bluuebunny/crossref_metadata_2025_split huggingface dataset:
HER-2/neu Status Is a Determinant of Mammary Aromatase Activity In vivo: Evidence for a Cyclooxygenase-2-Dependent Mechanism
Authors: Subbaramaiah Kotha , Howe Louise R. , Port Elisa R. , Brogi Edi , Fishman Jack , Liu Catherine H. , Hla Timothy , Hudis Clifford , Dannenberg Andrew J. 
Published: May 2006

Abstract
Cytochrome P450 aromatase (aromatase), a product of the CYP19 gene, catalyzes the synthesis of estrogens from androgens. Given the significance of estrogen synthesis in hormone-dependent breast carcinogenesis, it is important to elucidate the mechanisms that regulate CYP19 expression. The main objective of this study was to define the interrelationship between HER-2/neu, cyclooxygenase-2 (COX-2), and aromatase in mammary tissue. Mammary aromatase activity and prostaglandin E2 (PGE2) levels were increased in mice with mammary-targeted expression of a COX-2 transgene. In vitro, overexpressing COX-2 caused both increased PGE2 production and aromatase activity, effects that were suppressed by celecoxib, a selective COX-2 inhibitor. Previously, we found that overexpression of HER-2/neu was associated with increased levels of COX-2 in human breast cancers. Here, we show that overexpression of HER-2/neu is also associated with increased aromatase activity. These results suggested the possibility that COX-2 was the functional intermediate linking HER-2/neu and aromatase. Consistent with this idea, COX-2 deficiency led to a gene dose-dependent reduction in mammary aromatase activity in a HER-2/neu transgenic mouse model. Complementary in vitro studies showed that HER-2/neu–mediated induction of PGE2 synthesis and aromatase activity were suppressed by inhibiting COX-2. Collectively, our data indicate that COX-2 is the functional intermediate linking HER-2/neu and aromatase and suggest that inhibitors of PGE2 synthesis will suppress estrogen biosynthesis in breast tissue. (Cancer Res 2006; 66(10): 5504-11)
KRASD13 Promotes Apoptosis of Human Colorectal Tumor Cells by ReovirusT3D and Oxaliplatin but not by Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand
Authors: Smakman Niels , van den Wollenberg Diana J.M. , Elias Sjoerd G. , Sasazuki Takehiko , Shirasawa Senji , Hoeben Rob C. , Borel Rinkes Inne H.M. , Kranenburg Onno 
Published: May 2006

Abstract
Colorectal tumors frequently contain activating mutations in KRAS. ReovirusT3D is an oncolytic virus that preferentially kills tumor cells with an activated Ras pathway. Here we have assessed the contribution of endogenous mutant KRAS in human colorectal cancer cell lines to ReovirusT3D replication and to tumor cell oncolysis. In addition, treatment combinations involving ReovirusT3D, oxaliplatin, and tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) were tested for their efficacy in tumor cell killing. The mutation status of KRAS did not predict the sensitivity of a panel of human colorectal cancer cell lines to ReovirusT3D. Virus replication was observed in all cell lines tested regardless of KRAS status and was not affected by deletion of endogenous mutant KRASD13. However, deletion of KRASD13 or p53 did reduce apoptosis induction by ReovirusT3D whereas deletion of β-cateninΔS45 had no effect. Likewise, KRASD13- or p53-deficient cells display reduced sensitivity to oxaliplatin but not to death receptor activation by TRAIL. Finally, the treatment of colorectal cancer cells with ReovirusT3D combined with either oxaliplatin or TRAIL resulted in a nonsynergistic increase in tumor cell killing. We conclude that oncolysis of human tumor cells by ReovirusT3D is not determined by the extent of virus replication but by their sensitivity to apoptosis induction. Oncogenic KRASD13 increases tumor cell sensitivity to activation of the cell-intrinsic apoptosis pathway without affecting ReovirusT3D replication. (Cancer Res 2006; 66(10): 5403-8)
Malignant Transformation of Immortalized HaCaT Keratinocytes through Deregulated Nuclear Factor κB Signaling
Authors: Ren Qing , Kari Csaba , Quadros Marlene R.D. , Burd Randy , McCue Peter , Dicker Adam P. , Rodeck Ulrich 
Published: May 2006

