bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A148: Targeting cholesterol pathway genes sensitizes cancer cells to EGFR inhibitors.
Authors: Gorin Andrey
Published: June 2012

EGFR signaling is one of the main mechanisms of providing cancer cell growth. Although blockade of this pathway is among the most widely used therapies in cancer, only 10% of patients show positive response to it. There is an unmet need in the clinic to improve the efficacy of anti-EGFR drugs.

We recently conducted siRNA screening and identified the sterol biosynthesis pathway enzymes as synergistic co-targets that strongly sensitize cells to EGFR inhibitors (Astsaturov et al., 2010). SC4MOL (sterol C4-methyl oxidase-like) and NSDHL (NADP-dependent steroid dehydrogenase-like) work in complex and catalyze the C4-demethylation step of cholesterol biosynthesis. We have found that depleting either of these enzymes sensitizes cancer cell lines to anti-EGFR therapy. Blockade of upstream and downstream enzymes of the cholesterol pathway do not cause such effect. Moreover depletion of upstream enzyme CYP51A1 abrogates the effect of SC4MOL and NSDHL blockade to response of cancer cells to EGFR inhibitors. Bioinformatic search of the evolutionarily conserved protein interactions of SC4MOL and NSDHL orthologs showed multiple connections with proteins regulating vesicular trafficking.

We postulated that blockade of sterol biosynthesis pathway at the C4-demethylating level alters regular EGFR traffic towards its degradation. We observed that loss of SC4MOL and NSDHL leads to profound loss of EGFR and its family members ErbB2 and ErbB3 and to distortion of receptor distribution inside the cells. In evidence skin keratinocytes of mosaic NSDHL-deficient Bpa1H/+ mice appeared to have reduced EGFR level comparing to normal skin.

Altogether, these data indicate that SC4MOL and NSDHL are related to trafficking of EGFR in cells that finally leads to its degradation. And, inasmuch as this receptor is one of the most usable targets in anti-cancer therapy, the blockade of these enzymes can be potentially used to prevent the resistance to EGFR inhibitors and thereby increase the efficacy of anti-EGFR therapy.

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 A148.
Abstract A157: Targeting MYC dependence in cancer by inhibiting BET bromodomains.
Authors: Sims Robert
Published: June 2012

The MYC transcription factor is a master regulator of diverse cellular functions and has long been considered a compelling therapeutic target because of its role in a wide range of human malignancies. However, pharmacologic inhibition of MYC function has proven challenging due to both the diverse mechanisms driving its aberrant expression and the challenge of disrupting protein-DNA interactions. Here we demonstrate the rapid and potent abrogation of MYC gene transcription by representative small molecule inhibitors of the BET family of chromatin adaptors. MYC transcriptional suppression was observed in a variety of genetic contexts. Inhibition of BET bromodomain-promoter interactions and subsequent reduction of MYC transcript and protein levels resulted in G1 arrest and extensive apoptosis in a variety of cell lines. Genetic reconstitution experiments indicate that MYC predominantly mediates the phenotypes observed with BET inhibition. MYC suppression was also accompanied by deregulation of the MYC transcriptome. Treatment with a BET inhibitor resulted in significant anti-tumor activity in lymphoma and leukemia xenograft models. These findings demonstrate that pharmacologic inhibition of MYC is achievable through targeting BET bromodomains. Such inhibitors may have clinical utility given the widespread pathogenetic role of MYC in 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 A157.
Abstract A162: Targeting chromatin: Small molecules reactivating H3K27me3 silenced genes.
Authors: Chapman-Rothe Nadine , Shamsaei Elham , Cherblanc Fanny , Ganesh Thota , Snyder James P. , Fuchter Matthew J. , Brown Robert
Published: June 2012

There is a need for the development of compounds allowing more targeted and efficient reversal of aberrant epigenetic silencing in cancer. Recently, the discovery of histone lysine methyltransferases (HKMT) being involved in tumorgenesis as well as tumor stem cell like maintenance has sparked interest in this particular class of enzymes. We have set-up a cell based assay (MDA-MB-231) in order to identify small molecule inhibitors which are able to re-express endogenous genes where EZH2 has been shown to be involved in the silencing process. In order to identify compounds which inhibit a specific chromatin remodeler class (silencing of chromatin), we chose two DNA unmethylated EZH2 target genes (KRT17, FBXO32), which we would be expect to be re-expressed and one DNA methylated EZH2 target gene (RUNX3) which we would expect to be unaffected in case of an HKMT inhibitor. SiRNA to EZH2 increases expression of KRT17 and FBXO32, but not RUNX3. We have assayed compounds chemically related to a known HKMT inhibitor and identified compounds that up-regulate KRT17 as well as FBXO32 but fail to act on RUNX3. These compounds inhibit tumor cell growth in the low microMolar range. Chromatin immunoprecipitation (ChIP) experiments verified a decrease in silencing marks (H3K27me3, H3K9me3) and importantly an increase in active chromatin marks (e.g. H3K4me2, H3K4me3) at the promoter region of KRT17 and FBXO32. Of note, the H3K27me3 demethylase JMJD3 also showed increased binding at the promoter region which correlated with the presence of H3K4me2/3. In conclusion, we have identified compounds that induce re-expression of genes, reverse H3K27me3 mediated gene silencing and induce inhibition of tumor cell growth.

