bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation of HER2 by Cbl-Based Chimeric Ubiquitin Ligases
Authors: Li Xia , Shen Liangliang , Zhang Jing , Su Jin , Shen Lan , Liu Xinping , Han Hua , Han Wei , Yao Libo
Published: September 2007

Targeting disease-causing proteins for ubiquitination and degradation by chimeric molecules represents a promising alternative therapeutic strategy in cancer. Here, several Cbl-based chimeric ubiquitin ligases were recombined to achieve effective down-regulation of HER2. These chimeric molecules consisted of the Cbl NH2-terminal tyrosine kinase binding domain, linker, and RING domain, with the Src homology 2 domain replaced with that from growth factor receptor binding protein 2 (Grb2), Grb7, p85, or Src. The chimeric proteins not only interacted with HER2 but also enhanced the down-regulation of endogenous overexpressed HER2. After the chimeric proteins were introduced into HER2-overexpressing breast cancer SK-BR-3 cells or ovarian cancer SK-OV-3 cells, they effectively promoted HER2 ubiquitination and degradation in a RING finger domain–dependent manner. Consequently, expression of these chimeric molecules led to an inhibition of colony formation, increased the proportion of cells in the G1 cycle, and suppressed tumorigenicity. Collectively, our findings suggest that the Cbl-based chimeric ubiquitin ligases designed in the present study may represent a novel approach for the targeted therapy of HER2-overexpressing cancers. [Cancer Res 2007;67(18):8716–24]
Characterization of Viral Particles Isolated from Primary Cultures of Human Breast Cancer Cells
Authors: Melana Stella M. , Nepomnaschy Irene , Sakalian Michael , Abbott Andrea , Hasa Jennifer , Holland James F. , Pogo Beatriz G.T.
Published: September 2007

The association of human breast cancer with sequences similar to the mouse mammary tumor virus (MMTV) has been shown, but convincing evidence for the presence of viral particles in breast tumors has been lacking. We have described the complete proviral structure of a retrovirus in human breast cancer. This provirus, designated as human mammary tumor virus (HMTV), was 95% homologous to MMTV and revealed features of a replication-competent virus. We have therefore investigated the production of viral particles in primary cultures of human breast cancer (MSSM). Cells isolated from ascites or pleural effusions of patients with metastatic breast cancer contained viral sequences in their DNA, expressed Env protein, and showed retroviral particles by electron microscopy. Viral particles from culture media exhibited morphologic features of β-retroviruses sedimenting at buoyant densities of 1.12 to 1.18 g/mL in sucrose gradients and showed reverse transcriptase activity. cDNA sequences from virion RNA were synthesized, amplified, and sequenced and all the virion genes were detected and 70% of the virion RNA was sequenced. The sequence homologies were, respectively, 85% to 95% compared with the MMTV and HMTV proviruses we have previously described. These results clearly show that breast cancer cells in primary cultures produced HMTV viral particles that are similar to the mouse virus and which may play a role in human breast cancer pathogenesis. [Cancer Res 2007;67(18):8960–5]
PC-1/PrLZ Contributes to Malignant Progression in Prostate Cancer
Authors: Zhang Hui , Wang Jian , Pang Bo , Liang Rui-xia , Li Suping , Huang Pei-tang , Wang Ruoxiang , Chung Leland W.K. , Zhau Haiyen E. , Huang Cuifen , Zhou Jian-guang
Published: September 2007

PC-1/PrLZ gene overexpression has been identified to be associated with prostate cancer progression. Previous studies have revealed that PC-1 possesses transforming activity and confers malignant phenotypes to mouse NIH3T3 cells. However, the functional relevance of PC-1 expression changes during prostate cancer development and progression remains to be evaluated. In this study, gain-of-function and loss-of-function analyses in LNCaP and C4-2 cells, respectively, were implemented. Experimental data showed that PC-1 expression was in positive correlation with prostate cancer cell growth and anchor-independent colony formation in vitro, as well as tumorigenicity in athymic BALB/c mice. Moreover, PC-1 expression was also found to promote androgen-independent progression and androgen antagonist Casodex resistance in prostate cancer cells. These results indicate that PC-1 contributes to androgen-independent progression and malignant phenotypes in prostate cancer cells. Furthermore, molecular evidence revealed that PC-1 expression stimulated Akt/protein kinase B signaling pathway, which has been implicated to play important roles in promoting androgen refractory progression in prostate cancer. Increased PC-1 levels in C4-2 cells may represent an adaptive response in prostate cancer, mediating androgen-independent growth and malignant progression. Inhibiting PC-1 expression may represent a novel therapeutic strategy to delay prostate cancer progression. [Cancer Res 2007;67(18):8906–13]
The Requirement for DNAM-1, NKG2D, and NKp46 in the Natural Killer Cell-Mediated Killing of Myeloma Cells
Authors: El-Sherbiny Yasser M. , Meade Josephine L. , Holmes Tim D. , McGonagle Dennis , Mackie Sarah L. , Morgan Ann W. , Cook Gordon , Feyler Sylvia , Richards Stephen J. , Davies Faith E. , Morgan Gareth J. , Cook Graham P.
Published: September 2007

