bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A69: Subtype-specific targeting of RAS signal transduction in pancreatic ductal adenocarcinoma.
Authors: Mirzoeva Olga K. , Collisson Eric A. , Schaefer Peter M. , Roy Ritu , Korn W. Michael
Published: June 2012

Pancreatic ductal adenocarcinoma (PDA), the fourth-leading cause of cancer related death in the US, remains an incurable disease. Among the most promising targets for new treatments for PDA is the KRAS oncogene since mutations in this gene are found in about 90% of all cases. Because attempts to target the KRAS protein itself have failed so far, inhibiting pathways down-stream of KRAS in particular the MAPK and PI3K pathways, represent promising targets. We discovered that inhibition of MEK, a major effector of KRAS signaling, leads to feedback activation of the pro-survival PI3K/AKT pathway through an EGFR-mediated mechanism. In agreement with this finding, many PDA cell lines show synergistic growth inhibition and induction of apoptosis when treated with combinations of MEK and EGFR inhibitors or MEK with PI3K inhibitors. We profiled gene expression patterns in an extensive panel of human PDAC cell lines and identified two subtypes with epithelial and mesenchymal features, respectively. The vast majority of cell lines demonstrating synergism in response to combinations of MEK inhibitors (CI1040 or PD0325901) with EGFR inhibitors (erlotinib) were of epithelial sub-type. In contrast, none of the mesenchymal-type PDA lines showed synergistic effects with respect to apoptosis or cell growth inhibition. Predictor analysis using the cell line mRNA expression data revealed a 13-gene signature predictive of sensitivity to the drug combination. We hypothesize that these predictors will allow for the development of patient selection strategies for clinical application of combinations of MEK- and EGFR inhibitors in PDA.

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 A69.
Abstract A7: The heparan sulfate mimetic PG545 as a monotherapy or in combination with the standard-of-care agents paclitaxel or carboplatin inhibits solid tumor progression in two murine models of ovarian cancer.
Authors: Dredge Keith S. , Hammond Edward , Handley Paul , Rowley Jessica , Peart Melissa , Brandt Ralf , Bytheway Ian
Published: June 2012

PG545 is a fully synthetic heparan sulfate (HS) mimetic currently being assessed by subcutaneous administration in Phase I clinical trials for advanced cancer patients. PG545 inhibits the enzymatic activity of heparanase, angiogenesis, solid tumor growth and spontaneous metastases in different tumor types. As a role for tumor angiogenesis emerged in the development of ovarian cancer, the number the clinical investigations using avascular therapies have increased in recent years. Moreover, given the fact that ovarian cancers can metastasize by multiple routes, the dual antiangiogenic and antimetastatic activity of PG545 may offer a promising approach to treat ovarian cancer patients. Standard treatment with PG545 involved a loading and maintenance dosing regimen of 20 mg/kg followed by weekly injections of 10 mg/kg as previously reported. In these studies the antitumor effect of weekly dosing with PG545, both as a monotherapy and in combination with standard-of-care agents, was investigated. In the first study, mice bearing A2780 tumors were treated with PG545 alone, paclitaxel alone (15 mg/kg, qw) or in combination of both compounds. Treatment with PG545 reduced tumor growth (TGI = 42%) compared to vehicle control and was more effective than paclitaxel alone (TGI = 11%). In combination, PG545 and paclitaxel significantly reduced tumor volume (TGI = 61%) compared to vehicle control. In a second model, mice bearing SKOV3 tumors received PG545, carboplatin (60 mg/kg) or in combination. Treatment with PG545 significantly inhibited tumor growth (TGI = 40%) compared to vehicle control, almost equivalent to the effect of carboplatin monotherapy (TGI = 41%). The combination regimen further impacted tumor growth, showing a significant effect by day 19 of treatment (TGI = 71% versus the vehicle control and the monotherapy groups). In conclusion, PG545 demonstrates antitumor activity as a monotherapy in ovarian cancer models which can be substantially enhanced using combination regimens with current standard-of-care agents such as paclitaxel and carboplatin.

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 A7.
Abstract A80: Modified dosing schedules with the EGFr inhibitors gefitinib and lapatinib in rodent models of mammary and urinary bladder cancer: Preventive and therapeutic effects.
Authors: Lubet Ronald , Bode Ann , Szabo Eva , Grubbs Clinton J.
Published: June 2012

