bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biofilm Formation by
Pneumocystis
spp
Authors: Cushion Melanie T. , Collins Margaret S. , Linke Michael J. 
Published: September 2008

ABSTRACT

Pneumocystis
spp. can cause a lethal pneumonia in hosts with debilitated immune systems. The manner in which these fungal infections spread throughout the lung, the life cycles of the organisms, and their strategies used for survival within the mammalian host are largely unknown, due in part to the lack of a continuous cultivation method. Biofilm formation is one strategy used by microbes for protection against environmental assaults, for communication and differentiation, and as foci for dissemination. We posited that the attachment and growth of
Pneumocystis
within the lung alveoli is akin to biofilm formation. An in vitro system comprised of insert wells suspended in multiwell plates containing supplemented RPMI 1640 medium supported biofilm formation by
P. carinii
(from rat) and
P. murina
(from mouse).Dramatic morphological changes accompanied the transition to a biofilm. Cyst and trophic forms became highly refractile and produced branching formations that anastomosed into large macroscopic clusters that spread across the insert. Confocal microscopy revealed stacking of viable organisms enmeshed in concanavalin A-staining extracellular matrix. Biofilms matured over a 3-week time period and could be passaged. These passaged organisms were able to cause infection in immunosuppressed rodents. Biofilm formation was inhibited by farnesol, a quorum-sensing molecule in
Candida
spp., suggesting that a similar communication system may be operational in the
Pneumocystis
biofilms. Intense staining with a monoclonal antibody to the major surface glycoproteins and an increase in (1,3)-β-
d
-glucan content suggest that these components contributed to the refractile properties. Identification of this biofilm process provides a tractable in vitro system that should fundamentally advance the study of
Pneumocystis
.
Abnormal DNA Methylation ofCD133in Colorectal and Glioblastoma Tumors
Authors: Yi Joo Mi , Tsai Hsing-Chen , Glöckner Sabine C. , Lin Steven , Ohm Joyce E. , Easwaran Hari , James C. David , Costello Joseph F. , Riggins Gregory , Eberhart Charles G. , Laterra John , Vescovi Angelo L. , Ahuja Nita , Herman James G. , Schuebel Kornel E. , Baylin Stephen B. 
Published: October 2008

AbstractMuch recent effort has focused on identifying and characterizing cellular markers that distinguish tumor propagating cells (TPC) from more differentiated progeny. We report here an unusual promoter DNA methylation pattern for one such marker, the cell surface antigen CD133 (Prominin 1). This protein has been extensively used to enrich putative cancer propagating stem-like cell populations in epithelial tumors and, especially, glioblastomas. We find that, within individual cell lines of cultured colon cancers and glioblastomas, the promoter CpG island of CD133 is DNA methylated, primarily, in cells with absent or low expression of the marker protein, whereas lack of such methylation is evident in purely CD133+ cells. Differential histone modification marks of active versus repressed genes accompany these DNA methylation changes. This heterogeneous CpG island DNA methylation status in the tumors is unusual in that other DNA hypermethylated genes tested in such cultures preserve their methylation patterns between separated CD133+ and CD133− cell populations. Furthermore, the CD133 DNA methylation seems to constitute an abnormal promoter signature because it is not found in normal brain and colon but only in cultured and primary tumors. Thus, the DNA methylation is imposed on the transition between the active versus repressed transcription state for CD133 only in tumors. Our findings provide additional insight for the dynamics of aberrant DNA methylation associated with aberrant gene silencing in human tumors. [Cancer Res 2008;68(19):8094–103]
Ectopic Expression of P-Cadherin Correlates with Promoter Hypomethylation Early in Colorectal Carcinogenesis and Enhanced Intestinal Crypt Fission In vivo
Authors: Milicic Anita , Harrison Lea-Anne , Goodlad Robert A. , Hardy Robert G. , Nicholson Anna M. , Presz Michal , Sieber Oliver , Santander Sonia , Pringle James H. , Mandir Nikki , East Philip , Obszynska Jolanta , Sanders Scott , Piazuelo Elena , Shaw Jacqui , Harrison Rebecca , Tomlinson Ian P. , McDonald Stuart A.C. , Wright Nicholas A. , Jankowski Janusz A.Z. 
Published: October 2008

