bluuebunny/crossref_metadata_2025_split huggingface dataset:
EGFRvIII and c-Met pathway inhibitors synergize against PTEN-null/EGFRvIII+ glioblastoma xenografts
Authors: Lal Bachchu , Goodwin C. Rory , Sang Yingying , Foss Catherine A. , Cornet Kathrine , Muzamil Sameena , Pomper Martin G. , Kim Jin , Laterra John 
Published: July 2009

Abstract
Receptor tyrosine kinase (RTK) systems, such as hepatocyte growth factor (HGF) and its receptor c-Met, and epidermal growth factor receptor (EGFR), are responsible for the malignant progression of multiple solid tumors. Recent research shows that these RTK systems comodulate overlapping and dynamically adaptable oncogenic downstream signaling pathways. This study investigates how EGFRvIII, a constitutively active EGFR deletion mutant, alters tumor growth and signaling responses to RTK inhibition in PTEN-null/HGF+/c-Met+ glioma xenografts. We show that a neutralizing anti-HGF monoclonal antibody (L2G7) potently inhibits tumor growth and the activation of Akt and mitogen-activated protein kinase (MAPK) in PTEN-null/HGF+/c-Met+/EGFRvIII− U87 glioma xenografts (U87wt). Isogenic EGFRvIII+ U87 xenografts (U87-EGFRvIII), which grew five times more rapidly than U87-wt xenografts, were unresponsive to EGFRvIII inhibition by erlotinib and were only minimally responsive to anti-HGF monoclonal antibodies. EGFRvIII expression diminished the magnitude of Akt inhibition and completely prevented MAPK inhibition by L2G7. Despite the lack of response to L2G7 or erlotinib as single agents, their combination synergized to produce substantial antitumor effects (inhibited tumor cell proliferation, enhanced apoptosis, arrested tumor growth, prolonged animal survival), against subcutaneous and orthotopic U87-EGFRvIII xenografts. The dramatic response to combining HGF:c-Met and EGFRvIII pathway inhibitors in U87-EGFRvIII xenografts occurred in the absence of Akt and MAPK inhibition. These findings show that combining c-Met and EGFRvIII pathway inhibitors can generate potent antitumor effects in PTEN-null tumors. They also provide insights into how EGFRvIII and c-Met may alter signaling networks and reveal the potential limitations of certain biochemical biomarkers to predict the efficacy of RTK inhibition in genetically diverse cancers. [Mol Cancer Ther 2009;8(7):1751–60]
Increased antitumor activity of bevacizumab in combination with hypoxia inducible factor-1 inhibition
Authors: Rapisarda Annamaria , Hollingshead Melinda , Uranchimeg Badarch , Bonomi Carrie A. , Borgel Suzanne D. , Carter John P. , Gehrs Bradley , Raffeld Mark , Kinders Robert J. , Parchment Ralph , Anver Miriam R. , Shoemaker Robert H. , Melillo Giovanni 
Published: July 2009

