bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Mammalian Tumor Xenografts Induce Neovascularization in Zebrafish Embryos
Authors: Nicoli Stefania , Ribatti Domenico , Cotelli Franco , Presta Marco
Published: March 2023

Abstract
The zebrafish (Danio rerio)/tumor xenograft model represents a powerful new model system in cancer. Here, we describe a novel exploitation of the zebrafish model to investigate tumor angiogenesis, a pivotal step in cancer progression and target for antitumor therapies. Human and murine tumor cell lines that express the angiogenic fibroblast growth factor (FGF) 2 and/or vascular endothelial growth factor (VEGF) induce the rapid formation of a new microvasculature when grafted close to the developing subintestinal vessels of zebrafish embryos at 48 h postfertilization. Instead, no angiogenic response was exerted by related cell clones defective in the production of these angiogenic growth factors. The newly formed blood vessels sprout from the subintestinal plexus of the zebrafish embryo, penetrate the tumor graft, and express the transcripts for the zebrafish orthologues of the early endothelial markers Fli-1, VEGF receptor-2 (VEGFR2/KDR), and VE-cadherin. Accordingly, green fluorescent protein–positive neovessels infiltrate the graft when tumor cells are injected in transgenic VEGFR2:G-RCFP zebrafish embryos that express green fluorescent protein under the control of the VEGFR2/KDR promoter. Systemic exposure of zebrafish embryos immediately after tumor cell injection to prototypic antiangiogenic inhibitors, including the FGF receptor tyrosine kinase inhibitor SU5402 and the VEGFR2/KDR tyrosine kinase inhibitor SU5416, suppresses tumor-induced angiogenesis without affecting normal blood vessel development. Accordingly, VE-cadherin gene inactivation by antisense morpholino oligonucleotide injection inhibits tumor neovascularization without affecting the development of intersegmental and subintestinal vessels. These data show that the zebrafish/tumor xenograft model represents a novel tool for investigating the neovascularization process exploitable for drug discovery and gene targeting in tumor angiogenesis. [Cancer Res 2007;67(7):2927–31]
Data from Improvement of Antitumor Activity by Gene Amplification with a Replicating but Nondisseminating Adenovirus
Authors: Bourbeau Denis , Lau Cara Jean , Jaime Jairo , Koty Zafiro , Zehntner Simone P. , Lavoie Geneviève , Mes-Masson Anne-Marie , Nalbantoglu Josephine , Massie Bernard
Published: March 2023

Abstract
Gene therapy is a promising approach for cancer treatment; however, efficacy of current vectors remains insufficient. To improve the success of suicide gene therapy, we constructed a replication-competent adenoviral vector that has its protease gene deleted and expresses bacterial cytosine deaminase fused with bacterial uracil phosphoribosyltransferase (CU). The prodrug, 5-fluorocytosine, is transformed into the highly toxic and tissue-diffusible 5-fluorouracil by CU in infected cells. This vector is incapable of producing infectious particles but is able to undergo a single round of replication, thereby increasing transgene copy number and expression. In the presence of 5-FC, compared with the first-generation vector (AdCU), the replication-competent vector, Ad(dPS)CU-IRES-E1A, was significantly more efficacious for in vitro tumor cell killing and in bystander assays, whereas 25-fold fewer viral particles were required in a three-dimensional spheroid model. For in vivo experiments, in which virus was injected into preestablished intracranial glioma xenografts, followed by 5-FC treatment, mice receiving Ad(dPS)CU-IRES-E1A had significantly smaller tumors at 35 days postinjection as well as significantly longer median survival than mice treated with the replication-deficient, protease-deleted vector [Ad(dPS)CU]. In an immunocompetent syngeneic model, Ad(dPS)CU + 5-FC–treated mice had a median survival of only 23 days, whereas Ad(dPS)CU-IRES-E1A + 5-FC–treated animals had a survival of 57.1% at 365 days. In conclusion, Ad(dPS)CU-IRES-E1A in the presence of 5-FC produces more potent tumoricidal effects than its replication-deficient counterparts. [Cancer Res 2007;67(7):3387–95]
Data from Transforming Growth Factor-β Promotes Survival of Mammary Carcinoma Cells through Induction of Antiapoptotic Transcription Factor DEC1
Authors: Ehata Shogo , Hanyu Aki , Hayashi Makoto , Aburatani Hiroyuki , Kato Yukio , Fujime Makoto , Saitoh Masao , Miyazawa Keiji , Imamura Takeshi , Miyazono Kohei
Published: March 2023

Abstract
Transforming growth factor-β (TGF-β) signaling facilitates tumor growth and metastasis in advanced cancer. In the present study, we identified differentially expressed in chondrocytes 1 (DEC1, also known as SHARP2 and Stra13) as a downstream target of TGF-β signaling, which promotes the survival of breast cancer cells. In the mouse mammary carcinoma cell lines JygMC(A) and 4T1, the TGF-β type I receptor kinase inhibitors A-44-03 and SB431542 induced apoptosis of cells under serum-free conditions. Oligonucleotide microarray and real-time reverse transcription-PCR analyses revealed that TGF-β induced DEC1 in these cells, and the increase of DEC1 was suppressed by the TGF-β type I receptor kinase inhibitors as well as by expression of dominant-negative TGF-β type II receptor. Overexpression of DEC1 prevented the apoptosis of JygMC(A) cells induced by A-44-03, and knockdown of endogenous DEC1 abrogated TGF-β–promoted cell survival. Moreover, a dominant-negative mutant of DEC1 prevented lung and liver metastasis of JygMC(A) cells in vivo. Our observations thus provide new insights into the molecular mechanisms governing TGF-β–mediated cell survival and metastasis of cancer. [Cancer Res 2007;67(20):9694–703]
Data from Inhibitor of Growth 4 Suppresses Cell Spreading and Cell Migration by Interacting with a Novel Binding Partner, Liprin α1
Authors: Shen Jiang-Cheng , Unoki Motoko , Ythier Damien , Duperray Alain , Varticovski Lyuba , Kumamoto Kensuke , Pedeux Remy , Harris Curtis C.
Published: March 2023

