bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2505: Neurotensin receptor antagonist, SR48692, sensitizes prostate cancer cells to radiation in vitro and in vivo
Authors: Casarez Eli V. , DaSilva John O. , Valerie Nicholas C.K. , Anaganti Suresh , Dunlap-Brown Marya E. , Amorino George P. , Larner James M. , Parsons Sarah J. , Dziegielewski Jaroslaw
Published: June 2012

Prostate cancer (PCa) is one of the major causes of cancer-related deaths in men. Androgen receptor (AR) and androgen sensitivity play a crucial role in the development of the disease. Thus, androgen depletion therapy has become a cornerstone of advanced PCa treatment, with or without radiotherapy. Multiple mechanisms have been proposed for the development of hormone-refractory disease, including an increase in neuroendocrine-like (NE-like) cells, which secrete survival and growth factors for surrounding tumor cells (Deeble et al., Cancer Res 2007). Neurotensin (NT) is secreted by both NE-like and cancer cells, and stimulate proliferation of PCa cells through its interaction with neurotensin receptor 1 (NTR1) (Amorino et al., Oncogene, 2007). In this report we investigate the efficacy of a NTR1 antagonist, SR48692, as a radiosensitizer in an orthotopic PC-3M xenograft model. The role of AR/sensitivity to androgen in response to SR48692 was also investigated using LNCaP and C4-2 cell lines. The latter studies were done to test the hypothesis that AR positive cells may be refractory to the raditherapy, because we had previously shown that neuropeptides from NE-like cells resulted in Src-mediated phosphorylation of AR (DaSilva et al., Cancer Res 2009). The results of the xenograft studies indicate that mice bearing PC-3M tumors and receiving the combination treatment (drug+radiation) showed a statistically significant decrease in tumor growth over radiation or SR48962 treatments alone. SR48692 was also found to radiosensitize PCa cells in vitro, independently of their androgen receptor/androgen sensitivity status. We further demonstrate that NT stimulates accumulation of AR under conditions of reduced androgen and that this activity is blocked by SR48692/radiation co-treatment. These findings suggest that in cells expressing the AR, NT reduces the efficacy of radiation by elevating AR levels and its ensuing pro-growth and -survival signals. Blocking the actions of NT by SR48692 reduces the levels of AR protein and as a result increases cellular sensitivity to radiation. However, in cells lacking the AR, another mechanism(s) of drug action must be operative. Together, our studies suggest that in AR positive or negative PCa cells, NTR1 signaling pathway(s) are novel targets for combined SR48962/radiotherapy of PCa.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2505. doi:10.1158/1538-7445.AM2011-2505
Abstract 2520: Ku-dependent non-homologous end-joining interferes the efficiency of Mre11 binding to replication related DNA double strand breaks
Authors: Wang Hongyan , Zhang Xiangming , Wang Ya
Published: June 2012

Background: Camptothecin (CPT), an inhibitor of DNA topoisomerase I, induces replication related DNA double strand breaks (DSBs). Previously, it was reported that Ku-dependent non-homologous end-joining (NHEJ) deficient DT40 cells were more resistant to CPT-induced killing than wild type cells (JBC, 279:37343, 2004), however, the mechanism remains unclear. We were interested in testing the hypothesis that Mre11 binding to DNA double strand break (DSB) (the first step for initiating homologous recombination repair (HRR)) is interfered by the Ku-dependent NHEJ and the interference was much stronger in S phase.

Methods: Different fork-related DNA structures were designed for testing the efficiency of purified Mre11 protein (kindly provided by Dr. Tainer) in vitro. DT40 cell lines: wild type, Ku70-/, DNA-PKcs-/-, Rad54-/- and Rad51 conditional knock out cells were used in this study. The efficiency Mre11 binding to chromatin DNA in CPT treated the cell lines were detected. The cell cycle distribution was measured by a flow cytometer. The sensitivity of these cell lines to CPT were measured by a clonogenic assay.

Results: Compared with their wild-type counterparts, Rad54−/− and Rad51 conditional knock out cells (essential factors for (HRR)) were much more sensitive to CPT-induced killing but Ku70−/− and DNA-PKcs cells (essential factors for non-homologous end joining (NHEJ)) were much more resistant to CPT-treated killing, which was accompanied by a huge S-phase block in these resistant cells. Mre11 bound to DNA substrates especially to the mimic DNA replication fork substrates. Mre11 bound to chromatin DNA in Ku70-/- and DNA-PKcs-/- cells stronger than that in wild type cells following CPT treatment.