AbstractInhibition of hypoxia inducible factor-1 (HIF-1) is an attractive therapeutic strategy to target the tumor microenvironment. However, HIF-1 inhibitors may have limited activity as single agents and combination therapies may be required. We tested the hypothesis that HIF-1 inhibition in a hypoxic-stressed tumor microenvironment, which could be generated by administration of antiangiogenic agents, may result in a more pronounced therapeutic effect. The activity of bevacizumab, either alone or in combination with the HIF-1α inhibitor topotecan, was evaluated in U251-HRE xenografts. Tumor tissue was collected at the end of treatment and changes in tumor oxygenation, angiogenesis, proliferation, apoptosis, HIF-1α levels, HIF-1 target genes, and DNA damage were evaluated. Bevacizumab decreased microvessel-density and increased intratumor-hypoxia, but did not induce apoptosis. Moreover, bevacizumab alone caused a significant increase of HIF-1–dependent gene expression in tumor tissue. Addition of a low dose of daily topotecan to bevacizumab significantly inhibited tumor growth, relative to mice treated with topotecan or bevacizumab alone (P &lt; 0.01). The addition of topotecan to bevacizumab was also associated with profound inhibition of HIF-1 transcriptional activity, significant inhibition of proliferation, and induction of apoptosis. Importantly, DNA damage induced by topotecan alone was not augmented by addition of bevacizumab, suggesting that increased cytotoxic activity did not account for the increased antitumor effects observed. These results strongly suggest that combination of anti–vascular endothelial growth factor antibodies with HIF-1 inhibitors is an attractive therapeutic strategy targeting in the hypoxic tumor microenvironment. [Mol Cancer Ther 2009;8(7):1867–77]
Pertuzumab increases epidermal growth factor receptor down-regulation by counteracting epidermal growth factor receptor-ErbB2 heterodimerization
Authors: Hughes Juliana Bentes , Berger Christian , Rødland Marianne Skeie , Hasmann Max , Stang Espen , Madshus Inger Helene 
Published: July 2009

Abstract
Epidermal growth factor receptor (EGFR) and ErbB2 readily form heterodimers when both are expressed in the same cell and the EGFR is activated by one of its ligands. Our data show that such heterodimers are constitutively formed also in a ligand-independent manner on overexpression of EGFR and ErbB2 in porcine aortic endothelial cells. Interestingly, cross-linking experiments showed that incubation with the antibody pertuzumab, which has been shown to bind the dimerization arm of ErbB2, resulted in dissolution of EGFR-ErbB2 heterodimers. Incubation with pertuzumab also increased the amount of EGF-induced EGFR homodimers, and under these conditions, endocytosis of radiolabeled EGF was increased. This increase was significant, although slightly more EGF was internalized in cells expressing EGFR only compared with pertuzumab-treated cells expressing both EGFR and ErbB2. By confocal microscopy analysis, more EGF was observed in endosomes on incubation with pertuzumab, and under similar conditions, immunoblotting experiments showed increased EGFR degradation on incubation with both EGF and pertuzumab. These results show that pertuzumab enhanced the endocytic down-regulation of EGFR by counteracting EGFR-ErbB2 heterodimerization. Our previous results showing that ErbB2 counteracts EGFR endocytosis can therefore be explained by tethering of EGFR to ErbB2 at the plasma membrane. [Mol Cancer Ther 2009;8(7):1885–92]
Induction of glutathione-dependent DNA double-strand breaks by the novel anticancer drug brostallicin
Authors: Guirouilh-Barbat Josée , Zhang Yong-Wei , Pommier Yves 
Published: July 2009

Abstract
Brostallicin is a DNA minor groove binder in phase II clinical trials. Here, we show that brostallicin induces γ-H2AX nuclear foci that colocalize with 53BP1 and are dependent on glutathione, as shown by inhibition of those γ-H2AX foci by l-buthionine sulfoximine. To differentiate brostallicin from the clinically approved minor groove binder trabectedin (ecteinascidin 743), we tested whether the brostallicin-induced γ-H2AX and antiproliferative responses were dependent on nucleotide excision repair and found that, unlike trabectedin, they are not. Additionally, brostallicin retained activity in the trabectedin-resistant HCT116-ER5 cell line. Induction of γ-H2AX foci by brostallicin was partially dependent on the repair nuclease Mre11. Pretreatment with aphidicolin partially reduced brostallicin-induced γ-H2AX foci, suggesting that brostallicin induces both replication-associated and replication-independent DNA damage. Replication-associated DNA damage was further shown by the colocalization of γ-H2AX foci with replication foci and by the rapid inhibition of DNA synthesis and accumulation of cells in S phase in response to brostallicin. In addition, brostallicin was able to induce lower intensity γ-H2AX foci in human circulating lymphocytes. Together, our results indicate that brostallicin induces DNA double-strand breaks and suggest γ-H2AX as a pharmacodynamic biomarker for brostallicin. [Mol Cancer Ther 2009;8(7):1985–94]
Determinants for the efficiency of anticancer drugs targeting either Aurora-A or Aurora-B kinases in human colon carcinoma cells
Authors: Kaestner Phillip , Stolz Ailine , Bastians Holger 
Published: July 2009

