bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract C152: Mechanisms of KRAS dependency in pancreatic ductal adenocarcinoma.
Authors: Hayes Tikvah K. , Der Channing J.
Published: June 2012

Currently, pancreatic ductal adenocarcinoma (PDAC) has a dismal <5% survival rate two years after initial diagnosis. Despite significant advances in development of signal transduction targeted therapies for some cancers, erlotinib, an EGFR inhibitor, in combination with gemcitabine, is the only targeted drug approved for treatment of PDAC. The frequency of KRAS oncogene mutations in PDAC is greater than 90%, thus inhibition of K-Ras4B protein function may have a significant impact on PDAC tumorigenesis. In support of this hypothesis, several recent studies demonstrated that KRAS mutant cancer cell lines display a strong dependence or addiction to mutant K-Ras for survival. Surprisingly, K-Ras addiction was not attributed to either the Raf or phosphoinositide 3-kinase (PI3K) effector pathways, which are two of the best-characterized Ras signaling effectors. These results suggest that other pathways are key for mutant KRAS dependency. Elucidating the effector mechanism(s) necessary for KRAS addiction may implicate signaling pathways, which harbor novel therapeutic targets for future anti-K-Ras drug development. To address this question, we first verified that shRNA silencing of mutant KRAS in a panel of pancreatic cell lines led to a strong reduction in anchorage-independent growth. Notably and in contrast to published studies, this was not due to decreased cell survival or increased anoikis. Using KRAS mutant PDAC cell lines, we purpose to use effector domain mutants of oncogenic K-Ras4B that are differentially impaired in effector interaction and constitutively activated effectors to define the key effector(s) involved in KRAS dependency. These studies will help to define key signaling activities of mutant KRAS that are critical for oncogenesis in PDAC.

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 C152.
Abstract C162: Influence of tumor genotype on aflibercept (VEGF Trap) antitumor activity in preclinical tumors.
Authors: Valence Sandrine , Guerif Stephane , Jouannot Erwan , Vrignaud Patricia , Vincent Loic , Dib Colette , Chiron Marielle
Published: June 2012

Aflibercept (also called VEGF Trap) is a novel anti-angiogenic agent currently tested in combination with standard chemotherapy in several phase 3 clinical trials including second-line metastatic colorectal cancer. It is a recombinant fusion protein consisting of Vascular Endothelial Growth Factor (VEGF)-binding portions from the extracellular domains of human VEGF Receptors 1 and 2 fused to the Fc portion of the human IgG1. Aflibercept acts as a soluble decoy receptor that binds to VEGF-A, with high affinity, as well as the related ligands PIGF and VEGF-B. It neutralizes all isoforms of VEGF-A, blocks angiogenesis and effectively suppresses tumor growth in vivo. Aflibercept also binds Placental Growth Factor (P1GF), which has been involved in pathological angiogenesis and tumor progression.

Preclinical studies were performed to assess the influence of somatic mutations on the activity of aflibercept against the growth of 37 human tumor xenografts in mice covering 17 different indications. These models were previously documented for KRAS, BRAF, and PIK3CA activating mutations and PTEN protein deficiency according to the Catalogue of Somatic Mutations in Cancer (COSMIC) database, literature, and internal studies. Aflibercept was administered twice weekly at 40 mg/kg. Aflibercept was found highly active in 6 models with tumor growth inhibition (ΔT/ΔC) ≤ 0%, very active in 9 models (ΔT/ΔC 0–10%), displayed some activity in 17 models (ΔT/ΔC 10–40%), and had no effect in 5 xenograft models (ΔT/ΔC > 40%). We stratified the models into two groups according to the tumor response: the “partially reponsive and non-responsive models” with detectable tumor growth under treatment (22/37 models), and the “responsive models” with no detectable tumor growth or regression under treatment (15/37 models). Mutations in KRAS (G12D/V/S, G13D, Q61H) were present in both responsive (3 models) and partially responsive/non-responsive models (4 models). Ten of 28 (36%) KRAS wild-type tumors and 3 of 7 (43%) KRAS mutated tumors were responsive to aflibercept indicating that KRAS status has no significant influence on aflibercept activity on tumors (p=1; Fisher exact test). Similarly, tumor models were also found sensitive to the anti-tumor effects of aflibercept whatever the BRAF and PIK3CA genotype status, and PTEN protein expression status.

In summary, the status of KRAS, BRAF, PIK3CA and PTEN in these preclinical tumor models did not significantly influence the response to aflibercept. The impact of these genetic alterations on aflibercept activity will be further explored in clinical trials.

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 C162.
Abstract C170: The combination of statins and dipyridamole is effective preclinically in AML, MM, and breast cancer.
Authors: Pandyra Aleksandra , Sobol Paul , Sharmeen Sumaiya , Schimmer Aaron , Penn Linda
Published: June 2012

Statins are drugs that have been utilized for years to treat hyperlipidemia through inhibition of the rate-limiting enzyme of the mevalonate (MVA) pathway, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR). Preclinical evidence has demonstrated statins to possess anti-cancer properties against a wide range of tumors but not normal cells. Through the use of a chemical library screen, we hypothesize that the identification of compounds which potentiate the anti-cancer effects of statins will uncover novel molecular pathways and/or targets that can be exploited in combination with the MVA pathway to maximize tumor cell death.

