bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B42: Methotrexate inhibits histone deacetylase activity and exhibits anti-tumor activity via acetylation and stabilization of p53
Authors: Chen Ching-Chow 
Published: May 2012

Abstract
Methotrexate (MTX) is a dihydrofolate reductase (DHFR) inhibit or that has been widely used as an anti-cancer drug in different kinds of human cancers. Histone deacetylase (HDAC) overexpression is usually found in tumors, which inhibits the expression of tumor suppressor genes. HDAC inhibitors (HDACi) reactivate these tumor suppressor genes and serve as potential anticancer drugs. In the present study, we found that MTX shared structural similarity with HDACi. Molecular modeling analysis provided an evidence for the interaction of MTX with HDAC. In vitro HDAC activity assay demonstrated its inhibition on HDAC activity in various human cancer cells. The global acetylation of histone-H3 was also induced by MTX. Post-translational modification of p53 plays a critical role in regulating its activity and stability. MTX promoted p53 acetylaion at Lys 373/382 and phosphorylation at Ser15 and Ser392, then increasing its stability and transcriptional activity. Stabilized p53 further induced the expression of its downstream gene, p21. MTX induced apoptosis and inhibited cell viability, which was dependent on p53 expression. This study provides the first time that MTX acts as a HDACi. In addition, MTX induces p53 acetylation and stabilization, and mediates p53-dependent apoptosis and growth inhibition in human cancer cells.
Citation Information: Cancer Res 2009;69(23 Suppl):B42.
Abstract B46: Essential roles of SIRT1 for BCR-ABL transformation and genetic mutations
Authors: Wang Zhiqiang , Yuan Hongfeng , Modi Hardik , Bhatia Ravi , Chen WenYong 
Published: May 2012

Abstract
Resistance of cancer stem cells and acquired genetic mutations are daunting challenges facing targeted cancer therapy, but the underlying mechanisms are not clear. This is best exampled by the tyrosine kinase inhibitor imatinib that effectively treats chronic myelogenous leukemia (CML) whereas resistance develops due to persistence of CML stem/progenitor cells and acquired mutations of BCR-ABL. SIRT1 is a mammalian stress response gene homologous to yeast silent information regulator 2 (Sir2), a nicotinamide adenine dinucleotide (NAD+) dependent protein deacetylase, and is involved in regulation of a variety of cellular functions including survival, glucose homeostasis and fat metabolism through deacetylating histones and non-histone target proteins. Here we demonstrate that BCRABL transformation activates SIRT1 in hematopoietic stem/progenitor cells in both clinical CML patients and a CML-like disease mouse model. Inhibition of SIRT1 by gene knockdown or pharmacological inhibitors suppresses CML cell proliferation and induces apoptosis in vitro. SIRT1 knockdown inhibits growth of CML tumor xenograft in immunodeficient mice. Homozygous knockout of SIRT1 gene inhibits BCR-ABL transformation of mouse bone marrow cells and the development of a CML-like myeloproliferative disease. We show that through deacetylation of Ku70, SIRT1 promotes BCR-ABL mutations upon imatinib treatment and de novo genetic mutations upon DNA damage. Our results suggest an essential role of SIRT1 for BCR-ABL oncogenic transformation and promoting cancer genome instability, and have implication for targeting SIRT1 to overcome resistance. These findings not only improve our understanding of SIRT1 functions in tumorigenesis, but also have translational implication for targeting SIRT1 for overcoming resistance in cancer treatment.
Citation Information: Cancer Res 2009;69(23 Suppl):B46.
Abstract B49: Smad4 suppresses Wnt signaling through downregulation of β-catenin
Authors: Smith J. Joshua , Freeman Tanner J. , Deane Natasha G. , Zi Jinghuan , Poon Sabrina , Chen Steven , Kis Christian , Lee Ethan , Dhawan Punita , Washington Mary Kay , Shyr Yu , Beauchamp R. Daniel 
Published: May 2012

