bluuebunny/crossref_metadata_2025 huggingface dataset:
PCOTH, a Novel Gene Overexpressed in Prostate Cancers, Promotes Prostate Cancer Cell Growth through Phosphorylation of Oncoprotein TAF-Iβ/SET
Authors: Anazawa Yoshio , Nakagawa Hidewaki , Furihara Mutsuo , Ashida Shingo , Tamura Kenji , Yoshioka Hiroki , Shuin Taro , Fujioka Tomoaki , Katagiri Toyomasa , Nakamura Yusuke
Published: September 2005

Through genome-wide cDNA microarray analysis coupled with microdissection of prostate cancer cells, we identified a novel gene, prostate collagen triple helix (PCOTH), showing overexpression in prostate cancer cells and its precursor cells, prostatic intraepithelial neoplasia (PIN). Immunohistochemical analysis using polyclonal anti-PCOTH antibody confirmed elevated expression of PCOTH, a 100-amino-acid protein containing collagen triple-helix repeats, in prostate cancer cells and PINs. Knocking down PCOTH expression by small interfering RNA (siRNA) resulted in drastic attenuation of prostate cancer cell growth, and concordantly, LNCaP derivative cells that were designed to constitutively express exogenous PCOTH showed higher growth rate than LNCaP cells transfected with mock vector, suggesting the growth-promoting effect of PCOTH on prostate cancer cell. To investigate the biological mechanisms of this growth-promoting effect, we applied two-dimensional differential gel electrophoresis (2D-DIGE) to analyze the phospho-protein fractions in LNCaP cells transfected with PCOTH. We found that the phosphorylation level of oncoprotein TAF-Iβ/SET was significantly elevated in LNCaP cells transfected with PCOTH than control LNCaP cells, and these findings were confirmed by Western blotting and in-gel kinase assay. Furthermore, knockdown of endogenous TAF-Iβ expression by siRNA also attenuated viability of prostate cancer cells as well. These findings suggest that PCOTH is involved in growth and survival of prostate cancer cells thorough, in parts, the TAF-Iβ pathway, and that this molecule should be a promising target for development of new therapeutic strategies for prostate cancers.
Bcl-2 Promotes Invasion and Lung Metastasis by Inducing Matrix Metalloproteinase-2
Authors: Choi Jihyung , Choi Kyusam , Benveniste Etty N. , Hong Young-Sook , Lee Je-Ho , Kim Jhingook , Park Kyoungsook
Published: September 2005

Bcl-2 is involved in the progression of human malignancies, but the precise role and mechanism of Bcl-2 for tumor invasion and metastasis remains unclear. In this study, we have investigated the role and mechanism of Bcl-2 on tumor cell invasion and metastasis by using Bcl-2 overexpressing non–small cell lung cancer cells. Matrix metalloproteinases (MMPs) are important proteins involved in the processes of tumor invasion and metastasis. In vitro Matrigel invasion assays showed that Bcl-2 overexpression increased tumor cell invasion by 15-fold. Moreover, Bcl-2 overexpression enhanced in vivo lung metastasis by 4-fold. Consistent with its effect on invasion and metastasis, Bcl-2 overexpression induced not only MMP-2 mRNA and its protein expression, but this also activated the pro-MMP-2 protein to its active form. To explore the induction mechanism of MMP-2 by Bcl-2, we investigated the effects of Bcl-2 overexpression on MMP-2 transcriptional regulation. Nuclear run-on assays showed a 6-fold increase in the transcription rate of MMP-2 mRNA in the Bcl-2 transfectants (H157/Bcl-2) compared with that of the H157/vector control cells (H157/C). Overexpression of Bcl-2 induced the nuclear transcription factor activator protein 1 family, including the c-Jun, JunD, c-Fos, FosB, and Fra-1 proteins. Reporter assays combined with deletion mutagenesis analysis and gel shift assays showed the involvement of activator protein 1 in the activation of MMP-2 promoter activity by Bcl-2. Taken together, we have shown that Bcl-2 promotes tumor invasion and lung metastasis by inducing MMP-2 gene expression through the combined action of transcriptional and posttranslational mechanisms.
Tumor Development by Transgenic Expression of a Constitutively Active Insulin-Like Growth Factor I Receptor
Authors: Carboni Joan M. , Lee Adrian V. , Hadsell Darryl L. , Rowley Bruce R. , Lee Francis Y. , Bol David K. , Camuso Amy E. , Gottardis Marco , Greer Ann F. , Ho Ching Ping , Hurlburt Warren , Li Aixin , Saulnier Mark , Velaparthi Upender , Wang Cindy , Wen Mei-Li , Westhouse Richard A. , Wittman Mark , Zimmermann Kurt , Rupnow Brent A. , Wong Tai W.
Published: September 2005

The insulin-like growth factor I receptor (IGF-IR) is a transmembrane tyrosine kinase that is essential to growth and development and also thought to provide a survival signal for the maintenance of the transformed phenotype. There has been increasing interest in further understanding the role of IGF-I signaling in cancer and in developing receptor antagonists for therapeutic application. We describe herein a novel animal model that involves transgenic expression of a fusion receptor that is constitutively activated by homodimerization. Transgenic mice that expressed the activated receptor showed aberrant development of the mammary glands and developed salivary and mammary adenocarcinomas as early as 8 weeks of age. Xenograft tumors and a cell line were derived from the transgenic animals and are sensitive to inhibition by a novel small-molecule inhibitor of the IGF-IR kinase. This new model should provide new opportunities for further understanding how aberrant IGF-IR signaling leads to tumorigenesis and for optimizing novel antagonists of the receptor kinase.
Inhibition of the Phosphatidylinositol 3-Kinase/Akt/Mammalian Target of Rapamycin Pathway but not the MEK/ERK Pathway Attenuates Laminin-Mediated Small Cell Lung Cancer Cellular Survival and Resistance to Imatinib Mesylate or Chemotherapy
Authors: Tsurutani Junji , West Kip A. , Sayyah Jacqueline , Gills Joell J. , Dennis Phillip A.
Published: September 2005

