bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract C191: The effect of the cyclin-dependent kinase inhibitor PD 0332991 on glioblastoma cells and relationship with p15INK4B/p16INK4A expression
Authors: Cen Ling , Ostrem Jamie L. , Schroeder Mark A. , Mladek Ann C. , Fink Stephanie R. , Jenkins Robert B. , Sarkaria Jann N. 
Published: June 2012

Abstract
Glioblastoma multiforme (GBM) is the most common and highly malignant primary brain tumor in adults with a median survival just over 1 year, and novel therapies are urgently needed. Deregulation of the p16 (INK4A)-CDK4/6-pRb pathway are commonly found in human GBM patients and selective inhibitors of CDK4/6 may be specifically useful to suppress proliferation associated with these alterations. PD0332991 is an orally active small molecule that specifically inhibits CDK4 and CDK6. Therefore, the efficacy of PD0332991 was evaluated in the Mayo panel of primary GBM xenograft lines using short-term explant cultures. We hypothesized that expression of p15 and/or p16, endogenous inhibitors of CDK4/6 activity, would suppress the response of GBM tumors to PD0332991 treatment. To test this hypothesis, 2 GBM xenograft cell lines with wild-type p16/p15 levels (GBM5 and 28) and 2 lines without detectable p16/p15 levels (GBM22 and 43) were selected for further analysis. Tumor cells were treated with graded concentrations (10 nanoM to1 microM) of PD0332991 for 5 days and subjected to CyQUANT cell proliferation assays. Consistent with our hypothesis, treatment with 1 microM PD0332991 effectively inhibited cell proliferation to 56.6±3.5% (P&lt;0.001) and 44.3±3.4% (P&lt;0.001) of control in GBM22 and GBM43 cells respectively, but did not affect cell proliferation in GBM5 and GBM28 cells (98.7±15.6% and 101.8±12.0% of control, respectively). In addition, 1 microM PD0332991 induced G1-phase cell cycle arrest in GBM22 (treated 79.7±0.8% vs. control 63.4±0.5% of cells in G1 phase, P&lt;0.001) and GBM43 (treated 70.6±1.1% vs. control 48.9±4.6% of cells in G1 phase, P&lt;0.001) but not in GBM5 and GBM28 (treated 52.3±2.7% vs. control 54.0±5.1%, treated 52.4±4.7% vs. control 54.6±2.6%, respectively). The status of p15 and p16 was confirmed by RT-PCR, which demonstrated readily detectable expression of p15 and p16 in GBM5 and GBM28, but not in GBM22 and GBM43 cells. Additional comparative genomic hybridization (CGH) data showed that CDKN2A and 2B (genes encode for p16 and p15 respectively) are homozygously deleted in GBM22 and 43, hemizygously deleted in GBM5 and normal in GBM28. We also examined the status of CDK4, CDK6, pRb and other molecules in the p16-CDK4/6-pRb pathway by Western, RT-PCR and CGH in these GBM lines and the data will be presented. We are now testing whether shRNA knockdown and/or re-expression of p15/p16 in the relevant cell lines alters their responsiveness to PD0332991. In conclusion, CDK4/6 inhibitor PD0332991 inhibits cell proliferation and induces G1 cell cycle arrest in p15/p16- null GBM tumors, but is less effective in p15/p16 expressing tumors.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C191.
Abstract C198: CX-4945, a novel small molecule inhibitor of CK2 protein kinase, reduces hyperactivated Akt signaling and synergizes with Akt inhibitors in breast cancer cells
Authors: Drygin Denis , Bliesath Josh , Ho Caroline , Siddiqui-Jain Adam , O'Brien Sean , Omori Mayuko , Huser Nanni , Proffitt Chris , Streiner Nicole , Rice William G. , Anderes Kenna 
Published: June 2012