A pilot 100-compound library, composed of off-patent pharmacologically active drugs clinically used for a wide spectrum of diseases was screened in the multiple myeloma (MM) KMS11 cell line. Dipyridamole (DP), a commonly prescribed anti-platelet agent potentiated the anti-cancer effects of atorvastatin. The DP-statin combination was synergistic and capable of inducing apoptosis in a variety of acute myelogenous leukemia (AML), MM and breast cancer cell lines. The DP-statin combination also induced apoptosis in primary AML patient samples, but was not toxic to normal PBSCs. In an in vivo AML tumor model, the DP-statin combination was found to be effective at inhibiting tumor growth.

DP is known to elicit numerous effects, amongst them, phosphodiesterase (PDE) inhibition. In AML cell lines, activators of the PKA pathway including other PDE inhibitors, also induced apoptosis in combination with statins similar to DP. Interestingly, the DP-statin combination prevented the increase of HMGCR, which occurs following statin treatment as part of a classic feedback response. Further mechanistic investigations to determine how DP potentiates statin-induced apoptosis are underway. As both statins and DP are pre-approved for use in humans, off-patent, and readily available, they have the potential to directly impact patient care.

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 C170.
Abstract C174: Integrated real-time photoacoustic diagnostic imaging and therapeutics of oral cancer cells via gold nanorod conjugate.
Authors: Wu Ping-Ching , Shieh Dar-Bin , Tsai Tsung-Lin
Published: June 2012

Cancer therapy is still a grand challenge due to their aggressive invasion and metastasis to adjacent tissues and distant organs. Only few reported integrated approaches capable of for simultaneous diagnosis and therapy. In this study, gold nanorods (AuNR) were synthesized to construct a novel theranostics platform. The characteristic tunable surface plasmon bands in the near-infrared region (800 nm) enabled efficient tissue penetration of the NIR activation light source. PEG and Her2 antibodies were conjugated on the AuNR for targeting oral cancer cells while present adequate biological stealth. The specific in vivo targeting and biodistribution of the AuNR800-PEG5K-Her2 were evaluated in mice implanted with tumor cells over-expression of Her2 by atomic absorption spectroscopy. Molecular photoacoustic imaging was performed using a hydrophone transducer containing a tunable pulsed laser system. A maximum signal of 4.2 dB was recorded within the tumor site 12 hours after injection. Moreover, AuNRs conjugated with Her2 antibodies significantly reduced non-specific liver and spleen uptake compared to AuNRs lacking the antibodies. For the evaluation of therapeutic efficacy, solid-state C.W. lasers at 808nm peak wavelength were established to scan the tumor lesions for laser induced hyperthermia. A significant increase in the tumor local temperature was observed in tumor-bearing mice injected with AuNRs conjugated with HER2 antibodies compared to PBS and AuNR control groups. Furthermore, AuNR800-PEG5K-Her2 treated mice exhibited an improved overall survival compared to the control groups.

In conclusion, we successfully demonstrate an integrated system capable of real-time photoacoustic imaging of the tumor lesions and perform laser induced hyperthermia therapy using AuNR800-PEG5K-Her2 as the probe and NIR laser as the light source.

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 C174.
Abstract C180: The effect of JS-K, a lead O2-arylated diazeniumdiolate anticancer agent, on the cellular glutathione status.
Authors: Holland Ryan J. , Maciag Anna E. , Rodriguez Luis G. , Saavedra Joseph E. , Keffer Larry K. , Shami Paul J.
Published: June 2012

JS-K is an O2-arylated diazeniumdiolate prodrug which has demonstrated pronounced selective cytotoxicity and antitumorigenic properties in a variety of cancer models both in vitro and in vivo. Mass spectrometric studies of the metabolic fate of JS-K were undertaken to understand the origin of the cytotoxicity. Consistent with model chemical reactions, the first step in the cellular metabolism of JS-K is the de-arylation of the diazeniumdiolate by glutathione (GSH) via a nucleophilic aromatic substitution reaction, forming a dinitrophenyl-GSH adduct, with the daizeniumdiolate ion by-product ultimately releasing nitric oxide (NO). A consequence of this metabolism and NO-generation is a rapid and pronounced depletion of cellular GSH concurrent with a rise in oxidized glutathione (GSSG). The GSH/GSSG redox couple, considered to be the major redox buffer of the cell, helps maintain a reducing environment under basal conditions. The depletion of GSH through drug conjugation and subsequent oxidation results in a rapid rise in the oxidation potential of the cellular environment, an increase of 30 mV in the first 30 min of treatment, initiating the stress signaling pathways which lead to extrinsic/intrinsic apoptosis. Preventing this rise in the oxidation potential by pre-treating cells with known antioxidant N-acetylcysteine inhibited the downstream signaling events leading to apoptosis. These data indicate that depletion of the glutathione pool is a crucial first step in the mechanism of JS-K cytotoxicity.

