CDK4. In contrast, doxorubicin or nutlin-3 treatment—both leading to p53-p21 activation—or CDK2 inhibition had no effect on SKP2 regulation in MYCN-amplified cells. Together, this implies that deregulated MYCN protein levels in MYCN-amplified neuroblastoma cells activate SKP2 through CDK4 induction, abrogating repressive pRB-E2F1 complexes bound to the SKP2 promoter. Cancer Res; 70(9); 3791–802. ©2010 AACR.
Disulfiram Treatment Facilitates Phosphoinositide 3-Kinase Inhibition in Human Breast Cancer Cells In vitro and In vivo
Authors: Zhang Haijun , Chen Di , Ringler Jonathan , Chen Wei , Cui Qiuzhi Cindy , Ethier Stephen P. , Dou Q. Ping , Wu Guojun 
Published: April 2010

Abstract
Frequent genetic alterations of the components in the phosphoinositide 3-kinase (PI3K)/PTEN/AKT signaling pathway contribute greatly to breast cancer initiation and progression, which makes targeting this signaling pathway a promising therapeutic strategy for breast cancer treatment. In this study, we showed that in the presence of copper (Cu), disulfiram (DSF), a clinically used antialcoholism drug, could potently inhibit breast cancer cell growth regardless of the PIK3CA status. Surprisingly, the treatment with a mixture of DSF and copper (DSF-Cu) led to the decreased expression of PTEN protein and the activation of AKT in a dose- and time-dependent manner in different cell lines with or without PIK3CA mutations. Treatment of breast cancer cell lines with a combination of DSF-Cu and LY294002, a pan-PI3K inhibitor, resulted in the significant inhibition of cell growth when compared with either drug alone. In addition, the combined treatment of DSF and LY294002 significantly inhibited the growth of the breast tumor xenograft in nude mice induced by MDA-MB-231 cells expressing mutant PIK3CA-H1047R and PIK3CA-E545K, whereas neither DSF nor LY294002 alone could significantly retard tumor growth. Finally, the observed in vivo inhibitory effects are found associated with aberrant signaling alterations and apoptosis-inducing activities in tumor samples. Thus, our finding shows for the first time that treatment of breast cancer with DSF results in a novel feedback mechanism that activates AKT signaling. Our study also suggests that the combination of DSF and a PI3K inhibitor may offer a new combinational treatment model for breast cancer, particularly for those with PIK3CA mutations. Cancer Res; 70(10); 3996–4004. ©2010 AACR.
Activation of NF-κB Signaling by Inhibitor of NF-κB Kinase β Increases Aggressiveness of Ovarian Cancer
Authors: Hernandez Lídia , Hsu Sarah C. , Davidson Ben , Birrer Michael J. , Kohn Elise C. , Annunziata Christina M. 
Published: April 2010

Abstract
The NF-κB family of transcription factors has been implicated in the propagation of ovarian cancer, but the significance of constitutive NF-κB signaling in ovarian cancer is unknown. We hypothesized that constitutive NF-κB signaling defines a subset of ovarian cancer susceptible to therapeutic targeting of this pathway. We investigated the biological relevance of NF-κB in ovarian cancer using a small-molecule inhibitor of inhibitor of NF-κB kinase β (IKKβ) and confirmed with RNA interference toward IKKβ. We developed a gene expression signature of IKKβ signaling in ovarian cancer using both pharmacologic and genetic manipulation of IKKβ. The expression of IKKβ protein itself and the nine-gene ovarian cancer–specific IKKβ signature were related to poor outcome in independently collected sets of primary ovarian cancers (P = 0.02). IKKβ signaling in ovarian cancer regulated the transcription of genes involved in a wide range of cellular effects known to increase the aggressive nature of the cells. We functionally validated the effect of IKKβ signaling on proliferation, invasion, and adhesion. Downregulating IKKβ activity, either by a small-molecule kinase inhibitor or by short hairpin RNA depletion of IKKβ, blocked all of these cellular functions, reflecting the negative regulation of the target genes identified. The diversity of functions controlled by IKKβ in ovarian cancer suggests that therapeutic blockade of this pathway could be efficacious if specific IKKβ inhibitor therapy is focused to patients whose tumors express a molecular profile suggestive of dependence on IKKβ activity. Cancer Res; 70(10); 4005–14. ©2010 AACR.
Selective Autophagy in Cancer Development and Therapy
Authors: Dikic Ivan , Johansen Terje , Kirkin Vladimir 
Published: April 2010