Conclusion: CPT-induced S checkpoint facilitates Mre11 binding and promotes HRR, which protects cells from CPT-induced killing. The Ku-dependent NHEJ block efficiency of Mre11 binding to DNA substrates especially DNA replication related structure, which inhibits HRR and renders sensitivity of the cells to CPT treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2520. doi:10.1158/1538-7445.AM2011-2520
Abstract 2527: Amonafide and its metabolite N-acetyl amonafide are Top2 poisons with differing biochemical properties
Authors: Soans Eroica , Shanmuganatham Karthik , Rogojina Anna , Nitiss John L.
Published: June 2012

Naphthalimides derivatives have been extensively studied as anti-cancer agents. Amonafide (5-amino-2-[2-(dimethylamino)ethyl]-1H-benzo[de]isoquinoline-1,3(2H)-dione) showed clinical activity especially in some groups of AML patients. Amonafide has been shown to target topoisomerase II (Top2), and to stabilize Top2 covalent complexes. Therefore, the agent is a Top2 poison, however, the compound shows some unusual properties. Unlike most Top2 poisons, the action of amonafide against Top2 is largely ATP independent; In addition, amonafide leads to cleavage of DNA at a very restricted set of sites compared to other Top2 poisons such as mitoxantrone or etoposide. These findings have led to suggestions that amonafide may target Top2 in an unconventional way. Another obstacle to the clinical use of amonafide is variable drug metabolism. Felder and colleagues showed that amonafide is metabolized by N-acetyl transferase 2 (NAT2) to form N-acetyl amonafide (NAA). Toxicity of amonafide regimens is associated with higher levels of NAT2 activity 2. The mechanism of NAA toxicity has not been reported. We have used the ICE assay developed by Muller and colleagues to assess Top2 covalent complex levels in cells treated with either amonafide or NAA. We found that amonafide induces Top2 mediated DNA cleavage, and that covalent complexes formed by both Top2 alpha and Top2 beta were seen. Interestingly, NAA induced higher levels of Top2 covalent complexes than the parent compound. In addition, the level of Top2 covalent complexes increased with increasing NAA dose, whereas a plateau in the level of Top2 covalent complexes was seen with amonafide at relatively low doses. We are currently comparing the action of amonafide and NAA against purified human topoisomerases. We suggest that NAA is a Top2 poison, and a plausible hypothesis is that NAA may act more like a conventional Top2 poison, while amonafide may show a better therapeutic index because it has more limited potential for forming Top2 covalent complexes. These results may be useful in the further development of amonafide derivatives with a favorable therapeutic profile.

(1) Felder, T. B.; McLean, M. A.; Vestal, M. L.; Lu, K.; Farquhar, D.; Legha, S. S.; Shah, R.; Newman, R. A. Drug Metab Dispos 1987, 15, 773.

(2) Ratain, M. J.; Rosner, G.; Allen, S. L.; Costanza, M.; Van Echo, D. A.; Henderson, I. C.; Schilsky, R. L. J Clin Oncol 1995, 13, 741.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2527. doi:10.1158/1538-7445.AM2011-2527
Abstract 2540: Evaluation of novel bis-amidine osmium complex as anti-proliferative agents
Authors: Ajay Matta , DeSouza Leroi V. , Lau T. C. , Siu K.W. Michael
Published: June 2012

Introduction. Despite improvement in current treatment strategies, including surgery, chemotherapy (CT) and radiotherapy (RT), survival of cancer patients in advanced stages has not improved significantly over the last decade. Organometallic complexes of platinum (cisplatin, carboplatin and oxaliplatin) are in use as chemotherapeutic agents worldwide. However, acquired drug resistance to these platinum complexes has necessitated the search for novel strategies to overcome this limitation, which includes combination therapies and the development of novel platinum or non-platinum complexes as drugs.

Methods. Anti-proliferative effects of a bis-amidine complex (Os-Sh1) was determined by measuring the inhibition of cell proliferation using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry-based cell-cycle analysis, annexin V dye binding assay and TUNEL assay in endometrial cancer (Hec1A and KLE) and cervical cancer (HeLa) cells.

Results: Cell viability (MTT) assays revealed inhibition of cell proliferation on treatment with the bis-amidine osmium complex (Os-Sh1) in HEC1A, KLE and HeLa cell lines in a dose- (1μM – 50μM) and time-dependent manner (24h – 96h). Cell-cycle analysis showed increased cell death, i.e. the sub-G0 fraction, with G0/G1-arrest and reduction in the G2/M phase of cell cycle on treatment with the Os-Sh1 in these cell lines. Results of annexin V assay suggested apoptosis as the mechanisms of Os-complex induced cell death. Apoptosis was further confirmed by TUNEL assay using flow cytometry analysis. Western blot analysis showed cleavage of caspase 9, caspase 3 and poly-ADP ribose polymerase (PARP), suggesting activation of the intrinsic mitochondrial pathway of apoptosis. Interestingly, Os-Sh1 was more effective in inhibiting cell proliferation at a lower dose and shorter period of time (LD50=20 μM, 48h) in comparison to cisplatin, carboplatin and oxaliplatin in HEC1A, KLE and HeLa cell lines.

Conclusions: Our in vitro data clearly demonstrated anti-proliferative effects of a novel bis-amidine osmium complex in endometrial and cervical cancer cells at a lower dose and in shorter period of time in comparison to platinum drugs. Based on these results, we hypothesize that such osmium complex has the potential as effective cytotoxic agents wherein cancer cells acquire resistance to commonly used platinum drugs.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2540. doi:10.1158/1538-7445.AM2011-2540
Abstract 2541: Inhibition of DNA repair by trifluoperazine sensitizes human lung cancer cells to apoptosis associated with lysosomal dysfunction following prolonged G2-M checkpoint arrest
Authors: Zong Dali , Hååg Petra , Lewensohn Rolf , Viktorsson Kristina
Published: June 2012

