bluuebunny/crossref_metadata_2025_split huggingface dataset:
MICA Expressed by Multiple Myeloma and Monoclonal Gammopathy of Undetermined Significance Plasma Cells Costimulates Pamidronate-Activated γδ Lymphocytes
Authors: Girlanda Stefania , Fortis Claudio , Belloni Daniela , Ferrero Elisabetta , Ticozzi Paolo , Sciorati Clara , Tresoldi Moreno , Vicari Aurelio , Spies Thomas , Groh Veronika , Caligaris-Cappio Federico , Ferrarini Marina 
Published: September 2005

Abstract
Amino-biphosphonates (like pamidronate) activate human Vγ9/Vδ2 T lymphocytes and promote their cytotoxicity against multiple myeloma cells. T-cell receptor (TCR)–mediated effector functions of γδ cells are enhanced upon triggering of the activating receptor NKG2D by MICA, a stress-inducible antigen expressed by epithelial and some hematopoietic tumors, including multiple myeloma. Here we show that MICA was expressed not only by myeloma cell lines and by 6 of 10 primary multiple myeloma cells from patients but also by bone marrow plasma cells from all (six of six) patients with preneoplastic gammopathy (monoclonal gammopathy of undetermined significance, MGUS), a direct precursor of multiple myeloma. Moreover, compared with multiple myeloma plasma cells, MICA was expressed by MGUS plasma cells at significantly (P &lt; 0.05) higher levels. MICA expressed by myeloma cell lines contributed to killing and IFN-γ production by Vγ9/Vδ2 cells only upon pamidronate treatment, suggesting a dual interaction between Vγ9/Vδ2 lymphocytes and multiple myeloma plasma cells involving both TCR triggering and NKG2D-mediated signals. Finally, MICA enhanced killing of freshly derived, pamidronate-treated multiple myeloma cells from patients by γδ cells, as indicated by the significantly (P &lt; 0.05) higher γδ cytotoxicity against MICA-positive rather than MICA-negative multiple myeloma cells. Our results indicate that MICA expressed by monoclonal plasma cells is functional and correlates with disease stages, suggesting a role for the molecule in the immune surveillance against multiple myeloma. Moreover, pamidronate-activated Vγ9/Vδ2 lymphocytes can be exploited in the immune therapy of early stages multiple myeloma and possibly of premalignant disease.
Endogenous Osteonectin/SPARC/BM-40 Expression Inhibits MDA-MB-231 Breast Cancer Cell Metastasis
Authors: Koblinski Jennifer E. , Kaplan-Singer Benjamin R. , VanOsdol Sherilyn J. , Wu Michael , Engbring Jean A. , Wang Songlin , Goldsmith Corinne M. , Piper John T. , Vostal Jaroslav G. , Harms John F. , Welch Danny R. , Kleinman Hynda K. 
Published: September 2005

Abstract
Skeletal metastases occur with high incidence in patients with breast cancer and cause long-term skeletal morbidity. Osteonectin (SPARC, BM-40) is a bone matrix factor that is an in vitro chemoattractant for breast and prostate cancer cells. Increased expression of osteonectin is found in malignant breast tumors. We infected MDA-231 breast cancer cells with an adenovirus expressing osteonectin to examine the role of osteonectin expression in breast cancer cells and its effect on metastasis, in particular to bone. Expression of osteonectin did not affect MDA-231 cell proliferation, apoptosis, migration, cell aggregation, or protease cleavage of collagen IV. However, in vitro invasion of these osteonectin-infected cells through Matrigel and colony formation on Matrigel was decreased. Interestingly, high osteonectin expression in MDA-231 cells inhibited metastasis in a dose-dependent manner to many different organs including bone. The reduction in metastasis may be due to decreased platelet-tumor cell aggregation, because exogenous osteonectin inhibited platelet aggregation in vitro and the high osteonectin expression in MDA-231 cells reduced tumor cell-induced thrombocytopenia in vivo compared with control-infected cells. These studies suggest that high endogenous expression of osteonectin in breast cancer cells may reduce metastasis via reduced invasive activity and reduced tumor cell-platelet aggregation.
Activation of Akt and eIF4E Survival Pathways by Rapamycin-Mediated Mammalian Target of Rapamycin Inhibition
Authors: Sun Shi-Yong , Rosenberg Laura M. , Wang Xuerong , Zhou Zhongmei , Yue Ping , Fu Haian , Khuri Fadlo R. 
Published: September 2005

