bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 2416: The effects of methylation-controlled DnaJD1 in hepatitis B virus X protein expressed hepatocellular carcinoma
Authors: Lai Yi-Wen , Chen Jeremy, J.W. , Chen Hsiao-Ling , Chen Chuan-Mu
Published: June 2012

The development of hepatocllular carcinoma (HCC) is a multistep process with accumulation of genetic and epigenetic alternations in regulatory genes, leading to activation of oncogenes and inactivation of tumor suppressor genes. In our studies, we used non-commercial MCGI (mouse CpG islands) microarray to identify many genes that were hypermethylation in the liver tumor tissues of HBx-overexpressed transgenic mice, and examined the mehtylation pattern on these selected genes by bisulfite sequencing. According to the methylation analysis results, we focused on a methylation-controlled DNAJ family (MCJ) gene, DnaJD1. It was found hypermethylation in the promoter region and followed reduced mRNA expression in Hep3B hepatoma cells, which contain HBV genome. The HBV or HBx was involved in epigenetic modification during HCC tumorgenesis still not clear. In our previous research results, we are looking forward to realize the DnaJD1 characters in HBx expressed HCC. Consequently, the over-expressed DnaJD1 in Hep3B cells were established and investigated the physiologic effects of DnaJD1 in cell proliferation, cell migration, and invasion ability in vitro. In addition, DnaJD1 shRNA fragments were also applied to realize the related roles of DnaJD1 in DnaJD1 over-expressed Hep3B cells. Data suggested that DnaJD1 re-expressed in Hep3B cells that could effect the cell physiological characterizations, and the semi-quantitative RT-PCR results showed DnaJD1 could effect the HBx gene expression. Furthermore, the tumorgenesis in xenotransplanted nude mice were also examined. In these results, we concluded that DnaJD1 could display the important role in HBx expressed HBV-related hepatocellular carcinoma.

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 2416. doi:10.1158/1538-7445.AM2011-2416
Abstract 2419: Glycogen synthase kinase-3 inhibitor and cisplatin synergically inhibit tumor growth of Urothelial cancer in xenograft rodent model
Authors: Naito Sei , Bilim Vladimir , Kawazoe Hisashi , Tomita Yoshihiko
Published: June 2012

Introduction: Glycogen synthase kinase-3beta (GSK-3beta) is a serine/threonine kinase, as a positive regulator of several cancer cell survival and proliferation. We previously showed that nuclear accumulation of GSK-3beta indicates high grade, high stage, and poor survival in bladder urothelial cancer (UC). And inhibition of GSK-3beta suppresses UC cell proliferation and induces apoptosis via NF-kappaB down-stream genes viz. BCl-2 and XIAP (Clin Cancer Res 2010). Here we were to identify the interaction between cisplatin and GSK-3 inhibitor, AR-A014418 in UC.

Experimental Procedures: We added cisplatin (0, 1, 3, 6 μg/ml) and AR-A014418 (0, 10, 20 μM) to medium in T24 and HT1376 human UC cells and assessed their viability by MTS assay. Furthermore, we intraperitoneally administrated PBS 5 time per week, 2.5 mg/kg body weight cisplatin once per week, 20 mg/kg body weight AR-A014418 5 time per week, or cisplatin and AR-A014418 into each 6 mice with subcutaneous xenografts of HT1376 for 3 weeks.

Result: Treatment of cisplatin and AR-A014418 showed synergistic effect in cell lines. Cisplatin did not change expression level of GSK-3beta, and AR-A014418 suppressed XIAP for cell lines with cisplatin. The average tumor volume of the mice treated by cisplatin was equivalent to one by PBS within treatment period. However, the tumors treated by cisplatin grew bigger than ones by PBS after withdrawal of treatment. AR-A014418 inhibited the growth of tumor compared to PBS and cisplatin. And combine use of cisplatin and AR-A014418 prevented the tumor from re-growth by cisplatin after treatment. Body weight did not vary between mice by each treatment methods.

Conclusion: Cisplatin and AR-A014418 synergistically suppressed UC cells viability. And AR-A014418 cancelled re-growth of low-dose cisplatin in xenograft model.