Clinical therapy resistance severely limits the efficacy of DNA damaging chemotherapy in human lung non-small cell lung carcinoma (NSCLC). Here we show that chemosensitization can be achieved in NSCLC by combining clinically-relevant DNA damaging agents with trifluoperazine (TFP). Colony formation assays demonstrated that TFP significantly potentiated the cytotoxicity of bleomycin and cisplatin in NSCLC cell lines. TFP impaired the repair of bleomycin- and cisplatin-induced DNA double strand breaks (DSBs), and consequently delayed the recovery from DNA damage-induced G2-M checkpoint (12 h vs at least 24 h). At later time points (> 24 h), NSCLC cells co-treated with TFP and bleomycin or cisplatin were able to overcome the initial G2-M checkpoint arrest, as evidenced by the reappearance of the mitosis markers and reduction in CFSE fluorescence. However, these cells showed increased micronucleation, apoptosis and gradual loss of proliferative capacity due to secondary G2-M arrest. Notably, TFP co-treated NSCLC cells underwent limited lysosomal membrane permeabilization (LMP) prior to Bak/Bax activation and mitochondrial depolarization. In turn this led to robust activation of caspase-3 preferentially in cells residing in the G2-M phase. In conclusion, our data supports the notion that by antagonizing DSB repair, TFP forces NSCLC cells into prolonged checkpoint arrest (whether initial or secondary) which sensitizes them to apoptosis associated with lysosomal dysfunction.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2541. doi:10.1158/1538-7445.AM2011-2541
Abstract 2546: AXL targeted therapy blocks tumor progression and prevents tumor metastasis in pancreatic cancer
Authors: Rajeshkumar N.V. , Karikari Collins , DeOliveira Elizabeth , de Wilde Roeland F. , Holland Sacha J. , Payan Donald G. , Maitra Anirban
Published: June 2012

Background: Metastasis and drug resistance are the major causes of mortality in patients with pancreatic ductal adenocarcinoma (PDA). Once developed, the progression of PDA metastasis is virtually unstoppable with current therapies. Accumulating evidence suggests important roles for the receptor tyrosine kinase AXL in cancer progression, invasion, metastasis, drug resistance, and patient mortality. Given the critical influence of metastasis on the clinical history of PDA, we hypothesize that pharmacological inhibition of AXL might inhibit tumor growth and prevent PDA metastasis.

Methods: We investigated the AXL expression in a panel of human pancreatic cancer xenografts using Affymetrix gene array as well as qRT-PCR. We conducted a comprehensive preclinical trial to determine whether AXL targeted monotherapy, and in combination with gemcitabine, was effective in blocking PDA tumor progression and metastasis using subcutaneous as well as orthotopic pancreatic cancer models.

Results: R428, a potent selective small molecule inhibitor of AXL, inhibited proliferation of pancreatic cancer cell lines in a concentration-dependent manner. A combination of R428 with gemcitabine could significantly inhibit primary tumor growth compared to gemcitabine treated mice. Notably, R428 alone and in combination with gemcitabine was remarkably effective in preventing the development of metastasis to organs and lymph nodes as compared to gemcitabine treatment in a highly aggressive orthotopic model.

Conclusions: The data presented here provide strong evidence for the therapeutic development of AXL inhibitors as anti-metastatic agents in pancreatic cancer. A combination treatment of R428 and gemcitabine was highly effective in controlling the primary tumor growth and preventing metastatic spread. The novel therapeutic approach tested here has potential therapeutic implications for improving the current standard of care for PDA patients and to contribute towards making PDA a more manageable disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2546. doi:10.1158/1538-7445.AM2011-2546
Abstract 2553: Inhibition of γ-secretase in combination with Lapatinib induces tumor regression in vivo
Authors: Pandya Kinnari , Meeke Kathleen , Rogowski Allison , Clementz Anthony , Osipo Clodia
Published: June 2012

Amplification, over-expression, and/or hyperactivity of ErbB-2 occur in 15-30% of breast tumors which include both luminal B and the HER2+ subtypes. Metastatic breast tumors that overexpress ErbB-2 are difficult to treat and generally resistant to trastuzumab. Lapatinib, a dual EGFR/ErbB-2 tyrosine kinase inhibitor, is approved for the treatment of ErbB-2-positive breast cancer that has advanced during or after trastuzumab treatment. However, resistance to lapatinib occurs in cell culture models in vitro. We have recently published that overexpression of ErbB-2 suppresses Notch-1 activity and this is reversed by inhibitors of ErbB-2, trastuzumab or a tyrosine kinase inhibitor. Furthermore, we demonstrated that trastuzumab resistance is reversed when Notch-1 is downregulated by siRNA or when cells are treated with a gamma-secretase inhibitor (MRK-003, GSI). Additionally, in an independent study we showed that GSI also prevented resistance to lapatinib. Since lapatinib is a very potent inhibitor of ErbB-2 tyrosine kinase activity in vitro, we asked whether a combination therapy based on lapatinib and GSI can prevent the resistant phenotype by using a pre-clinical in vivo model. BT474 breast tumor xenografts were generated in athymic mice and randomized to vehicle, GSI, lapatinib, or lapatinib plus a GSI. Tumor size was measured up to 13 weeks with treatments. The xenograft studies using BT474 lapatinib sensitive cells demonstrated that lapatinib treatment alone inhibited tumor growth by 40%. GSI alone had no effect on growth of tumors compared to vehicle control. However, GSI plus lapatinib significantly reduced tumor growth where regression was observed. Tumor histology of lapatinib plus GSI-treated tumors displayed a significant decrease in Ki67, a proliferation marker, and an increase in apoptotic cells as measured by TUNEL. Furthermore, both ERK1/2 and AKT1 phosphorylated proteins were undetectable by western blot in tumors treated with lapatinib plus GSI. These results suggest that both ErbB-2 and Notch activities must be inhibited to induce tumor regression of ErbB-2 positive breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2553. doi:10.1158/1538-7445.AM2011-2553
Abstract 2554: Synergistic antitumor effect of AUY922 in combination with sorafenib in hepatocellular carcinoma cells
Authors: Lau Chi-Keung , Yang Z F. , Ho D W. , Lam C T. , Pang R , Fan S T. , Poon R T.
Published: June 2012

