bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of the Retinoblastoma Pathway in Senescence Triggered by Repression of the Human Papillomavirus E7 Protein in Cervical Carcinoma Cells
Authors: Psyrri Amanda , DeFilippis Rosa Anna , Edwards Anne P. B. , Yates Kristin E. , Manuelidis Laertes , DiMaio Daniel 
Published: September 2005

Abstract
Repression of the endogenous human papillomavirus (HPV) type 18 E7 gene in HeLa cervical carcinoma cells by the bovine papillomavirus E2 transcription factor activates the retinoblastoma (Rb) pathway and induces cells to undergo senescence. To determine whether activation of the Rb pathway is responsible for senescence in response to HPV18 E7 repression, we tested the ability of wild-type and mutant E7 proteins to affect the activity of the Rb pathway and to modulate senescence in these cells. Enforced expression of the wild-type HPV16 E7 protein prevented Rb activation in response to E2 expression and impaired senescence. Importantly, there was an absolute correlation between the ability of mutant E7 proteins to inactivate the Rb pathway and to inhibit senescence in HeLa cells. Similar results were obtained in HT-3 cervical carcinoma cells. These results provide strong genetic evidence that activation of the Rb pathway is required for senescence in response to E7 repression. Hence, continuous neutralization of the Rb pathway by the E7 protein is required to maintain the proliferation of cervical carcinoma cells. Similarly, our results indicate that activation of the Rb pathway can prevent apoptosis induced by repression of the HPV18 E6 gene in HeLa cells.
Activation of Protein Kinase G Is Sufficient to Induce Apoptosis and Inhibit Cell Migration in Colon Cancer Cells
Authors: Deguchi Atsuko , Thompson W. Joseph , Weinstein I. Bernard 
Published: September 2005

Abstract
The activation of protein kinase G (PKG) by cGMP has become of considerable interest as a novel molecular mechanism for the induction of apoptosis in cancer cells, because sulindac sulfone (exisulind, Aptosyn) and certain derivatives that inhibit cGMP-phosphodiesterases and thereby increase cellular levels of cGMP appear to induce apoptosis via this mechanism. However, other effects of these compounds have not been excluded, and the precise mechanism by which PKG activation induces apoptosis has not been elucidated in detail. To directly examine the effects of PKG on cell growth and apoptosis, we generated a series of mutants of PKG Iα: PKG IαS65D, a constitutively activated point mutant; PKG IαΔ, a constitutively activated N-terminal truncated mutant; and PKG IαK390R, a dominant-negative point mutant. A similar series of mutants of PKG Iβ were also constructed (Deguchi et al., Mol. Cancer Ther., 1: 803–809, 2002). The present study demonstrates that when transiently expressed in SW480 colon cancer, the constitutively activated mutants of PKG Iβ, and to a lesser extent PKG Iα, inhibit colony formation and induce apoptosis. We were not able to obtain derivatives of SW480 cells that stably expressed these constitutively activated mutants, presumably because of toxicity. However, derivatives that stably overexpressed wild-type PKG Iβ displayed growth inhibition, whereas derivatives that stably expressed the dominant-negative mutant (KR) of PKG Iβ grew more rapidly and were more resistant to Aptosyn-induced growth inhibition than vector control cells. Stable overexpression of PKG Iβ was associated with decreased cellular levels of β-catenin and cyclin D1 and increased levels of p21CIP1. Reporter assays indicated that activation of PKG Iβ inhibits the transcriptional activity of the cyclin D1 promoter. We also found that transient expression of the constitutively activated mutants of PKG Iβ inhibited cell migration. Taken together, these results indicate that activation of PKG Iβ is sufficient to inhibit growth and cell migration and induce apoptosis in human colon cancer cells and that these effects are associated with inhibition of the transcription of cyclin D1 and an increase in the expression of p21CIP1.
Serum Proteomic Profiles Suggest Celecoxib-Modulated Targets and Response Predictors
Authors: Xiao Zhen , Luke Brian T. , Izmirlian Grant , Umar Asad , Lynch Patrick M. , Phillips Robin K. S. , Patterson Sherri , Conrads Thomas P. , Veenstra Timothy D. , Greenwald Peter , Hawk Ernest T. , Ali Iqbal U. 
Published: September 2005