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 A162.
Abstract A167: First-in-patient study of PF-05212384, a small molecule intravenous dual inhibitor of PI3K and mTOR in patients with advanced cancer: Update on safety, efficacy, and pharmacology.
Authors: Millham Robert , Houk Brett , Borzillo Gary , Tabernero Josep , Bell-McGuinn Katherine , Bendell Johanna , Molina Julian , Kwak Eunice , Shapiro Geoffrey
Published: June 2012

Background: Activation of the PI3K pathway, by PIK3CA mutation or amplification or PTEN deletion, has been implicated in a wide variety of human cancers. PF-05212384 is a dual-specificity inhibitor of PI3K and mTOR that is formulated for intravenous (IV) administration. PF-05213384 is the first IV PI3K/mTOR inhibitor to be tested in a clinical trial.

Methods: In this ongoing phase 1 trial, PF-05212384 was administered once weekly, using a modified continual reassessment method (CRM) for estimation of the maximum tolerated dose (MTD). Assessments included safety (NCI CTC AE v4.0), pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity (RECIST v1.1). PD assessments included blood glucose and immunohistochemistry analysis of phosphoprotein biomarkers in tumor and surrogate tissue (hair follicles). The population was actively enriched for patients with dysregulation in the PI3K pathway.

Results: As of 15 March 2011, 47 patients have been enrolled at doses ranging from 10 mg to 319 mg. Median age was 58. Represented tumor types included CRC (8), NSCLC (4), ovarian/endometrial/cervical (8), salivary (3) and gastric/esophageal (3). Analysis of archived tumor biopsies revealed PI3K pathway alterations in 12/26 evaluable patients; alterations included PTEN loss, PIK3CA mutation or amplification. PF-05212384 was well tolerated with the most common AEs being mucositis (44%), nausea (42%), fatigue (28%), rash (28%), and hyperglycemia (26%). DLTs included mucositis, rash, transaminase elevation, and hyperglycemia. An MTD of 154 mg weekly has been estimated. PF-05212384 is eliminated with a half-life of approximately 16 hours, with low clearance (5–9 L/h) and relatively high volume of distribution (54–144 L). Changes in blood glucose have been observed in 13 patients, including 2 patients with Grade 3 hyperglycemia, a known effect of PI3K/Akt pathway suppression. No objective tumor response has been observed; 12 patients have achieved stable disease (SD) in excess of 16 weeks, with 9 patients on study for ≥24 weeks and one patient (salivary) on study for >46 weeks. Enrollment to MTD expansion cohorts is ongoing.

Conclusions: Weekly administration of PF-05212384 is safe and tolerable across dose levels with multiple patients deriving clinical benefit with prolonged SD. The occurrence of hyperglycemia is suggestive of target modulation. Updated data for safety, PK, PD and antitumor activity will be presented

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 A167.
Abstract A17: Mode of action of trabectedin in myxoid liposarcomas.
Authors: Giandomenico Silvana Di , Frapolli Roberta , Bello Ezia , Pilotti Silvana , Casali Paolo , Grosso Federica , Sanfilippo Roberta , Gronchi Alessandro , Galmarini Carlos , D'Incalci Maurizio
Published: June 2012

Background: Trabectedin (ET-743, Yondelis) is a marine alkaloid isolated from the tunicate Ecteinascidia turbinata, cytotoxic against a variety of tumor cell lines in vitro and human tumor xenografts in vivo. It has been approved by EMEA for the 2nd line therapy of soft tissue sarcomas in 2007 and for the 2nd line therapy of ovarian cancer in 2009. Myxoid liposarcoma (MLS) is a specific histological subtype within the family of adults soft tissue sarcomas. Specifically >90% of usual myxoid/round cell liposarcomas (MLS/RCLS) are characterized by the chromosomal translocation t(12;16) (q13;p11), which produces the FUS-CHOP oncogene. Different variants of the fusion gene have been previously described but with no demonstrable prognostic effect although the type III MLS seem correlate with a more severe outcome than type II MLS.

Materials and Methods: To elucidate the mechanisms behind the differential sensitivity to trabectedin, myxoid liposarcomas type II and type III were xenografted in nude mice. When tumor load achieves about 200–400 mg mice were divided into the experimental groups. Trabectedin was administered at 0.15 mg/kg, i.v. every 7 days for three times. Tumor growth was monitored by Vernier caliper. The binding of FUS-CHOP to some of its target promoters was monitored by Chromatin Immuno Precipitation (ChIP) to verify the drug ability to displace the binding. ChIP were performed with ProtG Sepharose and the anti-FUS and anti-CHOP antibody. The immunoprecipitated DNAs were analyzed by quantitative Real Time PCR. FN1, PTX3, CDK4, IL8 and CHOP were used as target genes.

