bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 891: The chemokine receptor CXCR7 transduces its signal through mTOR: the role of everolimus
Authors: Ieranò Caterina , Caraglia Michele , Bernile Francesca , Antignani Elena , Napolitano Maria , Riccio Anna , Portella Luigi , Penfold Mark E. , Scala Stefania
Published: August 2012

Everolimus (RAD001, Afinitor) is an mTOR inhibitor FDA-approved for the treatment of patients with advanced clear cell renal cancer (RCC) after failure of treatment with sunitinib or sorafenib, or both drugs. It targets the mammalian target of rapamycin (mTOR) complex inhibiting a serine/threonine kinase regulating PI3K/AKT signaling pathway. Previous evidences demonstrated that the activation of the chemokine receptor CXCR4 involved the mTOR pathway and that CXCR4 was overexpressed in RCC. Recently, also the deorphanized chemokine receptor CXCR7 was described in RCC and defined as an independent prognostic factor. Nevertheless, little is known about the CXCR4-CXCL12-CXCR7-induced signalling. Aim of the study was to investigate if the CXCL12/CXCR4/CXCR7 complex could transduce the signal through mTOR identifying new therapeutic targets. In human renal cancer cells (RXF393, A498) treatment with CXCL12, the CXCR4 and CXCR7 ligand, induced mTOR pathway, as demonstrated through p70S6K and eukaryotic initiation factor 4E binding protein 1 (4E-BP1) induction; the CXCL12 induction is specifically inhibited by AMD3100, a CXCR4 inhibitor, and CCX733, a CXCR7 inhibitor. The inhibition of the mTOR pathway through RAD001 treatment, inhibited CXCL12-induced pERK1/2 and chemotaxis while AMD3100 and CCX733 were not able to inhibit pERK and migration in RXF393 and A498 cell lines suggesting a role of mTOR downstream of CXCR4 and CXCR7. To analyze the CXCR7 transduction pathway the function of p38 kinase, a CXCR7 target, was evaluated. CXCL12 dramatically induced p38 MAPK in cell lines RXF393 and A498 and the p38MAPK induction was specifically inhibited by CCX733, a CXCR7 inhibitory molecule but, interestingly, p38 MAPK is dramatically induced by AMD3100, a CXCR4 antagonist. To further confirm the p38 role downstream of CXCR7, CXCL12 was unable to induce p38 phosphorylation in RXF393 cells CXCR7 siRNA transduced while inhibited by the specific CXCR7 inhibitor CCX733 in RXF393 cells. The treatment with RAD001 in human renal cancer cells inhibited the p38 induction CXCL12-mediated. This is the first evidence demonstrating that p38 is a CXCR7 target in human renal cancer cells and that AMD3100, a specific CXCR4 antagonist, potentiate the CXCL12 activity on CXCR7. Thus the combined inhibition of the three members CXCR4/CXCR7/mTOR is a valid therapeutic strategy to treat RCC inhibiting two cross talking pathways CXCR4-CXCR7 signaling to mTOR.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 891. doi:1538-7445.AM2012-891
Abstract 893: Anticancer effect and mechanism of prostaglandin E2 receptor EP4 antagonist
Authors: Nonomura Kazuhiko , Miyama Katsuyoshi , Kanazawa Kiyoshi , Okumura Takako , Okumura Yoshiyuki , Oshima Masanobu , Takahashi Satoru , Take Yukinori
Published: August 2012

Molecular studies reveal that over-expression of cyclooxygenase-2 (COX-2) is a prominent feature of premalignant and malignant neoplasms. The increased COX-2-mediated prostaglandin-E2 (PGE2) production has a strong association with various cancers, by promoting cell survival, cell growth, migration, invasion, angiogenesis, and immunotolerance. The use of COX-2 selective inhibitors has shown promise in the prevention and treatment of various cancers, however, the chronic use of COX-2 inhibitors is associated with an increased risk of cardiovascular adverse effects. Therefore, there is an urgent need to further understanding of the downstream mechanisms by which PGE2 promotes tumorigenesis and more effective strategies for the treatment of cancer. There are four PGE2 receptors, i.e., EP1, EP2, EP3, and EP4, involved in the pharmacology of PGE2. Accumulating evidences suggest that EP4 is the responsible receptor for PGE2 / COX-2-mediated tumorigenic signals in cancer cells and cancer microenvironment. On the other hands, signals from other prostaglandin receptors, e.g. IP and EP1, are reported to inhibit cancer proliferation or metastasis. These evidences suggest that selective blockade of EP4 would offer anti-cancer efficacy and safety advantages over COX-2 inhibition as cancer therapy. We have developed novel plural EP4 antagonists, with pA2 values of nanomolar range which are selective against other EP receptors. EP4 antagonists inhibited the PGE2-dependent productions of key molecules for cancer promotion i.e. VEGF, IL-23, and IL-6 in macrophages, dendritic cells, and PBMC, respectively. At the same time EP4 antagonist reversed PGE2 -induced TNFα and IL-12 suppression in human whole blood. As a consequence, EP4 antagonists exhibited anti-cancer activity in lung, GI, and prostate cancer models. These results indicate that selective EP4 antagonists show anti-cancer effect mediated by multifaceted mechanisms, and represent an attractive medicine for anti-cancer therapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 893. doi:1538-7445.AM2012-893
Abstract 900: Caveolin-1 silencing arrests the proliferation of glioblastoma cells by inhibition of STAT3 signalling
Authors: Gasperi-Campani Anna , Pancotti Fabia , Roncuzzi Laura
Published: August 2012

