bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 130: Regulatory role of miR-29b in prostate cancer metastasis
Authors: Ray Ratna B. , Ru Peng , Steele Robert , Newhall Philip , Toth Karoly
Published: August 2012

Prostate cancer remains the second leading cause of cancer deaths among American men. Earlier diagnosis increases survival rate in patients. However, treatments for advanced disease are limited to hormone ablation techniques and palliative care. Thus, new methods of treatment are necessary for inhibiting progression of the disease. We have shown previously that microRNA-29b (miR-29b) expression was lower in prostate cancer cells as compared to prostate epithelial cells. Among the prostate cancer cell lines, metastatic prostate cancer cells displayed lowest expression of miR-29b. In this study, we have observed that PC-3M cells that constitutively overexpressed miR-29b failed to colonize the lungs and other organs of SCID mice after intravenous injection, while PC-3M cells expressing a control miRNA formed multiple nodules in the lung. PC-3M cells expressing miR-29b inhibited wound healing and invasiveness of cancer cells. Epithelial cell marker E-cadherin expression was enhanced in prostate cancer cells expressing miR-29b as compared to control cells. On the other hand, N-Cadherin and Snail1 expression were downregulated in PC-3M cells expressing miR-29b. Together these results suggested that miR-29b is an anti-metastatic miRNA in prostate cancer that acts at multiple steps of the metastatic cascade. Therefore, miR-29b could be a potentially new attractive target for therapeutic intervention in prostate 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 130. doi:1538-7445.AM2012-130
Abstract 1431: A novel tumor-suppressor role of MyoD, a muscle differentiation factor, in mouse models of medulloblastoma
Authors: Dey Joyoti , Tapscott Stephen J. , Olson James M.
Published: August 2012

Medulloblastoma, an embryonal tumor of the cerebellum, is the most common pediatric brain cancer. For decades, it has been known that a small subset of medulloblastomas present with myogenic differentiation. However, the mechanistic basis and significance of this biological anomaly remain to be determined. We have identified hitherto unknown expression of muscle differentiation factor, MyoD in cerebellar tumors from mouse models of medulloblastoma as well as in a subset of human medulloblastomas. At a cellular level, MyoD is expressed in mitotically active cells and intriguingly, in mouse tumors does not activate its canonical targets involved in the muscle differentiation program. To understand the functional consequence of this finding in medulloblastoma genesis, we have conducted genetic studies to assess tumor formation in the SmoA1 and SmoA2 medulloblastoma models, on a MyoD-deficient background. We demonstrate that MyoD acts as a haploinsufficient tumor suppressor as the MyoD wt/-; SmoA1 and MyoD wt/-; SmoA2 mice have an accelerated onset of tumors compared to MyoD wt/wt; SmoA1 or MyoD wt/wt; SmoA2 mice respectively. Our findings suggest that the expression of MyoD might be an oncogene-induced compensatory response in the cerebellum to suppress tumor growth by restoring balance between proliferation and differentiation, similar to the role of some other bHLH transcription factors. Harnessing this latent tumor suppressor network to induce differentiation or cell cycle arrest holds promise for future therapeutic interventions.

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 1431. doi:1538-7445.AM2012-1431
Abstract 1433: TC21/R-Ras2 is a critical mediator of the Nf1 oncogenic switch
Authors: Patmore Deanna M. , Welch Sara , Fulkerson Patricia , Wu Jianqiang , Choi Kwangmin , Eaves David , Kordich Jennifer , Collins Margaret H. , Cripe Timothy P. , Ratner Nancy
Published: August 2012

The TC21/R-Ras2 protein is an oncogenic member of the Ras family. Ras proteins act as binary switches which are ‘active’ when bound to GTP and ‘inactive’ when bound to GDP. GTPase activating proteins (GAPs) accelerate the hydrolysis from Ras-GTP to Ras-GDP. This Ras-related GTPase TC21 has transforming capabilities similar to H, N and K-Ras. Activated alleles of TC21 transform epithelial and fibroblast cell lines and induce tumors in vivo. To explore the role of TC21 in cancer we used a model of Ras activation driven by loss of the NF1 tumor suppressor protein, a GAP for all Ras proteins including TC21. Thus loss of NF1 predicts increased levels of activated TC21/R-Ras2. NF1 loss in Schwann cells of the peripheral nervous system causes benign tumors known as neurofibromas. Neurofibromas can transform to sarcomas known as malignant peripheral nerve sheath tumors (MPNSTs). We found that TC21 loss delayed benign neurofibroma formation in Nf1fl/fl;DhhCre mice. Nf1 loss increased mRNA encoding the cytokine transforming growth factor-beta (TGF-β) and rendered Schwann cell progenitors insensitive to TGF-β; these phenotypes could be rescued by the Ras-related protein TC21/R-Ras2 and were mediated through TGF-β receptors. Conversely, growth of Nf1;Trp53 brain tumors and NF1−/− MPNST sarcomas were accelerated by TC21 loss. MPNST from Nf1;Trp53 mice and NF1−/− MPNST xenografts had increased levels of mRNA encoding TGF- ≤ ligands, and blocking TGF- ≤ decreased sarcoma size induced by shTC21. In benign and malignant tumors an AKT-dependent pathway regulated TGF- ≤ expression. Indicating relevance to human tumorigenesis, global gene expression analyses demonstrated increases in expression of TGF- ≤ ligands and decreases in TGF- ≤ receptors in human neurofibromas and MPNSTs. Thus, we identify critical roles for TC21 in regulation of TGF- ≤ expression. The results are important because TGF- ≤ acts as a tumor suppressor in numerous types of benign tumors and is also known for its oncogenic role in cellular transformation and tumor progression. While it has been known that Ras proteins are involved in TGF- ≤ mediated tumor suppression and oncogenesis, integration between the pathways is incompletely understood, especially in vivo. The study demonstrates that TC21 can be a major regulator of the duality of TGF- ≤ effects on tumorigenesis in vivo. This work was supported by a grant to NR (NIH P50NS057531-03).

