bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activation of the Enhancer of Zeste Homologue 2 Gene by the Human Papillomavirus E7 Oncoprotein
Authors: Holland Daniela , Hoppe-Seyler Karin , Schuller Bettina , Lohrey Claudia , Maroldt Julia , Dürst Matthias , Hoppe-Seyler Felix 
Published: December 2008

Abstract
The malignant phenotype of human papillomavirus (HPV)-positive cancer cells is maintained by the activity of the viral E6 and E7 genes. Here, we identified the polycomb group gene enhancer of zeste homologue 2 (EZH2) as a novel downstream target for the viral oncogenes in HPV-transformed cells. EZH2 expression was activated by HPV16 E7 at the transcriptional level via E7-mediated release of E2F from pocket proteins. RNA interference analyses showed that continuous EZH2 expression is required for the proliferation of HPV-positive tumor cells by stimulating cell cycle progression at the G1-S boundary. In addition to its growth-promoting activity, EZH2 also contributed to the apoptotic resistance of cervical cancer cells. Furthermore, we found that HPV-positive dysplastic and tumorigenic cervical lesions were characterized by high levels of EZH2 protein in vivo. We conclude that the E7 target gene EZH2 is a major determinant for the proliferation of HPV-positive cancer cells and contributes to their apoptotic resistance. Moreover, EZH2 may serve as a novel therapeutic target for the treatment of cervical cancer. [Cancer Res 2008;68(23):9964–72]
Molecular Basis for the Critical Role of Suppressor of Cytokine Signaling-1 in Melanoma Brain Metastasis
Authors: Huang Feng-Ju , Steeg Patricia S. , Price Janet E. , Chiu Wen-Tai , Chou Ping-Chieh , Xie Keping , Sawaya Raymond , Huang Suyun 
Published: December 2008

Abstract
Our recent study found that activation of signal transducer and activator of transcription 3 (Stat3) is up-regulated in human brain metastatic cells and contributes to brain metastasis of melanoma. However, the molecular mechanisms underlying this increased Stat3 activation and effect on brain metastasis are unknown. In this report, we showed that the expression of Janus-activated kinase 2 (JAK2), a Stat3 activator, was increased, whereas the expression of a negative regulator of Stat3, suppressor of cytokine signaling-1 (SOCS-1), was reduced in the brain metastatic melanoma cell line A375Br, relative to that in the parental A375P cell line. Consistently, SOCS-1 expression was also lower in the human brain metastatic tissues than in the primary melanoma tissues. Mechanistically, increased JAK2 expression in the A375Br cells was due to, at least in part, its decreased degradation, which was directly correlated with low expression of SOCS-1. Moreover, restoration of SOCS-1 expression resulted in the inhibition of Stat3 activation, whereas depletion of SOCS-1 up-regulated Stat3 activation. These clinical, experimental, and mechanistic findings strongly suggest that increased activation of Stat3 in brain metastatic melanoma cells might be due to decreased SOCS-1 expression. Furthermore, restoration of SOCS-1 expression in brain metastatic A375Br cells significantly inhibited brain metastasis in animal models (P &lt; 0.001). Additionally, alterations of SOCS-1 expression profoundly affected the expression of matrix metalloproteinase-2 (MMP-2), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) and the melanoma cell invasion and angiogenesis. Collectively, these data suggest that the loss of SOCS-1 expression is a critical event, leading to elevated Stat3 signaling and overexpression of MMP-2, bFGF, and VEGF, as well as enhanced invasion and angiogenesis of melanoma cells, consequently promoting brain metastasis. [Cancer Res 2008;68(23):9634–42]
Enterococcus faecalis Induces Aneuploidy and Tetraploidy in Colonic Epithelial Cells through a Bystander Effect
Authors: Wang Xingmin , Allen Toby D. , May Randal J. , Lightfoot Stanley , Houchen Courtney W. , Huycke Mark M. 
Published: December 2008