Abstract
P-cadherin is normally expressed in the basal layer of squamous epithelia and absent from the healthy intestine and colon. We have previously shown it to be expressed in all inflamed, hyperplastic, and dysplastic intestinal and colonic mucosa. This study aimed to better understand the mechanisms controlling the expression of P-cadherin and the biological effects of its ectopic presence in the intestine and colon. We investigated the CpG methylation status of the P-cadherin (CDH3) promoter and P-cadherin mRNA and protein expression in cases of familial and sporadic colorectal cancer (CRC). The CDH3 promoter was hypomethylated in colonic aberrant crypt foci, in CRC, and, occasionally, in the normal epithelium adjacent to cancer, demonstrating a potential “field effect” of cancerization. The hypomethylation was also associated with induction of P-cadherin expression in the neoplastic colon (P &lt; 0.0001). We then created transgenic mice that overexpressed P-cadherin specifically in the intestinal and colonic epithelium under the liver fatty acid binding protein promoter. Forced ectopic expression of P-cadherin accompanied by indomethacin-induced inflammation resulted in a 3-fold higher crypt fission rate within the small and large intestines in the homozygous mice compared with the wild-type animals (P &lt; 0.02). We conclude that epigenetic demethylation of the P-cadherin promoter in the human intestine permits its ectopic expression very early in the colorectal adenoma-carcinoma sequence and persists during invasive cancer. Induced P-cadherin expression, especially in mucosal damage, leads to an increased rate of crypt fission, a common feature of clonal expansion in gastrointestinal dysplasia. [Cancer Res 2008;68(19):7760–8]
Heterogeneity of Receptor Function in Colon Carcinoma Cells Determined by Cross-talk between Type I Insulin-like Growth Factor Receptor and Epidermal Growth Factor Receptor
Authors: Hu Yi Peter , Patil Sandip B. , Panasiewicz Michelle , Li Wenhui , Hauser Jennie , Humphrey Lisa E. , Brattain Michael G. 
Published: October 2008

Abstract
This study identifies a novel cross-talk paradigm between the type I insulin-like growth factor receptor (IGF1R) and epidermal growth factor receptor (EGFR) in colon cancer cells. IGF1R activation by ligand exposure in growth factor–deprived cells induces Akt activation in the FET, CBS, and GEO colon cancer cell lines. Investigation of IGF1R-mediated signaling pathways using small interfering RNA approaches indicated that, as expected, phosphatidylinositol 3′-kinase (PI3K) was activated by IGF1R. Mitogen-activated protein kinase (MAPK) activity as reflected by phospho-extracellular signal-regulated kinase (ERK) induction was not significantly activated until later times following release of these cells from growth factor deprivation stress. The appearance of phospho-ERK was proximal to EGFR activation. Treatment of cells with the PI3K inhibitor LY294002 before release from stress resulted in a concentration-dependent loss of EGFR activation, whereas treatment with the MAPK inhibitor PD98059 did not block EGFR activation, indicating that EGFR activation was downstream of the IGF1R/PI3K pathway. PD98059 inhibition of MAPK was associated with a concentration-dependent reduction in EGFR-mediated phospho-ERK. EGFR inhibitor blocked induction of phospho-ERK, showing that MAPK activity was a consequence of EGFR-mediated signaling. On the other hand, a small-molecule IGF1R inhibitor, PQIP, blocked Akt phosphorylation. The divergent signaling functions of IGF1R and EGFR suggested the potential for synergism by a combination of therapy directed at the two receptors. Combination treatment with PQIP and EGFR inhibitor Tarceva resulted in synergistic effects as indicated by combination index analysis in all three cell lines tested. [Cancer Res 2008;68(19):8004–13]
Tbx3 Represses E-Cadherin Expression and Enhances Melanoma Invasiveness
Authors: Rodriguez Mercedes , Aladowicz Ewa , Lanfrancone Luisa , Goding Colin R. 
Published: October 2008