The fact that small cell lung cancer (SCLC) is commonly incurable despite being initially responsive to chemotherapy, combined with disappointing results from a recent SCLC clinical trial with imatinib, has intensified efforts to identify mechanisms of SCLC resistance. Adhesion to extracellular matrix (ECM) is one mechanism that can increase therapeutic resistance in SCLC cells. To address whether adhesion to ECM increases resistance through modulation of signaling pathways, a series of SCLC cell lines were plated on various ECM components, and activation of two signaling pathways that promote cellular survival, the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway and the mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) pathway, was assessed. Although differential activation was observed, adhesion to laminin increased Akt activation, increased cellular survival after serum starvation, and caused the cells to assume a flattened, epithelial morphology. Inhibitors of the PI3K/Akt/mTOR pathway (LY294002, rapamycin) but not the MEK/ERK pathway (U0126) abrogated laminin-mediated survival. SCLC cells plated on laminin were not only resistant to serum starvation–induced apoptosis but were also resistant to apoptosis caused by imatinib. Combining imatinib with LY294002 or rapamycin but not U0126 caused greater than additive increases in apoptosis compared with apoptosis caused by the inhibitor or imatinib alone. Similar results were observed when adenoviruses expressing mutant Akt were combined with imatinib, or when LY294002 was combined with cisplatin or etoposide. These studies identify laminin-mediated activation of the PI3K/Akt/mTOR pathway as a mechanism of cellular survival and therapeutic resistance in SCLC cells and suggest that inhibition of the PI3K/Akt/mTOR pathway is one strategy to overcome SCLC resistance mediated by ECM.
Elevated Serum Levels of CC Thymus and Activation-Related Chemokine (TARC) in Primary Hodgkin's Disease: Potential for a Prognostic Factor
Authors: Weihrauch Martin R. , Manzke Oliver , Beyer Marc , Haverkamp Heinz , Diehl Volker , Bohlen Heribert , Wolf Juergen , Schultze Joachim L.
Published: September 2005

The CC thymus and activation-related chemokine (TARC) is a protein, which is highly expressed by Reed-Sternberg cells in Hodgkin's disease and is found in the majority of Hodgkin's disease patients. Within several trials conducted by the German Hodgkin study group, 62 Hodgkin's disease patients were elected based on availability of serum samples post and prior therapy to assess TARC levels by ELISA. TARC levels from 33 patients with continuous complete response (CCR), 20 patients with relapse, and nine patients with progressive disease (PD) were correlated with freedom from treatment failure and survival. As defined in healthy donors (mean value ± 2× SD), a TARC level of >500 pg/mL was considered as elevated. The median TARC levels of all patients at baseline and after completed primary treatment were 5,803 pg/mL (range, 116-73,074 pg/mL) and 663 pg/mL (50-24,709 pg/mL), respectively. TARC levels of patients with PD were higher than those of patients with CCR at baseline and after therapy. Baseline TARC correlated significantly with stage (P = 0.019), erythrocyte sedimentation rate (P = 0.004), leukocyte count (P < 0.001), and lymphocyte count (P = 0.026). A TARC level of >2,000 pg/mL after completed treatment was a significant risk factor for poorer survival (P = 0.02) but not for relapse. In conclusion, monitoring serum TARC levels in Hodgkin's disease patients may add valuable information about therapy success in Hodgkin's disease patients, especially those with PD and should therefore be prospectively evaluated in future trials.
Using a Xenograft Model of Human Breast Cancer Metastasis to Find Genes Associated with Clinically Aggressive Disease
Authors: Kluger Harriet M. , Chelouche Lev Dina , Kluger Yuval , McCarthy Mary M. , Kiriakova Galina , Camp Robert L. , Rimm David L. , Price Janet E.
Published: September 2005

Metastasis is the primary cause of death from breast cancer. A xenograft model was used to identify genes potentially involved with metastasis, comparing expression in the poorly metastatic GI101A human breast cancer cell line and a highly metastatic variant, GILM2. cDNA microarray analyses of these isogenic variants were done using 16K Operon 70-mer oligonucleotide microarray slides. Differentially expressed genes were identified by ANOVA, and differences of ≥2.5-fold were found for 106 genes. Changes in protein or RNA expression were confirmed for 10 of 12 genes. Three markers, heat shock protein 70 (HSP-70), chemokine (C-X-C motif) ligand 1 (CXCL-1), and secreted leukocyte protease inhibitor (SLPI), were studied further with breast cancer tissue microarrays using a novel method of automated quantitative analysis. This uses cytokeratin to define pixels as breast cancer (tumor mask) within the tissue array spot and then measures intensity of marker expression using a cyanine 5–conjugated antibody within the mask. Scores were correlated with clinicopathologic variables. High HSP-70 expression and high nuclear CXCL-1 expression in primary tumors were both associated with decreased survival (P = 0.05 and 0.027, respectively). Expression of each marker was strongly associated with lymph node involvement (P = 0.0002, 0.008, 0.0012, and 0.012 for HSP-70, nuclear CXCL-1, cytoplasmic CXCL-1, and SLPI, respectively). Identification of genes associated with metastasis in experimental models may have clinical implications for the management of breast cancer, because some of these are associated with lymph node metastasis and survival and might be useful as prognostic markers or molecular targets for novel therapies.
The Prostaglandin E2 Receptor EP2 Is Required for Cyclooxygenase 2–Mediated Mammary Hyperplasia
Authors: Chang Sung-Hee , Ai Youxi , Breyer Richard M. , Lane Timothy F. , Hla Timothy
Published: September 2005

