bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract LB-215: Inhibition of Polo-like kinase 4 as an anti-cancer strategy
Authors: Mason Jacqueline , Wei Sam , Luo Xunyi , Nadeem Vincent , Kiarash Reza , Huang Ping , Awrey Don , Leung Genie , Beletskaya Irina , Feher Miklos , Forrest Bryan , Laufer Radek , Sampson Peter , Li Sze-Wan , Liu Yong , Lang Yunhui , Pauls Henry , Mak Tak , Pan James Guohua
Published: June 2012

Polo-like kinase 4 or PLK4 is a member of a conserved family of serine/threonine protein kinases that regulate multiple cellular processes, such as cell division and checkpoint regulation of mitosis. These kinases are often deregulated in cancer. PLK4 is the most structurally divergent PLK, localizes to centrosomes and is a critical regulator of centriole duplication. Over-expression of PLK4 leads to centrosome amplification and results in chromosome instability (CIN), a common characteristic observed in many types of cancers. We found that PLK4 is upregulated in breast cancer, specifically in the basal-like subtype. PLK4 expression is induced by hypoxia and suppressed by p53 in cancer cells. Consistent with this observation, PLK4 expression in cancer cells is upregulated when they are implanted and grown as xenografts in vivo. Furthermore, RNAi-mediated depletion of PLK4 inhibits the growth of cancer cells, but not normal cells (HMEC), in vitro, and tumor growth in vivo. Interestingly, siRNA knockdown of PLK4 sensitizes cancer cells to hypoxia. These findings suggest that targeting PLK4 may be a good therapeutic strategy in treating certain cancers. To this end, we initiated a discovery program that resulted in the identification of potent PLK4 inhibitors. These novel inhibitors are potent anti-prolifeartives, cause loss of mitotic checkpoint followed by apoptotic cell death, and suppress tumor growth in xenograft models. Mechanistically, inhibition of PLK4 suppresses phosphorylation of PLK4 and Histone H3, leads to failure of centrosome clustering and formation of multipolar spindles. Interestingly, breast cancer cell response to PLK4 inhibition appears to differ among subtypes of breast cancer cells and to be influenced by receptor and mutation status, such as ER and PTEN. Since multipolar division in cancer cells is not viable, due to massive missegregation of chromosomes, inhibition of PLK4 and formation of multipolar division followed by cell death may be a unique strategy for killing cancer cells. Implications of these findings in treating cancer will also be discussed.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-215. doi:10.1158/1538-7445.AM2011-LB-215
Abstract LB-223: Dissecting the therapeutic determinants of MET inhibition in Glioblastoma: HGF-autocrine loop predicts sensitivity to MET inhibitor
Authors: Xie Qian , Bradley Robert , Kang Liang , Koeman Julie , Worschech Andrea , De Giorgi Valeria , Wang Ena , Kefene Lisa , Su Yanli , Essenburg Curt , Kaufman Dafna , DeKoning Tom , Enter Mark , J.O'Rourke Timothy , Marincola Francesco , Vande Woude George F.
Published: June 2012

Due to its invasive nature, glioblastoma (GBM) is the most aggressive brain cancer. Hepatocyte growth factor (HGF) binds to MET tyrosine kinase receptor and induces invasive tumor growth. As MET inhibitors are entering clinical trials against several types of cancer including GBM, it is compelling to identify therapeutic determinants which could indicate which patient subsets are suitable for this therapy. We investigated in vivo four types of GBM models for their sensitivity to MET (SGX523*) or EGFR (erlotinib*) inhibitors: 1) Tumors sustained by an HGF-autocrine loop; 2) tumors displaying paracrine HGF tumor growth; and 3) tumors with polysomy MET amplification. 4) In addition, GBM tumors with epidermal growth factor receptor (EGFR) amplification were included, as this occurs frequently in GBM patients and often in association with MET aberrancy. Of the four tumor types, we observed that HGF-autocrine loop expression correlates with p-MET levels in the HGF autocrine cell lines, which in turn are extremely sensitive to MET inhibition in vivo. Moreover, serum HGF levels in HGF-autocrine loop GBM xenografts correlate with MET inhibition. Paracrine HGF can enhance GBM growth in vivo, but they were not significantly sensitive to MET inhibition. In type 4, EGFR VIII amplification predicted sensitivity to erlotinib, but MET polysomy in the same tumor did not display MET activity and the cells did not show sensitivity to MET inhibition. We conclude that HGF-autocrine loop GBM tumors bear an activated MET signaling pathway that may be used to predict sensitivity to MET inhibitors in GBM patients. However, targeting MET alone may not be sufficient for treating GBM and the combination of MET with other RTK inhibitors, especially EGFR inhibitors should be considered.

*SGX523, a selective small molecule MET inhibitor, was obtained from Eli Lilly and Company, Indianapolis IN.

