bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro Modeling of Human Pancreatic Duct Epithelial Cell Transformation Defines Gene Expression Changes Induced by K-ras Oncogenic Activation in Pancreatic Carcinogenesis
Authors: Qian Jiaying , Niu Jiangong , Li Ming , Chiao Paul J. , Tsao Ming-Sound 
Published: September 2005

Abstract
Genetic analysis of pancreatic ductal adenocarcinomas and their putative precursor lesions, pancreatic intraepithelial neoplasias (PanIN), has shown a multistep molecular paradigm for duct cell carcinogenesis. Mutational activation or inactivation of the K-ras, p16INK4A, Smad4, and p53 genes occur at progressive and high frequencies in these lesions. Oncogenic activation of the K-ras gene occurs in &gt;90% of pancreatic ductal carcinoma and is found early in the PanIN-carcinoma sequence, but its functional roles remain poorly understood. We show here that the expression of K-rasG12V oncogene in a near diploid HPV16-E6E7 gene immortalized human pancreatic duct epithelial cell line originally derived from normal pancreas induced the formation of carcinoma in 50% of severe combined immunodeficient mice implanted with these cells. A tumor cell line established from one of these tumors formed ductal cancer when implanted orthotopically. These cells also showed increased activation of the mitogen-activated protein kinase, AKT, and nuclear factor-κB pathways. Microarray expression profiling studies identified 584 genes whose expression seemed specifically up-regulated by the K-ras oncogene expression. Forty-two of these genes have been reported previously as differentially overexpressed in pancreatic cancer cell lines or primary tumors. Real-time PCR confirmed the overexpression of a large number of these genes. Immunohistochemistry done on tissue microarrays constructed from PanIN and pancreatic cancer samples showed laminin β3 overexpression starting in high-grade PanINs and occurring in &gt;90% of pancreatic ductal carcinoma. The in vitro modeling of human pancreatic duct epithelial cell transformation may provide mechanistic insights on gene expression changes that occur during multistage pancreatic duct cell carcinogenesis.
Expression of Siva-1 Protein or Its Putative Amphipathic Helical Region Enhances Cisplatin-Induced Apoptosis in Breast Cancer Cells: Effect of Elevated Levels of BCL-2
Authors: Chu Fei , Barkinge John , Hawkins Sarah , Gudi Radhika , Salgia Ravi , Kanteti Prasad V.S. 
Published: September 2005

Abstract
cis-Diaminedichloroplatinum (II) (cisplatin) is routinely used to treat various types of cancers; however, a significant number develop resistance. One of the underlying factors that contribute to cisplatin resistance is the elevated level of BCL-2 and/or BCL-XL, which promotes cell survival. A potential method of overcoming such resistance is to use a potentiator that is capable of neutralizing the antiapoptotic effects of BCL-2/BCL-XL, such as Siva-1. We previously cloned the proapoptotic protein Siva-1 and showed a possible role for it in both extrinsic and intrinsic apoptosis. Using an adenovirus-based expression system, we now show that Siva-1 can synergize with cisplatin in inducing apoptosis in MCF7 and MDA-MB-231 breast cancer cells. In an anchorage-independent clonogenicity assay, MCF7/caspase-3 cells stably expressing Siva-1, but not the control cells, showed a dramatic decrease in the number of colonies formed on one-time cisplatin treatment. Further, we show that the unique putative amphipathic helical region (SAH) in Siva-1 (amino acid residues 36-55) is necessary and sufficient for the observed enhancement in cisplatin-induced apoptosis by Siva-1. Although cisplatin treatment results in significant elevation in the expression of Fas ligand and intracellular p21 levels, expression of Siva-1 has no additional benefit. Instead, the enhancement in apoptosis seems to be due to activation of intrinsic pathway that involves caspase-9 activation. Moreover, Siva-1 augments cisplatin-mediated cell death in MCF7 cells stably expressing BCL-2. We therefore propose that Siva-1 or its SAH region can be used as a potentiator of cisplatin-based chemotherapy.
Effect of Conditional Knockout of the Type II TGF-β Receptor Gene in Mammary Epithelia on Mammary Gland Development and Polyomavirus Middle T Antigen Induced Tumor Formation and Metastasis
Authors: Forrester Elizabeth , Chytil Anna , Bierie Brian , Aakre Mary , Gorska Agnieszka E. , Sharif-Afshar Ali-Reza , Muller William J. , Moses Harold L. 
Published: September 2005