The EGFR inhibitors are approved for treatment of lung and pancreatic cancers (Erlotinib, Gefitinib) and Neu overexpressing breast cancer (Lapatinib) in humans; as well as preventing multiple cancers in animal models. However, the development of toxicities (Iressa, skin rashes; Lapatinib, diarrhea) limit their potential use in prevention; and perhaps even in an adjuvant setting. We examined whether alternative dosing regimens which might reduce toxicity would still achieve preventive and therapeutic efficacy. Female Sprague-Dawley rats were administered a single IV dose of methylnitrosourea (MNU) at 50 days of age. In a prevention study, MNU treated rats administered Gefitinib daily (10 mg/kg BW/day, 7×/week) or Gefitinib (70 mg/kg BW, 1×/week) beginning 5 days after MNU resulted in 94 and 75% reductions, respectively, in cancer multiplicity. Simultaneous measurements of tumor load (number of tumors × tumor weight) showed that both regimens resulted in greater than a 90% decrease. In the therapeutic study (initiating treatment when animals developed a small palpable cancer), both regimens were again highly effective. A prevention study was also performed with Lapatinib (75 mg/kg BW/day, 7×/week or 525 mg/kg BW, 1×/week). While the daily dose reduced cancer multiplicity 90%, the weekly dose caused a 70% reduction. Finally, we examined the effects of daily or weekly dosing with Iressa (100 mg/kg BW/day, 5×/week or 500 or 250 mg/kg BW, 1×/week) in an ER− mouse model (using MMTV/Neu; p53+/− mice). This study showed that while daily dosing with Iressa decreased tumor multiplicity approximately 80%, weekly dosing at either dose caused roughly a 50% decrease. These data show that even a significant alteration in the dosing of Gefitinib (EGFR 1) or Lapatinib (EGFR 2/1) still resulted in a large reduction in mammary cancers. We similarly tested Lapatinib (weekly, 525 mg; or daily, 75 mg/kg/day) in a delayed preventive/therapeutic setting in an OH-BBN model of urinary bladder cancer. We found that although daily dosing was most effective weekly dosing was still relatively effective. The important clinical question will be whether this altered dosing will diminish the toxicities associated with these agents. We cannot determine this in animal models since, at the effective doses employed, the typical toxicities observed in humans are not observed. Supported by NCI contract number HHSN261200433001C.

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 A80.
Abstract B108: The novel HDAC inhibitor PCI-24781 synergizes with tamoxifen in ER-positive breast cancer by concertedly downregulating AKT1 expression.
Authors: Thomas Scott , Raha Paromita , Thurn K. Ted , Chen Stephanie , Munster Pamela
Published: June 2012

Breast cancer continues to be the most frequently diagnosed malignancy in women, and is second only to lung cancer as the cause of cancer death. While aromatase inhibitors are more commonly used in postmenopausal women, tamoxifen remains the only approved hormonal therapy for premenopausal patients presenting with estrogen receptor (ER)-positive disease. However, the effectiveness of tamoxifen is limited, as many tumors develop resistance. As such, substantial effort has been made to improve and extend the effectiveness of tamoxifen. To this end, we have demonstrated that histone deacetylase (HDAC) inhibitors potentiate the anti-tumor activity of tamoxifen in preclinical models, and in an early phase trial durable responses were achieved in a heavily pre-treated patient cohort. Mechanistic studies have revealed that HDAC inhibition directs breast cancer cells into mitochondrial-mediated apoptosis in part by altering the balance of apoptotic gatekeepers (e.g. Bax, Bak, and Bcl-2). In the current study, we extend our mechanistic understanding of this combination in ER-positive cells using the novel hydroxamic acid type HDAC inhibitor PCI-24781. Early clinical evaluation suggests that PCI-24781 is a potent HDAC inhibitor and is well tolerated at doses exceeding those needed for preclinical synergy. Here we demonstrate that PCI-24781 and tamoxifen act individually to additively abrogate AKT cell signaling by down regulating AKT1 mRNA and protein expression. Furthermore, PCI-24781 represses ESR1 transcription and thus exerts its effect on AKT1 expression in part through the regulation of ER expression. Attenuated AKT signaling manifests in elevated GSK3α/β phosphorylation, Bim, and p21 and a reduction in cyclin D. Cells exhibit an induction of an array of pro-apoptotic drivers, mitochondrial release of cytochrome C, caspase activation, and cell death. These results suggest that HDACs regulate the response of AKT to tamoxifen and that the cooperative effects of HDAC inhibitors and tamoxifen lead to enhance cell death. Therefore, early introduction of an HDAC inhibitor into hormonal therapy in patients with ER-positive breast cancer may counter the emergence of tamoxifen 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 B108.
Abstract B139: Arginine deprivation with pegylated arginine deiminase regulates key metabolic genes in RNA and DNA synthesis in ASS1-deficient malignant mesothelioma cells: Clinical implications.
Authors: Delage Barbara , Luong Phuong , Phillips Melissa , Chmielewska-Kassassir Malgorzata , Cutts Rosalind , Chelala Claude , Ghazaly Essam , Jithesh P. V. , Fennell Dean , Lemoine Nicholas R. , Hawkes Geoffrey , Wozniak Lucyna , Joel Simon , Jackson Robert C. , Szlosarek Peter W.
Published: June 2012

