bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vascular Proliferation Is Important for Clinical Progress of Endometrial Cancer
Authors: Stefansson Ingunn M. , Salvesen Helga B. , Akslen Lars A. 
Published: March 2006

Abstract
Angiogenesis is essential for tumor growth, invasion, and metastatic spread. Whereas microvessel density (MVD) has been widely used as a measure of tumor-associated angiogenesis, we now wanted to examine the significance of other angiogenic markers, especially vascular proliferation (by Ki-67/factor VIII staining) and the degree of pericyte coverage [by α-smooth muscle actin (α-SMA)/factor VIII staining], in a large and population-based series of endometrial carcinoma with complete follow-up. Due to limited information on the role of lymphangiogenesis in these tumors, lymphatic vessel density (LVD) by LYVE-1 staining was also determined, as well as selected angiogenic factors [vascular endothelial growth factor (VEGF)-A, VEGF-C, VEGF-D and basic fibroblast growth factor (bFGF)], which could possibly be related to vascular proliferation and lymphangiogenesis. The information on angiogenic phenotype was related to clinicopathologic features and disease progress. Median vascular proliferation, as estimated by vascular proliferation index (VPI), was 3.9% and high VPI was associated with features of aggressive tumors and decreased survival. The prognostic effect of VPI was superior to that of MVD. Presence of pericyte coverage, as estimated by the α-SMA index (SMAI), was 35% and low SMAI was significantly associated with vascular invasion by tumor cells and impaired prognosis. Peritumoral lymphatic vessels (LVD-pt) were found in 39.5% of the cases and high LVD-pt was significantly associated with aggressive tumor features and decreased survival. In multivariate survival analysis, only the extent of vascular proliferation had independent prognostic effect, in addition to well-known clinicopathologic factors, whereas MVD did not have significant prognostic value. In conclusion, our study indicates that vascular proliferation is a meaningful variable in assessing the angiogenic phenotype of endometrial carcinoma. (Cancer Res 2006; 66(6): 3303-9)
Lysophosphatidic Acid Is Constitutively Produced by Human Peritoneal Mesothelial Cells and Enhances Adhesion, Migration, and Invasion of Ovarian Cancer Cells
Authors: Ren Juan , Xiao Yi-jin , Singh Lisam Shanjukumar , Zhao Xiaoxian , Zhao Zhenwen , Feng Li , Rose Tyler M. , Prestwich Glenn D. , Xu Yan 
Published: March 2006

Abstract
Lysophosphatidic acid (LPA) is both a potential marker and a therapeutic target for ovarian cancer. It is critical to identify the sources of elevated LPA levels in ascites and blood of patients with ovarian cancer. We show here that human peritoneal mesothelial cells constitutively produce LPA, which accounts for a significant portion of the chemotactic activity of the conditioned medium from peritoneal mesothelial cells to ovarian cancer cells. Both production of LPA by peritoneal mesothelial cells and the chemotactic activity in the conditioned medium can be blocked by HELSS [an inhibitor of the calcium-independent phospholipase A2 (iPLA2)] and AACOCF3 [an inhibitor of both cytosolic PLA2 (cPLA2) and iPLA2]. Moreover, cell-based enzymatic activity assays for PLA2 indicate that peritoneal mesothelial cells have strong constitutive PLA2 activity. Receptors for LPA, LPA2, and LPA3 are involved in the conditioned medium–induced chemotactic activity. Invasion of ovarian cancer cells into peritoneal mesothelial cells has also been analyzed and shown to require PLA2, LPA receptors, and the mitogen-activated protein/extracellular signal-regulated kinase kinase/extracellular signal-regulated kinase signaling pathway. Thus, we show here, for the first time, that human peritoneal mesothelial cells constitutively produce bioactive lipid signaling molecules, such as LPA, via iPLA2 and/or cPLA2 activities. Conditioned medium from peritoneal mesothelial cells stimulate migration, adhesion, and invasion of ovarian cancer cells, and may play similar roles in vivo. (Cancer Res 2006; 66(6): 3006-14)
Nuclear Insulin-Like Growth Factor Binding Protein-3 Induces Apoptosis and Is Targeted to Ubiquitin/Proteasome–Dependent Proteolysis
Authors: Santer Frédéric R. , Bacher Nicole , Moser Barbara , Morandell Dieter , Ressler Sigrun , Firth Sue M. , Spoden Gilles A. , Sergi Consolato , Baxter Robert C. , Jansen-Dürr Pidder , Zwerschke Werner 
Published: March 2006