PURPOSE: Molecularly targeted therapy is of particular importance for HCC due to a lack of efficacy with currently approved chemo-toxic therapies. It is of interest to investigate the combined effect of two molecular targeted drugs, sorafenib (a multi-kinase inhibitor with anti-angiogenic, pro-apoptotic and Raf kinase inhibitory activity) and a highly potent non-geldamycin HSP90 inhibitor, NVP-AUY922 on HCC treatment. EXPERIMENTAL DESIGNS: Cell viability after different treatments was measured by both 3,[4,5-dimethylthiazol-2-yl] -2,5-diphenyl-tetrazolium bromide (MTT) assay and cytofluorometric annexin-V apoptotic assay to compare the apoptotic cells induced by single versus combined treatment. Cell cycle analysis was also performed, and Western blotting was employed to determine the effects on MEK signaling, and in vivo efficacy was determined in nude mice with PLC/PRF/5 xenografts. RESULTS: Combined drugs treatment produced a synergistic effect on decreased HCC cell viability shown by MTT assay. An increase in the number of apoptotic cells were observed by apoptotic assay in combined drugs group when compared with single agents sorafenib or NVP-AUY922. Also, sorafenib combined with NVP-AUY922 induced S-phase arrest which was demonstrated by cell cycle analysis. Sorafenib alone decreases phospho-Erk1/2 expression, and this effect was further enhanced in combination treatment with NVP-AUY922. Finally, sorafenib plus NVP-AUY922 significantly suppressed PLC/PRF/5 xenograft tumor growth when compared with single (NVP-AUY922 or Sorafenib) treatment alone. CONCLUSION: The combination therapy of sorafenib and NVP-AUY922 can be a new and promising therapeutic approach to the treatment of HCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2554. doi:10.1158/1538-7445.AM2011-2554
Abstract 2581: Indolequinone mechanism-based inhibitors of quinone reductases: Structural basis for selective inhibition of NQO2 relative to NQO1
Authors: Yan Chao , Dufour Marine , Siegel David , Reigan Philip , Gomez Joe , Shieh Biehuoy , Moody Christopher J. , Ross David
Published: June 2012

There are two quinone reductases that occur in mammalian systems NAD(P)H:quinone oxidoreductase 1 (NQO1, EC 1.6.99.2) and NRH:quinone oxidoreductase 2 (NQO2, EC 1.10.99.2). NQO1 has been shown to be up-regulated in many types of human solid cancer; whereas NQO2 has been shown to be highly expressed in leukemias. In order to explore their potential as therapeutic targets, we have developed potent and selective mechanism-based inhibitors for both enzymes centered on the indolequinone pharmacophore. Previously, we characterized ES936 (5-methoxy-1,2-dimethyl-3-(4-nitrophenoxy)methylindole-4,7-dione) as an efficient mechanism-based inhibitor of NQO1 and we have now developed a series of indolequinones as mechanism-based inhibitors of NQO2. Substitution of the 5-methoxy group in ES936 with an aminoalkylamino side chain generated potent mechanism-based inhibitors of NQO2 that did not efficiently inhibit NQO1. NQO2 inhibition was observed with compounds with 5’-aminoalkyl chains that varied from 3 to 8 carbons in length, with maximal inhibition observed with compounds that possessed 5’-chain lengths of between 3 to 5 carbons. Compounds with substitutions at the 6-position were not efficient mechanism-based inhibitors of NQO2. As previously observed for a series of NQO1 mechanism-based inhibitors, structural requirements for efficient inhibition of NQO2 also included a substituent at the 3-position capable of leaving to generate a reactive iminium electrophile following enzymatic reduction. Selected indolequinones were tested for NQO2 inhibition using the human leukemia cell line K562 and were found to inhibit NQO2 activity in K562 cells at nanomolar concentrations while not affecting NQO1 activity. Computational-based molecular modeling simulations demonstrated the substantial difference between the active site of NQO1 and NQO2 and ESI-LC/MS provided possible explanations for selective enzyme inhibition. These indolequinones represent the first mechanism based inhibitors of NQO2 to be characterized.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2581. doi:10.1158/1538-7445.AM2011-2581
Abstract 2584: eNOS as a therapeutic target in pancreatic cancer
Authors: Barrientos Katharine S. , Lampson Benjamin L. , Kendall Stephan D. , Counter Christopher M.
Published: June 2012