Results: We found that trabectedin was more effective on type II than type III MLS xenografts. The response to trabectedin in type II xenografts was associated with partial regression and pathological response. Type III MLS xenografts appeared much less sensitive to trabectedin and tumors did not regress. Molecular analysis revealed that trabectedin was able to remove FUS-CHOP type II and III from its own target genes 24 hours after treatment. 72 hours after treatment, FUS-CHOP Type III was attached to its targets whereas FUS-CHOP Type II remained unbound. These data explain why in order to achieve a significant regression of type III MLS xenografts a more prolonged treatment with trabectedin is required.

Conclusions: These results suggest that the different sensitivity of type II and type III MLS to trabectedin are related to a different duration of the drug ability to display FUS-CHOP from the selected target genes.

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 A17.
Abstract A183: Whole-genome sequencing to find potential targets for therapy in patients with refractory K-ras mutated metastatic colorectal cancer.
Authors: Ramanathan Ramesh K. , Shanmugam Viji , Sinari Shripad , Chadha Manpreet , Liang Winnie , Izatt Tyler , Christoforides Alexis , Benson Hollie , Phillips Lori , Baker Angela , Hostetter Galen , Von Hoff Daniel , Craig David , Carpten John
Published: June 2012

Introduction: The outcome of patients with metastatic colorectal carcinoma (mCRC) following first line therapy, especially with a K-ras mutation is poor with median survival of less than one year. The purpose of this study was to perform whole genome sequencing (WGS) to identify therapeutically actionable somatic events in mCRC patient samples, so as to select targeted treatment strategies for individual patients.

Methods: IRB approval was obtained and 3 patients have been enrolled. All had > 2 prior regimens and had known K-ras mutations (age 73, 45 and 50 years, all were male). Percutaneous needle biopsies of liver metastases were performed with whole blood collection for the extraction of constitutional DNA. WGS was performed using Illumina paired end chemistry on HiSeq2000 sequencing system, which yielded coverage of greater than 30X for both the normal and tumor samples. Somatic genomic alterations (point mutations and indels, copy number alterations, translocations and rearrangements) were analyzed using our custom pipeline for paired analysis.

Results: In all 3 samples sufficient DNA was extracted for sequencing. WGS and bioinformatics analysis took 3–4 weeks for completion. We found that all 3 tumor samples had KRAS mutations, while 2 samples had mutations in the APC gene and the PIK3CA gene. Other genes with therapeutic implications in single tumor samples were INPPL1, INPP4B and SMAD4. No EGFR amplifications were detected in our sample set. The concomitant mutations in MAPK (K-ras) and PI3K (PIK3CA, INPPL1, INPP4B) pathways suggest that combination therapies might be required for effective treatment of these tumors. In two instances, tumors were sent to a CLIA laboratory to allow for clinical validation of genomic events.

Conclusions: WGS is feasible from DNA obtained from percutaneous biopsies in a clinical setting. Our study has revealed a series of therapeutically actionable events in mCRC and prospective clinical trials are needed to validate this approach.

Funded by the Bisgrove-Scottsdale Healthcare and TGEN foundations.

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 A183.
Abstract A186: KIF14 is a novel therapeutic target for ovarian cancer.
Authors: Theriault Brigitte L. , Pajovic Sanja , Bernardini Marcus Q. , Shaw Patricia A. , Lim Harvey , Gallie Brenda L. , Gallie Brenda L. , Bernardini Marcus Q.
Published: June 2012

Introduction: The dismal prognosis associated with ovarian cancers (OvCa) is a consequence of late detection and ineffective strategies to prevent progression. Hence, identification and targeting of genetic events underlying OvCa tumor initiation and progression may have greater potential to achieve cure. Our study of the paediatric eye cancer retinoblastoma revealed mechanisms of cancer initiation and development, where progression is associated with specific genomic aberrations shared among multiple cancers. We identified the novel oncogene KIF14 (kinesin family member 14, chromosome 1q31–1q32), gained in many cancers including retinoblastoma, lung, breast, and ovarian. We demonstrated that KIF14 overexpression in breast and lung cancers is predictive of poor outcome. In normal cells, KIF14 acts during cytokinesis to ensure proper cell division, however its mechanism of action in cancer cells is unknown. Knowledge of the biology of KIF14 in OvCa may therefore define an important therapeutic target.

We hypothesize that KIF14 overexpression contributes to OvCa tumorigenesis.

Results: Real-time QPCR analysis of primary OvCa tumors demonstrated that KIF14 mRNA is overexpressed in the majority of OvCa tumors studied (111 out of 122 samples), regardless of histological subtype. Close to 30% of serous OvCas display genomic gain of KIF14, with similar gains in early and late stages, suggesting that gain of KIF14 could be an early event in the development of serous OvCa. Multivariate Cox regression analyzes revealed that KIF14 mRNA levels were independently predictive of poor outcome and increased rates of recurrence in serous OvCa patients, demonstrating the value of KIF14 expression as a potential marker for “high risk” serous OvCa patients. Stable in vitro overexpression of KIF14 in OvCa cells increased proliferation and soft agar colony formation, while stable shRNA knockdown of KIF14 decreased proliferation and dramatically reduced soft agar colony formation. In vivo tumor formation is also dependent on KIF14 expression, as KIF14 knockdown significantly reduced subcutaneous xenograft formation by 20-fold. These findings demonstrate the transformed phenotype is dependent on KIF14.