Abstract
The mammalian target of rapamycin (mTOR) has emerged as an important cancer therapeutic target. Rapamycin and its derivatives that specifically inhibit mTOR are now being actively evaluated in clinical trials. Recently, the inhibition of mTOR has been shown to reverse Akt-dependent prostate intraepithelial neoplasia. However, many cancer cells are resistant to rapamycin and its derivatives. The mechanism of this resistance remains a subject of major therapeutic significance. Here we report that the inhibition of mTOR by rapamycin triggers the activation of two survival signaling pathways that may contribute to drug resistance. Treatment of human lung cancer cells with rapamycin suppressed the phosphorylation of p70S6 kinase and 4E-BP1, indicating an inhibition of mTOR signaling. Paradoxically, rapamycin also concurrently increased the phosphorylation of both Akt and eIF4E. The rapamycin-induced phosphorylation of Akt and eIF4E was suppressed by the phosphatidylinositol-3 kinase (PI3K) inhibitor LY294002, suggesting the requirement of PI3K in this process. The activated Akt and eIF4E seem to attenuate rapamycin's growth-inhibitory effects, serving as a negative feedback mechanism. In support of this model, rapamycin combined with LY294002 exhibited enhanced inhibitory effects on the growth and colony formation of cancer cells. Thus, our study provides a mechanistic basis for enhancing mTOR-targeted cancer therapy by combining an mTOR inhibitor with a PI3K or Akt inhibitor.
Perifosine Inhibits Multiple Signaling Pathways in Glial Progenitors and Cooperates With Temozolomide to Arrest Cell Proliferation in Gliomas In vivo
Authors: Momota Hiroyuki , Nerio Edward , Holland Eric C. 
Published: September 2005

Abstract
Perifosine is an oral Akt inhibitor which exerts a marked cytotoxic effect on human tumor cell lines, and is currently being tested in several phase II trials for treatment of major human cancers. However, the efficacy of perifosine in human gliomas has not been established. As Akt is activated in ∼70% of human glioblastomas, we investigated the impact of perifosine on glia in culture and on a mouse glioma model in vivo. Here we show that perifosine strongly reduces phosphorylation levels of Akt and extracellular signal-regulated kinase (Erk) 1/2, induces cell cycle arrest in G1 and G2, and causes dose-dependent growth inhibition of mouse glial progenitors in which Akt and/or Ras-Erk 1/2 pathways are activated. Furthermore, because temozolomide is a common oral alkylating agent used in the treatment of gliomas, we investigated the effect of perifosine in combination with temozolomide. We observed an enhanced effect when both were used in culture. With these results, we combined perifosine and temozolomide as treatment of platelet-derived growth factor B–driven gliomas in mice. Animal studies showed that perifosine and temozolomide combination therapy was more effective than temozolomide treatment alone (P &lt; 0.01). These results indicate that perifosine is an effective drug in gliomas in which Akt and Ras-Erk 1/2 pathways are frequently activated, and may be a new candidate for glioma treatment in the clinic.
Restarting the Cell Cycle When the Checkpoint Comes to a Halt
Authors: van Vugt Marcel A.T.M. , Bràs Alexandra , Medema René H. 
Published: September 2005

Abstract
The DNA damage checkpoint coordinates a block in cell proliferation with the DNA repair process that follows when lesions are inflicted on the genome. However, we do not know exactly how cell division can recommence following a DNA damage–induced arrest. Recent work from our lab has identified Polo-like kinase-1 and Cdc25B as two essential components of the machinery that sets the cell division process back in motion when the checkpoint response is abrogated. Here, we discuss these novel insights and discuss their possible implications for the treatment of cancer.
Mect1-Maml2 Fusion Oncogene Linked to the Aberrant Activation of Cyclic AMP/CREB Regulated Genes
Authors: Coxon Amy , Rozenblum Ester , Park Yoon-Soo , Joshi Nina , Tsurutani Junji , Dennis Phillip A. , Kirsch Ilan R. , Kaye Frederic J. 
Published: September 2005