Abstract
Previous studies addressing functional aspects of nuclear factor κB (NF-κB) activation in normal and transformed keratinocytes revealed complex and seemingly contradictory roles of this transcription factor in this cell type. In normal skin, NF-κB signaling seems to inhibit squamous cell carcinoma development whereas, in squamous cell carcinoma themselves, deregulated NF-κB expression and/or signaling is frequently observed. To further investigate this paradox, we focused on NF-κB activation as it relates to the transformed phenotype of immortalized but nontumorigenic human keratinocytes (HaCaT cells). We observed that NF-κB activity contributed to survival and growth of cultured HaCaT keratinocytes as shown by use of pharmacologic NF-κB inhibitors, RNA interference, and inducible overexpression of a dominant interfering IκB construct. NF-κB activation was largely provided through interaction with extracellular matrix components because preventing cell attachment by forced suspension culture markedly reduced NFκB signaling associated with cell death (anoikis); conversely, anoikis was partially reversed by NF-κB activation induced either by tumor necrosis factor-α treatment or by overexpressing the NF-κB p65 subunit in HaCaT cells. Furthermore, overexpression of NF-κBp65 in HaCaT cells induced colony formation in soft agar and tumorigenicity in nude mice. In summary, as opposed to normal keratinocytes, immortalized HaCaT keratinocytes provide a cellular context in which deregulated NF-κB signaling supports multiple malignant traits in vitro and in vivo. (Cancer Res 2006; 66(10): 5209-15)
BRCC36 Is Essential for Ionizing Radiation–Induced BRCA1 Phosphorylation and Nuclear Foci Formation
Authors: Chen Xiaowei , Arciero Cletus A. , Wang Chunrong , Broccoli Dominique , Godwin Andrew K. 
Published: May 2006

Abstract
We have previously reported the identification and characterization of a novel BRCA1/2 interacting protein complex, BRCC (BRCA1/2-containing complex). BRCC36, one of the proteins in BRCC, directly interacts with BRCA1, and regulates the ubiquitin E3 ligase activity of BRCC. Importantly, BRCC36 is aberrantly expressed in the vast majority of breast tumors, indicating a potential role in the pathogenesis of this disease. To further elucidate the functional consequence of abnormal BRCC36 expression in breast cancer, we have done in vivo silencing studies using small interfering RNAs targeting BRCC36 in breast cancer cell lines, i.e., MCF-7, ZR-75-1, and T47D. Knock-down of BRCC36 alone does not affect cell growth, but when combined with ionizing radiation (IR) exposure, it leads to an increase in the percentage of cells undergoing apoptosis when compared with the small interfering RNA control group in breast cancer cells. Immunoblot analysis shows that inhibition of BRCC36 has no effect on the activation of ATM, expression of p21 and p53, or BRCA1-BARD1 interaction following IR exposure. Importantly, BRCC36 depletion disrupts IR-induced phosphorylation of BRCA1. Immunofluorescent staining of BRCA1 and γ-H2AX indicates that BRCC36 depletion prevents the formation of BRCA1 nuclear foci in response to DNA damage in breast cancer cells. These results show that down-regulation of BRCC36 expression impairs the DNA repair pathway activated in response to IR by inhibiting BRCA1 activation, thereby sensitizing breast cancer cells to IR-induced apoptosis. (Cancer Res 2006; 66(10): 5039-46)
Histone Deacetylase Inhibitors Suppress the Inducibility of Nuclear Factor-κB by Tumor Necrosis Factor-α Receptor-1 Down-regulation
Authors: Imre Gabriele , Gekeler Volker , Leja Astrid , Beckers Thomas , Boehm Markus 
Published: May 2006

