bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 859: CDK11 (PITSLRE) kinase expression is critical for human cancer cell growth and proliferation
Authors: Duan Zhenfeng , Choy Edwin , Harmon David , Mankin Henry , Hornicek Francis
Published: August 2012

In the search to identify kinases required for human cancer cell growth, we found CDK11 (PITSLRE) by a comprehensive human kinome-wide shRNA screen to be critical for human cancer cell growth and proliferation. We observed that the expression level of CDK11 was elevated in a variety of human cancer cells and tumor tissues. Furthermore, knock-down of CDK11 either by lentiviral shRNA or by synthetic siRNA inhibits cell growth and induces apoptosis in human cancer cells. In these cells, suppression of CDK11 reduces the expression of several antiapoptotic genes essential for tumor cell survival and proliferation including MCL-1, BcL-XL and survivin. We showed by immunohistochemical analysis that osteosarcoma and ovarian cancer patients with high CDK11 tumor expression levels were associated with significantly shorter survival than patients with lower expression levels of CDK11 expression. Systemic administration of In Vivo Ready siRNA of CDK11 reduced tumor growth in an osteosarcoma s.c. xenograft model. Taken together, these observations suggest that CDK11 signaling is essential in human cancer cell growth and survival. CDK11 may serve as a promising therapeutic target in the treatment of human 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 859. doi:1538-7445.AM2012-859
Abstract 864: Novel synthetic berbamine derivatives inhibit Jak2/Stat3 signaling and induce apoptosis of human melanoma cells
Authors: Nam Sangkil , Xie Jun , Perkins Angela , Ma Yuelong , Yang Fan , Wu Jun , Wang Yan , Xu Rong-zhen , Huang Wendong , Horne David A. , Jove Richard
Published: August 2012

Persistent Jak/Stat3 signal transduction plays a crucial role in tumorigenesis and immune development. Activated Jak/Stat3 signaling has been validated as a promising molecular target for cancer therapeutics discovery and development. Berbamine (BBM), a natural bis-benzylisoquinoline alkaloid, was identified from the traditional Chinese herbal medicine Berberis amurensis used for treatment of cancer patients. While BBM has been shown to have potent antitumor activities with low toxicity in various cancer types, the molecular mechanism of action of BBM remains largely unknown. Here, we determine the antitumor activities of thirteen synthetic berbamine derivatives (BBMDs) against human solid tumor cells. BBMD3, which is the most potent in this series of novel BBMDs, exhibits over 6-fold increase in biological activity compared to natural BBM. Moreover, BBMD3, directly inhibits Jak2 autophosphorylation kinase activity in vitro with IC50 = 0.69 μM. Autophosphorylation of Jak2 kinase at Tyr1007/1008 sites also was strongly inhibited in the range of 1 μM to 5 μM of BBMD3 in human melanoma cells 4 h after treatment. Following inhibition of autophosphorylation of Jak2, BBMD3 blocked constitutive activation of downstream Stat3 signaling in melanoma cells. BBMD3 also down-regulated expression of Stat3 target proteins Mcl-1and Bcl-xL, associated with induction of apoptosis. In sum, our findings demonstrate that the novel berbamine derivative BBMD3 is an inhibitor of the Jak2/Stat3 signaling pathway, suggesting evidence for a molecular mechanism whereby BBMD3 exerts at least part of apoptosis of human melanoma cells. In addition, BBMD3 represents a promising lead compound for development of new therapeutics for cancer treatment.

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 864. doi:1538-7445.AM2012-864
Abstract 873: Combined targeting of Akt and MEK with the Akt inhibitor GDC-0068 and MEK inhibitor GDC-0973 demonstrates synergistic anti-tumor effects
Authors: Nannini Michelle A. , Hong Rebecca , Lee Brian B. , Arrazate Alfonso , Kassees Robert , Lin Jie , Degtyarev Michael , Sampath Deepak , Lin Kui
Published: August 2012

Background: Akt, a serine/threonine protein kinase, and MEK, a dual specificity kinase, are key signaling nodes in the PI3K/Akt/mTOR and the Ras/Raf/MAPK pathway, respectively. Both Akt and MEK play key roles in regulating numerous cellular processes such as cell proliferation, growth, survival, protein synthesis and oncogenic transformation. Many cancer types have alterations in both of these pathways and inhibiting only one of these pathways can result in up-regulation of the other pathway. We previously reported on a potent highly selective ATP-competitive pan-Akt inhibitor, GDC-0068 as well as a potent selective inhibitor of MEK, GDC-0973 that are currently in Phase 1 clinical trials. We hypothesized that dual inhibition of both MEK and Akt pathways with the combination of these two agents would induce synergistic antitumor activity. Methods: In these studies, we evaluated the efficacy of GDC-0068 and GDC-0973 both individually and in combination on a panel of cancer cell lines. Cells were treated with either GDC-0068 or GDC-0973 or in combination at increasing concentrations and assayed after 4 days for viability. For in vivo studies, tumor cells were subcutaneously implanted in the flank of female NCR.nude mice. Once tumors reached sufficient size, mice were dosed orally for 21 days with GDC-0068, GDC-0973 or the combination of both compounds. Results: In vitro, the combination of GDC-0068 and GDC-0973 results in enhanced inhibition of cell viability compared to either single agent alone. Synergistic effects are observed in multiple cell lines; especially in cell lines that have activation of the Ras/Raf/MAPK pathway or both pathways (e.g. via the combination of PTEN loss or PI3K mutations and Ras or BRaf mutations). Combined knockdown of downstream targets of both Akt and MEK is observed at concentrations where a synergistic effect is observed, with enhanced knockdown of several converged targets. Increased cell death is also observed. These results were recapitulated in vivo in xenograft models, where the combination of GDC-0068 and GDC-0973 resulted in increased tumor growth inhibition or regression compared to either single agent alone. All combinations tested were well tolerated as assessed by animal body weights and mortalities. Conclusions: Our studies demonstrate significant combination benefit between GDC-0068 and GDC-0973 on cell viability in vitro and tumor growth in vivo. These data support the clinical development of the combination of these two compounds.