Abstract
Insulin-like growth factor binding protein-3 (IGFBP-3), the product of a tumor suppressor target gene, can modulate cell proliferation and apoptosis by IGF-I-dependent and IGF-I-independent mechanisms. IGFBP-3 controls the bioavailability of IGFs in the extracellular environment and is known to be subject to degradation by various extracellular proteases. Although nuclear localization and functions of IGFBP-3 have been described in the past, we show as the novel features of this study that the abundance of nuclear IGFBP-3 is directly regulated by ubiquitin/proteasome–dependent proteolysis. We show that IGFBP-3 degradation depends on an active ubiquitin-E1 ligase, specific 26S proteasome inhibitors can efficiently stabilize nuclear IGFBP-3, and the metabolic half-life of nuclear IGFBP-3 is strongly reduced relative to cytoplasmic IGFBP-3. Nuclear IGFBP-3 is highly polyubiquitinated at multiple lysine residues in its conserved COOH-terminal domain and stabilized through mutation of two COOH-terminal lysine residues. Moreover, we show that IGFBP-3, if ectopically expressed in the nucleus, can induce apoptotic cell death. These results suggest that ubiquitin/proteasome–mediated proteolysis of IGFBP-3 may contribute to down-regulation of apoptosis. (Cancer Res 2006; 66(6): 3024-33)
The Oncogenic Epidermal Growth Factor Receptor Variant Xiphophorus Melanoma Receptor Kinase Induces Motility in Melanocytes by Modulation of Focal Adhesions
Authors: Meierjohann Svenja , Wende Elisabeth , Kraiss Anita , Wellbrock Claudia , Schartl Manfred 
Published: March 2006

Abstract
One of the most prominent features of malignant melanoma is the fast generation of metastasizing cells, resulting in the poor prognosis of patients with this tumor type. For this process, cells must gain the ability to migrate. The oncogenic receptor Xmrk (Xiphophorus melanoma receptor kinase) from the Xiphophorus melanoma system is a mutationally activated version of the epidermal growth factor receptor that induces the malignant transformation of pigment cells. Here, we show that the activation of Xmrk leads to a clear increase of pigment cell motility in a fyn-dependent manner. Stimulation of Xmrk induces its interaction with the focal adhesion kinase (FAK) and the interaction of active, receptor-bound fyn with FAK. This results in changes in FAK activity and induces the modulation of stress fibers and focal adhesions. Overexpression of dominant-negative FAK shows that the activity of innate FAK and a receptor-induced focal adhesion turnover are a prerequisite for pigment cell migration. Our findings show that in our system, Xmrk is sufficient for the induction of pigment cell motility and underlines a role of the src family protein tyrosine kinase fyn in melanoma development and progression. (Cancer Res 2006; 66(6): 3145-52)
Activation of Stat3 in Human Melanoma Promotes Brain Metastasis
Authors: Xie Tong-xin , Huang Feng-Ju , Aldape Kenneth D. , Kang Shin-Hyuk , Liu Mingguang , Gershenwald Jeffrey E. , Xie Keping , Sawaya Raymond , Huang Suyun 
Published: March 2006

Abstract
Brain metastasis is a major cause of morbidity and mortality in patients with melanoma. The molecular changes that lead to brain metastasis remain poorly understood. In this study, we developed a model to study human melanoma brain metastasis and found that Stat3 activity was increased in human brain metastatic melanoma cells when compared with that in cutaneous melanoma cells. The expression of activated Stat3 is also increased in human brain metastasis specimens when compared with that in the primary melanoma specimens. Increased Stat3 activation by transfection with a constitutively activated Stat3 enhanced brain metastasis, whereas blockade of Stat3 activation by transfection with a dominant-negative Stat3 suppressed brain metastasis of human melanoma cells in animal models. Furthermore, altered Stat3 activity profoundly affected melanoma angiogenesis in vivo and melanoma cell invasion in vitro and significantly affected the expression of basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and matrix metalloproteinase-2 (MMP-2) in vivo and in vitro. Finally, Stat3 activity transcriptionally regulated the promoter activity of bFGF in addition to VEGF and MMP-2 in human melanoma cells. These results indicated that Stat3 activation plays an important role in dysregulated expression of bFGF, VEGF, and MMP-2 as well as angiogenesis and invasion of melanoma cells and contributes to brain metastasis of melanoma. Therefore, Stat3 activation might be a new potential target for therapy of human melanoma brain metastases. (Cancer Res 2006; 66(6): 3188-96)
A Growth-Related Oncogene/CXC Chemokine Receptor 2 Autocrine Loop Contributes to Cellular Proliferation in Esophageal Cancer
Authors: Wang Bo , Hendricks Denver T. , Wamunyokoli Fred , Parker M. Iqbal 
Published: March 2006