Abstract
Recently, the inhibition of histone deacetylase (HDAC) enzymes has attracted attention in the oncologic community as a new therapeutic opportunity for hematologic and solid tumors including non–small cell lung cancer (NSCLC). In hematologic malignancies, such as diffuse large B-cell lymphoma, the HDAC inhibitor (HDI), suberoylanilide hydroxamic acid (SAHA), has recently entered phase II and III clinical trials. To further advance our understanding of their action on tumor cells, we investigated the possible effect of HDI treatment on the functionality of the nuclear factor-κB (NF-κB) pathway in NSCLC. We found that in the NSCLC cell lines, A549 and NCI-H460, the NF-κB pathway was strongly inducible, for example, by stimulation with tumor necrosis factor-α (TNF-α). Incubation of several NSCLC cell lines with HDIs resulted in greatly reduced gene expression of TNF-α receptor-1. HDI-treated A549 and NCI-H460 cells down-regulated TNF-α receptor-1 mRNA and protein levels as well as surface exposure, and consequently responded to TNF-α treatment with reduced IKK phosphorylation and activation, delayed IκB-α phosphorylation, and attenuated NF-κB nuclear translocation and DNA binding. Accordingly, stimulation of NF-κB target gene expression by TNF-α was strongly decreased. In addition, we observed that SAHA displayed antitumor efficacy in vivo against A549 xenografts grown on nude mice. HDIs, therefore, might beneficially contribute to tumor treatment, possibly by reducing the responsiveness of tumor cells to the TNF-α-mediated activation of the NF-κB pathway. These findings also hint at a possible use of HDIs in inflammatory diseases, which are associated with the overproduction of TNF-α, such as rheumatoid arthritis or Crohn's disease. (Cancer Res 2006; 66(10): 5409-18)
Mammary Gland Tissue Targeted Overexpression of Human Protease-Activated Receptor 1 Reveals a Novel Link to β-Catenin Stabilization
Authors: Yin Yong-Jun , Katz Vered , Salah Zaidoun , Maoz Myriam , Cohen Irit , Uziely Beatrice , Turm Hagit , Grisaru-Granovsky Sorina , Suzuki Hiromu , Bar-Shavit Rachel 
Published: May 2006

Abstract
Protease-activated receptor 1 (PAR1) is emerging with distinct assignments in tumor biology. We show that tissue targeted overexpression of hPar1 in mice mammary glands results in precocious hyperplasia, characterized by a dense network of ductal side branching and accelerated proliferation. These glands exhibit increased levels of wnt-4 and wnt-7b and a striking β-catenin stabilization. Nuclear localization of β-catenin is observed in hPar1 transgenic mouse tissue sections but not in the wild-type, age-matched counterparts. PAR1 induces β-catenin nuclear localization also in established epithelial tumor cell lines of intact β-catenin system (transformed on the background of mismatch repair system; RKO cells). We propose hereby that PAR1-mediated β-catenin stabilization is taking place primarily via the increase of Wnt expression. Enforced expression of a specific Wnt antagonist family member, secreted frizzled receptor protein 5 (SFRP5), efficiently inhibited PAR1-induced β-catenin stabilization. Likewise, application of either SFRP2 or SFRP5 on epithelial tumor cells completely abrogated PAR1-induced β-catenin nuclear accumulation. This takes place most likely via inhibition of Wnt signaling at the level of cell surface (forming a neutralizing complex of “Receptors-SFRP-Wnt”). Furthermore, depletion of hPar1 by small interfering RNA (siRNA) vectors markedly inhibited PAR1-induced Wnt-4. The striking stabilization of β-catenin, inhibited by SFRPs on one hand and Wnt-4 silencing by hPar1 siRNA on the other hand, points to a novel role of hPar1 in Wnt-mediated β-catenin stabilization. This link between PAR1 and β-catenin may bear substantial implications both in developmental and tumor progression processes. (Cancer Res 2006; 66(10): 5224-32)
Microarray-Assisted Pathway Analysis Identifies Mitogen-Activated Protein Kinase Signaling as a Mediator of Resistance to the Green Tea Polyphenol Epigallocatechin 3-Gallate in Her-2/neu–Overexpressing Breast Cancer Cells
Authors: Guo Shangqin , Lu Jun , Subramanian Aravind , Sonenshein Gail E. 
Published: May 2006