Abstract
Like other cells in the body, tumor cells depend on the evolutionarily conserved autophagy pathway to survive starvation and stress. Simultaneously, autophagy represents an important tumor-suppressive mechanism. Recent studies have shed new light on this apparent discrepancy and revealed mechanisms by which autophagy can modulate different stages of cancer development. The molecular basis of selectivity in autophagy employs specific receptor molecules, such as p62/SQSTM1, which are able to link autophagy targets and autophagosomal membranes. We discuss the emerging principles of selective autophagy in cancer pathogenesis and treatment. Cancer Res; 70(9); 3431–4. ©2010 AACR.
Distinct Biological Roles for the Akt Family in Mammary Tumor Progression
Authors: Dillon Rachelle L. , Muller William J. 
Published: April 2010

Abstract
The phosphatidylinositol 3′ kinase/Akt pathway is frequently dysregulated in cancer, which can have unfavorable consequences in terms of cell proliferation, survival, metabolism, and migration. Increasing evidence suggests that Akt1, Akt2, and Akt3 play unique roles in breast cancer initiation and progression. We have recently shown that in contrast to Akt1, which accelerates mammary tumor induction in transgenic mice, Akt2 promotes metastasis of tumor cells without affecting the latency of tumor development. Despite the distinct phenotypic outputs resulting from Akt1 or Akt2 activation, very little is known about the mode by which such unique functions originate from these highly related kinases. Here we discuss potential mechanisms contributing to the differing functional specificity of Akt1 and Akt2 with respect to migration, invasion, and metastasis. Cancer Res; 70(11); 4260–4. ©2010 AACR.
Aurora Kinase A Promotes Ovarian Tumorigenesis through Dysregulation of the Cell Cycle and Suppression of BRCA2
Authors: Yang Gong , Chang Bin , Yang Fan , Guo Xiaoqing , Cai Kathy Qi , Xiao Xue (Sherry) , Wang Huamin , Sen Subrata , Hung Mien-Chie , Mills Gordon B. , Chang Sandy , Multani Asha S. , Mercado-Uribe Imelda , Liu Jinsong 
Published: April 2010

AbstractPurpose: Aurora kinase A (Aurora-A) is known to regulate genomic instability and tumorigenesis in multiple human cancers. The underlying mechanism, however, is not fully understood. We examined the molecular mechanism of Aurora-A regulation in human ovarian cancer.Experimental Design: Retrovirus-mediated small hairpin RNA (shRNA) was used to silence the expression of Aurora-A in the ovarian cancer cell lines SKOV3, OVCA432, and OVCA433. Immunofluorescence, Western blotting, flow cytometry, cytogenetic analysis, and animal assay were used to test centrosome amplification, cell cycle alteration, apoptosis, DNA damage response, tumor growth, and genomic instability. Immunostaining of BRCA2 and Aurora-A was done in ovarian, pancreatic, breast, and colon cancer samples.Results: Knockdown of Aurora-A reduced centrosome amplification, malformation of mitotic spindles, and chromosome aberration, leading to decreased tumor growth. Silencing Aurora-A attenuated cell cycle progression and enhanced apoptosis and DNA damage response by restoring p21, pRb, and BRCA2 expression. Aurora-A was inversely correlated with BRCA2 in high-grade ovarian serous carcinoma, breast cancer, and pancreatic cancer. In high-grade ovarian serous carcinoma, positive expression of BRCA2 predicted increased overall and disease-free survival, whereas positive expression of Aurora-A predicted poor overall and disease-free survival (P &lt; 0.05). Moreover, an increased Aurora-A to BRCA2 expression ratio predicted poor overall survival (P = 0.047) compared with a decreased Aurora-A to BRCA2 expression ratio.Conclusion: Aurora-A regulates genomic instability and tumorigenesis through cell cycle dysregulation and BRCA2 suppression. The negative correlation between Aurora-A and BRCA2 exists in multiple cancers, whereas the expression ratio of Aurora-A to BRCA2 predicts ovarian cancer patient outcome. Clin Cancer Res; 16(12); 3171–81. ©2010 AACR.
Molecular Diagnosis of Activating EGFR Mutations in Non–Small Cell Lung Cancer Using Mutation-Specific Antibodies for Immunohistochemical Analysis
Authors: Kawahara Akihiko , Yamamoto Chizuko , Nakashima Kazutaka , Azuma Koichi , Hattori Satoshi , Kashihara Masaki , Aizawa Hisamichi , Basaki Yuji , Kuwano Michihiko , Kage Masayoshi , Mitsudomi Tetsuya , Ono Mayumi 
Published: April 2010

