bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic and Biochemical Characterization of the
Streptococcus pneumoniae
PcrA Helicase and Its Role in Plasmid Rolling Circle Replication
Authors: Ruiz-Masó J. A. , Anand S. P. , Espinosa M. , Khan S. A. , del Solar G. 
Published: October 2006

ABSTRACT

PcrA is a chromosomally encoded DNA helicase of gram-positive bacteria involved in replication of rolling circle replicating plasmids. Efficient interaction between PcrA and the plasmid-encoded replication initiator (Rep) protein is considered a requirement for the plasmid to replicate in a given host, and thus, the ability of a Rep protein to interact with heterologous PcrA helicases has been invoked as a determinant of plasmid promiscuity. We characterized transcription of the
Streptococcus pneumoniae pcrA
gene in its genetic context and studied the biochemical properties of its product, the PcrA

Spn

helicase. Transcription of the pneumococcal
pcrA
gene was directed by promoter P
a
, consisting of an extended −10 box. Promoter P
a
also accounted for expression of a second essential gene,
radC
, which was transcribed with much lower efficiency than
pcrA
, probably due to the presence of a terminator/attenuator sequence located between the two genes. PcrA

Spn

displayed single-stranded DNA-dependent ATPase activity. PcrA

Spn

showed 5′→3′ and 3′→5′ helicase activities and bound efficiently to partially duplex DNA containing a hairpin structure adjacent to a 6-nucleotide 5′ or 3′ single-stranded tail and one unpaired (flap) nucleotide in the complementary strand. PcrA

Spn

interacted specifically with RepC, the initiator of staphylococcal plasmid pT181. Although the pneumococcal helicase was able to initiate unwinding of the RepC-nicked pT181 DNA, it was much less processive in this activity than the cognate staphylococcal PcrA protein. Accordingly, PcrA

Spn

was inefficient in in vitro replication of pT181, and perhaps as a consequence, this plasmid could not be established in
S. pneumoniae
.
Multiple Interactions between the Transmembrane Division Proteins ofBacillus subtilisand the Role of FtsL Instability in Divisome Assembly
Authors: Daniel Richard A. , Noirot-Gros Marie-Françoise , Noirot Philippe , Errington Jeff 
Published: October 2006

ABSTRACTAbout 11 essential proteins assemble into a ring structure at the surface of the cell to bring about cytokinesis in bacteria. Several of these proteins have their major domains located outside the membrane, forming an assembly that we call the outer ring (OR). Previous work on division inBacillus subtilishas shown that four of the OR proteins—FtsL, DivIC, DivIB, and PBP 2B—are interdependent for assembly. This contrasts with the mainly linear pathway for the equivalent proteins inEscherichia coli. Here we show that the interdependent nature of theB. subtilispathway could be due to effects on FtsL and DivIC stability and that DivIB is an important player in regulating this turnover. Two-hybrid approaches suggest that a multiplicity of protein-protein interactions contribute to the assembly of the OR. DivIC is unusual in interacting strongly only with FtsL. We propose a model for the formation of the OR through the mutual association of the membrane proteins directed by the cytosolic inner-ring proteins.
Abnormalities of chromosome 17 in oesophageal cancer
Authors: Moodley Revendran , Reddi Anunathan , Chetty Runjan , Naidoo Richard 
Published: October 2006