AbstractGrowth-related oncogene (GRO), a member of the CXC chemokine subfamily, plays a major role in inflammation and wound healing. CXC chemokines have been found to be associated with tumorigenesis, angiogenesis, and metastasis. Although elevated expression of GRO has been reported in several human cancers, the expression and role of GRO and its receptor, CXCR2, in esophageal cancer are poorly understood. This study used real-time reverse transcription-PCR (RT-PCR) and immunohistochemical approaches to show that GROα, GROβ, and CXCR2 are up-regulated in esophageal tumor tissue. Furthermore, GROα, GROβ, and CXCR2 are constitutively expressed in WHCO1, an esophageal cancer cell line that was used as a model system here. GROβ enhances transcription of EGR-1, via the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, which can be blocked by a specific antagonist of CXCR2 (SB 225002) or specific antibody to GROβ. WHCO1 cells treated with SB 225002 exhibited a 40% reduction in cell proliferation. A stable WHCO1 GROα RNA interference (RNAi) clone displayed a 43% reduction in GROα mRNA levels as determined by real-time RT-PCR, reduced levels of GROα by fluorescence microscopy, and a 60% reduction in the levels of phosphorylated ERK1/2. A stable clone expressing GROβ RNAi displayed &gt;95% reduction in GROβ mRNA levels, reduced levels of GROβ by fluorescence microscopy, and an 80% reduction in the levels of phosphorylated ERK1/2. Moreover, these GROα RNAi- and GROβ RNAi-expressing clones displayed a 20% and 50% decrease in cell proliferation, respectively. Our results suggest that GROα-CXCR2 and GROβ-CXCR2 signaling contributes significantly to esophageal cancer cell proliferation and that this autocrine signaling pathway may be involved in esophageal tumorigenesis. (Cancer Res 2006; 66(6): 3071-7)
Erythroid Inhibition by the Leukemic Fusion AML1-ETO Is Associated with Impaired Acetylation of the Major Erythroid Transcription Factor GATA-1
Authors: Choi Youngjin , Elagib Kamaleldin E. , Delehanty Lorrie L. , Goldfarb Adam N. 
Published: March 2006

Abstract
Human acute myeloid leukemias with the t(8;21) translocation express the AML1-ETO fusion protein in the hematopoietic stem cell compartment and show impairment in erythroid differentiation. This clinical finding is reproduced in multiple murine and cell culture model systems in which AML1-ETO specifically interferes with erythroid maturation. Using purified normal human early hematopoietic progenitor cells, we find that AML1-ETO impedes the earliest discernable steps of erythroid lineage commitment. Correspondingly, GATA-1, a central transcriptional regulator of erythroid differentiation, undergoes repression by AML1-ETO in a nonconventional histone deacetylase–independent manner. In particular, GATA-1 acetylation by its transcriptional coactivator, p300/CBP, a critical regulatory step in programming erythroid development, is efficiently blocked by AML1-ETO. Fusion of a heterologous E1A coactivator recruitment module to GATA-1 overrides the inhibitory effects of AML1-ETO on GATA-1 acetylation and transactivation. Furthermore, the E1A-GATA-1 fusion, but not wild-type GATA-1, rescues erythroid lineage commitment in primary human progenitors expressing AML1-ETO. These results ascribe a novel repressive mechanism to AML1-ETO, blockade of GATA-1 acetylation, which correlates with its inhibitory effects on primary erythroid lineage commitment. (Cancer Res 2006; 66(6): 2990-96)
EGFR Tyrosine Kinase Inhibitors Decrease VEGF Expression by Both Hypoxia-Inducible Factor (HIF)-1–Independent and HIF-1–Dependent Mechanisms
Authors: Pore Nabendu , Jiang Zibin , Gupta Anjali , Cerniglia George , Kao Gary D. , Maity Amit 
Published: March 2006