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 1433. doi:1538-7445.AM2012-1433
Abstract 1438: Strong expression of CD57 is associated with aggressive neuroblastoma cells in vitro and in vivo, and with undifferentiated neuroblastoma cells in situ
Authors: Schlitter Anne-Marie , Dorneburg Carmen , Barth Thomas F.E. , Wahl Joachim , Schulte Johannes H. , Brüderlein Silke , Debatin Klaus-Michael , Beltinger Christian
Published: August 2012

Neuroblastoma is thought to originate from neural crest-derived cells. CD57 defines migratory neural crest cells in normal development and is expressed in neuroblastomas. We therefore investigated the role of CD57 expression in neuroblastoma cells in vitro, in vivo and in situ. Compared to CD57low neuroblastoma cells, CD57high cells developed tumors with decreased latency after orthotopic transplantation into adrenal glands of immunodeficient mice. In addition, CD57high neuroblastoma cells were also more clonogenic, induced more spheres, were less lineage-restricted and showed enhanced invasiveness. After tail vein injection more CD57high cells homed to liver and lung and formed metastases than CD57low cells. In stroma-poor neuroblastoma of patients CD57high cells were associated with undifferentiated tumor cells across all stages and tended to be more frequent after chemotherapy. We thus conclude that strong expression of CD57 is associated with some aggressive attributes of neuroblastoma cells and is linked with undifferentiated neuroblastoma cells in patients.

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 1438. doi:1538-7445.AM2012-1438
Abstract 144: MicroRNA-190, regulated by estrogen receptor signaling, suppresses expression of the metastasis-promoting gene PAR-1 and is associated with breast cancer progression
Authors: Chu Hou-Wei , Cheng Chun-Wen , Chou Wen-Cheng , Hu Ling-Yueh , Wang Hsiao-Wei , Hsiung Chia-Ni , Wu Pei-Ei , Hsu Huan-Ming , Yu Jyh-Cherng , Shen Chen-Yang
Published: August 2012

Cancer metastasis contributes to mortality of breast cancer patients. The present study, based on the fundamental concept that dissociation of the extracellular matrix is the driving force for tumor metastasis, was performed to examine the hypothesis that microRNA-190 (miR-190) is important in regulating breast cancer metastasis by decreasing the expression of protease-activated receptor-1 (PAR-1), a gene encoding a receptor for matrix metalloproteinase1 and thrombin that is associated with tumor metastasis. This hypothesis was initially suggested by the observations that the expression of a reporter gene could be regulated by a specific sequence in the 3′-untranslated region of PAR-1 and that miR-190 was complementary to this sequence. Support for our hypothesis came from the findings that (a) PAR-1 expression was directly inhibited by miR-190, (b) increased miR-190 expression suppressed cell migration and invasiveness, and (c) the level of miR-190 expression in primary breast carcinomas correlated with overall survival. Interestingly, we defined the promoter region of miR-190 and noted that it contained half of an estrogen receptor (ER) response element, supporting the breast tumorigenic contribution of miR-190. This was further confirmed by the findings that miR-190 expression was activated by 17β-estradiol and that the ER bound directly to this promoter and regulated miR-190 expression. The findings of the present study may explain why ER-positive patients usually have a favorable progression and how ER regulates cancer metastasis, i.e. ER signaling regulates miR-190 expression, thus causing suppression of PAR-1 expression, resulting in inhibition of breast cancer metastasis.