Pancreatic cancer has a very high mortality rate, and frontline therapy has not changed in over a decade indicating a need for novel therapeutics. In this regard, endothelial Nitric Oxide Synthase (eNOS) has emerged as a new target due to recent studies demonstrating elevated expression in human pancreatic cancers, and inhibition of pancreatic tumor growth with eNOS knockdown or knockout in xenograft and genetically engineered mouse models. By pharmacologically testing eNOS inhibition, we found that a non-selective NOS inhibitor, L-NG-Nitroarginine methyl ester (L-NAME), inhibited tumor growth of human pancreatic cancer cell lines and extended survival in the aggressive Pdx-1-CreTg/+;LSL-KRASG12D/+;LSL-Trp5R172H/+ (KPC) mouse model of pancreatic ductal adenocarcinoma (PDAC) by ∼30 days. This extended survival is particularly significant given that the current frontline therapy, gemcitabine, does not provide these mice with a similar survival advantage. While general inhibitors such as L-NAME are attractive molecules to explore, evidence has shown that targeting all three NOS enzymes can have undesirable off-target effects. As eNOS has been identified as the NOS family member required for pancreatic tumorigenesis, and there currently are no selective eNOS inhibitors, we have created and optimized a cell-based system to identify potent and selective compounds for eNOS inhibition. This assay uses a mammalian baculovirus expression system to distinguish the activity of eNOS, nNOS, and iNOS via measurement of the stable bi-products of nitric oxide synthesis, and has been tested with a variety of published NOS inhibitors including L-NAME, the iNOS specific inhibitor 1400W, and the nNOS specific inhibitor L-NPA. The assay is suitable for high throughput screening of small molecule libraries to identify novel eNOS inhibitors that, when paired with gemcitabine, may represent a novel combination therapy for pancreatic cancer therapeutics.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2584. doi:10.1158/1538-7445.AM2011-2584
Abstract 259: Novel peptide directed targeting of EWS-FLI1 impairs tumor cell growth
Authors: Erkizan Hayriye V. , Scher Lauren M. , Gamble Ellen , Barber-Rotenberg Julie , Uren Aykut , Toretsky Jeffrey
Published: June 2012

Introduction: Patients with Ewing's Sarcoma require improved therapy. EWS-FLI1 fusion protein provides a unique targeting opportunity. In the quest for protein partners, we identified a novel peptide sequence that binds to EWS-FLI1 using phage display. We hypothesize that by identifying peptides, and their cognate proteins, we can modulate the function of EWS-FLI1 to improve therapies for ESFT patients. Methods: Secreted peptide-alkaline phosphatase conjugates were used in ELISA for resolving binding regions. Cytotoxicity experiments were analyzed with MTT or WST reduction. Cell cycle analysis were performed using flow cytometry. Results: A phage display experiment to identify EWS-FLI1 peptides resulted in 96 phage clones that demonstrated binding to EWS-FLI1 by ELISA. Those 96 phage clones resulted in sequences that yielded twenty-seven unique peptides. Peptide A1 is one of 27 unique peptides that was commercially synthesized fused to penetratin (16aa) to facilitate intracellular transport. The cytotoxicity of A1 peptide was evaluated in TC32 and TC71 (EWS-FLI1, type I), A4573 (EWS-FLI1, type III), JN-DSRCT (desmoplastic small round blue cell tumor containing EWS-WT1), and SKNAS (a neuroblastoma cell line lacking EWS-FLI1 rearrangement). The IC50 level for A1 is between 5 -15 μM in cell lines bearing EWS fusion proteins. However, it is more than 50 μM in cells without the rearrangement. A1-alkaline phosphatase (A1-AP) conjugates were prepared with alanine substitutions throughout the peptide. Wild-type non-conjugated A1 competed away the interaction between the EWS-FLI1 and A1-AP, confirming its ability to bind to EWS-FLI1. Mutations in A1 demonstrated that the lysine residues are critical for binding to EWS-FLI1. The minimal interacting amino acids were validated using shortened and mutated versions of A1 in both ELISA and cell growth assays, including soft agar. A1 peptide blocked cell cycle progression of synchronized ESFT cells and caused accumulation at S phase. A1 peptide also inhibited EWS-FLI1 dependent transcription. Discussion: The A1 peptide directly binds to the EWS-FLI1 oncoprotein and leads to cell death in cells with either the EWS-FLI1 or EWS-WT1 fusion proteins. While A1 was discovered based on binding to EWS-FLI1; toxicity in JN-DSRCT studies suggest that the A1 peptide may have potency to EWS bearing fusion proteins. These findings present a novel method of targeting EWS rearranged oncoproteins and could lead to novel therapies

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 259. doi:10.1158/1538-7445.AM2011-259
Abstract 2592: Therapeutic testing of a novel inhibitor GAP-107B8 on ovarian cancer cells
Authors: Yan Fu J. , Garson Kenneth , Chabot Jaclyn M. , Vanderhyden Barbara C.
Published: June 2012