Abstract
Inhibitor of growth 4 (ING4) is a candidate tumor suppressor that plays a major role in gene regulation, cell cycle control, apoptosis, and angiogenesis. ING4 expression is down-regulated in glioblastoma cells and head and neck squamous cell carcinoma. Here, we identified liprin α1/PPFIA1, a cytoplasmic protein necessary for focal adhesion formation and axon guidance, as a novel interacting protein with ING4. ING4 and liprin α1 colocalized at lamellipodia in the vicinity of vinculin. Overexpressed ING4 suppressed cell spreading and cell migration. In contrast, overexpressed liprin α1 enhanced cell spreading and cell migration. Knockdown of endogenous ING4 with RNA interference induced cell motility, whereas knockdown of endogenous liprin α1 suppressed cell motility. ING4 also suppressed cell motility that was enhanced by liprin α1. However, ING4 did not further suppress cell motility when liprin α1 was suppressed with RNA interference, suggesting a functional and mechanistic interdependence between these proteins. In addition to its nuclear functions, cytoplasmic ING4 interacts with liprin α1 to regulate cell migration and, with its known antiangiogenic function, may prevent invasion and metastasis. [Cancer Res 2007;67(6):2552–8]
Data from Expression of CDK4 or CDK2 in Mouse Oral Cavity Is Retained in Adult Pituitary with Distinct Effects on Tumorigenesis
Authors: Macias Everardo , Miliani de Marval Paula L. , Senderowicz Adrian , Cullen John , Rodriguez-Puebla Marcelo L.
Published: March 2023

Abstract
The keratin 5 (K5) promoter drives transgenic expression to the basal cell layer of stratified epithelia. Surprisingly, analysis of K5CDK4 and K5CDK2 transgenic mouse embryos showed CDK4 and CDK2 expression not only in the expected tissues, but also in the adenohypophysis. This organ is derived from an upwards growth of the primitive oropharnyx, a K5-expressing tissue. We show that transgenic expression of CDKs in the embryonic oral ectoderm is specifically retained in undifferentiated cells from the pars intermedia of the adenohypophysis. Interestingly, we found that K5CDK4 mice show a decreased number of pituitary stem cells, even though CDK4 is not expressed in the stem cells but in transit-amplifying (TA)–like cells. Interestingly, CDK4-expressing cells, but not CDK2-expressing cells, strongly synergize with lack of p27Kip1 to generate pituitary carcinomas that appear with shortened latency and are drastically more aggressive than those arising in p27−/− mice. Thus, we show that deregulation of CDK expression in the primitive oral epithelium plays a unique function, providing a selective advantage that gives rise to transgene-positive TA-like pituitary cells. Furthermore, retention of CDK4 in these TA-like pituitary cells synergizes with loss of p27Kip1 to induce pituitary adenocarcinomas. This model suggests that forced expression of CDK4 sensitizes cells and synergizes with a second change resulting in tumor development. [Cancer Res 2008;68(1):162–71]
Data from Neuroblastoma Cells Isolated from Bone Marrow Metastases Contain a Naturally Enriched Tumor-Initiating Cell
Authors: Hansford Loen M. , McKee Amy E. , Zhang Libo , George Rani E. , Gerstle J. Ted , Thorner Paul S. , Smith Kristen M. , Look A. Thomas , Yeger Herman , Miller Freda D. , Irwin Meredith S. , Thiele Carol J. , Kaplan David R.
Published: March 2023

Abstract
Neuroblastoma is a heterogeneous pediatric tumor thought to arise from the embryonic neural crest. Identification of the cell responsible for propagating neuroblastomas is essential to understanding this often recurrent, rapidly progressing disease. We have isolated and characterized putative tumor-initiating cells from 16 tumors and bone marrow metastases from patients in all neuroblastoma risk groups. Dissociated cells from tumors or bone marrow grew as spheres in conditions used to culture neural crest stem cells, were capable of self-renewal, and exhibited chromosomal aberrations typical of neuroblastoma. Primary spheres from all tumor risk groups differentiated under neurogenic conditions to form neurons. Tumor spheres from low-risk tumors frequently formed large neuronal networks, whereas those from high-risk tumors rarely did. As few as 10 passaged tumor sphere cells from aggressive neuroblastoma injected orthotopically into severe combined immunodeficient/Beige mice formed large neuroblastoma tumors that metastasized to liver, spleen, contralateral adrenal and kidney, and lung. Furthermore, highly tumorigenic tumor spheres were isolated from the bone marrow of patients in clinical remission, suggesting that this population of cells may predict clinical behavior and serve as a biomarker for minimal residual disease in high-risk patients. Our data indicate that high-risk neuroblastoma contains a cell with cancer stem cell properties that is enriched in tumor-initiating capacity. These cells may serve as a model system to identify the molecular determinants of neuroblastoma and to develop new therapeutic strategies for this tumor. [Cancer Res 2007;67(23):11234–43]
Data from Automated, Quantitative Screening Assay for Antiangiogenic Compounds Using Transgenic Zebrafish
Authors: Tran T. Cameron , Sneed Blossom , Haider Jamil , Blavo Delali , White Audrey , Aiyejorun Temitope , Baranowski Timothy C. , Rubinstein Amy L. , Doan Thanh N. , Dingledine Raymond , Sandberg Eric M.
Published: March 2023

