bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radionuclide Therapy of HER2-Positive Microxenografts Using a 177Lu-Labeled HER2-Specific Affibody Molecule
Authors: Tolmachev Vladimir , Orlova Anna , Pehrson Rikard , Galli Joakim , Baastrup Barbro , Andersson Karl , Sandström Mattias , Rosik Daniel , Carlsson Jörgen , Lundqvist Hans , Wennborg Anders , Nilsson Fredrik Y. 
Published: March 2007

Abstract
A radiolabeled anti-HER2 Affibody molecule (ZHER2:342) targets HER2-expressing xenografts with high selectivity and gives good imaging contrast. However, the small size (∼7 kDa) results in rapid glomerular filtration and high renal accumulation of radiometals, thus excluding targeted therapy. Here, we report that reversible binding to albumin efficiently reduces the renal excretion and uptake, enabling radiometal-based nuclide therapy. The dimeric Affibody molecule (ZHER2:342)2 was fused with an albumin-binding domain (ABD) conjugated with the isothiocyanate derivative of CHX-A″-DTPA and labeled with the low-energy β-emitter 177Lu. The obtained conjugate [CHX-A″-DTPA-ABD-(ZHER2:342)2] had a dissociation constant of 18 pmol/L to HER2 and 8.2 and 31 nmol/L for human and murine albumin, respectively. The radiolabeled conjugate displayed specific binding to HER2-expressing cells and good cellular retention in vitro. In vivo, fusion with ABD enabled a 25-fold reduction of renal uptake in comparison with the nonfused dimer molecule (ZHER2:342)2. Furthermore, the biodistribution showed high and specific uptake of the conjugate in HER2-expressing tumors. Treatment of SKOV-3 microxenografts (high HER2 expression) with 17 or 22 MBq 177Lu-CHX-A″-DTPA-ABD-(ZHER2:342)2 completely prevented formation of tumors, in contrast to mice given PBS or 22 MBq of a radiolabeled non–HER2-binding Affibody molecule. In LS174T xenografts (low HER2 expression), this treatment resulted in a small but significant increase of the survival time. Thus, fusion with ABD improved the in vivo biodistribution, and the results highlight 177Lu-CHX-A″-DTPA-ABD-(ZHER2:342)2 as a candidate for treatment of disseminated tumors with a high level of HER2 expression. [Cancer Res 2007;67(6):2773–82]
MYCN-Directed Centrosome Amplification Requires MDM2-Mediated Suppression of p53 Activity in Neuroblastoma Cells
Authors: Slack Andrew D. , Chen Zaowen , Ludwig Andrew D. , Hicks John , Shohet Jason M. 
Published: March 2007

Abstract
The MYC family oncogenes cause transformation and tumor progression by corrupting multiple cellular pathways, altering cell cycle progression, apoptosis, and genomic instability. Several recent studies show that MYCC (c-Myc) expression alters DNA repair mechanisms, cell cycle checkpoints, and karyotypic stability, and this is likely partially due to alterations in centrosome replication control. In neuroblastoma cell lines, MYCN (N-Myc) expression induces centrosome amplification in response to ionizing radiation. Centrosomes are cytoplasmic domains that critically regulate cytokinesis, and aberrations in their number or structure are linked to mitotic defects and karyotypic instability. Whereas centrosome replication is linked to p53 and Rb/E2F-mediated cell cycle progression, the mechanisms downstream of MYCN that generate centrosome amplification are incompletely characterized. We hypothesized that MDM2, a direct transcriptional target of MYCN with central inhibitory effects on p53, plays a role in MYC-mediated genomic instability by altering p53 responses to DNA damage, facilitating centrosome amplification. Herein we show that MYCN mediates centrosome amplification in a p53-dependent manner. Accordingly, inhibition of the p53-MDM2 interaction with Nutlin 3A (which activates p53) completely ablates the MYCN-dependent contribution to centrosome amplification after ionizing radiation. We further show that modulating MDM2 expression levels by overexpression or RNA interference–mediated posttranscriptional inhibition dramatically affects centrosome amplification in MYCN-induced cells, indicating that MDM2 is a necessary and sufficient mediator of MYCN-mediated centrosome amplification. Finally, we show a significant correlation between centrosome amplification and MYCN amplification in primary neuroblastoma tumors. These data support the hypothesis that elevated MDM2 levels contribute to MYCN-induced genomic instability through altered regulation of centrosome replication in neuroblastoma. [Cancer Res 2007;67(6):2448–55]
Molecular Cloning of hMena (ENAH) and Its Splice Variant hMena+11a: Epidermal Growth Factor Increases Their Expression and Stimulates hMena+11a Phosphorylation in Breast Cancer Cell Lines
Authors: Di Modugno Francesca , DeMonte Lucia , Balsamo Michele , Bronzi Giovanna , Nicotra Maria Rita , Alessio Massimo , Jager Elke , Condeelis John S. , Santoni Angela , Natali Pier Giorgio , Nisticò Paola 
Published: March 2007