Background:Oesophageal cancer is the most common malignancy encountered in South African males, especially in the Eastern Cape and surrounding region of South Africa. There are a number of risk factors and predisposing conditions that have been implicated in the aetiology of the disease. The tylosis oesophageal cancer (TOC) gene, localised to a small region on chromosome 17q25, has been shown to be associated with oesophageal squamous cell carcinoma.Aim:To investigate loss of heterozygosity (LOH) and microsatellite instability (MSI) in the region of theTOClocus.Methods:In 74 oesophagectomy specimens for squamous cell carcinoma, microsatellite PCR was performed using five fluorescently labelledTOCmarkers. The PCR products were analysed and the data correlated with clinicopathological findings.Results:LOH ranged from 25% to 60%. LOH for the individual markers was as follows: D17S1839, 25%; D17S1864, 36%; D17S1817, 38%; D17S785, 47.8%; and D17S579, 60%. MSI ranged from 4.1% to 6.8% for the five loci in the 17q region. MSI was 4.1% for the markers D17S579, D17S785 and D17S1817. Marker D17S1864 showed MSI to occur in 4 cases (5.4%) and marker D17S1839 in 5 cases (6.8%).Conclusion:No significant relationship between genetic and clinical parameters was observed; however, aberrations in poorly differentiated tumours were high for markers D17S579 and D17S1864 (25% and 37%, respectively), indicating that these markers may have an underlying role in the molecular pathogenesis of oesophageal squamous cell carcinoma. In addition, 63% of patients who died showed LOH for the markers D17S579, D17S1864 and D17S1817.
Serum 25-hydroxyvitamin D levels in early and advanced breast cancer: Table 1
Authors: Palmieri C , MacGregor T , Girgis S , Vigushin D 
Published: October 2006

Background:Laboratory and epidemiological studies have implicated vitamin D deficiency in the pathogenesis of breast cancer. 1,25-Dihydroxyvitamin D (1,25(OH)2D) promotes differentiation and apoptosis, and potently inhibits proliferation of malignant breast epithelial cells in culture. Serum levels of 1,25(OH)2D are higher in normal women than in patients with primary breast cancer.Aim:To clarify the role of vitamin D in breast cancer progression by comparing the levels of serum vitamin D in patients with early and in those with advanced breast cancer.Methods:Circulating levels of 25-hydroxyvitamin D (25(OH)D), parathyroid hormone (PTH) and calcium were measured prospectively in 279 Caucasian women with invasive breast cancer, 204 women with early-stage disease and 75 women with locally advanced or metastatic disease.Results:Patients with early-stage breast cancer had significantly higher circulating levels of 25(OH)D (p<0.005) and significantly lower PTH (p<0.001) levels than those with advanced disease. Calcium levels did not differ significantly (p = 0.74).Conclusion:Serum levels of 25(OH)D are significantly higher in patients with early-stage breast cancer than in those with locally advanced or metastatic disease.
Regulation of Expression of BIK Proapoptotic Protein in Human Breast Cancer Cells: p53-Dependent Induction of BIK mRNA by Fulvestrant and Proteasomal Degradation of BIK Protein
Authors: Hur Jingyung , Bell Daphne W. , Dean Kathleen L. , Coser Kathryn R. , Hilario Pablo C. , Okimoto Ross A. , Tobey Erica M. , Smith Shannon L. , Isselbacher Kurt J. , Shioda Toshi 
Published: October 2006

Abstract
Induction of mRNA for BIK proapoptotic protein by doxorubicin or γ-irradiation requires the DNA-binding transcription factor activity of p53. In MCF7 cells, pure antiestrogen fulvestrant also induces BIK mRNA and apoptosis. Here, we provide evidence that, in contrast to doxorubicin or γ-irradiation, fulvestrant induction of BIK mRNA is not a direct effect of the transcriptional activity of p53, although p53 is necessary for this induction. It is known that p53 up-regulated modulator of apoptosis (PUMA) mRNA is induced directly by the transcriptional activity of p53. Whereas γ-irradiation induced both BIK and PUMA mRNA, only BIK mRNA was induced by fulvestrant. Whereas both fulvestrant and doxorubicin induced BIK mRNA, only doxorubicin enhanced the DNA-binding activity of p53 and induced PUMA mRNA. Small interfering RNA (siRNA) suppression of p53 expression as well as overexpression of dominant-negative p53 effectively inhibited the fulvestrant induction of BIK mRNA, protein, and apoptosis. Transcriptional activity of a 2-kb BIK promoter, which contained an incomplete p53-binding sequence, was not affected by fulvestrant when tested by reporter assay. Fulvestrant neither affected the stability of the BIK mRNA transcripts. Interestingly, other human breast cancer cells, such as ZR75-1, constitutively expressed BIK mRNA even without fulvestrant. In these cells, however, BIK protein seemed to be rapidly degraded by proteasome, and siRNA suppression of BIK in ZR75-1 cells inhibited apoptosis induced by MG132 proteasome inhibitor. These results suggest that expression of BIK in human breast cancer cells is regulated at the mRNA level by a mechanism involving a nontranscriptional activity of p53 and by proteasomal degradation of BIK protein. (Cancer Res 2006; 66(20): 10153-61)
Single-chain Antibodies to the EWS NH2 Terminus Structurally Discriminate between Intact and Chimeric EWS in Ewing's Sarcoma and Interfere with the Transcriptional Activity of EWS In vivo
Authors: Aryee Dave N.T. , Kreppel Michael , Bachmaier Radostina , Üren Aykut , Muehlbacher Karin , Wagner Stefan , Breiteneder Heimo , Ban Jozef , Toretsky Jeffrey A. , Kovar Heinrich 
Published: October 2006