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 2419. doi:10.1158/1538-7445.AM2011-2419
Abstract 2425: Mechanisms of neuroblastoma metastasis to bone
Authors: Carter Larry , Varin Courtney , van Golen Cynthia M.
Published: June 2012

The molecular pathways leading to neuroblastoma (NBL) development and progression are understudied despite the fact this tumor is responsible for 15% of all childhood cancer deaths. Bone is one of the most common sites of metastasis in NBL, and over 90% of children with NBL bone metastasis will die. Therefore, the goal of this study is to elucidate the cell-signaling pathways responsible for the destruction of bone. Parathyroid hormone related protein (PTHrP) and Transforming Growth Factor Beta both are involved in osteoclastogenesis. PTHrP travels through the circulation to the bones, where it triggers a chain of event that encourages the dissolution of bone minerals by osteoclast. Moreover, PTHrP results in the mobilization of calcium ions, which travel back via the circulatory system allowing osteoclast differentiation to go unchecked, therefore providing further destruction to the bone microenvironment. Transforming Growth Factor Beta (TGF-β) is a protein which controls proliferation, cellular differentiation and other functions in most cells. Since TGF-β and the SMAD family of proteins modulate the activity TGF-β and its association with osteoclasts, we formulated the hypothesis that osteoclastogenesis occurs during NBL bone metastasis through PTHrP and TGF-β. NBL is a heterogeneous tumor consisting of neuronal (n) and stromal (s) cells, with metastatic cells predominantly of the n type. In our study, we focused on four NBL cell lines: IMR-32 (n), SH-SY5Y (n), SK-N-AS (s), SK-N-SH (s). Conditioned media collected from IMR32 NBL cells induces osteoclast precursors to fuse into multinucleated, TRAP positive cells, indicative of osteoclast differentiation. Whole cell lysates were collected and Western immunoblotting performed for PTHrP. We report that the more tumorigenic cells, SH-SY5Y and IMR32, express higher levels of PTHrP than the s lines SK-N-AS and SK-N-SH. These data indicate that PTHrP may be involved in NBL bone metastasis. We are currently analyzing the effects of TGF-β on NBL and the role of these proteins in NBL-induced osteoclastogenesis.

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 2425. doi:10.1158/1538-7445.AM2011-2425
Abstract 2449: Pancreatic cancer tumor initiating cells are marked by the presence of a primary cilium
Authors: Bailey Jennifer M. , Rasheed Zeshaan , Matsui William , Maitra Anirban , Hollingsworth Michael A. , Leach Steven D.
Published: June 2012

Primary cilia are microtubule rich projections eminating from the apical surface of epithelial cells. Primary cilia are responsible for the transduction of growth factor and morphogenetic signaling pathways, including the hedgehog, wnt and platelet-derived growth factor pathways. Initial observations in the field of pancreatic cancer have suggested the absence of primary cilia in human pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma. While absent in the majority of pancreatic cancer cells, primary cilia have been identified in differentiated acinar cells undergoing an acinar to ductal metaplasia. This metaplasia is well characterized in pancreatic injury and regeneration models and accelerates tumor formation in the presence of acinar specific KrasG12D mutations. Thus, we are addressing the hypothesis that primary cilia, while not expressed in bulk tumor populations, are maintained in pancreatic tumor-initiating cells. To address the hypothesis, we have used confocal microscopy to quantify the percentage of cells within low grade human PanIN lesions that express a primary cilium. Performing confocal microscopy on a human PanIN tissue array (n=23), we have determined that in 15% of PanIN lesions, 13-30% of the cells are expressing a primary cilium, as is evidenced by staining for acetylated alpha tubulin. We have also developed a sorting strategy using an acetylated alpha tubulin antibody to isolate ciliated cells by Fluorescence Activated Cell Sorting (FACS) analysis. Using this protocol, we have discovered that human pancreatic cancer cells bearing a primary cilium are markedly enriched in cells also positive for either CD133 or CD24/CD44, representing putative pancreatic cancer stem cell populations. We have functionally analyzed the tumor-initiating capacity of ciliated vs non-ciliated cells using tumor sphere experiments. In this assay, ciliated cells show a significant increase (100 fold) in tumor sphere-forming capacity, suggesting that the presence of a primary cilium may mark a pancreatic cancer tumor initiating population. These data are informative regarding the earliest initiating events in pancreatic cancer.

