bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B70: Participation of fibroblast growth factor receptors (FGFRs) in acquired resistance to EGFR-specific TKIs in NSCLC.
Authors: Ware Katie E. , Heasley Lynn E.
Published: June 2012

Despite initial and often dramatic responses of specific NSCLC tumors to EGFR TKIs such as gefitinib and erlotinib, nearly all develop resistance and eventually relapse. We have investigated both rapid and chronic mechanisms of resistance to EGFR-specific TKIs in lung cancer cell lines. Following 3 to 4 day treatments with gefitinib, FGFR2 and FGFR3 mRNA and protein are selectively and rapidly (24 to 48 hrs) increased in NSCLC cell lines in which EGFR is the dominant oncogenic driver via mutation or amplification. This induction is mediated, in part, by transcriptional mechanisms and indicates that EGFR signaling functions to repress expression of FGFR2 and FGFR3. Moreover, EGFR TKI-induced FGFR2 and FGFR3 are capable of mediating FGF-stimulated ERK activation and transformed growth in the continued presence of EGFR TKIs. These studies highlight FGFR2 and FGFR3 induction as a rapid molecular response that may modulate initial sensitivity of EGFR-driven lung tumors to EGFR-specific TKIs. We have also employed NSCLC cell lines bearing activating mutations in EGFR and rendered them resistant to EGFR-specific TKIs, gefitinib (reversible) and BIBW2992 (irreversible), through chronic (2–3 months) adaptation in tissue culture. To date, three (HCC4006, H1650, HCC2279) of the eight chronically-adapted NSCLC cell lines exhibit a marked induction of FGF2 and FGFR1 upon acquisition of gefitinib resistance (Table 1). Additionally, two of eight undergo marked loss of epithelial differentiation as measured by decreased E-cadherin. The induction of FGFR1 was not mediated by gene amplification as assessed by FISH analysis. Importantly, these chronically-adapted cell lines were highly sensitive to both FGFR-specific TKIs and an FGF ligand trap, FP-1039, as measured by ERK signaling and growth assays. Thus, induction of FGF2 and FGFR1 following chronic adaptation to EGFR-specific TKIs may provide a novel autocrine receptor tyrosine kinase-driven growth pathway in a subset of lung tumors that were initially sensitive to EGFR-specific TKIs. We are presently exploring the in vivo relevance of this mechanism using primary tumor specimens obtained pretreatment and following tumor progression on EGFR-specific TKIs. Combined, these studies indicate that FGFR-specific TKIs may be valuable additions to existing targeted therapeutic strategies with EGFR-specific TKIs to reduce acquired resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B70.
Abstract B73: Molecular mechanisms of glioma resistance to EGFR tyrosine kinase inhibitors.
Authors: Wykosky Jill E. , Cavenee Webster , Furnari Frank
Published: June 2012

EGFR-targeted therapies such as the tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib have had limited success clinically in glioblastoma (GBM). However, some of the most common mechanisms of resistance to these agents in other solid tumors are rarely present in GBM. In an effort to identify molecular mechanisms of acquired resistance to EGFR TKIs in GBM, we utilized ink4a/arf −/− astrocytes over-expressing EGFR and having wild-type or deleted PTEN. To model TKI-resistance in vitro, cells were seeded in soft agar with 1 μM gefitinib or erlotinib for 2 weeks; during this time the growth of colonies was inhibited. The dose was escalated to 2 μM and after 3 weeks, TKI-resistant colonies began to form and were isolated to generate clonal cell lines. In three PTEN wild-type TKI-resistant lines, EGFR expression was not altered and gefitinib inhibited receptor phosphorylation in a manner identical to that observed in parental cells, thereby ruling out the possibility that the cells are resistant because the drug cannot reach its site of action and inhibit its target. Interestingly, two of these three cell lines demonstrated decreased PTEN expression and increased AKT phosphorylation. The remaining cell line had no change in total PTEN levels, and appeared identical to parental cells with regard to AKT phosphorylation. Removal of resistant cells from the maintenance dose of TKI resulted in restoration of EGFR and ERK phosphorylation to a level several-fold greater than that in parental cells. Notably, the TKI-resistant phenotype was reversible, and these cells became significantly more sensitive to gefitinib and erlotinib than parental cells. Overall, we have generated and characterized a model system for the identification of mechanisms of resistance to EGFR TKIs in GBM. We have identified at least two different resistance scenarios in cells with wild-type PTEN: decrease in PTEN expression, and another as-of-yet unknown mechanism that does not appear to involve changes in the PI3K pathway. The reversibility of resistance and subsequent increased sensitivity to TKIs have potential clinical implications. This work forms the basis for our effort to uncover novel targets or approaches to therapy that may increase the utility of these drugs for treatment of GBM.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B73.
Abstract B8: Selective inhibition of Stat3 Tyr705 phosphorylation inhibits angiogenesis in breast cancer xenografts.
Authors: McMurray John S. , Klostergaard Jim , Robertson Fredika M. , Mandal Pijus K. , Auzenne Edmond J. , Liao Warren S.
Published: June 2012