Abstract
Malignant salivary gland tumors can arise from a t(11;19) translocation that fuses 42 residues from Mect1/Torc1, a cyclic AMP (cAMP)/cAMP-responsive element binding protein (CREB)–dependent transcriptional coactivator, with 982 residues from Maml2, a NOTCH receptor coactivator. To determine if the Mect1-Maml2 fusion oncogene mediates tumorigenicity by disrupting cAMP/CREB signaling, we have generated in-frame deletions within the CREB-binding domain of Mect1/Torc1 for testing transformation activity and have also developed a doxycycline-regulated Mect1-Maml2 mammalian expression vector for global gene expression profiling. We observed that small deletions within the CREB-binding domain completely abolished transforming activity in RK3E epithelial cells. Further, we have shown that the ectopic induction of Mect1-Maml2 in HeLa cells strongly activated the expression of a group of known cAMP/CREB-regulated genes. In addition, we detected candidate cAMP-responsive element sites within 100 nucleotides of the transcriptional start sites of other genes activated by Mect1-Maml2 expression. In contrast, we did not observe alterations of known Notch-regulated target genes in these expression array profile experiments. We validated the results by reverse transcription-PCR in transfected HeLa, RK3E, and H2009 lung tumor cells and in mucoepidermoid cancer cells that endogenously express the fusion oncopeptide. Whereas overexpression of components of the cAMP pathway has been associated with a subset of human carcinomas, these data provide a direct genetic link between deregulation of cAMP/CREB pathways and epithelial tumorigenesis and suggest future therapeutic strategies for this group of salivary gland tumors.
Endothelin Axis Is a Target of the Lung Metastasis Suppressor Gene RhoGDI2
Authors: Titus Brian , Frierson Henry F. , Conaway Mark , Ching Keith , Guise Theresa , Chirgwin John , Hampton Garret , Theodorescu Dan 
Published: September 2005

Abstract
Half of patients treated for locally advanced bladder cancer relapse with often fatal metastatic disease to the lung. We have recently shown that reduced expression of the GDP dissociation inhibitor, RhoGDI2, is associated with decreased survival of patients with advanced bladder cancer. However, the effectors by which RhoGDI2 affects metastasis are unknown. Here we use DNA microarrays to identify genes suppressed by RhoGDI2 reconstitution in lung metastatic bladder cancer cell lines. We identify such RNAs and focus only on those that also increase with tumor stage in human bladder cancer samples to discover only clinically relevant targets of RhoGDI2. Levels of endothelin-1 (ET-1), a potent vasoconstrictor, were affected by both RhoGDI2 reconstitution and tumor stage. To test the hypothesis that the endothelin axis is important in lung metastasis, lung metastatic bladder carcinoma cells were injected in mice treated with the endothelin receptor–specific antagonist, atrasentan, thereby blocking engagement of the up-regulated ET-1 ligand with its cognate receptor. Endothelin antagonism resulted in a dramatic reduction of lung metastases, similar to the effect of reexpressing RhoGDI2 in these metastatic cells. Taken together, these experiments show a novel approach of identifying therapeutic targets downstream of metastasis suppressor genes. The data also suggest that blockade of the ET-1 axis may prevent lung metastasis, a new therapeutic concept that warrants clinical evaluation.
Frequent Inactivation of PTEN by Promoter Hypermethylation in Microsatellite Instability-High Sporadic Colorectal Cancers
Authors: Goel Ajay , Arnold Christian N. , Niedzwiecki Donna , Carethers John M. , Dowell Jeannette M. , Wasserman Linda , Compton Carolyn , Mayer Robert J. , Bertagnolli Monica M. , Boland C. Richard 
Published: September 2005

Abstract
Loss of PTEN tumor suppressor function is observed in tumors of breast, prostate, thyroid, and endometrial origin. Allelic losses in the proximity of the PTEN locus (10q23) also occur in sporadic colorectal cancers (CRCs), but biallelic inactivation of this site has not been frequently demonstrated. We hypothesized that alternative mechanisms of PTEN allelic inactivation, such as promoter hypermethylation, might be operative in CRC and that PTEN inactivation may be related to recognized forms of genomic instability. We characterized a cohort of 273 sporadic CRCs by determining their microsatellite instability (MSI) status. Of these, 146 cancers were examined for PTEN promoter methylation by methylation-specific PCR. Mutations at the poly(A)6 repeat sequences in PTEN exons 7 and 8 and deletions at the 10q23 locus were also identified using microsatellite analysis. The presence of PTEN protein was determined by immunostaining, and the results were correlated with the promoter methylation status. We observed that PTEN promoter hypermethylation was a frequent occurrence in MSI-high (MSI-H) tumors (19.1% of MSI-H versus 2.2% of MSI-low/microsatellite stable tumors; P = 0.002). A PTEN mutation or a deletion event was present in 60% of the tumors with promoter region hypermethylation. Hypermethylation of the PTEN promoter correlated significantly with either decreased or complete loss of PTEN protein expression (P = 0.004). This is the first demonstration of PTEN inactivation as a result of promoter hypermethylation in MSI-H sporadic CRCs. These data suggest that this silencing mechanism plays a major role in PTEN inactivation and, in colon cancer, may be more important than either allelic losses or inactivating mutations. The significant correlation of PTEN hypermethylation with MSI-H tumors further suggests that PTEN is an additional important “target” of methylation along with the hMLH1 gene in the evolution of MSI-H CRCs and also confers the “second hit” in the biallelic inactivation mechanism for some proportion of tumors.
Emodin Enhances Arsenic Trioxide-Induced Apoptosis via Generation of Reactive Oxygen Species and Inhibition of Survival Signaling
Authors: Yi Jing , Yang Jie , He Rong , Gao Fei , Sang Hairong , Tang Xueming , Ye Richard D. 
Published: September 2005