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 2449. doi:10.1158/1538-7445.AM2011-2449
Abstract 2464: Targeting liver cancer stem cells for molecular imaging and therapeutic application
Authors: Wang Lina , Liu Ze , Lu Dan , Chen Si , Li Na , Xiang Rong , Li Zongjin
Published: June 2012

Conventional therapies target rapidly proliferating non-tumorigenic cells and spare the relatively quiescent cancer stem cells (CSCs) and the CSCs will remain viable after therapy and re-establish the tumor. Thus developing therapeutic strategies to target CSCs to prevent tumor recurrence will be vital for cancer therapy. To date, it has been shown that CSCs in hepatocellular carcinoma (HCC) can be identified by several cell surface antigens CD133, CD90, CD44, OV6 and the epithelial cell adhesion molecule (EpCAM). Here, we developed a novel strategy which targeted CSCs by anti-CD44 antibody mediated nanoparticles delivery system loaded with a triple fusion gene containing the suicide gene-herpes simplex virus truncated thymidine kinase (TTK), renilla luciferase (RL) and RFP (TF, RL-RFP-TTK). The in situ liver cancer model was established by injection of 1.0×105 HepG2 cells, which carry a reporter system encoding the genes of firefly luciferase (FL) and GFP into the liver of NOD/SCID mice. The mice were subsequently treated with ganciclovir (GCV). Then the growth status of tumor was monitored by the optical bioluminescence imaging of firefly luciferase(FL) and the specific targeting of the nanoparticles was tracked by imaging of renilla luciferase(RL). Our results demonstrated that the anti-CD44 antibody mediated nanoparticles loaded with TTK could specifically target the CSCs of HCC, and thereafter were endocytosed by the plasma membrane to transport the triple fusion (TF, RL-RFP-TTK) into the cells, resulted in the apoptosis of the targeted cells. Taken together, our study demonstrated a novel therapeutic strategy by targeted CSCs, we also developed a useful multimodality imaging techniques to monitor HepG2 cells’ fate in vivo and assessed the targeting efficacy of the nanoparticles. This may open a new application for the treatment of the HCC by targeting CSCs.

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 2464. doi:10.1158/1538-7445.AM2011-2464
Abstract 2467: Podoplanin expressing cancer stem cells show increased resistance to DNA damage induced by ionizing radiation
Authors: Ezhilarasan Ravesanker , Love Patrice N. , Goodman Lindsey D. , Aldape Kenneth D. , Sulman Erik P.
Published: June 2012

The majority of patients with malignant gliomas, the most common and most lethal brain tumor, develop disease recurrence despite aggressive, multi-modality therapies. This treatment resistance has been attributed to a small population of tumor-initiating glioma cancer stem cells (GSCs). We recently described a new marker of GSCs, the transmembrane glycoprotein podoplanin (pdpn), based on analysis of gene expression profiling data and have found it to be more accurately identify the stem cell population than other described markers. Pdpn expression correlates with poor patient survival and decreased response to radiotherapy. Pdpn expressing cells form neurospheres at high rates in vitro, are more resistant to ionizing radiation, and initiate tumors in vivo. Silencing of pdpn leads to increased radiosensitivity. To identify the mechanism of radiation resistance in pdpn-expressing GSCs, we screened for putative binding partners and identified target of myb-like-1 (tom1l1), a known regulator of Src-pathway activation. We hypothesized that modulation of pdpn and/or tom1l1 expression would lead to alternations in the response of GSCs to radiation via src signaling. Mechanisms of radiation resistance in GSCs are poorly understood to date and the role of src family kinases in modulating radiosensitivity has not previously been reported in gliomas. Pdpn binding of tom1l1 was confirmed by co-immunoprecipation and src activation monitored by immunoblot. Pdpn and tom1l1 expression was downregulated by RNA interference and dsDNA damage and repair assayed by neutral comet assay and by scoring of γH2AX foci. Silencing of pdpn in primary culture, neurophere forming GSC-like cells resulted in increased DNA damage following 2 and 6 Gy ionizing radiation. We similarly examined effects of decreased tom1l1 to determine if the effects on DNA repair mediating by pdpn were acting via the src pathway. In summary, our data suggest that pdpn expression correlates with increased dsDNA repair following ionizing radiation and presents a possible mechanism by which GSCs resist treatment and regrow the tumor.