Recent evidence suggests a role for natural killer (NK) cells in the control of multiple myeloma. We show that expression of the NK cell receptor DNAM-1 (CD226) is reduced on CD56dim NK cells from myeloma patients with active disease compared with patients in remission and healthy controls. This suggested that this receptor might play a role in NK-myeloma interactions. The DNAM-1 ligands Nectin-2 (CD112) and the poliovirus receptor (PVR; CD155) were expressed by most patient myeloma samples analyzed. NK killing of patient-derived myelomas expressing PVR and/or Nectin-2 was DNAM-1 dependent, revealing a functional role for DNAM-1 in myeloma cell killing. In myeloma cell lines, cell surface expression of PVR was associated with low levels of NKG2D ligands, whereas cells expressing high levels of NKG2D ligands did not express PVR protein or mRNA. Furthermore, NK cell-mediated killing of myeloma cell lines was dependent on either DNAM-1 or NKG2D but not both molecules. In contrast, the natural cytotoxicity receptor NKp46 was required for the killing of all myeloma cell lines analyzed. Thus, DNAM-1 is important in the NK cell-mediated killing of myeloma cells expressing the cognate ligands. The importance of NKp46, NKG2D, and DNAM-1 in myeloma killing mirrors the differential expression of NK cell ligands by myeloma cells, reflecting immune selection during myeloma disease progression. [Cancer Res 2007;67(18):8444–9]
Nonclassic Functions of Human Topoisomerase I: Genome-Wide and Pharmacologic Analyses
Authors: Miao Ze-Hong , Player Audrey , Shankavaram Uma , Wang Yong-Hong , Zimonjic Drazen B. , Lorenzi Philip L. , Liao Zhi-Yong , Liu Hong , Shimura Tsutomu , Zhang Hong-Liang , Meng Ling-Hua , Zhang Yong-Wei , Kawasaki Ernest S. , Popescu Nicholas C. , Aladjem Mirit I. , Goldstein David J. , Weinstein John N. , Pommier Yves
Published: September 2007

The biological functions of nuclear topoisomerase I (Top1) have been difficult to study because knocking out TOP1 is lethal in metazoans. To reveal the functions of human Top1, we have generated stable Top1 small interfering RNA (siRNA) cell lines from colon and breast carcinomas (HCT116-siTop1 and MCF-7-siTop1, respectively). In those clones, Top1 is reduced ∼5-fold and Top2α compensates for Top1 deficiency. A prominent feature of the siTop1 cells is genomic instability, with chromosomal aberrations and histone γ-H2AX foci associated with replication defects. siTop1 cells also show rDNA and nucleolar alterations and increased nuclear volume. Genome-wide transcription profiling revealed 55 genes with consistent changes in siTop1 cells. Among them, asparagine synthetase (ASNS) expression was reduced in siTop1 cells and in cells with transient Top1 down-regulation. Conversely, Top1 complementation increased ASNS, indicating a causal link between Top1 and ASNS expression. Correspondingly, pharmacologic profiling showed l-asparaginase hypersensitivity in the siTop1 cells. Resistance to camptothecin, indenoisoquinoline, aphidicolin, hydroxyurea, and staurosporine and hypersensitivity to etoposide and actinomycin D show that Top1, in addition to being the target of camptothecins, also regulates DNA replication, rDNA stability, and apoptosis. Overall, our studies show the pleiotropic nature of human Top1 activities. In addition to its classic DNA nicking-closing functions, Top1 plays critical nonclassic roles in genomic stability, gene-specific transcription, and response to various anticancer agents. The reported cell lines and approaches described in this article provide new tools to perform detailed functional analyses related to Top1 function. [Cancer Res 2007;67(18):8752–61]
Nuclear Factor of Activated T3 Is a Negative Regulator of Ras-JNK1/2-AP-1–Induced Cell Transformation
Authors: Yao Ke , Cho Yong-Yeon , Bergen H. Robert , Madden Benjamin J. , Choi Bu Young , Ma Wei-Ya , Bode Ann M. , Dong Zigang
Published: September 2007

The c-jun-NH2-kinases (JNK) play a critical role in tumor promoter–induced cell transformation and apoptosis. Here, we showed that the nuclear factor of activated T3 (NFAT3) is phosphorylated by JNK1 or JNK2 at Ser213 and Ser217, which are located in the conserved SP motif. The transactivation domain of NFAT3 is found between amino acids (aa) 113 and 260 and includes the phosphorylation targets of JNK1 and JNK2. NFAT3 transactivation activity was suppressed in JNK1−/− or JNK2−/− mouse embryonic fibroblast (MEF) cells compared with wild-type MEF cells. Moreover, a 3xNFAT-luc reporter gene assay indicated that NFAT3 transcriptional activity was increased in a dose-dependent manner by JNK1 or JNK2. Double mutations at Ser213 and Ser217 suppressed NFAT3 transactivation activity; and SP600125, a JNK inhibitor, suppressed NFAT3-induced 3xNFAT-luciferase activity. Knockdown of JNK1 or JNK2 suppressed foci formation in NIH3T3 cells. Importantly, ectopic expression of NFAT3 inhibited AP-1 activity and suppressed foci formation. Furthermore, knockdown of NFAT3 enhanced Ras-JNK1 or JNK2-induced foci formation in NIH3T3 cells. Taken together, these results provided direct evidence for the anti-oncogenic potential of the NFAT3 transcription factor. [Cancer Res 2007;67(18):8725–35]
17β-Estradiol Up-regulates the Insulin-like Growth Factor Receptor through a Nongenotropic Pathway in Prostate Cancer Cells
Authors: Pandini Giuseppe , Genua Marco , Frasca Francesco , Squatrito Sebastiano , Vigneri Riccardo , Belfiore Antonino
Published: September 2007