Tumors deficient in argininosuccinate synthetase-1 (ASS1), a key enzyme involved in arginine synthesis, are auxotrophic for arginine and sensitive to amino acid deprivation. Currently, several trials are testing the arginine-depleting agent, pegylated arginine deiminase (ADI-PEG20) in patients with cancer, including a randomised phase II multicenter UK study in patients with ASS1-deficient mesothelioma (NCT01279967). Here, we sought to identify key pathways involved in the mechanism of action of ADI-PEG20 using a panel of ASS1-deficient malignant mesothelioma (MPM) cell lines as our model. Epithelioid (2591), biphasic (MSTO) and sarcomatoid (JU77) mesothelioma cells were exposed to ADI-PEG20 and analysed using Affymetrix gene expression profiling with validation of candidate genes by qPCR and western blotting, and metabolic studies by LC-MS and 1H-NMR. ADI-PEG20 modulated several metabolic genes involved in nucleotide synthesis in the MPM cell lines. We identified suppression of ribonucleotide reductase (M1 and M2 isoforms), thymidylate synthase and dihydrofolate reductase by 24hrs, the latter enzymes being known targets of pemetrexed, a multitargeted antifolate used in the first-line therapy of mesothelioma. Moreover, metabolic profiling revealed upregulation of several modified nucleosides, including ribothymidine and downregulation of the nucleotide, guanosine monophosphate. Lastly, in vitro studies confirmed potentiation between ADI-PEG20 and pemetrexed and sequential therapy led to reduced tumor growth in vivo. In conclusion, arginine depletion modulates several key enzymes involved in nucleotide synthesis, providing a rationale for combining ADI-PEG20 with pemetrexed-containing regimens in the clinic.

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 B139.
Abstract B173: Inhibition of the Mdm2-p53 interaction by geraniin.
Authors: Tatsuda Daisuke , Iijima Masatomi , Kitayama Takashi , Momose Isao , Nomoto Akio
Published: June 2012

Damage by UV, IR, chemical agents and other stresses causes cell cycle arrest and induces DNA repair in eukaryotic cells while severe DNA damage invokes apoptosis. Cell cycle checkpoint signaling pathways are responsible for cell cycle arrest and decisions about cell survival or apoptosis. Because the cell cycle checkpoint signaling pathway also regulates cell survival and apoptosis in tumor cells, proteins related to this pathway are attractive targets for anti-tumor drugs. p53 is a transcription factor and participates in cell cycle checkpoint signaling pathways. Mdm2 has ubiquitin E3 ligase activity and binds to p53 to promote its degradation by the ubiquitin-proteasome pathway. Inhibition of this Mdm2-p53 interaction induces cell cycle arrest and apoptosis. To search for new anti-tumor compounds, we constructed an Mdm2-p53 interaction assay using the in vitro TR-FRET technique to screen for natural products that inhibit this interaction. Using TR-FRET, we found that geraniin from plant extracts inhibited the Mdm2-p53 interaction. This inhibition was stronger than that induced by the microorganism product altenusin (IC50 58 nM and 2100 nM for geraniin and altenusin, respectively). A luciferase reporter assay showed that geraniin induced activation of p53 transcriptional activity in colon cancer cells. Geraniin also increased protein expression levels of p53 and inhibited cell growth in glioblastoma cells.

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 B173.
Abstract B18: Champions Tumorgraft™ models demonstrate spontaneous metastases.
Authors: Albee Lee D. , Friedman Jay , Anderson Nathan , James Meredith , Bruckheimer Elizabeth M.
Published: June 2012

One of the challenges in oncology drug development is the lack of in vivo models that demonstrate the spontaneous metastatic process. Standard subcutaneous implantation of cell-line based xenografts models seldom results in the generation of spontaneous metastatic lesions. In general, experimental metastatic models are utilized which requires the intravenous injection of cells or orthotopic implantation of tumors cells to replicate metastases. These methods fail to capture the full process of metastases and only capture seeding in the distant location. Champions Oncology utilizes its innovative Champions Tumorgraft™ platform where primary human tumors are implanted into immunocompromised mice in a manner that preserves the biological properties of the original human tumor. As part of its extensive characterization, Champions has recently observed an increasing number of Champions Tumorgraft™ models demonstrating spontaneous metastatic lesions following subcutaneous (s.c.) implantation. The tumor types demonstrating spontaneous metastasis include breast, melanoma, colorectal, esophageal adenocarcinoma, and head and neck squamous cell carcinoma. Two Champions Tumorgraft models highlighted in this report are CTG-0033, a breast cancer model, and CTG-0213, a melanoma model. These Champions Tumorgraft models demonstrate frequent metastases to the liver and spleen following s.c. implantation. For model CTG-0033, metastases were seen in greater than 75% of the animals following implantation. The metastatic behavior of this Tumorgraft model also parallels the clinical disease progression. For instance, CTG-0033 was derived from a breast cancer patient who, following the development of the Tumorgraft model, developed extensive metastases. Given that treatment failures clinically are often due to recurrence of the tumor at metastatic locations, there is significant need for in vivo models that replicate the spontaneous metastatic process. Overall, numerous Champions Tumorgraft models implanted s.c. exhibit spontaneous metastatic behavior and are therefore ideal models for oncology drug development focused on inhibition of metastases.