Signal transducer and activator of transcription 3 (Stat3) is recruited, via its SH2 domain, to phosphotyrosine residues on growth factor and IL-6 family receptors at which time it is phosphorylated on Tyr705 by Janus kinases, Src, or the kinase activity of the receptor. Phosphorylation of Tyr705 (pStat3) leads to dimerization, translocation to the nucleus, and transcription of downstream genes. Stat3 is activated in several human cancers and is considered a drug target. Starting with pTyr-Leu-Pro-Gln, we have been developing phosphopeptide mimics to target the SH2 domain with the goal of blocking recruitment to receptors to uncouple Stat3 from its signaling role. We have developed cell-permeable, phosphatase-stable prodrugs that inhibit constitutive and IL-6-stimulated Tyr705 phosphorylation at concentrations of 0.5 − 1 μM in a variety of human cancer cell lines. They are selective for Stat3 over Stat1, Stat5, Src, and PI3K. At 5 μM they are not cytotoxic to a panel of human cancer cell lines. Higher concentrations lead to off-target effects and cytotoxicity. Recent reports indicate that Ser727 phosphorylated Stat3 participates in electron transfer in the mitochodria and unphosphorylated Stat3 participates with NF-κB-mediated transcription. As opposed to Stat3 knockdown techniques which cannot discriminate the multiple roles of Stat3, our prodrugs are potential tools to selectively probe Stat3 phosphorylation. Both intra-tumoral and intra-peritoneal administration of our lead prodrug, PM-73G, resulted in reduction of orthotopic breast tumor xenografts in mice. There was no evidence of apoptosis, reduction of cyclin D1 or survivin. Treated tumors exhibited significant reduction in microvessel density. Thus, selectively inhibiting Tyr705 phosphorylation is a potential antiangiogenic treatment modality.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B8.
Abstract B9: Evidence that the small molecule antiangiogenic agent PTX008 targets galectin-1.
Authors: Dings Ruud P.M. , Miller Michelle M. , Mayo Kevin H.
Published: June 2012

Inhibition of angiogenesis is a promising avenue for the treatment of cancer in the clinic. Although many or most angiostatic compounds being developed are inhibitors related to various components of growth factor pathways, these have had limited success in the clinic, and new angiostatic compounds that target different systems are sorely needed. Currently, there is growing evidence indicating the importance of galectin-1 in tumor angiogenesis. Galectins are proteins that generally bind β-galactoside-containing glycoconjugates and are involved in various pathological disorders like tumor endothelial cell adhesion, proliferation and migration. Recently, we designed a non-peptidic, calixarene-based galectin-1 antagonist, PTX008, as a relatively small, protein surface topomimetic of the antiangiogenic peptide anginex.

Although we had demonstrated that PTX008 inhibits tumor angiogenesis and tumor growth in vivo, we have yet to confirm that it indeed targets galectin-1. Here, we do just that. By using NMR spectroscopy and flow cytometry, we demonstrate that PTX008 interacts with galectin-1 at a site near to its carbohydrate binding domain and by doing so can compete off galectin-1 from binding to β-galactoside-containing glycans on the surface of cells in vitro. Overall, this research contributes to our ability to design pharmaceutical agents that target galectin-1 and thereby inhibit tumor growth in animals and potentially in the clinic.

This work was supported by a research grant from the NIH National Cancer Institute (CA-096090) to KHM.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B9.
Abstract B91: Assosiation of tumor supressor gene p53 with lung cancer in Pakistani population.
Authors: Munawar Saba
Published: June 2012

Lung cancer is the most common cause of cancer related death in men and second most common in women, after breast cancer. It is known to be responsible for 1.3 million deaths worldwide annually. The p53 gene, is a tumor suppressor gene, i.e. its activity stops the formation of tumors. The gene has been mapped to chromosome 17. In the cell, p53 protein binds DNA, which in turn stimulates another gene to produce a protein called p21 that interacts with a cell division-stimulating protein (cdk2). When p21 is complexed with cdk2 the cell cannot pass through to the next stage of cell division. In present study we check Association of P53 polymorphism with lung cancer in Pakistani population. Polymorphisms in human P53 gene (16bp duplication in intron 3) were studied in patients with lung cancer and controls. Three types of genotypes were seen, homozygous insertion (1\1), homozygous deletion (2\2) and heterozygous insertion/deletion (1/2). Frequency of 1/2 allele was 0.2 in controls and 0.32 in lung cancer patients. This difference is statistically significant (P = 0.053, 95 CI). Our study further showed that smoking increases the risk of lung cancer. Study of polymorphism in p53 gene will help in understanding the patho-physiology of the lung cancer and will open new fronts in future therapeutics.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B91.
Abstract C102: Mitigating the path to destruction: Continuous flow focused resonance nano-permeabilization (CO-FORN) to improve targeted cancer drug delivery.
Authors: Kumar Rajah Vijay , Augustus Meena , Ebner Reinhard , Kumar Ranjit
Published: June 2012