Abstract
The chimeric protein EWS-FLI1, arising from chromosomal translocation in Ewing's sarcoma family tumors (ESFT), acts as an aberrant tumorigenic transcription factor. The transforming activity of EWS-FLI1 minimally requires an ETS DNA binding domain and the EWS NH2 terminus. Proteins interacting with the EWS portion differ between germ-line and chimeric EWS despite their sharing identical sequences in this domain. We explored the use of the phage display technology to isolate anti-EWS-FLI1 specific single-chain antibody fragments (scFvs). Using recombinant EWS-FLI1 as bait, 16 independent specific antibody clones were isolated from combinatorial phage display libraries, of which six were characterized in detail. Despite differing in their complementarity-determining region sequences, all six scFvs bound to the same epitope spanning residues 51 to 75 within the shared minimal transforming EWS domain. Whereas all six scFvs bound efficiently to cellular EWS, reactivity with ESFT-expressed EWS-FLI1 was weak and restricted to denatured protein. One scFv, scFv-I85, when expressed as an intrabody, efficiently suppressed EWS-dependent coactivation of hepatocyte nuclear factor 4– and OCT4-mediated transcription in vivo but no effect on known EWS-FLI1 target genes was observed. These data suggest that a prominent EWS epitope exposed on recombinant EWS-FLI1 structurally differs between germ-line and chimeric EWS in mammalian cells and that this region is functionally involved in the transcriptional activity of EWS. Thus, we have generated a tool that will prove useful to specifically differentiate between normal and rearranged EWS in functional studies. (Cancer Res 2006; 66(20): 9862-9)
Estrogen Receptor-α Phosphorylated at Ser118 Is Present at the Promoters of Estrogen-Regulated Genes and Is Not Altered Due to HER-2 Overexpression
Authors: Weitsman Gregory E. , Li Lin , Skliris George P. , Davie James R. , Ung Kanyarat , Niu Yulian , Curtis-Snell Linda , Tomes Ladislav , Watson Peter H. , Murphy Leigh C. 
Published: October 2006