Background: Ovarian cancer is the most fatal gynaecologic disease in the western world. In 2010 in the United States, an estimated 21,880 women will develop ovarian cancer and an estimated 13,850 women will succumb to this disease. Current treatments are limited to surgery and chemotherapy, but the disease often recurs highlighting the need for novel cancer therapeutics. We are currently evaluating the efficacy of a novel therapeutic, GAP-107B8 (PharmaGap Inc, Ottawa) using in vitro and in vivo models. GAP-107B8 was designed as a protein kinase C (PKC) inhibitor. The PKC family of serine/threonine kinases are involved in cellular proliferation, differentiation, apoptosis and cell polarity. One PKC isoform, PKC iota, has recently been identified as a human oncogene and has been shown to be overexpressed in epithelial ovarian cancers and is thus a potential therapeutic target for ovarian cancer. Objectives: 1) To test the novel inhibitor GAP-107B8 on ovarian cancer cell lines to determine its effects on cell proliferation, cell cycle progression and apoptosis; and 2) To determine the therapeutic potential of GAP-107B8 in xenograft models of two different ovarian cancer cell lines. Methods: Three ovarian cancer cell lines were treated with three different concentrations of GAP-107B8 and screened using high throughput assays to measure the proliferation of cells in adherent cultures. Apoptosis was measured by TUNEL staining, PARP cleavage and cell cycle analysis. Tumor burden was assessed in mice receiving subcutaneous implants of two ovarian cancer cell lines, followed by daily intra-tumoral injections of GAP-107B8. Results: GAP-107B8 caused a significant reduction in cell proliferation in 3 ovarian cancer cell lines tested (86% to 95%; p<0.001), including a cell line resistant to standard chemotherapy. In vivo, intra-tumoral treatment with GAP-107B8 resulted in a 45% reduction in average tumor size in the A2780cp-derived tumours (n=6/group, p<0.01) and 75% in the HEY-derived tumors (n=3/group, p<0.001). Cell killing may be mediated by apoptosis based on the observation of TUNEL staining 30 hours after treatment of cells in vitro with GAP-107B8. Apoptosis was confirmed by flow cytometry and PARP cleavage. GAP-107B8 also inhibited progression of cells through the cell cycle by blocking or delaying progression of cells through G2/M into the G1 phase.

Conclusion: The novel inhibitor GAP-107B8 displays good efficacy in vitro in suppressing the proliferation of ovarian cancer cell lines. Cytotoxicity may be manifested in perturbations of the cell cyle and induction of apoptosis. Finally, GAP-107B8 showed therapeutic efficacy in ovarian cancer xenograft models.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2592. doi:10.1158/1538-7445.AM2011-2592
Abstract 2597: PLA2G7 associates with aggressive prostate cancer in vivo and regulates prostate cancer cell migration and adhesion in vitro
Authors: Vainio Paula , Hilvo Mika , Vesterinen Tiina , Gupta Santosh , Härmä Ville , Nees Matthias , Turunen Juha P. , Lundin Johan , Rannikko Antti , Orešič Matej , Kallioniemi Olli , Iljin Kristiina
Published: June 2012

There is an urgent need for more efficient and more targeted methods of prostate cancer treatment. We have previously shown PLA2G7 (also known as lipoprotein-associated phospholipase A2, Lp-PLA2) to be a possible biomarker and drug target especially in ERG positive prostate cancers by combining gene expression data from prostate cancer tissues in vivo and functional RNAi studies in vitro. To further study the potential of PLA2G7 in prostate cancer management immunohistochemical staining of 119 clinical prostate cancer samples and 112 adjacent normal prostate samples were performed. In addition, a global lipidomic, eicosanoid and gene expression analysis was utilized to study the effect of PLA2G7 silencing in ERG oncogene positive prostate cancer cells. The results emphasized high expression of PLA2G7 in 66 % of the cancer samples, whereas less than 4 % of the adjacent normal tissues showed positive staining. Furthermore, PLA2G7 expression significantly correlated with high Gleason score. PLA2G7 silencing in vitro induced a reduction in the amount of lysophosphatidyl choline and leukotriene E4, as well as in the expression of multiple genes and signaling pathways involved in cell adhesion and motility. In accordance, knock-down of PLA2G7 in 3D prostate cancer cell culture model lead to decreased invasion to extracellular matrix. Interestingly, PLA2G7 silencing also reduced the expression of ALDH1A1, a marker for malignant prostate stem cells and predictor of poor prostate cancer outcome. In conclusion, these novel findings suggest an oncogenic role for PLA2G7 in aggressive prostate cancers and support the rationale for PLA2G7 targeted therapy in these cancers. A novel PLA2G7 inhibitor is currently under clinical evaluation for cardiovascular diseases, presenting thus an interesting opportunity for drug repositioning to other indications, such as prostate cancer. In addition, lipid-lowering statins are known to lower PLA2G7 mass and activity, therefore PLA2G7 may also represent a target of lipid-lowering therapy in reducing the risk of aggressive prostate cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2597. doi:10.1158/1538-7445.AM2011-2597
Abstract 2601: ROCK1 as a potential therapeutic target in pancreatic cancer
Authors: Whatcott Clifford , Watanabe Aprill , Demirjian Joseph , Barrett Michael , Hostetter Galen , Hoff Daniel Von , Han Haiyong
Published: June 2012