Abstract
Epidermal growth factor receptor (EGFR) inhibitors can decrease vascular endothelial growth factor (VEGF) expression and tumor angiogenesis. In the current study, we investigate the molecular pathways by which this occurs using two drugs that have been used in the clinic, gefitinib (Iressa) and erlotinib (Tarceva). The decrease in VEGF expression by gefitinib in SQ20B squamous cell carcinoma cells was opposed by adenoviral expression of Akt in these cells. The hypoxia-inducible factor-1 (HIF-1) binding site located at approximately −1 kbp in the VEGF promoter was not required for down-regulation of promoter activity by gefitinib under normoxia. Furthermore, the drug decreased activity of a reporter containing the −88/+54 region. In a gel shift assay, gefitinib led to decreased retardation of a labeled DNA oligonucleotide probe corresponding to the −88/−66 region of the VEGF promoter, which contains Sp1 binding sites. These effects of gefitinib on VEGF promoter activity and DNA binding were both reversed by Akt expression. Phosphorylation of Sp1 was decreased in the presence of gefitinib. Gefitinib also decreases VEGF expression by decreasing HIF-1α expression. This occurs due to decreased protein translation without any change in the level of HIF-1α mRNA. Together, these results suggest that gefitinib decreases VEGF expression both by decreasing Sp1 binding to the proximal core VEGF promoter and by down-regulating HIF-1α expression. Similar results were obtained with erlotinib in SQ20B and gefitinib in HSC3 squamous carcinoma cells. These results indicate that there are at least two separate mechanisms by which EGFR inhibitors decrease VEGF expression. (Cancer Res 2006; 66(6): 3197-204)
PRL Tyrosine Phosphatases Regulate Rho Family GTPases to Promote Invasion and Motility
Authors: Fiordalisi James J. , Keller Patricia J. , Cox Adrienne D. 
Published: March 2006

Abstract
Phosphatase found in regenerating liver (PRL)-1, PRL-2, and PRL-3 [also known as PTP4A1, PTP4A2, and PTP4A3, respectively] constitute a unique family of putative protein tyrosine phosphatases (PTPs) modified by farnesylation. PRL-3 is amplified and its message is up-regulated in colorectal carcinoma metastases. Its ectopic expression promotes invasive and metastatic properties, supporting a causal link between PRL-3 and late-stage cancer development. However, neither PRL phosphatase substrates nor their signaling pathways have been defined. To address possible mechanisms for the biological activity of PRL-3, we sought to identify its downstream targets, reasoning that regulators of motility and invasion, such as the Rho family of small GTPases, might be logical candidates. We found that levels of active RhoA and RhoC were increased 4- to 7-fold in SW480 colorectal carcinoma cells expressing exogenous PRL-1 and PRL-3, and that PRL-mediated motility and Matrigel invasion were blocked by pharmacologic inhibition of Rho kinase (ROCK), a key Rho effector. In contrast, the activity of Rac was reduced by PRL PTPs, whereas Cdc42 activity was unaffected. PRL-3 stimulated transcription driven by the serum response element in a Rho-dependent manner. We also confirmed that the ability of PRL PTPs to induce invasion and motility is dependent on farnesylation. Catalytic PRL-3 mutants (C104A or D72A) were impaired in PRL-3-induced invasion and Rho activation, indicating that these properties require phosphatase activity. We conclude that PRL PTPs stimulate Rho signaling pathways to promote motility and invasion. Characterization of PRL activity and regulatory pathways should enhance efforts to understand and interfere with PRL-mediated events in invasion and metastasis. (Cancer Res 2006; 66(6): 3153-61)
An Inducible Mouse Model of Melanoma Expressing a Defined Tumor Antigen
Authors: Huijbers Ivo J. , Krimpenfort Paul , Chomez Patrick , van der Valk Martin A. , Song Ji-Ying , Inderberg-Suso Else-Marit , Schmitt-Verhulst Anne-Marie , Berns Anton , Van den Eynde Benoît J. 
Published: March 2006