Caveolin-1 is an essential structural constituent of caveolae implicated in mitogenic signalling, oncogenesis, angiogenesis, neurodegenerative diseases and senescence. Its role as a tumor suppressor gene or as a tumor promoter seems to strictly depend on cell type and tumor stage/grade. The high expression of caveolin-1 in some tumors in vivo is associated with increased tumor aggressiveness, metastatic potential and suppression of apoptosis. In the present study we investigated the role of Caveolin-1 in human glioblastoma cells proliferation, in which we found cav-1 expressed at high levels (A172, CRS-A2, LI). Results show that siRNA-mediated down-regulation of Cav-1 caused stable arrest of proliferation in each cell line. A marked reduction of cyclin D1 and of CDK4 expression was evident in the cells transfected with Cav-1 siRNA and consequently of phosphoRb. Furthermore, a significant decrease of the expression of Src and p38α and of their down-stream effector STAT3 was evident. Together, these findings indicate that Cav-1 silencing induces an arrest of tumor cells proliferation in vitro by a new inhibitory pathway in glioblastoma multiforme, the most aggressive of the primary central nervous system tumors, and provide new insights into the molecular mechanisms underlying the pro-survival and tumor-promoting functions of Cav-1. Grants from MIUR (RFO, PRIN), Roberto Pallotti's Legacy for Cancer Research, Cornelia Pallotti's Legacy for Cancer Research, University of Bologna, Italy

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 900. doi:1538-7445.AM2012-900
Abstract 901: Mitotic kinase inhibitors synergize with PI3K and Akt inhibitors in a novel model of anaplastic thyroid carcinomas
Authors: Russo Marika A. , Cristofano Antonio Di
Published: August 2012

Anaplastic thyroid carcinoma (ATC) is the most aggressive form of thyroid cancer, and often derives from pre-existing well-differentiated tumors. Despite a relatively low prevalence, it accounts for a disproportionate number of thyroid cancer-related deaths, due to its resistance to any therapeutic approach. We have generated a mouse model in which the simultaneous selective activation of the PI3K pathway and inactivation of p53 in the thyroid epithelial cells leads to the development of ATCs. These tumors display all the features of their human counterpart, including pleomorphism, epithelial-mesenchymal transition, aneuploidy, local invasion and distant metastases. Expression profiling of the murine ATCs reveals a significant overlap with genes found deregulated in human ATC, including genes involved in mitosis control, such as Aurora kinase A (AURKA), its co-activator TPX2, and Polo like kinase-1 (PLK1). These proteins are crucial driving forces for normal mitotic spindle formation, centrosome maturation and separation, and their overexpression has been demonstrated in a wide range of tumors. MLN8237 (AURKA inhibitor), TAK960 and GSK461364 (PLK1 inhibitors) are a promising new generation of anti-mitotic agents. We show that these molecules inhibit cell proliferation and induce cell death in mouse ATC-derived cell lines and in the human ATC cell lines CAL62 and C643. A dose-dependent decrease in the degree of chromosome alignment and spindle bipolarity during mitosis is observed after the treatments, together with a change in mitotic index indicated by the decrease of the mitotic marker pHisH3. FACS analysis reveals a G2/M phase arrest followed by apoptosis. Furthermore, small molecule inhibitors of PI3K or AKT potently synergize with these anti-mitotic compounds. Taken together these data suggest that AURKA and PLK1 inhibitors are promising therapeutic agents against undifferentiated thyroid carcinoma cells, and that concurrent inhibition of key driver pathways is a viable option to increase efficacy in this otherwise invariably lethal cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 901. doi:1538-7445.AM2012-901
Abstract 905: Mirk/Dyrk1B mediates cell survival and G0/G1 phase of cell cycle via interacting with MAPK/ERK pathway in human cancer cells
Authors: Gao Jingchun
Published: August 2012