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 C180.
Abstract C181: The combination of BKM120, a PI3K inhibitor, with panobinostat synergistically inhibited proliferation and induced apoptosis in lymphoma cells.
Authors: Bodo Juraj , Durkin Lisa , Hill Brian T. , Hsi Eric D.
Published: June 2012

Combination therapies may help to decrease toxicity by allowing use of lower concentrations of individual agents to get a similar biologic effect and/or overcoming clinical resistance to single agent therapy. Recently, we have shown that by the inhibition of PKCβ, a protein kinase increasing survival and proliferation signals, we can shift the balance toward histone deacetylase inhibitor (HDI) induced stress response and the irreversible engagement of the apoptotic cascade in lymphoma cells. In the present study, we investigated the cytotoxicity and mechanisms of cell death of combination of BKM120, a PI3k inhibitor with panobinostat (LBH589), a histone deacetylase inhibitor in B-cell and T-cell lymphoma cell lines.

Flow cytometry assays and PARP cleavage analysis were applied for the study of the apoptosis induction. Cellular protein levels were measured by Western blot. Cytotoxicity of single agents and their combinations was determined by WST-1 proliferation assay. The interaction between BKM120 and panobinostat was examined according to the Chou and Talalay method by using the Calcusyn software.

Combined BKM120/panobinostat treatment synergistically inhibited proliferation and induced apoptosis in tested cell lines. Panobinostat single treatment (concentrations used in combined treatment) induced a slight proliferation inhibition and apoptosis. Interestingly, this treatment increased the level of phosphorylated AKT that might result in an attenuation of further apoptosis. The elevated AKT phosphorylation was significantly diminished by simultaneous treatment with BKM120, which may explain increased induction of apoptosis and inhibition of proliferation in cells treated by BKM120/panobinostat. Moreover, in comparison to the effects of single agent treatments, combined BKM120/panobinostat treatment resulted in significantly lower phospho-RPS6, phospho-GSK3 and p21 protein levels and an increased level of acetylated histone H3.

Our data suggest that PI3k inhibitors in combination with HDI might have potential therapeutic value in lymphoma treatment. The inhibition of PI3k by BKM120 markedly sensitized lymphoma cells to the induction of apoptosis by panobinostat and synergistically inhibited the proliferation of all tested lymphoma cell lines. However, the molecular events underlying the synergistic effect using PI3k inhibitors in combination with HDI remain to be fully elucidated.

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 C181.
Abstract C203: Combined treatment of MK2206 (AKTi) and AZD6224 (MEKi) shows activity in triple-negative breast cancer cell line.
Authors: Soliman Hatem , Noyes David , Cubitt Chris , Lush Richard , Antonia Scott , Sullivan Dan
Published: June 2012

Background: Subsets of triple negative breast cancer (TNBC) such basal have activated signaling through the MAPK-ERK kinase (MEK) pathway. Use of MEK inhibitors in preclinical TNBC models demonstrates some cytostatic activity, but compensatory signaling through the PI3K/AKT pathway diminishes the antitumor effect of MEK inhibitor monotherapy in some TNBC cell lines. Combining a MEK inhibitor with an AKT inhibitor (horizontal blockade) may show increased antitumor activity. We sought to characterize the in vitro effects of the MEK inhibitor AZD6224 combined with the AKT inhibitor MK2206 in three different breast cancer cell lines.

Methods: Cell Titer-Blue cell viability experiments were performed to test dilutions of AZD-6244 or MK-2206 alone or in combination at various molar ratios over a 72 hour time period in MCF-7 (ER+), SKBR3 (HER2+), and MBA-231 (TNBC) cell lines. Synergy was evaluated using Chou and Talalay combination index (CI) analyses (effective dose levels of 0.75, 0.9 and 0.95). Evaluation of MEK and AKT activity in the untreated, AZD6224, MK2206, and AZD+MK treated cells was performed using a BioRad (Hercules, CA) Bio-plex p-ERK1/2 (Thr202/Tyr204, Thr185/Tyr187) + pAKT (Ser473) phosphoprotein assay on a Luminex100.

Results: Synergy was seen only in MDA-231 cells with a mean CI of .492 at a fixed dose ratio of 1:8. The mean fluorescence levels with standard errors of pERK1/2 and pAKT from duplicate experiments are shown in Table 1 in the four treatment groups. The greatest level of baseline MEK activation was seen in the MBA-231 cell line. A significant compensatory increase in p-AKT levels in the MBA-231 cells treated with AZD6224 alone was not observed, but this was seen in the SKBR3 cells.

Conclusions: The combination of AZD6224+MK2206 demonstrates enhanced antitumor activity in the TNBC MBA-231 cell line over AZD6224 monotherapy. The strategy of combining a MEK inhibitor with an AKT inhibitor should be further explored in the treatment of TNBC.