Abstract
Detection of estrogen receptor (ER)-α phosphorylated at Ser118 (P-Ser118-ER-α) may be an indicator of an intact ligand-dependent ER-α in breast tumors in vivo and may predict responsiveness to endocrine therapy. The current study addresses whether P-Ser118-ER-α is functionally involved in ER target gene transcription and if this is modulated by HER-2 overexpression. Using chromatin immunoprecipitation analysis, P-Ser118-ER-α was found associated with the promoters of several estrogen-regulated genes in MCF-7 breast cancer cells 30 minutes following estrogen treatment. Coactivators AIB1 and p300 were coimmunoprecipitated with P-Ser118-ER-α following estrogen treatment. The overexpression of HER-2 protein in MCF-7 cells did not affect estrogen induction of phosphorylation of Ser118 or its presence at the promoters of several estrogen-regulated genes. U0126, an inhibitor of mitogen-activated protein kinase (MAPK) pathway, had no effect on P-Ser118-ER-α. The lack of effect of HER-2 overexpression on P-Ser118-ER-α expression in cell models is supported by similar levels of expression of P-Ser118-ER-α in ER+/HER-2-overexpressing and ER+/HER-2− breast tumors in vivo. Using inhibitors of cyclin-dependent kinase 7 (Cdk7), [(5,6-dichloro-1-β-d-ribofuranosylbenzimidazole and 2-(R)-1-ethyl-2-hydroxyethylamino)-6-benzylamino-9-isopropylpurine], and IκB kinase-α (IKK-α; BAY-11-7082), we show that IKK-α, but not Cdk7, is at least in part involved in estrogen-mediated phosphorylation at Ser118 in MCF-7 cells. Our data provide direct evidence for a functional role of P-Ser118-ER-α in estrogen-regulated signaling and do not support the hypothesis that resistance of breast tumors to tamoxifen therapy involves ligand independent activation of ER-α due to constitutive phosphorylation of Ser118 by constitutive activation of MAPK pathway. (Cancer Res 2006; 66(20): 10162-70)
A Novel Somatic Mouse Model to Survey Tumorigenic Potential Applied to the Hedgehog Pathway
Authors: Mao Junhao , Ligon Keith L. , Rakhlin Elena Y. , Thayer Sarah P. , Bronson Roderick T. , Rowitch David , McMahon Andrew P. 
Published: October 2006

Abstract
We report a novel mouse model for the generation of sporadic tumors and show the efficiency of this approach by surveying Hedgehog (Hh)–related tumors. Up-regulation of the Hh pathway is achieved by conditionally regulated expression of an activated allele of Smoothened (R26-SmoM2) using either sporadic leakage or global postnatal induction of a ubiquitously expressed inducible Cre transgene (CAGGS-CreER). Following postnatal tamoxifen induction, CAGGS-CreER; R26-SmoM2 mice developed tumors with short latency and high penetrance. All mice exhibited rhabdomyosarcoma and basal cell carcinoma; 40% also developed medulloblastoma. In addition, mice showed a novel pancreatic lesion resembling low-grade mucinous cystic neoplasms in humans. In contrast, widespread activation of SmoM2 in the postnatal prostate epithelium results in no detectable morphologic outcome in 12-month-old mice. Comparison of gene expression profiles among diverse tumors identified several signature genes, including components of platelet-derived growth factor and insulin-like growth factor pathways, which may provide a common mechanistic link to the Hh-related malignancies. This experimental model provides a robust tool for exploring the process of Hh-dependent tumorigenesis and the treatment of such tumors. More generally, this approach provides a genetic platform for identifying tumorigenic potential in putative oncogenes and tumor suppressors and for more effective modeling of sporadic cancers in mice. (Cancer Res 2006; 66(20): 10171-7)
Mutation Accumulation in the Intestine and Colon of Mice Deficient in Two Intracellular Glutathione Peroxidases
Authors: Lee Dong-Hyun , Esworthy R. Steven , Chu Christy , Pfeifer Gerd P. , Chu Fong-Fong 
Published: October 2006