Minibrain-related kinase (Mirk) known as the dual specificity tyrosine-phosphorylation-regulated kinase (Dyrk) 1B is a serine/threonine kinase. Our recent studies have also demonstrated that knockdown of Mirk by small interfering RNA (siRNA) resulted in reduction of viable cells and cell apoptosis in both ovarian cancer and non-small cell lung cancer (NSCLC) cell lines. Furthermore, it has been reported that Mirk/Dyrk1B can be negatively regulated by mitogenic-activated protein (MAP) / extracellular signal-regulated kinase (ERK) kinase signaling. In this study, we demonstrated the widely overexpressed Mirk protein in variant cell lines of both human ovarian cancer and NSCLC was correlated with the levels of activated ERK examined by western blot analysis. Interestingly, knockdown of Mirk by siRNA in those ovarian cancer cells (OVCAR3, OVCAR10, OVCAR1063, MDAH2774), and NSCLC cells (H292, H441, H1299, PC9) led to increased cell number and cells from G0/G1 into S phase of cell cycle accompanied by up-regulated activation of ERK and its upstream signals, increased cyclin D1, reduced p27, and no evidence of cleaved PARP which are not consistent with our previous findings in the other cell lines. We hypothesized that the increased activation of ERK after Mirk siRNA treatment may block the anti-proliferative effects of Mirk siRNA in some lines or may counterbalance cell loss through apoptosis in human cancer. To examine this further in both OVCAR3 and H292 cells, the increase in cell proliferation induced by Mirk siRNA could be blocked by the MEK inhibitor U0126 in a dose-dependent manner. MEK inhibition abrogated the activation of ERK and subsequent changes in cell cycle proteins (cyclin D1, p27) induced by Mirk knockdown. Combined Mirk siRNA and U0126 induced cell apoptosis in both OVCAR3 and H292 cells. In summary, Mirk may mediate cell survival and G0/G1 phase of cell cycle via interacting with MAPK/ERK pathway in human cancer cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 905. doi:1538-7445.AM2012-905
Abstract 908: Differential role of JAK1/2-STAT3 pathway in drug response and survival of oncogenic Kras colorectal cancer
Authors: Kalimutho Murugan , Allen Wendy , Dunne Philip , Longley Daniel , Johnston Patrick , Schaeybroeck Sandra Van
Published: August 2012

Mutations in the Kras proto-oncogene are found in 40%-45% of colorectal cancer (CRC) patients and confer resistance to EGFR monoclonal antibody (mAb) therapies. The identification of druggable targets uniquely required by KrasMT CRC tumours has the potential to fill a gap in the therapeutic armamentarium of advanced CRC. We carried out microarray profiling of isogenic Kras wild type (WT) and mutant (MT) in vivo CRC models, KrasMT/WT primary colon tumours, pre-treatment metastatic CRC liver biopsies and drug resistant and sensitive CRC cell lines. We have used systems biology approach incorporating pathway analyses of the microarray data followed by siRNA screening to identify novel targets/pathways which are critical for the survival of KrasMT tumours, both basally and following chemotherapy treatment. We found that JAK1/2-STAT3 signaling was essential for the survival of KrasMT CRC cells. Moreover, suppression of JAK1/2-STAT3 activity using RNAi or small molecule inhibitors resulted in more potent increase in apoptosis in KrasMT CRC cells. In addition, treatment with chemotherapy and MEK1/2 inhibition resulted in significant increases in JAK2 and STAT3 activity and this was associated with strong increase in apoptosis when JAK1/2-STAT3 RNAi or small molecule inhibitors were combined with chemotherapy and MEK1/2 inhibition, especially in KrasMT cells. Moreover, we found that these effects were not drug- or cell line-specific. Collectively, using a systems biology approach, we have identified an essential role of JAK1/2-STAT3 signalling in survival of KrasMT CRC models. These findings support the further clinical investigation of JAK/STAT3 inhibitors in conjunction with chemotherapy or MEK inhibition in KrasMT CRC tumours.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 908. doi:1538-7445.AM2012-908
Abstract 911: Vemurafenib FDG-PET preclinical imaging outcomes across BRAF V600E mutant and resistant tumors
Authors: Baudy Andreas R. , Dogan Taner , Flores Judith E. , Hoeflich Klaus P. , Su Fei , van Bruggen Nicholas , Williams Simon P.
Published: August 2012

The BRAF inhibitor vemurafenib (marketed as zelboraf) has recently been FDA approved for the treatment of metastatic melanoma in patients harboring BRAF V600 mutations. PET imaging will be essential for guiding therapy in terms of gauging initial drug response, monitoring for disease relapse, and evaluating combination treatments in clinical trials. Herein, we assess 18F-FDG uptake across V600E mutant and vemurafenib resistant cells. We find that vemurafenib is equally effective at reducing FDG uptake in cell lines harboring either heterozygous or homozygous V600E BRAF but is ineffective in cells with acquired resistance or BRAF WT cells. Combination treatment with MEK inhibitor GDC-0973 results in a highly significant enhancement of efficacy across all twenty lines tested. We show that FDG uptake is driven by Glut-1, and that the membrane localization of the transporter paralleled with drug efficacy. Interestingly, we find that vemurafenib induced increased FDG uptake in cells harboring RAS mutations, as well as in tumors that have acquired vemurafenib drug resistance. Hexokinase II, CRAF, KSR and p-MEK protein levels in sensitive and drug resistant tumors were all associated with decreased measurements of FDG uptake in vivo. Overall, we have demonstrated that FDG PET imaging should be effective at monitoring the efficacy of vemurafenib in V600E melanoma mutants and that any detected increases in tumor uptake will likely be an indication of drug resistance.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 911. doi:1538-7445.AM2012-911
Abstract 913: Erufosine simultaneously induces apoptosis and autophagy by modulating the mTOR signaling pathway in oral squamous cell carcinoma
Authors: Kapoor Vaishali , Zaharieva Maya M. , Berger Martin R.
Published: August 2012