Abstract
hMena (ENAH), an actin regulatory protein involved in the control of cell motility and adhesion, is modulated during human breast carcinogenesis. In fact, whereas undetectable in normal mammary epithelium, hMena becomes overexpressed in high-risk benign lesions and primary and metastatic tumors. In vivo, hMena overexpression correlates with the HER-2+/ER−/Ki67+ unfavorable prognostic phenotype. In vitro, neuregulin-1 up-regulates whereas Herceptin treatment down-modulates hMena expression, suggesting that it may couple tyrosine kinase receptor signaling to the actin cytoskeleton. Herein, we report the cloning of hMena and of a splice variant, hMena+11a, which contains an additional exon corresponding to 21 amino acids located in the EVH2 domain, from a breast carcinoma cell line of epithelial phenotype. Whereas hMena overexpression consistently characterizes the transformed phenotype of tumor cells of different lineages, hMena+11a isoform is concomitantly present only in epithelial tumor cell lines. In breast cancer cell lines, epidermal growth factor (EGF) treatment promotes concomitant up-regulation of hMena and hMena+11a, resulting in an increase of the fraction of phosphorylated hMena+11a isoform only. hMena+11a overexpression and phosphorylation leads to increased p42/44 mitogen-activated protein kinase (MAPK) activation and cell proliferation as evidenced in hMena+11a–transfected breast cancer cell lines. On the contrary, hMena knockdown induces reduction of p42/44 MAPK phosphorylation and of the proliferative response to EGF. The present data provide new insight into the relevance of actin cytoskeleton regulatory proteins and, in particular, of hMena isoforms in coupling multiple signaling pathways involved in breast cancer. [Cancer Res 2007;67(6):2657–65]
Epigenetic Regulation of the Human Retinoblastoma Tumor Suppressor Gene Promoter by CTCF
Authors: De La Rosa-Velázquez Inti A. , Rincón-Arano Héctor , Benítez-Bribiesca Luis , Recillas-Targa Félix 
Published: March 2007

Abstract
Epigenetic misregulation is a more common feature in human cancer than previously anticipated. In the present investigation, we identified CCCTC-binding factor (CTCF), the multivalent 11-zinc-finger nuclear factor, as a regulator that favors a particular local chromatin conformation of the human retinoblastoma gene promoter. We show that its binding contributes to Rb gene promoter epigenetic stability. Ablation of the CTCF binding site from the human Rb gene promoter induced a rapid epigenetic silencing of reporter gene expression in an integrated genome context. CTCF DNA binding is methylation sensitive, and the methylated Rb-CTCF site is recognized by the Kaiso methyl-CpG–binding protein. This is the first evidence suggesting that CTCF protects the Rb gene promoter, a classic CpG island, against DNA methylation, and when such control region is abnormally methylated Kaiso, and probably its associated repressor complex, induce epigenetic silencing of the promoter. Our results identify CTCF as a novel epigenetic regulator of the human retinoblastoma gene promoter. [Cancer Res 2007;67(6):2577–85]
G-Rich Proto-Oncogenes Are Targeted for Genomic Instability in B-Cell Lymphomas
Authors: Duquette Michelle L. , Huber Michael D. , Maizels Nancy 
Published: March 2007