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 B18.
Abstract B19: Innovative tools to evaluate genetic targets and the efficacy of novel cancer therapeutics.
Authors: Kissel Holger , Xu Yan , Tugusheva Marina , Seibler Jost , Jonkers Jos , Grass David , Buiakova Olesia
Published: June 2012

More predictive small animal models for compound and genetic target assessment are needed to improve development of more efficacious drugs. For assessment of novel cancer therapeutics we have developed an in vivo and ex vivo bioluminescent imaging platform to evaluate compound efficacy. In these mouse models orthotopic tumor grafts are being used that are more relevant with respect to host-tumor interactions, display metastatic potential and allow the evaluation of responses to novel therapeutics. These models closely mimic the progression of human disease and allow quantitative analysis and high throughput in vivo assessment of potential anti-tumor activity.

In addition we will present an oncology platform using mouse models for breast cancer. The Brca1/p53 breast cancer model resembles hormone receptor- and ERBB2-negative (“triple-negative”) mammary carcinomas and shows responses to therapies similar to humans, including the emergence of drug resistance. We will present an orthotopic allograft system using primary tumors from Brca1/p53 deficient mice to allow the generation of cohorts developing breast cancer. These grafted mice can readily be used for testing of novel therapeutics in a tumor model resembling human disease.

Finally, we will present a transgenic RNAi system that can be used for studying the loss-of-function of target genes. We will present how this system can be used to develop novel disease models and how potentially this model can be combined with disease models to study the genetic loss of a drug target in an established disease state.

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 B19.
Abstract B204: Engineered cysteine antibodies: Improved antibody-drug conjugate vehicles.
Authors: Sussman Django , Torrey Lindsay , Westendorf Lori , Zhang Xinqun , Okeley Nicole M. , Alley Stephen C. , Lyon Robert , Meyer David , Miyamoto Jamie B. , Benjamin Dennis R.
Published: June 2012

The use of monoclonal antibodies for the delivery of anticancer drugs to tumor cells is an emerging therapeutic modality and has been the subject of a great deal of investigation. In this study we have engineered antibody variants with an additional cysteine residue in the each heavy chain to provide a route towards homogenous two drugs per antibody loading while interfering with Fc gamma receptor binding. We have characterized the relationship between the site of drug conjugation and a number of key parameters including relative protein expression, conjugatability, drug-linker stability, effects on biophysical properties of the resulting antibody-drug conjugate (ADC), and in vitro cytotoxicity. We demonstrate that the site of conjugation affects many of these parameters and that Engineered Cysteine (EC) antibodies can be considered a viable next generation ADC approach.

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 B204.
Abstract B24: Detection of O6- and N7-methylguanine adducts by LC/MS in brain tumor tissues obtained from patients treated with temozolomide.
Authors: Sadr Emad Seyed , Catana Dragosh , Tessier Alain , Sadr Mohamad Seyed , Alshami Jad , Sabau Carmen , Del Maestro Rolando
Published: June 2012

The current standard of care for glioblastoma includes surgery, radiotherapy and chemotherapeutic agents such as temozolomide (TMZ), a DNA methylating compound. The cytotoxic effects of TMZ have been linked to guanine methylation at the N7 and O6 positions. These adducts are not currently used as markers of TMZ efficacy.

Using liquid chromatography/mass spectrometry (LC/MS), we have established a sensitive analytical assay to directly detect both N7- and O6-methylguanine adducts from DNA following TMZ treatment. A limit of detection below 1 fmol was observed for O6-methylguanine, while N7-methylguanine was observed below 5 fmol. O6- and N7-methylguanine were successfully detected by LC/MS in tumour and normal brain tissue samples from patients treated with a neoadjuvant TMZ regimen for 14 days (75 mg/m2). Variations in levels of both methylated guanines were detected between patients as well as within different locations of the same tumour sample. This technique provides a direct detection of the damage inflicted by TMZ. This could potentially indicate the efficacy of the drug, allowing for prompt analysis and response. It also holds potential for determining efficacy of treatment dose, schedule and possible concomitant drugs.

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 B24.
Abstract B38: Troglitazone enhances breast cancer cell 18F-FDG uptake and intracelluar lactic acid accumulation through PPAR-r independent activation of the MAPK pathway.
Authors: Lee Su Jin , Paik Jin-Young , Cung Quach , Jung Kyung-Ho , Lee Kyung-Han
Published: June 2012

Purpose: There is growing interest in the anti-tumor effects of thiazolidinediones including troglitazone (TGZ). In this study, we assessed how TGZ acts on cancer cell glucose uptake, and further investigated its mechanism and relation to cancer cell survival.

Methods: T47D human breast cancer cells were treated with TGZ and measured for trypan blue and MTT assay-based cell viability, FDG uptake, intra- and extracellular lactic acid levels, and superoxide production. Involvement of signaling pathways for FDG uptake was investigated with specific kinase inhibitors and Western blots.