Erufosine (erucylphospho-N, N, N-trimethylpropylammonium) is an i.v. injectable alkylphosphocholine analog, which is active against various hematological malignancies in vitro. In this study, we reveal activity in oral squamous carcinoma cell lines and down-regulation of the mTOR signaling cascade as novel mechanism underlying the anticancer activity of erufosine. To that purpose, four oral squamous cell carcinoma cell lines (Cal27, FaDu, SCC9 and SCC25) were exposed to erufosine and assessed for modulation of cell proliferation, colony formation, induction of autophagy/apoptosis, cell cycle distribution, and signaling of the mTOR pathway. In addition, combination effects of erufosine with decreased p-mTOR expression or cytotoxic drugs were investigated. Erufosine showed dose-dependent cytotoxicity in all cell lines as observed by MTT and clonogenicity assays. It simultaneously induced both autophagy and apoptosis via conversion of LC3BI to LC3BII, caspase 3/7 activation and PARP cleavage, respectively. In addition, G2 cell cycle arrest was observed along with cyclin D1 down-regulation. Subsequently, we observed that erufosine readily down-regulated in a dose-dependent manner the phosphorylation of components of the mTOR signaling pathway, like p-Akt, p-Raptor, p-mTOR, and its downstream substrates p-p70S6K and p-4EBP1. p-PRAS40 was reduced to undetectable levels at the highest concentrations of erufosine. Moreover, blockage of p-mTOR expression by siRNA, increased tumor cell sensitivity to erufosine and the resulting antiproliferative effect was comparable to the respective combination with cisplatin but superior to that with rapamycin. Further, erufosine showed additive tumor cell cytotoxicity in combination with 5-flourouracil and cisplatin. In conclusion, these data indicate that erufosine induces apoptosis, autophagy, cell cycle arrest and down-regulates mTOR signaling in oral cancer cell lines. Thus, it has potential as an anti-oral cancer drug either alone or in combination with other chemotherapeutic agents.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 913. doi:1538-7445.AM2012-913
Abstract 922: ABTL0812: A new drug class with oral antitumor action inhibiting mTOR activity and DHFR expression
Authors: Alfon Jose , Espadaler Jordi , García-Martínez Jose A. , Lizcano Jose Miguel , Domènech Carles
Published: August 2012

ABTL0812* is a lipid analogue that has shown high efficacy by the oral route in mouse models of cancer. Here we show that two clinically validated targets are responsible for the cytotoxic effect of ABTL0812: mTOR (mammalian target of rapamycin), as shown by the dramatic reduction in S6 phosphorylation, and dihydrofolate reductase (DHFR), as shown by its reduced expression, resulting in autophagic cell death. Moreover, the compound's cellular potency increases with incubation time, and it has a long lasting cytotoxic effect after removing the compound from the incubation medium. In vivo efficacy was determined in a human lung cancer xenograft model by subcutaneously injecting A549 human lung adenococarcinoma cells into nu/nu mice. ABT0812 was administered daily at two dose levels and its impact on tumor volume was measured. ABT0812 showed a similar efficacy to docetaxel but with much lower toxicity, and better efficacy than erlotinib. Histological analysis of the tumors revealed increased necrotic area, more inflammatory cells and fewer cells undergoing mitosis. Additionally, plasma levels of ABTL0812 were inversely correlated with tumor volume, reinforcing the concentration-effect relationship. A parallel study was performed to evaluate ABTL0812 efficacy in a pancreatic cancer model. Nu/nu mice were subcutaneously injected with MiaPaCa-2 cells and the volume of xenograft was used as a measurement of efficacy. Again, ABTL0812 showed a statistically significant reduction of tumor volume, increased tumor cell death, and better tolerance than gemcitabine in the mice. DMPK properties in rats and dogs showed very low in vitro hepatic metabolism, ∼50% bioavailability and half lives that calculate to single daily oral administration. Safety pharmacology studies with very high doses of the compound showed no impact on the central nervous system. Ongoing toxicological studies show that the margin between efficacy and toxicity is broad. In conclusion, ABTL0812 is a lipid analogue that hits two clinically validated targets: mTOR and DHFR. This multitarget property increases antitumor efficacy and reduces drug resistance. In addition, preliminary in vivo results indicate that the potential therapeutic margin will be high. * Protected by PCT WO 2010/106211, by Escribá Ruiz PV, et al., licensed to AB-Therapeutics, SL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 922. doi:1538-7445.AM2012-922
Abstract 927: The ligand-gated Cl- channel GABA inhibits colon cancer invasion following activation by pharmacological treatments
Authors: Ceniccola Kristin E. , House Carrie D. , Bateman Ryan J. , Nguyen Amy , Obias Vincent , Ceryak Susan M. , Mendelowitz David , Lee Norman H.
Published: August 2012