Abstract
Cyclooxygenase-2 is a valid target for cancer prevention and treatment. This has been shown in preclinical and clinical cancer prevention studies by using a cyclooxygenase-2 inhibitor, celecoxib. When used in a randomized cancer prevention clinical trial on patients with the inherited autosomal dominant condition, familial adenomatous polyposis, celecoxib proved efficacious. However, a remarkable heterogeneity in patients’ responses to the chemopreventive effects of celecoxib was observed. Proteomic profiling of sera from these patients identified several markers, the expression of which was specifically modulated after treatment with celecoxib. A decision tree algorithm identified classifiers for response to celecoxib with relatively high sensitivity but moderate to low specificity. In particular, a spectral feature at m/z 16,961.4 was identified as a strong discriminator between response and nonresponse to celecoxib at the highest dose.
Simultaneous Blockade of Platelet-Derived Growth Factor-Receptor and Epidermal Growth Factor-Receptor Signaling and Systemic Administration of Paclitaxel as Therapy for Human Prostate Cancer Metastasis in Bone of Nude Mice
Authors: Kim Sun Jin , Uehara Hisanori , Yazici Sertac , Langley Robert R. , He Junqin , Tsan Rachel , Fan Dominic , Killion Jerald J. , Fidler Isaiah J. 
Published: September 2005

Abstract
Once prostate cancer metastasizes to bone, conventional chemotherapy is largely ineffective. We hypothesized that inhibition of phosphorylation of the epidermal growth factor receptor (EGF-R) and platelet-derived growth factor receptor (PDGF-R) expressed on tumor cells and tumor-associated endothelial cells, which is associated with tumor progression, in combination with paclitaxel would inhibit experimental prostate cancer bone metastasis and preserve bone structure. We tested this hypothesis in nude mice, using human PC-3MM2 prostate cancer cells. PC-3MM2 cells growing adjacent to bone tissue and endothelial cells within these lesions expressed phosphorylated EGF-R and PDGF-Rα and -β on their surfaces. The percentage of positive endothelial cells and the intensity of receptor expression directly correlated with proximity to bone tissue. Oral administration of PKI166 inhibited the phosphorylation of EGF-R but not PDGF-R, whereas oral administration of STI571 inhibited the phosphorylation of PDGF-R but not EGF-R. Combination therapy using oral PKI166 and STI571 with i.p. injections of paclitaxel induced a high level of apoptosis in tumor vascular endothelial cells and tumor cells in parallel with inhibition of tumor growth in the bone, preservation of bone structure, and reduction of lymph node metastasis. Collectively, these data demonstrate that blockade of phosphorylation of EGF-R and PDGF-R coupled with administration of paclitaxel significantly suppresses experimental human prostate cancer bone metastasis.
A Technical Triade for Proteomic Identification and Characterization of Cancer Biomarkers
Authors: Melle Christian , Ernst Günther , Schimmel Bettina , Bleul Annett , Koscielny Sven , Wiesner Andreas , Bogumil Ralf , Möller Ursula , Osterloh Dirk , Halbhuber Karl-Jürgen , von Eggeling Ferdinand 
Published: September 2005

Abstract
Biomarkers are needed to elucidate the biological background and to improve the detection of cancer. Therefore, we have analyzed laser-microdissected cryostat sections from head and neck tumors and adjacent mucosa on ProteinChip arrays. Two differentially expressed proteins (P = 3.34 × 10−5 and 4.6 × 10−5) were isolated by two-dimensional gel electrophoresis and identified as S100A8 (calgranulin A) and S100A9 (calgranulin B) by in-gel proteolytic digestion, peptide mapping, tandem mass spectrometry analysis, and immunodepletion assay. The relevance of these single marker proteins was evaluated by immunohistochemistry. Positive tissue areas were reanalyzed on ProteinChip arrays to confirm the identity of these proteins. As a control, a peak with low P was identified as calgizzarin (S100A11) and characterized in the same way. This technical triade of tissue microdissection, ProteinChip technology, and immunohistochemistry opens up the possibility to find, identify, and characterize tumor relevant biomarkers, which will allow the movement toward the clonal heterogeneity of malignant tumors. Taking this approach, proteins were identified that might be responsible for invasion and metastasis.
Different Procarcinogenic Potentials of Lymphocyte Subsets in a Transgenic Mouse Model of Chronic Hepatitis B
Authors: Nakamoto Yasunari , Suda Takashi , Momoi Takashi , Kaneko Shuichi 
Published: September 2005