Abstract
Akt, a critical protein kinase in the PI3K signaling pathway regulates multiple biological processes that are important in tumorigenesis. This “Master Regulator Kinase” is often hyperactivated in cancer through various mechanisms, including mutations or deletions in Akt, PI3K or PTEN tumor suppressor. The last decade witnessed the emergence of another “Master Regulator Kinase” - CK2. Like Akt, CK2 controls the growth, proliferation and survival of cancer cells. Ironically, CK2 regulates Akt through phosphorylation and down regulation of PTEN and via direct and specific phosphorylation of Akt at Ser129. This phosphorylation event by CK2 further stimulates the activity of Akt, thereby enhancing the “driver effect” of Akt in promoting oncogenic signaling. Unlike Akt, CK2 does not require phosphorylation for activation but rather its activity appears to be regulated through expression levels. Due to the unique shape of the ATP-binding site and an incomplete understanding of the regulation of CK2 expression, pharmacological targeting of CK2 has proven to be very challenging. To date only one small molecule inhibitor of CK2, CX-4945, has advanced into clinical development. Herein, we describe the pharmacological characterization of CX-4945, its impact on Akt signaling and implications for combination therapies.
The high incidence of abnormalities found in the PI3K pathway in breast cancers and the distinct roles that CK2 and Akt play in this disease have made it an attractive tumor type to study the effects of CX-4945. A cell viability screen of 16 diverse but genetically well-characterized breast cancer lines revealed that cells carrying mutations causing Akt-activation were significantly more sensitive to CX-4945 than those that did not. Western blot analyses of these cell lines demonstrated good correlation between the phosphorylation of Akt at Ser129 and expression of catalytic subunits of CK2. Treatment with CX-4945 resulted in dramatic reductions of phosphorylation of Akt at Ser129 and reductions in phosphorylation of the downstream targets of Akt, e.g. p21. Upon combination of CX-4945 with inhibitors that targeted the PI3K/Akt pathway, we observed synergistic antiproliferative activity in breast cancer cells. Thus, evaluation of the effects of CX-4945 on the Akt pathway in breast cancer cell lines may allow for the identification of patient populations more sensitive to CX-4945 and guide the selection of more effective combination therapies for cancer patients.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C198.
Abstract C199: Development of potent, small-molecule inhibitors of ETK
Authors: Vollmer David , Bearss Jared , Jones Carissa , McCarthy Virgil , Shi Chongtie , Tang Chunlin , Gourley Eric , Liu Xiao-Hui , Hewitt William , Vankayalapati Hariprasad , Warner Steven , Olsen Colin , Bearss David 
Published: June 2012

Abstract
Epithelial and endothelial tyrosine kinase (Etk) is a nonreceptor tyrosine kinase that plays a central role in the proliferation, differentiation, apoptosis, and tumorigenicity of epithelial cells. Inhibition of Etk signaling can result in impaired cellular transformation, down-regulation of angiogenesis, and increased apoptosis. Employing our proprietary CLIMB™ technology, a computationally driven drug discovery process, we designed and synthesized approximately 35 small molecules for ETK-inhibition testing in biochemical and cellular assays. Most of these compounds exhibited low nanomolar activity and selectivity across a wide panel of kinases. Five compounds were subsequently chosen for further evaluation in in vivo studies. As predicted from CLIMB™, all of the compounds showed sufficient tolerability and pharmacokinetics in mice to advance into tumor efficacy studies. Endometrial and hepatocellular cancers were selected for these studies based on previous in vitro results indicating high ETK expression and potent compound activity. All five compounds demonstrated marked activity in these models; in one cell line, two of the compounds inhibited tumor growth by more than 50% after less than two weeks of dosing. Using these same tumor lines in pharmacodynamic studies, the compounds also showed significant modulation of cellular transformation and anti-apoptotic markers consistent with ETK inhibition. Moreover, quantitative analysis of microvessel density, a key indicator of angiogenesis, demonstrated clear inhibition of blood vessel formation from tumors excised after treatment with the five compounds. Utilizing our CLIMB™ technology, we have rapidly developed a new class of potent inhibitors that consistently demonstrate in vivo activity against ETK-relevant tumor cell lines.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C199.
Abstract C201: A novel potent and selective inhibitor of PI3K/mTOR, GDC-0980, currently in phase I clinical trials
Authors: Friedman Lori S. , Belvin Marcia , Berry Leanne , Berry Megan , Castanedo Georgette , Edgar Kyle , Folkes Adrian , Guan Jane , Heffron Tim , Lesnick John , Lewis Cris , Nonomiya Jim , Olivero Alan , Patel Sonal , Pang Jodie , Prior Wei Wei , Salphati Laurent , Sampath Deepak , Sutherlin Dan , Wallin Jeff , Zhu Bingyan 
Published: June 2012

