bluuebunny/crossref_metadata_2025_split huggingface dataset:
Breast Cancer Cells Can Evade Apoptosis-Mediated Selective Killing by a Novel Small Molecule Inhibitor of Bcl-2
Authors: Real Pedro Jose , Cao Yeyu , Wang Renxiao , Nikolovska-Coleska Zaneta , Sanz-Ortiz Jaime , Wang Shaomeng , Fernandez-Luna Jose Luis 
Published: September 2005

Abstract
Proteins of the Bcl-2 family are key regulators of caspase activation and apoptosis. Some members of this family, notably Bcl-2 and Bcl-xL, are overexpressed in cancer cells, which have been associated with chemoresistance. We have designed and synthesized a small molecule inhibitor of Bcl-2, named YC137, and studied its role in cancer cells. In vitro studies showed that YC137 inhibits the binding of the Bid BH3 peptide to Bcl-2, thus disrupting an interaction essential for the antiapoptotic activity of Bcl-2. This inhibitor induces apoptosis of hematopoietic progenitors overexpressing Bcl-2 but not Bcl-xL and breast cancer cells that express high levels of Bcl-2. On the contrary, a variety of normal primary cells, including CD34+ progenitors, myoblasts, and peripheral blood mononuclear cells, do not respond to the inhibitor. A breast cancer cell line resistant to YC137 was generated. Analysis of resistant cells revealed a reduced expression of Bcl-2, which correlated with low activation of signal transducer and activator of transcription-3 (Stat3) and reduced expression of the human epidermal growth factor receptor-2 (HER2). Of note, YC137-resistant cells were more sensitive to apoptosis induced by chemotherapy. Because HER2 has not been linked previously to the Stat3-Bcl-2 transcriptional pathway, we additionally confirmed that specific blockade of HER2 in breast cancer cells resulted in down-regulation of Stat3 activity and reduced levels of Bcl-2. Consistently, HER2 blockade led to YC137 resistance. These data provide evidence for the selective killing of tumor cells by YC137 and represent the first example of in vitro selection of cancer cells refractory to a Bcl-2 inhibitor.
The Centrosomal Kinase Nek2 Displays Elevated Levels of Protein Expression in Human Breast Cancer
Authors: Hayward Daniel G. , Clarke Robert B. , Faragher Alison J. , Pillai Meenu R. , Hagan Iain M. , Fry Andrew M. 
Published: September 2005

Abstract
Aneuploidy and chromosome instability are common abnormalities in human cancer. Loss of control over mitotic progression, multipolar spindle formation, and cytokinesis defects are all likely to contribute to these phenotypes. Nek2 is a cell cycle-regulated protein kinase with maximal activity at the onset of mitosis that localizes to the centrosome. Functional studies have implicated Nek2 in regulation of centrosome separation and spindle formation. Here, we present the first study of the protein expression levels of the Nek2 kinase in human cancer cell lines and primary tumors. Nek2 protein is elevated 2- to 5-fold in cell lines derived from a range of human tumors including those of cervical, ovarian, breast, prostate, and leukemic origin. Most importantly, by immunohistochemistry, we find that Nek2 protein is significantly up-regulated in preinvasive in situ ductal carcinomas of the breast as well as in invasive breast carcinomas. Finally, by ectopic expression of Nek2A in immortalized HBL100 breast epithelial cells, we show that increased Nek2 protein leads to accumulation of multinucleated cells with supernumerary centrosomes. These data highlight the Nek2 kinase as novel potential target for chemotherapeutic intervention in breast cancer.
Enhanced Redundancy in Akt and Mitogen-activated Protein Kinase-induced Survival of MalignantversusNormal Prostate Epithelial Cells
Authors: Uzgare Aarti R. , Isaacs John T. 
Published: September 2005

AbstractActivation of the downstream akt and mitogen-activated protein kinases is associated with development and progression of prostate cancer to the lethal androgen-independent state. However, the causal role of these downstream kinases in androgen-independent prostate cancers is unknown. In this study, activation and requirements of akt and mitogen-activated protein kinase (erk, p38, and jnk) signaling for the survival and proliferation of five malignant human cell lines encompassing the spectrum of androgen-independent prostate cancers was compared with the activation and requirements in normal prostate epithelial cells. Using Western blotting with phospho-antibodies, we detected differential activation in exponentially growing, growth factor-deprived, and restimulated cultures of malignant versus normal cells. The inhibition of erk, p38, jnk, and akt with U0126, SB203580, SP600125, and Akt inhibitor, respectively, document that normal cells require simultaneous erk and jnk signaling for survival, plus akt signaling for proliferation. In malignant cells, however, only jnk inhibition as monotherapy produces a consistent apoptotic response, although the combinatorial inhibition of jnk, erk, p38 plus akt results in statistically enhanced apoptosis. These results demonstrate that prostate cancer progression to a lethal androgen-independent state involves the acquisition of an enhanced redundancy in downstream survival signaling.
Mechanistic and Predictive Profiling of 5-Fluorouracil Resistance in Human Cancer Cells
Authors: Wang Weiguang , Cassidy James , O’Brien Vincent , Ryan Kevin M. , Collie-Duguid Elaina 
Published: September 2005