Prostate carcinomas frequently express estrogen receptors (ER), irrespective of androgen receptor (AR) expression; however, the role of ERs and estrogens in prostate cancer is controversial. We found that 17β-estradiol (E2) is able to markedly up-regulate insulin-like growth factor (IGF)-I receptor (IGF-IR) mRNA and protein expression in both AR-positive (LNCaP cells) and AR-negative (PC-3 cells) prostate cancer cells. This effect occurs not only via ERα but also via ERβ stimulation and is specific for IGF-IR because it does not involve the cognate insulin receptor. IGF-IR up-regulation is associated with increased IGF-IR phosphorylation and with increased mitogenic and motogenic activities in response to IGF-I. IGF-IR up-regulation by E2 does not require ER binding to DNA and is poorly sensitive to antiestrogen blockade, whereas it is associated with the activation of cytosolic kinase cascades involving Src, extracellular signal–regulated kinase (ERK)-1/2, and, to a lesser extent, phosphatidylinositol 3-kinase and is sensitive to the inhibition of these kinases. In conclusion, our data indicate that estrogens may contribute to IGF system deregulation in prostate cancer through the activation of a nongenotropic pathway. Estrogens may have a role, therefore, in tumor progression to androgen independence. Inhibition of the IGF-IR or the Src-ERK pathway should be considered, therefore, as an adjuvant therapy in prostate cancer. [Cancer Res 2007;67(18):8932–41]
Knock-in of Mutant K-ras in Nontumorigenic Human Epithelial Cells as a New Model for Studying K-ras–Mediated Transformation
Authors: Konishi Hiroyuki , Karakas Bedri , Abukhdeir Abde M. , Lauring Josh , Gustin John P. , Garay Joseph P. , Konishi Yuko , Gallmeier Eike , Bachman Kurtis E. , Park Ben Ho
Published: September 2007

The oncogenic function of mutant ras in mammalian cells has been extensively investigated using multiple human and animal models. These systems include overexpression of exogenous mutant ras transgenes, conditionally expressed knock-in mouse models, and somatic cell knockout of mutant and wild-type ras genes in human cancer cell lines. However, phenotypic discrepancies between knock-in mice and transgenic mutant ras overexpression prompted us to evaluate the consequences of targeted knock-in of an oncogenic K-ras mutation in the nontumorigenic human breast epithelial cell line MCF-10A and hTERT-immortalized human mammary epithelial cells. Our results show several significant differences between mutant K-ras knock-in cells versus their transgene counterparts, including limited phosphorylation of the downstream molecules extracellular signal-regulated kinase and AKT, minor proliferative capacity in the absence of an exogenous growth factor, and the inability to form colonies in semisolid medium. Analysis of 16 cancer cell lines carrying mutant K-ras genes indicated that 50% of cancer cells harbor nonoverexpressed heterozygous K-ras mutations similar to the expression seen in our knock-in cell lines. Thus, this system serves as a new model for elucidating the oncogenic contribution of mutant K-ras as expressed in a large fraction of human cancer cells. [Cancer Res 2007;67(18):8460–7]
Increased Glioma Growth in Mice Depleted of Macrophages
Authors: Galarneau Hugo , Villeneuve Jérôme , Gowing Geneviève , Julien Jean-Pierre , Vallières Luc
Published: September 2007

Macrophages can promote the growth of some tumors, such as those of the breast and lung, but it is unknown whether this is true for all tumors, including those of the nervous system. On the contrary, we have previously shown that macrophages can slow the progression of malignant gliomas through a tumor necrosis factor–dependent mechanism. Here, we provide evidence suggesting that this antitumor effect could be mediated by T lymphocytes, as their number was drastically reduced in tumor necrosis factor–deficient mice and inversely correlated with glioma volume. However, this correlation was only observed in allogeneic recipients, prompting a reevaluation of the role of macrophages in a nonimmunogenic context. Using syngeneic mice expressing the herpes simplex virus thymidine kinase under the control of the CD11b promoter, we show that macrophages can exert an antitumor effect without the help of T lymphocytes. Macrophage depletion achieved by ganciclovir treatment resulted in a 33% increase in glioma volume. The antitumor effect of macrophages was not likely due to a tumoricidal activity because phagocytosis or apoptosis of glioma cells, transduced ex vivo with a lentiviral vector expressing green fluorescent protein, was rarely observed. Their antitumor effect was also not due to a destructive action on the tumor vasculature because macrophage depletion resulted in a modest reduction in vascular density. Therefore, this study suggests that macrophages can attenuate glioma growth by an unconventional mechanism. This study also validates a new transgenic model to explore the role of macrophages in cancer. [Cancer Res 2007;67(18):8874–81]
Histone Deacetylase Inhibitors Induce Cell Death Selectively in Cells That Harbor Activated kRasV12: The Role of Signal Transducers and Activators of Transcription 1 and p21
Authors: Klampfer Lidija , Huang Jie , Shirasawa Senji , Sasazuki Takehiko , Augenlicht Leonard
Published: September 2007

Histone deacetylase (HDAC) inhibitors (HDACi) show potent and selective antitumor activity despite the fact that they induce histone hyperacetylation in both normal and tumor cells. In this study, we showed that the inducible expression of kRasV12 in nontransformed intestinal epithelial cells significantly lowered the mitochondrial membrane potential (MMP) and sensitized cells to HDACi-induced apoptosis. Consistent with our finding that colon cancer cell lines with mutant Ras have reduced expression of signal transducers and activators of transcription 1 (STAT1), we showed that inducible expression of mutant Ras markedly decreased both basal and inducible expression of STAT1, a transcription factor with tumor suppressor activity. To investigate whether reduced expression of STAT1 in cells that harbor mutant Ras contributes to their increased sensitivity to HDACi, we silenced the expression of STAT1 in HKe-3 cells with small interfering RNA. Despite the fact that silencing of STAT1 was not sufficient to alter the MMP, STAT1 deficiency, like Ras mutations, sensitized cells to apoptosis induced by HDACi. We showed that the induction of p21 by HDACi was significantly impaired in HKe-3 cells with silenced STAT1 expression and showed that the ability of butyrate to activate p21 transcription was diminished in STAT1-deficient HKe-3 cells. Finally, we used cells with targeted deletion of p21 to confirm that p21 protects cells from butyrate-induced apoptosis, strongly suggesting that in these cells STAT1 deficiency promotes butyrate-induced apoptosis through impaired induction of p21. Our data therefore establish that Ras mutations, and consequent reduction in the expression of STAT1, underlie the increased susceptibility of transformed cells to undergo apoptosis in response to treatment with inhibitors of HDAC activity. [Cancer Res 2007;67(18):8477–85]
Tissue Inhibitor of Metalloproteinases-1 Promotes Liver Metastasis by Induction of Hepatocyte Growth Factor Signaling
Authors: Kopitz Charlotte , Gerg Michael , Bandapalli Obul Reddy , Ister Dilek , Pennington Caroline J. , Hauser Stephanie , Flechsig Christin , Krell Hans-Willi , Antolovic Dalibor , Brew Keith , Nagase Hideaki , Stangl Manfred , Hann von Weyhern Claus W. , Brücher Björn L.D.M. , Brand Karsten , Coussens Lisa M. , Edwards Dylan R. , Krüger Achim
Published: September 2007