Rotational Field Quantum Magnetic Resonance (RFQMR) is a device-mediated novel therapeutic modality for cancer, currently in the clinical stage of development. It can also be used to deliver an electromagnetic force with strong, embedded, variable radio signals to induce Continuous Flow Focused Resonance Nano-permeabilization or CO-FORN concomitantly with drugs of choice for cancer treatment. Transient permeabilization of cells by Focused Resonance pulses induces a significant increase of anti-tumor drug concentration within the tumor and enables a practical solution to deliver valuable systemic chemotherapy and mitigate associated adverse effects. CO-FORN was administered to a refractory medullobalstoma patient who had previously received metronomic chemotherapy with Cyclophosphamide and VP16, significantly helping to reduce the associated cytotoxicity and myelosuppression commonly accompanying such treatment.

The protocol allows for extremely accurate RFQMR dosing for therapeutic purposes. RFQMR can be applied as an extraneous source to permeate intractable tumors by creating molecular dimension-specific pore sizes. Targeted drug delivery is enabled thereby minimizing associated systemic drug toxicities. It has been shown that electroporation of cultured cells potentiates cytotoxicity of various chemotherapy agents and other targeted molecules by several hundred fold. This potentiation can be highly controlled using RFQMR by adjusting delivery parameters like molecular mass of the drug, peak plasma concentration, total tissue volume, cell membrane characteristics etc. Specific tumors can be resonated with high instantaneous magnetic fields and radio frequency (RF), followed by nano second signals which penetrate only resonating cells.

The CO-FORN technique can potentiate antitumor effectiveness of drugs from 10 to 70 times and can be highly localized and used without implanting any electrodes, probes or particles into the body. Exposure to non-ionizing, non-thermal RFQMR does not cause uncontrollable destruction and entropy within the cell but more likely re-organizes related bio-structures. In principle, depending on the specific variations within the configured RFQMR, a predictable cell response can be expected. The technology allows for extremely accurate RFQMR dosing for therapeutic purposes. Of the several disease indications and applications that the device has been evaluated in extensive R&D efforts at the Center for Advanced Research & Development (CARD) in Bangalore India, the use of RFQMR to permeabilize tumors in conjunction with systemic chemotherapy, is an innovative application.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C102.
Abstract C11: Relationship between GLIPR-1 and c-Myc expression in progression of gastric cancer.
Authors: Kim Jeong Min , Wang Brandon J. , Zhang Xiaglan , Lee Joon Gyo , Kim Tae Soo , Jung Minkyu , Jeung Hei-Cheul , Chung Hyun Cheol , Thompson Timothy C. , Rha Sun Young
Published: June 2012

Glioma Pathogenesis Related-Protein (GLIPR)-1 is up-regulated by p53 and has proapoptotic, antiangiogenic, immunostimulatory and metastasis-suppressing activity in prostate cancer. How ever its expression and biological role is not well known in gastric cancer. Meanwhile, c-Myc overexpression has shown to be related to on the cell growth, proliferation, invasion and cell cycle regulation in gastric cancer. Here, we investigated the expression pattern of GLIPR-1 and its relation with c-Myc expression in gastric cancer.

The protein expressions of GLIPR-1 and c-Myc were evaluated by western blot with whole lysate of 39 gastric cancer cell lines. Band intensities were measured by Image J program. By Immunohistochemisty, we checked the expression of GLIPR-1 in formalin-fixed paraffin-embedded gastric cancer tissues of stage Ito IVwith 20 samples for each stage.

GLIPR-1 was overexpressed in 20 of 39 (51.3%) and c-Myc was overexpressed in 23 of 39 (60%) gastric cancer cell lines. 16 of 39 cell lines (41.1%) had co-expression. Level of GLIPR-1 expression was higher in cell lines established from primary site of gastric cancer (n=13) than the cell lines from metastasis site (n=26) (p < 0.01). On the other hand, c-Myc was overexpressed in the cell lines of metastasis site than primary sites (p<0.01). GLIPR-1 expression of two group cell lines was negatively correlated with c-Myc expression (R = −0.48). In IHC, GLIPR-1 was expressed in nucleus and cytosol of gastric cancer cells, and GLIPR-1 expression was stage-specifically reduced.