Abstract
Gene expression was analyzed in five pairs of 5-fluorouracil (5-FU) resistant and parental cancer cell lines on DNA microarrays. In unsupervised analysis, a prediction rule was built from the expression profiles of 29 genes, and 5-FU sensitivity class was predicted with 100% accuracy and high predictive strength. In supervised analysis of key 5-FU pathways, expression of 91 genes was associated with 5-FU sensitivity phenotype and segregated samples accordingly in hierarchical analysis. Key genes involved in 5-FU activation were significantly down-regulated (thymidine kinase, 2.9-fold; orotate phosphoribosyltransferase, 2.3-fold; uridine monophosphate kinase, 3.2-fold; pyrimidine nucleoside phosphorylase 3.6-fold) in resistant cells. Overexpression of thymidylate synthase and its adjacent gene, c-Yes, was detected in the resistant cell lines. The mRNA and protein overexpression of nuclear factor κB (NFκB) p65 and related antiapoptotic c-Flip gene was detected in resistant cells. The 5-FU-resistant cell lines also showed high NFκB DNA-binding activity. Cotransfection of NFκB p50 and p65 cDNA induced 5-FU resistance in MCF-7 cells. Both NFκB- and 5-FU-induced resistant cell lines manifested reduced expression of genes governing G1-S and S-phase transition. Expression of genes involved in DNA replication was also down-regulated in resistant cell lines. These findings were highly consistent with the slower growth rate, higher proportion of G1, and lower proportion of S-phase cells in the resistant cell lines. This phenotype may protect resistant cells from cell death induced by incorporation of 5-FU into DNA chains, by allowing time to repair 5-FU-induced damage. Our findings may provide novel targets for tackling 5-FU resistance.
Blockade of Paclitaxel-Induced Thymidine Phosphorylase Expression Can Accelerate Apoptosis in Human Prostate Cancer Cells
Authors: Kikuno Nobuyuki , Moriyama-Gonda Nobuko , Yoshino Tateki , Yoneda Tatsuaki , Urakami Shinji , Terashima Masaharu , Yoshida Manabu , Kishi Hirofumi , Shigeno Kazushi , Shiina Hiroaki , Igawa Mikio 
Published: September 2005

Abstract
Recently, survival benefit by chemotherapy using paclitaxel (PTX) and the induction of thymidine phosphorylase (TP) by PTX have been reported in several solid tumors. On the other hand, TP confers antiapoptotic effect on tumor cells through inhibition of caspase-8 activation in vitro. On the basis of these previous observations, we hypothesized that (a) TP can be induced after PTX treatment in human prostate cancer (PC) and (b) blockade of PTX-induced TP expression can enhance the apoptotic processes in human PC cells. PTX was used to find TP expression in all eight hormone-refractory PC cases after chemotherapy; however, cleaved caspase-8 was not expressed after chemotherapy in the six hormone-refractory PC cases with strong TP expression. In PC cell lines (PC-3, DU 145, and LNCaP), TP expression after PTX treatment was clearly up-regulated in a dose-dependent manner. Cell viability of PC cell lines treated with PTX and TP antisense was significantly reduced in a time-dependent and dose-dependent manner compared with the PTX treatment alone. Likewise, apoptotic index of PC cells treated with PTX and TP antisense was significantly increased in comparison with PTX alone. After complete blockade of PTX-induced TP translation by TP antisense transfection, cleaved form of caspase-3 and poly(ADP-ribose) polymerase was increased, and this exaggeration of apoptosis also ran parallel with caspase-8 activation in a PTX dose-dependent manner. However, in PC cell lines treated with TP antisense alone, neither caspase-3 nor poly(ADP-ribose) polymerase was cleaved despite caspase-8 activation. These results indicate that PTX-induced TP up-regulation is associated with decreased caspase-8 activation. This study is the first report showing that blockade of PTX-induced TP expression could exaggerate the processing of apoptosis in PC cells treated with PTX. Our results provide preclinical evidence that TP could be a new molecular target for enhancing the potency of PTX-mediated apoptosis in PC cells.
Hepatocyte Growth Factor/c-Met Signaling Promotes the Progression of Experimental Human Neuroblastomas
Authors: Hecht Monica , Papoutsi Maria , Tran Hoa Dinh , Wilting Joerg , Schweigerer Lothar 
Published: September 2005