Balanced expression of proteases and their inhibitors is one prerequisite of tissue homeostasis. Metastatic spread of tumor cells through the organism depends on proteolytic activity and is the death determinant for cancer patients. Paradoxically, increased expression of tissue inhibitor of metalloproteinases-1 (TIMP-1), a natural inhibitor of several endometalloproteinases, including matrix metalloproteinases and a disintegrin and metalloproteinase-10 (ADAM-10), in cancer patients is negatively correlated with their survival, although TIMP-1 itself inhibits invasion of some tumor cells. Here, we show that elevated stromal expression of TIMP-1 promotes liver metastasis in two independent tumor models by inducing the hepatocyte growth factor (HGF) signaling pathway and expression of several metastasis-associated genes, including HGF and HGF-activating proteases, in the liver. We also found in an in vitro assay that suppression of ADAM-10 is in principle able to prevent shedding of cMet, which may be one explanation for the increase of cell-associated HGF receptor cMet in livers with elevated TIMP-1. Similar TIMP-1–associated changes in gene expression were detected in livers of patients with metastatic colorectal cancer. The newly identified role of TIMP-1 to create a prometastatic niche may also explain the TIMP-1 paradoxon. [Cancer Res 2007;67(18):8615–23]
Eradication of Large Tumors in Mice by a Tritherapy Targeting the Innate, Adaptive, and Regulatory Components of the Immune System
Authors: Berraondo Pedro , Nouzé Clémence , Préville Xavier , Ladant Daniel , Leclerc Claude
Published: September 2007

Targeting the human papillomavirus (HPV) E7 antigen to dendritic cells with the adenylate cyclase (CyaA) of Bordetella pertussis as a vaccine vector led to potent therapeutic immune responses against TC-1 tumors in a murine model of cervical carcinoma induced by HPV. However, as the time between tumor graft and vaccination increased, the antitumor efficacy of the CyaA-E7 vaccine gradually decreased. The vaccine had no effect if the tumor diameter was >8 mm. Analyses of regulatory cells recruited during TC-1 tumor growth revealed a high number of splenic MDSCs and a large percentage of regulatory T cells, particularly in the tumor. Administration of a tritherapy including CpG complexed with a cationic lipid, low-dose cyclophosphamide, and the CyaA-E7 vaccine completely overcame tumor-associated immunosuppression and eradicated large, established tumors in almost all treated animals. This strong antitumor response was followed by a large expansion of regulatory T cells in tumor, spleen, and tumor-draining lymph nodes and of splenic neutrophils. These findings indicate that immunotherapeutic strategies that simultaneously target innate, adaptive, and regulatory components of the immune system are effective in the eradication of large tumors. [Cancer Res 2007;67(18):8847–55]
A Capsid-Modified, Conditionally Replicating Oncolytic Adenovirus Vector Expressing TRAIL Leads to Enhanced Cancer Cell Killing in Human Glioblastoma Models
Authors: Wohlfahrt Martin E. , Beard Brian C. , Lieber André , Kiem Hans-Peter
Published: September 2007

Glioblastoma multiforme (GBM) is the most aggressive brain tumor, and patients rarely survive for more than 2 years. Gene therapy may offer new treatment options and improve the prognosis for patients with GBM. Adenovirus-mediated gene therapy strategies for brain tumors have been limited by inefficient gene transfer due to low expression of the adenovirus serotype 5 (Ad5) receptor. We have used an adenovirus vector that specifically replicates in tumor cells and uses an Ad5 capsid and the adenovirus serotype (Ad35) fiber for efficient infection of malignant tumor cells. This vector also expresses adenovirus E1A and tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) in a tumor-specific manner. Here, we show that this oncolytic vector (Ad5/Ad35.IR-E1A/TRAIL) efficiently infects the GBM tumor cell lines SF767, T98G, and U-87 MG. Tumor cell killing was markedly enhanced with Ad5/Ad35.IR-E1A/TRAIL compared with wild-type Ad5 and Ad35 virus or Ad5/Ad35.IR-E1A- vectors without TRAIL expression in vitro. In vivo experiments using s.c. xenografted U-87 MG cells in NOD/SCID mice showed a significant growth delay of tumors after i.t. injection of Ad5/Ad35.IR-E1A/TRAIL, whereas adenovirus wild-type injections showed only marginal or no effect. Our findings indicate that the use of a capsid-modified adenoviral vector, in combination with TRAIL expression, is a promising novel approach for gene therapy of glioblastoma. [Cancer Res 2007;67(18):8783–90]
Identification and Biological Evaluation of a Novel and Potent Small Molecule Radiation Sensitizer via an Unbiased Screen of a Chemical Library
Authors: Lally Brian E. , Geiger Geoffrey A. , Kridel Steven , Arcury-Quandt Alice E. , Robbins Michael E. , Kock Nancy D. , Wheeler Kenneth , Peddi Prakash , Georgakilas Alexandros , Kao Gary D. , Koumenis Constantinos
Published: September 2007