Abstract
Mice deficient in two glutathione peroxidases (GPX), Gpx1 and Gpx2, [Gpx1/2-double knockout (DKO) mice] are prone to ileocolitis on a mixed C57BL/6 and 129S1/SvJ (B6.129) genetic background. We reported previously that ∼25% of B6.129 Gpx1/2-DKO mice develop ileocolonic tumors by 6 to 9 months of age, when their non-DKO littermates [having at least one wild-type (WT) Gpx1 or Gpx2 allele] rarely have inflammation and none have tumors. Because genetic background affects tumor susceptibility, we have generated a B6 Gpx1/2-DKO colony and discovered that these mice have fewer inflammatory cells, milder ileocolitis, and low mortality, and only 2.5% of B6 mice developed tumors. The mutant frequency of a cII reporter gene was about 2- to 3-fold higher in 28-day-old Gpx1/2-DKO and 4-fold higher in 8-month-old Gpx1/2-DKO ileal mucosa than in controls in both genetic backgrounds. In contrast, mutant frequencies in the unaffected B6 liver were not significantly different between WT and Gpx1/2-DKO mice. The mutant frequency of 8-month-old B6.129 Gpx1/2-DKO ileum was 38.94 ± 15.5−5, which was not significantly higher than the age-matched B6 ileum, 25.54 ± 10.33−5. The mutation spectra analysis has shown that B6 Gpx1/2-DKO ileum had a 3-fold increase in small nucleotide deletions at mononucleotide repeats over control B6, which are a signature mutation associated with oxidative stress. Unexpectedly, B6 Gpx1/2-DKO mice had fewer C to T transitions at CpG dinucleotides than the WT B6 (18.0% versus 40.1%; P &lt; 0.001). Our results suggest that inflammation drives gene mutations, which leads to neoplastic transformation of intestinal epithelium in the B6.129 Gpx1/2-DKO mice but rarely in the B6 Gpx1/2-DKO mice. (Cancer Res 2006; 66(20): 9845-51)
Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand Is Required for Tumor Necrosis Factor α–Mediated Sensitization of Human Breast Cancer Cells to Chemotherapy
Authors: Xu Jing , Zhou Jun-Ying , Wu Gen Sheng 
Published: October 2006

AbstractTumor necrosis factor α (TNFα) induces apoptosis and sensitizes cancer cells to chemotherapy, but the mechanism underlying its sensitization is not fully understood. Here, we report that TNFα-mediated sensitization of cancer cells to chemotherapy involves activation of the TRAIL pathway. We show that the combined treatment of breast cancer cells with TNFα and Adriamycin significantly increases cell death compared with the treatment with either agent alone. The combined treatment activated both death receptor and mitochondrial apoptotic pathways, whereas Adriamycin alone activated only the mitochondrial pathway, and TNFα failed to activate either. Furthermore, we show that TNFα induces TRAIL through a transcriptional mechanism. Using reporter gene assays in conjunction with chromatin immunoprecipitation assays, we show that TRAIL induction by TNFα is regulated via both nuclear factor-κB and Sp1 binding sites. Importantly, down-regulation of TRAIL by small interfering RNA silencing decreased TNFα-mediated Adriamycin-induced caspase activation and apoptosis, and thus enhanced breast cancer cell resistance to Adriamycin. Collectively, our results suggest that induction of TRAIL by TNFα is critical for sensitization of breast cancer cells to chemotherapy. (Cancer Res 2006; 66(20): 10092-9)
Mammary Stem Cells and Mammopoiesis
Authors: Visvader Jane E. , Lindeman Geoffrey J. 
Published: October 2006

Abstract
The isolation and characterization of mammary stem cells is fundamental to understanding mammary gland development and tissue homeostasis as well as breast oncogenesis. Recent studies have led to the prospective isolation of pluripotential stem cells from the mouse mammary gland through the identification of specific cell-surface markers and transplantation of cells into the mammary stromal microenvironment. A single cell was sufficient to reconstitute a fully developed mammary gland in vivo, indicating that combinatorial activity between independent stem cells is not essential to generate an outgrowth. Here we review the characteristics of mouse mammary stem cells, their estrogen receptor status, and the potential cellular hierarchy that exists within the mammary gland. (Cancer Res 2006; 66(20): 9798-801)
The Farnesoid X Receptor Is Expressed in Breast Cancer and Regulates Apoptosis and Aromatase Expression
Authors: Swales Karen E. , Korbonits Márta , Carpenter Robert , Walsh Desmond T. , Warner Timothy D. , Bishop-Bailey David 
Published: October 2006