Abstract
Intestinal commensals are potential important contributors to the etiology of sporadic colorectal cancer, but mechanisms by which bacteria can initiate tumors remain uncertain. Herein, we describe mechanisms that link Enterococcus faecalis, a bacterium known to produce extracellular superoxide, to the acute induction of chromosomal instability. Immortalized human and nontransformed murine colonic epithelial cells, along with a mouse colonic ligation model, were used to assess the effect of E. faecalis on genomic DNA stability and damage. We found that this human intestinal commensal generated aneuploidy, tetraploidy, and γH2AX foci in HCT116, RKO, and YAMC cells. In addition, direct exposure of E. faecalis to these cells induced a G2 cell cycle arrest. Similar observations were noted by exposing cells to E. faecalis–infected macrophages in a dual-chamber coculture system for detecting bystander effects. Manganese superoxide dismutase, catalase, and tocopherols attenuated, and caffeine and inhibitors of glutathione synthase exacerbated, the aneugenic effects and linked the redox-active phenotype of this intestinal commensal to potentially transforming events. These findings provide novel insights into mechanisms by which E. faecalis and intestinal commensals can contribute to cellular transformation and tumorigenesis. [Cancer Res 2008;68(23):9909–17]
Preventive Vaccination with Telomerase Controls Tumor Growth in Genetically Engineered and Carcinogen-Induced Mouse Models of Cancer
Authors: Mennuni Carmela , Ugel Stefano , Mori Federica , Cipriani Barbara , Iezzi Manuela , Pannellini Tania , Lazzaro Domenico , Ciliberto Gennaro , La Monica Nicola , Zanovello Paola , Bronte Vincenzo , Scarselli Elisa 
Published: December 2008

AbstractThe telomerase reverse transcriptase, TERT, is an attractive target for human cancer vaccination because its expression is reactivated in a conspicuous fraction of human tumors. Genetic vaccination with murine telomerase (mTERT) could break immune tolerance in different mouse strains and resulted in the induction of both CD4+ and CD8+ telomerase-specific T cells. The mTERT-derived immunodominant epitopes recognized by CD8+ T cells were further defined in these mouse strains and used to track immune responses. Antitumor efficacy of telomerase-based vaccination was investigated in two cancer models closely resembling human diseases: the TRAMP transgenic mice for prostate cancer and a carcinogen-induced model for colon cancer. TERT overexpression in tumor lesions was shown in both models by immunohistochemistry, thus reinforcing the similarity of these tumors to their human counterparts. Repeated immunizations with mTERT-encoding DNA resulted in a significant delay of tumor formation and progression in both the prostate cancer and the colon cancer models. Moreover, evaluation of the intratumoral infiltrate revealed the presence of telomerase-specific T cells in vaccinated mice. The safety of vaccination was confirmed by the absence of histomorphologic changes on postnecropsy analysis of several organs and lack of adverse effects on blood cell counts. These results indicate that TERT vaccination can elicit antigen-specific immunosurveillance and imply this antigen as a potential candidate for preventive cancer vaccines. [Cancer Res 2008;68(23):9865–74]
Crosstalk between the Androgen Receptor and β-Catenin in Castrate-Resistant Prostate Cancer
Authors: Wang Gang , Wang Jun , Sadar Marianne D. 
Published: December 2008

Abstract
The androgen-signaling pathway plays an important role in the development and hormonal progression of prostate cancer to the castrate-resistant stage (also called androgen-independent or hormone refractory). The Wnt pathway and β-catenin contribute to prostate biology and pathology. Here application of Affymetrix GeneChip analysis revealed the genomic similarity of the LNCaP hollow fiber model to clinical samples and identified genes with differential expression during hormonal progression. The fiber model samples clustered according to the expression profile of androgen-regulated genes to provide genomic evidence for the reactivation of the AR signaling pathway in castrate-resistant prostate cancer. Pathway-based characterization of gene expression identified activation of the Wnt pathway. Together with the increased expression of AR and β-catenin, there was increased nuclear colocalization and interaction of endogenous AR and β-catenin in castrate-resistant prostate cancer from castrated mice. Surprisingly, no interaction or colocalization of AR and β-catenin could be detected in xenografts from noncastrated mice. These studies provide the first in vivo evidence to support aberrant activation of the AR through the Wnt/β-catenin signaling pathway during progression of prostate cancer to the terminal castrate-resistant stage. [Cancer Res 2008;68(23):9918–27]
TSU68 Prevents Liver Metastasis of Colon Cancer Xenografts by Modulating the Premetastatic Niche
Authors: Yamamoto Masayoshi , Kikuchi Hirotoshi , Ohta Manabu , Kawabata Toshiki , Hiramatsu Yoshihiro , Kondo Kenji , Baba Megumi , Kamiya Kinji , Tanaka Tatsuo , Kitagawa Masatoshi , Konno Hiroyuki 
Published: December 2008