Abstract
Pathologic angiogenesis has emerged as an important therapeutic target in several major diseases. Zebrafish offer the potential for high-throughput drug discovery in a whole vertebrate system. We developed the first quantitative, automated assay for antiangiogenic compound identification using zebrafish embryos. This assay uses transgenic zebrafish with fluorescent blood vessels to facilitate image analysis. We developed methods for automated drugging and imaging of zebrafish in 384-well plates and developed a custom algorithm to quantify the number of angiogenic blood vessels in zebrafish. The assay was used to screen the LOPAC1280 compound library for antiangiogenic compounds. Two known antiangiogenic compounds, SU4312 and AG1478, were identified as hits. Additionally, one compound with no previously known antiangiogenic activity, indirubin-3′-monoxime (IRO), was identified. We showed that each of the hit compounds had dose-dependent antiangiogenic activity in zebrafish. The IC50 of SU4312, AG1478, and IRO in the zebrafish angiogenesis assay was 1.8, 8.5, and 0.31 μmol/L, respectively. IRO had the highest potency of the hit compounds. Moreover, IRO inhibited human umbilical vein endothelial cell tube formation and proliferation (IC50 of 6.5 and 0.36 μmol/L, respectively). It is therefore the first antiangiogenic compound discovered initially in a zebrafish assay that also has demonstrable activity in human endothelial cell-based angiogenesis assays. [Cancer Res 2007;67(23):11386–92]
Data from Anoikis, Initiated by Mcl-1 Degradation and Bim Induction, Is Deregulated during Oncogenesis
Authors: Woods Nicholas T. , Yamaguchi Hirohito , Lee Francis Y. , Bhalla Kapil N. , Wang Hong-Gang
Published: March 2023

Abstract
Anoikis, a Bax-dependent apoptosis triggered by detachment from the extracellular matrix, is often dysfunctional in metastatic cancer cells. Using wild-type and c-Src–transformed NIH3T3 cells as a model, we identified Mcl-1 degradation and Bim up-regulation as a critical determinant of anoikis initiation. Detachment rapidly degraded Mcl-1 via a GSK-3β–dependent proteasomal pathway and transcriptionally up-regulated Bim expression. Mcl-1 degradation in the presence of Bim was sufficient to induce anoikis. By analyzing nonmetastatic Saos-2 and metastatic derivative LM7 cells, we confirmed that dysregulation of Mcl-1 degradation and Bim induction during detachment contributes to decreased anoikis sensitivity of metastatic cells. Furthermore, knockdown of Mcl-1 or pharmacologic inhibition of the phosphoinositide-3-kinase/Akt and mitogen-activated protein kinase pathways that suppress Mcl-1 degradation and Bim expression could markedly sensitize metastatic breast cancer cells to anoikis and prevent metastases in vivo. Therefore, Mcl-1 degradation primes the cell for Bax activation and anoikis, which can be blocked by oncogenic signaling in metastatic cells. [Cancer Res 2007;67(22):10744–52]
Data from Development of Gastric Tumors in ApcMin/+ Mice by the Activation of the β-Catenin/Tcf Signaling Pathway
Authors: Tomita Hiroyuki , Yamada Yasuhiro , Oyama Takeru , Hata Kazuya , Hirose Yoshinobu , Hara Akira , Kunisada Takahiro , Sugiyama Yasuyuki , Adachi Yosuke , Linhart Heinz , Mori Hideki
Published: March 2023

Abstract
Although several lines of evidence suggest the involvement of the Wnt pathway in the development of gastric cancers, the functional significance of the pathway in gastric carcinogenesis is still poorly defined. To examine the role of the Apc/β-catenin signaling pathway in the development of gastric cancers, we investigated the gastric mucosa of the ApcMin/+ mouse, which is a murine model for familial adenomatous polyposis, carrying a germ-line mutation at codon 850 of Apc. We found that aged ApcMin/+ mice spontaneously develop multiple tumors in the stomach, which are accompanied by loss of heterozygosity of Apc. Such tumors consisted of adenomatous glands with strong nuclear accumulation of β-catenin. Even a single adenomatous gland already showed nuclear accumulation of β-catenin, suggesting that Apc/β-catenin pathway is an initiating event in gastric tumorigenesis in ApcMin/+ mice. Myc and cyclin D1 expressions, which are transcriptional targets of β-catenin/Tcf, increased in the adenomatous lesions. Furthermore, β-catenin/Tcf reporter transgenic mice with ApcMin allele showed higher levels of the transcriptional activity of β-catenin/Tcf in the gastric tumors. We also treated ApcMin/+ and wild-type mice with N-methyl-N-nitrosourea (MNU), an alkylating agent that induces adenomas and adenocarcinomas in the stomach. Consequently, MNU-treated ApcMin/+ mice significantly enhanced the tumor development in comparison with ApcMin/+ mice or MNU-treated wild-type mice. Several gastric tumors in MNU-treated ApcMin/+ mice showed invasion into the submucosal layer. These results indicate that the Apc/β-catenin pathway may play an important role in at least subset of gastric carcinomas. In addition, ApcMin/+ mice combined with MNU could be a useful short-term model to investigate multistage carcinogenesis in the stomach. [Cancer Res 2007;67(9):4079–87]
Data from Snail-Induced Down-Regulation of ΔNp63α Acquires Invasive Phenotype of Human Squamous Cell Carcinoma
Authors: Higashikawa Koichiro , Yoneda Shingo , Tobiume Kei , Taki Masayuki , Shigeishi Hideo , Kamata Nobuyuki
Published: March 2023

Abstract
p63 is a member of the p53 family and regulates crucial events in the formation of epithelial structures, but the role of p63 in tumor is unclear. We found that Snail-induced epithelial-to-mesenchymal transition (EMT) is accompanied by down-regulation of p63 in human squamous cell carcinomas (SCC). ΔNp63α is the predominantly expressed p63 isoform in SCC cells. ΔNp63 promoter activity required a CAAT/enhancer binding protein (C/EBP) binding element and was reduced remarkably by Snail. Down-regulation of ΔNp63α and reduction of C/EBPα were observed in EMT phenotype cells, which exhibited invasive activity in vitro. p63 knockdown in cells enhanced invasive activity in the presence of E-cadherin. Conversely, forced expression of ΔNp63α blocked invasive activity of cells with the EMT phenotype. These findings indicate that Snail down-regulates ΔNp63α, leading to acquisition of the invasive phenotype by SCC. The invasive activity caused by down-regulation of ΔNp63α does not require down-regulation of E-cadherin. [Cancer Res 2007;67(19):9207–13]
Data from Phosphatase and Tensin Homologue Deleted on Chromosome 10 Deficiency Accelerates Tumor Induction in a Mouse Model of ErbB-2 Mammary Tumorigenesis
Authors: Dourdin Nathalie , Schade Babette , Lesurf Robert , Hallett Michael , Munn Robert J. , Cardiff Robert D. , Muller William J.
Published: March 2023