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 144. doi:1538-7445.AM2012-144
Abstract 1440: Validation of potential therapeutic targeting of IL-6/JAK/STAT3 pathway by AZD1480 in neuroblastoma and other pediatric tumors
Authors: Yan Shuang , Thiele Carol J
Published: August 2012

Neuroblastoma is the most deadly extra-cranial solid childhood tumor. Despite advanced therapies, over 60% of high-risk NB patients have aggressive tumors spreading to bone and bone marrow and die of metastasis-related disease. IL-6 promotes the growth and survival of metastatic NB cells via activation of STAT3 in the BM and is an independent poor-prognosis marker in tumors from high-risk NB patients. This suggests that blockade of IL6/JAK/STAT3 signaling may represent a promising therapeutic strategy. We tested the anti-tumor effect of inhibition IL6/JAK/STAT3 pathway by the JAK1/2 inhibitor AZD1480, which is in Phase II clinical trials in adult tumors, in three highly metastatic pediatric tumor types (Neuroblastoma, Ewing sarcoma and rhabdomyosarcoma). AZD1480 (0.5uM) significantly blocked IL-6-induced P-STAT3-Tyr705 in all tumor types tested. AZD1480 decreased cell viability in the 6 NB, 5 RMS and 2 EWS cell lines tested (median IC50 1.17uM, ranging from 0.42-5.1uM). AZD1480 induced cell growth inhibition, G2 arrest and apoptosis in vitro. Moreover, AZD1480 inhibited the expression of identified direct STAT3 targets such as cell cycle regulators CyclinD2, CyclinD3 and CDC25A, antiapoptotic proteins Bcl-2 and Survivin, metastasis-related protein TIMP-1 and c-myc consistent with its repression of cell growth, induction of G2 arrest and apoptosis. In in vivo Neuroblastoma xenograft models, AZD1480 suppressed growth of SY5Y and KCNR xenografts and increased survival of mice bearing KCNR xenografts (P=0.0001) and SY5Y xenografts (P=0.02). Altogether, these data suggest the clinical blockade of IL6/JAK/STAT3 signaling by AZD1480 may represent a promising new therapy in NB and other pediatric tumors. We thank Dennis Huszar and AstraZeneca for the AZD1480 and helpful discussions. Key words: neuroblastoma, JAK2, STAT3, IL-6, targeted 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 1440. doi:1538-7445.AM2012-1440
Abstract 1450: Targeting the ATM kinase as a novel strategy for radiosensitizing glioblastoma multiforme in mice
Authors: Biddlestone-Thorpe Laura , Muhammad Sajjad , Rosenberg Elizabeth , Golding Sarah E. , Adams Bret R. , Tokarz Mary , Khalil Ashraf , Gilfor Donna , O'Connor Mark , Valerie Kristoffer
Published: August 2012

Glioblastoma multiforme (GBM) is the most lethal type of brain cancer. At best, mean survival is only 12-15 months so an improvement of current therapy is long overdue. Current treatment includes surgery and chemoradiation. The short survival of GBM patients is due, in part, to the innate radioresistance and vicious invasiveness of GBM. ATM, ataxia telangiectasia (A-T) mutated, would be an excellent target for radiosensitizing GBM because of its critical role in regulating the DNA damage response (DDR) and other cellular processes. As a first step towards this goal, we tested the ability of the novel ATM kinase inhibitor KU-60019 to radiosensitize GBM in mice. Using an orthotopic xenograft model of GBM, nude mice were implanted with human glioma cells expressing reporter genes for monitoring tumor growth and spread. KU-60019 was administered intra-cranially by convection-enhanced delivery or by osmotic pump. Imaging, survival, and signs of inhibiting the DDR using immunohistochemistry were used to characterize the effects of KU-60019 on tumor and normal brain. Our results show that compared with untreated, KU-60019 alone, or radiation alone treated mice, the combined effect of KU-60019 and radiation significantly increased survival at least 2-fold and sometimes even cured the animals. Multiple glioma cell lines with varied genetic backgrounds are currently being tested. Altogether, our results show that KU-60019 is able to overcome GBM radioresistance, a major obstacle in the treatment of GBM, and significantly prolong the survival of animals. Thus, an ATM kinase inhibitor may have great potential as adjuvant therapy in the clinic.

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 1450. doi:1538-7445.AM2012-1450
Abstract 1452: mTOR inhibition radiosensitizes bladder cancer tumor cells in vitro and in vivo: A novel strategy for treatment
Authors: Nassim Roland , Mansure Jose , Chevalier Simone , Cury Fabio , Parker William , Davis Stephen , Cury Joice , Kassouf Wassiim
Published: August 2012