*Erlotinib inhibits EGFR and was a generous gift from OSI Pharmaceuticals, Long Island N.Y.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-223. doi:10.1158/1538-7445.AM2011-LB-223
Abstract LB-278: Transcriptomic profiling of castrate resistant prostate cancer cells: identification of transcription factors associated with androgen resistance
Authors: Prencipe Maria , Madden Stephen , O'Neill Amanda , Culhane Aedin , O'Connor Darran , Klocker Helmut , Gallagher William M. , Watson William
Published: June 2012

Locally advanced and metastatic prostate cancer are treated by hormone ablation therapy. However, despite an initial response, the majority of men relapse within 2–3 years to develop a castrate resistant disease for which there are no effective treatments; therefore defining the mechanisms of resistance represents a significant question.

Androgen-independent (AI) sublines were derived from the androgen-dependent (AD) LNCaP cells. Previous studies in our laboratory have shown a complex interplay between changes in pro and anti-apoptotic proteins in the development of this resistance. Manipulating individual genes has only minor alterations in the resistant phenotype so we hypothesise that targeting the central signalling pathways and transcription factors (TFs) would represent a better therapeutic targeting approach.

We have undertaken a transciptomic analysis of the LNCaP parental (AD), LNCaP Abl (AI) and Hof (AI) cell lines, using the Affymetrix HG U133 Plus 2.0 GeneChip. Using a combination of correspondence analysis, between group analysis and co-inertia analysis, we have generated a transriptomic profile showing 900 genes associated with androgen resistance. Most importantly, we have predicted a list of TFs including HSF1, CDP, VDR-RXR, SRF and PBX1, which may be responsible for the differential gene expression observed in the AI compared to the AD cells. Taqman validation of 32 genes, including 6 TFs, has confirmed our gene chip results. Further validation of VDR-RXR and SRF activity was performed using luciferase assays. We are currently focusing on SRF, which has recently been associated with prostate cancer development (1). We have confirmed its up-regulation in the AI cell lines by WB.

Due to the heterogeneous nature of prostate cancer and the complex changes associated with the development of androgen resistance, the upstream TFs may represent better therapeutic targets to reverse this resistance.

Reference

1. Gorlov et al. Prioritizing genes associated with prostate cancer development. BMC Cancer 2010, 10:599

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-278. doi:10.1158/1538-7445.AM2011-LB-278
Abstract A14: Invalidation of the inflammasome within breast tumor microenvironment impairs tumor growth
Authors: Guey Baptiste , Goutagny Nadege , Puisieux Isabelle , Caux Christophe , Tschopp Jurg , Renno Toufic , Pétrilli Virginie
Published: June 2012

Tumor microenvironment plays an essential role in modulating and supporting tumor growth. Solid tumors are frequently infiltrated with innate immune cells as illustrated by the strong macrophages infiltration observed in breast tumors. In fact, infiltrating macrophages in breast tumors are associated with poor prognosis. IL-1beta (IL-1 b) is a proinflammatory cytokine produced mostly by macrophages and dendritic cells which detection in advance breast tumor stage is also correlated with bad prognosis. Furthermore, mouse studies using the orthotopic implantation of the mammary tumor cell line 4T1 have suggested a role for IL-1b in tumor growth and vascularization. IL-1b is a peculiar cytokine as its production is tightly controlled. First, proinflammatory signals induce the production of the proIL-1 b. To be active, the cytokine has to be cleaved by the caspase-1 within a complex named the inflammasome. Finally the cleaved cytokine is secreted outside the cells. By and large, the inflammasome is composed of a scaffold receptor, for instance NLRP3, an adaptor, ASC, and caspase-1. The NLRP3 inflammasome is mainly expressed by macrophages and dendritic cells and gets activated upon detection of pattern-associated molecular pattern but also danger-associated molecular pattern such as extracellular ATP or uric acid. As the inflammasome controls the biological activity of IL-1b, we speculated that the inflammasome should play an important role in the breast tumor microenvironment. To test our hypothsesis, we used the mouse mammary model of breast cancer using orthotopic implantation of 4T1 cells within the mammary gland of either wild-type or inflammasome deficient mice. Our results show that tumor growth is delayed in caspase-1 deficient mice suggesting that the presence of the inflammasome in the tumor microenvironment supports tumor growth.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A14.
Abstract A15: Inflammation-dependent deregulation of the tumor suppressor Pdcd4
Authors: Schmid Tobias , Rübsamen Daniela , Blees Johanna S. , Bajer Magdalena M. , Milke Larissa , Schulz Kathrin , Henrich Curtis J. , McMahon James B. , Colburn Nancy H. , Brüne Bernhard
Published: June 2012

Tumor suppressor Pdcd4 was shown to inhibit the helicase activity of eIF4A and consequently to suppress the translation of mRNAs with structured 5′UTRs. As a result, Pdcd4 inhibits transformation, migration, and invasion in vitro and tumorigenesis in vivo. Recent reports indicate that Pdcd4 protein levels are attenuated in various human tumor types. Loss of Pdcd4 was not attributable to mutational inactivation, instead miR-21-dependent translational repression and p70S6K1-mediated, phosphorylation-dependent attenuation of Pdcd4 protein stability emerged as important mechanisms of Pdcd4 regulation.