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 C203.
Abstract C204: Potentiation of the novel topoisomerase I inhibitor indenoisoquinoline LMP-400 by the Chk1/2 inhibitor, AZD7762.
Authors: Aris Sheena M. , Pommier Yves G.
Published: June 2012

Novel topoisomerase I (Top1) inhibitors are in clinical development to circumvent the drawbacks of camptothecins (1–3). Here we report molecular investigations of the clinical indenoisoquinoline Top1 inhibitor, LMP-400 by itself and in combination with the cell cycle checkpoint inhibitor, AZD7762 (4). Drug effects on DNA replication and killing of cancer cells were examined. LMP-400 shows synergistic antiproliferative activity when combined with AZD7762 in human colon carcinoma HT-29 and HCT-15 cells. Inhibition of S-phase progression and bromodeoxyuridine incorporation was similarly induced by LMP-400 and CPT and was abrogated by AZD7762. Replication studied by single DNA molecule analyses and immunofluorescence microscopy (molecular combing) (5) showed rapid inhibition of fork progression in response to LMP-400 treatment with subsequent recapitulation after AZD7762 addition. Consistent with cell cycle checkpoint abrogation, AZD7762 inhibited both the activation of Chk1 and Chk2 autophosphorylations in LMP-400-treated cells. In spite of the potent dual inhibition of Chk1 and Chk2 at nanomolar concentrations of AZD7762, cell cycle inhibition and synergism with LMP-400 were only observed at higher concentrations and independently of Chk2 both in Chk2-complemented HT-15 and Chk2 knockout HCT-116 cells. Our study demonstrates the rationale for combining checkpoint kinase inhibitors and the novel non-camptothecin indenoisoquinoline inhibitors.

References:

1. Pommier Y, Cushman M. The indenoisoquinoline noncamptothecin topoisomerase I inhibitors: update and perspectives. Mol Cancer Ther 2009; 8: 1008–14.

2. Pommier Y, Leo E, Zhang H, Marchand C. DNA topoisomerases and their poisoning by anticancer and antibacterial drugs. Chem Biol 2010; 17: 421–33.

3. Teicher BA. Next generation topoisomerase I inhibitors: Rationale and biomarker strategies. Biochem Pharmacol 2008; 75: 1262–71.

4. McNeely S, Conti C, Sheikh T, et al. Chk1 inhibition after replicative stress activates a double strand break response mediated by ATM and DNA-dependent protein kinase. Cell Cycle 2010; 9: 995–1004.

5. Conti C, Seiler J, Pommier Y. The Mammalian DNA Replication Elongation Checkpoint: Implication of Chk1 and Relationship with Origin Firing as Determined by Single DNA Molecule and Single Cell Analyses. Cell Cycle 2007; 6: 2760–7.

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 C204.
Abstract C225: Differential regulation of simultaneous antitumor and alloreactive CD8+ T cell responses in the same host by rapamycin.
Authors: Vareki Saman Maleki , Harding Martha , Waithman Jason , Zanker Damien , Shivji Adil , Rytelewski Mateusz , Mazzuca Delfina , Yekta Maryam , Chen Weisan , Schell Todd , Haeryfar S.M. Mansour
Published: June 2012

Rapamycin is an immunosuppressive agent routinely used in organ transplantation, but also paradoxically, exerts antiviral and anti-tumor activities. Pathogen-specific memory CD8+ T cell (TCD8) responses were recently found to be augmented by rapamycin. However, whether rapamycin influences the magnitude and quality of anticancer TCD8 responses is unknown. Importantly, how rapamycin may regulate simultaneous virus/tumor-specific and alloreactive TCD8 in the same host remains unexplored. To answer these questions, we primed wild-type mice with allogeneic cells concomitantly expressing simian virus 40 large tumor antigen (T Ag), a viral oncoprotein with well-defined epitopes. Rapamycin selectively improved the cross-priming of TCD8 specific for T Ag's most immunodominant epitope called site IV. Rapamycin-treated mice also had a high percentage of splenic CD127highKLRG1low TCD8 as well as an increased frequency of site IV-specific T cells long after the peak of their primary response. When site IV was presented as a cytosolic minigene encoded by a recombinant vaccinia virus, rapamycin failed to enhance the site IV-specific response. Therefore, the nature and presentation mode of antigen determine the susceptibility to the adjuvant effect of rapamycin. Our findings reveal the unexpected benefit of rapamycin treatment in recipients of allografts co-expressing tumor/viral Ags.

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 C225.
Abstract C227: Blockade of tumor-infiltrating myeloid cells by inhibiting CSF-1 receptor overcomes tumor recurrence after radiation therapy.
Authors: Xu Jingying , Escamilla Jemima , McBride William , Wu Lily
Published: June 2012

Radiotherapy is one of the major frontline treatments for prostate cancer (PCa). However, a large proportion of patients suffer from tumor recurrence after radiotherapy. Tumor-infiltrating myeloid cells (TIMs), including CD11b+F4/80+ tumor-associated macrophages (TAM) and CD11b+Gr-1+ myeloid-derived suppressive cells (MDSCs), play critical roles in promoting tumoral angiogenesis, tissue remodeling and immunosuppression. Recently several reports suggested that TIMs might play a critical role in mediating tumor regrowth after radiation therapy. Here, we showed that there is enhanced recruitment of both TAMs and MDSCs after 5 days of 3 Gy radiation treatment in subcutaneously implanted RM-1 syngeneic PCa model. Infiltration of two MDSC subsets, CD11b+Gr-1loLy6Chi mononuclear-MDSC (MO-MDSC) and CD11b+Gr-1hiLy6Clo polymorphnuclear-MDSC (PMN-MDSC), are both increased. Although treatment is localized to the tumor site, the effects of radiation are systematic. Dramatic increases of MDSCs and TAMs were also observed in the spleen, lymph nodes and peripheral blood. To better understand the mechanism of enhanced recruitment of myeloid cells to tumors, we performed RT-PCR analysis on tumor tissues for commonly known factors that mediate the recruitment of myeloid cells. Indeed, we found that macrophage colony stimulating factor 1 (M-CSF-1 or CSF-1) increases by 2 fold in irradiated tumors compared to non-irradiated tumors. In vitro migration assays using conditioned medium from irradiated tumor cells increases migration of RAW246.7 macrophages by 4 fold, and this increase is completely blocked by the very selective CSF1R inhibitor, GW2580.