Abstract
Neuroblastoma is the most frequent solid childhood malignancy. Despite aggressive therapy, mortality is high due to rapid tumor progression to advanced stages. The molecules and mechanisms underlying poor prognosis are not well understood. Here, we report that cultured human neuroblastoma cells express the hepatocyte growth factor (HGF) and its receptor c-Met. Binding of HGF to c-Met triggers receptor autophosphorylation, indicating functional relevance of this interaction. HGF activates several downstream effectors of c-Met such as the mitogen-activated protein kinases extracellular signal-regulated kinase 1/extracellular signal-regulated kinase 2 and phospholipase C-γ, whereas signal transducer and activator of transcription 3 is constitutively activated in neuroblastoma cells expressing c-Met. In addition, HGF is able to stimulate expression and proteolytic activity of matrix metalloproteinase-2 and tissue-type plasminogen activator in neuroblastoma cells, thereby promoting degradation of extracellular matrix components. We show that HGF stimulates invasion of neuroblastoma cells in vitro and in vivo, and it promotes the formation of angiogenic neuroblastomas in vivo. These processes can be blocked by specific inhibitors of the mitogen-activated protein kinase cascade, by inhibitors of phospholipase C-γ, and also by the expression of a dominant negative signal transducer and activator of transcription 3 mutant. Our data provide the first evidence that the HGF/c-Met pathway is essential for invasiveness and malignant progression of human neuroblastomas. They further suggest that specific inhibitors of this pathway may be suitable as therapeutic agents to improve clinical outcome of neuroblastomas.
An Epidermal Growth Factor Receptor Intron 1 Polymorphism Mediates Response to Epidermal Growth Factor Receptor Inhibitors
Authors: Amador Maria L. , Oppenheimer Darin , Perea Sofia , Maitra Anirban , Cusati George , Iacobuzio-Donahue Christi , Baker Sharyn D. , Ashfaq Raheela , Takimoto Chris , Forastiere Arlene , Hidalgo Manuel 
Published: September 2005

AbstractThis study tested the hypothesis that the number of CA single sequence repeat (CA-SSR) in the intron 1 of the epidermal growth factor receptor (egfr) gene, which affects transcription efficiency of the gene, is associated with the response to EGFR inhibitors. To this end, we determined the number of CA dinucleotides in the intron 1 of the egfr gene in a panel of 12 head and neck cancer cell lines that lack egfr gene amplification and measured the expression of EGFR (mRNA and protein), as well as response to EGFR inhibition. Cells with lower number of CA dinucleotides in the CA-SSR had higher expression of the EGFR gene and protein and were more sensitive to the inhibitory effects of erlotinib, a small molecule inhibitor of the EGFR tyrosine-kinase. Phenotypic modification by silencing EGFR mRNA expression in a susceptible cell line induced resistance to the drug. The number of CA dinucleotide was equivalent in genomic and tumor DNA obtained from 30 patients with head and neck cancer. In a clinical study in colorectal cancer, subjects with lower number of CA dinucleotide frequently developed skin toxicity, a feature that is related to the antitumor activity of this class of drugs. These results suggest that polymorphic variations in the intron 1 of the egfr gene is associated with response to EGFR inhibitors and may provide an explanation as to why the development of skin toxicity is associated with a favorable outcome in patients treated with these agents.
Cleavage of Lumican by Membrane-Type Matrix Metalloproteinase-1 Abrogates This Proteoglycan-Mediated Suppression of Tumor Cell Colony Formation in Soft Agar
Authors: Li Yingyi , Aoki Takanori , Mori Yuya , Ahmad Munirah , Miyamori Hisashi , Takino Takahisa , Sato Hiroshi 
Published: September 2005