Abstract
Diffuse large B-cell lymphoma is the most common lymphoid malignancy in adults. It is a heterogeneous disease with variability in outcome. Genomic instability of a subset of proto-oncogenes, including c-MYC, BCL6, RhoH, PIM1, and PAX5, can contribute to initial tumor development and has been correlated with poor prognosis and aggressive tumor growth. Lymphomas in which these proto-oncogenes are unstable derive from germinal center B cells that express activation-induced deaminase (AID), the B-cell–specific factor that deaminates DNA to initiate immunoglobulin gene diversification. Proto-oncogene instability is evident as both aberrant hypermutation and translocation, paralleling programmed instability which diversifies the immunoglobulin loci. We have asked if genomic sequence correlates with instability in AID-positive B-cell lymphomas. We show that instability does not correlate with enrichment of the WRC sequence motif that is the consensus for deamination by AID. Instability does correlate with G-richness, evident as multiple runs of the base guanine on the nontemplate DNA strand. Extending previous analysis of c-MYC, we show experimentally that transcription of BCL6 and RhoH induces formation of structures, G-loops, which contain single-stranded regions targeted by AID. We further show that G-richness does not characterize translocation breakpoints in AID-negative B- and T-cell malignancies. These results identify G-richness as one feature of genomic structure that can contribute to genomic instability in AID-positive B-cell malignancies. [Cancer Res 2007;67(6):2586–94]
A Single Nucleotide Polymorphism in the MDM2 Gene Disrupts the Oscillation of p53 and MDM2 Levels in Cells
Authors: Hu Wenwei , Feng Zhaohui , Ma Lan , Wagner John , Rice J. Jeremy , Stolovitzky Gustavo , Levine Arnold J. 
Published: March 2007

Abstract
Oscillations of both p53 and MDM2 proteins have been observed in cells after exposure to stress. A mathematical model describing these oscillations predicted that oscillations occur only at selected levels of p53 and MDM2 proteins. This model prediction suggests that oscillations will disappear in cells containing high levels of MDM2 as observed with a single nucleotide polymorphism in the MDM2 gene (SNP309). The effect of SNP309 upon the p53-MDM2 oscillation was examined in various human cell lines and the oscillations were observed in the cells with at least one wild-type allele for SNP309 (T/T or T/G) but not in cells homozygous for SNP309 (G/G). Furthermore, estrogen preferentially stimulated the transcription of MDM2 from SNP309 G allele and increased the levels of MDM2 protein in estrogen-responsive cells homozygous for SNP309 (G/G). These results suggest the possibility that SNP309 G allele may contribute to gender-specific tumorigenesis through further elevating the MDM2 levels and disrupting the p53-MDM2 oscillation. Furthermore, using the H1299-HW24 cells expressing wild-type p53 under a tetracycline-regulated promoter, the p53-MDM2 oscillation was observed only when p53 levels were in a specific range, and DNA damage was found to be necessary for triggering the p53-MDM2 oscillation. This study shows that higher levels of MDM2 in cells homozygous for SNP309 (G/G) do not permit coordinated p53-MDM2 oscillation after stress, which might contribute to decreased efficiency of the p53 pathway and correlates with a clinical phenotype (i.e., the development of cancers at earlier age of onset in female). [Cancer Res 2007;67(6):2757–65]
Inactivation of Apc in the Mouse Prostate Causes Prostate Carcinoma
Authors: Bruxvoort Katia J. , Charbonneau Holli M. , Giambernardi Troy A. , Goolsby James C. , Qian Chao-Nan , Zylstra Cassandra R. , Robinson Daniel R. , Roy-Burman Pradip , Shaw Aubie K. , Buckner-Berghuis Bree D. , Sigler Robert E. , Resau James H. , Sullivan Ruth , Bushman Wade , Williams Bart O. 
Published: March 2007