Abstract
Introduction: The phosphoinositide-3 kinase (PI3K)/Akt signaling pathway is deregulated in a wide variety of cancers. Somatic activating mutations and amplifications in PI3K are common in multiple cancers including breast, colon, and lung cancer. PTEN, a phosphatase that converts PIP3 to PIP2 and thus has an opposing function to PI3K, is a commonly mutated tumor suppressor in multiple cancers including prostate and glioblastoma. Alterations of this pathway have been implicated in tumor initiation, progression, survival, angiogenesis, and metastasis. PI3K/Akt pathway activation has also been implicated in therapeutic resistance. Thus PI3K is considered to be a promising therapeutic target for cancer.
Summary of Results: Medicinal chemistry efforts resulted in the discovery of GDC-0980, a selective, orally bioavailable inhibitor of PI3 Kinase and mTOR kinase with promising pharmacokinetic and pharmaceutical properties. Here we report the first pre-clinical profile of GDC-0980. This compound is a potent ATP-competitive Class I PI3 kinase inhibitor with an IC50 of 4.8 nM against the PI3K p110apha subunit, 26.8 nM p110beta, 6.7 nM p110delta, 13.8 nM p110gamma, and an mTOR Kiapp of 17.3 nM. GDC-0980 demonstrates selectivity against a large panel of protein kinases as well as selectivity over PIK family kinases including Class II, Class III, and DNA-PK. GDC-0980 inhibits the PI3K signaling pathway in vitro causing a reversible G1 cell cycle arrest, and apoptosis induction in a subset of tumor cell lines. Levels of signaling pathway markers such as phosphorylated AKT (pAKT), PRAS40 (pPRAS40), and S6 (pS6) are rapidly and dramatically reduced following exposure of cells to GDC-0980. Oral dosing of GDC-0980 potently inhibits tumor growth in xenograft models including those mutated in PI3K and PTEN, and elicits an exposure-related concomitant decrease in PD biomarkers.
Conclusion: These preclinical data provide compelling evidence in support of GDC-0980 as a clinical candidate, and Phase I studies are ongoing.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C201.
Abstract C203: Inhibition of TTK activates the p53 pathway
Authors: Williams Brandi L. , Rogers Aaron , Cassiano Jared , Tardif Keith D. , Roth Bruce L. , Saunders Michael , Hoarau Christophe , Kumar D. Vijay 
Published: June 2012

Abstract
Background: TTK, also known as Mps1, is a dual-specificity kinase that is essential for the proper amphitelic attachment of chromosomes to the mitotic spindle during mitosis and for preventing anaphase progression until the chromosomes are properly attached. Given the role of TTK in genome integrity, we evaluated the effect of MPI-0479605, a potent and selective inhibitor of TTK, on the p53 pathway.
Materials and Methods: For image analysis, cells were fixed and stained with Hoechst dye and anti-β-tubulin and anti-pericentrin antibodies. Images were taken on a BD Pathway high content imaging system. For cell cycle analysis, cells were fixed, stained with propidium iodide and analyzed by FACS. For Western blot analysis, cell lysates were run on SDS-polyacrylamide gels and proteins were transferred to PVDF membrane. Membranes were probed with the indicated antibodies.
Results: Inhibition of TTK induced severe defects in chromosome segregation, as shown by the presence of lagging chromosomes and/or anaphase bridges during mitosis and the formation of micronuclei at interphase. Anaphase bridges may result in DNA double-strand breaks. Cell cycle analysis showed that a subpopulation of treated cells exhibited a tetraploid phenotype. Because either DNA damage or tetraploidy may induce the p53 pathway, we examined whether p53 was induced by treatment with MPI-0479605. Expression of p53 was induced in a dose- and time-dependent manner in response to MPI-0479605, with maximal levels occurring between 24 and 48 hours of treatment. Induction of p53 correlated with an increase in p21 expression and a decrease in survivin protein levels, indicating that p53 is transcriptionally active. Using phosphospecific antibodies, we determined that p53 is phosphorylated on Ser15 in response to MPI-0479605 treatment but not Thr18, Ser20, Ser37 or Ser46. Phosphorylation of γH2AX at Ser139, which is a marker for the presence of double-strand DNA breaks, was induced by treatment with MPI-0479605 in a time-dependent manner similar to p53 induction. Phosphorylation of p53 on Ser15 and H2AX on Ser139 can be mediated by the DNA damage checkpoint protein ATM. ATM also phosphorylates Chk2 on Thr68 and induces its activity, but, treatment with MPI-0479605 did not induce an increase in Chk2 Thr68 phosphorylation.
Conclusions: Treatment of cells with the small molecule TTK inhibitor, MPI-0479605, activates p53. This may be due to chromosome segregation defects, which cause subsequent DNA double strand breaks and/or tetraploidy. In response to TTK inhibition, we observe an increase in H2AX phosphorylation, followed by the phosphorylation (Ser15) and activation of p53. Given that inhibition of TTK induces an apoptotic cell death, activation of p53 may be one mechanism by which the apoptotic pathway is induced in response to MPI-0479605.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C203.
Abstract C206: In vivo activity of SGI-1252, a potent, small-molecule dual inhibitor of JAK2 and ALK2
Authors: David Vollmer , Bearss Jared , Jones Carissa , McCarthy Virgil , Gourley Eric , Liu Xiao-Hui , Vankayalapati Hariprasad , Warner Steven , Olsen Colin , Bearss David 
Published: June 2012