Expression of cyclooxygenase 2 (COX-2) in breast cancer correlates with poor prognosis, and COX-2 enzyme inhibitors reduce breast cancer incidence in humans. We recently showed that COX-2 overexpression in the mammary gland of transgenic mice induced mammary cancer. Because prostaglandin E2 (PGE2) is the major eicosanoid and because the EP2 subtype of the PGE2 receptor is highly expressed in the mammary tumors, we tested if this G protein–coupled receptor is required for tumorigenesis. We crossed the MMTV-COX-2 transgenic mice with Ep2−/− mice and studied tumor development in bigenic mice. Lack of EP2 receptor strongly suppressed COX-2–induced effects such as precocious development of the mammary gland in virgins and the development of mammary hyperplasia in multiparous female mice. Interestingly, the expression of amphiregulin, a potent mammary epithelial cell growth factor was down regulated in mammary glands of Ep2−/− mice. Total cyclic AMP (cAMP) levels were reduced in Ep2−/− mammary glands suggesting that PGE2 signaling via the EP2 receptor activates the Gs/cAMP/protein kinase A pathway. In mammary tumor cell lines, expression of the EP2 receptor followed by treatment with CAY10399, an EP2-specific agonist, strongly induced amphiregulin mRNA levels in a protein kinase A–dependent manner. These data suggest that PGE2 signaling via the EP2 receptor in mammary epithelial cells regulate mammary gland hyperplasia by the cAMP-dependent induction of amphiregulin. Inhibition of the EP2 pathway in the mammary gland may be a novel approach in the prevention and/or treatment of mammary cancer.
Tumor Cyclooxygenase-2/Prostaglandin E2–Dependent Promotion of FOXP3 Expression and CD4+CD25+ T Regulatory Cell Activities in Lung Cancer
Authors: Sharma Sherven , Yang Seok-Chul , Zhu Li , Reckamp Karen , Gardner Brian , Baratelli Felicita , Huang Min , Batra Raj K. , Dubinett Steven M.
Published: September 2005

Cyclooxygenase (COX)-2 and its product prostaglandin (PG) E2 underlie an immunosuppressive network that is important in the pathogenesis of non–small cell lung cancer. CD4+CD25+ T regulatory (Treg) cells play an important role in maintenance of immunologic self-tolerance. CD4+CD25+ Treg cell activities increase in lung cancer and appear to play a role in suppressing antitumor immune responses. Definition of the pathways controlling Treg cell activities will enhance our understanding of limitation of the host antitumor immune responses. Tumor-derived COX-2/PGE2 induced expression of the Treg cell-specific transcription factor, Foxp3, and increased Treg cell activity. Assessment of E-prostanoid (EP) receptor requirements revealed that PGE2-mediated induction of Treg cell Foxp3 gene expression was significantly reduced in the absence of the EP4 receptor and ablated in the absence of the EP2 receptor expression. In vivo, COX-2 inhibition reduced Treg cell frequency and activity, attenuated Foxp3 expression in tumor-infiltrating lymphocytes, and decreased tumor burden. Transfer of Treg cells or administration of PGE2 to mice receiving COX-2 inhibitors reversed these effects. We conclude that inhibition of COX-2/PGE2 suppresses Treg cell activity and enhances antitumor responses.
Differentiation of Human Embryonal Carcinomas In vitro and In vivo Reveals Expression Profiles Relevant to Normal Development
Authors: Skotheim Rolf I. , Lind Guro E. , Monni Outi , Nesland Jahn M. , Abeler Vera M. , Fosså Sophie D. , Duale Nur , Brunborg Gunnar , Kallioniemi Olli , Andrews Peter W. , Lothe Ragnhild A.
Published: September 2005

Embryonal carcinoma is a histologic subgroup of testicular germ cell tumors (TGCTs), and its cells may follow differentiation lineages in a manner similar to early embryogenesis. To acquire new knowledge about the transcriptional programs operating in this tumor development model, we used 22k oligo DNA microarrays to analyze normal and neoplastic tissue samples from human testis. Additionally, retinoic acid–induced in vitro differentiation was studied in relevant cell lines. We identified genes characterizing each of the known histologic subtypes, adding up to a total set of 687 differentially expressed genes. Among these, there was a significant overrepresentation of gene categories, such as genomic imprinting and gene transcripts associated to embryonic stem cells. Selection for genes highly expressed in the undifferentiated embryonal carcinomas resulted in the identification of 58 genes, including pluripotency markers, such as the homeobox genes NANOG and POU5F1 (OCT3/4), as well as GAL, DPPA4, and NALP7. Interestingly, abundant expression of several of the pluripotency genes was also detected in precursor lesions and seminomas. By use of tissue microarrays containing 510 clinical testicular samples, GAL and POU5F1 were up-regulated in TGCT also at the protein level and hence validated as diagnostic markers for undifferentiated tumor cells. The present study shows the unique gene expression profiles of each histologic subtype of TGCT from which we have identified deregulated components in selected processes operating in normal development, such as WNT signaling and DNA methylation.
Convection-Enhanced Drug Delivery: Increased Efficacy and Magnetic Resonance Image Monitoring
Authors: Mardor Yael , Rahav Ofer , Zauberman Yacov , Lidar Zvi , Ocherashvilli Aharon , Daniels Dianne , Roth Yiftach , Maier Stephan E. , Orenstein Arie , Ram Zvi
Published: September 2005