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 2467. doi:10.1158/1538-7445.AM2011-2467
Abstract 247: A novel mPGES-1/EGR1/beta-catenin signaling axis in hepatocarcinogenesis
Authors: Lu Dongdong , Han Chang , Wu Tong
Published: June 2012

Microsomal prostaglandin E synthase-1 (mPGES-1) is a key enzyme that couples with cyclooxygenase-2 (COX-2) for the production of PGE2. Although COX-2-derived PGE2 is known to participate in the development and progression of several human cancers including hepatocellular carcinoma (HCC), the role of mPGES-1 in carcinogenesis remains poorly understood. This study provides novel evidence for an important role of mPGES-1 in human HCC. Forced overexpression of mPGES-1 in two HCC cell lines (Hep3B and Huh7) promoted tumor cell growth and increased clonogenic formation capacity, in vitro. Conversely, mPGES-1 knockdown inhibited tumor cell growth and prevented clonogenic formation. Overexpression of mPGES-1 in Hep3B and Huh7 cells also increased cell invasion and migration/repair capacity, whereas knockdown of mPGES-1 reduced these parameters. Flowcytometric analysis revealed that mPGES-1 knockdown caused cell cycle arrest at G1/S checkpoint. In SCID mouse tumor xenograft model, mPGES-1 overexpressed cells formed palpable tumors at earlier time points and developed larger tumor nodules when compared to the control cells (p<0.01); in contrast, mPGES-1 knockdown delayed tumor development and reduced tumor growth in SCID mice (p<0.01). Mechanistically, mPGES-1-induced HCC cell proliferation, invasion and migration involve activation of EGR1 and beta-catenin. mPGES-1 induced the formation of EGR1-beta-catenin complex, which interacted with TCF4 transcription factors in HCC cells. Our findings depict a novel mPGES1/EGR1/beta-catenin signaling axis that is crucial in hepatocarcinogenesis.

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 247. doi:10.1158/1538-7445.AM2011-247
Abstract 2485: The Hippo downstream effector YAP promotes survival, radiation resistance and chromosome instability in medulloblastoma
Authors: Fernandez-L Africa , Kenney Anna M.
Published: June 2012

Medulloblastoma, the most common solid pediatric tumor, originates in the cerebellum during postnatal development. It is postulated that cerebellar granule neuron precursors (CGNPs) are cells-of-origin for certain classes of medulloblastomas. CGNPs require the mitogen/morphogen Shh to proliferate. We identified YAP as a new Shh target that promotes CGNP proliferation. YAP is a transcriptional co-activator negatively regulated by the Hippo pathway, a signaling cascade involved in organ size regulation and cell contact inhibition. We found YAP to be highly expressed in human and mouse Shh-driven medulloblastomas. Moreover, YAP was strikingly amplified in a subset of human medulloblastomas. YAP was localized to the peri-vascular niche where cancer stem cells have recently been described to reside in brain tumors. When we irradiated medulloblastoma-bearing mice, most of the cells in the tumor underwent apoptosis 6 hours after radiation. However, cells expressing YAP were resistant to radiation-induced apoptosis. These radiation-resistant cells have been described to have the ability to re-populate the tumor. In concordance with this, mouse medulloblastoma cells over-expressing YAP and injected in P0-P4 pups grow faster than those overexpressing GFP and give rise to more aggressive tumors. In vitro, YAP-overexpressing CGNPs and medulloblastoma cells produce higher levels of IGF2, which activates Akt and promotes their survival. 24 hours after radiation, YAP-overexpressing cells contain more damaged DNA; however, they skip the G2/M checkpoint and don't arrest despite the damage in their DNA. Our results indicate that YAP promotes both chromosome instability and survival of medulloblastoma cells, thus is a new attractive potential target for medulloblastoma therapies.