For patients with solid tumors, the tolerance of surrounding tissues often limits the dose of radiation that can be delivered. Thus, agents that preferentially increase the cytotoxic effects of radiation toward tumor cells would significantly alter the therapeutic ratio and improve patient survival. Using a high-throughput, unbiased screening approach, we have identified 4′-bromo-3′-nitropropiophenone (NS-123) as a radiosensitizer of human glioma cells in vitro and in vivo. NS-123 radiosensitized U251 glioma cells in a dose-dependent and time-dependent manner, with dose enhancement ratios ranging from 1.3 to 2.0. HT-29 colorectal carcinoma and A549 lung adenocarcinoma cells were also radiosensitized by NS-123 in vitro, whereas NS-123 did not increase the radiation sensitivity of normal human astrocytes or developmental abnormalities or lethality of irradiated Zebrafish embryos. In a novel xenograft model of U251 cells implanted into Zebrafish embryos, NS-123 enhanced the tumor growth-inhibitory effects of ionizing radiation (IR) with no apparent effect on embryo development. Similar results were obtained using a mouse tumor xenograft model in which NS-123 sensitized U251 tumors to IR while exhibiting no overt toxicity. In vitro pretreatment with NS-123 resulted in accumulation of unrepaired IR-induced DNA strand breaks and prolonged phosphorylation of the surrogate markers of DNA damage H2AX, ataxia telangiectasia mutated protein, DNA-dependent protein kinase, and CHK2 after IR, suggesting that NS-123 inhibits a critical step in the DNA repair pathway. These results show the potential of this cell-based, high-throughput screening method to identify novel radiosensitizers and suggest that NS-123 and similar nitrophenol compounds may be effective in antiglioma modalities. [Cancer Res 2007;67(18):8791–9]
Membrane-Bound Heparin-Binding Epidermal Growth Factor–Like Growth Factor Regulates E-Cadherin Expression in Pancreatic Carcinoma Cells
Authors: Wang Fang , Sloss Callum , Zhang Xiaobo , Lee Sam W. , Cusack James C.
Published: September 2007

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the EGF growth factor family. Initially synthesized as a membrane-bound precursor (pro-HB-EGF), it is cleaved at the juxtamembrane domain to release the soluble form of HB-EGF (s-HB-EGF) by sheddases, including matrix metalloproteinases (MMP) and a disintegrin and metalloproteinases. This is a process referred to as ectodomain shedding and is implicated in the process of all ligands of the EGF receptor (EGFR) family. The tumorigenic potential of s-HB-EGF has been studied extensively; however, the role of pro-HB-EGF in tumor progression is unknown, despite the fact that a considerable amount of pro-HB-EGF remains on the cell membrane. Our data here clearly indicated the distinct role of pro-HB-EGF in the regulation of E-cadherin expression and the epithelial-mesenchymal transition. We showed here that the expression of pro-HB-EGF was associated with the differentiation status in pancreatic tumors and cell lines. Expression of noncleaved pro-HB-EGF in pancreatic cells resulted in the up-regulation of E-cadherin through suppression of ZEB1, which is a transcriptional repressor of E-cadherin. Inhibition of HB-EGF shedding using a MMP inhibitor, GM6001, also dramatically augmented the E-cadherin expression while suppressing the EGFR activation. Moreover, up-regulation of E-cadherin by pro-HB-EGF not only resulted in cellular morphologic change but also decreased cell motility and enhanced apoptotic sensitivity in response to gemcitabine-erlotinib treatment. Collectively, our data defined a distinct role of pro-HB-EGF in the regulation of E-cadherin, suggesting that inhibition of shedding may be a novel approach to suppress pancreatic metastasis and sensitize cells to cancer therapy. [Cancer Res 2007;67(18):8486–93]
The Role of S100P in the Invasion of Pancreatic Cancer Cells Is Mediated through Cytoskeletal Changes and Regulation of Cathepsin D
Authors: Whiteman Hannah J. , Weeks Mark E. , Dowen Sally E. , Barry Sayka , Timms John F. , Lemoine Nicholas R. , Crnogorac-Jurcevic Tatjana
Published: September 2007

Up-regulation of S100P, a member of the S100 calcium-binding protein family, is an early molecular event in the development of pancreatic cancer and it is expressed at high levels in both precursor lesions and invasive cancer. To gain more insight into the molecular mechanisms underlying the functional roles of this protein, we stably overexpressed S100P in the Panc1 pancreatic cancer cell line and identified the consequent changes in global protein expression by two-dimensional difference in-gel electrophoresis. The observed changes in target proteins were confirmed by Western blot analysis and immunofluorescence, whereas their functional effect was investigated using motility and invasion assays. In this study, we have shown that overexpression of S100P led to changes in the expression levels of several cytoskeletal proteins, including cytokeratins 8, 18, and 19. We have also shown disorganization of the actin cytoskeleton network and changes in the phosphorylation status of the actin regulatory protein cofilin. Additionally, we have shown that overexpression of S100P leads to increased expression of another early pancreatic cancer marker, S100A6, as well as the aspartic protease cathepsin D, both of which are involved in cellular invasion. Functional studies showed that the increased invasive potential of S100P-overexpressing cells was at least partially due to the increase in cathepsin D expression. In summary, our data suggest that these changes could contribute to the metastatic spread of pancreatic cancer and may explain the devastating prognosis of this disease. [Cancer Res 2007;67(18):8633–42]
Genomic Profiling Reveals Alternative Genetic Pathways of Prostate Tumorigenesis
Authors: Lapointe Jacques , Li Chunde , Giacomini Craig P. , Salari Keyan , Huang Stephanie , Wang Pei , Ferrari Michelle , Hernandez-Boussard Tina , Brooks James D. , Pollack Jonathan R.
Published: September 2007