AbstractBile acids are present at high concentrations in breast cysts and in the plasma of postmenopausal women with breast cancer. The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily that regulates bile acid homeostasis. FXR was detected in normal and tumor breast tissue, with a high level of expression in ductal epithelial cells of normal breast and infiltrating ductal carcinoma cells. FXR was also present in the human breast carcinoma cells, MCF-7 and MDA-MB-468. Activation of FXR by high concentrations of ligands induced MCF-7 and MDA-MB-468 apoptosis. At lower concentrations that had no direct effect on viability, the FXR agonist GW4064 induced expression of mRNA for the FXR target genes, small heterodimer partner (SHP), intestinal bile acid binding protein, and multidrug resistance–associated protein 2 (MRP-2), and repressed the expression of the SHP target gene aromatase. In contrast to MRP-2, mRNA for the breast cancer target genes MDR-3, MRP-1, and solute carrier transporter 7A5 were decreased. Although multidrug resistance transporters were regulated and are known FXR target genes, GW4064 had no effect on the cell death induced by the anticancer drug paclitaxel. Our findings show for the first time that FXR is expressed in breast cancer tissue and has multiple properties that could be used for the treatment of breast cancer. (Cancer Res 2006; 66(20): 10120-6)
Bromodomain and Histone Acetyltransferase Domain Specificities Control Mixed Lineage Leukemia Phenotype
Authors: Santillan Donna A. , Theisler Catherine M. , Ryan Amanda S. , Popovic Relja , Stuart Tara , Zhou Ming-Ming , Alkan Serhan , Zeleznik-Le Nancy J. 
Published: October 2006

Abstract
A critical unanswered question about mixed lineage leukemia (MLL) is how specific MLL fusion partners control leukemia phenotype. The MLL-cyclic AMP-responsive element binding protein–binding protein (CBP) fusion requires both the CBP bromodomain and histone acetyltransferase (HAT) domain for transformation and causes acute myelogenous leukemia (AML), often preceded by a myelodysplastic phase. We did domain-swapping experiments to define whether unique specificities of these CBP domains drive this specific MLL phenotype. Within MLL-CBP, we replaced the CBP bromodomain or HAT domain with P300/CBP-associated factor (P/CAF) or TAFII250 bromodomains or the P/CAF or GCN5 HAT domains. HAT, but not bromodomain, substitutions conferred enhanced proliferative capacity in vitro but lacked expression of myeloid cell surface markers normally seen with MLL-CBP. Mice reconstituted with domain-swapped hematopoietic progenitors developed different disease from those with MLL-CBP. This included development of lymphoid disease and lower frequency of the myelodysplastic phase in those mice developing AML. We conclude that both the CBP bromodomain and HAT domain play different but critical roles in determining the phenotype of MLL-CBP leukemia. Our results support an important role for MLL partner genes in determining the leukemia phenotype besides their necessity in leukemogenesis. Here, we find that subtleties in MLL fusion protein domain specificity direct cells toward a specific disease phenotype. (Cancer Res 2006; 66(20):10032-9)
p63 Overexpression Induces the Expression of Sonic Hedgehog
Authors: Caserta Tina M. , Kommagani Ramakrishna , Yuan Ziqiang , Robbins David J. , Mercer Carol A. , Kadakia Madhavi P. 
Published: October 2006

Abstractp63 and p73 are members of the p53 protein family and have been shown to play an important role in cell death, development, and tumorigenesis. In particular, p63 has been shown to be involved in the maintenance of epidermal stem cells and in the stratification of the epidermis. Sonic Hedgehog (Shh) is a morphogen that has also been implicated to play a role in epithelial stem cell proliferation and in the development of organs. Recently, Shh has also been shown to play an important role in the progression of a variety of cancers. In this report, we show that p63 and p73 but not p53 overexpression induces Shh expression. In particular, p63γ and p63β (both TA and ΔN isoforms) and TAp73β isoform induce Shh. Expression of Shh was found to be significantly reduced in mouse embryo fibroblasts obtained from p63−/− mice. The naturally occurring p63 mutant TAp63γ(R279H) and the tumor suppressor protein p14ARF inhibited the TAp63γ-mediated transactivation of Shh. The region −228 to −102 bp of Shh promoter was found to be responsive to TAp63γ-induced transactivation and TAp63γ binds to regions within the Shh promoter in vivo. The results presented in this study implicate p63 in the regulation of the Shh signaling pathway. (Mol Cancer Res 2006;4(10):759–68)