Conclusions: KIF14 expression is tumor-specific, can predict poor prognosis, and OvCa cells depend on KIF14 for maintenance of the transformed phenotype. Thus KIF14 overexpression is an oncogenic stimulus in OvCa, pointing to the potential utility of KIF14 expression as a prognostic biomarker, and KIF14 knockdown as a novel therapy to slow or halt OvCa progression.

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 A186.
Abstract A188: MET inhibition by SU11274 impairs proliferation, motility, and invasion in hepatocellular and cholangiocarcinomas.
Authors: Tijeras-Raballand Annemilai , Serrate Camille , Riveiro Maria Eugenia , Serova Maria , Guedj Nathalie , Bieche Ivan , Paradis Valerie , Raymond Eric , Faivre Sandrine
Published: June 2012

Background: Hepatocellular carcinomas (HCC) and cholangiocarcinomas (CK) are the most common primary tumors of the liver and are recognized among the most difficult tumors to treat. Signaling mediated by hepatocyte growth factor (HGF)/MET promotes multiple biological activities, including cell proliferation, motility, invasion, angiogenesis, and morphogenesis. Advanced HCC and CK are often displaying aberrant MET signaling and MET overexpression was observed in many tumors resistant to tyrosine kinase inhibitors (TKI). The aim of present study was to evaluate the effects of MET inhibition by SU11274 on HCC and CK cell proliferation and invasion.

Materials and Methods: SU11274 is a pyrrole indolinone that specifically inhibits overexpressed and oncogenic MET activation at nanomolar concentrations. MET expression was assessed on human paraffin-embedded liver section by immunohistochemistry. Antiproliferative effects of SU11274, were evaluated in human HCC (SK-Hep1 and its sunitinib-tolerant counterpart SK-Suni) and CK (Mz-chA-1, Mz-chA-2, SK-ch) cell lines using a MTT assay. mRNA expression and protein levels were respectively assessed by qRT-PCR and Western blot. Cell mobility was investigated by wound-healing and matrigel invasion assays.

Results: Higher MET protein expression was observed in human HCC and CK samples respect to normal tissues. MET-protein and -mRNA expression were detectable in all tested cell lines, Mz-ChA-1 and Mz-ChA-2 expressing higher MET levels. HGF-induced MET activation was associated with increase of p-METTyr1234/35, p-GAB1, p-ERK1/2, and p-AKTser473 in SK-CH, Mz-chA-2, SK-Hep1 and SK-Suni cells. We show that SU11274 inhibited HGF-induced downstream signaling by reducing p-METTyr1234/35, p-GAB1, p-AKT473 and p-ERK1/2 in HCC and CK cells at concentrations ranging from 0.5 to 2μM. However, antiproliferative effects were only observed for concentration above 2 μM (2,5 and 5 μM), In SK-Suni cells that are tolerant to high dose of sunitinib, proliferation was not inhibited even at the higher SU11274 dose (5μM). Interestingly, SU11274 potently decreased the spontaneous and HGF-dependent cell motility and invasion of Mz-chA-2 cells.

Conclusion: In HCC and CK cells, inhibition of MET-signaling by SU11274 resulted in inhibition of cell proliferation, motility and invasion. HCC and CK may be interesting tumor types to evaluate novel MET inhibitors either as single agents and/or in combination with other targeted therapies.

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 A188.
Abstract A190: Effect of anti-VEGF acute treatment on tumor uptake of trastuzumab in a xenograft model.
Authors: Pastuskovas Cinthia V. , Boswell C. Andrew , Mundo Eduardo E. , Williams Simon P. , Tibbitts Jay , Khawli Leslie A.
Published: June 2012

Overexpression of both human epidermal growth factor receptor 2 (HER-2/neu) and vascular endothelial growth factor (VEGF) are associated with aggressive disease and decreased survival among breast cancer patients. Accordingly, the combination of bevacizumab (anti-VEGF) with trastuzumab (anti-HER2) has demonstrated promising results in both preclinical and clinical studies. However, little is known about anti-VEGF antibody's effects on the disposition and pharmacokinetics of other antibodies. This study assessed the biodistribution of trastuzumab in the presence or absence of an anti-VEGF antibody, with a particular emphasis on tumor uptake. Mice bearing HER2 expressing KPL-4 breast cancer xenografts received trastuzumab or a non-HER2 binding antibody radiolabeled with either 125I or 111In to assess the real time kinetics and cumulative tumor uptake with and without pre-administration of an anti-VEGF antibody. Acute anti-VEGF treatment reduced tumor uptake of trastuzumab. This effect was consistently observed by tissue distribution, autoradiography, and SPECT-CT imaging despite comparable blood exposures and similar distributions in most other tissues. A similar trend was also observed for an isotype-matched IgG with no affinity for HER2. Reduced tumor blood flow was observed following anti-VEGF treatment, and immunohistochemistry showed evidence of reduced vascular density. In conclusion, anti-VEGF pre-administration resulted in decreased tumor uptake of trastuzumab, and this phenomenon may be explained, at least in part, by reduced vascular permeability and blood flow. These findings add to the current understanding of combination anti-HER2/anti-VEGF therapy and may ultimately lead to improved clinical outcomes.