Convection-enhanced drug delivery (CED) is a novel approach to directly deliver drugs into brain tissue and brain tumors. It is based on delivering a continuous infusion of drugs via intracranial catheters, enabling convective distribution of high drug concentrations over large volumes of the target tissue while avoiding systemic toxicity. Efficient formation of convection depends on various physical and physiologic variables. Previous convection-based clinical trials showed significant diversity in the extent of convection among patients and drugs. Monitoring convection has proven to be an essential, yet difficult task. The current study describes the application of magnetic resonance imaging for immediate assessment of convection efficiency and early assessment of cytotoxic tissue response in a rat brain model. Immediate assessment of infusate distribution was obtained by mixing Gd-diethylenetriaminepentaacetic acid in the infusate prior to infusion. Early assessment of cytotoxic tissue response was obtained by subsequent diffusion-weighted magnetic resonance imaging. In addition, the latter imaging methodologies were used to establish the correlation between CED extent and infusate's viscosity. It was found that low-viscosity infusates tend to backflow along the catheter track, whereas high-viscosity infusates tend to form efficient convection. These results suggest that CED formation and extent may be significantly improved by increasing the infusate's viscosities, thus increasing treatment effects.
Phosphorylation of Histone H3 at Serine 10 Is Indispensable for Neoplastic Cell Transformation
Authors: Choi Hong Seok , Choi Bu Young , Cho Yong-Yeon , Mizuno Hideya , Kang Bong Seok , Bode Ann M. , Dong Zigang
Published: September 2005

Very little is known about the role of histone H3 phosphorylation in malignant transformation and cancer development. Here, we examine the function of H3 phosphorylation in cell transformation in vivo. Introduction of small interfering RNA-H3 into JB6 cells resulted in decreased epidermal growth factor (EGF)–induced cell transformation. In contrast, wild-type histone H3 (H3 WT)–overexpressing cells markedly stimulated EGF-induced cell transformation, whereas the H3 mutant S10A cells suppressed transformation. When H3 WT was overexpressed, EGF induction of c-fos and c-jun promoter activity was significantly increased compared with control cells but not in the H3 mutant S10A or S28A cells. In addition, activator protein-1 activity in H3 WT–overexpressing cells was markedly up-regulated by EGF in contrast to the H3 mutant S10A or S28A cells. These results indicate that the phosphorylation of histone H3 at Ser10 is an essential regulatory mechanism for EGF-induced neoplastic cell transformation.
Prostaglandin E2 Activates Mitogen-Activated Protein Kinase/Erk Pathway Signaling and Cell Proliferation in Non–Small Cell Lung Cancer Cells in an Epidermal Growth Factor Receptor–Independent Manner
Authors: Krysan Kostyantyn , Reckamp Karen L. , Dalwadi Harnisha , Sharma Sherven , Rozengurt Enrique , Dohadwala Mariam , Dubinett Steven M.
Published: September 2005

Cyclooxygenase 2 (COX-2) overexpression is found in a wide variety of human cancers and is linked to all stages of tumorigenesis. Elevated tumor COX-2 expression is associated with increased angiogenesis, tumor invasion, suppression of host immunity and promotes tumor cell resistance to apoptosis. Previous reports have linked the COX-2 product prostaglandin E2 (PGE2) to the abnormal activation of the mitogen-activated protein kinase/Erk kinase pathway. Here we show that PGE2 is able to rapidly stimulate Erk phosphorylation in a subset of non–small cell lung cancer (NSCLC) cell lines. This effect is not evident in bronchial epithelial cells. In contrast to previous reports in colon cancer, we found that Erk activation as well as cellular proliferation induced by PGE2 was not inhibited by pretreatment of the cells with epidermal growth factor receptor (EGFR) inhibitors. Activation of the Erk pathway by PGE2 was also resistant to src kinase inhibitors but sensitive to the protein kinase C inhibition. PGE2 effects are mediated through four G protein–coupled receptors. Selective inhibition of EP receptors revealed the possible involvement of Ca2+-dependent signaling in PGE2-mediated activation of Erk. Our data indicate the presence of an EGFR-independent activation of the mitogen-activated protein kinase/Erk pathway by PGE2 in NSCLC cells. These findings provide evidence for the possible link between tumor COX-2 overexpression and elevated Erk-mediated cancer cell proliferation and migration. Importantly, these findings suggest that COX-2 overexpression may contribute to EGFR inhibitor resistance in NSCLC.
N-Acetylcysteine Conjugate of Phenethyl Isothiocyanate Enhances Apoptosis in Growth-Stimulated Human Lung Cells
Authors: Yang Yang-Ming , Jhanwar-Uniyal Meena , Schwartz Joel , Conaway C. Clifford , Halicka H. Dorota , Traganos Frank , Chung Fung-Lung
Published: September 2005