Immunohistochemical analysis confirmed the induction of TAMs and MDSC recruitment to tumors, and the effectiveness of GW2580 in blocking their infiltration. Most importantly, combination therapy using GW2580 with radiation synergistically suppressed tumor growth and recurrence. This data highlights the importance of CSF1/CSF1R signaling in the recruitment of TIMs post-radiation treatment and their significant role in promoting tumor re-growth. Moreover, our data could potentially provide a more effective and durable treatment strategy for PCa patients.

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 C227.
Abstract C239: Progesterone receptor B through Sp1 induces the phosphatase and tensin homologue deleted from chromosome 10 (PTEN) gene promoter activity and cell death in breast cancer cell lines.
Authors: de Amicis Francesca , Guido Carmela , Santoro Marta , Avena Paola , Panza Salvatore , And Sebastiano , Aquila Saveria
Published: June 2012

Phosphatase and tensin homolog on chromosome 10 (PTEN) is a tumor suppressor attracting considerable attention as new target for effective therapeutic strategies in breast cancer. While recent studies suggest the down-regulation of PTEN by Estrogen Receptor alpha, the role of Progesterone Receptor (PR) is not clearly established.

In the present study we report that PR produces a significant inhibition of MCF-7 breast cancer cell survival with a concomitant increase of PTEN protein, mRNA and gene promoter activity. On the contrary PRs failed to enhance the transcriptional activity of the PTEN promoter lacking the region between −1398 bp to −1118 bp. By analyzing this DNA sequence to search potential binding sites for transcription factors, we observed that this region contains several DNA motifs known to bind the transcription factors Sp1that has been shown to interact with PRs, activating specific gene transcription. In our experimental conditions mithramycin, prevented the PTEN promoter transactivation on OHPg treatment. ChIP analyses showed specific recruitment of PR, Sp1 and RNA polymerase II upon progesterone treatment at PTEN promoter. The persistence of such effects in T47 cells which express high PR levels, addresses how PR/PTEN signalling may be considered as useful pharmacological tool to be exploited for innovative adjuvant strategies in breast cancer treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C239.
Abstract C31: Derivatives of 3a-aza-cyclopenta[a]indene effectively suppress the growth of P-glycoprotein overexpressing cells in in vitro and in vivo systems.
Authors: Lee Te-Chang , Lee Pei-Chih , Kakadiya Rajesh , Su Tsann-Long
Published: June 2012

We synthesized several novel bifunctional alkylating derivatives of 3a-aza-cyclopenta[a]indene (BO-1012, BO-1005, BO-1099, and BO-1101), which are potent DNA interstrand crosslinking agents. In in vitro cytotoxicity assay, these compounds were more cytotoxic to multidrug resistant (MDR) cells, such as KBvin10, KBtax50, and CEM/VBL, than their parental cells. Using a xenograft model, BO-1012, at a dose of 5 mg/kg, partially suppressed the growth of parental KB cells but completely suppressed the growth of KBvin10 cells in nude mice. In exploring the possible mechanism, we found that DNA double-strand break (DSB) repair activity in MDR cells, KBvin10 and CEM/VBL, was significantly reduced compared to their parental cells, KB and CEM. Reduced DSB repair activity in KBvin10 cells was likely due to a defect in nuclear translocation of DNA-PK, a component of the non-homologous end-joining repair machinery. Furthermore, BO-1012-induced DNA-PK translocation from the cytosol into the nucleus in KB cells is associated with activation of the Src/nuclear EGFR cascade, which is defective in MDR cells. Since knockdown of P-glycoprotein (P-gp) by siRNA reactivated the Src/nuclear EGFR cascade, DNA-PK translocation, and DNA repair activity in MDR cells, overexpression of P-gp attenuates the activity of DNA DSB repair via suppression of SRc/nuclear EGFR cascade. Therefore, DNA interstrand crosslinking agents may have potential therapeutic use against P-gp-overexpressing MDR 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 C31.
Abstract C36: Hypoxia or glutathione depletion increase apoptotic response to PRIMA-1 in p53-mutated and nonmutated human breast cancer cells.
Authors: Rieber Manuel , Rieber Mary Strasberg
Published: June 2012

Background: Hypoxia, dysfunction of the p53 tumor suppressor gene product, and intracellular glutathione levels are important in modulating resistance of solid tumors to chemotherapy. PRIMA-1 (bis(hydroxymethyl-3-quinuclidinone) and its structural analog PRIMA-1met are used to reactivate mutant p53 and induce tumor cell apoptosis. However, PRIMA-1met as a single agent was reportedly ineffective in lowering clonogenic survival of (mut p53) DU145 prostate cancer cells, under hypoxia.