Abstract
Transforming growth factor–β (TGF-β) isoforms are growth factors that function physiologically to regulate development, cellular proliferation, and immune responses. The role of TGF-β signaling in mammary tumorigenesis is complex, as TGF-β has been reported to function as both a tumor suppressor and tumor promoter. To elucidate the role of TGF-β signaling in mammary gland development, tumorigenesis, and metastasis, the gene encoding type II TGF-β receptor, Tgfbr2, was conditionally deleted in the mammary epithelium (Tgfbr2MGKO). Loss of Tgfbr2 in the mammary epithelium results in lobular-alveolar hyperplasia in the developing mammary gland and increased apoptosis. Tgfbr2MGKO mice were mated to the mouse mammary tumor virus-polyomavirus middle T antigen (PyVmT) transgenic mouse model of metastatic breast cancer. Loss of Tgfbr2 in the context of PyVmT expression results in a shortened median tumor latency and an increased formation of pulmonary metastases. Thus, our studies support a tumor-suppressive role for epithelial TGF-β signaling in mammary gland tumorigenesis and show that pulmonary metastases can occur and are even enhanced in the absence of TGF-β signaling in the carcinoma cells.
Loss of Heterozygosity Patterns Provide Fingerprints for Genetic Heterogeneity in Multistep Cancer Progression of Tobacco Smoke–Induced Non–Small Cell Lung Cancer
Authors: Pan Hongjie , Califano Joseph , Ponte Jose F. , Russo Andrea L. , Cheng Kuang-hung , Thiagalingam Arunthathi , Nemani Pratima , Sidransky David , Thiagalingam Sam 
Published: September 2005

Abstract
Dilution end point loss of heterozygosity (LOH) analysis, a novel approach for the analysis of LOH, was used to evaluate allelic losses with the use of 21 highly polymorphic microsatellite markers at nine chromosomal sites most frequently affected in smoking-related non–small cell lung cancers. Allelotyping was done for bronchial epithelial cells and matching blood samples from 23 former and current smokers and six nonsmokers as well as in 33 adenocarcinomas and 25 squamous cell carcinomas (SCC) and corresponding matching blood from smokers. Major conclusions from these studies are as follows: (a) LOH at chromosomal sites 8p, 9p, 11q, and 13q (P &gt; 0.05, Fisher's exact test) are targeted at the early stages, whereas LOH at 1p, 5q, 17p, and 18q (P &lt; 0.05, Fisher's exact test) occur at the later stages of non–small cell lung cancer progression; (b) LOH at 1p, 3p, 5q, 8p, 9p, 11q, 13q, 17p, and 18q occurs in over 45% of the tobacco smokers with SCC and adenocarcinoma; (c) compared with bronchial epithelial cells from smokers, there is a significantly higher degree of LOH at 1p, 5q, and 18q in adenocarcinoma and at 1p, 3p, and 17p in SCC (P &lt; 0.05, Fisher's exact test). We propose that lung cancer progression induced by tobacco smoke occurs in a series of target gene inactivations/activations in defined modules of a global network. The gatekeeper module consists of multiple alternate target genes, which is inclusive of but not limited to genes localized to chromosomal loci 8p, 9p, 11q, and 13q.
ABCB5-Mediated Doxorubicin Transport and Chemoresistance in Human Malignant Melanoma
Authors: Frank Natasha Y. , Margaryan Armen , Huang Ying , Schatton Tobias , Waaga-Gasser Ana Maria , Gasser Martin , Sayegh Mohamed H. , Sadee Wolfgang , Frank Markus H. 
Published: September 2005

Abstract
Enhanced drug efflux mediated by ABCB1 P-glycoprotein and related ATP-binding cassette transporters is one of several mechanisms of multidrug resistance thought to impair chemotherapeutic success in human cancers. In malignant melanoma, its potential contribution to chemoresistance is uncertain. Here, we show that ABCB5, which functions as a determinant of membrane potential and regulator of cell fusion in physiologic skin progenitor cells, is expressed in clinical malignant melanoma tumors and preferentially marks a subset of hyperpolarized, CD133+ stem cell phenotype-expressing tumor cells in malignant melanoma cultures and clinical melanomas. We found that ABCB5 blockade significantly reversed resistance of G3361 melanoma cells to doxorubicin, an agent to which clinical melanomas have been found refractory, resulting in a 43% reduction in the LD50 from 4 to 2.3 μmol/L doxorubicin (P &lt; 0.05). Our results identified ABCB5-mediated doxorubicin efflux transport as the underlying mechanism of resistance, because ABCB5 blockade significantly enhanced intracellular drug accumulation. Consistent with this novel ABCB5 function and mechanism in doxorubicin resistance, gene expression levels of the transporter across a panel of human cancer cell lines used by the National Cancer Institute for drug screening correlated significantly with tumor resistance to doxorubicin (r = 0.44; P = 0.016). Our results identify ABCB5 as a novel drug transporter and chemoresistance mediator in human malignant melanoma. Moreover, our findings show that ABCB5 is a novel molecular marker for a distinct subset of chemoresistant, stem cell phenotype-expressing tumor cells among melanoma bulk populations and indicate that these chemoresistant cells can be specifically targeted via ABCB5 to enhance cytotoxic efficacy.
Post-Transcriptional Regulation of the Androgen Receptor by Mammalian Target of Rapamycin
Authors: Cinar Bekir , De Benedetti Arrigo , Freeman Michael R. 
Published: September 2005