Background: Radiation therapy for invasive bladder cancer allows for organ preservation but systemic toxicity and local control remain problematic. As such, there is a need to increase radiosensitization of tumor cells to improve efficacy. The aim of this study was to investigate if mTOR (mammalian target of rapamycin), a downstream kinase of the PI3K/Akt survival pathway, may be a target for combined bladder cancer therapy. Methods: Clonogenic assays were performed using 6 bladder cancer cell lines in order to address the effects of ionizing radiation (IR) on growth, when tested alone and in combination with RAD001, a potent mTOR inhibitor. Cell cycle analysis was performed using flow cytometry. In the in vivo study, nude mice were subcutaneously injected with KU7 and 253J-BV cells. Treatment with RAD001 (1.5 mg/kg, daily), fractionated IR (total 9 Gy), and the combination of RAD001 and IR was followed over 4 weeks. Tumor growth kinetics was measured and tumor weight at the experimental endpoint. Results: In vitro, a significant decrease in colony formation was observed in the combined treatment when compared to RAD001 or radiation alone (p<0.05) in all cell lines. A G0/G1 as well as a significant increase in G2 arrest was observed in the combined treatment compared to either treatment alone. Changes in the levels of Cyclin D1, p27 and p21 correlated with the observed changes in the cell cycle. Moreover, IR rapidly activated AKT whereas RAD001 effectively inhibited the mTOR downstream signaling as shown by the inhibition of the phosphorylation of S6. Furthermore, autophagy was induced following the treatment with RAD001 and in combination as indicated by the conversion of LC3-I to LC3-II, a protein marker for autophagy. Our in vivo data confirmed our in vitro data, wherein a significant decrease in tumor weight was observed in the combined treatment arm (90% decrease, p<0.001) compared to either treatment alone (60% decrease for RAD001, p<0.05; 77% decrease for IR, p<0.05). These findings point to additive and possibly synergistic beneficial effects of the combined on bladder cancer. Conclusions: The inhibition of mTOR signaling appears promising as a therapeutic modality for bladder cancer, especially in the context of combination with radiation 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 1452. doi:1538-7445.AM2012-1452
Abstract 1463: PARP inhibition reverses radiation resistance conferred by ETS fusions in prostate cancer
Authors: Han Sumin , Brenner Chad , Sabolch Aaron , Wilder-Romans Kari , Knudsen Karen , Lawrence Theodore , Chinnaiyan Arul , Feng Felix
Published: August 2012

Background: ETS gene fusions, which are found in approximately half of all prostate cancers, result in overexpression of ETS transcription factors, of which ERG is the prototype. We previously discovered that ERG interacts with the DNA damage response protein poly (ADP-ribose) polymerase 1 (PARP1). Therefore, we hypothesized that the ERG-PARP1 interaction may confer radiation resistance by increasing DNA repair efficiency, and this radioresistance can be reversed with PARP1 inhibition. Methods: We used lentiviral approaches to establish isogenic models of ERG overexpression in PC3 and DU145 prostate cancer cell lines. We then assessed the role of ERG overexpression on 1) PARP1 activity (via immunoblots for poly ADP-ribose (PAR) formation), 2) DNA repair (via COMET assays and immunofluorescent microscopy for gamma-H2aX foci), and 3) clonogenic survival, before and following radiation +/− the PARP1 inhibitor olaparib. We also created ERG mutants with a point mutation (Y373) which disrupted the ERG-PARP interaction, and assessed the role of this interaction on radiation response. Finally, we established xenografts from ERG-overexpressing and control PC3 cells, and treated these xenografts with radiation +/− PARP1 inhibition. Results: In both PC3 and DU145 cells, ERG overexpression resulted in increased PARP1 activity and quicker repair of DNA damage, both of which were reversed with olaparib. ERG overexpression resulted in a 1.3 fold increase in clonogenic survival following radiation, consistent with radioresistance. PARP1 inhibition with olaparib preferentially radiosensitized ERG-positive cells, by a factor of 1.5 relative to ERG-negative cells (p<0.05). Additionally, disruption of ERG-PARP interaction via point mutation reversed the ERG-mediated increase in clonogenic survival following radiation. Within PC3 xenografts, ERG overexpression also conferred radioresistance which was reversed with PARP1 inhibition. Conclusions: In these prostate cancer cell models, ERG overexpression confers radiation resistance via increased efficiency of DNA repair following radiation. This radioresistance is dependent on the ERG-PARP1 interaction, and can be reversed via inhibition of PARP1 both in vitro and in vivo. These novel findings motivate the use of PARP1 inhibitors as radiosensitizers in patients with localized ETS fusion-positive prostate cancers.

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 1463. doi:1538-7445.AM2012-1463
Abstract 1471: Role of ferritin heavy chain in therapeutic sensitivity of human glioblastoma cells
Authors: Pang Min , Liu Xiaoli , Madhankumar A. B. , Connor James
Published: August 2012