AbstractOverexpression of the epidermal growth factor receptor family member Her-2/neu in breast cancer leads to autophosphorylation of the receptor and induction of multiple downstream signaling pathways, including the Akt kinase to nuclear factor-κB (NF-κB) cascade that is associated with poor prognosis. Previously, we showed that the green tea polyphenol epigallocatechin 3-gallate (EGCG) inhibits growth of NF639 Her-2/neu–driven breast cancer cells via reducing receptor autophosphorylation and downstream Akt and NF-κB activities. Interestingly, upon prolonged culture in the presence of EGCG, cells resistant to the polyphenol could be isolated. Here, we report that resistant cells have lost tyrosine phosphorylation on the Her-2/neu receptor. Surprisingly, they displayed elevated NF-κB activity, and inhibition of this activity sensitized cells to EGCG. Data from microarray studies of the original and resistant NF639 populations of cells were subjected to Gene Set Enrichment Analysis pathway assessment, which revealed that the mitogen activated protein kinase (MAPK) pathway was activated in the resistant cells. Treatment of the resistant cells with the MAPK inhibitor U0216 reduced growth in soft agar and invasive phenotype, whereas the combination of EGCG and U0216 resulted in cells with a cobblestone epithelial phenotype. Thus, activation of the MAPK pathway mediates resistance to EGCG. (Cancer Res 2006; 66(10): 5322-9)
Antiangiogenic Antithrombin Induces Global Changes in the Gene Expression Profile of Endothelial Cells
Authors: Zhang Weiqing , Chuang Yung-Jen , Jin Tianquan , Swanson Richard , Xiong Yan , Leung Lawrence , Olson Steven T. 
Published: May 2006

AbstractAntithrombin, a serpin family protease inhibitor crucial to hemostasis, acquires antiangiogenic properties on undergoing conformational alterations induced by limited proteolysis or elevated temperature. To better understand the biochemical mechanisms underlying antithrombin antiangiogenic activity, we did genome-wide expression profiling, coupled with quantitative reverse transcription-PCR, Northern blot, and Western blot analyses, to characterize the gene expression patterns that are induced by antiangiogenic antithrombin in cultured primary human umbilical vein endothelial cells. Overall, 35 genes with significantly increased expression and 93 genes with significantly reduced expression (≥2-fold changes) due to antiangiogenic antithrombin treatment were identified. More than half of the down-regulated genes have well-established proangiogenic functions in endothelial cells, including cell-surface and matrix proteoglycans (e.g., perlecan, biglycan, and syndecans 1 and 3) and mitogenesis-related signaling proteins (e.g., mitogen-activated protein kinase 3, signal transducers and activators of transcription 2, 3, and 6, and early growth response factor 1). In contrast, most up-regulated genes (e.g., caspase-3, p21, tissue inhibitor of metalloproteinases 1, 2, and 3, and adenomatosis polyposis coli) are known for their antiangiogenic functions which include the promotion of cell apoptosis and cell cycle arrest and the inhibition of tumor growth and metastasis. These results show that the antiangiogenic activity of antithrombin is mediated at least in part by a global genetic reprogramming of endothelial cells and strongly implicate an endothelial cell ligand-receptor signaling mechanism in this reprogramming. (Cancer Res 2006; 66(10): 5047-55)
Tight Junction Protein Claudin-1 Enhances the Invasive Activity of Oral Squamous Cell Carcinoma Cells by Promoting Cleavage of Laminin-5 γ2 Chain via Matrix Metalloproteinase (MMP)-2 and Membrane-Type MMP-1
Authors: Oku Naohisa , Sasabe Eri , Ueta Eisaku , Yamamoto Tetsuya , Osaki Tokio 
Published: May 2006