In this study, we characterize the mechanism of Pdcd4 regulation under inflammatory, tumor-promoting conditions. Our data indicate that Pdcd4 protein is lost in human tumor cells exposed to an inflammatory environment generated by activated macrophages. Downregulation of Pdcd4 required activation of PI3K-mTOR-p70S6K1-signaling and was attributable to a markedly reduced Pdcd4 protein half-life resulting from increased proteasomal degradation. Functionally, Pdcd4 protein levels inversely correlated with AP-1 transactivation, migration, and invasion. Based on the proposed mechanism of Pdcd4 regulation, we further developed an assay to identify compounds interfering with tumor-promoter induced degradation of Pdcd4. Identified hit compounds will provide a source for novel, translation-oriented approaches for tumor therapies.

In summary, we suggest that p70S6K1-dependent phosphorylation and subsequent proteasomal degradation of Pdcd4 protein is a key mechanism in the regulation of the tumor suppressor Pdcd4 under inflammation-associated, tumor-promoting conditions. Consequently, we put forward stabilization of Pdcd4 as a novel tumor therapeutic approach and identify novel compounds disrupting Pdcd4's phosphorylation-dependent destabilization during tumorigenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A15.
Abstract A2: Differential dependency of human cancer cells on vascular endothelial growth factor-mediated autocrine growth and survival
Authors: Lee Jungwhoi , Lee Jungsul Lee , Yu Hana , Choi Chulhee , Choi Kyungsun
Published: June 2012

Analysis using the public microarray database Gene Expression Omnibus indicates significantly higher mRNA expression of VEGF and VEGFRs in colorectal cancer and high-grade astrocytoma but not in hepatocellular carcinoma compared to normal tissue. Human malignant astrocytoma cell lines (U251-MG and U373-MG) and HT-1080 fibrosarcoma cells expressed relatively higher levels of VEGF and VEGFRs compared to hepatocellular and colorectal cancer cell lines. Administration of exogenous VEGF-A induced cell growth in a dose-dependent fashion in astrocytoma and fibrosarcoma cells but not in colorectal and hepatocellular cancer cells. The blockade of VEGF inhibited cell survival only in U251-MG, U373-MG and HT-1080 cells. These results collectively suggest the role of autocrine VEGF signaling in various cancer cells and provide a basis for the variable clinical responses to antiangiogenic therapy observed in different types of malignancies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A2.
Abstract A20: Differential rates of proliferation and apoptosis observed in human cutaneous T-cell lymphoma cell lines, in response to treatment with 9-cis UAB30, a novel rexinoid analog
Authors: Verney Zoe M. , Atigadda Venkatram R. , Elmets Craig A. , Muccio Donald D. , Grubbs Clinton J.
Published: June 2012

Cutaneous T-cell lymphoma (CTCL) designates a heterogeneous group of malignancies, characterized by the infiltration and detection of transformed T-cell lymphocytes in the skin. Although there is no cure for CTCL, a wide range of treatment options have been developed for use in the clinical setting. Bexarotene, a retinoid X receptor (RXR) agonist or rexinoid, is a commonly used treatment modality for CTCL. However, documented increases in the levels of triglycerides of CTCL patients, resulting from treatment with bexarotene, point to concerns over the long-term use and efficacy of this anticancer agent. We have recently synthesized a novel rexinoid, 9-cis UAB30, which does not elevate triglycerides in vivo and have begun evaluating its use as a potential chemotherapeutic agent for the treatment of CTCL. In this study, we compared the efficacy of 9-cis UAB30 to that of bexarotene in reducing cell proliferation and inducing apoptosis, in the three human CTCL cell lines HH, MJ, and Hut78. A standard XTT assay was used to determine the rate of cell proliferation of CTCL cells. In all three lines, 9-cis UAB30 was equally and sometimes more effective than bexarotene at suppressing cell proliferation. Using an annexin V binding assay, we next analyzed the rate of apoptosis in these human CTCL lines. Interestingly, we observed the MJ cell line to be resistant to apoptosis, when treated with either compound. The HH cell line exhibited a similar increase in apoptosis, whether treated with 9-cis UAB30 or bexarotene. Finally, the Hut78 cell line showed a greater sensitivity to apoptosis, when treated with 9-cis UAB30 as compared to bexarotene. Taken together, these preliminary results indicate that 9-cis UAB30 appears to be equally if not more effective than bexarotene at suppressing cell proliferation and appears to exert differential effects on the rate of apoptosis that may be cell-line specific. These differential responses of human CTCL cells have implications for the development of next-generation, rexinoid-based therapies and reveal that 9-cis UAB30 may be a better alternative for the treatment of CTCL.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A20.
Abstract A27: Coordinate posttranscriptional regulation of breast cancer metastasis genes by RNA binding protein HuR
Authors: Techasintana Pat , Gubin Matthew , Magee Joseph D. , Calaluce Robert , Atasoy Ulus
Published: June 2012

Breast cancer is one of the most prevalent cancers worldwide. Distance metastasis is responsible for patient mortality. Therefore, understanding the mechanisms underlying tumor pathogenesis and metastasis is crucial for the development of novel therapies as well as preventive strategies for those who are prone to breast cancer. In contrast to transcriptional gene regulation, posttranscriptional control mechanisms of gene expression are poorly understood. Yet, many metastasis genes are regulated by RNA binding proteins (RBPs) at the levels of mRNA stability and translation.