Abstract
Activation of JAK2, an intracellular protein tyrosine kinase, is known to induce cell proliferation and apoptosis and it has been shown to be mediated by pro-inflammatory cytokines. JAK2 dysregulation is implicated in myeloproliferative disorders, solid tumor malignancies, and autoimmune diseases. Utilizing our proprietary CLIMB™ technology, a computationally driven drug discovery process, we have rapidly designed and developed, SGI-1252, a potent oral inhibitor which exhibits low nanomolar in vitro activity against all of the JAK kinase family, except JAK3. Additionally, it has low nanomolar activity against ALK2, a high-affinity binding receptor for bone morphogenic protein. As predicted from computational models, SGI-1252 is well tolerated across several rodent species and demonstrates a wide safety margin in both short- and long-term toxicity studies. Acute maximum tolerated doses of greater than 900 mg/kg are observed in mice and rats dosed orally with SGI-1252. Over a 5-week period, daily oral dosing of up to 200 mg/kg SGI-1252 shows no hematological toxicity and no body weight loss in mice. Pharmacokinetic studies of SGI-1252 in rodents also demonstrate excellent systemic exposure, with oral bioavailabilities of greater than 50% in mice and rats. Because inflammatory cytokines are known to play a role in the pathogenesis of pancreatic and lung cancers, tumor xenograft models of those cell lines were evaluated. In BxPC3 and A549 xenografts, three weeks of daily oral dosing of 200 mg/kg SGI-1252 demonstrate exceptional activity, with tumor inhibitions of greater than 50% in both models. Pharmacodynamic studies were also performed to further elucidate the effect of SGI-1252 on pro-inflammatory cytokines related to these models. In several acute-phase mouse models, where turpentine-oil injection are utilized for cytokine stimulation, SGI-1252 is observed to down-regulate IL-6 and VEGF expression 16–24 hours after dosing. In summary, SGI-1252 is a potent oral inhibitor that is well tolerated in rodent models, provides excellent PK exposure, and demonstrates tumor growth inhibition as well as modulation of pro-inflammatory cytokines.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C206.
Abstract C234: A novel microtubule inhibitor BPR0L075 overcomes paclitaxel resistance in ovarian cancer cell lines
Authors: Liu Xinli , Wang Xiaolei , Tedjarati Sean , Wang Tian-Li , Hsieh Hsing-Pang 
Published: June 2012

Abstract
Background: The therapy of choice for women with advanced ovarian cancer involves paclitaxel (Taxol®). However, patients develop resistance to paclitaxel during the course of treatment, which is associated with overexpression of P-glycoprotein and alterations involving class III beta-tubulin. BPR0L075 [6-methoxy-3-(3′,4′,5′-trimethoxy-benzoyl)-1H-indole] is a novel synthetic indole compound that inhibits tubulin polymerization through binding to the colchicines-binding site of tubulin (Kuo et al., Cancer Research , 2004). We investigated the activity of BPR0L075 in highly taxol resistant ovarian cancer cell lines.
Methods: human ovarian cancer cell lines OVCAR-3, SKOV-3, and Taxol resistant subclones OVCAR-3/TR(0.5µM Taxol), SKOV-3/TR(0.25µM Taxol) were used for cytotoxicity and apoptosis evaluations.
Results: BPR0L075 displays potent and broad-spectrum cytotoxic activities at low nanomolar concentrations against parental and drug resistant ovarian cancer cell lines investigated, regardless of the expression levels of the multidrug resistance ABC transporters P-gp and BCRP or class III beta-tubulin. Cell cycle analysis revealed the BPR0L075 induced G2/M cell cycle arrest. Furthermore, western blot analysis shows BPR0L075 treatment increases cyclin B1 levels, cleaves poly(ADP-ribose) polymerase, induces BCl-XL phosphorylation. BPR0L075 may induce apoptosis via a caspase-3 independent mechanism in ovarian cancer cell lines.
Conclusion: The present study shows that BPR0L075 is active in drug resistant ovarian cancer cells, suggesting that BPR0L075 is a promising candidate for development as a novel microtubule therapeutic.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C234.
Abstract C243: B7-H4 protein expression in invasive ductal carcinoma and its association with tumor progression
Authors: Goldberg Allison , Burke Stephanie , Shroyer Kenneth 
Published: June 2012