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 873. doi:1538-7445.AM2012-873
Abstract 90: An evaluation of the genes involved in the Base Excision Repair (BER) pathway as potential phenotypic modifiers of breast cancer risk in BRCA1 and BRCA2 mutation carriers.
Authors: Vaclová Tereza , Milne Roger L , Saucedo-Cuevas Laura P , Radice Paolo , Blanco Ignacio , de la Hoya Miguel , Durán Mercedes , Díez Orland , Cajal Teresa Ramón y , Martínez-Bouzas Cristina , Fostira Florentia , Godino Javier , Benitez Javier , Osorio Ana
Published: August 2012

Germ-line mutations in the BRCA1 and BRCA2 genes confer a high lifetime risk of developing breast and other cancers. However, remarkable differences exist regarding disease manifestation in mutation carriers, suggesting the existence of other genetic modifier factors. Given that both BRCA1 and BRCA2 are involved in the repair of double-strand breaks (DSBs) mainly by Homologous Recombination, SNPs in genes involved in DNA repair are good candidates to be tested as phenotypic modifiers. The Base Excision Repair (BER) pathway could be particularly interesting given the relation of synthetic lethality that exists between one of the components of this pathway, PARP1, and both BRCA1 and BRCA2. To test our hypothesis we have performed a comprehensive analysis of the 18 genes involved in BER, in a series of 2000 BRCA1 and BRCA2 mutation carriers from the Spanish Consortium for the Study of Hereditary Breast Cancer, the Istituto Nazionale Tumori and the National Centre for Scientific Research “Demokritos”. For this purpose we have used a tagging SNP approach in which we have evaluated the common genetic variation in the 18 genes using the VeraCode GoldenGate 144 SNP Genotyping Kit. Preliminary results have showed statistically significant associations with cancer risk in BRCA1 and/or BRCA2 mutation carriers for 46 SNPs (p<0.05), seven of them showing associations with p<10−3. Genetic and functional analyses are currently on-going to validate the most statistically significant effects.

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 90. doi:1538-7445.AM2012-90
Abstract 904: The TNIK kinase is a potential target in non-small cell lung and gastric cancer
Authors: Yu Derek Dehua , Zhang Xiuhua , Wang Christina , Hu Eva , Dong Harvey , Zhu Mike , Qian Ziliang , Gao Zeren , Gao Zeren , Fan Joan , Su Xinying , Xu Jessie , Zheng Li , Yin Lucy , Ji Qunsheng
Published: August 2012

Traf2- and Nck-interacting kinase (TNIK) is one of germinal centre kinase (GCK) family members involved in cytoskeleton organization and neuronal dendrite extension. Emerging evidence indicated that TNIK is essential in activation of WNT pathway and colon cancer growth. To search for novel genetic aberrations that drive carcinogenesis, we performed microarray-based comparative hybridization (aGCH) to screen gene copy number variations in primary tumor samples and found TNIK gene is amplified in 19.2 % (29/151) of Chinese non-small cell lung cancer and 7 % (8/106) of Chinese gastric cancer patients. Interestingly, the amplification in NSCLC is highly enriched in squamous NSCLC patients (41.1%, 28/68). Theses amplifications were confirmed by fluorescence in situ hybridization (FISH) analysis. To further understand the function of TNIK gene amplification, PAMC82 human gastric cancer and T47D colon cancer cell lines with TNIK amplification were identified. RNA-interference-mediated silencing of TNIK resulted in significantly reduced cell growth and increased cell death in the TNIK amplified, but not in the non-amplified, tested cell lines. Together, our results suggest that TNIK is a novel therapeutic target in NSCLC and gastric cancer and TNIK amplification can be potentially used for patient selection.