AbstractThe aim of this study was to investigate the inhibitory effect of TSU68 [(Z)-5-[(1,2-dihydro-2-oxo-3H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrole-3-propanoic acid; SU6668], an inhibitor of vascular endothelial growth factor receptor 2, platelet-derived growth factor receptor β, and fibroblast growth factor receptor 1 (FGFR1), on colon cancer liver metastasis, and to test the hypothesis that TSU68 modulates the microenvironment in the liver before the formation of metastasis. First, we implanted the highly metastatic human colon cancer TK-4 orthotopically into the cecal walls of nude mice, followed by twice-daily administration of TSU68 (400 mg/kg/d) or vehicle. Five weeks of treatment with TSU68 significantly inhibited liver metastasis compared with the control group (P &lt; 0.001). Next, we analyzed the gene expression profile in premetastatic liver using microarrays. Microarray and quantitative reverse transcription-PCR analysis showed that mRNA levels for the chemokine CXCL1 were significantly increased in tumor-bearing mice compared with non–tumor-bearing mice. Moreover, CXCL1 expression was significantly decreased by TSU68 treatment. CXCR2 expression was detected predominantly on tumor cells in orthotopic tumors compared with ectopic tumors. The number of migrating neutrophils in premetastatic liver was significantly decreased in the TSU68-treated group (P &lt; 0.001). The amount of interleukin-12 (IL-12) p40 in the portal vein was significantly decreased by TSU68 (P = 0.02). Blockade of both CXCR2 and IL-12 p40 with a neutralizing antibody significantly inhibited liver metastasis. These results suggest that the CXCL1/CXCR2 axis is important in cancer metastasis and that TSU68 may modulate the premetastatic niche in the target organ through suppression of the inflammatory response, which might be an alternative mechanism used by antiangiogenic agents. [Cancer Res 2008;68(23):9754–62]
Cranial Irradiation Alters the Behaviorally Induced Immediate-Early Gene Arc (Activity-Regulated Cytoskeleton-Associated Protein)
Authors: Rosi Susanna , Andres-Mach Marta , Fishman Kelly M. , Levy William , Ferguson Ryan A. , Fike John R. 
Published: December 2008

Abstract
Therapeutic irradiation of the brain is commonly used to treat brain tumors but can induce cognitive impairments that can severely affect quality of life. The underlying mechanisms responsible for radiation-induced cognitive deficits are unknown but likely involve alterations in neuronal activity. To gain some mechanistic insight into how irradiation may affect hippocampal neurons known to be associated with cognitive function, we quantitatively assessed the molecular distribution of the behaviorally induced immediate-early gene Arc (activity-regulated cytoskeleton-associated protein) at the level of mRNA and the protein. Young adult C57BL/6J mice received whole-brain irradiation with 0 or 10 Gy, and 1 week or 2 months later, exploration of a novel environment was used to induce Arc expression. The fractions of neurons expressing Arc mRNA and Arc protein were detected using fluorescence in situ hybridization and immunocytochemistry, respectively. Our results showed that there was a significant reduction in the percentage of neurons expressing Arc protein 1 week after irradiation, whereas 2 months after irradiation, there was a reduction in the percentage of neurons expressing both Arc mRNA and Arc protein. Importantly, radiation-induced changes in Arc expression were not a result of neuronal cell loss. The changes observed at 2 months were associated with a significant increase in the number of activated microglia, supporting the idea that inflammation may contribute to neuronal dysfunction. These findings are the first to show that local brain irradiation initiates changes in hippocampal neurons that disrupt the activity patterns (Arc expression) associated with neuroplasticity and memory. [Cancer Res 2008;68(23):9763–70]
Levels of SCS7/FA2H-Mediated Fatty Acid 2-Hydroxylation Determine the Sensitivity of Cells to Antitumor PM02734
Authors: Herrero Ana B. , Astudillo Alma M. , Balboa María A. , Cuevas Carmen , Balsinde Jesús , Moreno Sergio 
Published: December 2008