Gamma-aminobutyric acid (GABA) receptors are ligand-gated ion channels that are essential for neurotransmitter function and neuronal cell homeostasis. Activation of these channels triggers the opening of a chloride-sensitive pore, which causes a hyperpolarization via an influx of chloride ions into the cell. The presence of these channels was recently implicated in several cancers, and the neurotransmitter GABA has been cited as a tumor suppressor. We propose that commercially available pharmacological treatments that manipulate GABA receptor function could be repurposed to target cancer. We have identified functional GABA receptors in a spectrum of colon cancer cell lines and examined the effects of the channels on invasion of the metastatic cell line SW620. Electrophysiological techniques were used to confirm that these channels have functional expression. Treatment with propofol, an agonist which slows the channel closing time, and GABA led to a decrease in invasive potential. Conversely, treatment with the antagonist gabazine, which allosterically blocks GABA from binding in the channel, facilitated invasion by preventing chloride influx. Curiously, treating the cells with bicuculline, which blocks GABA's inhibitory action, led to a decrease in invasion. In some situations bicuculline can also act as a GABA agonist by causing spontaneous gating of homomeric β3 channels. The expression of the β3 subunit was also confirmed through immunocytochemistry. In addition to colon cancer cell lines, β3 expression was detected at higher quantities in colon cancer patient samples compared to matched controls. To further understand how GABA signaling is implicated in cancer, we have looked at the association of GABA with the EGF signaling pathway, which is commonly dysregulated in cancer. The EGF pathway has also been linked with a loss of the glucagon receptor in liver cancer, suggesting that a common pathway may exist between GABA and glutamate that can be exploited for treatment. Altogether, our data suggest that ligand-gated GABA channels inhibit the metastatic potential of cancer cells and can be targeted to treat colon cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 927. doi:1538-7445.AM2012-927
Abstract 930: p38 MAPK is required for the antitumor activity of the vascular disrupting agent DMXAA
Authors: Lou Liguang , Wu Qiong , Quan Haitian , Xu Yongping
Published: August 2012

5, 6-Dimethylxanthenone-4-acetic acid (DMXAA), a potent vascular disrupting agent, selectively destroys established tumor vasculature, causing a rapid collapse in blood flow that ultimately leads to inhibition of tumor growth. In this study, we explored the role of p38 MAPK in the antitumor activity of DMXAA. It was found that p38 MAPK was critically involved in DMXAA-induced cytoskeleton reorganization in endothelial cells and TNF-α production in macrophages, both of which were essential for DMXAA-induced vascular disruption. Inhibition of p38 MAPK significantly attenuated DMXAA-induced actin cytoskeleton reorganization in human umbilical vein endothelial cells and TNF-α production in macrophages. In vivo, p38 MAPK inhibition attenuated the immediate reduction in tumor blood flow induced by DMXAA treatment (<30 min) by inhibiting actin cytoskeleton reorganization in tumor vascular endothelial cells, and blunted the long-lasting (>4 h) DMXAA-induced shutdown of the tumor vasculature by inhibiting intratumoral TNF-α production. Our results indicate that p38 MAPK is required for DMXAA-induced endothelial cell cytoskeleton reorganization and TNF-α production, and thus regulates DMXAA-induced antitumor activity.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 930. doi:1538-7445.AM2012-930
Abstract 931: The combination of the dual mTORC1/mTORC2 inhibitor AZD2014 and paclitaxel in human ovarian cancer models
Authors: Stewart Adam , Thavasu Parames , Heaton Simon , Banerjee Susana , Kaye Stan B. , Banerji Udai
Published: August 2012

Background Weekly administration of paclitaxel is increasingly used to treat patients with platinum-resistant ovarian cancer. We have previously reported that activation of the phosphatidylinositide-3-kinase pathway as measured by p-p70S6K is associated with resistance to chemotherapy in studies using ovarian cancer cells isolated from ascites (Carden et al, 101st AACR Annual Meeting, 2010; Abstract no. 788). We thus set out to explore the combination of paclitaxel and an inhibitor of the mTORC1/2 complex, AZD2014, in ovarian cancer cell line models. Purpose We aimed to study the effects of combining paclitaxel and the mTORC1/2 inhibitor AZD2014 on growth inhibition in a panel of human ovarian cancer cell lines. We also studied the effects of drug administration schedule on growth inhibition. Methods A panel of 5 human ovarian cell lines was studied: A2780, CH1, SKOV3, IGROV and OVCAR-3. The effects of paclitaxel and AZD2014 administered concomitantly on cell growth were studied using 96hr sulforhodamine B assays. Combination indices (CI) were calculated using median effect analysis and a one-sided t-test was performed to calculate significant differences from a hypothetical value of 1 (indicating additivity). All experiments were carried out in triplicate. Results The combination was additive when drugs were administered concomitantly. In addition, in A2780 and SKOV3 cell lines exposed to paclitaxel followed by AZD2014 the combination indices were 1.112 and 1.099 respectively. Conclusion AZD2014, a novel mTORC1/2 inhibitor, and paclitaxel have additive growth inhibitory effects in a panel of ovarian cancer cell lines when administered concomitantly. Further experiments to understand the effects of this combination on apoptosis and signal transduction are ongoing. The combination of AZD2014 and paclitaxel has potential applications in the treatment of ovarian cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 931. doi:1538-7445.AM2012-931
Abstract 935: Lapatinib and other tyrosine kinase inhibitors greatly potentiate doxorubicin-induced damage to cardiac myocytes
Authors: Hasinoff Brian B. , Patel Daywin , Wu Xing
Published: August 2012