This study showed that GLIPR-1 is downregulated while c-Myc is overexpressed in advanced gastric cancer, ssuggestig their associative role in gastric cancer. In addition, as GLIPR-1 is decreased throughout the disease progression. GLIPR-1 might be the specific therapeutic target for advanced gastric cancer. Also, there is the potential to develop GLIPR-1 and c-Myc expression as prognostic biomarker for gastric cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C11.
Abstract C118: Optimization of MM-111 and lapatinib dosing regimens using mathematical modeling and quantitative biology.
Authors: Kirouac Daniel C. , Lahdenranta Johanna , Overland Ryan , Oyama Shinji , Yarar Defne , Onsum Matt , McDonagh Charlotte , Nielson Ulrik
Published: June 2012

Designing therapeutically optimal dosing regimens for targeted biologic therapies is an open problem in translational oncology. There are at least two underlying reasons for this problem: First, biologics are generally well tolerated so it is not guaranteed that the maximum tolerated dose (MTD) will be observed in a Phase 1 dose escalation; and second, since targeted therapies work in only a subset of patients, there will be limited efficacy data available to determine a Phase 2 dose. This problem is further compounded by the use of combination drug treatments. MM-111 is a novel bispecific antibody against ErbB3 (HER3), using an ErbB2 (HER2) targeting arm to enhance avidity and inhibitor potency. Pre-clinical data shows that combining MM-111 with the ErbB2 inhibitor lapatinib (Tykerb®) results in synergistic tumor growth inhibition. We desired to leverage our pre-clinical modeling, signaling, pharmacokinetic (PK), pharmacodynamic (PD), and efficacy data to optimize dosing regimens of the combination therapy. While this study design is focused on MM-111 combined with lapatinib, this strategy is generally applicable to molecular targeted therapeutics given alone or in combination.

Our approach was to integrate a mathematical model of the MM-111 and lapatinib's mechanism of action, incorporating ErbB-family signal transduction, transcriptional regulation, and resulting tumor proliferation, with pre-clinical PK models of the two drugs. This integrated model was trained using in vitro dose response data from BT-474-M3 cells treated with the ErbB3 ligand heregulin plus combinations of the two drugs. Levels of phospho- and total ErbB3, ERbB2, AKT, ERK, and p27 were quantified using ELISA, and cell growth effects quantified using the Cell Titer Glow assay. This was then integrated with a 2-compartment PK-model, to predict PD profiles and tumor growth effects in murine xenografts treated with the drug combinations. After validation of our model with these initial in vivo studies, we designed therapeutically optimal dosing schedules in silico. The novel dosing strategies are now being validated in xenografts, and will help inform future clinical studies. By integrating PK/PD with known molecular mechanisms of action, we are able to rationally design combination treatment strategies to maximize therapeutic synergy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C118.
Abstract C126: Molecular profiling of the HES transcription factor-TLE co-repressor protein-protein interaction site.
Authors: Roffey Jon R. , Hammonds Tim , Raynham Tony , Dillon Christian , Hyde Cali , Pearl Laurence , Ish-Horowicz David
Published: June 2012

Aberrant Notch signalling has been implicated in a variety of tumor types, where it is known to play a role in tumorigenisis and angiogenisis. In particular, recent evidence suggests that the Notch pathway is activated by somatic mutations in a significant proportion of human T cell acute lymphoblastic leukaemias (T-ALLs). Therefore targeting of the Notch pathway represents an attractive avenue for anti-cancer drug discovery. However, apart from the potential use of gamma-secratase inhibitors, there are very few known tractable intervention points along this predominantly protein-protein interaction mediated pathway. The structural characteristics of protein-protein contact surfaces present a huge challenge for small molecule drug discovery as these contact surfaces are generally larger than those involved in protein-small molecule interactions and often lack the grooves and pockets on the protein surface that small molecules efficiently bind to. Recent discoveries in our laboratories indicate that the interaction of the HES transcription factor with the TLE co-repressor could provide a tractable point for small molecule inhibitors that would inhibit the Notch signalling pathway. The interaction between HES/TLE is dependent on a highly conserved contiguous tetra-peptide WRPW motif present in the C-terminus of HES family members which binds to the WD domain of TLE. The binding site on TLE is a potentially druggable hydrophobic recess located at the central pore of a 7-bladed β-propeller structure, and the WRPW motif sits on top of the recess contacting all 7 blades of the -propeller. We have established and validated biochemical fluorescence polarisation (FP) and GST-WRPW pull down assays to identify compounds that disrupt HES/TLE binding in vitro and a GAL4-WRPW reporter luciferase assay was developed as an effective way of monitoring the WRPW dependent interactions between HES and TLE proteins in a cell culture model. Using these assays a small library of peptide derivatives, based around the highly conserved WRPW motif, was screened. SAR from the peptide array in conjunction with structural information from a WRPW peptide bound to TLE1 WD domain was used to construct a 3D pharmacophore model which was applied as a search query for in silico virtual screening.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C126.
Abstract C127: Crystal structure of the SIX1/EYA transcriptional complex reveals ways to inhibit SIX1-mediated breast tumorigenesis/metastasis.
Authors: Patrick Aaron , Cabrera Joshua , Zhao Rui , Ford Heide
Published: June 2012