Abstract
Alterations of the Wnt/β-catenin signaling pathway are positively associated with the development and progression of human cancer, including carcinoma of the prostate. To determine the role of activated Wnt/β-catenin signaling in mouse prostate carcinogenesis, we created a mouse prostate tumor model using probasin-Cre–mediated deletion of Apc. Prostate tumors induced by the deletion of Apc have elevated levels of β-catenin protein and are highly proliferative. Tumor formation is fully penetrant and follows a consistent pattern of progression. Hyperplasia is observed as early as 4.5 weeks of age, and adenocarcinoma is observed by 7 months. Continued tumor growth usually necessitated sacrifice between 12 and 15 months of age. Despite the high proliferation rate, we have not observed metastasis of these tumors to the lymph nodes or other organs. Surgical castration of 6-week-old mice inhibited tumor formation, and castration of mice with more advanced tumors resulted in the partial regression of specific prostate glands. However, significant areas of carcinoma remained 2 months postcastration, suggesting that tumors induced by Apc loss of function are capable of growth under conditions of androgen depletion. We conclude that the prostate-specific deletion of Apc and the increased expression of β-catenin associated with prostate carcinoma suggests a role for β-catenin in prostate cancer and offers an appropriate animal model to investigate the interaction of Wnt signaling with other genetic and epigenetic signals in prostate carcinogenesis. [Cancer Res 2007;67(6):2490–6]
Concomitant Activation of the JAK/STAT, PI3K/AKT, and ERK Signaling Is Involved in Leptin-Mediated Promotion of Invasion and Migration of Hepatocellular Carcinoma Cells
Authors: Saxena Neeraj K. , Sharma Dipali , Ding Xiaokun , Lin Songbai , Marra Fabio , Merlin Didier , Anania Frank A. 
Published: March 2007

Abstract
Various epidemiologic studies have shown that obesity is associated with hepatocellular carcinoma. Leptin, the key player in the regulation of energy balance and body weight control, also acts as a growth factor on certain organs in both normal and disease states. It is plausible that leptin acts to promote hepatocellular carcinogenesis directly affecting malignant properties of liver cancer cells. However, a direct role for leptin in hepatocellular carcinoma has not been shown. In this study, we analyzed the role of leptin and the mechanism(s) underlying its action in hepatocellular carcinoma cells, which express both short and long isoforms of leptin receptors. Treatment with leptin resulted in increased proliferation of both HepG2 and Huh7 cells and involves activation of signal transducers and activators of transcription 3 (STAT3), AKT, and extracellular signal-regulated kinase (ERK) signaling pathways. Leptin-induced phosphorylation of ERK and AKT was dependent on Janus-activated kinase (JAK)/STAT activation. Intriguingly, we also found that leptin potently induces invasion of hepatocellular carcinoma cells in Matrigel invasion and electric cell-substrate impedance-sensing assays. Leptin-stimulated invasion was effectively blocked by pharmacologic inhibitors of JAK/STAT and, to a lesser extent, by ERK and phosphatidylinositol 3-kinase (PI3K) inhibition. Importantly, leptin also induced the migration of both HepG2 and Huh7 cells on fibronectin matrix. Inhibition of JAK/STAT, ERK, and PI3K activation using pharmacologic inhibitors effectively blocked leptin-induced migration of HepG2 and Huh7 cells. Taken together, these data indicate that leptin promotes hepatocellular carcinoma growth, invasiveness, and migration and implicate the JAK/STAT pathway as a critical mediator of leptin action. Our findings have potential clinical implications for hepatocellular carcinoma progression in obese patients. [Cancer Res 2007;67(6):2497–507]
The Proteasome Inhibitor Bortezomib Acts Independently of p53 and Induces Cell Death via Apoptosis and Mitotic Catastrophe in B-Cell Lymphoma Cell Lines
Authors: Strauss Sandra J. , Higginbottom Karen , Jüliger Simone , Maharaj Lenushka , Allen Paul , Schenkein David , Lister T. Andrew , Joel Simon P. 
Published: March 2007