Elevated iron requirements and heightened iron metabolism is key to the survival and proliferation of cancer cells. As one of the major iron regulatory proteins, ferritin is elevated in cancer cells and we have previously shown that decreasing ferritin expression in human glioblastoma cells will increase the sensitivity to BCNU and radiation both in vitro and in vivo. In this study, we investigate the underlying mechanism of this finding. Through a nanotechnology-based transfection platform, the human glioma cell line U251 was transfected with H-ferritin siRNA and an effective knockdown efficiency of protein was achieved within 48 hours. H-ferritin down-regulation in glioma cells was associated with a transient decrease in transferrin receptor, suggesting a release of intracellular iron with loss of ferritin. This iron release in turn generated intracellular oxidative stress, which was demonstrated by protein oxidation. The stability of hypoxia-inducible factors (HIFs), which is an indicator of radioresistance, was decreased in glioma cells with H-ferritin down-regulation. This observation is consistent with the increased sensitivity to treatment. Exposure to radiation resulted in increased protein oxidation which could be exacerbated by H-ferritin down-regulation. Thus there is a synergistic effect of radiation and H-ferritin down-regulation; possibly also including the destabilization of HIFs. Additionally, we have previously demonstrated a DNA protection role for H-ferritin. Down-regulation of H-ferritin is associated with increased DNA vulnerability when cells were exposed to ionizing radiation. Moreover, the activation of DNA repair mechanisms was impaired when H-ferritin was absent. Finally, we expanded the vulnerability studies to include the first-line chemotherapeutic agent temozolomide and found that H-ferritin down-regulation increased the sensitivity of glioma cells to this DNA alkylating agent. This study suggests that the iron management protein, H-ferritin, has a cytoprotective role in human glioma cells, which renders them more resistant to conventional therapies. Therefore down-regulation of H-ferritin via nanoliposomes delivering siRNA is a potential adjuvant therapy in glioma 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 1471. doi:1538-7445.AM2012-1471
Abstract 1494: Intrinsic and extrinsic TME factors modulate breast cancer progression
Authors: George Andrea L. , Rajoria Shilpi , Suriano Robert , Mittelman Abraham , Tiwari Raj K.
Published: August 2012

The tumor microenvironment (TME) of breast cancer is a heterogeneous population of tumor cells, infiltrating endothelial cells, immunomodulatory cells, and underlying stroma. This cellular cross-talk is key to tumor progression; however the signaling pathways involved remain unclear. Rapid expansion of breast cancer cells requires sufficient supply of oxygenated blood supported by tumor induced neovasculature. Our previous studies demonstrated that estrogen mediates neovascularization via recruitment of bone marrow derived endothelial progenitor cells (BM-EPCs). However, hypoxia, a major cellular characteristic of cancer cell growth, mimics estrogen induced vascularization as evidenced by HIF-1α translocation and secretion of vascular endothelial growth factor (VEGF). These studies were carried out in the TG1-1 murine mammary cancer cell line and used as a model. Conditioned media from TG1-1 cells enhanced endothelial cell migration and tube formation in vitro. Treatment of tumor cells with the anti-estrogen Fulvestrant as well as the HIF-1 inhibitor YC-1 abrogated the effects of estrogen. Further, use of the PI3K inhibitor wortmannin as well as the protein inhibitor cyclohexamide, elucidated the necessity of a functional AKT signaling pathway in this estrogen induced neovasculogenesis. While the cell-cell interaction studies demonstrate a considerable modulation of the tumor microenvironment, the co-culture experiments using immunomodulatory cells and epithelial cells induced epithelial to mesenchymal transition (EMT) in TG1-1 cells. We demonstrated that the murine macrophage cell line RAW264.7 secretes factors that modulate tumor cell EMT via upregulation of TWIST and Slug and an increase in tumor cell migration and invasion. To elucidate the modulatory secreted factors, we performed western blot analysis of the TGF-β signaling pathway and observed differences in SMAD levels. However, neutralizing antibody studies indicate that TGF-β is not the sole modulator of RAW264.7 induced EMT in Tg1-1 cells. Taken together, cytokines as extrinisic factors and tumor hypoxic conditions generating intrinsic factors, act in concert to alter breast cancer progression. Our data demonstrate a need to target multiple TME interacting pathways as a future breast cancer treatment strategy.

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 1494. doi:1538-7445.AM2012-1494
Abstract 1496: Changes in white adipose tissue progenitor populations with ovarian cancer
Authors: Shea Amanda A. , Cohen Courtney A. , Roberts Paul C. , Schmelz Eva M.
Published: August 2012

Ovarian cancer is the fourth leading cause of cancer death in women and has the highest mortality rate of all gynecological malignancies. Among the greatest risk factors are age, reproductive history, hormone therapy, and more recently suggested, obesity. Currently, the mechanism for how obesity contributes to ovarian cancer is unknown, but there is potential for adipose tissue-associated cells to be key players in this pathogenesis. The stromal vascular fraction (SVF) of white adipose tissue is a rich source of various stem and progenitor cell populations, which can be recruited by cancer cells to enhance cancer progression and metastatic potential. Studies have shown that there is an increase in progenitor populations within the adipose tissue with obesity and age, two risk factors for ovarian cancer. While it has been shown that SVF cells can contribute to cancer, it has not been determined what impact cancer progression has on adipose tissue. It is plausible that ovarian cancer has systemic effects, which may influence cell populations within adipose tissue to promote metastases. Our lab has developed a spontaneously transformed murine ovarian surface epithelial (MOSE) cell model that becomes increasingly more aggressive with repeated passaging. Late passage cells rapidly form tumors when injected into mice, while earlier passage cells do not. Using this model, we investigated the effects of ovarian cancer on systemic changes in progenitor populations. Firefly luciferase-expressing MOSE-L TICv cells, a highly aggressive, metastatic tumor-initiating cell variant were injected into the peritoneal cavity of C57BL/6 mice and stem/progenitor populations and various immune cell populations within the perigonadal white adipose tissue, blood, ascites, and omentum were immunophenotyped by flow cytometry. Changes in gene expression profiles were also analyzed using quantitative real-time PCR. Interestingly, peritoneal dissemination changed the profile and composition of progenitor populations in the various tissues, suggesting that ovarian cancer does have a more widespread impact, affecting the blood and perigonadal adipose tissue. Additionally, co-culture studies demonstrate that MOSE cells and SVF associated cells positively interact enhancing tumor spheroid growth and provide survival signals. This suggests a synergistic relationship between the MOSE and SVF cells. These discoveries may provide a mechanistic link for the detrimental impact of obesity on ovarian cancer progression.