The Six1 homeoprotein and members of the Eya family of co-activators are thought to form a bipartite transcription factor that is important in development and disease. Six1 and Eya are highly expressed during development, but their expression is lost in most adult tissues. Interestingly, Six1 and Eya are re-expressed in a variety of cancers, where they are known to promote both transformation and metastasis. However, a means to target the complex has remained elusive due to the recognized difficulties in targeting transcription factors. Thus, the molecular details of the protein-protein interface and an understanding of whether complex formation is necessary for tumorigenesis/metastasis are critical to the development of novel anti-cancer therapies targeting the Six1/Eya complex. Here we describe the 1.9 Å resolution crystal structure of the Six1/Eya complex revealing unexpected protein binding interfaces. The interaction resembles that of the p53/HDM2 complex, with a single helix of Six1 binding in a hydrophobic groove in Eya, both distant from sites originally thought to be involved in the Six1/Eya interaction. Remarkably, we show that a single amino acid substitution in Six1, involving a residue in the Eya binding interface, is sufficient to inhibit complex formation and to inhibit properties associated with Six1-induced tumorigenesis/metastasis. Since Six1 and Eya are regulators of embryonic development and are scarcely expressed in adult tissues, inhibition of the Six1/Eya pathway likely will lead to limited side effects in the adult. In addition, since 50–90% of breast cancer patients over-express Six1, therapies targeting the complex are likely to benefit a significant proportion of breast cancer patients, and an even greater proportion of patients with metastatic disease. Together, our findings suggest that inhibiting the Six1-Eya helical interface is a potential mechanism to develop novel, anti-breast cancer agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C127.
Abstract C128: Small-molecule antagonists of MDM2 and MDMX.
Authors: Thompson Thelma , Graves Bradford , Xia Mingxuan , Janson Cheryl , Lukacs Christine , Deo Dayanand , Huang Kuo-Sen , Tovar Christian , Lovey Allen , Wanner Jutta , Vassilev Lyubomir T.
Published: June 2012

The p53 tumor suppressor is controlled by MDM2 and MDMX that negatively modulate its activity. Both proteins possess p53-binding sites within their N-terminal domains and can inhibit the transcriptional activity of p53. However, only MDM2 can serve as E3 ubiquitin ligase for p53 and is thus responsible for its stability. MDMX does not have intrinsic ligase activity but can modulate the ligase activity of MDM2. Many human tumors overproduce MDM2 or MDMX to impair p53 function. Small-molecule MDM2 antagonists, the nutlins, interact specifically with the p53-binding pocket of MDM2 and can release p53 from negative control. Treatment of cancer cells expressing wild-type p53 with nutlins stabilizes p53 and activates the p53 pathway, leading to cell cycle arrest and apoptosis in vitro and in vivo. However, nutlins and other published MDM2 antagonists do not inhibit the p53-MDMX interaction and their effectiveness can be compromised in tumors overexpressing MDMX. We identify the first small molecules that potently block p53 interaction with both MDM2 and MDMX (in vitro IC50 of 17 nM and 24 nM, respectively) by inhibitor-driven homo- and/or hetero-dimerization of MDM2 and MDMX proteins. Structural studies revealed that these idole-hydantoin compounds bind into and occlude p53 pockets of MDM2 and/or MDMX by inducing the formation of dimeric protein complexes kept together by a dimeric small-molecule core. This novel mode of inhibiting protein-protein interactions effectively stabilized p53 and activated p53 signaling in cancer cells, leading to cell cycle arrest and apoptosis.

MDM2/MDMX antagonist, RO-5963, restored p53 apoptotic activity in cultured osteosarcoma cells in the presence of high levels of MDMX. RO-5963 showed a significantly better apoptotic activity against MCF7 and other solid tumor cell lines with higher MDMX levels than the MDM2-specific inhibitor, nutlin-3a, suggesting that dual antagonists may offer a more effective therapeutic modality for MDMX-overexpressing cancers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C128.
Abstract C135: Therapeutic targets for MYC-driven cancer.
Authors: Toyoshima Masafumi , Howie Heather , Imakura Maki , Walsh Ryan , Park Julie , Grandori Carla
Published: June 2012

Drugs directed toward oncoproteins have demonstrated efficacy while avoiding the systemic toxicity associated with standard chemotherapeutics. However, oncoproteins encoding for transcription factors, such as the MYC family, which are broadly implicated in many human cancers, are difficult to inhibit with small molecules or antibody based therapies. Thus, to target MYC-driven cancers, we have taken the approach of identifying druggable genes that exhibit a synthetic lethal relationship with aberrant MYC expression. Using an isogenic cell model system, we identified, via high throughput siRNA screening, more than 100 druggable genes that exhibit a synthetic lethal interaction with MYC (referred to as MYC-synthetic lethal genes, MYC-SL). Among the MYC-SL genes, we focused on casein kinase 1 epsilon (CSNK1e), whose relevance in MYC-driven human cancer was demonstrated by correlation between high levels of CSNK1e expression, MYCN amplification, and poor clinical prognosis in neuroblastoma cases. The requirement of CSNK1e for growth of neuroblastomas with MYCN amplification was validated in vivo by conditional knock-down and via a small molecule inhibitor of its activity. CSNK1e had previously been implicated in the regulation of WNT, however our data also suggest that in neuroblastoma the activity of CSNK1e is a key component of a positive autocrine circuit triggered by MYCN amplification that sustains both WNT and SHH pathways. In summary, our work elucidates a broad network of MYC synthetic lethal genes, perhaps a reflection of its widespread effects on gene expression, and demonstrates the power of high throughput siRNA screening as a rapid and unbiased approach to identify a network of synthetic lethal genes and potential new therapeutic targets functionally linked to a previously un-druggable oncogene.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C135.
Abstract C147: Itraconazole side-chain analogs reveal a distinct structure-activity relationship for inhibition of hedgehog pathway signaling.
Authors: Aftab Blake T. , Shi Wei , Nacev Benjamin A. , Head Sarah , Liu Jun O. , Rudin Charles M.
Published: June 2012