Abstract
Purpose: Therapeutic responses of non–small cell lung carcinoma (NSCLC) to epidermal growth factor receptor (EGFR)–targeted drugs, such as gefitinib and erlotinib, are closely associated with activating EGFR mutations. The most common mutations are delE746-A750 in exon 19 and L858R in exon 21, accounting for ∼90% of all EGFR mutations. Recently, EGFR mutation-specific antibodies were developed and did well in immunohistochemical analysis, giving a sensitivity of ∼90%. We have investigated whether this method detects activating EGFR mutations with sensitivity comparable with direct DNA sequencing, which is used to detect these mutations in NSCLC.
Experimental Design: We used antibodies specific for the E746-A750 deletion mutation in exon 19 and the L858R point mutation in exon 21 in Western blot analysis and immunohistochemistry to determine the presence of these mutations in NSCLC cell lines. We also examined these EGFR mutations in NSCLC tumor samples from 60 patients by immunohistochemically and direct DNA sequencing.
Results: We were able to identify EGFR mutations in NSCLC tumor samples immunohistochemically with a sensitivity of 79% using the anti–delE746-A750 antibody and 83% using the anti-L858R antibody. Additional DNA sequencing markedly improved the sensitivity obtained by immunohistochemistry.
Conclusions: This simple and rapid assay for detecting EGFR mutations, even in the small bronchial biopsies obtained in stage IV NSCLC patients, will be useful for diagnosing responsiveness to EGFR-targeted drugs in patients with NSCLC. Combining this with DNA sequencing is recommended for the development of improved personalized EGFR-targeted therapeutics. Clin Cancer Res; 16(12); 3163–70. ©2010 AACR.
Inhibition of the Insulin-Like Growth Factor I Receptor by Epigallocatechin Gallate Blocks Proliferation and Induces the Death of Ewing Tumor Cells
Authors: Kang Hyung-Gyoo , Jenabi Jasmine M. , Liu Xian Fang , Reynolds C. Patrick , Triche Timothy J. , Sorensen Poul H.B. 
Published: April 2010

Abstract
The insulin-like growth factor I receptor (IGFIR) has emerged as a key therapeutic target in many human malignancies, including childhood cancers such as Ewing family tumors (EFT). In this study, we show that IGFIR is constitutively activated in EFTs and that the major catechin derivative found in green tea, (−)-epigallocatechin gallate (EGCG), can inhibit cell proliferation and survival of EFT cells through the inhibition of IGFIR activity. Treatment of EFT cell lines with EGCG blocked the autophosphorylation of IGFIR tyrosine residues and inhibited its downstream pathways including phosphoinositide 3-kinase-Akt, Ras-Erk, and Jak-Stat cascades. EGCG treatment was associated with dose- and time-dependent inhibition of cellular proliferation, viability, and anchorage-independent growth, as well as with the induction of cell cycle arrest and apoptosis. Apoptosis in EFT cells by EGCG correlated with altered expression of Bcl-2 family proteins, including increased expression of proapoptotic Bax and decreased expression of prosurvival Bcl2, Bcl-XL, and Mcl-1 proteins. Our results provide further evidence that IGFIR is an attractive therapeutic target in EFTs and that EGCG is an effective inhibitor of this receptor tyrosine kinase. EGCG may be a useful agent for targeting IGFIR, either alone or in combination, with other potentially more toxic IGFIR inhibitors for the management of EFTs. Mol Cancer Ther; 9(5); 1396–407. ©2010 AACR.
AT7867 Is a Potent and Oral Inhibitor of AKT and p70 S6 Kinase That Induces Pharmacodynamic Changes and Inhibits Human Tumor Xenograft Growth
Authors: Grimshaw Kyla M. , Hunter Lisa-Jane K. , Yap Timothy A. , Heaton Simon P. , Walton Mike I. , Woodhead Steven J. , Fazal Lynsey , Reule Matthias , Davies Thomas G. , Seavers Lisa C. , Lock Victoria , Lyons John F. , Thompson Neil T. , Workman Paul , Garrett Michelle D. 
Published: April 2010