We previously showed that dietary treatment with the N-acetylcysteine conjugate of phenethyl isothiocyanate (PEITC-NAC) inhibited benzo(a)pyrene-induced lung tumorigenesis in A/J mice, and that tumor inhibition was associated with induction of activator protein-1 (AP-1) activity and stimulation of apoptosis in the lungs of mice. In the present study, we show that PEITC-NAC also induces apoptosis and AP-1 activity in human lung adenocarcinoma A549 cells, and that activation of AP-1 is important in PEITC-NAC induced apoptosis in these cells. PEITC-NAC induced AP-1 binding activity in A549 cells in a dose- and time-dependent manner; peak activity appeared at 10 μmol/L after 24 hours. At that time, flow cytometric analysis showed a sub-G1 peak, indicating that ∼4.5% of the cells had undergone apoptosis. When wild-type c-jun cDNA was transfected into A549 cells, PEITC-NAC–mediated apoptosis was greatly increased in the c-jun–transfected cells compared with the control vector–transfected cells, based on cell morphology and analysis of DNA fragmentation. Furthermore, cells that were pretreated with 100 nmol/L 12-O-tetradecanoyl phorbol-13-acetate, and then treated with 25 μmol/L PEITC-NAC, underwent enhanced apoptosis compared with cells that were treated with PEITC-NAC alone; cells treated with 12-O-tetradecanoyl phorbol-13-acetate alone showed active cell growth without apoptosis. Bivariate flow cytometric analysis of DNA strand breaks versus DNA content showed that apoptosis induced by PEITC-NAC occurred predominantly in the G2-M phase. These findings suggest that growth-stimulated cells with an elevated basal AP-1 activity, i.e., A549 cells transfected with wild-type c-jun or treated with a tumor promoter, were more sensitive to PEITC-NAC–mediated apoptosis. The observation that PEITC-NAC induces apoptosis predominantly in growth-promoted cells, such as neoplastic cells, suggests a selective mechanism by which PEITC-NAC inhibits lung carcinogenesis.
Calcium/Calmodulin-Dependent Kinase I and Calcium/Calmodulin-Dependent Kinase Kinase Participate in the Control of Cell Cycle Progression in MCF-7 Human Breast Cancer Cells
Authors: Rodriguez-Mora Oswaldo G. , LaHair Michelle M. , McCubrey James A. , Franklin Richard A.
Published: September 2005

Calcium is universally required for cell growth and proliferation. Calmodulin is the main intracellular receptor for calcium. Although calcium and calmodulin are well known to be required for cell cycle regulation, the target pathways for their action remain poorly defined. Potential targets include the calcium/calmodulin-dependent kinases (CaM-K). The aim of this study was to determine the role of the CaM-Ks on cell proliferation and progress through the cell cycle in breast cancer cells. CaM-KI inhibition with either KN-93 or specific interfering RNA (siRNA) caused an arrest in the cell cycle in the human breast cancer cell line, MCF-7. This arrest occurred in the G1 phase of the cell cycle. Supporting this finding, CaM-K inhibition using KN-93 also resulted in a reduction of cyclin D1 protein and pRb phosphorylation when cells were compared with control cultures. Furthermore, inhibition of the upstream activator of CaM-KI, CaM-KK, using siRNA also resulted in cell cycle arrest. In summary, CaM-KK and CaM-KI participate in the control of the G0-G1 restriction check point of the cell cycle in human breast cancer cells. This arrest seems due to an inhibition in cyclin D1 synthesis and a reduction in pRb phosphorylation. To the best of our knowledge, this is the first time that CaM-KK has been reported to be involved in mammalian cell cycle regulation and that CaM-Ks are regulating breast cancer cell cycle.
MicroRNA Biogenesis and Cancer
Authors: Gregory Richard I. , Shiekhattar Ramin
Published: September 2005

MicroRNAs (miRNA) are a recently discovered family of short non–protein-coding RNAs that negatively regulate gene expression. Recent studies of miRNAs highlight a requirement for cell viability. Posttranscriptional silencing of target genes by miRNAs occurs either by targeting specific cleavage of homologous mRNAs, or by targeting specific inhibition of protein synthesis. We recently identified a multisubunit protein complex termed Microprocessor that is necessary and sufficient for processing miRNA precursor RNAs. Microprocessor contains Drosha, an RNase III endonuclease, and DGCR8, a gene deleted in DiGeorge syndrome. We consider recent findings that link miRNA perturbation to cancer.
Element Array by Scanning X-ray Fluorescence Microscopy after Cis-Diamminedichloro-Platinum(II) Treatment
Authors: Shimura Mari , Saito Akira , Matsuyama Satoshi , Sakuma Takahiro , Terui Yasuhito , Ueno Kazumasa , Yumoto Hirokatsu , Yamauchi Kazuto , Yamamura Kazuya , Mimura Hidekazu , Sano Yasuhisa , Yabashi Makina , Tamasaku Kenji , Nishio Kazuto , Nishino Yoshinori , Endo Katsuyoshi , Hatake Kiyohiko , Mori Yuzo , Ishizaka Yukihito , Ishikawa Tetsuya
Published: September 2005

Minerals are important for cellular functions, such as transcription and enzyme activity, and are also involved in the metabolism of anticancer chemotherapeutic compounds. Profiling of intracellular elements in individual cells could help in understanding the mechanism of drug resistance in tumors and possibly provide a new strategy of anticancer chemotherapy. Using a recently developed technique of scanning X-ray fluorescence microscopy (SXFM), we analyzed intracellular elements after treatment with cis-diamminedichloro-platinum(II) (CDDP), a platinum-based anticancer agent. The images obtained by SXFM (element array) revealed that the average Pt content of CDDP-resistant cells was 2.6 times less than that of sensitive cells, and the zinc content was inversely correlated with the intracellular Pt content. Data suggested that Zn-related detoxification is responsible for resistance to CDDP. Of Zn-related excretion factors, glutathione was highly correlated with the amount of Zn. The combined treatment of CDDP and a Zn(II) chelator resulted in the incorporation of thrice more Pt with the concomitant down-regulation of glutathione. We propose that the generation of an element array by SXFM opens up new avenues in cancer biology and treatment.
A Bifunctional Targeted Peptide that Blocks HER-2 Tyrosine Kinase and Disables Mitochondrial Function in HER-2-Positive Carcinoma Cells
Authors: Fantin Valeria R. , Berardi Marcelo J. , Babbe Holger , Michelman Montserrat V. , Manning Charlene M. , Leder Philip
Published: September 2005