Purpose: Here, we investigated whether the toxicity of PRIMA-1 (p53 reactivation and induction of massive apoptosis) is influenced by hypoxia in matched human breast cancer cells with unequal p53 genotype, and by agents that decrease glutathione levels in matched wt p53 human breast cancer cells with different Mn-SOD expression.

Methodology: Cell survival was assessed by cytofluorometric and clonogenic analysis, estimating apoptosis-associated PARP cleavage by Western blot.

Results: Mutant p53 breast cancer cells were susceptible to PRIMA-1 under normoxia and this response increased under hypoxia. Matched wt p53 breast carcinoma cells were resistant to comparable PRIMA-1 concentrations in normoxia but became sensitive to it under hypoxia. In contrast, hypoxia did not enhance cytotoxicity of nutlin-3a, known to increase wt p53 signaling by inhibit MDM2 binding to p53. Normoxic resistance to PRIMA-1 in wt p53 breast cancer cells was also antagonized by glutathione depletion or Mn-SOD over-expression.

Conclusions: Hypoxia, a common feature of the microenvironment of solid tumors is believed to promote cancer progression and poor clinical outcome. This report is the first to show that hypoxia enhances PRIMA-1 toxicity against human breast cancer cells with mutated or non-mutated TP53 status. We propose that PRIMA-1 may help to counteract hypoxia-acquired resistance to cancer therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C36.
Abstract C70: Antitumor activity of CUDC-907, a single small molecule inhibitor that targets both PI3K and HDAC, in hematologic cancer models.
Authors: Bao Rudi , Wang Dagong , Qu Hui , Wang Jing , Atoyan Ruzanna , Xu Guang-Xin , Yin Ling , Zifcak Brian , Borek Mylissa , Samson Maria , Ma Anna , DellaRocca Steven , Zhai Hai-Xiao , Lai Cheng-Jung , Pepicelli Carmen , Cai Xiong , Qian Changgeng
Published: June 2012

In order to achieve cancer signaling network disruption and overcome primary and/or secondary resistance to standard of care agents in hematologic cancers, we have developed a novel class of dual HDAC and PI3K inhibitors by integrating a HDAC inhibitory functionality into a pharmacophore of PI3K inhibitors. Utilizing structure-based design and extensive SAR approach, CUDC-907 has been selected as a clinical candidate that inhibits not only PI3K directly but also other essential signaling pathways indirectly through epigenetic regulation following HDAC inhibition. Enzymatic assays indicate that CUDC-907 potently inhibits Class I PI3K subtypes as well as Class I and II HDAC subtypes. In anti-proliferation assays, CUDC-907 displays potent inhibition of proliferation of a variety of hematologic cancer cells (mean IC50 = 27nM in 23 cell lines). In mechanism studies, CUDC-907 potently and durably inhibits HDAC and PI3K, as indicated by increase of acetylated histone H3, inhibition of phospho-AKT and phospho-STAT3, decrease of anti-apoptotic molecules (BCL-2, survivin, etc.), and induction of P21, acetylated P53 and cleaved caspase3. CUDC-907 is orally bioavailable in animals, and displays a favorable PK profile in tumor-bearing animals. PD studies in xenograft models exhibit that CUDC-907 dose-dependently inhibits both targets, decreases tumor cell proliferation, and induces apoptosis in hematologic tumor xenografts, correlating well with its drug exposure in tumors. In efficacy studies, CUDC-907 inhibits growth of subcutaneously implanted tumor xenografts of hematologic cancers in a dose-dependent manner. Furthermore, in a Daudi NHL model, CUDC-907 is more efficacious than either a single PI3K or HDAC inhibitor reference compound or a combination of the two single agents at maximally tolerated doses. CUDC-907 also displays a favorable safety profiles. Taken together, CUDC-907 may offer greater therapeutic benefits through broad network disruption in hematologic cancer therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C70.
Abstract C73: Anticancer effects of a novel phosphoinositol 3-kinase inhibitor in human hepatocellular carcinoma.
Authors: Lee Ju-Hee , Lee Hyunseung , Yun Sun-Mi , Seo Ju-Hyeon , Jung Kyung Hee , Li Guang-Yong , Hong Sang-Won , Hong Soon-Sun
Published: June 2012