Abstract
The serine/threonine kinase AKT plays a pivotal role in signal transduction events involved in malignant transformation and chemoresistance and is an attractive target for the development of cancer therapeutics. Fragment-based lead discovery, combined with structure-based drug design, has recently identified AT7867 as a novel and potent inhibitor of both AKT and the downstream kinase p70 S6 kinase (p70S6K) and also of protein kinase A. This ATP-competitive small molecule potently inhibits both AKT and p70S6K activity at the cellular level, as measured by inhibition of GSK3β and S6 ribosomal protein phosphorylation, and also causes growth inhibition in a range of human cancer cell lines as a single agent. Induction of apoptosis was detected by multiple methods in tumor cells following AT7867 treatment. Administration of AT7867 (90 mg/kg p.o. or 20 mg/kg i.p.) to athymic mice implanted with the PTEN-deficient U87MG human glioblastoma xenograft model caused inhibition of phosphorylation of downstream substrates of both AKT and p70S6K and induction of apoptosis, confirming the observations made in vitro. These doses of AT7867 also resulted in inhibition of human tumor growth in PTEN-deficient xenograft models. These data suggest that the novel strategy of AKT and p70S6K blockade may have therapeutic value and supports further evaluation of AT7867 as a single-agent anticancer strategy. Mol Cancer Ther; 9(5); 1100–10. ©2010 AACR.
Targeting p70S6K Prevented Lung Metastasis in a Breast Cancer Xenograft Model
Authors: Akar Ugur , Ozpolat Bulent , Mehta Kapil , Lopez-Berestein Gabriel , Zhang Dongwei , Ueno Naoto T. , Hortobagyi Gabriel N. , Arun Banu 
Published: April 2010

Abstract
Overexpression of p70S6K in breast cancer patients is associated with aggressive disease and poor prognosis. Recent studies showed that patients with breast cancer with increased p70S6K phosphorylation had poor survival and increased metastasis. The purpose of our study was to determine whether knockdown of p70S6K would inhibit cell growth, invasion, and metastasis in breast cancer. We therefore stably knocked down p70S6K expression in MDA-231, a highly metastatic breast cancer cell line, using a lentiviral short hairpin RNA (shRNA) based approach. Inhibition of p70S6K led to inhibition of cell growth, migration, and invasion in vitro. To determine the role of p70S6K in breast cancer tumorigenesis and metastasis, we used an MDA-231 orthotopic and metastatic animal model. In the orthotopic model, mice injected with MDA-231–p70S6K shRNA cells developed significantly smaller tumors than control mice injected with MDA-231 control shRNA cells (P &lt; 0.01). No metastasis was observed in the p70S6K downregulated group, whereas lung metastasis was detected in all mice in the control group. To determine the role of p70S6K on growth and invasion, we tested downstream signaling targets by Western blot analysis. Knockdown of p70S6K inhibited phosphorylation of focal adhesion kinase, tissue transglutaminase 2, and cyclin D1 proteins, which promote cell growth, survival, and invasion. In addition, downregulation of p70S6K induced expression of PDCD4, a tumor-suppressor protein. In conclusion, we showed that p70S6K plays an important role in metastasis by regulating key proteins like cyclin D1, PDCD4, focal adhesion kinase, E-cadherin, β-catenin, and tissue transglutaminase 2, which are essential for cell attachment, survival, invasion, and metastasis in breast cancer. Mol Cancer Ther; 9(5); 1180–7. ©2010 AACR.
Transcriptional Analysis of an E2F Gene Signature as a Biomarker of Activity of the Cyclin-Dependent Kinase Inhibitor PHA-793887 in Tumor and Skin Biopsies from a Phase I Clinical Study
Authors: Locatelli Giuseppe , Bosotti Roberta , Ciomei Marina , Brasca Maria G. , Calogero Raffaele , Mercurio Ciro , Fiorentini Francesco , Bertolotti Matteo , Scacheri Emanuela , Scaburri Angela , Galvani Arturo , Pesenti Enrico , De Baere Thierry , Soria Jean-Charles , Lazar Vladimir , Isacchi Antonella 
Published: April 2010