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 904. doi:1538-7445.AM2012-904
Abstract 910: Selective inhibition of Rac1 and Cdc42 in ovarian cancer using the R-enantiomer of ketorolac
Authors: Kenney Shelby R. , Oprea Tudor , Ursu Oleg , Sklar Larry , Lomo Lesley , Muller Carolyn , Gao Yuna , Wandinger-Ness Angela , Hudson Laurie
Published: August 2012

Ovarian cancer is the 5th leading cause of cancer death for women in the United States and is frequently diagnosed at late stage with multiple secondary metastases. Ras-homologous (Rho) family GTPases contribute to metastatic dissemination through regulation of actin reorganization, cell motility, cell-cell and cell-extracellular matrix adhesion. Rho GTPases are altered in a number of human cancers and our work provides the first evidence for dysregulation of Rac1 and Cdc42 in ovarian cancer. These findings suggest that Rac1 and Cdc42 inhibitors represent potential therapeutics for ovarian cancer. Using high throughput screening we identified the R-enantiomers of ketorolac and naproxen as novel inhibitors of Rac1 and Cdc42. Although it has been noted that R-enantiomers of nonsteroidal anti-inflammatory drugs are poor inhibitors of cyclooxygenase (COX) activity, little is known about the pharmacologic activities or targets of the R-enantiomers. The objective of this study was to investigate the effects of R-ketorolac on ovarian cancer. The effects of racemic, R- and S-ketorolac were investigated using SKOV3ip ovarian cancer cells. The compounds NSC23766 and MLS0000693334 were used as positive controls for Rac1 and Cdc42 respectively. An in vitro G-LISA assay indicated R-ketorolac, and not S-ketorolac, inhibits Rac1 and Cdc42 activity. In cells, R-Ketorolac, not S-ketorolac, inhibits cell:cell adhesion and cell migration. An intra-peritoneal xenograft model of tumor implantation was used to determine the effects of drugs in vivo. Racemic ketorolac decreased the number of implanted tumors by 70%. To elucidate the mechanism of GTPase inhibition by R-ketorolac, a targeted microarray analysis was performed. Preliminary results show an alteration to the gene expression profile of human cytoskeletal regulators in response to ketorolac treatment. These effects may be due to inhibition of Rac1 and Cdc42 directly or through upstream or downstream inhibition. This analysis also provides biomarkers that can be used to analyze tumor tissues from primary patients and animal studies. Together, these findings indicate that R-ketorolac is a novel inhibitor of Rac1 and/or Cdc42, and inhibit cellular processes necessary for ovarian cancer metastasis. The mechanism behind ketorolac inhibition will require further investigation. In the future, this drug may offer benefit to ovarian cancer patients through inhibition of these GTPase targets

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 910. doi:1538-7445.AM2012-910
Abstract 923: Interrelations between roles of phospholipase C-gamma 1 inhibition, mTOR and glycolytic enzymes in growth and survival of glioblastoma cells
Authors: Jain Aditi , Lai James C.K. , Chowdhury Golam MI , Behar Kevin , Bhushan Alok
Published: August 2012

Glioblastoma multiforme (GBM) is a deadly and a frequently occurring brain tumor in humans. Patients with this disease survive on an average for 12-14 months after diagnosis. Conventional approaches to treat the cancer are not effective in improving patient survival. Thus, it is imperative to seek new drug targets and therapies that could effectively treat brain tumors and enhance patient survival. Phospholipase C-gamma 1 (PLCα1) plays an important role in regulating intracellular calcium stores and acts as a point of convergence in several cell signaling cascades. Inhibition of PLCα1 is known to decrease cell differentiation, invasion and motility in several cancers. We previously demonstrated inhibition of PLCα1 blocks invasion of glioma cells. In this study, we investigated the effects of PLCα1 inhibition on cell viability, cell signaling and metabolism in brain tumor (U-87 MG) cells. We investigated the hypothesis that inhibition of PLCα1 blocks cellular progression of U-87 MG. U73122, an inhibitor of PLCα1, induced a dose-related decrease in survival of U-87 MG cells, with a maximal effect at 2 µM: this finding correlated with the U73122-induced decrease in expression of lactate dehydrogenase, a protein important in U-87 MG cell survival and metabolism. Moreover, U73122 was effective in enhancing the cytotoxic potential of temozolomide, a modestly effective drug used currently for the treatment of glioblastoma. Western blot analysis of U-87 MG cells treated with U73122 at concentrations between 0.5 and 2 µM showed biphasic effects on expression of phospho-ERK and mTOR, proteins involved in PLCα1 signaling as well as hexokinase II, an important glycolytic enzyme. Employing 1H-[13C]-NMR spectroscopy, we noted that treatment with 2 µM U73122 for 72 hours induced increased glycolytic flux in U-87 MG cells. Thus, our results suggest important mechanistic interrelations between PLCα1 signaling and roles of mTOR and glycolytic enzymes in regulating survival of brain tumor cells. Furthermore, our results also suggest that inhibition of PLCα1 may be exploited in combination with conventional therapies in treating patients with glioblastoma to improve their outcome.

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 923. doi:1538-7445.AM2012-923
Abstract 932: Selective requirement of BH3-only proteins for apoptosis induced by targeted therapies in colon cancer cells and xenografts
Authors: Zheng Xingnan , He Kan , Sun Jing , Sun Quanhong , Brown Matthew F. , Zhang Lin , Yu Jian
Published: August 2012