AbstractThe mitotic Aurora kinases, including Aurora-A and Aurora- B, are attractive novel targets for anticancer therapy, and inhibitory drugs have been developed that are currently undergoing clinical trials. However, the molecular mechanisms how these drugs induce tumor cell death are poorly understood. We have addressed this question by comparing the requirements for an efficient induction of apoptosis in response to MLN8054, a selective inhibitor of Aurora-A, and the selective Aurora-B inhibitor ZM447439 in human colon carcinoma cells. By using various isogenic knockout as well as inducible colon carcinoma cell lines, we found that treatment with MLN8054 induces defects in mitotic spindle assembly, which causes a transient spindle checkpoint–dependent mitotic arrest. This cell cycle arrest is not maintained due to the activity of MLN8054 to override the spindle checkpoint. Subsequently, MLN8054-treated cells exit from mitosis and activate a p53-dependent postmitotic G1 checkpoint, which subsequently induces p21 and Bax, leading to G1 arrest followed by the induction of apoptosis. In contrast, inhibition of Aurora-B by ZM447439 also interferes with normal chromosome alignment during mitosis and overrides the mitotic spindle checkpoint but allows a subsequent endoreduplication, although ZM447439 potently activates the p53-dependent postmitotic G1 checkpoint. Moreover, the ZM447439-induced endoreduplication is a prerequisite for the efficiency of the drug. Thus, our results obtained in human colon carcinoma cells indicate that although both Aurora kinase inhibitors are potent inducers of tumor cell death, the pathways leading to the induction of apoptosis in response to these drugs are distinct. [Mol Cancer Ther 2009;8(7):2046–56]
Zalypsis (PM00104) is a potent inducer of γ-H2AX foci and reveals the importance of the C ring of trabectedin for transcription-coupled repair inhibition
Authors: Guirouilh-Barbat Josée , Antony Smitha , Pommier Yves 
Published: July 2009

Abstract
Zalypsis (PM00104) is a novel tetrahydroisoquinoline alkaloid related to trabectedin [ecteinascidin 743 (Et743)]. Et743 and PM00104 have similar A and B rings but differ in their C rings. The present study shows that Et743 and PM00104 differ in at least two ways: in their DNA binding properties and nucleotide excision repair (NER) dependency for cellular targeting. DNase I footprinting shows that the two drugs bind DNA differentially. We also found that, in contrast to Et743, the antiproliferative activity of PM00104 does not depend on transcription-coupled NER. Accordingly, PM00104 induces γ-H2AX foci with the same efficiency in NER-deficient or NER-proficient cells. Moreover, the formation of γ-H2AX foci is replication dependent for PM00104, whereas it is both transcription and replication dependent in the case of Et743. These findings show the importance of the C ring structure of tetrahydroisoquinoline ecteinascidin derivatives for NER targeting. Finally, PM00104 exerts antiproliferative activity at nanomolar concentrations and induces γ-H2AX response in two Ewing's sarcoma cell lines, suggesting that γ-H2AX could serve as a pharmacodynamic biomarker for the clinical development of PM00104. [Mol Cancer Ther 2009;8(7):2007–14]
Nuclear Factor-κB Inhibition by Parthenolide Potentiates the Efficacy of Taxol in Non–Small Cell Lung Cancer In vitro and In vivo
Authors: Zhang Dianliang , Qiu Lin , Jin Xianqing , Guo Zhenhua , Guo Chunbao 
Published: July 2009