Abstract
The T-box transcription factors Tbx2 and Tbx3 are overexpressed in many cancers and in melanoma promote proliferation by actively suppressing senescence. Whether they also contribute to tumor progression via other mechanisms is not known. Here, we identify a novel role for these factors, providing evidence that Tbx3, and potentially Tbx2, directly repress the expression of E-cadherin, a keratinocyte-melanoma adhesion molecule whose loss is required for the acquisition of an invasive phenotype. Overexpression of Tbx2 and Tbx3 in melanoma cells down-regulates endogenous E-cadherin expression, whereas depletion of Tbx3, but not Tbx2, increases E-cadherin mRNA and protein levels and decreases melanoma invasiveness in vitro. Consistent with these observations, in melanoma tissue, Tbx3 and E-cadherin expression are inversely correlated. Depletion of Tbx3 also leads to substantial up-regulation of Tbx2. The results suggest that Tbx2 and Tbx3 may play a dual role during the radial to vertical growth phase transition by both inhibiting senescence via repression of p21CIP1 expression, and enhancing melanoma invasiveness by decreasing E-cadherin levels. [Cancer Res 2008;68(19):7872–81]
Evaluation of Cancer Tests of 1,3-Butadiene Using Internal Dose, Genotoxic Potency, and a Multiplicative Risk Model
Authors: Fred Charlotta , Törnqvist Margareta , Granath Fredrik 
Published: October 2008

Abstract
In cancer tests with 1,3-butadiene (BD), the mouse is much more sensitive than the rat. This is considered to be related to the metabolism of BD to the epoxide metabolites, 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane, and 1,2-epoxy-3,4-butanediol. This study evaluates whether the large difference in outcome in cancer tests with BD could be predicted quantitatively on the basis of the concentration over time in blood (AUC) of the epoxide metabolites, their mutagenic potency, and a multiplicative cancer risk model, which has earlier been used for ionizing radiation. Published data on hemoglobin adduct levels from inhalation experiments with BD were used for the estimation of the AUC of the epoxide metabolites in the cancer tests. The estimated AUC of the epoxides were then weighed together to a total genotoxic dose, by using the relative genotoxic potency of the respective epoxide inferred from in vitro hprt mutation assays using EB as standard. The tumor incidences predicted with the risk model on the basis of the total genotoxic dose correlated well with the earlier observed tumor incidences in the cancer tests. The total genotoxic dose that leads to a doubling of the tumor incidences was estimated to be the same in both species, 9 to 10 mmol/L×h EB-equivalents. The study validates the applicability of the multiplicative cancer risk model to genotoxic chemicals. Furthermore, according to this evaluation, different epoxide metabolites are predominating cancer-initiating agents in the cancer tests with BD, the diepoxide in the mouse, and the monoepoxides in the rat. [Cancer Res 2008;68(19):8014–21]
CD8+ T-Cell Responses against Hemoglobin-β Prevent Solid Tumor Growth
Authors: Komita Hideo , Zhao Xi , Taylor Jennifer L. , Sparvero Louis J. , Amoscato Andrew A. , Alber Sean , Watkins Simon C. , Pardee Angela D. , Wesa Amy K. , Storkus Walter J. 
Published: October 2008