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 2485. doi:10.1158/1538-7445.AM2011-2485
Abstract 2489: Targeting pro-survival BCL-2 family members increases radiation sensitivity in breast cancer cells
Authors: Wu Hao , Schiff Devora S. , Goyal Sharad , Neboori Hanmanth J.R. , Haffty Bruce G.
Published: June 2012

In previous studies we have shown that BCL-2 expression was associated with an increased risk of local recurrence in patients with early stage breast cancer (Yang Q, Breast Cancer Res Treat, 2009). Additionally, BCL-2-overexpressing lymphoma and prostate cancer cell lines were resistant to radiation-induced apoptosis. The BCL-2 family encompasses two groups: the pro-survival group (BCL-2, BCL-XL, BCL-w, MCL-1, A1) and pro-apoptotic group (BAK, BAX, BAD, BIK, etc.) ABT-737 is a BH3 mimetic compound that targets the pro-survival members excluding MCL-1. Targeting pro-survival BCL-2 family members presents an attractive novel adjuvant therapeutic option. The purpose of this study was to explore an approach to overcoming radiation resistance by targeting pro-survival BCL-2 family proteins in breast cancer cells. First, siRNAs were employed to target BCL-2 in MCF-7 and BT474 breast cancer cells. Apoptosis was determined by detecting cleaved PARP after siRNA and radiation treatment. Cleaved PARP in BCL-2 siRNA treated MCF-7 cells increased compared to non-targeting siRNA treated cells 72 hours after 8Gy of radiation, indicating the targeting BCL-2 alone increased apoptotic cell death. Despite evidence of increased radiation related apoptosis, cell viability showed there was no significant difference between BCL-2 siRNA and non-targeting siRNA treated MCF-7 cells at 2, 4, 6 and 8Gy, p>0.05, indicating that targeting the BCL-2 alone did not enhance radiation sensitivity. However, the combination of radiation (8Gy) and ABT-737 (variable doses) enhanced BAK and cleaved PARP at 24hr, 48hr and 72hr. Further, the cell viability of the combination of radiation (2Gy) and ABT-737 (5µM) significantly decreased 16.5%, p<0.01 and 26.5%, p<0.01, compared with radiation alone or ABT-737 alone treated MCF-7 cells, respectively. Similar results were observed in T47D and MDA-MB231 cells. Finally, after knocking down MCL-1 by siRNA, cell viability went down in 14.5% (p<0.05) in MCL-1 siRNA treated MCF-7 cells compared with non-targeting siRNA treated cells at 5µm of ABT-737. In addition, MCL-1 protein level decreased after treatment of radation alone and the combination of radiation and ABT-737 in MCF-7, MDA-MB 231 and ZR75-1 cells. Together, our results showed that synergistic effect of radiation and ABT-737 on breast cancer cell lines through down-regulating MCL-1 and activating bak-apoptotic pathway. These results support the combination of radiation and pro-survival BCL-2 family inhibitor as a potential novel therapeutic strategy in breast cancer treatment.

Supported by the Breast Cancer Research Foundation

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 2489. doi:10.1158/1538-7445.AM2011-2489
Abstract 2501: PEGylated human recombinant hyaluronidase (PEGPH20) enhances radiotherapy in hyaluronan-rich solid tumors
Authors: Bahn Jesse D. , Skipper James , Garcia Arnie , Jiang Ping , Osgood Ryan , Symons Rebecca , Frost Gregory I. , Shepard H. , Thompson Curtis B. , Li Xiaoming
Published: June 2012

The accumulation of the glycosaminoglycan hyaluronan (HA) in the extracellular matrix (ECM) of solid tumors contributes to increased tumor interstitial fluid pressure IFP), localized edema and reduced intratumoral blood flow. We recently reported that sustained enzymatic depletion of tumor HA with a pegylated recombinant human hyaluronidase PH20 (PEGPH20) decreases tumor IFP and water content, while significantly increasing vascular perfusion within HA-rich prostate PC3 tumors (Thompson et al, 2010). As localized tissue hypoxia reduces the effectiveness of radiation therapy (Baumgartner et al, 1998), we hypothesized that PEGPH20 treatment would reduce tumor hypoxia, thereby radio-sensitizing tumor cells. To evaluate whether PEGPH20 sensitizes HA-rich tumors, radiotherapy resistant human prostate PC3 cells (2×106) were inoculated into the right tibia periosteum of nude mice (NCR nu/nu) and tumor growth monitored with a high resolution 3D ultrasound. When the tumors reached ∼800 mm3 (n ≥ 8/group), mice were staged into 4 treatment groups: (1) vehicle control; (2) mono-radiotherapy at 2.5 Gy, q3d; (3) PEGPH20 monotherapy, 4.5 mg/kg, i.v. q3d; or (4) PEGPH20 plus radiotherapy. To increase intra-tumoral blood flow, PEGPH20 was administrated 3 hours prior to radiation therapy. Histological evaluation of a subset of mice confirmed that HA was completely degraded 3 hours post- PEGPH20 treatment. At study Day 15, tumor growth inhibition (TGI) with radiation alone or PEGPH20 alone was 99.2% (p=0.009) and 71.4% (p=0.08), respectively, relative to vehicle treated animals. PEGPH20 plus radiotherapy inhibited tumor growth by 140.6% (p=0.0002), relative to vehicle treated animals. The mean tumor size of the PEGPH20 plus radiotherapy group was reduced to ∼550 mm3, with 3-out-of-8 partial regressors (i.e. tumor size decrease to 50% or less of tumor staging size). These findings suggest that PEGPH20-mediated HA removal, and subsequent increase in tumoral blood flow, may increase the efficacy of radiation therapy in hyaluronan-rich tumors.