Abstract
In this study, we have examined the molecular events induced by parthenolide, a sesquiterpene lactone, and explored possible mechanisms of resistance and sensitization of tumor cells to Taxol. We showed that parthenolide could antagonize Taxol-mediated nuclear factor-κB (NF-κB) nuclear translocation and activation and Bcl-xl up-regulation by selectively targeting I-κB kinase activity. In A549 cells, inhibition of nuclear factor-κB by parthenolide resulted in activation of the mitochondrial death pathway to promote cytochrome c release and caspase 3 and 9 activation. In contrast, Taxol alone induced apoptosis via a pathway independent of mitochondria cytochrome c cascade. In addition, depletion of Bcl-xl rescued the apoptotic response to Taxol. Moreover, treatment with parthenolide increased the efficacy of the Taxol-induced inhibition of A549 tumor xenografts in mice. This study elucidated the cellular responses induced by parthenolide that decrease the threshold of mitochodria-dependent apoptosis in the treatment of non–small cell lung cancer cells. (Mol Cancer Res 2009;7(7):1139–49)
Therapeutic Inhibition of the Epidermal Growth Factor Receptor in High-Grade Gliomas: Where Do We Stand?
Authors: Karpel-Massler Georg , Schmidt Ursula , Unterberg Andreas , Halatsch Marc-Eric 
Published: July 2009

AbstractHigh-grade gliomas account for the majority of intra-axial brain tumors. Despite abundant therapeutic efforts, clinical outcome is still poor. Thus, new therapeutic approaches are intensely being investigated. Overexpression of the epidermal growth factor receptor (HER1/EGFR) is found in various epithelial tumors and represents one of the most common molecular abnormalities seen in high-grade gliomas. Dysregulated HER1/EGFR is found in 40% to 50% of glioblastoma, the most malignant subtype of glioma. Several agents such as tyrosine kinase (TK) inhibitors, antibodies, radio-immuno conjugates, ligand-toxin conjugates, or RNA-based agents have been developed to target HER1/EGFR or its mutant form, EGFRvIII. To date, most agents are in various stages of clinical development. Clinical data are sparse but most advanced for TK inhibitors. Although data from experimental studies seem promising, proof of a significant clinical benefit is still missing. Among the problems that have to be further addressed is the prediction of the individual patient's response to HER1/EGFR-targeted therapeutics based on molecular determinants. It is quite possible that blocking HER1/EGFR alone will not sufficiently translate into a clinical benefit. Therefore, a multiple target approach concomitantly aimed at different molecular sites might be a favorable concept. This review focuses on current HER1/EGFR-targeted therapeutics and their development for high-grade gliomas. (Mol Cancer Res 2009;7(7):1000–12)
Cyclooxygenase-2 Up-Regulates Ataxia Telangiectasia and Rad3 Related through Extracellular Signal-Regulated Kinase Activation
Authors: Kim Young Mee , Lee Eun Jung , Park Soo-Yeon , Cho Kwan Ho , Kim Joo Young , Pyo Hongryull 
Published: July 2009