Abstract
Heparin-binding epidermal growth factor-like growth factor (HB-EGF), an ErbB1 ligand and prostate stromal growth factor, is an antagonist of androgen receptor (AR) function. In the LNCaP prostate cancer model, HB-EGF reduced AR protein levels and AR transactivation without affecting AR mRNA level or protein turnover. The signal to attenuate AR was mediated by the mammalian target of rapamycin, as shown by genetic and pharmacologic methods, and was independent of ErbB2/HER-2, extracellular signal-regulated kinase 1/2, and p38 mitogen-activated protein kinase pathways. Additional evidence suggests that AR protein levels are highly sensitive to regulation by cap-dependent mRNA translation. These findings reveal a novel mechanism for regulation of AR by a classic growth factor system and indicate that a rapamycin-sensitive post-transcriptional pathway can attenuate or possibly bypass AR-mediated signaling.
Kringle 5 of Human Plasminogen Induces Apoptosis of Endothelial and Tumor Cells through Surface-Expressed Glucose-Regulated Protein 78
Authors: Davidson Don J. , Haskell Catherine , Majest Sandy , Kherzai Abdullah , Egan David A. , Walter Karl A. , Schneider Andrew , Gubbins Earl F. , Solomon Larry , Chen Zhebo , Lesniewski Rick , Henkin Jack 
Published: September 2005

Abstract
Kringle 5 (K5) of human plasminogen has been shown to inhibit angiogenesis by inducing the apoptosis of proliferating endothelial cells. Peptide regions around the lysine-binding pocket of K5 largely mediate these effects, particularly the peptide PRKLYDY, which we show to compete with K5 for the binding to endothelial cells. The cell surface binding site for K5 that mediates these effects has not been defined previously. Here, we report that glucose-regulated protein 78, exposed on cell surfaces of proliferating endothelial cells as well as on stressed tumor cells, plays a key role in the antiangiogenic and antitumor activity of K5. We also report that recombinant K5-induced apoptosis of stressed HT1080 fibrosarcoma cells involves enhanced activity of caspase-7, consistent with the disruption of glucose-regulated protein 78-procaspase-7 complexes. These results establish recombinant K5 as an inhibitor of a stress response pathway, which leads to both endothelial and tumor cell apoptosis.
The Homeobox Gene Gax Inhibits Angiogenesis through Inhibition of Nuclear Factor-κB–Dependent Endothelial Cell Gene Expression
Authors: Patel Sejal , Leal Alejandro D. , Gorski David H. 
Published: September 2005

Abstract
The growth and metastasis of tumors are heavily dependent on angiogenesis, but much of the transcriptional regulation of vascular endothelial cell gene expression responsible for angiogenesis remains to be elucidated. The homeobox gene Gax is expressed in vascular endothelial cells and inhibits proliferation and tube formation in vitro. We hypothesized that Gax is a negative transcriptional regulator of the endothelial cell angiogenic phenotype and studied its regulation and activity in vascular endothelial cells. Several proangiogenic factors caused a rapid down-regulation of Gax mRNA in human vascular endothelial cells, as did conditioned media from breast cancer cell lines. In addition, Gax expression using a replication-deficient adenoviral vector inhibited human umbilical vein endothelial cell migration toward proangiogenic factors in vitro and inhibited angiogenesis in vivo in Matrigel plugs. To identify putative downstream targets of Gax, we examined changes in global gene expression in endothelial cells due to Gax activity. Gax expression resulted in changes in global gene expression consistent with a quiescent, nonangiogenic phenotype, with increased expression of cyclin kinase inhibitors and decreased expression of genes implicated in endothelial cell activation and angiogenesis. Further analysis revealed that Gax down-regulated numerous nuclear factor-κB (NF-κB) target genes and decreased the binding of NF-κB to its target sequence in electrophoretic mobility shift assays. To our knowledge, Gax is the first homeobox gene described that inhibits NF-κB activity in vascular endothelial cells. Because NF-κB has been implicated in endothelial cell activation and angiogenesis, the down-regulation of NF-κB–dependent genes by Gax suggests one potential mechanism by which Gax inhibits the angiogenic phenotype.
Both Antiangiogenesis- and Angiogenesis-Independent Effects Are Responsible for Hepatocellular Carcinoma Growth Arrest by Tyrosine Kinase Inhibitor PTK787/ZK222584
Authors: Liu Yuqing , Poon Ronnie T. , Li Qinyu , Kok Tsz Wai , Lau Cecilia , Fan Sheung Tat 
Published: September 2005