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 2501. doi:10.1158/1538-7445.AM2011-2501
Abstract 2511: Glycogen synthase kinase 3 beta inhibitors protect hippocampal neurons from radiation-induced apoptosis by regulating MDM2/p53 pathway
Authors: Thotala Dinesh Kumar , Hallahan Dennis E. , Yazlovitskaya Eugenia M.
Published: June 2012

Exposure of the brain to ionizing radiation can cause neurocognitive deficiencies. The pathophysiology of these neurological changes is complex and includes radiation-induced apoptosis in the subgranular zone of the hippocampus. We have recently found that inhibition of glycogen synthase kinase 3β (GSK-3β) resulted in significant protection from radiation-induced apoptosis in hippocampal neurons. The Molecular mechanisms of this cytoprotection include abrogation of radiation-induced accumulation of p53. Here we show that pretreatment of irradiated HT-22 neurons with small molecule inhibitors of GSK-3β SB216763 or SB415286, or with GSK-3β-specific shRNA resulted in accumulation of the p53-specific E3 ubiquitin ligase MDM2. Knockdown of MDM2 using specific shRNA or chemical inhibition of MDM2 prevented the protective changes triggered by GSK-3β inhibition in irradiated HT-22 and restored radiation cytotoxicity. We found that this could be due to regulation of apoptosis by subcellular localization and interaction of GSK-3β, p53 and MDM2. These data suggest that the mechanisms of radioprotection by GSK-3β inhibitors in hippocampal neurons involve regulation of MDM2-dependent p53 accumulation and interactions between GSK-3β, MDM2 and p53.

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 2511. doi:10.1158/1538-7445.AM2011-2511
Abstract 2519: A class of biometallo-organic compounds that target human topoisomerase IIa
Authors: Fagenson Alexander M. , Akerman Matthew P. , Munro Orde , Muller Mark T.
Published: June 2012

Topoisomerase IIa (topo II) is a nuclear enzyme that changes the topological state of DNA by breaking and rejoining the phosphodiester backbone of DNA. It is an important target for anticancer therapy and a number of agents are known to influence its action in vivo. These agents operate by either disrupting the cleavage-resealing cycle (interfacial poisons) or by simply blocking catalytic action of topo II (catalytic inhibitors). A new class of metallo-drugs is described that is unique in acting by both mechanisms. These are a series of fully characterized crystalline d8 coordination compounds with tetradentate ligands that we have evaluated for their targeting potential with topo II. These compounds are quite toxic to cells in culture with inhibitory values in low micromolar range. Mechanistic in vitro data with purified enzyme reveal these compounds to act as both catalytic inhibitors and as interfacial poisons over the same range of drug concentration. For example, CC50 values (drug concentrations yield 50% maximum DNA cleavage) were 3.47 µM for the prototype metallo-agent (compared to 5.47 µM for etoposide). Acting as catalytic inhibitors, the IC50 value was 3.17 µM. In sum, these compounds exhibit dual mechanisms in vitro, by stabilizing the covalent cleavage complex as well as blocking catalytic function. Analysis of endogenous topo II activity in HeLa cells confirms that the compounds target endogenous topo II by stabilizing the covalent cleavage complex and therefore acting as a poison in a cellular context. Endogenous topo I was not affected by the drug showing that these novel metallo-agents are type II specific. The dual mechanism of targeting of topo II suggests significant anti-tumor potential, and further studies are being conducted to evaluate clinical potential.