Prostate cancer is clinically heterogeneous, ranging from indolent to lethal disease. Expression profiling previously defined three subtypes of prostate cancer, one (subtype-1) linked to clinically favorable behavior, and the others (subtypes-2 and -3) linked with a more aggressive form of the disease. To explore disease heterogeneity at the genomic level, we carried out array-based comparative genomic hybridization (array CGH) on 64 prostate tumor specimens, including 55 primary tumors and 9 pelvic lymph node metastases. Unsupervised cluster analysis of DNA copy number alterations (CNA) identified recurrent aberrations, including a 6q15-deletion group associated with subtype-1 gene expression patterns and decreased tumor recurrence. Supervised analysis further disclosed distinct patterns of CNA among gene-expression subtypes, where subtype-1 tumors exhibited characteristic deletions at 5q21 and 6q15, and subtype-2 cases harbored deletions at 8p21 (NKX3-1) and 21q22 (resulting in TMPRSS2-ERG fusion). Lymph node metastases, predominantly subtype-3, displayed overall higher frequencies of CNA, and in particular gains at 8q24 (MYC) and 16p13, and loss at 10q23 (PTEN) and 16q23. Our findings reveal that prostate cancers develop via a limited number of alternative preferred genetic pathways. The resultant molecular genetic subtypes provide a new framework for investigating prostate cancer biology and explain in part the clinical heterogeneity of the disease. [Cancer Res 2007;67(18):8504–10]
Fc Optimization of Therapeutic Antibodies Enhances Their Ability to Kill Tumor CellsIn vitroand Controls Tumor ExpansionIn vivovia Low-Affinity Activating Fcγ Receptors
Authors: Stavenhagen Jeffrey B. , Gorlatov Sergey , Tuaillon Nadine , Rankin Christopher T. , Li Hua , Burke Stephen , Huang Ling , Johnson Syd , Bonvini Ezio , Koenig Scott
Published: September 2007

Monoclonal antibodies (mAb) are widely used in the treatment of non-Hodgkin's lymphoma and autoimmune diseases. Although the mechanism of action in vivo is not always known, the therapeutic activity of several approved mAbs depends on the binding of the Fcγ regions to low-affinity Fcγ receptors (FcγR) expressed on effector cells. We did functional genetic screens to identify IgG1 Fc domains with improved binding to the low-affinity activating Fc receptor CD16A (FcγRIIIA) and reduced binding to the low-affinity inhibitory Fc receptor, CD32B (FcγRIIB). Identification of new amino acid residues important for FcγR binding guided the construction of an Fc domain that showed a dramatically enhanced CD16A binding and greater than a 100-fold improvement in antibody-dependent cell-mediated cytotoxicity. In a xenograft murine model of B-cell malignancy, the greatest enhancement of an Fc-optimized anti-human B-cell mAb was accounted for by improved binding to FcγRIV, a unique mouse activating FcγR that is expressed by monocytes and macrophages but not natural killer (NK) cells, consistent with experimental and clinical data suggesting that mononuclear phagocytes, effector cells expressing both activating and inhibitory FcγR, are critical mediators of B-cell depletion in vivo. By using mice transgenic for human CD16A, enhanced survival was observed due to expression of CD16A-158phe on monocytes and macrophages as well as on NK cells in these mice. The design of new generations of improved antibodies for immunotherapy should aim at Fc optimization to increase the engagement of activating FcγR present on the surface of tumor-infiltrating effector cell populations. [Cancer Res 2007;67(18):8882–90]
Expansion of Human T Regulatory Type 1 Cells in the Microenvironment of Cyclooxygenase 2 Overexpressing Head and Neck Squamous Cell Carcinoma
Authors: Bergmann Christoph , Strauss Laura , Zeidler Reinhard , Lang Stephan , Whiteside Theresa L.
Published: September 2007

Cyclooxygenase 2 (COX-2) overexpression and production of prostaglandin E2 (PGE2) by head and neck squamous cell carcinomas (HNSCC) induce type 1 regulatory T (Tr1) cells and contribute to carcinogenesis by creating a tolerogenic milieu. To test this hypothesis, CD4+CD25− T cells obtained from the peripheral blood of 10 normal donors were cocultured with autologous dendritic cells, irradiated HNSCC cells and cytokines, interleukin 2 (IL-2), IL-10, and IL-15. HNSCC cells were either COX-2 negative, constitutively expressed COX-2, were transfected with COX-2, or had COX-2 expression knocked down by small interfering RNA. Other modifications included coculture plus or minus the COX-inhibitor, Diclofenac, or synthetic PGE2 in the absence of HNSCC. Lymphocytes proliferating in 10-day cocultures were phenotyped by flow cytometry, studied for cytokine production by ELISA and for suppressor function in CFSE inhibition assays plus or minus anti–IL-10 or anti–transforming growth factor-β1 (TGF-β1) monoclonal antibodies (mAb). COX-2+ HNSCC or exogenous PGE2 induced outgrowth of Tr1 cells with the CD3+CD4+CD25−IL2Rβ+IL2Rγ+FoxP3+CTLA-4+IL-10+TGF-β1+IL-4− phenotype and high suppressor functions (range, 46–68%). Small interfering RNA knockout of COX-2 gene in HNSCC led to outgrowth of lymphocytes with decreased IL2Rγ (P = 0.0001), FoxP3 (P = 0.05), and IL-10 (P = 0.035) expression and low suppressor activity (range, 26–34%). Whereas COX-2+ cocultures contained IL-10 and TGF-β1 (medians, 615 and 824 pg/mL), cytokine levels were decreased (P < 0.0001) in COX-2− cocultures. Inhibition of COX-2 enzymatic activity in HNSCC abrogated outgrowth of Tr1 cells. Neutralizing mAbs to IL-10 and/or TGF-β1 abolished Tr1-mediated suppression. COX-2 overexpression in HNSCC plays a major role in the induction of Tr1 cells in the tumor microenvironment. [Cancer Res 2007;67(18):8865–73]
Mixed Lineage Leukemia Translocations and a Leukemia Stem Cell Program
Authors: Faber Joerg , Armstrong Scott A.
Published: September 2007