Itraconazole is an antifungal drug that was recently found to potently inhibit the Hedgehog (Hh) signaling pathway. The mechanism of inhibition of Hh signaling is distinct from that of cyclopamine-competitive inhibitors currently in late-stage clinical development. Itraconazole has also been described as a potent inhibitor of activation of vascular endothelial growth factor receptor-2 (VEGFR-2) and tumor associated angiogenesis. The unexpected activities associated with this FDA-approved agent offer a unique opportunity for expansion of its use to the oncology arena. As such, itraconazole is currently being evaluated in several clinical trials targeting proliferative disease, including basal cell carcinoma and recurrent metastatic non-small cell lung cancer. To date, the target(s) of itraconazole responsible for these activities remain to be determined. In these studies we expand the characterization of the activity profile for itraconazole by examining potency in the context of a Smoothened receptor point-mutation associated with clinical resistance to vismodegib (GDC-0449). Additionally, in the interest of understanding the structure-activity relationship (SAR) guiding Hh pathway targeting and working towards the identification and development of inhibitors demonstrating greater potency and specificity; twenty-five itraconazole side chain analogs were synthesized and assayed for inhibition of Hh pathway activation. Furthermore, the SAR associated with the inhibition of phospho-activatable forms of VEGFR2 is also described. Through these analyses we report that itraconazole maintains potency against the Hh pathway in the context of the D477G Smoothened mutation (mouse homologue to human D473H). We also conclude that SAR trends for targeting of the Hh pathway are divergent from those associated with inhibition of VEGFR2 signaling. Taken together, these results suggest that modification of the sec-butyl side chain of itraconazole can enhance compound activity and differentially affects inhibition of the Hh pathway and VEGFR2 signaling.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C147.
Abstract C149: STAT3 is a critical mediator of the prosurvival effect of Bcl-2-Rac1 interaction in human cancer cells.
Authors: Kang Jia , Vali Shireen , Kapoor Shweta , Abbasi Taher , Pervaiz Shazib
Published: June 2012

The small GTPase Rac1 is involved in the activation of the reduced NAD phosphate oxidase complex resulting in superoxide production. We recently showed that Bcl-2 overexpression inhibited apoptosis by creating a pro-oxidant intracellular milieu, and that inhibiting intracellular superoxide production sensitized Bcl-2-overexpressing cells to apoptotic stimuli. Gene silencing and functional inhibition of Rac1 blocked Bcl-2-mediated increase in intracellular superoxide levels in tumor cells. We provide evidence for a co-localization and physical interaction between the 2 proteins, which could be blocked in vitro and in vivo by the BH3 mimetics as well as by synthetic Bcl-2 BH3 domain peptides. That this interaction is functionally relevant is supported by the ability of the Bcl-2 BH3peptide as well as the silencing and functional inhibition of Rac1 to inhibit intracellular superoxide production as well as overcome Bcl-2-mediated drug resistance in human leukemia and cervical cancer cells. Notably, the interaction was observed in primary cells derived from patients with B-cell lymphoma overexpressing Bcl-2 but not in noncancerous tissue. In an attempt to study the functional implication of this interaction, we carried out a computer simulation driven virtual predictive experiments based on the protein pathway dynamic network created by Cellworks Group Inc. The base line used for the study was a KRAS over-activated, PI3K overexpressed, CDKN2A deleted, β-catenin overexpressed and Bcl-2 overexpressed system aligned to HCT116 human colorectal cancer cell line. When a variant of the above base line was created with Rac1 overexpression, phenotypic indices of angiogenesis, proliferation, viability, metastasis as well as tumor volume were all upregulated. Strikingly, the expression levels of STAT3 and β-catenin were significantly amplified in the computer modeled variant cell line; however upon Rac1 or Bcl-2 knockdown in both the base and the variant cell lines, apoptotic markers such as Bax, caspase 3 and cleaved PARP1 were increased while STAT3, β-catenin, NF-κB and AGER were significantly down-regulated. Intrigued by these predictions, we set out to verify the link between STAT3 signaling and Bcl-2-Rac1 interaction. Interestingly, the activation status of STAT3 (pY705) strongly correlated with Bcl-2 expression as well as Rac1 activation status. Furthermore, STAT3 was found localized to mitochondria and preliminary results suggest an interaction with Bcl-2.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C149.
Abstract C15: Combined blockade of AKT kinase with gemcitabine overcomes FKBP5-mediated resistance of inhibition of pancreatic tumor growth.
Authors: Hou Junmei , Wang Liewei
Published: June 2012