Constitutive activation of pro-survival kinases has become a promising target of recently developed small molecules, while their biomarkers and resistance mechanisms remain largely unknown. In this study, we investigated the role of several BH3-only proteins PUMA, Bim and Noxa in apoptosis and growth suppression induced by different classes of targeted agents, including selective small molecule inhibitors to c-Met, IGFR, Hsp90, VEGFR and non selective kinases inhibitors in colon cancer cells and xenografts. Using isogenic colon cancer cells with targeted deletion in PUMA, Bim or Noxa, we demonstrated universal and persistent PUMA induction by all of these agents, which is mediated by either p53-dependent or -independent mechanisms. PUMA deficiency led to impaired apoptosis and caspase activation in colon cancer cells, and significantly blocked tumor cell apoptosis and therapeutic responses to these agents in xenografts. On the contrary, modulation of upstream signaling such as phosphorylation of PI3K/AKT was transient and involves diverse transcription factors. Interestingly, only a small subset of agents induced the expression of Bim or Noxa, or required Bim or Noxa for apoptosis induction. Moreover, small molecule BH3 mimetics, or enhanced PUMA levels resulted from another drug sensitized colon cancer cells to apoptosis induced by majority of these agents. Our results establish a critical role of the mitochondrial pathway and BH3-only proteins in mediating sensitivity of colon cancer cells to a wide variety of targeted-agents, and shed light on resistance mechanisms. In light of recent data on BH3-only proteins in therapy-induced apoptosis in other tumor types, our data suggest that modulations of selected BH3-only proteins, rather than their steady-state levels, might sever as potential biomarkers for predicting therapeutic responses in both treatment-naïve and pretreated patients, and provide a rationale for combination therapy in clinical trials. These novel preclinical findings can help guide future development and clinical use of targeted agents. Key words: kinase inhibitors; PUMA; Bim; Noxa; apoptosis; resistance mechanisms, 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 932. doi:1538-7445.AM2012-932
Abstract 94: Epigenetic silencing of CDO1 sustains viability of breast cancer cells via the reduction of cellular ROS
Authors: Jeschke Jana , O'Hagan Heather , Zhang Wei , Calmon Marilia F. , Dhir Mashaal , van Neste Leander , Bijsmans Ingrid , Gabrielson Edward , Schuebel Kornel E. , Baylin Stephen B. , Winterpacht Andreas , Herman James G. , Ahuja Nita
Published: August 2012

Approaches to analyze genome-wide methylation changes have become an extraordinary useful tool to identify thousands of new candidate hypermethylated genes in cancer. Numerous comprehensive approaches have been initiated to begin to understand the biological significance of the vast amount of methylation data generated and by this, novel tumor suppressor genes, biomarkers for early detection and prognosis prediction of cancer, and molecular mechanisms underlying tumor growth control have been discovered. In this study, we explore the candidate hypermethylated gene Cysteine Dioxygenase Type 1 (CDO1), which was recently identified in breast cancer using a functionally proven genome-wide gene expression approach. Here, we show that the epigenetic inactivation of CDO1 enhances tumor growth and sustains viability of breast cancer cells via the reduction of cellular ROS. Moreover, we observed a cancer stage-dependent increase in CDO1 methylation frequency (DCIS: 50%, stage 1-2: 65% and stage 3-4: 90%) that coincides with elevated oxidative stress levels in advanced cancers. These findings support the hypothesis that cancer cells upregulate their antioxidant capacity in adaptation to intrinsic oxidative stress. Lastly, we correlated CDO1 methylation status with clinicopathologic patient characteristics in a cohort of 186 patients. Methylation of CDO1 is significantly associated with prognostic parameters such as tumor stage, lymphovascular and perinodal invasion and predicts worse patient outcome.

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 94. doi:1538-7445.AM2012-94
Abstract 948: IGF-I receptor expression is associated with stage and has therapeutic activity in human biliary tract cancers
Authors: Adachi Yasushi , Yamamoto Hiroyuki , Ohashi Hirokazu , Taniguchi Hiroaki , Nosho Katsuhiko , Suzuki Hiromu , Arimura Yoshiaki , Endo Takao , Imai Kohzoh , Carbone David P. , Shinomura Yasuhisa
Published: August 2012

Insulin-like growth factor (IGF)-I receptor (IGF-IR) signaling is required for carcinogenicity and progression of several cancers but the function of this pathway and its utility as a therapeutic target has not been well studied in biliary tract carcinomas. We investigated the immunohistochemical expression of elements of the IGF axis, matrilysin, overexpression of p53, and the methylation status of the IGFBP-3 promoter in 80 surgically resected biliary tract carcinomas. We also assessed the effect of IGF-IR blockade on signal transduction, proliferation, and survival in 3 biliary tract cancer cell lines using a new tyrosine kinase inhibitor, BMS-536924, and dominant negative IGF-IR (IGF-IR/dn). The effects of IGF-IR blockade was also studied in nude mouse xenografts models. IGF-I was expressed in 60% and IGF-II in 50% of tumors and high expression was associated with tumor size. IGF-IR was expressed in 69% of the cases and was associated to advanced stage and matrilysin expression. Hypermethylation of the IGFBP-3 promoter was detected in 41% and was inversely correlated with p53 expression. BMS-536924 blocked autophosphorylation of IGF-IR and both Akt and ERK activation by both IGF-I and insulin. BMS-536924 suppressed proliferation and tumorigenicity in vitro in a dose-dependent fashion. This inhibitor up-regulated chemotherapy-induced apoptosis in a dose dependent fashion. Moreover, IGF-IR blockade was effective against tumors in mice. IGF-IR might identify a subset of biliary tract cancers with a particularly aggressive phenotype and is a candidate therapeutic target in this disease. BMS-536924 may have significant therapeutic utility.