Abstract
Loss of the tumor suppressor phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and amplification or elevated expression of ErbB-2 are both involved in human breast cancer. To directly test the importance of these genetic events in mammary tumorigenesis, we have assessed whether mammary-specific disruption of PTEN could cooperate with activation of ErbB-2. Transgenic mice expressing ErbB-2 under the transcriptional control of its endogenous promoter (ErbB-2KI) were interbred with mice carrying conditional PTEN alleles and an MMTV/Cre transgene. Loss of one or both PTEN alleles resulted in a dramatic acceleration of mammary tumor onset and an increased occurrence of lung metastases in the ErbB-2KI strain. Tumor progression in PTEN-deficient/ErbB-2KI strains was associated with elevated ErbB-2 protein levels, which were not due to ErbB-2 amplification or to a dramatic increase in ErbB-2 transcripts. Moreover, the PTEN-deficient/ErbB-2KI–derived mouse mammary tumors display striking morphologic heterogeneity in comparison with the homogeneous pathology of the ErbB-2KI parental strain. Therefore, inactivation of PTEN would not only have a dramatic effect on ErbB-2–induced mammary tumorigenesis but would also lead to the formation of mammary tumors that, in part, display pathologic and molecular features associated with the basal-like subtype of primary human breast cancer. [Cancer Res 2008;68(7):2122–31]
Data from Hypoxia Down-regulates CCAAT/Enhancer Binding Protein-α Expression in Breast Cancer Cells
Authors: Seifeddine Ramzi , Dreiem Anne , Blanc Etienne , Fulchignoni-Lataud Marie-Claude , Belda Marie-Aude Le Frère , Lecuru Fabrice , Mayi Thérèse Hervèe , Mazure Nathalie , Favaudon Vincent , Massaad Charbel , Barouki Robert , Massaad-Massade Liliane
Published: March 2023

Abstract
The transcription factor CCAAT/enhancer binding protein-α (C/EBPα) is involved in the control of cell differentiation and proliferation, and has been suggested to act as a tumor suppressor in several cancers. By using microarray analysis, we have previously shown that hypoxia and estrogen down-regulate C/EBPα mRNA in T-47D breast cancer cells. Here, we have examined the mechanism by which the down-regulation by hypoxia takes place. Using the specific RNA polymerase II inhibitor 5,6-dichlorobenzimidazole-1-β-d-ribofuranoside, the mRNA stability was analyzed under normoxia or hypoxia by quantitative reverse transcription-PCR. Hypoxia reduced the half-life of C/EBPα mRNA by ∼30%. C/EBPα gene promoter studies indicated that hypoxia also repressed the transcription of the gene and identified a hypoxia-responsive element (−522; −527 bp), which binds to hypoxia-inducible factor (HIF)-1α, as essential for down-regulation of C/EBPα transcription in hypoxia. Immunocytochemical analysis showed that C/EBPα was localized in the nucleus at 21% O2, but was mostly cytoplasmic under 1% O2. Knockdown of HIF-1α by RNAi restored C/EBPα to normal levels under hypoxic conditions. Immunohistochemical studies of 10 tumor samples did not show any colocalization of C/EBPα and glucose transporter 1 (used as a marker for hypoxia). Taken together, these results show that hypoxia down-regulates C/EBPα expression in breast cancer cells by several mechanisms, including transcriptional and posttranscriptional effects. The down-regulation of C/EBPα in hypoxia is mediated by HIF-1. [Cancer Res 2008;68(7):2158–65]
Data from Concordant Epigenetic Silencing of Transforming Growth Factor-β Signaling Pathway Genes Occurs Early in Breast Carcinogenesis
Authors: Hinshelwood Rebecca A. , Huschtscha Lily I. , Melki John , Stirzaker Clare , Abdipranoto Andrea , Vissel Bryce , Ravasi Timothy , Wells Christine A. , Hume David A. , Reddel Roger R. , Clark Susan J.
Published: March 2023

Abstract
Human mammary epithelial cells (HMEC) grown under standard cell culture conditions enter a growth phase referred to as selection, but a subpopulation is able to escape from arrest and continue to proliferate. These cells, called post-selection or variant HMECs, may be derived from progenitor cells found in normal mammary epithelium that subsequently acquire premalignant lesions, including p16INK4A promoter hypermethylation. Epigenetic silencing of tumor suppressor genes through DNA methylation and histone modification is an early event in tumorigenesis. A major challenge is to find genes or gene pathways that are commonly silenced to provide early epigenetic diagnostic and therapeutic cancer targets. To identify very early epigenetic events that occur in breast cancer, we used microarrays to screen for gene pathways that were suppressed in post-selection HMECs but reactivated after treatment with the demethylation agent 5-aza-2′-deoxycytidine. We found that several members of the transforming growth factor β (TGF-β) signaling pathway were consistently down-regulated in the post-selection HMEC populations, and this was associated with a marked decrease in Smad4 nuclear staining. Gene suppression was not associated with DNA methylation but with chromatin remodeling, involving a decrease in histone H3 lysine 27 trimethylation and an increase in histone H3 lysine 9 dimethylation and deacetylation. These results show for the first time that TGF-β2, its receptors TGF-βR1 and TGF-βR2, and activator thrombospondin-1 are concordantly suppressed early in breast carcinogenesis by histone modifications and indicate that the TGF-β signaling pathway is a novel target for gene activation by epigenetic therapy. [Cancer Res 2007;67(24):11517–27]
Data from Early-Onset Lymphoma and Extensive Embryonic Apoptosis in Two Domain-Specific Fen1 Mice Mutants
Authors: Larsen Elisabeth , Kleppa Liv , Meza Trine J. , Meza-Zepeda Leonardo A. , Rada Christina , Castellanos Cesilie G. , Lien Guro F. , Nesse Gaute J. , Neuberger Michael S. , Laerdahl Jon K. , William Doughty Richard , Klungland Arne
Published: March 2023