The paraneoplastic antigen, HuR, is an RBP shown to regulate multiple genes that are significantly related to breast cancer metastasis by stabilizing target mRNAs and facilitating translation into proteins. Using novel techniques developed in our lab of RNA immunoprecipitation applied to microarrays (RIP-Chip) we identified novel discrete HuR-associated mRNAs in triple negative breast cancer and estrogen receptor positive breast cancer. Many of these HuR-associated mRNA transcripts were metastasis related.

We investigated the role of HuR in an aggressive triple-negative breast cancer metastatic cell line, LM2. The LM2 cells were retrovirally transduced with triple fusion reporter construct encoding thymidine kinase1, GFP and firefly luciferase to obtain in vivo and in vitro tracking capabilities. The cells were further transfected with plasmid containing HA-HuR or empty vector control to demonstrate the function of HuR in LM2. HuR over-expressing clones showed greater metastatic capability by in vitro matrigel invasion assay. Furthermore, athymic mice that were intravenously injected with HuR over-expressing LM2 cells had greater (335-fold more) tumor metastasis to the lungs than empty vector control injected group as measured by IVIS imaging. Mice injected with HuR over-expressing LM2 cells were more moribund and had greater mortality as compared with mice injected with empty vector control cells. These results suggest that HuR may play a role in breast cancer metastasis by stabilizing various pro-metastatic genes. The implications of this work are twofold. First, HuR RIP-Chip can be used to identify novel cancer relevant genes and second, interference with HuR function may ameliorate distant metastasis in breast cancer, potentially providing new therapeutic approaches for treatment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A27.
Abstract A34: Arf suppresses the growth and progression of Kras-driven lung tumors
Authors: Busch Stephanie E. , Gurley Kay E. , Moser Russell D. , Kelly-Spratt Karen S. , Kemp Christopher J.
Published: June 2012

Non-small cell lung carcinoma (NSCLC) is among the deadliest of human cancers, with an overall five-year survival rate of 10–20%. Activating mutations in the Kras proto-oncogene occur in approximately one-third of NSCLC patients, but tumor suppression in the lung remains poorly elucidated. The Cdkn2a locus, which houses both the p16lnk4a and Arf tumor suppressor genes, is frequently altered in NSCLC; however, the specific role of Arf in lung tumorigenesis has not been well characterized. Several lines of evidence indicate that Kras and other oncogenes induce the expression of Art, which in turn stabilizes p53 activity and arrests the growth of transformed cells. To determine the extent to which Arf suppresses NSCLC development in vivo, we employed the urethane chemical carcinogenesis model of Kras-driven NSCLC. We treated both wild-type and Arf-deficient mice with urethane and found that early-stage lung adenomas in wild-type mice robustly expressed Arf, In contrast to adenomas, malignant lung adenocarcinomas exhibited little induction of Art. Moreover, Arf-deficient mice exposed to urethane displayed accelerated lung tumor-associated morbidity and significantly increased lung tumor size compared to Arf wild-type and heterozygous littermates. Malignant progression of adenomas to adenocarcinomas was also markedly elevated in Arf-deficient mice. These data demonstrate that Arf functions as a barrier to tumor promotion and progression in a carcinogen model of Kras-driven NSCLC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A34.
Abstract A48: Effect of constitutive IGF2 overexpression on tumorigenicity of human ovarian carcinoma cells
Authors: Brouwer-Visser Jurriaan , Chao Suzan K. , Huang Gloria S.
Published: June 2012

Introduction: We previously described the association of high tumoral IGF2 expression with reduced disease-free survival in epithelial ovarian tumors. The purpose of this study was to determine the effect of IGF2 overexpression on the tumorigenicity of human ovarian cancer cells.

Methods: Expression constructs containing the full-length coding sequence of IGF2 or no insert (empty vector; EV) were made. HEY cells were stably transfected. Quantitative real-time PCR (of CDNA made from cell and xenograft RNA) and ELISA (of conditioned media) were performed to measure the IGF2 mRNA and protein expression levels, respectively. The relative IGF2 mRNA expression level was calculated by the 2−δδCt method with internal normalization to the cyclophilin B mRNA level. Tumorigenicity was evaluated in athymic nude mice by subcutaneous injection of 1×106 cells, with or without matrigel, followed by serial monitoring of in vivo tumor growth by digital caliper measurements. The two-tailed t-test was used to evaluate the significance of comparisons.

Results: The IGF2 mRNA level was 5604 ±617 fold-change higher in HEY-IGF2 cells relative to HEY-EV cells (P<0.05). The IGF2 secreted protein level was 1852 ng/ml per 100,000 HEY-IGF2 cells, and was not detectable in the conditioned media of HEY-EV cells. After 4 weeks, the mean tumor volume of subcutaneous xenografts following cell injection without matrigel was 181 ±53 mm3 versus 52 ±15 mm3 for HEY-IGF2 and HEY-EV, respectively (P<0.05, N=10 per group); and for cells injected with matrigel, the mean tumor volume was 1608 ±330 mm3 versus 705 ±95 mm3 for HEY-IGF2 and HEY-EV xenografts, respectively (P<0.05, N=6 per group). The tumor growth rate differed significantly between the HEY-IGF2 and HEY-EV xenografts (P<0.01). In the HEY-IGF2 xenografts, overexpression of IGF2 relative to HEY-EV xenografts was maintained.