Abstract
The small leucine-rich proteoglycan lumican was identified from a human placenta cDNA library by the expression cloning method as a gene product that interacts with membrane-type matrix metalloproteinase-1 (MT1-MMP). Coexpression of MT1-MMP with lumican in HEK293T cells reduced the concentration of lumican secreted into culture medium, and this reduction was abolished by addition of the MMP inhibitor BB94. Lumican protein from bovine cornea and recombinant lumican core protein fused to glutathione S-transferase was shown to be cleaved at multiple sites by recombinant MT1-MMP. Transient expression of lumican in HEK293 cells induced expression of tumor suppressor gene product p21/Waf-1, which was abrogated by the coexpression of MT1-MMP concomitant with a reduction in lumican concentration in culture medium. Stable expression of lumican in HeLa cells induced expression of p21 and reduction of colony formation in soft agar, which were both abolished by the expression of MT1-MMP. HT1080 fibrosarcoma cells stably transfected with the lumican cDNA (HT1080/Lum), which express endogenous MT1-MMP, secreted moderate levels of lumican; however, treatment of HT1080/Lum cells with BB94 resulted in accumulation of lumican in culture medium. The expression levels of p21 in HT1080/Lum were proportional to the concentration of secreted lumican and showed reverse corelation with colony formation in soft agar. These results suggest that MT1-MMP abrogates lumican-mediated suppression of tumor cell colony formation in soft agar by degrading this proteoglycan, which down-regulates it through the induction of p21.
Cyclooxygenase-1 Deletion Enhances Apoptosis but Does Not Protect Against Ultraviolet Light-Induced Tumors
Authors: Pentland Alice P. , Scott Glynis , VanBuskirk JoAnne , Tanck Carol , LaRossa Gina , Brouxhon Sabine 
Published: September 2005

Abstract
Inhibition or deletion of cyclooxygenase (COX)-2 has been demonstrated to protect against squamous cell cancer in many studies. Although much effort has focused on COX-2 inhibition, recent work indicates that COX-1 deletion may be nearly as protective. In this study, we used SKH-1 hairless mice in which COX-1 was selectively deleted to examine the role of COX-1 in photocarcinogenesis. After UV exposure, 40–60% less prostaglandin E2 was detected in COX-1−/− animals compared with wild-type (WT) controls. A 4-fold induction of keratinocyte apoptosis was observed in knockouts relative to WT animals, as documented by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling and caspase-3 staining. Proliferation was not significantly different in COX-1+/+, COX-1+/−, and COX-1−/− animals. When susceptibility to UV-induced tumor formation was studied, tumor number, average tumor size, and time of tumor onset in COX-1−/− animals were identical to WT controls. Thus, enhanced apoptosis did not alter UV-induced skin carcinogenesis, suggesting other effects are key to nonsteroidal anti-inflammatory drug chemoprevention. These results contrast sharply with data obtained using the classic 7,12-dimethylbenz(a)anthracene/12-O-tetradecanoylphorbol-13-acetate cancer model in which a prominent protective effect of COX-1−/− is present. The lack of protection observed here confirms cancer mechanisms are distinct in UV- and tumor promotor-induced cancer models and indicates that chemoprevention strategies must specifically address cancer causes to be effective.
Overexpression of Hyperactive Integrin-Linked Kinase Leads to Increased Cellular Radiosensitivity
Authors: Cordes Nils 
Published: September 2005

Abstract
Integrin-linked kinase (ILK), bound to the cytoplasmic tails of integrin β1, β2, and β3, is thought to signal through AKT and glycogen synthase kinase-3β (GSK-3β) for survival and proliferation regulation. To determine the role of ILK in the cellular radiation response, stably transfected A549 lung cancer cells overexpressing either wild-type (ILK-wk) or hyperactive ILK (ILK-hk) were studied for survival, signaling, proliferation, and examined in immunofluorescence and adhesion assays. Strong radiosensitization was observed in ILK-hk in contrast to ILK-wk mutants and empty vector controls. ILK small interfering RNA transfections showed radioresistance similar to irradiation on fibronectin. AKT, GSK-3β-cyclin D1, mitogen-activated protein kinase kinase 1/2-mitogen-activated protein kinase, and c-Jun NH2-terminal kinase signaling was dysregulated in irradiated ILK-hk mutants. Immunofluorescence stainings of ILK-hk cells indicated disturbed ILK and paxillin membrane localization with concomitant decrease in focal adhesions. Profound ILK-hk-dependent changes in morphology were characterized by spindle-like cell shape, cell size reduction, increased cell protrusions, strong formation of membranous f-actin rings, and significantly reduced adhesion to matrix proteins. Additionally, ILK-wk and ILK-hk overexpression impaired β1-integrin clustering and protein Tyr-phosphorylation. Taken together, the data provide evidence that ILK signaling modulates the cellular radiation response involving diverse signaling pathways and through changes in f-actin-based processes such as focal adhesion formation, cell adhesion, and spreading. Identification of ILK and its signaling partners as potential targets for tumor radiosensitization might promote innovative anticancer strategies by providing insight into the mechanism of cell adhesion-mediated radioresistance, oncogenic transformation, and tumor growth and spread.
Functional Attributes of Mucosal Immunity in Cervical Intraepithelial Neoplasia and Effects of HIV Infection
Authors: Kobayashi Akiko , Greenblatt Ruth M. , Anastos Kathryn , Minkoff Howard , Massad Leslie S. , Young Mary , Levine Alexandra M. , Darragh Teresa M. , Weinberg Vivian , Smith-McCune Karen K. 
Published: September 2005