The phosphatidylinositol 3-kinase (PI3K) is one of the most important regulators of cancer cell growth, survival, motility, and metabolism. As PI3K is activated in a wide variety of human malignancies, it is emerging as an attractive target for cancer treatment. Recently, we have designed and synthesized a new series of imidazo [1,2-a] pyridine derivatives as PI3Ka inhibitors. In this study, we investigated the effect of HS-196 [ethyl 6-(5-(2,4-difluorophenylsulfonamido) pyridin-3-yl) imidazo [1,2-a] pyridine-3-carboxylate] in human hepatocellular carcinoma (HCC) cells. HS-196 inhibited phosphorylation of signaling components downstream from PI3K, such as Akt, mTOR, p70S6K and glycogen synthase kinase 3b (GSK3b) by western blotting and immunofluorescence staining. And HS-196 showed anti-proliferative effects in variety of HCC cells in a dose-dependent manner. Interestingly, HS-196 didn't affect the normal liver cell line (HL-7702), while sorafenib and doxorubicin showed cytotoxicity at the same concentration. Also, HS-196 induced apoptosis by increasing the proportion of sub-G1 apoptotic cells, and caused cell cycle arrest at G0/G1 phase. HS-196 increased the expression of p27 and p21 and decreased that of cyclin D1 associated with cell cycle arrest. The induction of apoptosis by HS-196 was confirmed by DAPI and TUNEL staining, and the increases of the cleaved PARP, caspase-3, caspase-9 were observed. Furthermore, HS-196 decreased the expression of hypoxia-inducible factor-1a(HIF-1a) and vascular endothelial growth factor (VEGF) and inhibited the tube formation and migration of human umbilical vein endothelial cells (HUVECs), which were confirmed by Matrigel plug assay performed in BALB/c nude mouse. Taken together, these results demonstrated that HS-196 exhibited its anticancer activity through disrupting the PI3K/Akt pathway, causing cell cycle arrest and consequently inducing apoptosis, and inhibiting angiogenesis in human HCC cells. We suggest that HS-196 may be a potential new candidate for targeted HCC therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C73.
Abstract C78: A variant of the oncogene RET might be a molecular target in BRAFwt melanoma cells.
Authors: Amato Carol M. , Coffey David , Kounalakis Nicole , Robinson Steven , Su Lih-Jen , Robinson William A.
Published: June 2012

Desmoplastic malignant melanomas (DMM) are clinically, pathologically, and molecularly different from other melanomas. Patients with this subset of melanoma are generally older, with tumors exhibiting deeper levels of invasion, a low incidence of nodal involvement, and tend to track along nerves. Previous studies indicate that DMM tumors have a low prevalence of BRAFV600E mutations making them ineligible for targeted therapies with BRAF inhibitors. The oncogene RET is a tyrosine kinase receptor mainly associated with neuroendocrine cancers and is activated by the ligand glial cell-derived neurotrophic factor (GDNF). Numerous studies suggest that given the neurotrophic features of DMM, a variant of RET (G691S, designated RETp) may be a potential molecular target. We examined human melanoma cell lines for RETp and the BRAFV600E mutation and demonstrated that these molecular changes were usually discordant suggesting that RETp might be an attractive molecular target in BRAFwt cells. Further we hypothesized that in tumors with the RETp genotype, certain TKIs may be more effective in inhibiting cell growth in environments rich with GDNF. We screened various melanoma cell lines with and without the RETp genotype and determined their response to clinically available small molecular weight inhibitors. The cell viability effects were accessed in the presence and/or absence of the RET co-receptor, GFRa1, and ligand, GDNF. We show that in cell lines carrying the RETp genotype, GDNF alone increases cell proliferation, and certain small molecular weight inhibitors may be more effective at inhibiting melanoma cell growth in environments rich in GDNF.

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 C78.
Abstract C84: Inhibition of proteasome deubiquitinating activity as a novel cancer therapy.
Authors: D'Arcy Padraig , Brnjic Slavica , Olofsson Maria H. , Fryknas Marten , Lindsten Kristina , De Cesare Michelandrea , Perego Paola , Sadeghi Behnam , Hassan Moustapha , Larsson Rolf , Linder Stig T.
Published: June 2012

Tumor cells display enhanced sensitivity to disruptions in the ubiquitin-proteasome system making this an attractive target for the development of anti-cancer therapies. Ubiquitin-tagged substrates are degraded by the 26S proteasome; a multisubunit complex comprising a proteolytic 20S core particle (20S CP) capped by 19S regulatory particles (19S RP). The 20S CP has evolved as an important target for anti-cancer drug development, resulting in the approval of bortezomib (Velcade®) for the treatment of multiple myeloma. Here, we describe the characterization of the small molecule b-AP15 as a novel class of proteasome inhibitor that functions by abrogating the deubiquitinating (DUB) activity of the 19S RP. b-AP15 inhibits the activity of two 19S RP-associated DUBs, UCHL5 and USP14. Consistent with DUB inhibition, treatment with b-AP15 caused the accumulation of polyubiquitinated proteins in treated cells with higher molecular weight compared to bortezomib treatment and induced a stronger proteotoxic response. Importantly, apoptosis induction by b-AP15 differed from that of bortezomib by being insensitive to disruptions of the p53 tumor suppressor and insensitive to overexpression of the intrinsic apoptotic suppressor Bcl-2. Finally, we show that treatment with b-AP15 inhibited tumor progression in human and mouse tumor in vivo models of breast, lung, colon, head & neck carcinoma and inhibited organ infiltration in an acute myeloid leukemia (AML) model. Our results suggest that inhibiting the DUB activity of the 19S RP may be a novel target for the treatment of 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 C84.
Abstract C99: Beyond bortezomib: Development of Millennium's next-generation proteasome inhibitors.
Authors: Tsu Christopher A. , Blank Jonathan , Garcia Khristofer , Liu Jane , Bruzzese Frank , Lee Edmund , Kao Yueying , Bannerman Bret , Fitzgerald Michael , Fleming Paul , Ciavarri Jeffrey , Hales Paul , Yu Jie , Yang Yu , Berger Allison , Sintchak Michael , Kupperman Erik , Manfredi Mark , Dick Lawrence
Published: June 2012