Abstract
Vascular endothelial growth factor (VEGF) plays an important role in tumor angiogenesis of hepatocellular carcinoma. Inhibition of VEGF receptors could theoretically reduce angiogenesis and tumor growth in hepatocellular carcinoma, but this remains to be proven with an experimental study. This study examined the angiogenesis-dependent and angiogenesis-independent activities of PTK787/ZK222584 (PTK787), a tyrosine kinase inhibitor of VEGF receptors, in nude mice bearing human hepatocellular carcinoma xenografts. The in vitro effects of PTK787 on proliferation, apoptosis, and cell cycle distribution in human hepatocellular carcinoma cell lines were also studied. Oral administration of PTK787 resulted in a significant reduction in tumor volume and microvessel formation of hepatocellular carcinoma xenografts in nude mice. PTK787 inhibited tumor cell proliferation in a dose-dependent manner and also induced tumor cells to undergo apoptosis both in vivo and in vitro. The proapoptotic response was associated with down-regulation of Bcl-2 and Bcl-xL expression and induction of cleavage of caspase-3. In addition, PTK787 induced growth arrest in hepatocellular carcinoma cells, which was associated with G1 arrest and partial G2-M block. This effect correlated with an increase in p21WAF1/ CIP1 (p21) and p27KIP1 (p27) protein expression. In conclusion, this study showed that PTK787 is a potent inhibitor of tumor growth in hepatocellular carcinoma by both antiangiogenic effect and direct effects on tumor cell proliferation and apoptosis. Our data suggest that blockage of VEGF receptors may provide an effective therapeutic approach for human hepatocellular carcinoma.
An Identity Crisis for fps/fes: Oncogene or Tumor Suppressor?
Authors: Sangrar Waheed , Zirgnibl Ralph A. , Gao Yan , Muller William J. , Jia Zongchao , Greer Peter A. 
Published: September 2005

Abstract
Fps/Fes proteins were among the first members of the protein tyrosine kinase family to be characterized as dominant-acting oncoproteins. Addition of retroviral GAG sequences or other experimentally induced mutations activated the latent transforming potential of Fps/Fes. However, activating mutations in fps/fes had not been found in human tumors until recently, when mutational analysis of a panel of colorectal cancers identified four somatic mutations in sequences encoding the Fps/Fes kinase domain. Here, we report biochemical and theoretical structural analysis demonstrating that three of these mutations result in inactivation, not activation, of Fps/Fes, whereas the fourth mutation compromised in vivo activity. These results did not concur with a classic dominant-acting oncogenic role for fps/fes involving activating somatic mutations but instead raised the possibility that inactivating fps/fes mutations might promote tumor progression in vivo. Consistent with this, we observed that tumor onset in a mouse model of breast epithelial cancer occurred earlier in mice targeted with either null or kinase-inactivating fps/fes mutations. Furthermore, a fps/fes transgene restored normal tumor onset kinetics in targeted fps/fes null mice. These data suggest a novel and unexpected tumor suppressor role for Fps/Fes in epithelial cells.
Nuclear Factor-κB Induced by Doxorubicin Is Deficient in Phosphorylation and Acetylation and Represses Nuclear Factor-κB–Dependent Transcription in Cancer Cells
Authors: Ho Wai Chi , Dickson Kathleen M. , Barker Philip A. 
Published: September 2005