AbstractThe immune response to hepatitis viruses is believed to be involved in the development of chronic hepatitis; however, its pathogenetic potential has not been clearly defined. The current study, using a transgenic mouse model of chronic hepatitis B, was designed to determine the relative contributions of the immune cell subsets to the progression of liver disease that induces hepatocellular carcinogenesis. Hepatitis B virus transgenic mice were adoptively transferred with CD4+ and CD8+ T cell-enriched or -depleted and B cell-depleted splenocytes obtained from hepatitis B surface antigen-primed, syngeneic nontransgenic donors. The resultant liver disease, hepatocyte apoptosis, regeneration, and tumor development were assessed and compared with the manifestations in mice that had received unfractionated spleen cells. Transfer of CD8+-enriched splenocytes caused prolonged disease kinetics, and a marked increase in the extent of hepatocyte apoptosis and regeneration. In 12 of 14 mice the transfer resulted in multiple hepatocellular carcinomas (HCCs) comparable with the manifestations seen in the mice transferred with total splenocytes. In contrast, mice that had received CD4+-enriched cells demonstrated lower levels of liver disease and developed fewer incidences of HCC (4 of 17). The experiment also revealed that all of the groups of mice complicated with HCC developed comparable mean numbers and sizes of tumors. B-cell depletion had no effect on disease kinetics in this model. Taken together, these results demonstrate that the pathogenetic events induced by CD8+ T-cell subset are primarily responsible for the induction of chronic liver disease that increases tumor incidence, suggesting their potential in triggering the process of hepatocarcinogenesis.
Dose-Dependent Effects of Platelet-Derived Growth Factor-B on Glial Tumorigenesis
Authors: Shih Alan H. , Dai Chengkai , Hu Xiaoyi , Rosenblum Marc K. , Koutcher Jason A. , Holland Eric C. 
Published: September 2005

Abstract
Platelet-derived growth factor (PDGF) is expressed in many different tumors, but its precise roles in tumorigenesis remain to be fully defined. Here, we report on a mouse model that demonstrates dose-dependent effects of PDGF-B on glial tumorigenesis. By removing inhibitory regulatory elements in the PDGFB mRNA, we are able to substantially elevate its expression in tumor cells using a retroviral delivery system. This elevation in PDGF-B production results in tumors with shortened latency, increased cellularity, regions of necrosis, and general high-grade character. In addition, elevated PDGF-B in these tumors also mediates vascular smooth muscle cell recruitment that supports tumor angiogenesis. PDGF receptor (PDGFR) signaling appears to be required for the maintenance of these high-grade characteristics, because treatment of high-grade tumors with a small molecule inhibitor of PDGFR results in reversion to a lower grade tumor histology. Our data show that PDGFR signaling quantitatively regulates tumor grade and is required to sustain high-grade oligodendrogliomas.
Synthesis and Evaluation of Bombesin Derivatives on the Basis of Pan-Bombesin Peptides Labeled with Indium-111, Lutetium-177, and Yttrium-90 for Targeting Bombesin Receptor-Expressing Tumors
Authors: Zhang Hanwen , Chen Jianhua , Waldherr Christian , Hinni Karin , Waser Beatrice , Reubi Jean Claude , Maecke Helmut R. 
Published: September 2005

Abstract
Bombesin receptors are overexpressed on a variety of human tumors like prostate, breast, and lung cancer. The aim of this study was to develop radiolabeled (Indium-111, Lutetium-177, and Yttrium-90) bombesin analogues with affinity to the three bombesin receptor subtypes for targeted radiotherapy. The following structures were synthesized: diethylenetriaminepentaacetic acid-γ-aminobutyric acid-[d-Tyr6, β-Ala11, Thi13, Nle14] bombesin (6–14) (BZH1) and 1,4,7,10-tetraazacyclododecane-N,N′,N″,N‴ -tetraacetic acid-γ-aminobutyric acid-[d-Tyr6, β-Ala11, Thi13, Nle14] bombesin (6–14) (BZH2). [111In]-BZH1 and in particular [90Y]-BZH2 were shown to have high affinity to all three human bombesin receptor subtypes with binding affinities in the nanomolar range. In human serum metabolic cleavage was found between β-Ala11 and His12 with an approximate half-life of 2 hours. The metabolic breakdown was inhibited by EDTA and β-Ala11-His12 (carnosine) indicating that carnosinase is the active enzyme.
Both 111In-labeled peptides were shown to internalize into gastrin-releasing peptide-receptor–positive AR4–2J and PC-3 cells with similar high rates, which were independent of the radiometal. The biodistribution studies of [111In]-BZH1 and [111In]-BZH2 ([177Lu]-BZH2) in AR4–2J tumor-bearing rats showed specific and high uptake in gastrin-releasing peptide-receptor–positive organs and in the AR4–2J tumor. A fast clearance from blood and all of the nontarget organs except the kidneys was found. These radiopeptides were composed of the first pan-bombesin radioligands, which show great promise for the early diagnosis of tumors bearing not only gastrin-releasing peptide-receptors but also the other two bombesin receptor subtypes and may be of use in targeted radiotherapy of these tumors.
Urokinase-Type Plasminogen Activator System in Breast Cancer
Authors: Gelder Marion E. Meijer-van , Look Maxime P. , Peters Harry A. , Schmitt Manfred , Brünner Nils , Harbeck Nadia , Klijn Jan G. M. , Foekens John A. 
Published: September 2005