ROCK1, or Rho-associated coiled coil-containing protein kinase 1, is a multifunctional member of the AGC (protein kinase A/G/C) kinase family that has been implicated in the modulation of stress-fiber assembly, cell-cell adhesion, cell contraction, apoptosis, cytokinesis, and in the migration and invasion of multiple cell types. Increased ROCK1 expression has been observed in a number of pathological conditions, including cancer. We identified a low frequency (4/34) amplification of the ROCK1 gene locus at chromosome 18q11.1 in pancreatic ductal adenocarcinoma (PDA) patient tissue samples by aCGH analysis. We therefore hypothesized that ROCK1 might play an important role in pancreatic cancer progression, and may serve as a suitable target in pancreatic cancer treatment. Consistent with findings in other tumor types, we observed increased expression of ROCK1 in pancreatic epithelial cells relative to the surrounding stromal cells, or adjacent normal pancreatic ductal cells, in an immunohistochemical (IHC) analysis of a pancreatic cancer tissue array. In our study, 76% (53/70) of tumor samples exhibited 2+ or greater (scale 0-3+) in staining intensity by IHC analysis, versus 40% (19/47) of adjacent normal tissue samples (P<0.0001). This same increased expression of ROCK1 in cancer cells was also observed in a coculture model of human PDA cells and primary myofibroblast cells derived from PDA tissues. Inhibition of ROCK kinase activity by small molecule inhibitors (Fasudil and Y27632) demonstrated moderate (IC50s range from 2-30 μM) inhibition of PDA cell proliferation. An increased sensitivity to ROCK1 inhibition was observed in PDA myofibroblasts, which corresponded with a decreased expression of Collagen I. These results suggest that ROCK1 may play a role in pancreatic cancer, both in the proliferation of tumor epithelial cells, as well as the development of the stromal compartment. Based on these findings we feel that ROCK1 is a potential therapeutic target in both the tumor and stromal cells in pancreatic cancer, and may provide an effective means to enhance current treatment regimens.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2601. doi:10.1158/1538-7445.AM2011-2601
Abstract 2604: PENAO: A novel tumor metabolism inhibitor for glioblastoma
Authors: Chung Sylvia A. , Dilda Pierre J. , Ramsay Emma E. , Teo Charlie , Hogg Philip J. , McDonald Kerrie L.
Published: June 2012

Despite undeniable progress in the care and the treatment of primary brain tumors, for most patients diagnosed with glioblastoma (GBM) there is no realistic possibility of cure or even long term survival. Inherent resistance to conventional chemotherapy and irradiation are characteristic of GBM. Testing of new potential anti-tumorigenic drugs is needed. PENAO, (4-(N-(S-penicillaminylacetyl)amino)phenylarsonous acid) is a mitochondrial toxin that inactivates inner-membrane adenine nucleotide translocase (ANT) resulting in proliferation arrest and apoptosis of tumor and tumor-supporting cells. The cytostatic efficacy of PENAO was tested on a panel of five commercial and primary GBM cell lines that differed in tumorigenicity, drug resistance, invasion and DNA repair. PENAO demonstrated an impressive anti-proliferative activity compared to carboplatin and temozolomide, drugs commonly used to treat GBM patients. The half maximal inhibitory concentration (IC50) values for PENAO were all in the low micromolar range. The increase in anti-proliferative activity for PENAO compared to carboplatin ranged from 6 to 200-fold. PENAO is a substrate for the multidrug resistant associated proteins 1 and 2 and inhibition of this transporter enhanced PENAO anti-proliferative activity from 2 to 8-fold. In conclusion, PENAO is a potent inhibitor of GBM cell line proliferation. This activity was superior to that observed with standard chemotherapeutics and warrants further in vivo investigations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2604. doi:10.1158/1538-7445.AM2011-2604
Abstract 2612: Effective targeting triple negative breast cancer cells by a novel oral heat shock protein 90 inhibitor PF-4942847
Authors: Mehta Pramod P. , Whalen Pamela , Kung Pei-Pei , Yamazaki Shinji , Gehring Michael R. , Yin Min-Jean
Published: June 2012

Triple negative breast cancer (TNBC) patients have poor prognosis and survival that the development of new targeted therapies for TNBC is strongly demanded. Genes associated with high proliferation and aggressive tumor progression, such as PI3K/PTEN aberration, EGFR overexpression, and cell cycle upregulation, play important roles in triple negative breast cancer. The molecular chaperone heat shock protein 90 (Hsp90) is required for the conformational maturation and stability of a variety of key signaling proteins, such as EGFR, AKT, Raf, p53, and cdk4, in addition to many others. Therefore, an Hsp90 inhibitor may present therapeutic benefits on TNBC via the inhibition of EGFR, AKT/PI3K pathway, and cell cycle progression. In this study, we describe a novel oral Hsp90 inhibitor, PF-4942847, which induces apoptosis and cell cycle block, as well as inhibits cell proliferation in TNBC cells through protein degradation in EGFR, cMet, AKT, and pERK. PF-4942847 exhibits excellent oral bioavailability in mice and effectively induces Hsp90 client protein degradation in MDA-MB-231 xenograft tumors, and subsequently abolishes the in vivo tumor growth of MDA-MB-231 in the xenograft model. Moreover, correlation of AKT degradation and Hsp70 induction in host peripheral blood lymphocytes (PBLs) and xenograft tumors was determined and reveals a differential target modulation dynamic between Hsp90 client proteins in different tissue compartments. These data implicate AKT degradation in PBLs as a possible biomarker of tumor progression for future clinical development. In summary, our results demonstrate PF-4942847 is a potent oral Hsp90 inhibitor and is a candidate for clinical development in triple negative breast cancer by collaboratively targeting multiple signaling pathways.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2612. doi:10.1158/1538-7445.AM2011-2612
Abstract 2618: DNMT1 as a marker of differential sensitivities to epigenetic therapy of a Kras mutant and Kras wild type human non small cell lung cancer cell line
Authors: Du Zhenzong , Wrangle John , Pelosky Kristen , Harris James , Shin James , Vendetti Frank , Hulbert Alicia , Lee Beverley , Zahnow Cyntia , Ahuja Nita , Herman James , Baylin Stephen , Brock Malcolm
Published: June 2012