AbstractAlthough adherent junctions have been extensively studied, the role of tight junctions in cancer cell invasion is not sufficiently explored. We investigated whether claudin-1, a component of tight junctions, regulated invasion activity in oral squamous cell carcinoma (OSC) cells. The expression of claudin-1, activity of matrix metalloproteinase (MMP)-2, and cleavage of laminin-5 γ2 chains were assessed by Western blot analysis, immunohistochemistry, and zymography in OSC cell lines (OSC-4 and NOS-2, highly invasive; OSC-7, weakly invasive) and their xenografts in severe combined immunodeficient (SCID) mice. The influence of claudin-1 small interfering RNA (siRNA) on the invasion activity of the cell lines was also investigated. Compared with OSC-7, both OSC-4 and NOS-2 more strongly expressed claudin-1 and possessed high activities of MMP-2 and MMP-9. Tumors formed in the tongues of SCID mice xenografted with OSC-4, NOS-2, and OSC-7 immunohistochemically revealed strong, moderate, and weak expression of laminin-5 γ2 chains, respectively, and laminin-5 γ2 chains were secreted in the conditioned medium of the cancer cells in parallel with the in vivo results. Claudin-1 siRNA largely suppressed the invasion of OSC-4 and decreased the activation of MMP-2, the expression of membrane-type MMP-1 (MT1-MMP), and the cleavage of laminin-5 γ2. In addition, not only antibodies against MT1-MMP and epidermal growth factor receptor (EGFR) but also MMP-2 and EGFR inhibitors strongly suppressed the invasion activity of OSC-4. These results suggest that claudin-1 up-regulates cancer cell invasion activity through activation of MT1-MMP and MMP-2, which results in enhanced cleavage of laminin-5 γ2 chains. (Cancer Res 2006; 66(10): 5271-7)
Regulation of Microtubule-Dependent Protein Transport by the TSC2/Mammalian Target of Rapamycin Pathway
Authors: Jiang Xiuyun , Yeung Raymond S. 
Published: May 2006

Abstract
Protein transport plays a critical role in the interaction of the cell with its environment. Recent studies have identified TSC1 and TSC2, two tumor suppressor genes involved in tuberous sclerosis complex, as regulators of the mammalian target of rapamycin (mTOR) pathway. Cells deficient in TSC1 or TSC2 possess high levels of Rheb-GTP resulting in constitutive mTOR activation. We have shown previously that the TSC1/TSC2 complex is involved in post-Golgi transport of VSVG and caveolin-1 in mammalian cells. Here, we show that modulation of mTOR activity affects caveolin-1 localization and that this effect is independent of p70S6K. Tsc1- and Tsc2-null cells exhibit abnormal caveolin-1 localization that is accompanied by disorganized microtubules in the subcortical region. Analyses of green fluorescent protein-EB1 and tubulin in live mutant cells suggest a failure of the plus-ends to sense cortical signals and to halt microtubule growth. Down-regulation of CLIP-170, a putative mTOR substrate with microtubule-binding properties, rescued the abnormal microtubule arrangement and caveolin-1 localization in Tsc2−/− cells. Together, these findings highlight a novel role of the TSC2/mTOR pathway in regulating microtubule-dependent protein transport. (Cancer Res 2006; 66(10): 5258-69)
Inhibition of Tumor Growth and Elimination of Multiple Metastases in Human Prostate and Breast Xenografts by Systemic Inoculation of a Host Defense–Like Lytic Peptide
Authors: Papo Niv , Seger Dalia , Makovitzki Arik , Kalchenko Vyacheslav , Eshhar Zelig , Degani Hadassa , Shai Yechiel 
Published: May 2006