Abstract
Flap endonuclease 1 (FEN1) processes Okazaki fragments in lagging strand DNA synthesis, and FEN1 is involved in several DNA repair pathways. The interaction of FEN1 with the proliferating cell nuclear antigen (PCNA) processivity factor is central to the function of FEN1 in both DNA replication and repair. Here we present two gene-targeted mice with mutations in FEN1. The first mutant mouse carries a single amino acid point mutation in the active site of the nuclease domain of FEN1 (Fen1E160D/E160D), and the second mutant mouse contains two amino acid substitutions in the highly conserved PCNA interaction domain of FEN1 (Fen1ΔPCNA/ΔPCNA). Fen1E160D/E160D mice develop a considerably elevated incidence of B-cell lymphomas beginning at 6 months of age, particularly in females. By 16 months of age, more than 90% of the Fen1E160D/E160D females have tumors, primarily lymphomas. By contrast, Fen1ΔPCNA/ΔPCNA mouse embryos show extensive apoptosis in the forebrain and vertebrae area and die around stage E9.5 to E11.5. [Cancer Res 2008;68(12):4571–8]
Data from 5-Azacytidine–Induced Methyltransferase-DNA Adducts Block DNA Replication In vivo
Authors: Kuo H. Kenny , Griffith Jack D. , Kreuzer Kenneth N.
Published: March 2023

Abstract
5-Azacytidine (aza-C) and its derivatives are cytidine analogues used for leukemia chemotherapy. The primary effect of aza-C is the prohibition of cytosine methylation, which results in covalent methyltransferase-DNA (MTase-DNA) adducts at cytosine methylation sites. These adducts have been suggested to cause chromosomal rearrangements and contribute to cytotoxicity, but the detailed mechanisms have not been elucidated. We used two-dimensional agarose gel electrophoresis and electron microscopy to analyze plasmid pBR322 replication dynamics in Escherichia coli cells grown in the presence of aza-C. Two-dimensional gel analysis revealed the accumulation of specific bubble and Y molecules, dependent on overproduction of the cytosine MTase EcoRII (M.EcoRII) and treatment with aza-C. Furthermore, a point mutation that eliminates a particular EcoRII methylation site resulted in disappearance of the corresponding bubble and Y molecules. These results imply that aza-C–induced MTase-DNA adducts block DNA replication in vivo. RecA-dependent X structures were also observed after aza-C treatment. These molecules may be generated from blocked forks by recombinational repair and/or replication fork regression. In addition, electron microscopy analysis revealed both bubbles and rolling circles (RC) after aza-C treatment. These results suggest that replication can switch from theta to RC mode after a replication fork is stalled by an MTase-DNA adduct. The simplest model for the conversion of theta to RC mode is that the blocked replication fork is cleaved by a branch-specific endonuclease. Such replication-dependent DNA breaks may represent an important pathway that contributes to genome rearrangement and/or cytotoxicity. [Cancer Res 2007;67(17):8248–54]
Data from The Lysine 831 of Vascular Endothelial Growth Factor Receptor 1 Is a Novel Target of Methylation by SMYD3
Authors: Kunizaki Masaki , Hamamoto Ryuji , Silva Fabio Pittella , Yamaguchi Kiyoshi , Nagayasu Takeshi , Shibuya Masabumi , Nakamura Yusuke , Furukawa Yoichi
Published: March 2023

Abstract
We previously identified SMYD3 as a histone methyltransferase and showed that its expression was elevated in colorectal, hepatocellular, and breast carcinomas. In the investigation of methyltransferase activity of SMYD3, we have found that vascular endothelial growth factor receptor 1 (VEGFR1) was also methylated by SMYD3. We further identified the methylated residue at VEGFR1 lysine 831, which is located in the kinase domain and is conserved among VEGFR1 orthologues. We also found that the lysine is followed by serine, which is conserved among some of the methylation targets of histone methyltransferases. Furthermore, methylation of VEGFR1 enhanced its kinase activity in cells. These data should be helpful for the profound understanding of the biological role of SMYD3 and regulatory mechanisms of VEGFR1. Additionally our finding may facilitate the development of strategies that may inhibit the progression of cancer cells. [Cancer Res 2007;67(22):10759–65]
Data from PRL-3 Down-regulates PTEN Expression and Signals through PI3K to Promote Epithelial-Mesenchymal Transition
Authors: Wang Haihe , Quah Samantha Yiling , Dong Jing Ming , Manser Edward , Tang Jing Ping , Zeng Qi
Published: March 2023