The HER-2 oncoprotein is commonly overexpressed in a variety of human malignancies and has become an attractive antitumor target. A number of strategies to inhibit the HER-2 receptor tyrosine kinase are currently the focus of intensive preclinical and clinical research. In the present study, we have engineered a bifunctional peptide, BHAP, which consists of two modular domains: a HER-2-targeting/neutralizing domain and a mitochondriotoxic, proapoptotic domain. The chimeric peptide is biologically active and capable of selectively triggering apoptosis of HER-2-overexpressing cancer cells in culture, even those previously described as Herceptin resistant. Furthermore, BHAP slows down growth of HER-2-overexpressing human mammary xenografts established in SCID mice. This approach can be extended to the development of tailored targeted chimeric peptides against a number of overexpressed cellular receptors implicated in the development and progression of cancer.
Inhibition of Lymphogenous Metastasis Using Adeno-Associated Virus-Mediated Gene Transfer of a Soluble VEGFR-3 Decoy Receptor
Authors: Lin JianMin , Lalani Alshad S. , Harding Thomas C. , Gonzalez Melissa , Wu Wei-Wei , Luan Bo , Tu Guang Huan , Koprivnikar Kathryn , VanRoey Melinda J. , He Yulong , Alitalo Kari , Jooss Karin
Published: September 2005

The presence of metastases in regional lymph nodes is a strong indicator of poor patient survival in many types of cancer. It has recently been shown that the lymphangiogenic growth factor, vascular endothelial growth factor-C (VEGF-C), and its receptor, VEGF receptor-3 (VEGFR3), may play a pivotal role in the promotion of metastasis to regional lymph nodes. In this study, human prostate and melanoma tumor models that preferentially metastasize to the lymph nodes following s.c. tumor cell implantation were established from lymph node metastases via in vivo selection. Melanoma tumor cell sublines established from lymph node metastasis express higher amounts of VEGF-C than the parental tumor cells. The inhibition of tumor-derived VEGF-C with a soluble VEGFR3 decoy receptor, sVEGFR3-Fc, expressed via a recombinant adeno-associated viral vector, potently blocks tumor-associated lymphangiogenesis and tumor metastasis to the lymph nodes, when the treatment was initiated before the tumor implantation. In addition, sVEGFR3-Fc serum levels required for efficient blockade of lymph node metastases are strictly dependent on the VEGF-C levels generated by the primary tumor. Recombinant adeno-associated virus–mediated gene transfer of sVEGFR3-Fc may represent a feasible therapeutic strategy for blockade of lymphogenous metastasis.
Major Vault Protein, in Concert with Constitutively Photomorphogenic 1, Negatively Regulates c-Jun–Mediated Activator Protein 1 Transcription in Mammalian Cells
Authors: Yi Chunling , Li Shuting , Chen Xishu , Wiemer Erik A.C. , Wang Jian , Wei Ning , Deng Xing Wang
Published: September 2005

Constitutively photomorphogenic 1 (COP1), a RING finger ubiquitin ligase with substrates including c-Jun and p53, was recently found to be overexpressed in a number of breast and ovarian tumor samples. In addition to its E3 activity, COP1 was also shown to be able to inhibit activator protein 1 (AP-1) transcription. Through an affinity purification method, we have identified major vault protein (MVP) as a novel interacting partner for COP1 in mammalian cells. MVP, also known as lung resistance protein, is the main component of a ribonucleoprotein organelle called vault, and has been implicated in multiple drug resistance in many cancer cell lines and primary tumor samples. The interaction between COP1 and MVP is detectable at the endogenous level and occurs mostly in the cytoplasm. Similar to COP1, MVP inhibits c-Jun accumulation and AP-1 transcription activity. MVP knockout or knockdown cells contain elevated amount of c-Jun and increased AP-1 transcription activity. UV irradiation enhances MVP tyrosine phosphorylation, causes dissociation of COP1 from MVP, and alleviates the inhibitory activity of MVP on AP-1 transcription. Taken together, we propose that MVP, most likely through its interaction with COP1, suppresses c-Jun–mediated AP-1 transcription under unstressed conditions, thereby preventing cells from undergoing stress response.
Multiepitope HER2 Targeting Enhances Photoimmunotherapy of HER2-Overexpressing Cancer Cells with Pyropheophorbide-a Immunoconjugates
Authors: Savellano Mark D. , Pogue Brian W. , Hoopes P. Jack , Vitetta Ellen S. , Paulsen Keith D.
Published: September 2005

Multitargeting strategies improve the efficacy of antibody and immunotoxin therapies but have not yet been thoroughly explored for HER2-based cancer treatments. We investigated multiepitope HER2 targeting to boost photosensitizer immunoconjugate uptake as a way of enhancing photoimmunotherapy. Photoimmunotherapy may allow targeted photodynamic destruction of malignancies and may also potentiate anticancer antibodies. However, one obstacle preventing its clinical use is the delivery of enough photosensitizer immunoconjugates to target cells. Anti-HER2 photosensitizer immunoconjugates were constructed from two monoclonal antibodies (mAb), HER50 and HER66, using a novel method originally developed to label photosensitizer immunoconjugates with the photosensitizer, benzoporphyrin derivative verteporfin. Photosensitizer immunoconjugates were labeled instead with a promising alternative photosensitizer, pyropheophorbide-a (PPa), which required only minor changes to the conjugation procedure. Uptake and phototoxicity experiments using human cancer cells were conducted with the photosensitizer immunoconjugates and, for comparison, with free PPa. SK-BR-3 and SK-OV-3 cells served as HER2-overexpressing target cells. MDA-MB-468 cells served as HER2-nonexpressing control cells. Photosensitizer immunoconjugates with PPa/mAb molar ratios up to ∼10 specifically targeted and photodynamically killed HER2-overexpressing cells. On a per mole basis, photosensitizer immunoconjugates were less phototoxic than free PPa, but photosensitizer immunoconjugates were selective for target cells whereas free PPa was not. Multiepitope targeted photoimmunotherapy with a HER50 and HER66 photosensitizer immunoconjugate mixture was significantly more effective than single-epitope targeted photoimmunotherapy with a single anti-HER2 photosensitizer immunoconjugate, provided photosensitizer immunoconjugate binding was saturated. This study shows that multiepitope targeting enhances HER2-targeted photoimmunotherapy and maintains a high degree of specificity. Consequently, it seems that multitargeted photoimmunotherapy should also be useful against cancers that overexpress other receptors.
Three-dimensional High-Frequency Ultrasound Imaging for Longitudinal Evaluation of Liver Metastases in Preclinical Models
Authors: Graham Kevin C. , Wirtzfeld Lauren A. , MacKenzie Lisa T. , Postenka Carl O. , Groom Alan C. , MacDonald Ian C. , Fenster Aaron , Lacefield James C. , Chambers Ann F.
Published: September 2005