Abstract
Introduction: Transforming Growth Factorβ (TGFβ) and Wnt signaling pathways modulate differential responses during embryonic development, and later in intestinal epithelial cell differentiation, proliferation and colorectal tumor promotion. β-catenin, the central mediator of canonical Wnt signaling, has been shown to pathologically promote intestinal epithelial cell de-differentiation and induce sustained proliferation in the absence of functional APC. Smad proteins are key developmental proteins involved in TGFβ/Bone Morphogenetic Protein (BMP) signaling involved in epithelial cell growth inhibition. Smad4, in particular, functions as a tumor suppressor and mutation of the Smad4 gene is a frequent and potentially late event in colon cancer. We recently found that expression of wild type Smad4 in Smad4-mutant colon cancer cells results in profound inhibition of β-catenin/TCF-driven transcriptional activation.
Purpose: In the current study, we set out to determine the mechanism of Smad4 inhibition of canonical Wnt signaling.
Experimental Procedures: We examined steady-state levels of β-catenin mRNA and protein in cells and human tissues, followed by analysis of components of β-catenin transcriptional and degradation machinery in the presence and absence of Smad4, and with and without inhibition of GSK3-β, a critical regulator of cytoplasmic β-catenin.
Results: We observed that wild type Smad4 expression resulted in significant repression of Wnt-specific transcriptional activity that could be restored with GSK-3β inhibition and overexpression of wild-type and mutant β-catenin in S W480 cells that have inactivating mutations in both APC and Smad4 genes. Transient overexpression of Smad4 also inhibited β-catenin-dependent transcriptional activity in HEK 293 cells that have wild-type APC and Smad4 genes. β-catenin phosphorylation is intact and unchanged in comparison of controls and Smad4-expressing S W480 cells, but the total level of β-catenin mRNA and protein is decreased in the Smad4-expressing cells. Assessment of human colorectal cancers using tissue microarray analysis revealed an inverse relationship between nuclear Smad4 and tumor cell β-catenin immunostaining. Furthermore, we observed that high Smad4 expression is associated with better disease-free survival and that high β-catenin expression is associated with worse disease-specific survival in analysis of outcomes from 250 patients.
Conclusions: Our data suggest that the tumor suppressor role of Smad4 involves reduction of β-catenin levels with resultant reduction of β-catenin/TCF-mediated transcriptional activity, and this regulatory mechanism has an important impact on clinical outcomes in colorectal cancer.
Citation Information: Cancer Res 2009;69(23 Suppl):B49.
Abstract B50: Smurf2-deficient mice exhibit increased tumorigenesis
Authors: Ramkumar Charusheila , Zhang Hong 
Published: May 2012

Abstract
Smurf2, a HECT family E3 ubiquitin ligase has been shown to ubiquitinate and target for degradation several proteins that promote tumorigenesis, including TGF-β receptors, Smad2/3, β-catenin, and Mad2. Furthermore, we have found previously that Smurf2 can induce senescence in early passage cells in culture. As senescence has been postulated to act as a tumor suppression mechanism, we hypothesized that Smurf2 functions as a tumor suppressor. To test this hypothesis, we generated a Smurf2-deficienct mouse strain using a gene trapping strategy. The homozygous Smurf2-deficient mice were obtained with the expected Mendelian ratio after intercrossing of heterozygous mice, and they exhibited no obvious developmental defects. Analysis of mouse embryonic fibroblasts from these Smurf2-deficient mice revealed that they exhibited delayed senescence entry and consequently had an increased tendency to immortalize in culture. Cohorts of Smurf2-deficient and wild-type mice were monitored for spontaneous tumor development. In this ongoing study, 20% (7 out of 35) of the Smurf2-deficient mice, but none of the wild-type mice showed signs of morbidity after 14-months of age. The moribund Smurf2-deficient mice were found to have enlarged spleen, pale kidneys and liver, and/or enlarged lymph nodes. Histopathology analysis indicated that most of the tumors are lymphomas. In addition, we found adenocarcinoma of the intestine in one Smurf2-deficient mouse. Collectively, our data suggest that Smurf2 is a tumor suppressor. The investigation of the mechanism by which Smurf2 deficiency leads to tumorigenesis is ongoing.
Citation Information: Cancer Res 2009;69(23 Suppl):B50.
Abstract B55: The impact of inactivation of p53 and PTEN tumor suppressors on promotion and progression of human non-small cell lung carcinoma
Authors: Andjelkovic Tijana , Bankovic Jasna , Milinkovic Vedrana , Podolski Ana , Ruzdijic Sabera , Tanic Nikola 
Published: May 2012