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 A190.
Abstract A191: The application of three-dimensional cell cultures in combination with the Virtual Tumor for designing optimal drug dosing schedules.
Authors: Brightman Frances , Fernandez Eric , Orrell David , Fell David , Chassagnole Christophe
Published: June 2012

There is currently a great deal of interest in determining synergistic drug combinations, however, it is not easy to determine which schedules should be tested, since the number of different possible schedules increases combinatorially when more than one drug is considered. We have therefore developed a predictive PK-PD “Virtual Tumor” model that allows rational design of schedules for drug combinations. We previously built a Virtual Tumor that was capable of successfully simulating the outcome of various drug combination schedules in xenografts; using this model we were also able to propose new optimal administration schemas. Although xenografts represent a convenient and relatively inexpensive approach to assessing the likely efficacy of proposed dosing regimens in vivo, the number of permutations that can be tested is still limited by practical considerations. We have therefore explored the use of three-dimensional tumor cell cultures (microtissues) as a more cost-effective alternative to xenografts for validating Virtual Tumor predictions. Here we present a microtissue Virtual Tumor that is analogous to our xenograft model, and a comparison of the utility of each in simulating and optimising drug dosing schedules. The application of microtissues in combination with the Virtual Tumor technology can be used to design new regimens with proprietary compounds as well as standards of care, small molecules or biotherapeutical agents; help test possible schedules for combinations of different drugs that would be effectively impossible to investigate experimentally; and allow prioritisation of the most effective drug combinations.

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 A191.
Abstract A206: Chk1 protects normal cells from HDAC inhibitor-induced cell death.
Authors: Lee Ju-Hee , Choy Megan L. , Ngo Lang , Venta-Perez Gisela , Marks Paul A.
Published: June 2012

Histone deacetylase inhibitors (HDACi) are a new class of selective anti-cancer agents that inhibit zinc-dependent histone deacetylases. HDACi in clinical trials have shown anti-cancer activity at well-tolerated doses. The mechanisms of resistance to HDACi are important in developing these agents for cancer therapy. We previously showed that vorinostat induces DNA damage in both transformed and normal cells. Normal cells can repair the DNA damage, while transformed cells cannot and undergo apoptosis and death. This study found Chk1, a component of the G2 checkpoint, protects normal cells from HDACi-induced cell death. Culture with HDAC inhibitor plus Chk1 inhibitor (UCN-01, AZD7762 or CHIR124) killed normal cells, while there was no cell death in culture of normal cells with HDAC inhibitor alone. Chk1 inhibitor also increased cell death of transformed cells cultured with HDACi. In culture with both HDACi and Chk1 inhibitor, mitotic abnormalities which included loss of sister chromatid cohesion and chromosomal disruption were observed in normal and transformed cells. These findings show that intact Chk1 is important for the resistence of normal cells to HDACi and suggest that combined treatment of HDACi with Chk1 inhibitor may cause substantial toxicity.

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 A206.
Abstract A214: F14512, a novel targeted cytotoxic agent exhibits a marked antileukemic activity, alone and in combination with AraC.
Authors: Kruczynski Anna , Pillon Arnaud , Creancier Laurent , Vandenberghe Isabelle , Gomes Bruno , Annereau Jean-Philippe , Fournier Emmanuel , Sarry Jean-Emmanuel , Demur Cécile , Delabesse Eric , Pourtau Sandrine , Cartron Valérie , Marty Fabien , Roy Sabine , Chansard Nathalie , Blanchet Jean-Christophe , Verdier Jérôme , Ricome Christel , Offrete Vanessa , Gras Stéphane , Guminski Yves , Recher Christian , Bailly Christian , Guilbaud Nicolas
Published: June 2012

Chemotherapy remains mainly used for the treatment of Acute Myelogenous Leukemia (AML). However, in the past 3 decades limited progress has been achieved in improving the long-term disease-free survival. Therefore the development of more effective drugs for AML represents a high level of priority. F14512 combines an epipodophyllotoxin core targeting topoisomerase II with a spermine moiety introduced as a cell delivery vector. In fact the polyamine moiety facilitates F14512 selective uptake by tumor cells via the polyamine transport system, a machinery frequently overactivated in cancer cells. In this study, we report the in vivo antileukemic activity of F14512 against human AML models, established from patient samples. AML cells, collected from 3 different patients, were established onto NSG mice (LAM-2, LAM-7 and LAM-18). These 3 AML samples exhibited a normal karyotype, with FLT3-ITD, NPM1 and DNMTA3 mutations which proved stable over serial transplantations in vivo. After multiple i.v. administrations of F14512, 3 times a week for 3 weeks, an extensive reduction of AML cell number (98–99%) was observed in LAM-2 and LAM-7 - bearing mice. This antileukemic activity was recorded on the basis of flow cytometry, q-PCR and histology assessments. The effects of F14512 on LAM-18 bearing mice were marginal with an inhibition of AML cell growth of 42%. We also show in vitro and in vivo synergistic effects of F14512 in combination with AraC, one of the frontline chemotherapeutic agents for AML. These results were obtained using the HL-60 cell line. The activity of F14512 in combination with AraC will be further investigated in patient AML models. Collectively, these results demonstrate that F14512 exhibits a marked in vivo antileukemic activity, supporting its clinical development. Phase I clinical trials in onco-hematology are on going with this novel promising drug candidate.