INTRODUCTION: Epigenetic therapy with a demethylating agent and an histone deacetylase inhibitor (HDACi) is now being pursued in hematological as well as solid tumor malignancies. Clinical responses have been varied with complete responses in some patients and no efficacy of the drugs in others. We investigated the effect of this therapy on two targets, DNA methyltransferase1 (DNMT1) and H3K4 modified histones, respectively.

METHODS: Two human lung adenocarcinoma cell lines, A549 (Kras mutant) and H838 (Kras wild type) were pre-exposed for 72 hours with daily treatment of 500nM azacitidine alone or 72 hours of daily 500nM azacitidine followed subsequently with 10 nM, 100nM, 1000nM entinostat at 96 hours. DNMT1 and H3K4 protein levels were assayed by Western blot analysis at various time points after treatment. Cells were also re-plated after treatment to assess differential growth characteristics.

RESULTS: In vitro growth of H838 cells is sensitive to azacitidine alone and in combination with entinostat whereas growth of the A549 cell line is only sensitive to azacitidine and entinostat in combination. Treatment with azacitidine, severely depleted DNMT1 protein expression in H838 cells both when given alone and in combination with most dose levels of entinostat. This decrease was transient and within 4 days, the protein was fully replenished. Azacitidine alone did not cause an appreciable decrease in DNMT1 protein expression of A549 cells but, when combined with increasing levels of entinostat, DNMT1 levels were significantly depleted and did not replenish for 7 days. Re-plating after treatment showed growth inhibition versus mock of all regimens containing azacitidine in the H838 cell line only whereas growth inhibition in the A549 cells was observed only in the combinatory therapy arms. Furthermore, in the A549 cell line, H3K4 protein levels (a marker of active gene expression) peaked at 7 days after treatment versus a peak in the first 24 hours in the H838 cell line.

CONCLUSIONS: Differing sensitivities to epigenetic therapy in lung adenocarcinoma cell lines may reflect underlying differences in molecular phenotypes. Large decreases in DNMT1 expression are associated with sensitivity to azacitidine. In a cell line insensitive to azacidine alone, the addition of entinostat may accentuate DNMT1 protein depletion and delay its reexpression. This effect on DNMT1 may render this latter cancer cell line more sensitive to epigenetic therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2618. doi:10.1158/1538-7445.AM2011-2618
Abstract 2622: CIP2A mediates the apoptotic effect of bortezomib on triple negative breast cancer cells
Authors: Tseng Ling-Min , Liu Chun-Yu , Chang Kung-Chi , Shiau Chung-Wai , Cheng Ann-Lii , Kuo Hsin-Yu , Tzeng Cheng-Hwai , Chen Kuen-Feng
Published: June 2012

Background: Triple negative breast cancer (TNBC) is with aggressive behaviors and poor prognosis because of the absence of a specific target for the tumor, such as in endocrine therapy and anti-HER2 therapy. Bortezomib, a proteasome inhibitor, may exert potential efficacy in TNBC through its multiple cellular effects. Our previous study has shown that CIP2A, cancerous inhibitor of PP2A, mediates effects of bortezomib on phospho-Akt (P-Akt) and apoptosis in hepatocellular carcinoma. (Oncogene, 2010). Here, we tested efficacy of bortezomib to TNBC and examined the drug mechanism. Methods: Triple negative breast cancer cell lines were used for in vitro studies. Apoptosis was examined by both flow cytometry and Western blot. Signal transduction pathways in cells were assessed by Western Blot. Gene silencing was done by small interference RNA (siRNA). In vivo efficacy of bortezomib was tested in nude mice with breast cancer xenografts. Results: Bortezomib induced apoptosis in association with down-regulation of CIP2A and P-Akt in a dose- and time-dependent manner in three TNBC cells lines (HCC-1937, MDA MB-468, MDA MB-231) but not in hormone positive MCF-7 cells. Over-expression of CIP2A in MDA MB-231 cells protected cells from bortezomib-induced apoptosis, and down-regulation of CIP2A by siRNA overcame the apoptotic resistance to bortezomib in MCF-7 cells. These data indicate that inhibiton of CIP2A determined the sensitivity of bortezomib to breast cancer cells. Importantly, bortezomib showed in vivo efficacy in HCC-1937 xenografted tumor. Conclusions: CIP2A mediates bortezomib-induced apoptosis in TNBC. Targeting CIP2A-PP2A-P-Akt signaling pathway is a novel approach for the treatment of TNBC. Supported by VGHTPE 100DHA0100591 and V99C1-059.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2622. doi:10.1158/1538-7445.AM2011-2622