Abstract
High levels of B7-H4 (DD-O110) protein expression have been previously observed in malignant ductal epithelium of the breast but the mechanisms that mediate B7-H4 up-regulation in tumor progression have not yet been determined. An objective of our research has been to explore the differences in the levels of B7-H4 expression that underlie the transition from benign ductal epithelium to ductal carcinoma in situ (DCIS) and to the earliest stages of invasive ductal carcinoma. B7-H4 is a member of the B7 family of proteins which has been found to play a role in antigen-specific immune response regulation, including the regulation of T cell activation. The potential role of B7-H4 in tumor progression, or in shielding breast cancers from immune surveillance mechanisms, remains relatively unexplored. Previous immunohistochemical (IHC) studies have evaluated only a small subset of available B7-H4 antibody epitopes. The aim of the current study is to determine if there is differential expression of specific B7-H4 epitopes that are associated with benign versus proliferative and malignant breast disease. A panel of monoclonal antibodies to defined B7-H4 epitopes (diaDexus, Inc.) was evaluated in normal breast tissues versus invasive ductal carcinoma, using indirect immunoperoxidase methods, in sections of formalin fixed tissues. The patterns of B7-H4 localization of each antibody were compared with the patterns observed with the previously reported A57.1 antibody (Mugler et al., 2007). B7-H4 IHC scores were determined based on the intensity of staining (0 to 3+), the proportion of positive cells, and the cellular pattern of distribution (apical membranous versus circumferential membranous plus cytoplasmic). Preliminary data suggest that certain B7-H4 epitopes appear to have enhanced cancer selectivity, reflected by differential expression between normal ductal cells versus ductal carcinoma cells. Additionally, these studies confirm that there are differences in the subcellular distribution of B7-H4 expression, with low level, apical membranous expression in benign ductal epithelium and high level circumferential membranous expression in most well to moderately-differentiated ductal carcinomas. Furthermore, there appears to be a marked reduction in the levels of B7-H4 expression in some poorly differentiated carcinomas, despite normal levels of expression in adjacent benign ductal epithelial cells. These results suggest that B7-H4 overexpression may play a role in the progression from benign proliferative disease to low grade carcinomas. Further studies are indicated to refine the association of B7-H4 with tumor histologic grade and stage, and to elucidate the potential role of this protein in shielding breast carcinomas from cell-mediated immune surveillance.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C243.
Abstract C245: Protein switches that activate a prodrug in the presence of HIF-1α
Authors: Wright Chapman M. , Eshleman James R. , Ostermeier Marc 
Published: June 2012

Abstract
We have engineered yeast cytosine deaminase (CD) to be activated by the tumor marker, hypoxia-inducible factor 1-alpha (HIF-1α) - turning on its ability to convert 5-fluorcytosine (5FC) into the anticancer drug 5-fluoruracil (5FU). HIF-1α is overexpressed in many types of cancer but is virtually undetectable in normal tissue due to rapid degradation. We sought a “tumor-sensing” protein whose prodrug converting activity is activated in the presence of HIF-1α. Such a protein could be used in a therapeutic treatment similar to gene-directed enzyme prodrug therapy (GDEPT). However, our approach would have an advantage over GDEPT because the “suicide” gene could be delivered using very efficient methods for gene delivery, whether or not they were selective, since the selectivity occurs at the protein level and not the gene delivery level.
To create our desired protein, we constructed a library of fusion proteins between CD and the CH1 domain of p300 - a domain known to interact with HIF-1α. This library was subjected to a two-tiered genetic selection in E. coli designed to identify genes that conferred increased sensitivity to 5FC when HIF-1α was coexpressed. We identified two library members (#3 and #59), which conferred to E. coli sensitivity to 5FC equivalent to wildtype CD but only in the presence of coexpressed HIF-1α. In the absence of HIF-1α, #3 conferred a 5-fold higher LC50 to 5FC and #59 did not confer any sensitivity to 5FC. Both proteins were purified and characterized in vitro for their activity in the presence and absence of HIF-1a. Protein #3 exhibited a 4-fold increase in its CD activity in the presence of HIF-1α, whereas protein #59's activity did not have a significant dependence on HIF-1α. Currently, the two genes are being examined in human cancer cell lines for their ability to confer sensitivity to 5FC in the presence of HIF-1α.
Using advanced protein engineering techniques, we have created two proteins that confer sensitivity to 5FC in the presence of the tumor-marker, HIF-1α. We believe that these genes have therapeutic potential for the treatment of cancers that exhibit elevated HIF-1α levels. Our strategy circumvents a limitation of GDEPT by not requiring selective delivery of the gene to cancer cells.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C245.