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 A214.
Abstract A217: The HSP90 inhibitor AT13387 demonstrates potent antitumor activity in both imatinib-sensitive and imatinib-resistant gastrointestinal stromal tumor models.
Authors: Smyth Tomoko , Van Looy Thomas , Curry Jayne , Wozniak Agnieszka , Rodriguez-Lopez Ana , Schoffski Patrick , Lyons John , Thompson Neil , Wallis Nicola
Published: June 2012

Background: Activating mutations in the receptor tyrosine kinase, KIT, are found in the majority of gastrointestinal stromal tumors (GIST) and further secondary resistance mutations in KIT frequently arise upon treatment with tyrosine kinase inhibitors such as imatinib. KIT and its mutant forms are sensitive clients of HSP90 and it has been suggested that HSP90 inhibition could be an effective treatment for both imatinib-sensitive and imatinib-resistant GIST, which can occur simultaneously in different clones within the same patient.

Methods: AT13387 is a fragment-derived, potent HSP90 inhibitor, which is currently being evaluated in clinical trials. To evaluate its anti-tumor activity against GIST, AT13387 was tested in both imatinib-sensitive (GIST882, GIST-PSW) and imatinib-resistant (GIST430, GIST48) in vitro and in vivo GIST models.

Results: AT13387 inhibited the proliferation of GIST cell lines at sub-100 nM potencies, irrespective of their sensitivity to imatinib. Treatment of GIST882, GIST430 and GIST48 cells with AT13387 induced HSP70, a marker of HSP90 inhibition, whilst reducing the levels of the client proteins KIT, AKT and their phosphorylated forms. A concomitant decrease in the levels of phospho-ERK and phospho-S6 demonstrated that KIT signaling was being inhibited in all cell lines, whilst an increase in cleaved PARP indicated apoptosis. In contrast, treatment with imatinib inhibited KIT signaling only in the imatinib-sensitive line, GIST882.

In vivo, the efficacy of AT13387 was tested in imatinib-sensitive (GIST-PSW) and imatinib-resistant (GIST430) xenograft models. AT13387, dosed once a week, inhibited the growth of both xenografts; depletion of phospho-KIT and inhibition of KIT signaling were again seen in these tumors. As expected, treatment with imatinib caused significant regression of the GIST-PSW tumors but not of GIST430. The combination of imatinib and AT13387 significantly enhanced tumor growth inhibition (T/C 21%) over either of the monotherapies (T/C 30% for AT13387, 46% for imatinib) in the GIST430 xenograft. Importantly, the combination was well tolerated.

Conclusions: AT13387 is currently being evaluated in a Phase II GIST trial both as single agent and in combination with imatinib. These results support the potential efficacy of the compound in both imatinib-sensitive and imatinib-resistant GIST and its current testing in this disease.

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 A217.
Abstract A220: The efficacy of varying concentrations of intravesical apaziquone on murine bladder cancer in an animal model.
Authors: Reddy Guru , Denes Bela , Kovacs G.
Published: June 2012

Introduction and Objectives: Apaziquone is a novel bioreductive alkylating agent in development for intravesical therapy of nonmuscle invasive bladder cancer. The standard dose of apaziquone in all ongoing clinical studies is 4 mg/ 40 mL (0.1mg/mL). The objective of this study was to test the efficacy of varying concentrations of apaziquone versus placebo in an animal model of bladder cancer.

Methods: A total of 1×105 MB49 cells were instilled into the bladder of C57BL/6 mice after electrocauterization to establish the tumor model. Mice bearing orthotopic tumors were administered varying concentrations of apaziquone (0.05, 0.1, 0.4, and 0.8 mg/mL) or placebo (0.85% saline) via intravesical instillation (0.1 mL) one week after tumor implantation. Instillations were continued once a week for 4 weeks. Tumor incidence, overall and median survival is reported.

Results: At the end of the observation period (80 days), all animals in the control (0.85% saline) and 0.05 mg/mL groups had died (fig. 1). The median survival of mice receiving apaziquone at concentrations of 0.1 mg/mL (42.5 days); 0.4 mg/mL (40.5 days) and 0.8 mg/mL (49 days) was longer than that of mice treated with 0.05 mg/mL (30 days) and 0.85% saline (27 days). Statistically significant differences in survival were observed in control vs apaziquone-treated groups [0.1 mg/ml(P < 0.05); 0.4 mg/mL(P < 0.01); 0.8 mg/mL (P < 0.01)], and in the low concentration (0.05 mg/mL) vs 0.1 mg/mL (P < 0.05), 0.4 mg/mL (P < 0.01) and 0.8 mg/mL (P < 0.01), respectively.

The median survival of the 0.1, 0.4 and 0.8 mg/mL treated groups did not differ, but 33.3% in the 0.1 mg/mL cohort, and 14.3% in the 0.4 mg/mL cohort were long-term survivors (>80 days). All other animals (n = 37) had died of cancer by the end of the observation period. Three mice did not survive anesthesia. At necropsy all mice had advanced local disease with deep invasion of the muscularis propria, and usually with multiple lung metastases.