Abstract
PM02734 is a novel synthetic antitumor drug that is currently in phase I clinical trials. To gain some insight into its mode of action, we used the yeast Saccharomyces cerevisiae as a model system. Treatment of S. cerevisiae with PM02734 rapidly induced necrosis-like cell death, as also found for mammalian cells treated with its close analogue kahalalide F. We have screened the complete set of 4,848 viable S. cerevisiae haploid deletion mutants to identify genes involved in sensitivity or resistance to PM02734. Forty-five percent of the 40 most sensitive strains identified had a role in intracellular vesicle trafficking, indicating that the drug severely affects this process. A mutant strain lacking the sphingolipid fatty acyl 2-hydroxylase Scs7 was found to be the most resistant to PM02734, whereas overexpression of Scs7 rendered the cells hypersensitive to PM02734. To validate these findings in human cells, we did small interfering RNA experiments and also overexpressed the Scs7 human homologue FA2H in human cancer cell lines. As in yeast, FA2H silencing turned the cells resistant to the drug, whereas FA2H overexpression led to an increased sensitivity. Moreover, exogenous addition of the 2-hydroxylated fatty acid 2-hydroxy palmitic acid to different human cell lines increased their sensitivity to the cytotoxic compound. Taken together, these results suggest that the cell membrane and, in particular, 2-hydroxy fatty acid–containing ceramides are important for PM02734 activity. These findings may have important implications in the development of PM02734 because tumor cells with high FA2H expression are expected to be particularly sensitive to this drug. [Cancer Res 2008;68(23):9779–87]
An Epigenetic Genome-Wide Screen Identifies SPINT2 as a Novel Tumor Suppressor Gene in Pediatric Medulloblastoma
Authors: Kongkham Paul N. , Northcott Paul A. , Ra Young Shin , Nakahara Yukiko , Mainprize Todd G. , Croul Sidney E. , Smith Christian A. , Taylor Michael D. , Rutka James T. 
Published: December 2008

Abstract
Medulloblastoma (MB) is a malignant cerebellar tumor that occurs primarily in children. The hepatocyte growth factor (HGF)/MET pathway has an established role in both normal cerebellar development as well as the development and progression of human brain tumors, including MB. To identify novel tumor suppressor genes involved in MB pathogenesis, we performed an epigenome-wide screen in MB cell lines, using 5-aza-2′deoxycytidine to identify genes aberrantly silenced by promoter hypermethylation. Using this technique, we identified an inhibitor of HGF/MET signaling, serine protease inhibitor kunitz-type 2 (SPINT2/HAI-2), as a putative tumor suppressor silenced by promoter methylation in MB. In addition, based on single nucleotide polymorphism array analysis in primary MB samples, we identified hemizygous deletions targeting the SPINT2 locus in addition to gains on chromosome 7 encompassing the HGF and MET loci. SPINT2 gene expression was down-regulated and MET expression was up-regulated in 73.2% and 45.5% of tumors, respectively, by quantitative real-time PCR. SPINT2 promoter methylation was detected in 34.3% of primary MBs examined by methylation-specific PCR. SPINT2 reexpression in MB cell lines reduced proliferative capacity, anchorage independent growth, cell motility in vitro, and increased overall survival times in vivo in a xenograft model (P &lt; 0.0001). Taken together, these data support the role of SPINT2 as a putative tumor suppressor gene in MB, and further implicate dysregulation of the HGF/MET signaling pathway in the pathogenesis of MB. [Cancer Res 2008;68(23):9945–53]
Ionizing Radiation Induces Prostate Cancer Neuroendocrine Differentiation through Interplay of CREB and ATF2: Implications for Disease Progression
Authors: Deng Xuehong , Liu Han , Huang Jiaoti , Cheng Liang , Keller Evan T. , Parsons Sarah J. , Hu Chang-Deng 
Published: December 2008