AbstractBone marrow–derived dendritic cells engineered using recombinant adenovirus to secrete high levels of IL-12p70 dramatically inhibited the growth of established CMS4 sarcomas in BALB/c mice after intratumoral administration. An analysis of splenic CD8+ T cells in regressor mice revealed a strong, complex reactivity pattern against high-performance liquid chromatography (HPLC)–resolved peptides isolated by acid elution from single-cell suspensions of surgically resected CMS4 lesions. Mass spectrometry analyses defined two major overlapping peptide species that derive from the murine hemoglobin-β (HBB) protein within the most stimulatory HPLC fractions. Although cultured CMS4 tumor cells failed to express HBB mRNA based on reverse transcription-PCR analyses, prophylactic vaccination of BALB/c mice with vaccines containing HBB peptides promoted specific CD8+ T-cell responses that protected mice against a subsequent challenge with CMS4 or unrelated syngeneic (HBBneg) tumors of divergent histology (sarcoma, carcinomas of the breast or colon). In situ imaging suggested that vaccines limit or destabilize tumor-associated vascular structures, potentially by promoting immunity against HBB+ vascular pericytes. Importantly, there were no untoward effects of vaccination with the HBB peptide on peripheral RBC numbers, RBC hemoglobin content, or vascular structures in the brain or eye. [Cancer Res 2008;68(19):8076–84]
Chromosomal Instability in Unirradiated Hemaopoietic Cells Induced by Macrophages Exposed In vivo to Ionizing Radiation
Authors: Lorimore Sally A. , Chrystal Jennifer A. , Robinson Joanne I. , Coates Philip J. , Wright Eric G. 
Published: October 2008

Abstract
The tumorigenic potential of ionizing radiation has conventionally been attributed to DNA damage in irradiated cells induced at the time of exposure. Recently, there have been an increasing number of reports of damage in unirradiated cells that are either neighbors or descendants of irradiated cells, respectively, regarded as bystander effects and genomic instability and collectively termed nontargeted effects. In this study, we show that descendants of normal murine hemaopoietic clonogenic stem cells exposed to bone marrow–conditioned medium derived from γ-irradiated mice exhibit chromosomal instability unlike the descendants of directly γ-irradiated cells. The instability is expressed in bone marrow cells of the radiation-induced acute myeloid leukemia (r-AML) susceptible strain (CBA/Ca) but not in mice resistant to r-AML (C57BL/6). Furthermore, crossgenetic experiments show the induction of the instability phenotype requires both the producer and responder cells to be of the susceptible CBA/Ca genotype. Macrophages are the source of the bystander signals, and the signaling mechanism involves tumor necrosis factor-α, nitric oxide, and superoxide. The findings show a genotype-dependent chromosomal instability phenotype induced by radiation-induced macrophage-mediated bystander signaling. As the majority of accidental, occupational, and therapeutic exposures to ionizing radiation are partial body exposures, the findings have implications for understanding the consequences of such exposure. [Cancer Res 2008;68(19):8122–6]
PIK3CA Cooperates with Other Phosphatidylinositol 3′-Kinase Pathway Mutations to Effect Oncogenic Transformation
Authors: Oda Katsutoshi , Okada Jennifer , Timmerman Luika , Rodriguez-Viciana Pablo , Stokoe David , Shoji Keiko , Taketani Yuji , Kuramoto Hiroyuki , Knight Zachary A. , Shokat Kevan M. , McCormick Frank 
Published: October 2008