Results: TGZ caused dose-dependent suppression of T47D cell survival, and glucose deprivation substantially enhanced the killing effect from 15.6% to 84.2% of cells. However, in contrast to energy restriction mimetic agents that reduced FDG uptake, TGZ stimulated a prompt increase of FDG uptake that reached 245.0% of controls by 10 μM at 1 h. This response was poorly replicated by rosiglitazone and was unaffected by GW9662, indicating a PPAR-independent mechanism of action. TGZ rapidly stimulated mitogen-activated protein kinase (MAPK) activity, and inhibition of this pathway with PD98059, as well as inhibition of epidermal growth factor receptor (EGFR) activity with BIBX1382, completely abrogated the ability of TGZ to enhance FDG uptake. The increase in glucose uptake was accompanied by elevated lactic acid accumulation in the cells but not culture media. This indicates that TGZ stimulates glycolytic activity but suppresses lactic acid extrusion, which may contribute to its anti-tumor effects.

Conclusion: TGZ-induced suppression of T47D cell survival is potentiated by restricted glucose availability, but is uniquely accompanied by enhanced FDG uptake that occurs via PPAR-independent MAPK activation. This is associated with an increase in glycolytic metabolism along with suppression of lactic acid extrusion, which may play a role in the anti-tumor effect of TGZ.

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 B38.
Abstract B4: An important regulatory role of HDM2 in tumor angiogenesis pathway.
Authors: Muthumani Praneetha , Rathinavelu Appu
Published: June 2012

HDM2 is a master regulator and plays an important role in Tumor angiogenesis. To confirm this hypothesis, we used wild type LNCaP and HDM2 transfected LNCaP-MST prostate cancer cells for our study. In the HDM2 transfected cells we observed 96% higher HDM2 protein expression compared to LNCaP cells. In general, HDM2 over expression has been reported to be a potential cause for p53 degradation in many cancer cells. To confirm this negative correlation, p53 level was observed in HDM2 transfected cells. Compared to the wild type cells, only 10% of the p53 level was found in the HDM2 transfected LNCaP-MST cells. This confirms our speculation that, HDM2 mediated degradation of p53 may occur in LNCaP-MST cells. Following HDM2 transfection, the VEGF level was also increased by 180% in LNCaP-MST cells compared to LNCaP cells. Since, previous studies have indicated that HIF-1α has a major role in inducing VEGF transcription, we determined the level of HIF-1α in both cells. In LNCaP-MST cells, nearly 90% higher HIF-1α protein level was observed, this might be due to the inhibition of both prolyl hydroxylase and factor inhibiting HIF (FIH) activity by HDM2, which are essential to hydroxylate HIF-1α in critical position. Once, hydroxylated, HIF-1α can no longer bind to p300 and induce VEGF transcription. In addition, an increase in the activated form of STAT3 (p-STAT3) causing elevated VEGF transcription has been previously reported in many cancer cells. Accordingly, the p-STAT3 protein expressions observed in HDM2 transfected LNCaP-MST cells were 15 folds higher compared to the non-transfected wild type LNCaP cells. A negative regulatory role of p53 in controlling the levels of active STAT3 has also been previously reported in prostate cancer cell lines. Hence, it is suggested that HDM2 might be inducing the expression of active STAT3 by degrading p53 protein in LNCaP-MST cells. Overall, our results demonstrate that HDM2 has an important role in regulating the VEGF transcription via modulating HIF-1α and STAT3 protein expressions.

We thank the Royal Dames of Fort Lauderdale, Inc. for their support.

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 B4.
Abstract B43: Effects of anticancer drugs on cancer cells under hypoxic conditions.
Authors: Laitinen Sara , Fryknas Marten , Larsson Rolf , Gullbo Joachim
Published: June 2012

Introduction. Environment inside even a small tumor is characterized by total or partial oxygen deprivation, hypoxia. It has been shown that radiotherapy and some traditional chemotherapies are often less effective in hypoxia, and therefore it is important to investigate how different drugs act in different microenvironments. In this study we perform a screening of the effects of 15 clinically used chemotherapeutic drugs on five different cell lines in conditions of normoxia, hypoxia and anoxia.

Material and method. A panel of 15 commercially available drugs: 5-fluorouracil, acriflavine, cisplatin, digitoxin, digoxin, docetaxel, doxorubicin, etoposide, irinotecan, melphalan, mitomycin c, rapamycin, sorafenib, thalidomide and tirapazamine, was tested on the cancer cell lines A2780 (ovarian), ACHN (renal), MCF-7 (breast), H69 (SCLC) and U-937 (lymphoma). Parallel aliquots of the cells were grown at different oxygen pressures and after 72 hours of drug exposure fluorometric microculture cytotoxicity assay was performed.

Result and discussion. As shown in table 1 sorafenib, irinotecan and docetaxel were in general more effective in an oxygenated environment, while cisplatin, mitomycin c and tirapazamine were more effective in a low oxygen environment. Surprisingly, hypoxia in H69, MCF-7 and U-937 cells mostly rendered higher drug sensitivity. In contrast ACHN appeared more sensitive to hypoxia, giving slower proliferating cells, and consequently, was more resistant to most drugs in hypoxia.