We have recently showed that the immunophilin FKBP5 (also known as FKBP5) as a scaffolding protein that can enhance PHLPP-AKT interaction and facilitate PHLPP-mediated dephosphorylation of AKT-Ser473, negatively regulating AKT activation in vitro. Therefore, FKBP5 might function as a tumor suppressor and levels of FKBP5 would affect cell response to chemotherapy. In the current study, we took a step forward by using pancreatic caner xenograft mice model to show that FKBP5−/− promotes tumor growth and renders resistance to gemcitabine and addition of AKT inhibitors have more significant sensitization effect on FKBP5−/− mice to gemcitabine treatment. The combination of triciribine and gemcitabine resulted in cooperative inhibition of pancreatic cancer cell proliferation and the growth of xenografts in vivo without increasing toxicity, as well as cooperative inhibition of AKT signaling pathways at concentrations that were ineffective as individual agents. These results provide evidence for future clinical studies designed to tailor the therapy based on the biomarker.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C15.
Abstract C154: microRNA and targets in the poor prognosis of ovarian cancer patients.
Authors: Cui Shiying , Zhao Henan , Ding Yanfang , Zhao Jinyao , Bi Tie , Jiang Jiyong
Published: June 2012

Epithelial ovarian cancer (EOC) is the most important cause of gynecologic malignancy-related mortality in women. Ovarian clear cell carcinoma (CC) has a poor survival rates and ovarian papillary serous carcinoma (PSC) has a high incidence in the EOC. To get the insight of possible regulator and pathway that may involved in the EOC prognosis and progress, patient samples of CC, PSC and normal ovarian or oviduct tissues were employed in the study. Total 48 human tumor samples and 6 normal ovarian and oviduct tissues were obtained from the patients who were surgically treated for ovarian cancer or other disease at the Obstetrics and Gynecology Hospital, Dalian China. The tissue was further fixed by formalin and embedded by paraffin as routine. Total RNA that enriched miRNAs was extracted from the FFPE tissue by using the Ambion mirVana microRNA isolation kit (Ambion, Austin TX). The quality of total RNA was assessed using the Agilent Bioanalyzer (Agilent Technologies, Santa Clara CA). Quantitative Real-Time polymerase chain reaction (qRT-PCR) assays were formatted into a TaqMan low-density array (TLDA; Applied Biosystems), which was performed at the Shannon McCormack Advanced Molecular Diagnostics Laboratory Research Services, Dana Farber Cancer Institute, Harvard Clinic and Translational Science Center. The normalized microarray data were managed and analyzed by Statminer version 3.0. The targets of miRNA were predicted by using computational approaches, the MicroCosmTargets version 5 and miRBase. The pathway was analyzed by commercial available Ingenuity software. Finally the target predicted was validated by qRT-PCR and imunohistochemistry.

The results showed that 101 miRNAs are differentially expressed in the patients of CC compared with PSC, of which 86 (85%) miRNAs were down-regulated in CC patients, suggesting a majority of regulators in the poor prognosis of CC are tumor suppressors. The key miRNAs that were down-expressed in CC patients are miR-9, miR-202, miR-488, miR-509–5p and up-expressed are miR-217, and miR-550. Hundred of gene targets and protein target on the pathways were predicted, but the top targets are enhancer of polycomb homolog 1 (EPC1) and mycophyta (c-MYC), which were validated by qRT-PCR assay at mRNA level and confirmed by immunohistochemistry at molecules level.

We identified the key miRNAs that differentially expressed in patients of CC and PSC tumors, predicted and validated the most popular targets regulated by the key miRNAs, indicating the possible regulation gene and pathway for EOC prognosis.

This work was supported by the Ministry of Science and Technology of China, Program No. 2008DFA30720 to Shiying Cui.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C154.
Abstract C155: Inhibition of TAK1 promotes apoptosis in KRAS and Wnt pathway codependent colon cancers.
Authors: Singh Anurag , Sweeney Michael F. , Settleman Jeff , Haber Daniel A.
Published: June 2012