Abstract
Although arsenic trioxide (As2O3) induces apoptosis in a relatively wide spectrum of tumors, the sensitivity of different cell types to this treatment varies to a great extent. Because reactive oxygen species (ROS) are critically involved in As2O3-induced apoptosis, we attempted to explore the possibility that elevating the cellular ROS level might be an approach to facilitate As2O3-induced apoptosis. Emodin, a natural anthraquinone derivative, was selected because its semiquinone structure is likely to increase the generation of intracellular ROS. Its independent and synergistic effects with As2O3 in cytotoxicity were studied, and the plausible signaling mechanism was investigated in HeLa cells. Cell Proliferation Assay and flow cytometry were used to assess cell viability and apoptosis. Electrophoretic mobility shift assay, luciferase reporter assay, and Western blotting were performed to analyze signaling alteration. The results demonstrated that coadministration of emodin, at low doses of 0.5–10 μm, with As2O3 enhanced As2O3-rendered cytotoxicity on tumor cells, whereas these treatments caused no detectable proproliferative or proapoptotic effects on nontumor cells. ROS generation was increased, and activation of nuclear factor κB and activator protein 1 was suppressed by coadministration. All enhancements by emodin could be abolished by the antioxidant N-acetyl-l-cysteine. Therefore, we concluded that emodin sensitized HeLa cells to As2O3 via generation of ROS and ROS-mediated inhibition on two major prosurvival transcription factors, nuclear factor κB and activator protein 1. This result allows us to propose a novel strategy in chemotherapy that uses mild ROS generators to facilitate apoptosis-inducing drugs whose efficacy depends on ROS.
Regional Effects of an Antivascular Endothelial Growth Factor Receptor Monoclonal Antibody on Receptor Phosphorylation and Apoptosis in Human 253J B-V Bladder Cancer Xenografts
Authors: Davis Darren W. , Inoue Keiji , Dinney Colin P. N. , Hicklin Daniel J. , Abbruzzese James L. , McConkey David J. 
Published: September 2005

Abstract
Vascular endothelial growth factor (VEGF) is a key angiogenic factor in a variety of solid tumors, making it one of the most attractive therapeutic targets. VEGF promotes the proliferation, survival, and differentiation of vascular endothelial cells by stimulating autophosphorylation and activation of VEGF receptor-2 (VEGFR-2, fetal liver kinase-1, and kinase insert domain-containing receptor). We developed fluorescence-based, quantitative methods to measure total VEGFR-2, VEGFR-2 phosphorylation, apoptosis, and microvessel density and size within whole tumor cross-sections using a laser scanning cytometer. Using these methods, we characterized the effects of DC101, a blocking antibody specific for murine VEGFR-2, on orthotopic human 253J-BV bladder tumors growing in nude mice. Basal levels of receptor phosphorylation were heterogeneous, with approximately 50% of endothelial cells positive for phosphorylated VEGFR-2 at baseline. DC101 therapy resulted in a 50% decrease in overall VEGFR-2 phosphorylation and a 15-fold and 8-fold increase in endothelial cell (CD31-positive) and tumor cell apoptosis, respectively. DC101 also decreased overall tumor microvessel density, but it mostly affected smaller CD105-negative microvessels located in the periphery of the tumor. Intriguingly, anti-VEGFR-2 therapy resulted in increased mean vessel size and an increase in overall VEGFR-2 levels. Increases in total VEGFR-2 levels were localized to the tumor core and were associated with increased expression of the oxygen-sensitive transcription factor, hypoxia inducible factor-1α. These data suggest that VEGFR inhibitors preferentially target discrete populations of tumor endothelial cells associated with the smaller peripheral blood vessels. Thus, agents that target a single receptor (e.g., VEGFR-2) may not be sufficient to completely inhibit tumor angiogenesis.
Lineage Infidelity of MDA-MB-435 Cells
Authors: Sellappan Shankar , Grijalva Rebecca , Zhou Xiaoyan , Yang Wentao , Eli Menashe Bar , Mills Gordon B. , Yu Dihua 
Published: September 2005