Abstract
Lung cancer is the major cause of cancer-related death worldwide and the five-year survival rate is not improving significantly, remaining at about 15% for all stages. Inactivation of p53 and PTEN (phosphatase and tensin homolog deleted on chromosome 10) tumor suppressors are molecular events highly related to the pathogenesis of lung cancer, particularly to non-small cell lung carcinoma (NSCLC). However, we still do not have clear image of the sequence of events in NSCLC promotion and progression, that is, whether inactivation of either of these tumor suppressors is early or late event and what the impact of these events is on NSCLC pathogenesis and patients survival. Therefore, we analyzed mutational inactivation of p53 and inactivation of PTEN by loss of heterozygosity (LOH) in 30 NSCLC patients and correlated obtained data with histopathological parameters that are indicators of initiation and progression of the disease: histological subtype, tumor grade, tumor stage, lymph node invasion and necrosis. PCR-single strand conformation polymorphism (PCR-SSCP) analyses revealed and sequencing procedures confirmed that 33.3% of patients had mutationaly inactivated p53 while fragment analysis of PTEN showed that 43.3% had inactivated PTEN by LOH. In total population of analyzed patients, 13.3% of them carried inactivated p53 only, 23.3% had inactivated PTEN only, while 20.0% of patients had inactivated both tumor suppressors. These data suggest that inactivation of PTEN, either alone or in combination with the inactivation of p53, prevalently occurs in NSCLC. Correlation analyses imply that inactivation of either p53 or PTEN is an early event in pathogenesis of NSCLC, while inactivation of both tumor-suppressors contributes to further tumor progression. In addition, correlation analysis of inactivated PTEN and p53 with the degree of genomic instability of each patient (obtained in previous study) disclosed that mutated p53 is associated with high genomic instability while inactivated PTEN was more frequent in patients with low genomic instability confirming important role of p53 in maintaining the stability of the genome. Finally, Kaplan & Meyer survival analyses revealed that patients with inactivated p53 have much worse prognoses. In order to conclude the study of p53 and PTEN inactivation, analyses of hypermetylation of PTEN promoter and LOH of p53 gene are underway.
Citation Information: Cancer Res 2009;69(23 Suppl):B55.
Abstract B59: Role of Nf1 signaling in regulating pigmentation in the mouse
Authors: Deo Mugdha A. , Fuchs Helmut , Hrabe Martin H. , Barsh Gregory S. , Van Raamsdonk Catherine D. 
Published: May 2012

Abstract
Introduction: Neurofibromatosis type 1 (NF1) is one of the most common autosomal dominantly inherited disorders affecting 1 in 3500 individuals. The NF1 gene encodes a protein called neurofibromin that has a Ras-GAP activity and acts as a tumor suppressor by negatively regulating Ras. Loss of neurofibromin has a pleiotropic effect affecting a number of cell types. We are interested in using the elegance and sensitivity of the pigmentary system to understand the mechanisms by which Nf1 regulates cell survival and proliferation in vivo. We have found that an ENU-induced point mutation (Nf1Dsk9) or a targeted knockout of one Nf1 allele specifically and uniformly darken the mouse skin dermis. The Endothelin receptor B (Ednrb) is essential for melanocyte (pigment producing cell) survival in the dermis between E10–E12.5. Since Nf1Dsk9 causes uniform hyper pigmentation of the dermis, we wanted to know whether Nf1Dsk9 depends on Ednrb signaling to cause dermal hyper pigmentation. In an attempt to understand the effect of homozygous loss of Nf1 on melanocytes, we knocked Nf1 out specifically in melanocytes.
Methods: The Nf1Dsk9/+ mice were crossed to Ednrbs-l/s-l mice that have a complete deletion of the Ednrb gene. Pigmentation of the dermal tail skin and coat color spotting of 2–3 week old mice obtained from the above cross was quantified using ImageJ.
A melanocyte-specific knockout of Nf1 was made in vivo in the mouse by crossing existing Mitf-Cre line to the floxed-Nf1 line. Pigmentation of the dermal tail skin was quantified using ImageJ.
Results: A significant (p&lt; 0.05, T-Test) hyper pigmentation of the dermis was observed in the Mitf-Cre/+; Nf1flox/flox homozygotes (now called Nf1mcko/mcko) with no change in epidermal pigmentation. In contrast to the Nf1Dsk9/+(germline heterozygote), the Nf1mcko/+ (melanocyte-specific knockout heterozygote) does not show dermal hyper pigmentation.
Comparison of the tail dermis of Nf1Dsk9/+;Ednrbs-l/s-l mice with +/+;Ednrbs-l/s-l mice showed that Nf1Dsk9 was unable to give a dark dermis in the absence of Ednrb. However, the Nf1Dsk9/+;Ednrbs-l/s-l mice showed a significant (p&lt; 0.05, T-Test) increase in the percentage of coat that was pigmented.
Discussion: A significant darkening of the dermis in the Nf1mcko/mcko compared to wild type or Nf1mcko/+ littermates suggests a cell autonomous mechanism of dermal hyper pigmentation in the homozygote caused by the loss of Nf1 in melanocytes.
The Nf1mcko/+ heterozygote does not show dermal hyper pigmentation, unlike the Nf1Dsk9/+ heterozygote. This suggests that the effect of loss of Nf1 in melanocytes acts in a non-cell autonomous mechanism in the heterozygote.
The lack of dermal hyper pigmentation but an increased percentage of coat color spotting in the Nf1Dsk9/+;Ednrbs-l/s-l mice suggests that Nf1 regulates pigmentation by two independent mechanisms, one that depends on Ednrb and one that does not.
Citation Information: Cancer Res 2009;69(23 Suppl):B59.
Abstract B60: Suppressing malignant progression of prostate cancer by inhibiting expression of OPN and S100A4
Authors: Zhang Yu , Forootan Shiva S. , Foster Christopher , Ke Youqiang 
Published: May 2012