Conclusion. A panel of standard cytotoxic agents was tested against five different human cancer cell lines cultivated at normoxic, hypoxic and anoxic conditions. Results show that impaired chemosensitivity is not universal, in contrast different cell lines behave different and some drugs appear even less effective in normoxia.

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 B43.
Abstract B46: Effective therapeutic response of MDA-MB-231 cell line to rapamycin.
Authors: Ferreira Livia C. , Lopes Juliana R. , Jardim Bruna V. , Leonel Camila , Gelaleti Gabriela B. , Caldas Heloisa C. , Abbud Mario F. , Zuccari Debora A.P.C.
Published: June 2012

The assessment of alternative therapeutics agents can develop more effective treatments in breast cancer, resulting in molecular-targeted drugs, developed from the knowledge of molecules involved in specific pathways that provide growth and progression of cancer. A large number of studies have suggested that immunosuppressive agents can act as powerful anti-cancer drugs. Rapamycin, a potent immunosupressor used routinely in transplant patients, also has antiproliferative, antifungal and antimicrobial activity. Recent studies show that rapamycin can alter the function of blood vessels by promoting thrombosis in tumor vessels and thus prevents the formation of tumor vasculature. In addition, experiments have focused on the antiangiogenic effects, antiproliferative and antimetastatic target protein inhibitors of rapamycin (mTOR), affecting the expression of genes involved in metabolism and protein synthesis. Thus, believing in the inhibitory effect of rapamycin in tumor progression in diferent tumor types, this study evaluated its antitumor activity in mammary tumoral cell line. Samples of breast cancer cell line, MDA-MB-231 (estrogen receptor negative) were cultured in medium DMEM with high glucose concentration (Cultilab), and incubated at 37° C in 5% CO2. All culture medium used was enriched with 20% BSA, 1% penicillin/streptomycin and 1% L-glutamine. It was established five groups, four of them received different concentrations of rapamycin (group I - 1nM, group II - 10nM, group III - 50nM and group IV - 100nM) and one group was classified as control group (control - group V). After the interval of 72 hours of application of rapamycin, cells were stained with Trypan Blue (cell vitality). The growth curve was performed by counting cells in a Neubauer chamber, in order to evaluate the effects of drug. After 72 hours, the group V contained 200 cells. In the treated groups I and II, there was a small decrease in cell number, reaching 180 and 150 cells, respectively. In group III, there was a reduction in cell number reached 118 cells and in group IV was observed 50% reduction in the number of cells compared to group V. These results prove that rapamycin is effective in controlling cell proliferation and causes a decrease in the number of cells. In addition, the action of rapamycin may be dose dependent, as increasing the dose applied in the same cell concentration there was a decrease in the amount of cells. This fact suggests that rapamycin can be a possible alternative to the establishment of therapeutic strategies for 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 B46.
Abstract B52: A phase I-IIA, dose-escalating study of intravenous melphalan-flufenamide (J1) in adult patients with advanced solid tumors (I), advanced ovarian cancer, or non-small cell lung cancer (IIA).
Authors: Gullbo Joachim , Berglund Ake , Ullen Anders , Larsson Rolf , Lewensohn Rolf , Nygren Peter , Spira Jack
Published: June 2012

Introduction: Melphalan-flufenamide (previously designated J1) is an enzyme-activated (aminopeptidase N, APN) prodrug of melphalan. The mechanism of enzyme activation results in the selective intracellular trapping of melphalan in tumor cells. Treatment with melphalan-flufenamide results in a 10–20 fold higher intracellular concentration of melphalan in tumor cells than treatment with equal doses of melphalan, and has demonstrated enhanced cytotoxic activity in numerous in-vitro and in-vivo assays. Consistent with these observations, exposure to melphalan-flufenamide results in greater reductions in the rate of DNA synthesis and greater pro-apoptotic effects than direct treatment with the same doses of melphalan.

Experimental: In the dose-escalating phase I part of this study patients with end-stage solid tumor malignancies were admitted. After definition of Recommended Phase Two Dose (RPTD) the trial shifted to a phase IIA trial and only patients with selected diagnoses could be included.

Results: The dose limiting toxicity was bone marrow suppression, mainly reversible thrombocytopenia. This was particularly evident in heavily pretreated patients, and RPTD was set to an intravenous infusion of 50 mg (fixed dose) every third week. No cumulative toxicity was observed. In the phase IIA part of the study forty patients were included, twenty of which had ovarian cancer, and thirteen NSCLC. The ovarian cancer patients had received 3–8 previous lines of chemotherapy (mean 3.9, and 90 % had received both taxane and platinum drugs), the NSCLC patients 2–4 lines (mean 2.5, 100 % had received platinum drugs). Twenty-four patients could be radiologically evaluated after 3 cycles of melphalan-flufenamide. Out of twelve evaluable ovarian carcinoma patients two had PD, nine had SD and one had PR according to RECIST criteria. Two patients with SD had a CA125 response of −50 and −70 % respectively. Two patients with SD had clinical progression (ascites effusion) shortly after first evaluation. Eleven patients with NSCLC were evaluated; three had PD and eight SD, according to RECIST. Thus, in NSCLC disease stabilization was best response, one patient received nine cycles of melphalan-flufenamide, and progressed after seven months of therapy.