Abstract
The origin of cell lines is critical in defining cell type-specific biological functions. Several reports (D. T. Ross et al., Nat Genet 2000;24:227–35; G. Ellison et al., J Clin Pathol Mol Pathol 2002;55:294–9) suggested that the MDA-MB-435 cell line, a cell line extensively used for studying breast cancer biology, has a gene expression pattern most compatible with melanocyte origin. However, we demonstrate that MDA-MB-435 cells express breast-specific or epithelial-specific markers. Also, MDA-MB-435 cells were induced to express breast differentiation-specific proteins and secrete milk lipids as observed in other well-established breast cancer cell lines. Notably, MDA-MB-435 cells also expressed melanocyte-specific proteins as did another highly aggressive breast cancer cell line. MDA-MB-435 xenograft tissue sections stained entirely positive for epithelium-specific markers but only partially positive for melanocyte-specific markers. Thus, MDA-MB-435 is most likely a breast epithelial cell line that has undergone lineage infidelity.
Expression and Activation of Signal Regulatory Protein α on Astrocytomas
Authors: Chen Thomas T. , Brown Eric J. , Huang Eric J. , Seaman William E. 
Published: September 2005

AbstractHigh-grade astrocytomas and glioblastomas are usually unresectable because they extensively invade surrounding brain tissue. Here, we report the expression and function of a receptor on many astrocytomas that may alter both the proliferative and invasive potential of these tumors. Signal regulatory protein (SIRP) α1 is an immunoglobulin superfamily transmembrane glycoprotein that is normally expressed in subsets of myeloid and neuronal cells. Transfection of many cell types with SIRPα1, including glioblastomas, has been shown to inhibit their proliferation in response to a range of growth factors. Furthermore, the expression of a murine SIRPα1 mutant has been shown to enhance cell adhesion and initial cell spreading but to inhibit cell extension and movement. The extracellular portion of SIRPα1 binds CD47 (integrin-associated protein), although this interaction is not required for integrin-mediated activation of SIRPα1. On phosphorylation, SIRPα1 recruits the tyrosine phosphatases SHP-1 and SHP-2, which are important in its functions. Although SHP-1 is uniquely expressed on hematopoietic cells, SHP-2 is ubiquitously expressed, so that SIRPα1 has the potential to function in many cell types, including astrocytomas. Because SIRPα1 regulates cell functions that may contribute to the malignancy of these tumors, we examined the expression of SIRPs in astrocytoma cell lines by flow cytometry using a monoclonal antibody against all SIRPs. Screening of nine cell lines revealed clear cell surface expression of SIRPs on five cell lines, whereas Northern blotting for SIRPα transcripts showed mRNA present in eight of nine cell lines. All nine cell lines expressed the ligand for SIRPα1, CD47. To further examine the expression and function of SIRPs, we studied the SF126 and U373MG astrocytoma cell lines, both of which express SIRPs, in greater detail. SIRP transcripts in these cells are identical in sequence to SIRPα1. The expressed deglycosylated protein is the same size as SIRPα1, but in the astrocytoma cells, it is underglycosylated compared with SIRPα1 produced in transfected Chinese hamster ovary cells. It is nonetheless still capable of binding soluble CD47. Moreover, SIRPα1 in each of the two cell lines recruited SHP-2 on phosphorylation, and SIRPα1 phosphorylation in cultured cells is CD47 dependent. Finally, examination of frozen sections from 10 primary brain tumor biopsies by immunohistochemistry revealed expression of SIRPs on seven of the specimens, some of which expressed high levels of SIRPs. Most of the tumors also expressed CD47. This is the first demonstration that astrocytomas can express SIRPα. Given the known role of SIRPα in regulating cell adhesion and responses to mitogenic growth factors, the expression of SIRPα1 on astrocytomas may be of considerable importance in brain tumor biology, and it offers the potential of a new avenue for therapeutic intervention.