Abstract
Mutations in genes functioning in different pathways frequently occur together in the same cancer, whereas mutations in the same pathway tend to be mutually exclusive. However, the majority of colon, breast, and endometrial cancers that possess mutations in PIK3CA, the catalytic subunit p110α of phosphatidylinositol 3′-kinase (PI3K), also possess mutations or alterations in genes upstream of PI3K such as Ras, ERBB2/ERBB3, or PTEN. PIK3CA mutations occur almost exclusively in invasive tumors, whereas upstream mutations occur as frequently in early-stage and late-stage tumors, suggesting that PIK3CA mutation is a late-stage event that may augment earlier activation of the PI3K pathway. Consistent with this, we find that levels of p-AKT (Ser473) induced by mutant Ras or knockdown of PTEN were dramatically increased by addition of mutant PIK3CA. Soft agar assays revealed that anchorage-independent growth induced by mutant Ras was greatly increased in the presence of mutant PIK3CA. In breast, colon, and endometrial cancers in which the PI3K pathway is activated by a combination of mutant PIK3CA and alterations in Ras, ERBB2/3, or PTEN, signaling to downstream elements such as Akt was mediated exclusively by the p110α isoform, rather than a combination of different PI3K isoforms. Our data therefore suggest that in tumors with co-occurring mutations in multiple components of the PI3K pathway, selective inhibition of the α isoform of p110 is an attractive therapeutic strategy, especially for late-stage tumors. [Cancer Res 2008;68(19):8127–36]
Nuclear Survivin Abrogates Multiple Cell Cycle Checkpoints and Enhances Viral Oncolysis
Authors: Connell Claire M. , Wheatley Sally P. , McNeish Iain A. 
Published: October 2008

Abstract
Survivin (BIRC5) promotes cell division and survival with roles as chromosomal passenger protein and inhibitor of apoptosis protein (IAP). It is overexpressed in many cancers and is associated with resistance to chemotherapy and radiation. Previously, we showed that expression of survivin within the nucleus of HeLa cells accelerates its degradation and blocks apoptosis inhibition without affecting localization during mitosis. Here, we have investigated the effects of survivin on cell cycle control and potential therapeutic consequences using HeLa and IGROV1 cells expressing wild-type and nuclear-targeted survivin. We show that overexpression of survivin, especially within the nucleus, increases control over G1-S checkpoint via increased nuclear accumulation of cyclin D and cyclin-dependent kinase 4 and subsequent pRb phosphorylation. We investigated the influence of survivin on the activity of the E1A CR2-deleted oncolytic adenovirus dl922-947, which depends critically on an aberrant G1-S checkpoint. Nuclear expression of survivin augments virus-induced S-phase induction and increases viral protein expression and overall viral replication. There is a consequent increase in antitumor activity both in vitro and in vivo. The increased dl922-947 activity is restricted to malignant cells and is not associated with induction of apoptosis, nor does it rely on the role of survivin as an IAP. In addition, we observe the appearance of a large ≥4N population coincident with multiple mitotic defects in dl922-947–infected cells, both of which are significantly increased by nuclear survivin. This indicates that adenoviral activity is facilitated by abrogation of multiple cell cycle checkpoints and can be enhanced by expression of survivin within the nucleus. [Cancer Res 2008;68(19):7923–31]
Validation of the p21-Activated Kinases as Targets for Inhibition in Neurofibromatosis Type 2
Authors: Yi Chunling , Wilker Erik W. , Yaffe Michael B. , Stemmer-Rachamimov Anat , Kissil Joseph L. 
Published: October 2008

Abstract
Neurofibromatosis type 2 (NF2) is a dominantly inherited cancer disorder caused by mutations at the NF2 gene locus. Merlin, the protein product of the NF2 gene, has been shown to negatively regulate Rac1 signaling by inhibiting its downstream effector kinases, the p21-activated kinases (Pak). Given the implication of Paks in tumorigenesis, it is plausible that merlin's tumor suppressive function might be mediated, at least in part, via inhibition of the Paks. We present data indicating this is indeed the case. First, analysis of primary schwannoma samples derived from NF2 patients showed that in a significant fraction of the tumors, the activity of Pak1 was highly elevated. Second, we used shRNAs to knockdown Pak1, 2, and 3 in NIH3T3 cells expressing a dominant-negative form of merlin, NF2BBA (NIH3T3/NF2BBA), and find that simultaneous knockdown of Pak1-3 in these cells significantly reduced their growth rates in vitro and inhibited their ability to form tumors in vivo. Finally, while attempting to silence Pak1 in rat schwannoma cells, we found that these cells were unable to tolerate long-term Pak1 inhibition and rapidly moved to restore Pak1 levels by shutting down Pak1 shRNA expression through a methylation-dependent mechanism. These data suggest that inhibiting Pak could be a beneficial approach for the development of therapeutics toward NF2. In addition, the finding that the shRNA-mediated Pak1 suppression was silenced rapidly by methylation raises questions about the future application of such technologies for the treatment of diseases such as cancer. [Cancer Res 2008;68(19):7932–7]
Breast Tumor Kinase Phosphorylates p190RhoGAP to Regulate Rho and Ras and Promote Breast Carcinoma Growth, Migration, and Invasion
Authors: Shen Che-Hung , Chen Hsin-Yi , Lin Ming-Shien , Li Fang-Yen , Chang Cheng-Chi , Kuo Min-Liang , Settleman Jeffrey , Chen Ruey-Hwa 
Published: October 2008