Abstract
Cyclooxygenase-2 (COX-2) overexpression caused prolonged G2 arrest after exposure to ionizing radiation (IR) in our previous study. We were therefore interested in investigating the function of COX-2 in the G2 checkpoint pathway. Interestingly, we found that cells in which COX-2 is overexpressed showed up-regulated ataxia telangiectasia and Rad3 related (ATR) expression compared with control cells. In this study, we investigated the mechanism of ATR up-regulation by COX-2 and tested our hypothesis that COX-2–induced extracellular signal-regulated kinase (ERK) activation mediates up-regulation of ATR by COX-2. To investigate the relationship between COX-2 and ATR, we used two stable COX-2–overexpressing cancer cell lines (HCT116–COX-2 and H460–COX-2), a COX-2 knockdown A549 lung cancer cell line (AS), and an ATR knockdown HCT116 cell line. Cells were treated with various drugs [celecoxib, prostaglandin E2 (PGE2), PD98059, U0126, and hydroxyurea] and were then analyzed using reverse transcription-PCR, confocal microscopy, Western blotting, and clonogenic assay. COX-2–overexpressing cells were shown to have increased ERK phosphorylation and ATR expression compared with control cells, whereas AS cells were shown to have decreased levels of phospho-ERK and ATR. In addition, exogenously administered PGE2 increased ERK phosphorylation. Inhibition of ERK phosphorylation decreased ATR expression in both HCT116–COX-2 and A549 cells. HCT116–COX-2 cells were resistant to IR or hydroxyurea compared with HCT116-Mock cells, whereas administration of ATR shRNA showed the opposite effect. COX-2 stimulates ERK phosphorylation via PGE2. This COX-2–induced ERK activation seems to increase ATR expression and activity in endogenous COX-2–overexpressing cancer cells as well as in COX-2–overexpressing stable cell lines. (Mol Cancer Res 2009;7(7):1158–68)
Targeting of Tumor Blood Vessels: A Phage-Displayed Tumor-Homing Peptide Specifically Binds to Matrix Metalloproteinase-2-Processed Collagen IV and Blocks Angiogenesis In vivo
Authors: Mueller Jan , Gaertner Florian C. , Blechert Birgit , Janssen Klaus-Peter , Essler Markus 
Published: July 2009

Abstract
Proteolytic degradation of the basement membrane by the matrix metalloproteinase-2 and -9 is an essential step in tumor angiogenesis. On proteolytic degradation, cryptic sites in collagen IV are formed, which serve as a migration signal for endothelial cells and are specific for angiogenic blood vessels. The aim of this study was to generate peptides that bind specifically to proteolytically processed collagen IV and to test whether these peptides accumulate in tumor vasculature and are able to block angiogenesis. To obtain such peptides, we performed a combined in vivo and in vitro phage display screen using a recombinant phage-displayed peptide library. We found a phage displaying the peptide sequence TLTYTWS that specifically binds to collagen IV modified by matrix metalloproteinase-2. We then tested the ability of the phage to bind to the vasculature in xenograft tumors and found indeed a significant accumulation of the phage in tumors but not in control organs. The tumor homing of the TLTYTWS phage is specific, as it can be blocked by coinjection chemically synthesized cognate peptide. Moreover, TLTYTWS peptide inhibits angiogenesis in an in vivo assay in a concentration-dependent manner and significantly reduces endothelial differentiation in vitro. In conclusion, we report about a novel tumor-homing peptide that specifically binds to proteolytically processed collagen IV, accumulates in tumors, and blocks angiogenesis. This peptide may be a new useful tool for diagnostic and therapeutic procedures in oncology.(Mol Cancer Res 2009;7(7):1078–85)
CXCR4 and Matrix Metalloproteinase-1 Are Elevated in Breast Carcinoma–Associated Fibroblasts and in Normal Mammary Fibroblasts Exposed to Factors Secreted by Breast Cancer Cells
Authors: Eck Sarah M. , Côté Anik L. , Winkelman William D. , Brinckerhoff Constance E. 
Published: July 2009

Abstract
The complex molecular communications that occur between neoplastic and stromal cells within the tumor microenvironment play an integral role in breast cancer pathogenesis. Carcinoma-associated fibroblasts (CAF) produce tumor-enhancing factors and have been strongly implicated in breast cancer development. Similar to the way in which tumors have been compared with “wounds that never heal,” CAFs have been equated to activated fibroblasts, which are present in inflammatory environments, in which they aid in wound healing through tissue remodeling and repair. Matrix metalloproteinase-1 (MMP-1) and G protein–coupled receptor, CXCR4, are elevated in these activated fibroblasts, in which they facilitate angiogenesis and matrix degradation, processes that are also vital to breast cancer metastasis. In this study, we investigated MMP-1 and CXCR4 expression in normal human mammary fibroblasts (HMF) exposed to soluble breast cancer factors. Historically, elevated CXCR4 expression is associated with breast cancer cells. However, we show that soluble factors secreted by SUM102 breast cancer cells stimulated the expression of MMP-1 and CXCR4 in HMFs. As a result, these stromal cells acquired an invasive and migratory phenotype. To confirm the clinical relevancy of our findings, we analyzed CAFs obtained from primary breast cancers. These cells also displayed elevated MMP-1 and CXCR4 levels compared with counterpart fibroblasts, and were more invasive and migratory. Together, our data suggest that soluble breast cancer factors initiate the transdifferentiation of normal HMFs to tumor-promoting CAFs, and that through the induction of MMP-1 and CXCR4 levels, these cells exhibit an invasive and migratory phenotype.(Mol Cancer Res 2009;7(7):1033–44)
Matrix Protein CCN1 Is Critical for Prostate Carcinoma Cell Proliferation and TRAIL-Induced Apoptosis
Authors: Franzen Carrie A. , Chen Chih-Chiun , Todorović Viktor , Juric Vladislava , Monzon Ricardo I. , Lau Lester F. 
Published: July 2009