Lapatinib (Tykerb) is dual tyrosine kinase inhibitor targeting the HER2 (ERBB2) and EGFR (ERBB1, HER1) pathways. Lapatinib has been shown in a clinical trial to produce low levels of cardiotoxicity that is reversible. Using a neonatal rat cardiac myocyte model we have investigated the ability of lapatinib alone, and in combination with doxorubicin, to damage myocytes. Lapatinib alone at pharmacological concentrations only slightly induced myocyte damage. However, doxorubicin-induced myocyte damage was greatly potentiated by the addition of low nanomolar lapatinib concentrations. Because trastuzumab also targets ERBB2 receptors, the lapatinib/doxorubicin combination also provides a good model to probe the mechanism of the increased cardiotoxicity caused by the concurrent use of trastuzumab and doxorubicin. Lapatinib treatment alone had little or no effect on myocyte mitochondrial membrane potential, on oxidation of intracellular DCF (dichlorofluorescein), on intracellular ATP levels, or on caspase 3/7 induction. While the doxorubicin cardioprotective agent dexrazoxane was able to greatly reduce doxorubicin-induced myocyte damage, it could only partially reduce the increase in myocyte damage produced by the lapatinib/doxorubicin treatment. Lapatinib alone had little effect on the phosphorylation status of ACC (acetyl-coenzyme A carboxylase) and AKT. Lapatinib alone decreased phosphorylated ERK (MAPK), which may have, in part, contributed to the increased doxorubicin-mediated myocyte damage. As measured by flow cytometry lapatinib-treated myocytes demonstrated an increased accumulation of doxorubicin. As lapatinib is a strong inhibitor of several ATP-dependent ABC-type efflux transporters, this likely occurred because lapatinib blocked doxorubicin efflux, thereby increasing intracellular doxorubicin concentrations. These results suggest that the clinical use of concurrent doxorubicin and lapatinib should be approached with care due to the possibility of lapatinib increasing doxorubicin cardiotoxicity. Several other kinase inhibitors (imatinib, dasatinib, sorafenib, sunitinib, gefitinib, pazopanib, nilotinib, erlotinib, vandetanib and canertinib) were also examined for their ability to potentiate doxorubicin-induced myocyte damage and induce an increase in intracellular doxorubicin levels. Support: CIHR and a Canada Research Chair in Drug Development to BBH.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 935. doi:1538-7445.AM2012-935
Abstract 959: ERα1 represses breast cancer EMT by inhibiting EGFR-mediated downregulation of E-cadherin
Authors: Thomas Christoforos , Rajapaksa Gayani , Nikolos Fotis , Hao Ruixin , Katchy Anne , Bondesson Maria , Krishnamurty Savitri , Esteva Francisco , Gustafsson Jan-Ake
Published: August 2012

Although epithelial to mesenchymal transition (EMT) is associated with specific breast cancer phenotypes, such as the basal-like and claudin-low tumors, there is a lack of validated markers, which can distinguish tumors with poor clinical outcome and high metastatic potential. Estrogen receptor beta (ERα) has been shown to regulate invasion in prostate cancer. However, it is still unclear if ERα by influencing invasion can predict metastasis in breast cancer. Here we show that wild-type ERα (ERα1) inhibits EMT and invasion in basal-like breast cancer cells when they grow either in vitro or in vivo in zebrafish. This correlates with an ERα1-mediated upregulation of miR-200a, miR-200b and miR-429 and the subsequent repression ZEB1 and SIP1, which results in increased expression of E-cadherin. Downregulation of the basal marker EGFR was found to be involved in the ERα1-mediated mesenchymal to epithelial transition since induction of EGFR expression or treatment with EGF abolished the ability of ERα1 to sustain the epithelial phenotype. This inverse correlation of ERα1 with EGFR and its positive association with epithelial markers was additionally observed in breast cancer specimens. These results strengthen the association of ERα1 with the regulation of EMT and propose the receptor as potential crucial marker in predicting survival and metastasis in breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 959. doi:1538-7445.AM2012-959
Abstract 96: From genome-wide association studies (GWAS) to functional genomics of prostate cancer: exploring the role of candidate transcripts through RNAi-based analysis
Authors: Tang Wei , Jones Tamara L. , Pitt Jason , Ambs Stefan , Caplen Natasha J. , Prokunina Ludmila
Published: August 2012