Abstract
The potential of using OPN and S100A4 as therapeutic targets has been tested in this study. Constructs expressing short silencing RNAs targeting OPN and S100A4 respectively were transfected into DU145 cells which express high levels of both OPN and S100A4 prior to the transfection. In the two established S100A4 transfectant lines, named SDRC2 and SDRC11 respectively, the level of S100A4 was reduced by 28- and 4- fold, compared with the control. In the two OPN-suppressed transfectants, named ODRC4 and ODRC10 respectively, the expression of OPN was either reduced by 8 times or almost completely suppressed. When tested in vitro, suppression of either OPN or S100A4 significantly inhibited the tumourigenicity and invasiveness, but not the motility and proliferation rate of the cancer cells. When inoculated in nude mice, all OPN-suppressed and S100A4-suppressed transfectants produced smaller tumors compared to the control group. Tumors produced by ODRC4 cells and ODRC10 cells showed significant reduction by 6- and 2.8- times in the average size compared to the control; and the difference between the average size of the tumors produced by OPN-moderately-suppressed ODRC4 cells and that produced by OPN-highly-suppressed ODRC10 cells was significant. The average size of tumors produced by S100A4-moderately-suppressed SDRC11 cells was reduced by 7.3 times while that produced by S100A4-highly-suppressed SDRC2 cells was only mild. Western blot and immunocytochemistry staining showed that the patterns of OPN and S100A4 expressions in tumor tissues were very similar to those correspondent cell lines inoculated. These results suggested that the inhibition of either OPN or S100A4 can suppress tumourigenicity of prostate cancer cells. While the tumor sizes appeared to be reduced as the reducing level of OPN, the tumor-suppressing and the S100A4-reduction did not exhibit a linear relationship. While the maximum tumor suppression was achieved when the level of S100A4 was reduced to the level similar to that expressed in benign cells, further S100A4 suppression did not appear to have any further effect on tumor size. Separate studies on the relationship between OPN and S100A4 indicated that S100A4 and OPN may promote the development and malignancy progression of prostate cancer in a coordinated manner. Our work suggested that both S100A4 and OPN may be potential targets for tumorgenecity-suppression.
Citation Information: Cancer Res 2009;69(23 Suppl):B60.
Abstract B61: Regulation of mammary stem/progenitor cells by p53
Authors: Tao Luwei , Roberts Amy , Dunphy Karen , Yan Haoheng , Jerry D. Joseph 
Published: May 2012