AbstractWe report on a short host defense–like peptide that targets and arrests the growth of aggressive and hormone-resistant primary human prostate and breast tumors and prevents their experimental and spontaneous metastases, respectively, when systemically inoculated to immuodeficient mice. These effects are correlated with increased necrosis of the tumor cells and a significant decrease in the overall tumor microvessel density, as well as newly formed capillary tubes and prostate-specific antigen secretion (in prostate tumors). Growth inhibition of orthotopic tumors derived from stably transfected highly fluorescent human breast cancer cells and prevention of their naturally occurring metastases were visualized in real time by using noninvasive whole-body optical imaging. The exclusive selectivity of the peptide towards cancer derives from its specific binding to surface phosphatidylserine and the killing of the cancer cells via cytoplasmic membrane depolarization. These data indicate that membrane disruption can provide a therapeutic means of inhibiting tumor growth and preventing metastases of various cancers. (Cancer Res 2006; 66(10): 5371-8)
Identification of a Novel Germ Line Variant Hotspot Mutant p53-R175L in Pediatric Adrenal Cortical Carcinoma
Authors: West Alina Nico , Ribeiro Raul C. , Jenkins Jesse , Rodriguez-Galindo Carlos , Figueiredo Bonald C. , Kriwacki Richard , Zambetti Gerard P. 
Published: May 2006

Abstract
Hotspot mutations in the p53 tumor suppressor gene result in the disruption of DNA contact points or alter the overall structure of the protein to prevent DNA binding. When inherited, hotspot mutants are associated with Li-Fraumeni syndrome (LFS), a familial cancer predisposition. One of the most common hotspot mutations occurs at codon 175, resulting in an arginine to histidine substitution. We have identified a novel germ line variant of the 175 mutant (Arg to Leu; R175L) in a pediatric patient who developed adrenal cortical carcinoma. Surprisingly, the family is not tumor prone or associated with LFS. In vitro, the R175L mutant displayed an attenuated tumor suppressor activity in the regulation of transcription, colony formation, and apoptosis when compared with wild-type p53 and the R175H mutant. These findings suggest that p53-R175L retains sufficient activity to suppress LFS, but not adrenal cortical carcinoma. Therefore, not all hotspot mutants are functionally equivalent and the biochemical nature of the mutant may significantly influence clinical outcome. The implications of these results for genetic counseling are discussed. (Cancer Res 2006; 66(10): 5056-62)
Selective Expansion of Marginal Zone B Cells in Eμ-API2-MALT1 Mice Is Linked to Enhanced IκB Kinase γ Polyubiquitination
Authors: Baens Mathijs , Fevery Sabine , Sagaert Xavier , Noels Heidi , Hagens Sofie , Broeckx Vicky , Billiau An D. , De Wolf-Peeters Christiane , Marynen Peter 
Published: May 2006

Abstract
The translocation t(11;18)(q21;q21) that generates an API2-MALT1 fusion protein is the most common structural abnormality among the genetic defects reported in mucosa-associated lymphoid tissue (MALT)-type lymphomas, and its presence correlates with the apparent lack of further genetic instability or chromosomal imbalances. Hence, constitutive nuclear factor-κB (NF-κB) activation induced by the API2-MALT1 fusion protein is considered essential for B-cell transformation. To examine its role in B-cell development and lymphomagenesis, Eμ-API2-MALT1 transgenic mice were produced. Our data show that expression of the API2-MALT1 fusion protein alone is not sufficient for the development of lymphoma masses within 50 weeks. Nevertheless, API2-MALT1 expression affected B-cell maturation in the bone marrow and triggered the specific expansion of splenic marginal zone B cells. Polyubiquitination of IκB kinase γ (IKKγ), indicative for enhanced NF-κB activation, was increased in splenic lymphocytes and promoted the survival of B cells ex vivo. In addition, we show that the API2-MALT1 fusion resided in the cholesterol- and sphingolipid-enriched membrane microdomains, termed lipid rafts. We provide evidence that association of the MALT1 COOH terminal with the lipid rafts, which is mediated by the API2 portion, is sufficient to trigger NF-κB activation via enhanced polyubiquitination of IKKγ. Taken together, these data support the hypothesis that the API2-MALT1 fusion protein can contribute to MALT lymphoma formation via increased NF-κB activation. (Cancer Res 2006; 66(10): 5270-7)