Colorectal cancers frequently harbor KRAS mutations but KRAS-mutant cancers are refractory to conventional and targeted therapeutics. The primary aim of this study was to identify novel therapeutic strategies to target KRAS-mutant colon cancers. Firstly, we found that a subset of KRAS-mutant colorectal cancer cell lines are dependent upon KRAS signaling for survival. Secondly, we found that KRAS-dependent colorectal cancer cells require the TAK1 kinase (MAP3K7) for sustained viability. TAK1 depletion or the small molecule TAK1 kinase inhibitor 5Z-7-oxozeaenol results in profound apoptotic cell death in KRAS-dependent cells. Lastly, we noted that sensitivity to TAK1 disruption is associated with enhanced Wnt signaling resulting from APC mutations combined with KRAS hyperactivation. This effect can be attributed in part to a KRAS-mediated activation of BMP signaling, leading to TAK1 activation. TAK1 then directly regulates Wnt signaling specifically in KRAS-dependent cells. In primary human colorectal cancers, expression of a gene signature derived from TAK1-dependent cell lines is correlated with APC and KRAS mutational status. Thus, our studies reveal TAK1 inhibition as a potential therapeutic strategy for the generally treatment-refractory subset of colorectal cancers that are driven by the KRAS and Wnt pathways.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C155.
Abstract C156: GRB7 is required for triple-negative breast cancer motility, invasion, and chemoresistance.
Authors: Giricz Orsi , Calvo Veronica , Pero Stephanie C. , Krag David N. , Sparano Joseph A. , Kenny Paraic A.
Published: June 2012

Triple-negative breast tumors lack expression of estrogen and progesterone receptors and HER2, rendering them non-responsive to the most effective targeted therapies in breast cancer. These tumors are typically more aggressive than other breast cancer subtypes and, consequently, have a poor prognosis. In a clinical trial of triple-negative breast cancer patients treated with anthracyclines and taxanes, we and others have recently determined that high levels of GRB7 are predictive of tumor recurrence (Sparano et al. J Clin Oncol 27(15s) 500). GRB7 is a cytoplasmic adaptor protein that interacts with receptor tyrosine kinases and integrins, transducing information to their downstream signaling cascades.

In this study, we have tested the hypothesis that triple-negative breast cancer cell lines are dependent on GRB7 for migration, invasion and colony formation in 3D culture. Using a highly specific peptide inhibitor (G7–18NATE), we found that the GRB7 inhibition significantly impaired each of these phenotypes in four triple-negative breast cancer cell lines: MDA-MB-468, MDA-MB-231, HCC70 and T4-2. In addition, we have tested whether GRB7 inhibition may sensitize these cell lines to the chemotherapies used in the initial clinical trial. Combination treatment with G7–18NATE and doxorubicin or docetaxel resulted in cooperative cell growth inhibition in each of the four cell lines. Co-treatment lowered the IC40 of both chemotherapeutic agents, and it proved to be synergistic in all cases (Combination Index values <1)

These data implicate GRB7 as a key mediator of migration, invasion, colony growth and chemoresistance of triple-negative breast cancer cells and suggest that GRB7 itself, or GRB7-dependent pathways, may prove to be important therapeutic targets.

This work was supported in part by Susan G. Komen for the Cure (KG091136 and KG100888).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C156.
Abstract C157: Identification of activated receptor tyrosine kinases in colon cancer cell lines.
Authors: Lee Choong-kun , Lee Myung Eun , Hong Soojung , Kim Han Sang , Kim Hye Ryun , Shin Yoo Kun , Kim Tae Soo , Ahn Joong Bae , Chung Hyun Cheol , Rha Sun Young
Published: June 2012

Colorectal cancer (CRC) is the second most common cause of cancer-related death in the United States and increasing rapidly in Asian countries. To improve colorectal cancer treatment, relevant molecular targets need to be identified. Receptor tyrosine kinases (RTKs) are multifunctional transmembrane proteins and important mediators of the signaling cascade, determining key roles in diverse biological processes such as proliferation, growth, differentiation, and apoptosis of cells. Recent advances in understanding of cellular signaling by RTKs have brought to light the potential of RTKs as anti-cancer targets. To determine if any of these RTKs are activated in colorectal cancer, we performed phospho-receptor tyrosine kinase array and evaluated its possibility as a therapeutic target. We examined activation pattern of RTKs in 10 colon cancer cell lines using Human Phospho-RTK Antibody Proteome Profiler Array (R&D Systems). Relative levels of tyrosine phosphorylation of RTKs among these cell lines were determined as a ratio relative to positive control's intensity in each membrane. TKI-258 (Novartis Inc.), a specific class III-V RTK inhibitor, was used to evaluate its anti-cancer effect. To confirm of anti-cancer effect of TKI-258 in vivo, xenograft model with LoVo cells was used. We found that various RTKs including fibroblast growth factor receptor (FGFR), vascular endothelial growth factor receptor (VEGFR) and platelet-derived growth factor receptor (PDGFR) were highly activated in colon cancer cell lines. The RTK activity and related signaling molecules were decreased on TKI-258 treatment in a time-dependent manner. Also, TKI-258 treated cells showed significantly impaired anchorage-independent growth in soft agar colony formation assay as compared with the control cells. In vivo xenograft model, TKI-258 treated group showed anti-tumor growth effect compared with control group. These results suggested that various RTKs are highly activated in colorectal cancer, and these RTKs might be specific targets for colorectal cancer treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C157.