Summary: The APN-activated prodrug melphalan-flufenamide can safely be given to cancer patients. Dose is limited by hematological toxicity. The study suggests clinical activity (biochemical and radiological) in ovarian cancer, even after failure to several lines of chemotherapy.

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 B52.
Abstract B60: Phenothiazines inhibits repair of chemotherapy-induced DNA double-strand break in tumor but not in normal fibroblasts by modulating chromatin configuration.
Authors: Zong Dali , Haag Petra , Yakymovych Ihor , Lundholm Lovisa , Lewensohn Rolf , Viktorsson Kristina
Published: June 2012

Acquisition of drug resistance mechanisms by tumor cells poses severe limitations on the efficacy of conventional chemotherapy. Since most clinically useful chemotherapeutic agents cause DNA damage, suppression of tumor DNA repair capacity is expected to enhance tumor eradication. Based on earlier observations that phenothiazine compounds confer chemosensitization in lung cancer cells, we investigated whether these compounds could modulate DNA repair and the molecular details of their mechanisms of action. Colony formation and MTT assays were used to demonstrate phenothiazine-mediated chemosensitization. Immunoblotting, immunofluorescence and FACS studies were used to probe the effects of phenothiazines on DNA repair. Modulation of chromatin structure was achieved by increasing or decreasing the salt content in the culture media. In silico predictions of drug action based on gene signatures was performed by Connectivity Mapping. Our data revealed that phenothiazine co-treatment along with DNA damaging agents (e.g., bleomycin, cisplatin) resulted in sustained activation of, DNA-PK and FancD2, both of which are involved in DSB repair, even many hours after the removal of the DNA damaging agent. This effect was observed in a variety of human tumor cell lines, including those derived from lung-, breast- and ovarian cancer. Notably, repair of DNA damage by non-transformed fibroblasts and epithelial cells was not antagonized by phenothiazines, revealing a potential selectivity for tumor cells. Modulation of DSB repair by phenothiazines was sensitive to osmolality of the culture media. In addition, gene signature induced by phenothiazine treatment showed similarities to gene signatures induced by HDAC inhibitors. Taken together, phenothiazines may represent a novel of class of chemosensitizers which disrupt DSB repair by altering chromatin configuration.

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 B60.
Abstract B63: Targeting cancer cells with a glucose-conjugated DNA repair inhibitor.
Authors: Tomaszowski Karl-Heinz , Schirrmacher Ralf , Schirrmacher Esther , Kaina Bernd
Published: June 2012

Alkylating agents are important chemotherapeutic drugs used for the treatment of several types of cancers, including brain tumors, melanoma and lymphoma. These chemotherapeutic agents have a strong affinity towards oxygen atoms in DNA giving rise to the important genotoxic DNA lesions O6-methylguanine and O6-chloroethylguanine, which are responsible for the cytotoxic effects of several alkylating anticancer drugs (e.g. temozolomide and lomustine). The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) is considered as an important player of drug resistance because it removes these DNA adducts from the DNA. The MGMT protein restores guanine in the DNA by a suicide repair reaction leading to irreversible inactivation and degradation of the protein. Therefore depletion of MGMT renders cells more susceptible to treatment with alkylating anticancer drugs. There has been numerous attempts to inactivate MGMT with different inhibitors like O6-benzylguanine (O6-BG) or O6-(4-bromothenyl) guanine (O6-BTG, lomeguatrib) in glioblastoma and malignant melanoma cells. These strategies however have failed thus far, mainly due to the severe side effects associated with the systemic sensitization of the patients to chemotherapeutic agents. The application of targeting strategies for MGMT inhibitors therefore should improve chemotherapy by selective inhibition of MGMT in the tumor. In our previous work we have shown that O6-BG and O6-BTG bound to glucose is efficient in inhibiting MGMT on enzyme level and in the cell, causing sensitization to DNA alkylating N-nitrosoureas (Kaina et. al., 2004; 2010). Here we show, using a quantitative MGMT assay, that intracellular uptake of O6-benzylguanine-C8-glucose (O6-BG-Glu) occurs by a transporter-dependent mechanism and not through passive diffusion. We observed differences in the transport kinetics between several cell lines. Most cancer cell lines are able to take up the inhibitor, whereas normal cells only show marginal uptake of the glucose-conjugated inhibitor. The uptake is probably not depended on the glucose transporter GLUT since blocking of GLUT does not abolishes MGMT inhibition. Uptake of the glucose conjugated inhibitors in cancer cells leads to an increased DNA damage response, induction of apoptosis and significant decrease in surviving fraction after treatment with alkylating anticancer drugs, pointing to the usefulness of the glucose-mediated MGMT inhibitor targeting strategy. References: Kaina et al., J. Pharmacol. Expt. Therap., 311, 585–593 (2004); Kaina et al., Cell. Mol. Life Sci., 67, 3663–3681 (2010)