Abstract
Breast tumor kinase (Brk), an Src-like nonreceptor tyrosine kinase, is overexpressed in breast cancer and several other cancer types. Our previous study indicates that Brk promotes cell migration and tumor invasion by phosphorylating the focal adhesion protein paxillin. Here, we report the identification of p190RhoGAP-A (p190) as a Brk substrate. Brk phosphorylates p190 at the Y1105 residue both in vitro and in vivo, thereby promoting the association of p190 with p120RasGAP (p120). As a consequence, Brk stimulates p190 and attenuates p120 functions, leading to RhoA inactivation and Ras activation, respectively. In carcinoma cells expressing high levels of Brk, endogenous Brk functions as a key contributor to epidermal growth factor–induced p190 tyrosine phosphorylation. We present evidence showing that p190 phosphorylation plays essential roles in both migratory and proliferative effects of Brk. Furthermore, disruption of p190 phosphorylation–induced p190/p120 complex in breast cancer cells abolishes not only the abilities of Brk to regulate RhoA and Ras but also the stimulatory effects of Brk on proliferation, migration, invasion, transformation, and tumorigenicity. Together, our findings reveal a previously unknown function of Brk in regulating both RhoA and Ras by phosphorylating p190 and provide evidence for the crucial roles of this Brk-elicited signaling pathway in promoting breast malignancy. [Cancer Res 2008;68(19):7779–87]
Runx2 Transcriptional Activation of Indian Hedgehog and a Downstream Bone Metastatic Pathway in Breast Cancer Cells
Authors: Pratap Jitesh , Wixted John J. , Gaur Tripti , Zaidi Sayyed K. , Dobson Jason , Gokul Karthiga Devi , Hussain Sadiq , van Wijnen Andre J. , Stein Janet L. , Stein Gary S. , Lian Jane B. 
Published: October 2008

Abstract
Runx2, required for bone formation, is ectopically expressed in breast cancer cells. To address the mechanism by which Runx2 contributes to the osteolytic disease induced by MDA-MB-231 cells, we investigated the effect of Runx2 on key components of the “vicious cycle” of transforming growth factor β (TGFβ)-mediated tumor growth and osteolysis. We find that Runx2 directly up-regulates Indian Hedgehog (IHH) and colocalizes with Gli2, a Hedgehog signaling molecule. These events further activate parathyroid hormone-related protein (PTHrP). Furthermore, Runx2 directly regulates the TGFβ-induced PTHrP levels. A subnuclear targeting deficient mutant Runx2, which disrupts TGFβ-induced Runx2-Smad interactions, failed to induce IHH and downstream events. In addition, Runx2 knockdown in MDA-MB-231 inhibited IHH and PTHrP expression in the presence of TGFβ. In vivo blockade of the Runx2-IHH pathway in MDA-MB-231 cells by Runx2 short hairpin RNA inhibition prevented the osteolytic disease. Thus, our studies define a novel role of Runx2 in up-regulating the vicious cycle of metastatic bone disease, in addition to Runx2 regulation of genes related to progression of tumor metastasis. [Cancer Res 2008;68(19):7795–802]