Liver metastasis is a clinically significant contributor to the mortality associated with melanoma, colon, and breast cancer. Preclinical mouse models are essential to the study of liver metastasis, yet their utility has been limited by the inability to study this dynamic process in a noninvasive and longitudinal manner. This study shows that three-dimensional high-frequency ultrasound can be used to noninvasively track the growth of liver metastases and evaluate potential chemotherapeutics in experimental liver metastasis models. Liver metastases produced by mesenteric vein injection of B16F1 (murine melanoma), PAP2 (murine H-ras–transformed fibroblast), HT-29 (human colon carcinoma), and MDA-MB-435/HAL (human breast carcinoma) cells were identified and tracked longitudinally. Tumor size and location were verified by histologic evaluation. Tumor volumes were calculated from the three-dimensional volumetric data, with individual liver metastases showing exponential growth. The importance of volumetric imaging to reduce uncertainty in tumor volume measurement was shown by comparing three-dimensional segmented volumes with volumes estimated from diameter measurements and the assumption of an ellipsoid shape. The utility of high-frequency ultrasound imaging in the evaluation of therapeutic interventions was established with a doxorubicin treatment trial. These results show that three-dimensional high-frequency ultrasound imaging may be particularly well suited for the quantitative assessment of metastatic progression and the evaluation of chemotherapeutics in preclinical liver metastasis models.
A Molecular Classification of Papillary Renal Cell Carcinoma
Authors: Yang Ximing J. , Tan Min-Han , Kim Hyung L. , Ditlev Jonathon A. , Betten Mark W. , Png Carolina E. , Kort Eric J. , Futami Kunihiko , Furge Kyle A. , Takahashi Masayuki , Kanayama Hiro-omi , Tan Puay Hoon , Teh Bin Sing , Luan Chunyan , Wang Kim , Pins Michael , Tretiakova Maria , Anema John , Kahnoski Richard , Nicol Theresa , Stadler Walter , Vogelzang Nicholas G. , Amato Robert , Seligson David , Figlin Robert , Belldegrun Arie , Rogers Craig G. , Teh Bin Tean
Published: September 2005

Despite the moderate incidence of papillary renal cell carcinoma (PRCC), there is a disproportionately limited understanding of its underlying genetic programs. There is no effective therapy for metastatic PRCC, and patients are often excluded from kidney cancer trials. A morphologic classification of PRCC into type 1 and 2 tumors has been recently proposed, but its biological relevance remains uncertain. We studied the gene expression profiles of 34 cases of PRCC using Affymetrix HGU133 Plus 2.0 arrays (54,675 probe sets) using both unsupervised and supervised analyses. Comparative genomic microarray analysis was used to infer cytogenetic aberrations, and pathways were ranked with a curated database. Expression of selected genes was validated by immunohistochemistry in 34 samples with 15 independent tumors. We identified two highly distinct molecular PRCC subclasses with morphologic correlation. The first class, with excellent survival, corresponded to three histologic subtypes: type 1, low-grade type 2, and mixed type 1/low-grade type 2 tumors. The second class, with poor survival, corresponded to high-grade type 2 tumors (n = 11). Dysregulation of G1-S and G2-M checkpoint genes were found in class 1 and 2 tumors, respectively, alongside characteristic chromosomal aberrations. We identified a seven-transcript predictor that classified samples on cross-validation with 97% accuracy. Immunohistochemistry confirmed high expression of cytokeratin 7 in class 1 tumors and of topoisomerase IIα in class 2 tumors. We report two molecular subclasses of PRCC, which are biologically and clinically distinct and may be readily distinguished in a clinical setting.
RNA Interference–Mediated Silencing of the Acetyl-CoA-Carboxylase-α Gene Induces Growth Inhibition and Apoptosis of Prostate Cancer Cells
Authors: Brusselmans Koen , De Schrijver Ellen , Verhoeven Guido , Swinnen Johannes V.
Published: September 2005

Overexpression of lipogenic enzymes is a common characteristic of many cancers. Thus far, studies aimed at the exploration of lipogenic enzymes as targets for cancer intervention have focused on fatty acid synthase (FAS), the enzyme catalyzing the terminal steps in fatty acid synthesis. Chemical inhibition or RNA interference (RNAi)–mediated knockdown of FAS consistently inhibits the growth and induces death of cancer cells. Accumulation of the FAS substrate malonyl-CoA has been implicated in the mechanism of cytotoxicity of FAS inhibition. Here, using RNAi technology, we have knocked down the expression of acetyl-CoA carboxylase-α (ACC-α), the enzyme providing the malonyl-CoA substrate. Silencing of the ACC-α gene resulted in a similar inhibition of cell proliferation and induction of caspase-mediated apoptosis of highly lipogenic LNCaP prostate cancer cells as observed after FAS RNAi. In nonmalignant cells with low lipogenic activity, no cytotoxic effects of knockdown of ACC-α or FAS were observed. These findings indicate that accumulation of malonyl-CoA is not a prerequisite for cytotoxicity induced by inhibition of tumor-associated lipogenesis and suggest that in addition to FAS, ACC-α is a potential target for cancer intervention.
Proteomic Characterization of the Angiogenesis Inhibitor SU6668 Reveals Multiple Impacts on Cellular Kinase Signaling
Authors: Godl Klaus , Gruss Oliver J. , Eickhoff Jan , Wissing Josef , Blencke Stephanie , Weber Martina , Degen Heidrun , Brehmer Dirk , Őrfi László , Horváth Zoltán , Kéri György , Müller Stefan , Cotten Matt , Ullrich Axel , Daub Henrik
Published: September 2005