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 B63.
Abstract B64: Structure and preclinical characterization of BMN 673, a potent and orally active PARP inhibitor as an anticancer agent.
Authors: Shen Yuqiao , Feng Ying , Wang Bing , Myers Peter , Chu Daniel , Post Leonard E.
Published: June 2012

In this presentation we will present the chemical structure, biological activity and pharmacokinetic (PK) properties of BMN 673, a potent inhibitor of poly (ADP-ribose) polymerases (PARP)-1 and -2. PARP-1 and -2 are key nuclear enzymes that are activated by DNA damage and play a critical role in the base excision DNA repair (BER) pathway. Inhibitors of PARP-1 and -2 could enhance the cytotoxicity of DNA damaging agents by preventing cancer cells from repairing DNA damage. In addition, PARP inhibitors have been shown to selectively kill cancer cells that are deficient in BRCA-1 or BRCA-2 function. A previously unexplored chemical scaffold was discovered with good PARP inhibitory activity. Optimization of this scaffold produced BMN 673, the most potent PARP inhibitor reported to date. BMN 673 selectively kills cancer cells with BRCA-1 or BRCA-2 mutations. In xenograft tumor model studies, oral dosing of BMN 673 results in complete regression of the BRCA-deficient tumors. In addition to BRCA-1/2 mutations, we examined the correlation of other DNA repair defects with the tumor cells' sensitivity to BMN 673 treatment. We show that tumor cells with PTEN mutation are highly sensitive to BMN 673 treatment in vitro. Xenograft tumor models that harbor PTEN deficiency responded to oral BMN 673 treatment with significant tumor growth delay. Deficiencies in ATM and other homologous recombination (HR) DNA repair genes, as well as unidentified genetic deficiencies, result in sensitivity to cell killing by BMN 673 in head-and-neck cancer, myeloma, and mantle cell lymphoma. These results suggest that BMN 673 may be a valid treatment option for cancers with these genetic defects. In animal PK/PD studies, BMN 673 displays good oral bioavailability and PK properties, and demonstrates significant in vivo PARP inhibition in xenograft tumors and other tissues. BMN 673 is currently in phase 1 clinical trials in patients with solid tumors or hematological malignancies.

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 B64.
Abstract B78: A novel EWS/Fli1 target gene, Eya3, is upregulated in Ewing's sarcoma to mediate chemoresistance.
Authors: Robin Tyler P. , Kreuger Aaron , McKinsey Erin , Reaves Lisa , Jedlicka Paul , Zhao Rui , Ford Heide L.
Published: June 2012

Ewing's sarcoma is an aggressive pediatric cancer of the bone and soft tissue, in which patients' whose tumors have a poor histological response to initial chemotherapy have a poor overall prognosis. Importantly, childhood cancer survivors are faced with long-term chemotherapy-associated toxicities many years after they have been cured of their primary disease. Therefore, targeting molecules involved in resistance to chemotherapy should benefit patients with resistant disease and allow lower doses of toxic chemotherapies to be used in treatment regimens, thus improving outcomes for children suffering from Ewing's sarcoma on multiple fronts. The vast majority of Ewing's sarcomas harbor a characteristic translocation, t(11;22), encoding the EWS/Fli1 fusion protein. We have identified the DNA-repair protein and transcriptional cofactor, Eya3, as a downstream target of EWS/Fli1. Eya3 is highly expressed in Ewing's sarcoma tumor samples and cell lines compared with mesenchymal stem cells, the presumed cell of origin of Ewing's sarcoma. We demonstrate that EWS/Fli1 mediates upregulation of Eya3 via repression of miR-145 and miR-708, microRNAs that target the Eya3 3'UTR. Furthermore, replacement of miR-145 and miR-708 in a Ewing's sarcoma cell line decreases Eya3 levels. It was recently shown that Eya3 promotes DNA repair by dephosphorylating a critical tyrosine residue on H2AX in response to DNA damage, resulting in the recruitment of DNA repair factors to the sites of DNA damage. Thus we tested whether knockdown of Eya3 in Ewing's sarcoma cells would decrease cell survival and sensitize cells to DNA-damaging chemotherapeutics used in the treatment of Ewing's sarcoma: etoposide and doxorubicin. Indeed, Eya3 knockdown led to increased cell death and sensitization to chemotherapy, and, as expected, Eya3 knockdown cells contained more DNA damage following treatment with etoposide than their control counterparts. These data strongly suggest that Eya3 mediates chemoresistance in Ewing's sarcoma through its ability to enhance DNA repair. Because Eya3 mediates DNA repair and survival via its intrinsic phosphatase activity, and because the phosphatase activity of Eya is also known to play a role in metastasis of other cancers, we have begun to develop inhibitors targeting the Eya phosphatase activity and to demonstrate their efficacy both in vitro and in cell culture. In closing, Eya phosphatase inhibitors or synthetic mimics of the microRNAs targeting Eya3 have the potential to improve outcomes for Ewing's sarcoma patients by improving therapeutic efficacy and decreasing associated toxicities of conventional chemotherapeutics.

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 B78.