Abstract
Radiation therapy is a first-line treatment for prostate cancer patients with localized tumors. Although some patients respond well to the treatment, ∼10% of low-risk and up to 60% of high-risk prostate cancer patients experience recurrent tumors. However, the molecular mechanisms underlying tumor recurrence remain largely unknown. Here we show that fractionated ionizing radiation (IR) induces differentiation of LNCaP prostate cancer cells into neuroendocrine (NE)-like cells, which are known to be implicated in prostate cancer progression, androgen-independent growth, and poor prognosis. Further analyses revealed that two cyclic AMP–responsive element binding transcription factors, cyclic AMP–response element binding protein (CREB) and activating transcription factor 2 (ATF2), function as a transcriptional activator and a repressor, respectively, of NE-like differentiation and that IR induces NE-like differentiation by increasing the nuclear content of phospho-CREB and cytoplasmic accumulation of ATF2. Consistent with this notion, stable expression of a nonphosphorylatable CREB or a constitutively nuclear-localized ATF2 in LNCaP cells inhibits IR-induced NE-like differentiation. IR-induced NE-like morphologies are reversible, and three IR-resistant clones isolated from dedifferentiated cells have acquired the ability to proliferate and lost the NE-like cell properties. In addition, these three IR-resistant clones exhibit differential responses to IR- and androgen depletion–induced NE-like differentiation. However, they are all resistant to cell death induced by IR and the chemotherapeutic agent docetaxel and to androgen depletion–induced growth inhibition. These results suggest that radiation therapy–induced NE-like differentiation may represent a novel pathway by which prostate cancer cells survive the treatment and contribute to tumor recurrence. [Cancer Res 2008;68(23):9663–70]
Improved Tumor Immunity Using Anti-Tyrosinase Related Protein-1 Monoclonal Antibody Combined with DNA Vaccines in Murine Melanoma
Authors: Saenger Yvonne M. , Li Yanyun , Chiou Karoline C. , Chan Brian , Rizzuto Gabrielle , Terzulli Stephanie L. , Merghoub Taha , Houghton Alan N. , Wolchok Jedd D. 
Published: December 2008

Abstract
Passive immunization with monoclonal antibody TA99 targeting melanoma differentiation antigen tyrosinase-related protein-1 (Tyrp1; gp75) and active immunization with plasmid DNA encoding altered Tyrp1 both mediate tumor immunity in the B16 murine melanoma model. We report here that TA99 enhances Tyrp1 DNA vaccination in the treatment of B16 lung metastases, an effect mediated by immunologic mechanisms as Tyrp1 has no known role in regulating tumor growth. TA99 is shown to increase induction of anti-Tyrp1 CD8+T-cell responses to DNA vaccination against Tyrp1 as assessed by IFN-γ ELISPOT assays. Immunohistochemistry studies reveal that TA99 localizes rapidly and specifically to B16 lung nodules. Augmentation of T-cell responses is dependent on the presence of tumor as well as on activating Fc receptors. Furthermore, TA99 enhances DNA vaccination against a distinct melanoma antigen, gp100(pmel17/silver locus), improving antitumor efficacy, augmenting systemic CD8+ T-cell responses to gp100, and increasing CD8+ T-cell infiltration at the tumor site. Epitope spreading was observed, with CD8+ T-cell responses generated to Tyrp1 peptide in mice receiving gp100 DNA vaccination in the presence of TA99. Finally, we show that TA99 improves therapeutic efficacy of DNA vaccination combined with adoptive T-cell transfer in treatment of established subcutaneous B16 melanoma. In conclusion, TA99 enhances DNA vaccination against both the target antigen Tyrp1 and a distinct melanoma antigen gp100 in an Fc receptor–dependent mechanism, consistent with enhanced cross-presentation of tumor-derived antigen. Monoclonal antibodies should be tested as vaccine adjuvants in the treatment of cancer. [Cancer Res 2008;68(23):9884–91]
Coevolution of Prostate Cancer and Bone Stroma in Three-Dimensional Coculture: Implications for Cancer Growth and Metastasis
Authors: Sung Shian-Ying , Hsieh Chia-Ling , Law Andrew , Zhau Haiyen E. , Pathak Sen , Multani Asha S. , Lim Sharon , Coleman Ilsa M. , Wu Li-Chin , Figg William D. , Dahut William L. , Nelson Peter , Lee Jae K. , Amin Mahul B. , Lyles Robert , Johnstone Peter A.J. , Marshall Fray F. , Chung Leland W.K. 
Published: December 2008

Abstract
Human bone stromal cells, after three-dimensional coculture with human prostate cancer (PCa) cells in vitro, underwent permanent cytogenetic and gene expression changes with reactive oxygen species serving as mediators. The evolved stromal cells are highly inductive of human PCa growth in mice, and expressed increased levels of extracellular matrix (versican and tenascin) and chemokine (BDFN, CCL5, CXCL5, and CXCL16) genes. These genes were validated in clinical tissue and/or serum specimens and could be the predictors for invasive and bone metastatic PCa. These results, combined with our previous observations, support the concept of permanent genetic and behavioral changes of PCa epithelial cells after being either cocultured with prostate or bone stromal cells as three-dimensional prostate organoids or grown as tumor xenografts in mice. These observations collectively suggest coevolution of cancer and stromal cells occurred under three-dimensional growth condition, which ultimately accelerates cancer growth and metastasis. [Cancer Res 2008;68(23):9996–10003]