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 948. doi:1538-7445.AM2012-948
Abstract 952: The SCF F box protein, Skp2, is a key component of an E3 ubiqutin ligase that governs estrogen receptor ≤ stability
Authors: Zhou Wen , Sun Jun , Slingerland Joyce M.
Published: August 2012

Breast carcinoma is the most common cancer among women in developed countries, and about 70% of these tumors express estrogen receptor ≤ (ERα). ERα is a transcription factor and master regulator of estrogen stimulated proliferation and its expression indicates potential for response to estrogenic stimulation. A majority of ERα positive breast cancers initially respond well to selective estrogen receptor modulators (such as tamoxifen) or to aromatase inhibitors. Understanding the regulation of ERα levels and its role in transcription of estrogen driven genes is thus highy germane to breast cancer therapy. There is evidence that for many transcription factors, activation is linked to factor degradation. Moreover, estrogen stimulation is known to activate ERα proteolysis. Given the importance of estrogen as a driver of breast cancer progression, we have investigated mechanisms governing ERα proteolysis. S phase kinase-associated protein 2 (Skp2) is an F box component of a multi-protein SCF ubiquitin ligase that acts on multiple substrates. Levels of Skp2 have been reported to be inversely related with the levels of ERα in breast cancer. Here we report that SCFSkp2, comprised of Skp2, in association with Skp1, Cul1 and Rbx1, is an E3 ubiquitin ligase for ERα. Ectopic expression of dominant negative Cul1 increases ERα levels by impeding ERα degradation in breast cancer cells. Knockdown of Skp2 impairs estrogen-triggered ERα proteolysis, while ectopic Skp2 expression decreased ERα stability. We show that Skp2, Skp1, Rbx1 and Cul1 co-precipitate with cellular ERα and the formation of this ERα/SCFSkp2 complex is cell cycle regulated and parallels CDK2 activation. We also show ER is an in vitro substrate that is ubiquitylated and degraded by SCFSkp2. The involvement of CDK2-dependent ERα phosphorylation in estrogen activated ERα/SCFSkp2 binding, ERα proteolysis and the functional consequences of this on ERα transcriptional activity are under investigation. These data suggest that Skp2 plays an important role in the regulation of ERα stability, and potentially in the biologic action of this key steroid hormone receptor 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 952. doi:1538-7445.AM2012-952
Abstract LB-1: Discovery and optimization of orally bioavailable, selective and potent ATP-independent Akt inhibitors
Authors: Chan Thomas C.K. , Ashwell Mark A. , Lapierre Jean-Marc , Brassard Christopher , Bull Cathy , Cornell-Kennon Susan , Eathiraj Sudharshan , France Dennis S. , Hill Jason , Koerner Steffi , Kelleher Eoin , Kizer Darin , Liu Yanbin , Link Jeff , Makhija Sapna , Moussa Magdi , Namdev Nivedita , Nicewonger Robert , Uppalapati Uma , Palma Rocio , Szwaya Jeff , Tandon Manish , Vensel David , Volak Laurie , Volckova Erika , Westland Neil , Wu Hui , Yang Rui-Yang
Published: August 2012

Herein we describe the implementation of a biochemical and biophysical screening strategy to discover small molecules that inhibit Akt through a mechanism distinct from ATP-competitive inhibitors. A series of novel derivatives of the core scaffold 3H-imidazo[4,5-b]pyridine were identified and optimized. These Akt inhibitors demonstrated potent inhibition of intracellular Akt and downstream targets including PRAS40 activation in vitro. Pharmacodynamic and pharmacokinetic studies in vivo demonstrated the effectiveness of the series at inhibiting the activation of Akt and an additional downstream effector (p70S6) following oral dosing in mice. Co-crystallization studies with un-phosphorylated Akt1 revealed that as a consequence of binding these novel, potent and selective, ATP-independent inhibitors the ATP binding cleft is occupied by non-polar residues which are associated as tight clusters. The cleft is closed with a ‘hydrophobic lock’ which may function to sterically exclude the binding of both ATP and ATP-competitive inhibitors.

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 LB-1. doi:1538-7445.AM2012-LB-1
Abstract LB-106: A novel TCL1-Tg:p53−/− mouse model of human CLL
Authors: Liu Jinyun , Chen Gang , Feng Li , Zhang Wan , Pelicano Helene , Lu Weiqing , Amin Hesham , Keating Michael , Croce Carlo M. , Huang Peng
Published: August 2012