Abstract
Cancer immunotherapy based on vaccination with defined tumor antigens has not yet shown strong clinical efficacy, despite promising results in preclinical models. This discrepancy might result from the fact that available preclinical models rely on transplantable tumors, which do not recapitulate the long-term host-tumor interplay that occurs in patients during progressive tumor development and results in tumor tolerance. To create a faithful preclinical model for cancer immunotherapy, we generated a transgenic mouse strain developing autologous melanomas expressing a defined tumor antigen recognized by T cells. We chose the antigen encoded by P1A, a well-characterized murine cancer germ line gene. To transform melanocytes, we aimed at simultaneously activating the Ras pathway and inactivating tumor suppressor Ink4a/Arf, thereby reproducing two genetic events frequently observed in human melanoma. The melanomas are induced by s.c. injection of 4-OH-tamoxifen (OHT). By activating a CreER recombinase expressed from a melanocyte-specific promoter, this treatment induces the loss of the conditional Ink4a/Arf gene in melanocytes. Because the CreER gene itself is also flanked by loxP sites, the activation of CreER also induces the deletion of its own coding sequence and thereby allows melanocyte-specific expression of genes H-ras and P1A, which are located downstream on the same transgene. All melanomas induced in those mice with OHT show activation of the Ras pathway and deletion of gene Ink4a/Arf. In addition, these melanomas express P1A and are recognized by P1A-specific T lymphocytes. This model will allow to characterize the interactions between the immune system and naturally occurring tumors and thereby to optimize immunotherapy approaches targeting a defined tumor antigen. (Cancer Res 2006; 66(6): 3278-86)
Phosphorylation of Nucleotide Excision Repair Factor Xeroderma Pigmentosum Group A by Ataxia Telangiectasia Mutated and Rad3-Related–Dependent Checkpoint Pathway Promotes Cell Survival in Response to UV Irradiation
Authors: Wu Xiaoming , Shell Steven M. , Yang Zhengguan , Zou Yue 
Published: March 2006

Abstract
DNA damage triggers complex cellular responses in eukaryotic cells, including initiation of DNA repair and activation of cell cycle checkpoints. In addition to inducing cell cycle arrest, checkpoint also has been suggested to modulate a variety of other cellular processes in response to DNA damage. In this study, we present evidence showing that the cellular function of xeroderma pigmentosum group A (XPA), a major nucleotide excision repair (NER) factor, could be modulated by checkpoint kinase ataxia-telangiectasia mutated and Rad3-related (ATR) in response to UV irradiation. We observed the apparent interaction and colocalization of XPA with ATR in response to UV irradiation. We showed that XPA was a substrate for in vitro phosphorylation by phosphatidylinositol-3-kinase–related kinase family kinases whereas in cells XPA was phosphorylated in an ATR-dependent manner and stimulated by UV irradiation. The Ser196 of XPA was identified as a biologically significant residue to be phosphorylated in vivo. The XPA-deficient cells complemented with XPA-S196A mutant, in which Ser196 was substituted with an alanine, displayed significantly higher UV sensitivity compared with the XPA cells complemented with wild-type XPA. Moreover, substitution of Ser196 with aspartic acid for mimicking the phosphorylation of XPA increased the cell survival to UV irradiation. Taken together, our results revealed a potential physical and functional link between NER and the ATR-dependent checkpoint pathway in human cells and suggested that the ATR checkpoint pathway could modulate the cellular activity of NER through phosphorylation of XPA at Ser196 on UV irradiation. (Cancer Res 2006; 66(6): 2997-3005)
Defective p53 Response and Apoptosis Associated with an Ataxia-Telangiectasia–like Phenotype
Authors: Gueven Nuri , Becherel Olivier J. , Birrell Geoff , Chen Philip , DelSal Giannino , Carney James P. , Grattan-Smith Padraic , Lavin Martin F. 
Published: March 2006

Abstract
Ataxia-telangiectasia mutated (ATM), the protein defective in ataxia-telangiectasia, plays a central role in DNA damage response and signaling to cell cycle checkpoints. We describe here a cell line from a patient with an ataxia-telangiectasia–like clinical phenotype defective in the p53 response to radiation but with normal ATM activation and efficient downstream phosphorylation of other ATM substrates. No mutations were detected in ATM cDNA. A normal level of interaction between p53 and peptidyl-prolyl-isomerase Pin1 suggests that posttranslational modification was intact in these cells but operating at reduced level. Defective p53 stabilization was accompanied by defective induction of p53 effector genes and failure to induce apoptosis in response to DNA-damaging agents. Continued association between p53 and murine double minute-2 (Mdm2) occurred in irradiated ATL2ABR cells in response to DNA damage, and incubation with Mdm2 antagonists, nutlins, increased the stabilization of p53 and its transcriptional activity but failed to induce apoptosis. These results suggest that ATM-dependent stabilization of p53 and induction of apoptosis by radiation involve an additional factor(s) that is defective in ATL2ABR cells. (Cancer Res 2006; 66(6): 2907-12)