Abstract
PRL-3 is a metastasis-associated phosphatase. We and others have shown that its overexpression increases cell motility and invasiveness. These phenotypic changes are reminiscent of the epithelial-mesenchymal transition (EMT) that occurs during embryonic development and oncogenesis. The EMT is a complex process that converts epithelia into migratory mesenchymal cells. We here attempt to unravel the underlying mechanistic basis of these phenomena. HeLa cells transiently expressing EGFP-PRL-3 (HeLa-PRL-3) exhibit reduced levels of paxillin. Similarly, Chinese hamster ovary cells stably expressing myc-PRL-3 (CHO-PRL-3) also show marked reductions in paxillin, phosphorylated paxillin-Tyr31, and vinculin at focal adhesion complexes and notable reductions in the levels of RhoA-GTP, Rac1-GTP, and filamentous-actin filaments. DLD-1 human colorectal cancer cells engineered to express EGFP-PRL-3 (DLD-1-PRL-3) underwent changes consistent with EMT. In these cells, PRL-3 activates Akt and inactivates glycogen synthase kinase-3β as assessed by phosphospecific antibodies. PRL-3 up-regulates mesenchymal markers fibronectin and Snail and down-regulates epithelial markers E-cadherin, γ-catenin (plakoglobin), and integrin β3, which are major effectors in the EMT pathway. The changes in these EMT characteristics brought about by PRL-3 can be abrogated by the phosphoinositide 3-kinase (PI3K) inhibitor LY294002, implying that PRL-3 acts upstream of PI3K and could play an initiating role to trigger the EMT switch during cancer metastasis. In addition, PRL-3 can down-regulate phosphatase and tensin homologue deleted on chromosome 10, which is an important antagonist of PI3K, further reinforcing PI3K/Akt function in PRL-3–triggered EMT. Catalytically inactive PRL-3 (C104S) was impaired in the above PRL-3–mediated events, indicating that these properties require phosphatase activity. Targeting PRL-3 may thus be a useful strategy to impede cancer cell invasion and metastasis. [Cancer Res 2007;67(7):2922–6]
Data from Pyrimethamine Induces Apoptosis of Melanoma Cells via a Caspase and Cathepsin Double-Edged Mechanism
Authors: Giammarioli Anna Maria , Maselli Angela , Casagrande Andrea , Gambardella Lucrezia , Gallina Angelo , Spada Massimo , Giovannetti Antonello , Proietti Enrico , Malorni Walter , Pierdominici Marina
Published: March 2023

Abstract
The unresponsiveness of metastatic melanoma to conventional chemotherapeutic and biological agents is largely due to the development of resistance to apoptosis. Pyrimethamine belongs to the group of antifolate drugs, and in addition to antiprotozoan effects, it exerts a strong proapoptotic activity, which we recently characterized in human T lymphocytes. However, no data regarding pyrimethamine anticancer activity are available thus far. To this end, we examined the in vitro effects of pyrimethamine on apoptosis, cell cycle distribution, and cell proliferation of human metastatic melanoma cell lines. The in vivo antitumor potential of pyrimethamine was evaluated in a severe combined immunodeficiency (SCID) mouse xenotransplantation model. Our data indicate that pyrimethamine, when used at a clinically relevant concentration, induced apoptosis in metastatic melanoma cells via the activation of the cathepsin B and the caspase cascade (i.e., caspase-8 and caspase-9) and subsequent mitochondrial depolarization. This occurred independently from CD95/Fas engagement. Moreover, pyrimethamine induced a marked inhibition of cell growth and an S-phase cell cycle arrest. Results obtained in SCID mice, injected s.c. with metastatic melanoma cells and treated with pyrimethamine, indicated a significant inhibitory effect on tumor growth. In conclusion, our results suggest that pyrimethamine-induced apoptosis may be considered as a multifaceted process, in which different inducers or regulators of apoptosis are simultaneously implicated, thus permitting death defects of melanoma cells to be bypassed or overcome. On these bases, we hypothesize that pyrimethamine could represent an interesting candidate for the treatment of metastatic melanoma. [Cancer Res 2008;68(13):5291–300]
Data from Two Unique Novel Prostate-Specific and Androgen-Regulated Fusion Partners of ETV4 in Prostate Cancer
Authors: Hermans Karin G. , Bressers Anke A. , van der Korput Hetty A. , Dits Natasja F. , Jenster Guido , Trapman Jan
Published: March 2023

Abstract
Recently, fusion of ERG to the androgen-regulated, prostate-specific TMPRSS2 gene has been identified as the most frequent genetic alteration in prostate cancer. At low frequency, TMPRSS2-ETV1 and TMPRSS2-ETV4 fusion genes have been described. In this study, we report two novel ETV4 fusion genes in prostate cancer: KLK2-ETV4 and CANT1-ETV4. Both gene fusions have important unique aspects. KLK2 is a well-established androgen-induced and prostate-specific gene. Fusion of KLK2 to ETV4 results in the generation of an additional ETV4 exon, denoted exon 4a. This novel exon delivers an ATG for the longest open reading frame, in this way avoiding translation start in KLK2 exon 1. Although wild-type CANT1 has two alternative first exons (exons 1 and 1a), only exon 1a was detected in CANT1-ETV4 fusion transcripts. We show that CANT1 transcripts starting at exon 1a have an androgen-induced and prostate-specific expression pattern, whereas CANT1 transcripts starting at exon 1 are not prostate specific. So, the two novel ETV4 fusion partners possess as predominant common characteristics androgen-induction and prostate-specific expression. [Cancer Res 2008;68(9):3094–8]
Data from Modeling Genomic Diversity and Tumor Dependency in Malignant Melanoma
Authors: Lin William M. , Baker Alissa C. , Beroukhim Rameen , Winckler Wendy , Feng Whei , Marmion Jennifer M. , Laine Elisabeth , Greulich Heidi , Tseng Hsiuyi , Gates Casey , Hodi F. Stephen , Dranoff Glenn , Sellers William R. , Thomas Roman K. , Meyerson Matthew , Golub Todd R. , Dummer Reinhard , Herlyn Meenhard , Getz Gad , Garraway Levi A.
Published: March 2023

Abstract
The classification of human tumors based on molecular criteria offers tremendous clinical potential; however, discerning critical and “druggable” effectors on a large scale will also require robust experimental models reflective of tumor genomic diversity. Here, we describe a comprehensive genomic analysis of 101 melanoma short-term cultures and cell lines. Using an analytic approach designed to enrich for putative “driver” events, we show that cultured melanoma cells encompass the spectrum of significant genomic alterations present in primary tumors. When annotated according to these lesions, melanomas cluster into subgroups suggestive of distinct oncogenic mechanisms. Integrating gene expression data suggests novel candidate effector genes linked to recurrent copy gains and losses, including both phosphatase and tensin homologue (PTEN)–dependent and PTEN-independent tumor suppressor mechanisms associated with chromosome 10 deletions. Finally, sample-matched pharmacologic data show that FGFR1 mutations and extracellular signal–regulated kinase (ERK) activation may modulate sensitivity to mitogen-activated protein kinase/ERK kinase inhibitors. Genetically defined cell culture collections therefore offer a rich framework for systematic functional studies in melanoma and other tumors. [Cancer Res 2008;68(3):664–73]
Data from Ultrasound Imaging of Apoptosis in Tumor Response: Novel Preclinical Monitoring of Photodynamic Therapy Effects
Authors: Banihashemi Behzad , Vlad Roxana , Debeljevic Branislav , Giles Anoja , Kolios Michael C. , Czarnota Gregory J.
Published: March 2023