Abstract
Introduction: Breast cancer is the most frequent cancer among women in the United States. Understanding the biological behavior of mammary stem cells (MaSCs) and progenitor cells sheds light on the mechanism of mammary gland malignant transformation. The p53 tumor suppressor protein (TP53 in human, Trp53 in mouse) regulates cell growth and protects cells from malignant transformation and has been shown to also participate in regulation of tissue-specific stem cells.
Methods: Total mammary cells were isolated from 8–10 weeks old mice of different p53 genotype (Trp53+/+, Trp53+/−, Trp53−/−). Mammosphere assay were used to compare the self-renewal and ionizing radiation (IR) response of mammosphere-initiating cells. Limiting dilution and transplantation was done to compare the frequency of long-term regenerative mammary stem cells of Trp53+/+ and Trp53−/− epithelium. 3 weeks old BALB/c Trp53+/+ and Trp53−/− mice were injected with BrdU for 7 consecutive days and chased for 9 weeks. BrdU staining was done to compare the frequency of label-retaining cells in their mammary glands.
Results: Mammosphere assays showed that decreased p53 dosage in Trp53+/− and Trp53−/− mice led to increased numbers and size of mammospheres. Meanwhile, the number of secondary and tertiary mammospheres was not affected by (IR) regardless of their genotype. Serial dilution and transplantation experiments also showed that the Trp53−/− epithelium had significantly increased frequency of long-term regenerative MaSCs compared to Trp53+/+ epithelium. The BrdU labeling experiment showed that Trp53−/− mammary gland contains less label-retaining epithelial cells (LRECs) than Trp53+/+ epithelium.
Conclusions: Our data suggest that p53 negatively regulates the self-renewal of mammary stem cells. The MaSCs pool expands with decreased p53 dosage, which may results in a higher transformation risk. Meanwhile, the p53-mediated apoptosis pathway is compromised in the mammosphere-initiating cells, suggesting different functional status of p53 in cells of different differentiation stage.
Citation Information: Cancer Res 2009;69(23 Suppl):B61.
Abstract B62: WWOX expression suppresses tumorigenecity by inducing apoptosis and attenuating migration of metastatic cells
Authors: Abdin Suhaib , Salah Zaidoun , Aqeilan Rami 
Published: May 2012

Abstract
The WW domain-containing oxidoreductase (WWOX) spans one of the most active common fragile sites, FRA16D, involved in cancer. WWOX encodes a 46-kDa protein that contains two N-terminal WW domains and a central short-chain dehydrogenase/reductase (SDR) domain. Through its WW domain, Wwox interacts with its partners and modulates their functions; mainly by suppressing their transactivation functions through sequestering them in the cytoplasm. Wwox expression is absent or reduced in most cancer cells and its ectopic overexpression induces apoptosis in vitro and suppresses tumorigenecity in vivo suggesting tumor suppressor function of WWOX. Recently we demonstrated that targeted deletion of the Wwox gene in mice causes increased spontaneous tumor incidence confirming WWOX as a bona fide tumor suppressor. Furthermore, Wwox attenuates the migration and invasion ability of MDA-MB-231 breast carcinoma metastatic cells. In addition, its restoration results in reduced attachment and migration on fibronectin. By contrast, knocking down endogenous Wwox increases adhesion to fibronectin. Therefore, Wwox acts as a tumor suppressor not only by inducing apoptosis mediated by caspase activation but also through modulating the interaction between tumor cells and the extracellular matrix.
Citation Information: Cancer Res 2009;69(23 Suppl):B62.
Abstract B72: A computational approach integrating proteomic, transcriptional, and interactome data for discovery of cellular signaling networks
Authors: Huang Shao-shan Carol , Fraenkel Ernest 
Published: May 2012

Abstract
Cellular signaling and transcription are tightly integrated processes that have profound effects on every stage of tumor development and growth. Although there are now a variety of high-throughput methods for studying these processes, our knowledge of them remains fragmentary. Typically, the vast majority of hits identified by transcriptional, proteomic and genetic assays lie outside of the expected pathways. These unexpected components of the cellular response are often the most interesting, as they can provide new insights into biological processes and potentially reveal new therapeutic approaches. However, they are also the most difficult to interpret. We present a technique, based on the Steiner tree algorithm, that uses previously reported protein-protein interactions to determine how these hits are organized into functionally coherent pathways, revealing many components of the cellular response that are not readily apparent in the original data. Applied to simultaneously to phosphoproteomic and transcriptional profiling data for the yeast pheromone response, it identifies changes in diverse cellular processes that extend far beyond the expected pathways. We expect our current analysis of the experimental data from epidermal growth factor (EGF) signaling network in non-tumorigenic and tumorigenic cells will shed light on the regulation of cellular processes at the global level and the consequences of oncogenic mutations on signaling and transcription.
Citation Information: Cancer Res 2009;69(23 Suppl):B72.