Conclusions: Stable overexpression of IGF2 in HEY ovarian cancer cells and xenografts was achieved, and resulted in an increase in IGF2 protein secretion. IGF2 overexpression enhanced in vivo tumorigenicity of HEY ovarian cells, accompanied by an increased xenograft growth rate. Further evaluation is underway to fully characterize the mechanisms by which IGF2 overexpression promotes tumor growth.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A48.
Abstract A53: Genome-wide profile of somatic copy number alterations in Wilms tumor: Comparison between samples derived from patients with and without relapse
Authors: Krepischi Ana C.V. , Maschietto Mariana , Costa Silvia S. , Abreu Tales A. , Gonçalves Amanda , de Camargo Beatriz , Grundy Paul E. , Rosenberg Carla , Carraro Dirce M.
Published: June 2012

Wilms tumor (WT) is the most common kidney malignancy of childhood; nevertheless, its pathogenesis remains largely unknown. Although the majority of the WT occur sporadically, a strong genetic component is present at least in the many cases which are related to underlying syndromes. Tumor relapse occurs at a rate of approximately 15%, and molecular studies are focused in identifying markers to define the minimal therapy for limiting the late effects of treatment while maintaining high survival rate. Loss of heterozygosity of both 1p and 16q was already associated to an increased risk of relapse and death although detected in a very small subset of WT patients, making this feature a less sensitive prognostic factor. Somatic DNA copy number alterations (CNAs) are common genetic mutations in cancer, and often define key pathogenic events. This study was designed to assess the genome profile of CNAs in WT, aiming to identify genetic markers associated to relapse that could be of clinical and prognostic importance. We performed an array-CGH based survey of 48 WT samples, mainly tumors in stages III and IV, derived from patients with (17) and without (31) relapse in at least three years. Data was obtained using a high resolution oligoarray platform (180K - Agilent), with an average resolution >70 Kb, and analysis was performed on the software Nexus 6 (Biodiscovery). The analysis revealed high frequency of arm/whole chromosome alterations at 1q, 7q, and chromosomes 6 and 12 (gains), while losses were recurrent at 7p, 11 q, and 16q chromosome regions. WT derived from patients with relapse exhibited a distinctive pattern of genomic alterations, mainly characterized for an increased frequency of proximal 1q gain and low amplitude gain of chromosome 6. Additionally, analysis of small regions affected by recurrent focal alterations disclosed new genes that can be relevant for Wilms tumorigenesis and relapse.

Financial support: FAPESP/CNPq

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A53.
Abstract A57: The novel function of nuclear ErbB-2 in regulating transcription of rRNA genes
Authors: Li Long-Yuan , Chen Hsiuyi , Hsieh Yi-Hsien , Wang Ying-Nai , Chu Hsiao-Ju , Tsai Chang-Hai , Hung Mien-Chie
Published: June 2012

Accumulating evidence shows that deregulation of ribosomal RNA (rRNA) synthesis and translation control can facilitate tumorigenesis. The ErbB2 growth factor receptor is overexpressed in many human tumors and has been detected in the nucleus, but the role of nuclear ErbB2 is obscure. Here, we demonstrated a novel function of nuclear ErbB2 in enhancing rRNA gene transcription by RNA polymerase-l (RNA Pol I). Nuclear ErbB2 physically associates with β-actin and RNA Pol I, coinciding with active RNA Pol I transcription sites in nucleoli. RNAi-mediated knockdown of ErbB2 reduced pre-rRNA and protein synthesis. In contrast, wild-type ErbB2 augmented pre-rRNA level, protein production and cell size/cell growth, but not by an ErbB2 mutant which is defective in nuclear translocation. Chromatin immunoprecipitation assays revealed that ErbB2 enhances binding of RNA Pol I to rDNA. Additionally, ErbB2 associated with rDNA, RNA Pol I, and β-actin, suggesting how it could stimulate rRNA production, protein synthesis, and increased cell size and cell growth. Lastly, ErbB2-potentiated RNA Pol I transcription could be stimulated by ligand and was not substantially repressed by inhibition of PI3-K and MEK/ERK, the main ErbB2 effector signaling pathways. Together, our findings indicate that nuclear ErbB2 functions as a regulator of rRNA synthesis and cellular translation, which may contribute to tumor development and progression. This work was supported by National Health Research Institutes NHRI-EX100-9603BC, National Science Council NSC95-2311-B-039-002 and NSC99-3111-B-039-001 and Department of Health DOH99-TD-I-111-TM026 and DOH100-TD-C-111-005 (to LYL), Taiwan.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A57.
Abstract A63: TLR5 agonist CBLB502 protects mice from Fas-mediated liver damage without protecting tumors
Authors: Burdelya Lyudmila , Leonova Katerina , Kojouharov Bojidar , Veith Jean , Aygun-Sunar Semra , Gitlin Ilya , Allamaneni Shyam , Gleiberman Anatoli , Gudkov Andrei
Published: June 2012