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the United States and Europe. CLL patients with loss of p53 due to chromosome 17p deletion often exhibit more malignant disease phenotype, are refractory to standard treatment, and have poor clinical outcomes. Although there are several mouse models that resemble the chronic disease processes of CLL, no animal model has been reported that mimic the aggressive disease phenotype of CLL with loss of p53. To facilitate the investigation of the biology of aggressive CLL with loss of p53 and the underlying mechanisms, we generated a mouse model with Eu-TCL1-Tg:p53−/− genotype by crossing the Eu-TCL1-Tg mice with p53 knockout mice. The Eu-TCL1-Tg:p53−/- mice developed CLL disease at 3-4 months, significantly earlier than the parental Eu-TCL1-Tg mice that developed CLL disease at 8-12 months. Flow cytometry analysis showed that the IgM+/CD5+ cell population appeared in the peritoneal cavity, bone marrow, and the spleens of Eu-TCL1-Tg:p53−/- mice significantly earlier than that of the parental Eu-TCL1-Tg mice. Massive infiltration and accumulation of leukemia cells were found in the spleen, liver, and peritoneal cavity. In vitro study showed that the leukemia cells isolated from the Eu-TCL1-Tg:p53−/- mice were more resistant to fludarabine treatment than the leukemia cells isolated from spleens of TCL1-Tg mice. Interestingly, TUNEL assay revealed that there was higher apoptotic cell death found in the TCL1-Tg spleen tissue compared to the spleens of the Eu-TCL1-Tg:p53−/- mice, suggesting that the loss of p53 compromises the apoptotic process in vivo, and this might in part explain the drug resistant phenotype of CLL cells with 17p deletion. Further molecular analysis showed that the expression of MCL-1, a key survival molecule for CLL, was significantly increased at the mRNA and protein levels in the leukemia cells isolated from Eu-TCL1-Tg:p53−/- mice, which seemed to be associated with the abnormal expression of certain microRNAs including miR15a and miR-16. Overall, the Eu-TCL1-Tg:p53−/- mice display a disease phenotypes that resemble human CLL with 17p deletion, and represent a useful animal model for mechanistic study as well as evaluation of in vivo therapeutic efficacy of anti-CLL 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 LB-106. doi:1538-7445.AM2012-LB-106
Abstract LB-154: Nuclear export of CALM-AF10 is essential for leukemogenesis
Authors: Conway Amanda E. , Scotland Paula B. , Lavau Catherine P. , Wechsler Daniel S.
Published: August 2012

Background: The t(10;11) chromosomal translocation gives rise to the CALM-AF10 fusion gene and is recurrently found in patients with aggressive and difficult-to-treat hematopoietic malignancies (AML and T-ALL). CALM-AF10 leukemias are characterized by upregulation of Hoxa cluster genes and a reduction in H3K79 methylation. The native AF10 protein localizes to the nucleus, while native CALM protein is found predominantly in the cytoplasm. It has been shown that the OM-LZ domain of AF10 interacts with the histone methyltransferase, Dot1L, and that this interaction is necessary for CALM-AF10-mediated transformation. Although it is known that CALM functions as an accessory endocytic protein, the precise role of CALM in leukemogenesis is unclear. Objective: To determine the role of CALM in CALM-AF10-mediated transformation in an effort to identify novel therapeutic targets. Results: Through structure-function analyses, we determined that a minimal region of CALM (aa 520-583) is critical for CALM-AF10-mediated transformation of murine hematopoietic progenitor cells (HPCs). Further analysis of this sequence identified a nuclear export signal (NES) encoded by CALM aa 544-553. The CALM NES mediates the cytoplasmic localization of CALM-AF10; point mutation of the CALM NES (NES*) results in exclusive CALM(NES*)-AF10 accumulation in the nucleus. In contrast to CALM-AF10, transduction of primary murine HPCs with CALM(NES*)-AF10 fails to cause in vitro transformation. Fusion of an 18 aa peptide that includes the CALM NES in frame with AF10 (NESCALM-AF10) is sufficient to induce transformation in vitro and leukemogenesis in vivo. Leukemias induced by NESCALM-AF10 recapitulated the phenotype of CALM-AF10 leukemias, including aberrant Hoxa cluster upregulation and decreased H3K79 methylation. Strikingly, fusion of the NES from different proteins, such as PKI-α and APC, to AF10 also conferred cytoplasmic localization and resulted in transformation in vitro. Finally, human CALM-AF10 leukemia cell lines (U937 and P31-FUJI) display increased sensitivity to a compound that inhibits nuclear export, Leptomycin B. Conclusions: We have determined that a CALM-derived nuclear export signal is both necessary and sufficient for CALM-AF10-mediated transformation. These findings reveal a novel mechanism by which nuclear export of CALM-AF10 mediates leukemogenesis. We postulate that nuclear export inhibitor (NEI) compounds may offer new therapeutic possibilities for patients with aggressive CALM-AF10 leukemias.

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 LB-154. doi:1538-7445.AM2012-LB-154
Abstract LB-162: DNA-damage foci persistence and accelerated senescence as determinants of radiosensitization by glycolysis inhibitors
Authors: Efimova Elena V. , Labay Edwardine , Mauceri Helena J. , Darga Thomas E. , Ulanovskaya Olesya A. , Kozmin Sergey A. , Weichselbaum Ralph R. , Kron Stephen J.
Published: August 2012