Abstract
High-frequency ultrasound is a novel method to detect apoptotic cell death based on changes in cell morphology that cause alterations in the viscoelastic and, consequently, the acoustic properties of cell ensembles and tissues. In this study, we evaluated the first preclinical tumor-based use of high-frequency ultrasound spectroscopy to noninvasively monitor tumor treatment by following xenograft malignant melanoma tumor responses to photodynamic therapy (PDT) in vivo. We observed a time-dependant increase in ultrasound backscatter variables after treatment. The observed increases in spectroscopic variables correlated with morphologic findings, indicating increases in apoptotic cell death, which peaked at 24 hours after PDT. We analyzed the changes in spectral slope and backscatter in relation to apoptosis and histologic variations in cell nuclear size. Changes in spectral slope strongly correlated with the changes in mean nuclear size over time, associated with apoptosis, after PDT (P < 0.05). At 48 hours, a decrease in ultrasound backscatter was observed, which could be explained by an increase in cell nuclear degradation. In summary, we show that high-frequency ultrasound spectroscopic variables can be used noninvasively to monitor response after treatment in a preclinical tumor cancer model. These findings provide a foundation for future investigations regarding the use of ultrasound to monitor and aid the customization of treatments noninvasively based on responses to specific interventions. [Cancer Res 2008;68(20):8590–6]
Data from p19Arf Inhibits the Invasion of Hepatocellular Carcinoma Cells by Binding to C-terminal Binding Protein
Authors: Chen Ya-Wen , Paliwal Seema , Draheim Kyle , Grossman Steven R. , Lewis Brian C.
Published: March 2023

Abstract
The INK4A/ARF tumor suppressor locus is frequently inactivated in hepatocellular carcinoma (HCC), yet the consequences of this remain unknown. We recently described a HCC mouse model in which loss of the Ink4a/Arf locus accelerates the development of metastasis and enhances tumor cell migration and invasion in cell culture assays. We show here that knockdown of p19Arf in an HCC cell line increases invasion in cell culture assays. Furthermore, reintroduction of p19Arf into HCC cell lines lacking Ink4a/Arf inhibits tumor cell invasion, without affecting cell proliferation, or cell transformation as measured by soft agar colony formation. Inhibition of cell invasion by p19Arf was dependent on its C-terminal binding protein (CtBP) interaction domain but independent of Mdm2 binding and nucleolar localization. Indeed, RNA interference–mediated knockdown of CtBP1 or CtBP2 decreased cell invasion, and ectopic expression of CtBP2 enhanced tumor cell migration and invasion. Thus, our data indicate a novel role for the Arf tumor suppressor protein in regulating phenotypes associated with tumor progression and metastasis in HCC cells. [Cancer Res 2008;68(2):476–82]
Data from Long-term In vitro Expansion Alters the Biology of Adult Mesenchymal Stem Cells
Authors: Izadpanah Reza , Kaushal Deepak , Kriedt Christopher , Tsien Fern , Patel Bindiya , Dufour Jason , Bunnell Bruce A.
Published: March 2023

Abstract
Mesenchymal stem cells (MSC) derived from bone marrow stem cells (BMSC) and adipose tissue stem cells (ASC) of humans and rhesus macaques were evaluated for their cell cycle properties during protracted culture in vitro. Human ASCs (hASC) and rhesus BMSCs (rBMSC) underwent significantly more total population doublings than human BMSCs (hBMSC) and rhesus ASCs (rASC). The cell cycle profile of all MSCs was altered as cultures aged. hMSCs underwent an increase in the frequency of cells in the S phase at P20 and P30. However, rhesus MSCs from both sources developed a distinct polyploid population of cells at P20, which progressed to aneuploidy by P30. Karyotype analysis of MSCs revealed the development of tetraploid or aneuploid karyotypes in the rhesus cells at P20 or P30. Analysis of the transcriptome of the MSCs from early and late passages revealed significant alterations in the patterns of gene expression (8.8% of the genes were differentially expressed in hBMSCs versus hASCs, and 5.5% in rBMSCs versus rASCs). Gene expression changes were much less evident within the same cell type as aging occurred (0.7% in hMSCs and 0.9% in rMSC). Gene ontology analysis showed that functions involved in protein catabolism and regulation of pol II transcription were overrepresented in rASCs, whereas the regulation of IκB/nuclear factor-κB cascade were overrepresented in hBMSCs. Functional analysis of genes that were differentially expressed in rASCs and hBMSCs revealed that pathways involved in cell cycle, cell cycle checkpoints, protein-ubiquitination, and apoptosis were altered. [Cancer Res 2008;68(11):4229–38]
Data from Multiple Alternative Splicing Markers for Ovarian Cancer
Authors: Klinck Roscoe , Bramard Anne , Inkel Lyna , Dufresne-Martin Geneviève , Gervais-Bird Julien , Madden Richard , Paquet Éric R. , Koh ChuShin , Venables Julian P. , Prinos Panagiotis , Jilaveanu-Pelmus Manuela , Wellinger Raymund , Rancourt Claudine , Chabot Benoit , Abou Elela Sherif
Published: March 2023