We have previously shown the strong radioprotective properties of the Toll-like receptor 5 (TLR5) agonist flagellin and its derivative CBLB502 in both mouse and non-human primate models (Burdelya et al., 2008, Science 320: 226–230). Because no protection has been observed in any in vitro cell model regardless of the TLR5 status of the cells, we hypothesized that the radioprotective effects of the TLR5 agonist are indirect and mediated by factors produced by primary cells responding to flagellin in the organism. Using a combination of tools, including NF-kB-responsive reporter mice and immunohistochemical determination of tissues responding to CBLB502 by NF-kB activation, we defined liver hepatocytes as the primary pharmacological targets of flagellin. Surgical exclusion of the liver from the blood circulation completely abolished radioprotection of the bone marrow hematopoietic progenitor cells by CBLB502 suggesting that the liver acts as a mediator of at least some of the effects of the TLR5 agonist. Since the induction of NF-kB is known to activate multiple pro-survival mechanisms, we further hypothesized that administration of the TLR5 agonist can result in liver resistance to otherwise toxic conditions. Mice treated with Fas agonistic antibodies were employed as a model of acute hepatotoxicity. Injection of CBLB502 showed a strong preventive effect against Fas-mediated injury rescuing all of the injected mice in contrast to complete lethality in the control groups. The ability of CBLB502 to protect the liver was also demonstrated via reduced levels of liver enzymes in the peripheral blood and caspase activation in liver extracts of mice treated with Fas agonistic antibodies. Using two syngeneic tumor models, colon adenocarcinoma CT26 and lymphoma A20, growing as liver metastases in mice, we found that CBLB502 injections not only prevented liver damage, but also suppressed tumor appearance and growth when injected with or without anti-Fas antibodies. Thus, TLR5 agonist has potential to become a new agent for liver protection and suppression of liver metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A63.
Abstract B1: p53 isoforms, Δ133p53 and p53β, regulate aging-associated T lymphocyte senescence.
Authors: Mondal Abdul Matin , Horikawa Izumi , Pine Sharon R. , Fujita Kaori , Vojtesek Borivoj , Bourdon Jean-Christophe , Vera Elsa , Lane David P. , Blasco Maria A. , Harris Curtis C.
Published: June 2012

Normal human cells undergo finite divisions and reach a state of cellular senescence, which is a critical barrier for tumor progression in vivo and contributes to organismal aging. CD8+ T lymphocytes are an excellent model to study cellular senescence in vivo. The decreased proliferative potential and cellular senescence of CD8+ T lymphocytes are associated with loss of CD28 and gain of CD57 cell surface antigens, but the mechanisms regulating these phenotypic changes are unknown. The natural isoforms of human p53 protein, Δ133p53 and p53β, play important roles in regulating replicative cellular senescence in vitro (e.g., in normal human fibroblasts) and in vivo (e.g., in colon adenomas) and in different cell types (mesenchymal and epithelial origins). In this study we show that Δ133p53 and p53β are associated with and regulate replicative cellular senescence in CD8+ T lymphocytes (hematopoietic origin), which represent a physiological setting of in vivo cellular senescence. Loss of CD28 and gain of CD57 in CD8+ T lymphocytes were associated with increased donor age in normal individuals. When stimulated to proliferate in vitro, the FACS sorted CD28+/CD57− subsets of CD8+ T lymphocytes showed highest proliferation rate, whereas CD28−/CD57+ subsets showed lowest. The loss of proliferative potential of the CD28−/CD57+ cells was also associated with the shorter telomere length than the CD28+/CD57− subsets. Importantly, Δ133p53 and p53β expression levels were significantly changed during cellular senescence of CD8+ T lymphocytes, as observed in human fibroblasts and colon adenomas. Δ133p53 levels were decreased and p53β levels were increased in the senescent CD28−/CD57+ subset compared with the proliferative CD28+/CD57− subset. During in vitro culture, FACS sorted CD8+ T lymphocytes became senescent and lost Δ133p53 expression, which was associated with the loss of CD28 expression. Moreover, in overexpression experiments, p53β cooperated with full-length p53 to inhibit cellular proliferation, and Δ133p53 enhanced the proliferative potential of the CD8+ T lymphocytes, suggesting that the p53 isoforms regulate cellular proliferation and senescence in CD8+ T lymphocytes. Our study provides insight toward understanding the mechanisms regulating physiological aging of normal human circulating T lymphocytes and thus proposes a novel approach for reinstating replicative potential and immune function of the senescent CD8+ T lymphocytes.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B1.
Abstract B15: The homeobox patterning gene DLX4 confers resistance to transforming growth factor-β signaling in tumors
Authors: Trinh Bon Q. , Barengo Nicolas , Naora Honami
Published: June 2012