One of the most striking characteristics of cancer cells is their altered glucose metabolism. Many cancer cells display a dramatic elevation in glucose utilization, independent of the availability of oxygen or the activity of oxidative phosphorylation. Cancers often display the Warburg effect, wherein glycolysis drives fermentation of pyruvate to lactate even under aerobic conditions. Aerobic glycolysis has been widely investigated and it is now considered a metabolic hallmark of transformation and a key driver for cancer cell proliferation, malignancy, metastasis, and therapeutic resistance. En route to cancer, pre-malignant cancer cells have to overcome cellular senescence which is recognized as a barrier for tumorigenesis. Recent data link both replicative and accelerated senescence to persistent DNA damage signals that arise from domains of modified chromatin at sites of un-repairable double strand breaks. Our prior work has established the kinetics of resolution of these chromatin domains, dubbed ionizing radiation induced foci (IRIF), and resulting effects on accelerated senescence as determinants of radiation sensitivity and as a target that can sensitize cancer cells to genotoxic therapy. To obtain probes that impinge on the DNA damage response and senescence, we developed a cell based assay for high throughput, high content screening based on the detection of IRIF persistence. Screening over 2500 drugs, including natural products and drug-like compounds identified known DNA damaging agents as well as novel candidates. To gain mechanistic insight, we tested these “hits” in combination with the mitochondrial inhibitor antimycin A and discovered several that blocked ATP synthesis. Combining bona fide glycolytic pathway inhibitors with radiation enhanced IRIF persistence and accelerated senescence in vitro. The glucokinase inhibitor 2-DG increased IRIF persistence and senescence after irradiation of tumor xenografts. These data suggest a critical role for aerobic glycolysis in the proliferation and survival of cancer cells to prevent stress-induced premature senescence, specifically by blocking the formation of DNA damage foci and/or preventing their persistence. Rather than simply satisfying energy needs, aerobic glycolysis likely serves an important survival and immortalization function for cancer cells. As such, targeting the Warburg effect to promote cancer cell senescence appears to be an attractive strategy for therapeutic intervention, particularly in combination with genotoxic 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 LB-162. doi:1538-7445.AM2012-LB-162
Abstract LB-163: Modulation of glucose metabolism by CD44 contributes to antioxidant status and drug resistance in cancer cells
Authors: Tamada Mayumi , Suematsu Makoto , Saya Hideyuki
Published: August 2012

An increased glycolytic flux accompanied by activation of the pentose phosphate pathway (PPP) is implicated in chemoresistance of cancer cells. In this study, we found that CD44, a cell surface marker for cancer stem cells, interacts with pyruvate kinase M2 (PKM2) and thereby enhances the glycolytic phenotype of cancer cells that are either deficient in p53 or exposed to hypoxia. CD44 ablation by RNA interference increased metabolic flux to mitochondrial respiration and concomitantly inhibited entry into glycolysis and the PPP. Such metabolic changes induced by CD44 ablation resulted in marked depletion of cellular reduced glutathione (GSH) and increased the intracellular level of reactive oxygen species (ROS) in glycolytic cancer cells. Furthermore, CD44 ablation enhanced the effect of chemotherapeutic drugs in p53-deficient or hypoxic cancer cells. Taken together, our findings suggest that metabolic modulation by CD44 is a potential therapeutic target for glycolytic cancer cells that manifest 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 LB-163. doi:1538-7445.AM2012-LB-163
Abstract LB-168: A hexane fraction of American ginseng suppresses colon cancer associated with colitis
Authors: Poudyal Deepak , Cui Xiangli , Hofseth Anne B. , Chumanevich Alena , Chumanevich Alexander A. , Wargovich Michael J. , Windust Anthony , Nagarkatti Mitzi , Nagarkatti Prakash , Hofseth Lorne J.
Published: August 2012

Patients with Ulcerative Colitis (UC) have a high risk of colon cancer. We have recently shown American Ginseng (AG) suppresses colitis, and prevents colon cancer in mice. In the present study we isolated a Hexane Fraction of AG and found this to have particularly potent anti-oxidant and pro-apoptotic properties. The Hexane Fraction of AG was effective in inducing apoptosis of human epithelial colon cancer cell, HCT-116 and inflammatory cells. As well, this fraction was shown to suppress azoxymethane (AOM)/DSS-induced colon cancer. We performed two studies with mice: a short term (Day 35) and long term (Day 50) cancer prevention study. Mice fed the Hexane fraction of AG had significantly less inflammatory and ulcerative lesions, as well as cancerous lesions compared with the vehicle-treated group in both the short and long-term cancer prevention studies. Results are consistent with the hypothesis that the Hexane fraction of AG has anti-inflammatory and anti-cancer properties, and prevents the progression of colon cancer in AOM/DSS mouse model. Interestingly, at Day 35, following isolation of CD45- epithelial cells from colons of mice treated with either AOM+DSS+Vehicle or AOM+DSS+Hexane fraction of AG, there was a 24% increase in the putatative tumor suppressor miRNA-16 with treatment with the Hexane fraction of AG. When looking at putative miRNAs with oncogenic properties (miRNA-21 and -155), levels were decreased in epithelial cells by 25% and 12% respectively in the Hexane fraction of AG-treated mice. This study provides additional pre-clincal data, and mechanistic studies that support the possible use of this complementary and alternative medicine in the treatment of colitis, and the prevention of colon cancer associated with colitis.