Abstract
Intense efforts are currently being directed toward profiling gene expression in the hope of developing better cancer markers and identifying potential drug targets. Here, we present a sensitive new approach for the identification of cancer signatures based on direct high-throughput reverse transcription-PCR validation of alternative splicing events. This layered and integrated system for splicing annotation (LISA) fills a gap between high-throughput microarray studies and high-sensitivity individual gene investigations, and was created to monitor the splicing of 600 cancer-associated genes in 25 normal and 21 serous ovarian cancer tissues. Out of >4,700 alternative splicing events screened, the LISA identified 48 events that were significantly associated with serous ovarian tumor tissues. In a further screen directed at 39 ovarian tissues containing cancer pathologies of various origins, our ovarian cancer splicing signature successfully distinguished all normal tissues from cancer. High-volume identification of cancer-associated splice forms by the LISA paves the way for the use of alternative splicing profiling to diagnose subtypes of cancer. [Cancer Res 2008;68(3):657–63]
Data from Promoter Methylation of Genes in and around the Candidate Lung Cancer Susceptibility Locus 6q23-25
Authors: Tessema Mathewos , Willink Randy , Do Kieu , Yu Yang Y. , Yu Wayne , Machida Emi O. , Brock Malcolm , Van Neste Leander , Stidley Christine A. , Baylin Stephen B. , Belinsky Steven A.
Published: March 2023

Abstract
Chromosomal aberrations associated with lung cancer are frequently observed in the long arm of chromosome 6. A candidate susceptibility locus at 6q23-25 for lung cancer was recently identified; however, no tumor suppressor genes inactivated by mutation have been identified in this locus. Genetic, epigenetic, gene expression, and in silico screening approaches were used to select 43 genes located in 6q12-27 for characterization of methylation status. Twelve (28%) genes were methylated in at least one lung cancer cell line, and methylation of 8 genes was specific to lung cancer cell lines. Five of the 8 genes with the highest prevalence for methylation in cell lines (TCF21, SYNE1, AKAP12, IL20RA, and ACAT2) were examined in primary lung adenocarcinoma samples from smokers (n = 100) and never smokers (n = 75). The prevalence for methylation of these genes was 81%, 50%, 39%, 26%, and 14%, respectively, and did not differ by smoking status or age at diagnosis. Transcription of SYNE1, AKAP12, and IL20RA was completely silenced by hypermethylation and could be restored after treatment with 5-aza-2-deoxycytidine. Significant associations were found between methylation of SYNE1 and TCF21, SYNE1 and AKAP12, and AKAP12 and IL20RA, indicating a coordinated inactivation of these genes in tumors. A higher prevalence for methylation of these genes was not associated with early-onset lung cancer cases, most likely precluding their involvement in familial susceptibility to this disease. Together, our results indicate that frequent inactivation of multiple candidate tumor suppressor genes within chromosome 6q likely contributes to development of sporadic lung cancer. [Cancer Res 2008;68(6):1707–14]
Data from Tumor-Associated MICA Is Shed by ADAM Proteases
Authors: Waldhauer Inja , Goehlsdorf Dennis , Gieseke Friederike , Weinschenk Toni , Wittenbrink Mareike , Ludwig Andreas , Stevanovic Stefan , Rammensee Hans-Georg , Steinle Alexander
Published: March 2023

Abstract
The immunoreceptor NKG2D promotes immunosurveillance of malignant cells and protects the host from tumor initiation by activating natural killer cells and costimulating CD8 T cells. NKG2D-mediated recognition of malignant cells by cytotoxic lymphocytes is enabled through the tumor-associated expression of NKG2D ligands (NKG2DL) resulting from cellular or genotoxic stress. Shedding of NKG2DL is thought to constitute a major countermechanism of tumor cells to subvert NKG2D-mediated immunosurveillance. Here, we report that the prototypical NKG2DL MICA is released by proteolytic cleavage in the stalk of the MICA ectodomain, where deletions, but not alanine substitutions, impede MICA shedding. Small compound-mediated stimulation and inhibition of MICA shedding adduced characteristics that indicated an involvement of members of the “a disintegrin and metalloproteinase” (ADAM) family. Accordingly, MICA shedding by tumor cells was inhibited by silencing of the related ADAM10 and ADAM17 proteases, which are known to promote tumor growth by releasing epidermal growth factor receptor ligands. Collectively, our data show that ADAM10 and ADAM17 are critically involved in the tumor-associated proteolytic release of soluble MICA facilitating tumor immune escape. Hence, therapeutic blockade of ADAM10 and ADAM17 seems promising for cancer treatment by targeting both growth and immune escape of tumors. [Cancer Res 2008;68(15):6368–76]
Data from Activated Ca2+/Calmodulin-Dependent Protein Kinase IIγ Is a Critical Regulator of Myeloid Leukemia Cell Proliferation
Authors: Si Jutong , Collins Steven J.
Published: March 2023

Abstract
Ca2+ signaling is an important component of signal transduction pathways regulating B and T lymphocyte proliferation, but the functional role of Ca2+ signaling in regulating myeloid leukemia cell proliferation has been largely unexplored. We observe that the activated (autophosphorylated) Ca2+/calmodulin-dependent protein kinase IIγ (CaMKIIγ) is invariably present in myeloid leukemia cell lines as well as in the majority of primary acute myelogenous leukemia patient samples. In contrast, myeloid leukemia cells induced to terminally differentiate or undergo growth arrest display a marked reduction in this CaMKIIγ autophosphorylation. In cells harboring the bcr-abl oncogene, the activation (autophosphorylation) of CaMKIIγ is regulated by this oncogene. Moreover, inhibition of CaMKIIγ activity with pharmacologic agents, dominant-negative constructs, or short hairpin RNAs inhibits the proliferation of myeloid leukemia cells, and this is associated with the inactivation/down-regulation of multiple critical signal transduction networks involving the mitogen-activated protein kinase, Janus-activated kinase/signal transducers and activators of transcription (Jak/Stat), and glycogen synthase kinase (GSK3β)/β-catenin pathways. In myeloid leukemia cells, CaMKIIγ directly phosphorylates Stat3 and enhances its transcriptional activity. Thus, CaMKIIγ is a critical regulator of multiple signaling networks regulating the proliferation of myeloid leukemia cells. Inhibiting CaMKIIγ may represent a novel approach in the targeted therapy of myeloid leukemia. [Cancer Res 2008;68(10):3733–42]