AbstractThe prognostic value of components of the urokinase-type plasminogen activator (uPA) system, its receptor uPAR (CD87), and plasminogen activator inhibitors PAI-1 and PAI-2 is well established. We studied the predictive value of these proteolytic factors by evaluating the association of their tumor expression level and the efficacy of tamoxifen therapy in patients with recurrent breast cancer. The antigen levels of the four factors were determined by ELISA in cytosols prepared from estrogen receptor-positive primary breast tumors of 691 hormone-naive breast cancer patients with recurrent disease and treated with tamoxifen as first-line systemic therapy. High tumor levels of uPA (P &lt; 0.001), uPAR (P &lt; 0.01), and PAI-1 (P = 0.01) were associated with a lower efficacy of tamoxifen therapy. In the multivariable analysis, uPA (P &lt; 0.001) provided additional information independent of the traditional predictive factors to predict benefit from tamoxifen therapy. High levels of uPA, uPAR, and PAI-1 predicted a shorter progression-free survival (PFS) on tamoxifen in an analysis of the first 9 months of therapy. However in the analysis during the total follow-up period, high PAI-2 levels (P = 0.01) showed a longer response to tamoxifen. In conclusion, uPA, uPAR, and PAI-1, components of the urokinase system, are predictive for the efficacy of tamoxifen therapy in patients treated for recurrent breast cancer. Knowledge of their tumor expression levels might be helpful for future individualized therapy protocols, including possible new-targeted therapies based on the interference in the urokinase system.
EGF Gene Polymorphism and the Risk of Incident Primary Melanoma
Authors: Amend Kandace L. , Elder James T. , Tomsho Lynn P. , Bonner Joseph D. , Johnson Timothy M. , Schwartz Jennifer , Berwick Marianne , Gruber Stephen B. 
Published: September 2005

Abstract
Overexpression of the epidermal growth factor (EGF) pathway has been implicated in melanoma pathogenesis, and a recent case-control study identified a single nucleotide polymorphism (G to A) in the EGF gene where the G allele was associated with increased EGF expression and an increased risk of melanoma. To further evaluate this association, we conducted a case-control analysis from the Genes, Environment, and Melanoma study at the University of Michigan site using two different study designs. Incident cases of histopathologically confirmed first primary melanoma that were diagnosed between January 1, 2000 and December 31, 2000 from the University of Michigan Melanoma Clinic (n = 330) were compared with the following two different sources of nonmelanoma controls: spouse/friend controls (n = 84) and healthy volunteer controls from a case-control study of psoriasis (n = 148). Using a second analytic design, comparisons between multiple primary melanoma cases (n = 62) and single primary melanoma cases (n = 330) were also evaluated to estimate odds ratios (ORs). Genotyping for the single nucleotide substitution (G to A) at position 61 in the 5′ untranslated region of the EGF gene was performed from genomic DNA, and epidemiological risk factors were assessed through a telephone interview. When EGF genotypes were compared between incident primary melanoma cases and the nonmelanoma controls, the risk associated with the homozygous G/G genotype was not statistically significantly associated with an increased risk for incident primary melanoma compared with the homozygous A/A genotype [OR, 1.09; 95% confidence interval (CI); 0.65–1.85]. No strong associations with EGF G/G genotype were observed in comparisons of multiple primary and single primary melanoma cases (OR, 0.66; 95% CI; 0.25–1.73). Case subjects with tumors ≥3.5 mm compared with those &lt;3.5 mm were not significantly associated with the G/G genotype (OR, 0.54; 95% CI; 0.12–2.35). Our data do not support a significant association between melanoma and the EGF 61*G allele or the homozygous G/G genotype. The EGF polymorphism is not a reproducible risk factor for melanoma or thick melanoma in our data. The two analytic approaches used in the study provide evidence against a strong association between EGF 61*G and melanoma and demonstrate the potential utility of case-case designs for evaluating the role of single nucleotide polymorphisms and cancer. Additional independent studies will be required to elucidate relationships between genetic variation in the EGF gene and risk of melanoma.
Activation of the Platelet-Derived Growth Factor-Receptor Enhances Survival of Murine Bone Endothelial Cells
Authors: Langley Robert R. , Fan Dominic , Tsan Rachel Z. , Rebhun Robert , He Junqin , Kim Sun-Jin , Fidler Isaiah J. 
Published: September 2005