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 1496. doi:1538-7445.AM2012-1496
Abstract 1525: Regulation of bone marrow angiogenesis by CXCL12 in the leukemia tumor microenvironment
Authors: Gibson Laura F. , Piktel Debra , Diamond Julie , Cavendish John , Gencheva Marieta , Wysolmerski Robert
Published: August 2012

While it is well established that angiogenesis is essential for the progression of solid tumors, its role in hematological tumors is more recently becoming fully appreciated. In the current study we have investigated the potential role of leukemic cells in regulating local angiogenesis as well as the modulation of tumor cell CXCL12 expression subsequent to interaction with bone marrow derived osteoblasts as one mechanism by which local vascular rich niches may be created. Human REH acute lymphoblastic leukemia (ALL; ATCC #CRL-8286) increased vessel density when placed on the chorioallantoic membrane (CAM) assay. Conditioned media from these same tumor cells increased human brain microvessel endothelial cell (HBMEC) motility and tube formation suggesting leukemia cell influence on surrounding vasculature. Strikingly, while REH cells express negligible CXCL12 at baseline, the chemokine is consistently induced to easily detectable levels upon co-culture with human osteoblasts indicating one mechanism by which tumor cells within the bone marrow microenvironment may be poised to enhance vascular cell recruitment even more robustly than leukemic cells alone. Preliminary evaluation of primary, patient-derived ALL leukophoresis samples demonstrated a comparable increase in tumor cell CXCL12 indicating this modulation is not limited to an established tumor cell line. Increased expression of CXCL12 by REH leukemic cells was consistent with enhanced chemotaxis of HUVECs toward the co-culture of tumor and osteoblasts when compared to either cell type alone. The inclusion of 5-Aza-deoxycytidine (Aza-C) to REH cells alone resulted in expression of CXCL12 in the absence of osteoblast co-culture, suggesting methylation may play a regulatory role in the suppression of this chemokine. As a site in which metastatic disease is often refractory to standard therapy, in addition to the anatomical niche in which hematopoietic malignancies initiate and most frequently relapse, regulation of local angiogenesis in the bone marrow microenvironment requires further investigation. Our preliminary observations suggest CXCL12 may play an important role in regulating leukemic cell niche angiogenesis, and targeting it could potentially represent a novel application of antagonists currently in clinical trials in an effort to treat refractory leukemia.

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 1525. doi:1538-7445.AM2012-1525
Abstract 1530: The obligate role of microglia in tumorigenesis in a mouse model of neurofibromatosis-1 optic glioma
Authors: Pong Winnie W. , Higer Samantha B. , Gianino Scott M. , Gutmann David H.
Published: August 2012

Brain tumors (gliomas) are composed of heterogeneous populations of neoplastic and non-neoplastic cells. While the neoplastic cells have classically been the target of therapeutic drug design, recent studies have demonstrated a critical role for non-neoplastic cells in brain tumor growth. The importance of non-neoplastic (stromal) cells is underscored by genetically-engineered mouse (GEM) models of Neurofibromatosis type 1 (NF1)-associated optic glioma. Whereas mice lacking Nf1 gene expression in GFAP+ glial cells do not develop brain tumors, nearly 100% of Nf1+/− mice with GFAP+ cell Nf1 inactivation form optic gliomas. These observations establish an obligate role for Nf1+/− non-neoplastic cells in gliomagenesis. One of the non-neoplastic cell types found in both mouse and human NF1-associated gliomas is microglia, a resident population of macrophage-like cells. To prove that microglia are essential drivers of glioma formation, we generated Nf1 optic glioma mice with reduced expression of the microglial chemokine receptor CX3CR1 (Nf1+/−GFAPCKO-cx3cr1+/GFP mice). Consistent with the critical role of CX3CR1 in microglial function, Nf1+/−GFAPCKO-cx3cr1+/GFP mice had reduced numbers of Iba1+ microglia in the optic nerve. Moreover, Nf1+/−GFAPCKO-cx3cr1+/GFP mice had optic glioma proliferative indices and optic nerve volumes comparable to those found in wild-type mice, demonstrating that microglia are necessary for optic nerve gliomagenesis. Collectively, these findings establish an obligate role for microglia in glioma formation and suggest that CX3CR1 is a potential target for future therapeutic drug design.