Conclusion: Apaziquone at the 0.1 mg/mL concentration demonstrates excellent antitumor activity compared to placebo or 0.05 mg/mL solutions. In this model there was no significant difference in the median survival between 0.1 mg/mL and higher concentrations of apaziquone (0.4 and 0.8 mg/mL) supporting continued development with the current clinical dose (0.1mg/mL).

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 A220.
Abstract A237: Elevated Mnk kinase activity is associated with malignant progression and reduced patient survival in human prostate cancer and can be therapeutically inhibited in human prostate cancer cells by the novel, orally bioavailable Mnk inhibitor cercosporamide.
Authors: Konicek Bruce , Hall Chad , Dumstorf Chad , Colligan Bruce , Dong Sucai , Na Songqing , Deddens James , Douglass Larry , Carter Julia , Graff Jeremy R.
Published: June 2012

In a wide variety of malignancies, progressive disease and reduced patient survival have been linked to increased function of eukaryotic translation initiation factor 4E (eIF4E), which selectively enhances the translation of potent growth and survival factors and oncoproteins (e.g. c-myc, VEGF, cyclin D1, Mcl-1, MMP-9, etc.). Recent published reports have shown that the oncogenic activity of eIF4E is critically dependent on the activity of the MNK kinases (Map kinase interacting kinase 1 and 2), which phosphorylate eIF4E at S209 (p4ES209). Increased p4ES209 has been linked to a variety of advanced cancers, notably head and neck and non-small cell lung cancers. Herein, we report that p4ES209 is significantly elevated in human prostate cancer (CaP) tissues (n=133) and associated with reduced patient survival. p4ES209 is elevated In both low grade (Gleason score ≤ 6) and high grade (Gleason score ≥ 7) CaP vs. adjacent normal prostate tissue (BPH) (p < 0.02 and p < 0.0001, respectively). Elevated p4ES209 in invasive CaP is related to significantly reduced patient survival (p = 0.0216) and increased risk of death from CaP (hazard ratio = 2.729). Moreover, p4ES209 is evident in the LNCaP, LNAI, CWR22Rv1 CaP cell lines, with levels being highest in the castrate-resistant cells (LNAI and CWR22Rv1). shRNA-mediated knock-down of MNK 1 and 2 reduced p4ES209 levels and specifically triggered apoptosis. Similarly, treatment of these cell lines with the novel, orally-bioavailable MNK inhibitor, cercosporamide, reduced p4ES209 in a dose-dependent manner and induced apoptosis coincident with reduced expression of key translationally controlled proteins (e.g. Mcl-1). Further, oral administration of this inhibitor can suppress p4ES209 in normal mouse tissues and in xenografted human cancers within 30 minutes, lasting at least 4 hours in tumor tissue. These data demonstrate the utility of cercosporamide in probing MNK function in vitro and in vivo and highlight the potential utility of targeting MNK for prostate cancer therapy.

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 A237.
Abstract A242: A novel AKT inhibitor, PH427, prevents UVB-induced signaling in human squamous skin carcinomas.
Authors: Meuillet Emmanuelle J. , Mash Eugene A. , Olsen Erik , Moses Sylvestor A. , Morgan Sherif S.
Published: June 2012

Non-melanoma skin cancers (NMSC) are a significant and increasing health problem in the United States that occur primarily on sun-exposed areas of the body and are strongly associated with chronic sun exposure. Recent advances in our understanding of the molecular basis of carcinogenesis have lead to the identification of potential molecular targets that might be used to prevent the progression of early skin cancer. AKT (protein kinase B), a pleckstrin homology (PH) lipid binding domain and a serine/threonine kinase containing protein is a key component of the phophatidylinositol-3-kinase (PtdIns3-K) cell survival signaling pathway which is activated in skin cancers. In this study, we describe the effects of a novel inhibitor of AKT (PH427) that binds to the PH domain of AKT thus preventing its binding to PtIns-(3,4,5)P3 at the plasma membrane and subsequent activation. PH427 inhibits AKT activity at low micromolar concentrations in HaCat human keratinocytes and HaCat-II,4, a ras transformed human keratinocyte cell line. We demonstrate that PH427 is able to prevent UVB-induced AKT activation and expression in both cell lines. PH427 also induced apoptosis in both HaCat and HaCat II,4 keratinocytes. Moreover, the compound is lipophilic and penetrates the skin in SKH-1 mice when applied topically. Short term in vitro studies showed that PH427 prevents UVB-induced AKT activation and UVB-induced signaling, as measured by p70S6 Kinase and p-GSK3-activation. Long-term in vivo studies utilizing SKH-1 mice have also shown significant reduction of UVB-induced skin tumors when PH427 is topically applied when compared to acetone-only control or PH427 alone. Additionally, drug treated mice exhibit reduced levels of phospho-Ser473AKT in the epidermal layers. We conclude that the topical application of PH427 may be beneficial for preventing NMSC.