Cancer stem cells (CSC) may provide the self-renewal capacity required to sustain a tumor. One possibility is that CSC arise from the stem cell counterparts in normal tissues. Alternatively, CSC may arise from more differentiated progenitor cells found in certain tissues. In support of this idea, we showed recently that mixed lineage leukemia fusion oncoproteins can convert committed hematopoietic progenitors into leukemias, which include leukemia stem cells expressing a self-renewal associated program in the context of a differentiated myeloid cell. The findings suggest a basis to understand the pathobiology of CSC and possible strategies to attack them to undermine the self-renewal capacity of a tumor. [Cancer Res 2007;67(18):8425–8]
Transforming Growth Factor-β Can Suppress Tumorigenesis through Effects on the Putative Cancer Stem or Early Progenitor Cell and Committed Progeny in a Breast Cancer Xenograft Model
Authors: Tang Binwu , Yoo Naomi , Vu Mary , Mamura Mizuko , Nam Jeong-Seok , Ooshima Akira , Du Zhijun , Desprez Pierre-Yves , Anver Miriam R. , Michalowska Aleksandra M. , Shih Joanna , Parks W. Tony , Wakefield Lalage M.
Published: September 2007

The transforming growth factor-β (TGF-β) pathway has tumor-suppressor activity in many epithelial tissues. Because TGF-β is a potent inhibitor of epithelial cell proliferation, it has been widely assumed that this property underlies the tumor-suppressor effect. Here, we have used a xenograft model of breast cancer to show that endogenous TGF-β has the potential to suppress tumorigenesis through a novel mechanism, involving effects at two distinct levels in the hierarchy of cellular progeny that make up the epithelial component of the tumor. First, TGF-β reduces the size of the putative cancer stem or early progenitor cell population, and second it promotes differentiation of a more committed, but highly proliferative, progenitor cell population to an intrinsically less proliferative state. We further show that reduced expression of the type II TGF-β receptor correlates with loss of luminal differentiation in a clinical breast cancer cohort, suggesting that this mechanism may be clinically relevant. At a molecular level, the induction of differentiation by TGF-β involves down-regulation of Id1, and forced overexpression of Id1 can promote tumorigenesis despite persistence of the antiproliferative effect of TGF-β. These data suggest new roles for the TGF-β pathway in regulating tumor cell dynamics that are independent of direct effects on proliferation. [Cancer Res 2007;67(18):8643–52]
Ultradeep Bisulfite Sequencing Analysis of DNA Methylation Patterns in Multiple Gene Promoters by 454 Sequencing
Authors: Taylor Kristen H. , Kramer Robin S. , Davis J. Wade , Guo Juyuan , Duff Deiter J. , Xu Dong , Caldwell Charles W. , Shi Huidong
Published: September 2007

We developed a novel approach for conducting multisample, multigene, ultradeep bisulfite sequencing analysis of DNA methylation patterns in clinical samples. A massively parallel sequencing-by-synthesis method (454 sequencing) was used to directly sequence >100 bisulfite PCR products in a single sequencing run without subcloning. We showed the utility, robustness, and superiority of this approach by analyzing methylation in 25 gene-related CpG rich regions from >40 cases of primary cells, including normal peripheral blood lymphocytes, acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), and mantle cell lymphoma (MCL). A total of 294,631 sequences was generated with an average read length of 131 bp. On average, >1,600 individual sequences were generated for each PCR amplicon far beyond the few clones (<20) typically analyzed by traditional bisulfite sequencing. Comprehensive analysis of CpG methylation patterns at a single DNA molecule level using clustering algorithms revealed differential methylation patterns between diseases. A significant increase in methylation was detected in ALL and FL samples compared with CLL and MCL. Furthermore, a progressive spreading of methylation was detected from the periphery toward the center of select CpG islands in the ALL and FL samples. The ultradeep sequencing also allowed simultaneous analysis of genetic and epigenetic data and revealed an association between a single nucleotide polymorphism and the methylation present in the LRP1B promoter. This new generation of methylome sequencing will provide digital profiles of aberrant DNA methylation for individual human cancers and offers a robust method for the epigenetic classification of tumor subtypes. [Cancer Res 2007;67(18):8511–8]
Mechanisms Involved in Synergistic Anticancer Immunity of Anti-4-1BB and Anti-CD4 Therapy
Authors: Choi Beom K. , Kim Young H. , Kang Woo J. , Lee Sun K. , Kim Kwang H. , Shin Su M. , Yokoyama Wayne M. , Kim Tae Y. , Kwon Byoung S.
Published: September 2007