Abstract
The primary goal of chemotherapy is to cause cancer cell death. However, a side effect of many commonly used chemotherapeutic drugs is the activation of nuclear factor-κB (NF-κB), a potent inducer of antiapoptotic genes, which may blunt the therapeutic efficacy of these compounds. We have assessed the effect of doxorubicin, an anthracycline in widespread clinical use, on NF-κB activation and expression of antiapoptotic genes in breast cancer cells. We show that doxorubicin treatment activates NF-κB signaling and produces NF-κB complexes that are competent for NF-κB binding in vitro. Surprisingly, these NF-κB complexes suppress, rather than activate, constitutive- and cytokine-induced NF-κB–dependent transcription. We show that doxorubicin treatment produces RelA, which is deficient in phosphorylation and acetylation and which blocks NF-κB signaling in a histone deacetylase–independent manner, and we show that NF-κB activated by doxorubicin does not remain stably bound to κB elements in vivo. Together these data show that NF-κB signaling induced by doxorubicin reduces expression of NF-κB–dependent genes in cancer cells.
Epigenetic Up-regulation of C-C Chemokine Receptor 7 and C-X-C Chemokine Receptor 4 Expression in Melanoma Cells
Authors: Mori Takuji , Kim Joseph , Yamano Tomoki , Takeuchi Hiroya , Huang Sharon , Umetani Naoyuki , Koyanagi Kazuo , Hoon Dave S.B. 
Published: September 2005

AbstractHistone deacetylation and DNA methylation establish epigenetic modifications, which through chromatin remodeling may result in gene silencing. We hypothesized that chemokine receptors C-C chemokine receptor 7 (CCR7) and C-X-C chemokine receptor 4 (CXCR4) on melanoma cells undergo epigenetic regulation. We investigated whether a histone deacetylase inhibitor and a demethylating agent influence CCR7 and CXCR4 expression on melanoma cells. Initially, microarray analysis was done to screen changes in chemokine receptor expression on melanoma cells after treatment with trichostatin A (TSA) and 5-Aza-2-deoxycytidine (5-Aza). CCR7 and CXCR4 mRNA expression were uniformly altered and selected for further investigation. Quantitative real-time reverse transcription-PCR assay, immunohistochemistry, and Western blot analysis were used to assess changes in mRNA and protein expression induced by TSA and 5-Aza in melanoma lines. Cell migration assays were conducted to assess the effects of altered CCR7 and CXCR4 expression on cell function. Treatment with TSA or 5-Aza increased gene expression of both CCR7 and CXCR4 in melanoma lines. TSA was the strongest enhancer. With combined treatment, CCR7 and CXCR4 mRNA expression was also up-regulated. Immunohistochemistry after combined treatment showed enhanced staining of both CCR7 and CXCR4 compared with control cells. Melanoma cell migration in TSA- and 5-Aza-treated cells was 7- and 2-fold higher than control cells for CCR7 and CXCR4, respectively. In summary, a histone deacetylase inhibitor and a demethylating agent up-regulated CCR7 and CXCR4 expression on melanoma cells. This increase in chemokine receptor expression correlated with functional activity. Most importantly, we have identified an epigenetic mechanism that may endogenously regulate chemokine receptor expression on melanoma cells.
SWI/SNF Chromatin-Remodeling Factors Induce Changes in DNA Methylation to Promote Transcriptional Activation
Authors: Banine Fatima , Bartlett Christopher , Gunawardena Ranjaka , Muchardt Christian , Yaniv Moshe , Knudsen Erik S. , Weissman Bernard E. , Sherman Larry S. 
Published: September 2005

Abstract
Brahma (Brm) and brahma-related gene-1 (Brg1) are mammalian homologues of SWI/SNF chromatin-remodeling factor subunits that can regulate both transcriptional activation and repression. Both Brg1 and Brm are mutated or deleted in numerous cancer cell lines, leading to the altered expression of genes that influence cell proliferation and metastasis. Here, we find that the promoters of two such genes, CD44 and E-cadherin, are hypermethylated in cells that have lost Brg1 or Brm. In two carcinoma cell lines that lack functional Brg1 and Brm, CD44 and E-cadherin expression are induced by the demethylating agent 5-aza-2′-deoxycytidine. Transfection with either Brg1 or Brm also induces CD44 and E-cadherin transcription and protein expression in these cells, as well as loss of methylation at sequences in the promoters of both genes. Chromatin immunoprecipitation assays show that Brg1 and Brm associate with these regions of the CD44 and E-cadherin promoters, suggesting that SWI/SNF protein complexes may directly influence the loss of DNA methylation. In vivo, Brm-deficient mice also show methylation and silencing of the CD44 promoter. Collectively, these data implicate loss of SWI/SNF-mediated transcriptional activation as a novel mechanism to increase DNA methylation in cancer cells and provide insight into the mechanisms underlying aberrant gene induction and repression during tumor progression.