Abstract
Bortezomib is a proteasome inhibitor with proven efficacy in multiple myeloma and non–Hodgkin's lymphoma. This study reports the effects of bortezomib in B-cell lymphoma cell lines with differing sensitivity to bortezomib to investigate factors that influence sensitivity. Bortezomib induced a time- and concentration-dependent reduction in cell viability in five lymphoma cell lines, with EC50 values ranging from 6 nmol/L (DHL-7 cells) to 25 nmol/L (DHL-4 cells) after 72 h. Bortezomib cytotoxicity was independent of p53 function, as all cell lines exhibited mutations by sequence analysis. The difference in sensitivity was not explained by proteasome or nuclear factor-κB (NF-κB) inhibition as these were similar in the most and least sensitive cells. NF-κB inhibition was less marked than that of a specific NF-κB inhibitor, Bay 11-7082. Cell cycle analysis showed a marked G2-arrested population in the least sensitive DHL-4 line only, an effect that was not present with Bay 11-7082 treatment. Conversely, in DHL-7 cells, bortezomib treatment resulted in cells moving into an aberrant mitosis, indicative of mitotic catastrophe that may contribute to increased sensitivity to bortezomib. These studies show that although bortezomib treatment had similar effects on apoptotic and NF-κB signaling pathways in these cell lines, different cell cycle effects were observed and induction of a further mechanism of cell death, mitotic catastrophe, was observed in the more sensitive cell line, which may provide some pointers to the difference in sensitivity between cell lines. An improved understanding of how DHL-7 cells abrogate the G2-M cell cycle checkpoint may help identify targets to increase the efficacy of bortezomib. [Cancer Res 2007;67(6):2783–90]
Adrenomedullin Is Expressed in Pancreatic Cancer and Stimulates Cell Proliferation and Invasion in an Autocrine Manner via the Adrenomedullin Receptor, ADMR
Authors: Ramachandran Vijaya , Arumugam Thiruvengadam , Hwang Rosa F. , Greenson Joel K. , Simeone Diane M. , Logsdon Craig D. 
Published: March 2007

Abstract
The current study investigated adrenomedullin as a potential autocrine regulator of pancreatic cancer cell function. Adrenomedullin was localized in the neoplastic epithelium of 90% (43 of 48) of human pancreatic adenocarcinomas analyzed by immunohistochemistry and was expressed by 100% (8 of 8) of pancreatic cancer cell lines analyzed by reverse transcription-PCR. Pancreatic cancer cell lines also secreted adrenomedullin into the culture medium as determined by ELISA (5 of 5). Exogenous adrenomedullin treatment of Panc-1, BxPC3, and MPanc96 cells in vitro stimulated cell proliferation, invasion, and nuclear factor κB activity, indicating the ability of the cells to respond to adrenomedullin. Treatment of the cell cultures with an adrenomedullin antagonist inhibited basal levels of proliferation and nuclear factor κB activity, supporting the autocrine function of this molecule. Furthermore, increasing adrenomedullin levels by gene transfer to Panc-1 cells increased, whereas adrenomedullin small hairpin RNA silencing in MPanc96 cells inhibited tumor growth and metastasis in vivo. Adrenomedullin is able to act through at least two different receptors, adrenomedullin receptor (ADMR) and calcitonin receptor–like receptor (CRLR). Reverse transcription-PCR and Western blotting indicated that pancreatic cancer cells expressed only ADMR but not CRLR. In contrast, cells found in the tumor microenvironment, primary human pancreatic stellate and endothelial (HUVEC) cells, expressed both ADMR and CRLR. Small hairpin RNA silencing of ADMR in pancreatic cancer cells blocked adrenomedullin-induced growth and invasion, indicating that this receptor is involved in the autocrine actions of adrenomedullin. These data indicate that adrenomedullin acting via ADMR increases the aggressiveness of pancreatic cancer cells and suggests that these molecules may be useful therapeutic targets. [Cancer Res 2007;67(6):2666–75]
Long-term XPC Silencing Reduces DNA Double-Strand Break Repair
Authors: Despras Emmanuelle , Pfeiffer Petra , Salles Bernard , Calsou Patrick , Kuhfittig-Kulle Steffi , Angulo Jaime F. , Biard Denis S.F. 
Published: March 2007