Knowledge about molecular drug action is critical for the development of protein kinase inhibitors for cancer therapy. Here, we establish a chemical proteomic approach to profile the anticancer drug SU6668, which was originally designed as a selective inhibitor of receptor tyrosine kinases involved in tumor vascularization. By employing immobilized SU6668 for the affinity capture of cellular drug targets in combination with mass spectrometry, we identified previously unknown targets of SU6668 including Aurora kinases and TANK-binding kinase 1. Importantly, a cell cycle block induced by SU6668 could be attributed to inhibition of Aurora kinase activity. Moreover, SU6668 potently suppressed antiviral and inflammatory responses by interfering with TANK-binding kinase 1–mediated signal transmission. These results show the potential of chemical proteomics to provide rationales for the development of potent kinase inhibitors, which combine rather unexpected biological modes of action by simultaneously targeting defined sets of both serine/threonine and tyrosine kinases involved in cancer progression.
Novel Tumor-Specific Isoforms of BEHAB/Brevican Identified in Human Malignant Gliomas
Authors: Viapiano Mariano S. , Bi Wenya Linda , Piepmeier Joseph , Hockfield Susan , Matthews Russell T.
Published: September 2005

Malignant gliomas are deadly brain tumors characterized by diffuse invasion into the surrounding brain tissue. Understanding the mechanisms involved in glioma invasion could lead to new therapeutic strategies. We have previously shown that BEHAB/brevican, an extracellular matrix protein in the central nervous system, plays a role in the invasive ability of gliomas. The mechanisms that underlie BEHAB/brevican function are not yet understood, due in part to the existence of several isoforms that may have different functions. Here we describe for the first time the expression of BEHAB/brevican in human brain and characterize two novel glioma-specific isoforms, B/bsia and B/bΔg, which are generated by differential glycosylation and are absent from normal adult brain and other neuropathologies. B/bsia is an oversialylated isoform expressed by about half the high- and low-grade gliomas analyzed. B/bΔg lacks most of the carbohydrates typically present on BEHAB/brevican and is the major up-regulated isoform of this protein in high-grade gliomas but is absent in a specific subset of low-grade, indolent oligodendrogliomas. B/bΔg is detected on the extracellular surface, where it binds to the membrane by a mechanism distinct from the other BEHAB/brevican isoforms. The glioma-specific expression of B/bΔg, its restricted membrane localization, and its expression in all high-grade gliomas tested to date suggest that it may play a significant role in glioma progression and make it an important new potential therapeutic target. In addition, its absence from benign gliomas prompts its use as a diagnostic marker to distinguish primary brain tumors of similar histology but different pathologic course.
BLM Helicase Complements Disrupted Type II Telomere Lengthening in Telomerase-Negative sgs1 Yeast
Authors: Lillard-Wetherell Kate , Combs Kelly A. , Groden Joanna
Published: September 2005

Recombination-mediated pathways for telomere lengthening may be utilized in the absence of telomerase activity. The RecQ-like helicases, BLM and Sgs1, are implicated in recombination-mediated telomere lengthening in human cells and budding yeast, respectively. Here, we show that BLM expression rescues disrupted telomere lengthening in telomerase-negative sgs1 yeast. BLM helicase activity is required for this complementation, indicating BLM and Sgs1 resolve the same telomeric structures. These data support a conserved function for BLM and Sgs1 in recombination-mediated telomere lengthening.
CD26 Regulates p38 Mitogen-Activated Protein Kinase–Dependent Phosphorylation of Integrin β1, Adhesion to Extracellular Matrix, and Tumorigenicity of T-Anaplastic Large Cell Lymphoma Karpas 299
Authors: Sato Tsutomu , Yamochi Tadanori , Yamochi Toshiko , Aytac Ugur , Ohnuma Kei , McKee Kathryn S. , Morimoto Chikao , Dang Nam H.
Published: September 2005

CD26 is an antigen with key role in T-cell biology and is expressed on selected subsets of aggressive T-cell malignancies. To elucidate the role of CD26 in tumor behavior, we examine the effect of CD26 depletion by small interfering RNA transfection of T-anaplastic large cell lymphoma Karpas 299. We show that the resultant CD26-depleted clones lose the ability to adhere to fibronectin and collagen I. Because anti–integrin β1 blocking antibodies also prevent binding of Karpas 299 to fibronectin and collagen I, we then evaluate the CD26-integrin β1 association. CD26 depletion does not decrease integrin β1 expression but leads to dephosphorylation of both integrin β1 and p38 mitogen-activated protein kinase (MAPK). Moreover, our data showing that the p38MAPK inhibitor SB203580 dephosphorylates integrin β1 and that binding of the anti-CD26 antibody 202.36 dephosphorylates both p38MAPK and integrin β1 on Karpas 299, leading to loss of cell adhesion to the extracellular matrix, indicate that CD26 mediates cell adhesion through p38MAPK-dependent phosphorylation of integrin β1. Finally, in vivo experiments show that depletion of CD26 is associated with loss of tumorigenicity and greater survival. Our findings hence suggest that CD26 plays an important role in tumor development and may be a novel therapeutic target for selected neoplasms.