Rationale: Transforming growth factor-β (TGF-β) inhibits cell proliferation and also induces epithelial-to-mesenchymal transition (EMT). The antiproliferative effect of TGF-β is orchestrated by a cytostatic program of gene responses that induce G1 arrest and are controlled by Smad-dependent mechanisms, whereas TGF-β induces EMT by both Smad and non-Smad mechanisms. In contrast to normal cells, many tumors are resistant to the antiproliferative effect of TGF-β. This resistance has been attributed to TGF-β receptor or Smad mutations in several types of tumors, particularly those of gastrointestinal origin. However, the rareness of these mutations in many other tumors (e.g., prostate, lung cancers) indicates that resistance to TGF-β also stems from other aberrations. The transcription factor encoded by the homeobox gene DLX4 is aberrantly expressed in a wide range of malignancies. Increasing evidence indicates that crosstalk between members of the TGF super-family and DLX genes is important for controlling normal embryonic patterning. The objective of this study is to determine whether and how DLX4 modulates the TGF-β signaling pathway in tumors.

Experimental procedure: The effect of DLX4 on TGF-β-mediated growth inhibition and EMT was investigated by cell cycle and morphological analyses in different types of nontumorigenic and malignant epithelial cells. Molecular mechanisms of DLX4 in modulating TGF-β signaling were determined by protein and chromatin immunoprecipitation and analysis of transcriptional activity of TGF-β target genes.

Results: Our studies demonstrate that DLX4 blocks the antiproliferative effect of TGF-β by disabling key transcriptional control mechanisms of the TGF-β cytostatic program. In particular, DLX4 blocked the ability of TGF-β to induce p15Ink4B and p21WAF1/Cip1 transcription by directly interacting with Smad4 and Sp1. Binding of DLX4 to Smad4 prevented Smad4 from forming transcriptional complexes with Smad2 and Smad3, whereas binding of DLX4 to Sp1 inhibited DNA-binding activity of Sp1. DLX4 also induced expression of c-myc, a repressor of p15Ink4B and p21WAF1/Cip1 transcription. On the other hand, DLX4 enabled epithelial cells to retain epithelial morphology and partially prevented TGF-β-mediated downregulation of E-cadherin and induction of N-cadherin.

Conclusion: Our studies demonstrate that DLX4 blocks the antiproliferative effect of TGF-β and partially inhibits TGF-β-mediated EMT. The ability of DLX4 to counteract key transcriptional control mechanisms of the TGF-β cytostatic program could explain in part the resistance of tumors to the anti-proliferative effect of TGF-β in the absence of mutations in core components of the TGF-β signaling pathway.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B15.
Abstract B32: Telomerase activity confers growth and DNA damage survival advantages in telomerase-negative transformed human cells
Authors: Fleisig Helen B. , Wong Judy M.Y.
Published: June 2012

Constitutively high telomerase activity is detected in more than 85% of human cancers. Together with the activation of oncogenic growth through RAS-oncogene-associated signal transduction pathways and the inactivation of tumor suppressor pathways regulated by p53 and Rb, telomerase reverse transcriptase expression promotes tumorigenic transformation of human cells. The prevalence of telomerase, rather than a homologous recombination-based mechanism, for telomere length maintenance in human cancers, suggests that telomerase has auxiliary roles in tumorigenesis. Here, we investigate growth advantages provided by the telomerase enzyme in oncogene-transformed human cells that do not require telomerase activity for telomere length control. We employed retroviral vector directed expression of telomerase components in human cell models that utilize the alternate lengthening of telomeres (ALT) mechanism for telomere maintenance. Forced expression of telomerase in ALT cells did not abolish the ALT mechanism, and ALT molecular characteristics were maintained in the resultant cell lines. Our data indicates that in these oncogene-transformed ALT cells, telomerase activity accelerates cell growth kinetics and promotes anchorage-independent growth. Co-culture experiments demonstrated that this growth advantage conferred by telomerase activity is not transferable by cytokine exchange and not likely the result of increased cellular crosstalk. Growth advantages provided by telomerase required all functional aspects of the enzyme. Dissociation-of-activities telomerase mutants and other functionally defective versions of telomerase were unable to promote oncogene-transformed cell growth, implying that canonical telomerase activities may be involved. Telomerase-positive ALT cells pass through the cell division phases of the cell cycle with increased kinetics, suggesting that the observed cell growth advantage is cumulative over cycles of proliferation. In addition, telomerase-positive ALT cells displayed an increased tolerance to the cytotoxic effects of DNA damaging agents that cause double-stranded DNA breaks. We conclude that telomerase expression provides growth and survival advantages to oncogene-transformed human cells; this supports the development of telomerase-based anticancer chemotherapies targeting these growth-promoting effects.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B32.
Abstract B47: Exploring the mechanism of cancer stem cell-specific action by salinomycin in yeast as a model
Authors: Siede Wolfram
Published: June 2012

The antibiotic salinomycin represents a selective potassium ionophore. It has recently attracted considerable attention due to its stem-cell specific mode of action as elucidated in a breast cancer stem cell model [1]. Further studies revealed additional benefits, e.g. the triggering of apoptosis in resistant cancer cell lines and reversal of multidrug resistance [2,3]. In budding yeast, we discovered that this agent is active and, similar to nigericin, prominently causes mitochondrial damage as revealed by the emergence of respiration-defective cells. We also noted the frequent occurrence of salinomycin-resistant clones which may prove to be an obstacle in chemotherapy. We used the collection of systematic gene deletions in haploid yeast to characterize genes whose deletion confers sensitivity or resistance to salinomycin if a carbon source is provided (glycerol) that requires active respiration for growth. With this toxicogenomics approach in a model organism, we attempt to elucidate cancer stem cell-specific therapy targets and suggest strategies to avoid the development of salinomycin resistance.