Abstract
To study the relationships between different DNA repair pathways, we established a set of clones in which one specific DNA repair gene was silenced using long-term RNA interference in HeLa cell line. We focus here on genes involved in either nucleotide excision repair (XPA and XPC) or nonhomologous end joining (NHEJ; DNA-PKcs and XRCC4). As expected, XPAKD (knock down) and XPCKD cells were highly sensitive to UVC. DNA-PKcsKD and XRCC4KD cells presented an increased sensitivity to various inducers of double-strand breaks (DSBs) and a 70% to 80% reduction of in vitro NHEJ activity. Long-term silencing of XPC gene expression led to an increased sensitivity to etoposide, a topoisomerase II inhibitor that creates DSBs through the progression of DNA replication forks. XPCKD cells also showed intolerance toward acute γ-ray irradiation. We showed that XPCKD cells exhibited an altered spectrum of NHEJ products with decreased levels of intramolecular joined products. Moreover, in both XPCKD and DNA-PKcsKD cells, XRCC4 and ligase IV proteins were mobilized on damaged nuclear structures at lower doses of DSB inducer. In XPC-proficient cells, XPC protein was released from nuclear structures after induction of DSBs. By contrast, silencing of XPA gene expression did not have any effect on sensitivity to DSB or NHEJ. Our results suggest that XPC deficiency, certainly in combination with other genetic defects, may contribute to impair DSB repair. [Cancer Res 2007;67(6):2526–34]
Genetic Alterations in Mouse Medulloblastomas and Generation of TumorsDe novofrom Primary Cerebellar Granule Neuron Precursors
Authors: Zindy Frederique , Uziel Tamar , Ayrault Olivier , Calabrese Christopher , Valentine Marc , Rehg Jerold E. , Gilbertson Richard J. , Sherr Charles J. , Roussel Martine F. 
Published: March 2007

AbstractMice lacking p53 and one or two alleles of the cyclin D–dependent kinase inhibitor p18Ink4c are prone to medulloblastoma development. The tumor frequency is increased by exposing postnatal animals to ionizing radiation at a time when their cerebella are developing. In irradiated mice engineered to express a floxed p53 allele and a Nestin-Cre transgene, tumor development can be restricted to the brain. Analysis of these animals indicated that inactivation of one or both Ink4c alleles did not affect the time of medulloblastoma onset but increased tumor invasiveness. All such tumors exhibited complete loss of function of the Patched 1 (Ptc1) gene encoding the receptor for sonic hedgehog, and many exhibited other recurrent genetic alterations, including trisomy of chromosome 6, amplification of N-Myc, modest increases in copy number of the Ccnd1 gene encoding cyclin D1, and other complex chromosomal rearrangements. In contrast, medulloblastomas arising in Ptc1+/− mice lacking one or both Ink4c alleles retained p53 function and exhibited only limited genomic instability. Nonetheless, complete inactivation of the wild-type Ptc1 allele was a universal event, and trisomy of chromosome 6 was again frequent. The enforced expression of N-Myc or cyclin D1 in primary cerebellar granule neuron precursors isolated from Ink4c−/−, p53−/− mice enabled the cells to initiate medulloblastomas when injected back into the brains of immunocompromised recipient animals. These “engineered” tumors exhibited gene expression profiles indistinguishable from those of medulloblastomas that arose spontaneously. These results underscore the functional interplay between a network of specific genes that recurrently contribute to medulloblastoma formation. [Cancer Res 2007;67(6):2676–84]