Anti-4-1BB–mediated anticancer effects were potentiated by depletion of CD4+ cells in B16F10 melanoma-bearing C57BL/6 mice. Anti-4-1BB induced the expansion and differentiation of polyclonal tumor-specific CD8+ T cells into IFN-γ–producing CD11c+CD8+ T cells. The CD4+ cell depletion was responsible for facilitating immune cell infiltration into tumor tissues and removing some regulatory barriers such as T regulatory and indoleamine-2,3-dioxygenase (IDO)+ dendritic cells. Both monoclonal antibodies (mAb) contributed to the efficient induction of MHC class I molecules on the tumor cells in vivo. The effectors that mediated the anti-4-1BB effect were NKG2D+KLRG1+CD11c+CD8+ T cells that accumulated preferentially in the tumor tissues. Blocking NKG2D reduced the therapeutic effect by 20% to 26%, which may indicate that NKG2D contributes partially to tumor killing by the differentiated CD8+ T cells. Our results indicate that the combination of the two mAbs, agonistic anti-4-1BB and depleting anti-CD4, results in enhanced production of efficient tumor-killing CTLs, facilitation of their infiltration, and production of a susceptible tumor microenvironment. [Cancer Res 2007;67(18):8891–9]
Induction of Protective CTL Immunity against Peptide Transporter TAP-Deficient Tumors through Dendritic Cell Vaccination
Authors: Chambers Benedict , Grufman Per , Fredriksson Vanoohi , Andersson Kenth , Roseboom Marjet , Laban Sandra , Camps Marcel , Wolpert Elisabeth Z. , Wiertz Emmanuel J.H.J. , Offringa Rienk , Ljunggren Hans-Gustaf , van Hall Thorbald
Published: September 2007

A large proportion of human cancers show deficiencies in the MHC class I antigen-processing machinery. Such defects render tumors resistant to immune eradication by tumoricidal CTLs. We recently identified a unique population of CTL that selectively targets tumor immune-escape variants through recognition of MHC-presented peptides, termed TEIPP (T cell epitopes associated with impaired peptide processing), expressed on cells lacking functional TAP-peptide transporters. Previously, we showed that vaccination with TEIPP peptides mediates protection against TAP-deficient tumors. Here, we further explored the concept of TEIPP-targeted therapy using a dendritic cell (DC)–based cellular vaccine. Impairment of TAP function in DC induced the presentation of endogenous TEIPP antigens by MHC class I molecules, and immunization with these DCs protected mice against the outgrowth of TAP-deficient lymphomas and fibrosarcomas. Immune analysis of vaccinated mice revealed strong TEIPP-specific CTL responses, and a crucial role for CD8+ cells in tumor resistance. Finally, we show that TEIPP antigens could be successfully induced in wild-type DC by introducing the viral TAP inhibitor UL49.5. Our results imply that immune intervention strategies with TAP-inhibited DC could be developed for the treatment of antigen processing–deficient cancers in humans. [Cancer Res 2007;67(18):8450–5]
Differential Expression and Function of Caveolin-1 in Human Gastric Cancer Progression
Authors: Burgermeister Elke , Xing Xiangbin , Röcken Christoph , Juhasz Mark , Chen Jie , Hiber Michaela , Mair Katrin , Shatz Maria , Liscovitch Moti , Schmid Roland M. , Ebert Matthias P.A.
Published: September 2007

Caveolin-1 is a scaffold protein of caveolae that acts as a tumor modulator by interacting with cell adhesion molecules and signaling receptors. The role of caveolin-1 in the pathogenesis of gastric cancer (GC) is currently unknown. We show by confocal immunofluorescence microscopy and immunohistochemistry of biopsies from GC patients (n = 41) that the nonneoplastic mucosa expressed caveolin-1 in foveolar epithelial cells and adjacent connective tissue. GC cells of only 3 of 41 (7%) patients expressed caveolin-1 and were all of the intestinal type. Quantitative PCR and Western blotting confirmed that, compared with nonneoplastic tissue, the overall caveolin-1 mRNA was decreased in 14 of 19 (74%) GC patients and protein in 7 of 13 (54%), respectively. Strong caveolin-1 reactivity was found in the nonepithelial compartment (myocytes, fibroblasts, perineural, and endothelial cells) in both tumor-free and GC samples. In a series of human GC cell lines, caveolin-1 expression was low in cells derived from a primary tumor (AGS and SNU-1) but was increased in cell lines originating from distant metastases (MKN-7, MKN-45, NCI-N87, KATO-III, and SNU-5). Ectopic expression of caveolin-1 in AGS cells decreased proliferation but promoted anchorage-independent growth and survival. RNAi-mediated knockdown of endogenous caveolin-1 in MKN-45 cells accelerated cell growth. These data indicate that caveolin-1 exhibits a stage-dependent differential expression and function in GC and may thereby contribute to its pathogenesis. [Cancer Res 2007;67(18):8519–26]
Knock-in of Oncogenic Kras Does Not Transform Mouse Somatic Cells But Triggers a Transcriptional Response that Classifies Human Cancers
Authors: Arena Sabrina , Isella Claudio , Martini Miriam , de Marco Ario , Medico Enzo , Bardelli Alberto
Published: September 2007

KRAS mutations are present at a high frequency in human cancers. The development of therapies targeting mutated KRAS requires cellular and animal preclinical models. We exploited adeno-associated virus–mediated homologous recombination to insert the Kras G12D allele in the genome of mouse somatic cells. Heterozygous mutant cells displayed a constitutively active Kras protein, marked morphologic changes, increased proliferation and motility but were not transformed. On the contrary, mouse cells in which we overexpressed the corresponding Kras cDNA were readily transformed. The levels of Kras activation in knock-in cells were comparable with those present in human cancer cells carrying the corresponding mutation. Kras-mutated cells were compared with their wild-type counterparts by gene expression profiling, leading to the definition of a “mutated Kras-KI signature” of 345 genes. This signature was capable of classifying mouse and human cancers according to their KRAS mutational status, with an accuracy similar to or better than published Ras signatures. The isogenic cells that we have developed recapitulate the oncogenic activation of KRAS occurring in cancer and represent new models for studying Kras-mediated transformation. Our results have implications for the identification of human tumors in which the oncogenic KRAS transcriptional response is activated and suggest new strategies to build mouse models of tumor progression. [Cancer Res 2007;67(18):8468–76]