Recent genome-wide association studies (GWAS) have identified multiple genomic regions that harbor single nucleotide polymorphisms (SNPs) associated with human prostate cancer. Determining the biological basis of association data requires the identification of molecular phenotypes that correlate to these sequence variants. However, many of these variants are located in intergenic regions or gene deserts, making it difficult to identify the underlying biological mechanisms these association studies suggest. Two SNPS identified by prostate cancer GWAS include rs10486567 located within intron 2 of JAZF1 gene on chromosome 7p15.2, and rs4430796 located on chromosome 17 near the HNF1B gene. JAZF1 (JAZF zinc finger 1) is a putative transcriptional repressor. SNPs in JAZF1 have also been associated with height body stature, and risk of type-2 diabetes and systemic lupus erythematosus. HNF1B (HNF1 homeobox B) is a homeodomain containing transcription factor; SNPs at this locus show an inverse association with risk of type-2 diabetes and this locus has also been identified as associated with endometrial cancer susceptibility. As the function of JAZF1 and HFNB1 is poorly characterized we are using RNAi based loss-of-function analysis, initially in a prostate cancer cell line, to assess the molecular consequences of silencing these genes. First the transfection conditions for the prostate cancer cell line LNCAP were optimized for synthetic siRNA transfection and multiple siRNAs (from two different vendors) corresponding to JAZF1 and HFN1B were assessed for efficiency of gene specific silencing. To assess the functional consequence of silencing in an unbiased manner we have generated gene specific expression profiles for JAZF1 and HFN1B in LNCAP cells. Briefly, gene expression microarray analysis was conducted on RNA prepared 72 hours post siRNA transfection and expression profiles were generated from data using three different siRNAs corresponding to each gene transfected in triplicate compared to negative control transfected cells. Following silencing of JAZF1 approximately 150 genes were identified as showing significant changes in gene expression, with over 500 other genes showing evidence of altered expression but not at significant level. Following silencing of HFN1B, over 250 genes were identified as showing significant changes in gene expression, with over 400 other genes showing evidence of altered expression but not at significant level. Further analysis and validation of these expression profiles is ongoing.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 96. doi:1538-7445.AM2012-96
Abstract 970: Multi-layer and integrative analysis of the whole transcriptome in Asian gastric cancer: AMPKβ modulation in cancer progression
Authors: Kim Yon Hui , Liang Han , Liu Xiuping , Izzo Julie , Lemos Robert , Lee Ju-Seog , Cho Jae Yong , Cheong Jae Ho , Kim Hoguen , Li Min , Downey Thomas J. , Dyer Matthew D. , Sun Yongming , Sun Jingtao , Beasley Ellen M. , Chung Hyun Cheol , Noh Sung Hoon , Weinstein John N. , Liu Chang-gong , Powis Garth
Published: August 2012

We performed whole-transcriptome profiling of gastric cancer_the most common cancer in developing countries and the second leading cause of cancer deaths in the world. Applying a innovative SOLiD RNA-Seq approach to 24 gastric tumor samples and 6 noncancerous samples, we generated 3.0 billion short reads to quantitatively measure the abundance of mRNAs and small non-coding RNAs. We then developed a multi-layer analysis to identify differentially expressed mRNAs and microRNAs, and novel single-nucleotide mutations candidates associated with gastric cancer. With the insights from the multi-layer analysis, we experimentally demonstrated a critical role for AMPKβ modulation in gastric cancer progression. This work provides a multi-faceted portrait of the Asian gastric cancer transcriptome, which facilitates the elucidation of molecular mechanisms of gastric carcinogenesis and the development of targeted therapies. By integrating data obtained on the expression of both mRNa and miRNa molecules, we were able to identify certain gene signatures uniquely expressed in gastric cancer. This gene signatures along with gastric cancer-related therapeutic target gene signature, showed molecular changes as robust biological markers. Integration of differentially expressed mRNAs and microRNA profiles allowed us to identify potential miRNA drivers of disease progression. We demonstrated the translational relevance of AMPKβ as a potential therapeutic target for treatment and for prediction of early stage gastric cancer. This work lays a critical foundation for the identification of molecular mechanisms of gastric carcinogenesis and the development of related targeted therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 970. doi:1538-7445.AM2012-970
Abstract 972: Direct activation of pro-apoptotic BAX as a novel strategy for cancer therapy
Authors: Gavathiotis Evripidis , LaBelle James L. , Reyna Denis , Bellairs Joseph , Walensky Loren D.
Published: August 2012

BCL-2 family proteins are essential regulators of cellular life and death and, when deregulated, contribute to the development, maintenance, and chemoresistance of human cancer. Anti-apoptotic members contribute to cancer pathogenesis by sequestering the α-helical BH3 death domains of their pro-apoptotic counterparts such as BAX. The anti-apoptotic groove that binds and neutralizes BH3 helices has been successfully targeted by small molecules and stapled peptides in an effort to “inhibit the inhibitors” of apoptosis. Using a Stabilized Alpha-Helix of BCL-2 domain (SAHB) modeled after the BIM BH3 helix, we previously identified a geographically distinct BH3-binding groove that mediates the direct activation of BAX, suggesting a new strategy for inducing apoptosis by flipping BAX's “on switch”. Engagement of the novel site by BIM SAHB directly activates BAX (Gavathiotis et al. Nature, 2008), unleashing a succession of key conformational changes that culminates in the formation of toxic mitochondrial pores (Gavathiotis et al. Mol Cell, 2010). Here, we demonstrate that BIM SAHB effectively overcomes the apoptotic blockades of a series of diverse hematologic cancer cells by broadly targeting inhibitory anti-apoptotic complexes and directly activating BAX. Importantly, BIM SAHB induces dose-responsive caspase 3/7 activation and the morphologic features of apoptosis. To identify a BAX-selective agent, we further performed a computational screen to identify BAX activator molecules (BAMs) capable of directly engaging the BAX trigger site. We demonstrate by competitive fluorescence polarization binding assays and NMR analyses that BAM7 engages the BAX trigger site and, as a result, promotes the functional oligomerization of BAX. Strikingly, the molecule does not interact with the canonical BH3 binding pocket of anti-apoptotic proteins and induces cell death in a BAX-selective fashion. These first stapled peptide and small molecule gain-of-function modulators of a BCL-2 family protein highlight a new pharmacologic paradigm for induction of cancer cell apoptosis through direct activation of BAX.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 972. doi:1538-7445.AM2012-972
Abstract 977: Elevated MDM2 protein contributes to activity of MDM2 antagonists by enabling p53 induction of antitumor microRNAs
Authors: Xia Mingxuan , Huang Baoying , Chu Wei , Vassilev Lyubomir T.
Published: August 2012