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 1530. doi:1538-7445.AM2012-1530
Abstract 1531: Reactive astrocytes promote the growth of cancer stem-like cells of metastatic breast tumor by activating Notch signaling in brain
Authors: Xing Fei , Kobayashi Aya , Okuda Hiroshi , Watabe Misako , Pandey Puspa R. , Pai Sudha K. , Fukuda Koji , Iiizumi Megumi , Watabe Kounosuke
Published: August 2012

Metastatic diseases are responsible for the majority of deaths in breast cancer patients, and brain is one of the most common metastatic sites. The metastatic tumor in the brain profoundly affects the cognitive and sensory functions as well as morbidity of patients, and the one year survival rate among these patients remains less than 20%. However, little is known about the pathogenesis of brain metastasis, and therefore, it is of paramount importance to elucidate the molecular mechanism of metastatic process in order to define a specific therapeutic target. Our analysis of existing microarray database indicate that interleukin-1α (IL-1α) is highly expressed in MDA-MB231BrM2a (231BrM) cell line which is capable of preferentially metastasizing to the brain. IL-1α is known to have an ability of “activating” astrocytes that are often found in the metastatic niche, and therefore, it is speculated that the reactive astrocytes can promote growth and invasion of metastasized cells in the brain. To explore this possibility, we examined the effect of IL-1α and the conditioned medium of 231BrM cells on rat primary astrocytes in vitro. Our results of qRT-PCR and Western blot analysis indicate that IL-1α and the conditioned medium significantly up-regulated the Notch ligand, JAG1, in astrocytes, and that this up-regulation was abrogated by the NF-κB inhibitor, PDTC. We also found that the interaction between CSCs and astrocytes significantly enhances the self-renewal ability of CSCs. To further examine the interaction of astrocytes and tumor cells in the brain, we intracardially injected 231BrM cells in nude mice, and tumor growth was monitored by Xenogen bioimager. After 4 weeks, metastatic tumor growth was observed at multiple sites of the brain, and the results of immunohistochemical analysis indicated that astrocytes adjacent to the metastatic lesions strongly expressed JAG1 and the reactive astrocyte marker, GFAP (Glial fibrillary acidic protein). Finally, we found that a BBB-permeable Notch inhibitor was able to significantly suppress metastatic growth of breast cancer in the brain in our animal model. These results represent a novel paradigm for the understanding of how metastatic breast CSCs re-establish their niche for their self-renewal in a totally different microenvironment, which opens a new avenue to identify a novel and specific target for the brain metastatic disease.

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 1531. doi:1538-7445.AM2012-1531
Abstract 1536: A novel immunocytokine generates a CD8+ T cell-mediated anti-tumor response in vivo
Authors: Fallon Jonathan K. , Tighe Robert , Strittmatter Wolfgang , Sabzevari Helen , Schlom Jeffrey , Greiner John W.
Published: August 2012

Interleukin-12 (IL-12) is a potent TH1 cytokine produced by dendritic cells and macrophages to activate NK cells and T cells. Data from preclinical studies in mice indicate that this cytokine may be useful for the treatment of cancer. However, cases of severe toxicity in human trials have impeded its successful clinical development. Targeting delivery of IL-12 to a tumor while reducing systemic IL-12 exposure could make this a safer, more effective cancer therapeutic agent. One strategy is to conjugate IL-12 to a tumor-binding antibody, as antibody conjugates have previously been used to deliver radioisotopes, other cytokines, and small molecule therapeutics to tumors in vivo. NHS-IL12 is a novel immunocytokine consisting of two molecules of the IL-12 heterodimer covalently fused to a fully humanized antibody (NHS76). This antibody targets necrotic portions of tumors because of its high affinity for single- and double-stranded DNA, which are often exposed as tumors outgrow their blood supply. NHS-IL12 may therefore be useful against a wide range of solid tumors, and mouse models can be used to study its mechanisms of action. Initial imaging studies clearly showed superior in vivo localization of IL-12 to mouse tumors following subcutaneous NHS-IL12 injection as compared to administration of recombinant IL-12 (rIL-12) or IL-12 fused to a control antibody (BC1). In the MC38/CEA+ colorectal carcinoma model in CEA.Tg mice, treatment with NHS-IL12 significantly delayed subcutaneous tumor growth more effectively than treatment with rIL-12. NHS-IL12 did not inhibit MC38/CEA+ tumor cell growth in vitro, suggesting that NHS-IL12 acts indirectly on tumors in vivo most probably via an immune-mediated mechanism. Subsequent findings revealed that tumor-bearing mice treated with NHS-IL12 developed a strong CD8+ T cell response directed against the endogenous p15E tumor antigen. In one study, a subset of mice bearing MC38/CEA+ tumors had complete tumor regression following NHS-IL12 treatment. Each of these mice still had a strong p15E-specific CTL response more than two months after tumor rejection, indicating that p15E may be the major tumor rejection antigen for this in vivo tumor model. Subsequent in vivo depletion studies are planned to investigate which immune cell subsets contribute to the anti-tumor efficacy of this agent. Taken together, these data show that targeted delivery of IL-12 to tumors can overcome the immunosuppressive tumor microenvironment and prime a robust CD8+ T cell response. These findings suggest that NHS-IL12 may be a promising cancer therapeutic as a single agent and/or as a potent vaccine adjuvant.