Abstract
The activation of the microvascular endothelial cell platelet-derived growth factor (PDGF) receptor (PDGF-R) by PDGF has been implicated in neoplastic angiogenesis. Here, we established cultures of murine bone microvascular endothelial cells and examined their response to stimulation with PDGF BB ligand and to blockade of PDGF-R signaling with the tyrosine kinase inhibitor STI571 (Gleevec). The addition of STI571 to cultures of bone endothelial cells blocked PDGF BB-induced phosphorylation in a dose-dependent manner and completely abrogated the activation of downstream targets Akt and ERK1/2. Coadministration of STI571 and Taxol also induced the activation of procaspase-3 and significant apoptosis. These data suggest that phosphorylation of PDGF-R stimulates survival pathways in bone endothelial cells and that by selectively inhibiting PDGF-R signaling with STI571, the cells are rendered sensitive to Taxol treatment. The therapeutic combination of STI571 and Taxol may be a powerful tool for targeting tumor-associated endothelial cells in the skeletal compartment.
Combination of a Poxvirus-Based Vaccine with a Cyclooxygenase-2 Inhibitor (Celecoxib) Elicits Antitumor Immunity and Long-Term Survival in CEA.Tg/MIN Mice
Authors: Zeytin Hasan E. , Patel Arti C. , Rogers Connie J. , Canter Daniel , Hursting Stephen D. , Schlom Jeffrey , Greiner John W. 
Published: September 2005

AbstractThe present study was designed to determine whether: (a) chronic administration of dietary celecoxib (Celebrex), a potent nonsteroidal anti-inflammatory drug, which targets the cyclooxygenase-2 (COX-2) enzyme, negatively impacts host immunity; and (b) celecoxib can be coupled with a poxvirus-based vaccine to impact tumor burden in a murine tumor model of spontaneous adenomatous polyposis coli. Naive mice fed the celecoxib-supplemented diets developed eosinophilia with lowered plasma prostaglandin E2 levels and reduced COX-2 mRNA expression levels in their splenic T cells. Responses of splenic T, B, and natural killer cells to broad-based and antigen-specific stimuli were, for the most part, unchanged in those mice as well as COX-2 knockout mice; exceptions included: (a) reduced IFN-γ production by concanavalin A- or antigen-stimulated T cells; and (b) heightened lipopolysaccharide response of naive B cells from mice fed a diet supplemented with 1000 ppm of celecoxib. When transgenic mice that express the human carcinoembryonic antigen (CEA) gene (CEA transgenic) were bred with mice bearing a mutation in the ApcΔ850 gene (multiple intestinal neoplasia mice), the progeny (CEA transgenic/multiple intestinal neoplasia) spontaneously develop multiple intestinal neoplasms that overexpress CEA and COX-2. Beginning at 30 days of age, the administration of a diversified prime/boost recombinant CEA-poxvirus-based vaccine regimen or celecoxib (1000 ppm)-supplemented diet reduced the number of intestinal neoplasms by 54% and 65%, respectively. Combining the CEA-based vaccine with the celecoxib-supplemented diet reduced tumor burden by 95% and significantly improved overall long-term survival. Both tumor reduction and improved overall survival were achieved without any evidence of autoimmunity directed at CEA-expressing or other normal tissues. Celecoxib is prescribed for the treatment of familial adenomatous polyposis in humans, and the CEA-based vaccines have been well tolerated and capable of eliciting anti-CEA host immune responses in early clinical studies. The results suggest that the administration of a recombinant poxvirus-based vaccine is compatible with celecoxib, and this combined chemoimmuno-based approach might lead to an additive therapeutic antitumor benefit not only in patients diagnosed with familial adenomatous polyposis but, perhaps, in other preventive settings in which COX-2 overexpression is associated with progression from premalignancy to neoplasia.