Abstract
A transcriptional signature of the pan–cyclin-dependent kinase (Cdk) inhibitor PHA-793887 was evaluated as a potential pharmacodynamic and/or response biomarker in tumor and skin biopsies from patients treated in a phase I clinical study. We first analyzed the expression of a number of known E2F-dependent genes that were predicted to be modulated after Cdk2 and Cdk4 inhibition in xenograft tumor and skin samples of mice treated with the compound. This panel of 58 selected genes was then analyzed in biopsies from seven patients treated with PHA-793887 in a phase I dose escalation clinical trial in solid tumors. Quantitative real-time PCR or microarray analyses were done in paired skin and tumor biopsies obtained at baseline and at cycle 1. Analysis by quantitative real-time PCR of the signature in skin biopsies of patients treated at three different doses showed significant transcriptional downregulation with a dose-response correlation. These data show that PHA-793887 modulates genes involved in cell cycle regulation and proliferation in a clinical setting. The observed changes are consistent with its mechanism of action and correlate with target modulation in skin and with clinical benefit in tumors. Mol Cancer Ther; 9(5); 1265–73. ©2010 AACR.
A Bead-Based Activity Screen for Small-Molecule Inhibitors of Signal Transduction in Chronic Myelogenous Leukemia Cells
Authors: Sylvester Juliesta E. , Kron Stephen J. 
Published: April 2010

Abstract
Chronic myelogenous leukemia is characterized by the presence of the chimeric BCR-ABL gene, which is expressed as the constitutively active Bcr-Abl kinase. Although kinase activity is directly responsible for the clinical phenotype, current diagnostic and prognostic methods focus on a genetic classification system in which molecularly distinct subcategories are used to predict patient responses to small-molecule inhibitors of the Bcr-Abl kinase. Point mutations in the kinase domain are a central factor regulating inhibitor resistance; however, compensatory signaling caused by the activation of unrelated kinases can influence inhibitor efficacy. Kinase activity profiling can be used as a complementary approach to genetic screening and allows direct screening of small-molecule inhibitors. We developed a quantitative assay to monitor tyrosine kinase activities and inhibitor sensitivities in a model of chronic myelogenous leukemia using peptide reporters covalently immobilized on Luminex beads. Kinase activity is quantified by nonlinear regression from well-specific internal standard curves. Using optimized synthetic substrates and peptides derived from native substrates as probes, we measured kinase inhibition in cell lysates by the signal transduction inhibitors imatinib and dasatinib. Taking advantage of a convenient 96-well plate format, this assay also allows a straightforward and quantitative analysis of the differential effects of ATP and inhibitors on kinase activity. This method for analyzing a focused signaling network benefits from rigorous statistical analysis and short processing times, thereby offering a powerful tool for drug discovery and clinical testing. Mol Cancer Ther; 9(5); 1469–81. ©2010 AACR.
Extract of Oregano, Coffee, Thyme, Clove, and Walnuts Inhibits NF-κB in Monocytes and in Transgenic Reporter Mice
Authors: Paur Ingvild , Balstad Trude R. , Kolberg Marit , Pedersen Marit K. , Austenaa Liv M. , Jacobs David R. , Blomhoff Rune 
Published: April 2010

Abstract
The transcription factor NF-κB is a promising target for chemoprevention. Several dietary plants are efficient inhibitors of NF-κB activation in vitro and could act synergistically on the NF-κB signaling pathway. In this study, we tested whether dietary plant extracts could inhibit NF-κB activation in a synergistic manner in vitro. Second, we investigated the potency of the same dietary plant extracts in the inhibition of NF-κB activation in vivo. A combined extract of clove, oregano, thyme, walnuts, and coffee synergistically inhibited lipopolysaccaride (LPS)-induced NF-κB activation in a monocytic cell line, compared with the sum of effects from the single extracts. Transgenic NF-κB luciferase reporter mice were given a single dose of the combined extract and subsequently challenged with LPS. NF-κB activation was monitored by in vivo imaging for 6 hours. In addition, NF-κB activity in organs and the expression of immune-related genes in liver were investigated. Based on the area under the curve, the extract decreased whole body LPS-induced NF-κB activity the first 6 hours by 35% compared with control mice. Organ-specific NF-κB activation was inhibited in intestine, liver, testis, and epididymis of the mice receiving the combination extract. In addition, dietary plants reduced the expression of genes related to inflammation, cell migration, and proliferation in liver. This study shows that dietary plants may be potent modulators of NF-κB signaling both in vitro and in vivo, and thus support further investigation of consumption of these plant foods as part of a healthy diet or as a mode of chemoprevention. Cancer Prev Res; 3(5); 653–63. ©2010 AACR.