Bortezomib (Velcade®) is a proteasome inhibitor that has been approved by the U.S. Food and Drug Administration for the treatment of patients with multiple myeloma or relapsed mantle cell lymphoma. It is currently available in more than 90 countries worldwide. The molecule is an N-capped dipeptidyl boronic acid and its molecular mechanism involves slow-tight binding to the chymotrypsin-like (β5) sites of the 26S proteasome. In the development of Millennium's next generation inhibitors, we have investigated several parameters affecting the drug's activity in biological systems. These include tissue proteasome concentration, blood/plasma partitioning and the kinetics of proteasome inhibition in cultured cells. We find that the abundance of the proteasome (approx. 1–5 μM β5 active site concentration) in cells and tissues together with the slow rate of dissociation of bortezomib from the proteasome (110 min. half-life) led to partitioning of the inhibitor in red blood cells, thereby limiting its distribution to potential sites of therapeutic action. Based on the hypothesis that more rapid dissociation from the proteasome should improve tissue distribution, we have developed an investigational, dipeptidyl boronic acid proteasome inhibitor (MLN9708). MLN9708 displays comparable potency (i.e. similar Ki) to bortezomib for the β5 site of the proteasome but a shorter (18 min.) half-life of dissociation. This affects rapid recovery of proteasome activity in tissue culture cells upon washout of the drug as well as reduced blood/plasma partitioning in mice, supporting the hypothesis that a more rapid equilibrium proteasome inhibitor can improve tissue distribution. MLN9708 is currently in phase 1 clinical trials.

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 C99.
Abstract CN08-02: Androgens, biomarkers, and abiraterone.
Authors: de Bono Johann S.
Published: June 2012

We have recently reported positive Phase III trial results for abiraterone acetate (de Bono, Logothetis et al, NEJM 2011), a drug designed and developed at The Institute of Cancer Research and The Royal Marsden Hospital, now approved for the treatment of CRPC patients in the post-docetaxel setting. We have also described the OS benefit associated with cabazitaxel (de Bono, Oudard et al, The Lancet 2010). These agents have improved the outcome of men with CRPC and enabled us to control this disease for long periods of time. Nevertheless, despite these advances, most patients progress with a rising PSA, suggesting that the biological mechanisms causing treatment resistance are associated with reactivation of androgen receptor (AR) signalling (Attard, Cooper & de Bono 2009). Continued AR signalling is implicated as a common determinant of resistance and has become a key target for prostate cancer drug development. Several molecular mechanisms have been proposed to explain AR reactivation in CRPC including gene amplification or overexpression, selection of gain of function mutations, increased expression of constitutively active AR splice variants and upregulation of cross-talk signal-transduction pathways such as AKT. AR mutations usually occur in the ligand-binding domain and widen the specificity of AR to other steroid hormones like estrogens or progestins, to adrenal steroids and/or to exogenous ligands (e.g. anti-androgens or steroids commonly used to treat CRPC). AR signalling can also occur in the complete absence of ligand due to the expression of truncated AR splice variants that contain an intact N-terminal domain (NTD) and DNA binding domain (DBD), but lack the ligand-binding domain (LBD) (Luo, Hu et al. 2009). AR activating phosphorylations through the Ras/MAPK and PI3K/Akt pathways have been also implicated in the restoration of AR activity (Weber, Bakin et al. 2003; Carver, Chapinski et al. 2011). We are developing further rational therapeutic strategies to reverse these mechanisms of resistance and further improve outcome from this disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr CN08-02.
Abstract PL08-04: New ways to impact glutamine metabolism in cancer.
Authors: Cerione Richard A.
Published: June 2012

Our laboratory has a long-standing interest in understanding the involvement of Rho GTPases in cell growth and migration, which recently led to our discovery of a novel signaling connection between these GTPases and elevated glutamine metabolism in cancer cells. This was based on our identification of a small molecule inhibitor that blocks the transformation of fibroblasts by oncogenic Dbl (for Diffuse B cell lymphoma), a Rho GTPase-activator, as well as inhibits the growth of human breast cancer and B lymphoma cells, and shrinks tumors induced by these cancer cells in mice. The effects of the small molecule inhibitor are specific for transformed/cancer cells, as it does not inhibit the growth of normal fibroblasts or mammary epithelial cells. We identified the target of this inhibitor to be an isoform of the metabolic enzyme glutaminase (GLS1), which catalyzes the hydrolysis of glutamine to glutamate. Transformed/cancer cells show markedly elevated levels of GLS1 activity, due to post-translational modifications (phosphorylation) that are dependent on the activation of Rho GTPases and NFκB, and are blocked by the small molecule inhibitor. Recently, we have shown that an important outcome of the metabolic changes exhibited by cancer cells, that can be prevented by the inhibitor, is the generation of vesicular structures (oncosomes) that contain signaling proteins, metabolic enzymes, RNA transcripts and microRNA. Oncosomes, by transferring these components to recipient cells, are capable of conferring transformed properties on to their acceptor cells and thus have been suggested to play important roles in cancer progression. Collectively, these results shed new light on how glutamine metabolism is elevated during tumorigenesis in order to satisfy the ‘glutamine addiction’ of cancer cells, as well as demonstrate the consequences of such metabolic changes and how they might be interrupted. The hope is that these insights will highlight new strategies for therapeutic intervention.

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 PL08-04.