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 LB-168. doi:1538-7445.AM2012-LB-168
Abstract LB-170: A role of sphingosine kinase 1 in peritoneal macrophages on the early stages of colon carcinogenesis
Authors: Kawamori Toshihiko , Furuya Hideki , Shimizu Yoshiko , Yamada Paulette M.
Published: August 2012

Our previous studies indicate that the Sphingosine kinase 1 (SphK1)/Sphingosine 1-phosphate (S1P) pathway mediates colon carcinogenesis at least by regulating COX-2 expression and prostaglandin E2 (PGE2) production. However, the mechanisms by which this pathway regulates colon carcinogenesis are still unclear. First, we show that SphK1 deficient mice significantly attenuated azoxymethane (AOM)-induced colon carcinogenesis as measured by colon tumor incidence, multiplicity, and volume. We found that AOM activates peritoneal macrophages to induce SphK1, COX-2, and TNF-α expression in WT mice. Interestingly, SphK1 KO mice revealed significant reduction of COX-2 and TNF-α expression from AOM-activated peritoneal macrophages, suggesting that SphK1 regulates COX-2 and TNF-α expression in peritoneal macrophages. Finally, we found that inoculation of WT peritoneal macrophages “rescued” the carcinogenic effect of AOM in Sphk1 KO mice as measured by aberrant crypt foci (ACF) formation, preneoplastic lesions of colon cancer, indicating that SphK1 expression in peritoneal macrophages is required in the early stages of colon carcinogenesis when induced by AOM. These results suggest that SphK1 expression plays a pivotal role in the early stages of colon carcinogenesis through regulating COX-2 and TNF-α expression from activated peritoneal macrophages.

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 LB-170. doi:1538-7445.AM2012-LB-170
Abstract LB-271: Loss of the transcription factor REST promotes breast cancer tumorigenicity in a LIN28-dependent manner
Authors: Gunsalus Kearney T. W. , Wagoner Matthew P. , Meyer Kassondra M. , Potter Wyatt B. , Kim Soyoung , Schoenike Barry , Alexander Caroline M. , Freidl Andreas , Roopra Avtar
Published: August 2012

About 20% of the nearly 300,000 American women diagnosed with breast cancer this year will have a particularly aggressive form of the disease characterized by a lack of the transcription factor REST. These “RESTless” tumors are associated with particularly poor patient prognosis; 50% of patients with RESTless tumors experience disease recurrence within the first three years post-diagnosis, compared with less than 20% of patients whose tumors still express REST. Here, we use cell culture and xenograft models of RESTless breast cancer to demonstrate that REST loss causes the increased aggression of these tumors. Using lentiviral delivery of shRNAs, we generated several breast cell lines with a stable REST knockdown (“RESTlow” cells; a non-targeting shRNA was used to generate control “RESTnorm” cells). We find that REST knockdown increases focus formation in MCF10A, MCF7 and MDA-MB-231 cells. RESTlow MCF10A and MCF7 cells also show enhanced anchorage-independent growth in soft agar. We performed xenograft experiments with RESTlow and RESTnorm MCF7 cells; the RESTlow cells have a greatly enhanced capacity to form tumors in nude mice. We further explore the molecular mechanism underlying the tumorigenicity of cells lacking REST. We demonstrate that REST is a direct transcriptional repressor of the RNA binding protein LIN28 in breast cancer cell lines; as predicted, LIN28 expression is increased upon REST knockdown. Knockdown of LIN28 in RESTlow cells ablates the ability of RESTlow MCF7 cells to form foci in culture, colonies in soft agar, and tumors in nude mice. We therefore conclude that the aberrant upregulation of LIN28 that occurs when REST is lost is required for the tumorigenicity of RESTlow cells. Finally, we show that in human RESTless breast tumors, LIN28 expression is significantly increased. This is the first report to demonstrate that REST loss causes increased tumor aggression and to propose an underlying mechanism for the tumorigenicity of cells lacking REST.

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 LB-271. doi:1538-7445.AM2012-LB-271
Abstract LB-310: Changes in the gene expression profile of A375 human melanoma cells induced by over-expression of multifunctional pigment epithelium-derived factor
Authors: Jimenez Benilde , Orgaz Jose L.
Published: August 2012

Pigment epithelium-derived factor (PEDF) is a broad-spectrum angiogenesis inhibitor that displays potent anti-metastatic activity in multiple tumor types. We have previously shown that PEDF prevents primary tumor growth and metastatic spread of human melanoma in mouse experimental models. Consistent with these observations, PEDF expression is lost at the late stages of melanoma progression, allowing melanoma cells to become angiogenic, migratory and invasive. PEDF's ability to modify the interplay between the host and tumor tissues strongly supports its use as a therapeutic agent for the treatment of metastatic melanoma. However, transition to the clinic requires a more detailed knowledge of the molecular mechanisms underpinning PEDF's activity. In this study we describe changes in the gene expression profile of A375 human melanoma cells induced by PEDF over-expression. PEDF modulated diverse categories of genes known to be involved in angiogenesis and migration. It downregulated cytokines like interleukin 8 and extracellular matrix proteins like collagen IV, while it upregulated fibronectin. Multiple transcripts previously described as contributing to the acquisition of malignant phenotype by melanoma were also diminished by PEDF over-expression, among which we validated galectin 3 and jagged 1. Additionally, PEDF downregulated S100β and melanoma inhibitory activity (MIA), which are widely used in the pathological diagnosis of melanoma. Interestingly, PEDF increased the expression of melanophilin and decreased rab27A, which are relevant targets for melanosome transport; suggesting that PEDF could directly impinge on melanocytic lineage-specific processes. Our study identifies new molecular targets and signaling pathways that may potentially contribute to determine PEDF's ability to restrict the aggressiveness of A375 human melanoma 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 LB-310. doi:1538-7445.AM2012-LB-310