Abstract
The role of mucosal immunity in human papillomavirus (HPV)-related cervical diseases is poorly understood. To characterize the local immune microenvironment in cervical intraepithelial neoplasia (CIN) 2/3 and determine the effects of HIV infection, we compared samples from three groups: normal cervix, CIN 2/3 from immunocompetent women (HIV− CIN 2/3), and CIN 2/3 from HIV seropositive women (HIV+ CIN 2/3). CIN 2/3 lesions contained increased numbers of immune cells from both the acquired and innate arms of the immune response in stroma [CD4+ and CD8+ T cells, macrophages, mast cells, B cells, neutrophils, and natural killer (NK) cells] and dysplastic epithelium (CD4+ T cells, macrophages, and NK cells). Immune cells in CIN 2/3 expressed activation markers, as measured by interleukin-2 receptor (IL-2R) and transcription factor T bet. Interferon-γ production was significantly up-regulated in CIN lesions and was expressed by CD4+ and CD8+ T cells and NK cells, indicating the activation of immune cells. Abundant presence of transforming growth factor-β+ CD25+ cells in the infiltrates associated with CIN lesions, and of immature CD1a+ dendritic cells expressing IL-10 and transforming growth factor-β, indicate that CIN is associated with an influx of immune cells that produce a mixture of proinflammatory and regulatory cytokines. In HIV+ CIN, immune cell densities (CD4+ T cells, macrophages, neutrophils, and NK cells) and expression of interferon-γ were significantly decreased compared with HIV− CIN. Regulatory cytokines were also down-regulated in this group. Therefore, both pro- and anti-inflammatory responses present in CIN 2/3 lesions are suppressed in HIV-seropositive women.
The Role of Defective Mismatch Repair in Small Bowel Adenocarcinoma in Celiac Disease
Authors: Potter D. Dean , Murray Joseph A. , Donohue John H. , Burgart Lawrence J. , Nagorney David M. , van Heerden Jon A. , Plevak Matthew F. , Zinsmeister Alan R. , Thibodeau Stephen N. 
Published: September 2005

Abstract
Celiac disease is associated with an increased risk of small bowel adenocarcinoma. The aims of this study were to investigate the molecular basis, assess outcomes, and identify clinicopathologic characteristics of small bowel adenocarcinoma in celiac disease. Retrospective case control cohort study of all celiac disease patients treated at our institution for small bowel adenocarcinoma and matched control patients with sporadic small bowel adenocarcinoma from July 1960 to November 2002. Mismatch repair (MMR) status was accessed by testing tissue for microsatellite instability (MSI) and for hMLH1 and hMSH2 protein expression. Over a 40-year time period, 18 patients with small bowel adenocarcinoma and celiac disease were treated at the Mayo Clinic. One celiac disease patient was excluded. High-frequency MSI (MSI-H) was identified in 8 of 11 (73%) and 2 of 22 (9%) available small bowel adenocarcinoma specimens in the celiac disease and control groups, respectively. In the celiac disease group, MSI-H was associated with loss of hMLH1 and hMSH2 in 6 and 1 specimens, respectively. Loss of hMLH1 occurred in both control tumors. Stage was associated with celiac disease status (P = 0.018), and 78% of controls were stage III or IV compared with 47% of celiac disease patients. Overall, survival was better (P = 0.025) in the celiac disease group compared with stage-matched controls. Celiac disease patients with small bowel adenocarcinoma had a high incidence defective MMR (73%) compared with controls and had better survival compared with stage-matched controls. In addition, celiac disease patients presented more frequently with early-stage small bowel adenocarcinoma. The better survival and earlier presentation of small bowel adenocarcinoma in celiac disease appears to be biologically associated with defective MMR.