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 1536. doi:1538-7445.AM2012-1536
Abstract 1551: Targeting myeloid derived suppressor cells as novel strategy to enhance immunotherapy in murine prostate cancer models
Authors: Shen Li , Ciesielski Michael , Miles Kiersten M. , Ellis Leigh , Fenstermaker Robert , Pili Roberto
Published: August 2012

Purpose: Myeloid derived suppressor cells (MDSCs) are a major component of the immunosuppressive environment responsible for immune tolerance in cancer. These cells facilitate carcinogenesis and tumor progression by impairing T and NK cells activation and contributing to regulation of angiogenesis. In current study, we evaluated whether accumulation of MDSCs occur in two murine prostate cancer models: a castrate resistant, syngenic transplantable tumor (CR Myc-Cap) and the Hi-myc transgenic tumor models. Tasquinimod is an anti-angiogenic agent tested in prostate cancer and has been found to bind to an inflammatory protein S100A9 and therefore have the potential to affect accumulation and function of MDSCs. We investigated whether tasquinimod affects the induction and function of MDSCs and facilitate vaccine therapy in these castrate resistant prostate cancer models. Experimental design: Splenocytes and blood cells were isolated from naïve and CR Myc-Cap tumor bearing mice. Blood samples were taken from Hi-myc transgenic mice and age-matched littermates at different ages. All these splenocytes and blood samples were subjected to staining with MDSCs markers, Gr1 and CD11b, and to flow cytometry analysis. CR Myc-Cap tumor bearing mice were treated with either vehicle, tasquinimod (1mg/kg), modified survivin vaccine peptide SurVaxM, or combination. Tumor growth, MDSCs accumulation and function upon treatments were monitored. Results: The peripheral MDSCs (in blood and spleen) significantly increased in tumor bearing mice. The MDSCs number increase correlated with disease progression in the transgenic model. Low doses of tasquinimod (1-5mg/kg) did not change the CD11b+Gr1high MDSCs number, but CD11b+Gr1high, CD11b+Gr1int, CD11b+Gr1− cells were differently accumulated in vehicle or tasquinimod treated mice. Tasquinimod in vivo treatment reduced peripheral CD11b+Gr1int, CD11b+Gr1− cells number. Low doses of tasquinimod have minimal effect on CD11b+Gr1high MDSCs function and did not enhance the SurVaxM vaccine therapy in CR Myc-Cap model.Conclusions: In summary, our study demonstrates MDSCs accumulation in two prostate cancer models and suggests that MDSCs may contribute to immune tolerance in prostate cancer. The study also suggests low dose tasquinimod affect maturation of MDSCs into other immunosuppressive cell types (CD11b+Gr1int, CD11b+Gr1−). Higher doses of tasquinimod (≥10mg/kg) are being tested for their potential to affect MDSCs accumulation and function in prostate cancer models.

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 1551. doi:1538-7445.AM2012-1551
Abstract 1812: Development of Erlotinib derivatives as CIP2A inhibitors
Authors: Shiau Chung-Wai
Published: August 2012

PP2A is a protein phosphatase which involves in negatively regulating cell proliferation, survival and differentiation. Literature has shown that cancerous inhibitor of PP2A (CIP2A) is an inhibitor of PP2A in cancer cells. Overexpression of CIP2A contributes to tumor aggressiveness and renders resistance to chemotherapy. Inhibiton of CIP2A by small molecules shut off the downstream signal pathway of Akt through increasing PP2A phosphatase activity. For example, Bortezomib, a poteasome inhibitor, suppressed expression level of CIP2A and further reduced phospho-Akt in hepatocellular carcinoma cells. Hence, Agents that can repress CIP2A have potentials for the treatment in cancers. Erlotinib, an EGFR inhibitor, shows therapeutic effects in clinical. Our data show that CIP2A represents a major factor whereby erlotinib derivatives induce apoptosis in HCC cells. Here, a series of mono- and di-substituted erlotinb derivatives were synthesized and their bioactivities against hepatocellular carcinoma were evaluated. The di-substituted erlotinib derivatives were more potent inhibitors of cancer-cell proliferation than the mono-substituted derivatives. Further assays confirmed a correlation between cell death, and CIP2A and Akt inhibition by these derivatives. Among them, compound 19 provides a proof of concept for the design of a new class of agents that repress CIP2A activity in HCC.

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 1812. doi:1538-7445.AM2012-1812