Abstract
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) plays an important role in immune surveillance and preferentially induces apoptosis in cancer cells over normal cells, suggesting its potential in cancer therapy. However, the molecular basis for its selective killing of cancer cells is not well understood. Recent studies have identified the CCN family of integrin-binding matricellular proteins as important regulators of cell behavior, including cell adhesion, proliferation, migration, differentiation, and survival. We show here that CCN1 (CYR61) supports the adhesion of prostatic carcinoma cells as an adhesion substrate through integrins and heparan sulfate proteoglycans. Knockdown of CCN1 expression in PC-3 and DU-145 androgen-independent prostate cancer cells strongly inhibited their proliferation without causing apoptosis, indicating that CCN1 promotes their growth. However, CCN1 also significantly enhances TRAIL-induced apoptosis through interaction with integrins αvβ3 and α6β4 and the cell-surface heparan sulfate proteoglycan syndecan-4, acting through a protein kinase Cα-dependent mechanism without requiring de novo protein synthesis. Knockdown of CCN1 expression in PC-3, DU-145, and LNCaP cells severely blunted their sensitivity to TRAIL, an effect that was reversed by exogenously added CCN1 protein. These findings reveal a functional dichotomy for CCN1 in prostate carcinoma cells, because it contributes to both cell proliferation and TRAIL-induced cell death and suggest that CCN1 expression status may be an important parameter in assessing the efficacy of TRAIL-dependent cancer therapy. (Mol Cancer Res 2009;7(7):1045–55)
Requirement of Phosphatidylinositol(3,4,5)Trisphosphate in Phosphatidylinositol 3-Kinase-Induced Oncogenic Transformation
Authors: Denley Adam , Gymnopoulos Marco , Kang Sohye , Mitchell Christina , Vogt Peter K. 
Published: July 2009

Abstract
Phosphatidylinositol 3-kinases (PI3K) are divided into three classes, which differ in their substrates and products. Class I generates the inositol phospholipids PI(3)P, PI(3,4)P2, and PI(3,4,5)P3 referred as PIP, PIP2, and PIP3, respectively. Class II produces PIP and PIP2, and class III generates only PIP. Substrate and product differences of the three classes are determined by the activation loops of their catalytic domains. Substitution of the class I activation loop with either class II or III activation loop results in a corresponding change of substrate preference and product restriction. We have evaluated such activation loop substitutions to show that oncogenic activity of class I PI3K is linked to the ability to produce PIP3. We further show that reduction of cellular PIP3 levels by the 5′-phosphatase PIPP interferes with PI3K-induced oncogenic transformation. PIPP also attenuates signaling through Akt and target of rapamycin. Class III PI3K fails to induce oncogenic transformation. Likewise, a constitutively membrane-bound class I PI3K mutant retaining only the protein kinase is unable to induce transformation. We conclude that PIP3 is an essential component of PI3K-mediated oncogenesis and that inability to generate PIP3 abolishes oncogenic potential. (Mol Cancer Res 2009;7(7):1132–8)