Among salinomycin-sensitive deletion mutants, significant overlap was found with known mutants sensitive to the ionophore monensin. Within this group, mutants that compromise vacuole/Golgi function and autophagy dominate. Novel genes were also uncovered which confer salinomycin sensitivity if deleted, such as CAJ1, encoding a heat shock protein of the dnaJ family, and certain arginine synthesis genes.

On the other hand, deletions of TOR pathway components as well as deletions of the E2-ubiquitin conjugating enzymes UBC13 and MMS2 were among the most salinomycin-resistant mutants we found.

In almost all cases, a strong correlation between salinomycin and nigericin sensitivity was observed. Since salinomycin appears to be the more efficient anti-cancer stem cell agent [1], the few cases of differential sensitivity will be discussed.

[1] Gupta PB, Onder TT, Jiang G, Tao K, Kuperwasser C, et al. (2009) Cell 138:645–659. [2] Fuchs D, Heinold A, Opelz G, Daniel V, Naujokat C (2009) Biochem Biophys Res Commun 390:743–749. [3]Fuchs D, Daniel V, Sadeghi M, Opelz G, Naujokat C (2010) Biochem Biophys Res Commun 394:1098–1104.

Supported by Cancer Prevention and Research Institute of Texas.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B47.
Abstract B63: Identification of small molecules that selectively target glioma stemlike cells
Authors: Lim S. Kyun , Wei Shuguang , Samples Darren , Li Yanjiao , Cho Woosung , McKay Renee , Williams Noelle S. , Posner Bruce A. , Parada Luis F.
Published: June 2012

Gliomas are the most frequently occurring primary malignancies in the central nervous system, with glioblastoma multiforme (GBM) the most common and most aggressive of these tumors. GBM is virtually incurable because, following the standard treatment of care—surgical resection, radiation, and chemotherapy—the tumors eventually recur. Recent studies including our own indicate a crucial role for a specific subset of tumor cells (cancer stem cells) in tumor development and recurrence. We have generated fully penetrant, tumor-suppressor-based somatic mouse models of glioma, with gene mutations frequently found in human glioma (p53, NF1, Pten; termed Mut6 tumors). These tumor models develop GBM that histopathologically and molecularly mimics the human disease. Transcriptional profiling of these tumors revealed that they are most similar to human GBM. Using the pooled Mut6 stem-like cancer cells we performed a high-throughput screen designed to identify small molecules that inhibit the growth of these cells, as measured by a luminescence ATP assay. We performed a 200,000 compound library screen, initially identifying 4,480 compounds that were then retested in increasingly stringent assays such that we now have approximately 70 unique compounds that adversely affect glioma stem cell growth. These compound hits were found to have EC50s in the nanomolar range and to act with considerable specificity, affecting the mutant stem cells at concentrations that do not affect cultured astrocytes or mouse embryonic fibroblasts. Among these, we tested 46 compounds in metabolic stability tests and found 17 compounds with excellent stablilty profiles. We believe these compounds present promising lead compounds for drug development as well as for uncovering critical pathways in glioma tumor development and self renewal.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B63.
Abstract C12: Identification of potential protein targets of isothiocyanates by proteomics
Authors: Mi Lixin , Hood Brian L. , Stewart Nicolas A. , Xiao Zhen , Govind Sudha , Wang Xiantao , Conrads Thomas P. , Veenstra Timothy D. , Chung Fung-Lung
Published: June 2012

Isothiocyanates (ITCs), such as phenethyl isothiocyanate (PEITC) and sulforaphane (SFN), are effective cancer chemopreventive compounds. Induction of cell cycle arrest and apoptosis is believed to be a major mechanism for their cancer preventive activity. Our previous studies indicate that covalent binding to target proteins is an important upstream event. However, the identity of ITC binding targets remains largely unknown. To identify proteins that are covalently modified by ITCs, human non-small cell lung cancer A549 cells were treated with 14C-PEITC and 14C-SFN and the cell lysates were extracted for analysis by 2-D gel electrophoresis and mass spectrometry. After superimposing the colloidal Coomassie blue protein staining pattern with the pattern of radioactivity obtained from X-ray films, it was clear that only a small fraction of cellular proteins contained radioactivity, presumably resulting from selective binding with PEITC or SFN via thiocarbamation. In this study, more than 30 proteins with a variety of biological functions, including cytoskeleton, redox regulation, protein quality control, stress response, mitochondria, and signaling transduction, were identified with high confidence. Here we report the identities of these potential ITC target proteins and discuss their biological relevance. The discovery of the protein targets may facilitate studies of the mechanisms by which ITCs exert their cancer preventive activity and provide molecular basis for designing more efficacious ITC compounds.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C12.