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 A242.
Abstract A27: The combination of navitoclax and PLX4720 in melanoma in vitro and in vivo.
Authors: Hoff Taylor , Cho Daniel , Panka David , Sepehr Alireza , Curtis Lauren , Mier James W. , Sullivan Ryan J.
Published: June 2012

Introduction: Approximately 40–50% of patients with melanoma have a tumor which harbors a BRAF mutation (BRAF+). Vemurafenib is a highly selective inhibitor of mutant BRAF which has recently been FDA-approved for the treatment of patients with BRAF+ advanced melanoma. While response rates to vemurafenib are high, the vast majority of patients will develop resistance. Identification of therapeutic strategies to enhance the efficacy of vemurafenib is a high priority. Navitoclax is a BH3-only mimetic which has single agent activity in tumors with low Mcl-1 and enhances the toxicity of agents which inhibit or downregulate MCL-1. As recent data suggests that selective BRAF inhibitors inactivate Mcl-1 through upregulation of BIM, we therefore studied the effects of combining PLX4720, a selective BRAF inhibitor very similar to vemurafenib, with navitoclax in vitro and in vivo.

Methods: Three BRAF mutant melanoma cell lines (A2058, A375, SKMel5) were selected for in vitro analysis and treated for 6 hours with DMSO, navitoclax (1 uM), PLX4720 (1 uM), or the combination. Cells were then lysed after 6 hours of treatment and western blot analysis was performed probing for vinculin, PARP, total and phosphorylated Erk, Mcl-1, BIM, BID, AKT, pS6, and NOXA. Xenografts were generated from the A375 and A2058 cell lines in nude beige mice and grown to 10 mm in size. Mice were then treated with vehicle, navitoclax (100 mg/kg/day), PLX4720 (100 mg/kg/day), or the combination once daily by gavage for 14 days. Tumor measurements were taken daily.

Results: Treatment of melanoma cell lines with PLX4720 resulted in downmodulation of Mcl-1 and induction of BIM both in vitro and in vivo. In vitro, the combination of navitoclax and PLX4720 led to greater PARP cleavage than either agent alone. In vivo, the navitoclax enhanced the efficacy of PLX4720 in both xenograft models. Interestingly, the two xenograft models showed differential sensitivity to treatment with the respective single agents.

Conclusion: The combination of a selective BRAF inhibitor with a BH3-mimetic may be a promising therapeutic strategy to enhance the clinical efficacy of BRAF inhibitors. Efforts are underway to assess such a combination clinically.

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 A27.
Abstract A30: Inhibition of PMCA4 as a strategy to increase the effectiveness of Bcl-2 inhibitor-mediated cell death in breast cancer cells.
Authors: Roberts-Thomson Sarah J. , Curry Merril C. , Luk Nicole A. , Monteith Gregory R.
Published: June 2012

Intracellular calcium is a vital cell signaling molecule that can influence a myriad of important cellular functions, including those deregulated in the cancer cell. Consequently Ca2+ levels within the cell must be precisely controlled. Amongst the suite of proteins controlling calcium homeostasis are the plasma membrane calcium ATPases (PMCAs), which belong to a family of druggable proteins. PMCAs are pumps that reside on the plasma membrane and are responsible for the efflux of intracellular Ca2+ and thus are important in maintaining basal cellular calcium levels. Sustained increases in intracellular Ca2+ can be a trigger for cell death and agents that induce alterations in calcium signaling could be a strategy to restore the sensitivity of a cancer cell to death stimuli. The aim of this study was to explore the effectiveness of inhibiting two PMCA isoforms, PMCA1 and PMCA4, on the augmentation of cell death initiated by a Ca2+ionophore (ionomycin) and a Bcl-2 inhibitor (ABT-263) in MDA-MB-231 breast cancer cells. Ionomycin represents a caspase-independent mechanism of cell death and ABT-263 enhances cell death via a caspase-dependent mechanism. PMCA1 and PMCA4 were inhibited using siRNA and the effect on cell death was measured by staining with Hoechst 33342 and propidium iodide using high content imaging (ImageXpress). Intracellular Ca2+ was determined using a FLIPRTETRA with cells loaded with the calcium sensor Fluo4-AM. Inhibition of PMCA1 was associated with significant changes in global cytosolic free Ca2+ induced by purinergic receptor activation, whereas the same effect was not seen with PMCA4 inhibition. Consistent with effects on global calcium levels, ionomycin (3 μM)-induced cell death was significantly augmented by PMCA1 but not PMCA4 siRNA. However, ABT-263 (3 μM)-induced cell death was augmented only by inhibition of PMCA4, suggesting that PMCA4 siRNA-mediated inhibition of ABT-263 apoptosis is mediated through effects on local and/or specific calcium signaling processes. PMCA4 can alter the activity of calcium-dependent transcription factors in cardiac myocytes independent of global cytosolic calcium. In MDA-MB-231 cells, the effects of PMCA4 inhibition appear to be associated with alterations in the activity of NFkappaB. These results highlight the specificity of different isoforms of PMCA in the modulation of cell death pathways in MDA-MB-231 breast cancer cells. Inhibition of PMCA4 may be a viable adjuvant therapy when combined with Bcl-2 family inhibitors for the treatment of breast 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 A30.