Small-molecule inhibitors of p53-MDM2 binding, the nutlins, can free p53 from MDM2 control and effectively activate its growth suppressive and pro-apoptotic activity in cancer cells (Vassilev et al., Science, 2004, 303, 844). Optimized members of this family of molecules are currently under clinical investigation as novel therapeutic modality for cancers expressing wild-type p53. We have shown previously that MDM2 antagonists are most effective in cancer cells that overproduce MDM2 as a result of mdm2 gene amplification (Tovar et al., PNAS, 2006, 103, 1888). Here, we show that reduction of MDM2 protein by RNA interference decreases the effectiveness of nutlin-3a in osteosarcoma cells with mdm2 gene amplification, suggesting that MDM2 protein contributes to antitumor activity of MDM2 antagonists. In search of the mechanism behind this phenomenon, we found that nutlin-induced p53 activates the transcription of a specific subset of microRNAs in cancer cells with mdm2 amplification but not in cells expressing normal levels of MDM2 protein. Five specific members of the class (miR1, miR133, miR141, miR184, miR375) were studied and showed that their p53-dependent transcription is also dependent on the presence of high levels of MDM2 protein, generated by continuous p53 activation of MDM2 in the presence of nutlin. Weak p53 response elements were found in the promoter regions of all five miRs and p53 binding was conformed by ChIP analysis of cell lysates and p53 reporters in experiments with miR375. Transcriptional cofactor p300 was found elevated in cancer cells with mdm2 gene amplification and dependent on the presence of high MDM2 protein levels. Our experimental data suggests that in the presence of high p300, and high MDM2, generated by nutlin treatment, p53 acquires the ability to activate weak p53-responsive miR promoters in MDM2-amplified cells. Interestingly, miR mimics of two of the five p53-induced miRs showed growth suppressive effects in cancer cells and enhanced the activity of low dose nutlin-3a. These findings reveal a novel mechanism for modulation of p53 transcriptional activity and indicate that the high levels of MDM2, generated in mdm2-amplified cancer cells in the presence of nutlin, contribute to its antitumor.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 977. doi:1538-7445.AM2012-977
Abstract 987: Overexpression of 14-3-3α in cancer cells activates PI3K via binding the p85 regulatory subunit
Authors: Xu Jia , Neal Christopher L. , Li Ping , Mori Seiji , Yang Jun , Neal Nina N. , Zhou Xiaoyan , Wyszomierski Shannon L. , Yu Dihua
Published: August 2012

The ubiquitously expressed 14-3-3 proteins regulate many pathways involved in transformation. Previously, we found that 14-3-3α overexpression increased Akt phosphorylation in human mammary epithelial cells. Here, we investigated the clinical relevance and molecular mechanism of 14-3-3α overexpression-mediated Akt phosphorylation and the potential impact on breast cancer progression. We found that 14-3-3α overexpression was significantly (P = 0.005) associated with increased Akt phosphorylation in human breast tumors. Additionally, 14-3-3α overexpression combined with strong Akt phosphorylation was significantly (P=0.01) associated with increased cancer recurrence in patients. In contrast, knockdown of 14-3-3α expression by siRNA in cancer cell lines and tumor xenografts reduced Akt phosphorylation. Furthermore, 14-3-3α enhanced Akt phosphorylation through activation of PI3K. Mechanistically, 14-3-3α bound to the p85 regulatory subunit of PI3K and increased PI3K translocation to the cell membrane. A single 14-3-3 binding motif encompassing serine 83 on p85 is largely responsible for 14-3-3α-mediated p85 binding and PI3K/Akt activation. Mutation of serine 83 to alanine on p85 inhibited 14-3-3α binding to the p85 subunit of PI3K, reduced PI3K membrane localization and activation, impeded anchorage independent growth and enhanced stress induced apoptosis. These findings revealed a novel mechanism by which 14-3-3α overexpression activates PI3K, a key node in the mitogenic signaling network known to promote malignancies in many cell types.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 987. doi:1538-7445.AM2012-987