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 2519. doi:10.1158/1538-7445.AM2011-2519
Abstract 2522: Therapeutic synergism of cabazitaxel in combination with cisplatin in tumor-bearing mice
Authors: Vrignaud Patricia
Published: June 2012

Cabazitaxel (Jevtana), a semi-synthetic taxane derived from 10-deacetyl baccatin III, is as efficient as docetaxel in promoting tubulin assembly in vitro and stabilizing microtubules against cold-induced depolymerization. Cabazitaxel was selected for clinical development based on better antiproliferative activity than docetaxel against chemotherapy resistant tumor-cell lines (Bissery M.C. et al, AACR 2000) and a broad spectrum of in vivo antitumor activity (Vrignaud P. et al, AACR 2000), not only in docetaxel-sensitive tumor models, such as the human gastric N87 xenograft, but also in tumors models in which docetaxel was either poorly active or inactive. As an example, cabazitaxel was highly active in mice bearing UISO-BCA1 tumors, a human mammary xenograft expressing Her-2, which is poorly sensitive to ixabepilone and not sensitive to docetaxel. In addition, cabazitaxel penetrates the blood brain barrier (Cisternino S. et al, British J. Pharm. 2003) and has marked antitumor activity in nude mice bearing intracranial glioblastomas (Dykes D.J. et al, AACR 2000). Cabazitaxel was recently approved by the FDA for patients with metastatic hormone-refractory prostate cancer previously treated with docetaxel-based therapy.

In order to explore other therapeutic indications, the cabazitaxel-cisplatin combination was evaluated in C51 tumor-bearing mice. A 5-arm dose-response study was performed with cabazitaxel and cisplatin administered IV on days 5 and 12 after tumor implantation as single agents and in combination using 3 different sequences of administration: simultaneous in group A and sequentially separated by a 24h interval in groups B (cabazitaxel first) and C (cisplatin first). At their highest nontoxic doses (HNTD), both single agents were found active with tumor growth delays (T-C) of 15.2 days for cabazitaxel at 20 mg/kg/inj and 22.1 days for cisplatin at 4.3 mg/kg/inj. The 3 combination arms showed greater antitumor activity at their respective HNTD with T-C of 38.4 days in group A, 37.8 days in B, and 36.2 days in C. Of interest, 2 (A) and 3 (B & C) dose levels were found more active than the single agents in the combination arms.

In conclusion, a therapeutic synergism was achieved when cabazitaxel was combined with cisplatin in C51 tumor-bearing mice. These data are supporting the ongoing Phase I clinical study of cabazitaxel-cisplatin combination in solid tumors.

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 2522. doi:10.1158/1538-7445.AM2011-2522
Abstract 2528: Therapeutic targeting of a novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate to human solid tumors based on selective uptake by PCFT
Authors: Desmoulin Sita Kugel , Wang Lei , Tait Larry , Polin Lisa , Hou Zhanjun , Cherian Christina , Gangjee Aleem , Matherly Larry H.
Published: June 2012

The proton-coupled folate transporter (PCFT) is a proton-folate symporter with an acidic pH optimum, such that PCFT may provide a mechanism for targeting cytotoxic antifolates to tumors, based on their acidic microenvironments (pH 6.2-6.8). PCFT transcripts and protein are high in human solid tumor tissues and cell lines (especially hepatic and ovarian tumors) and limited in most human normal tissues. We identified a novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate (AG71) that is a selective transport substrate for PCFT over the ubiquitously expressed reduced folate carrier (RFC) and a potent inhibitor of the de novo purine nucleotide biosynthetic enzyme glycinamide ribonucleotide (GAR) formyl transferase (GARFTase). Both AG71 and the clinically relevant antifolate pemetrexed (Pmx) were potently inhibitory toward proliferation of a HeLa subline (R1-11-PCFT4) that lacked RFC expression and was engineered to ectopically express physiologically relevant PCFT levels. Unlike Pmx, AG71 did not inhibit proliferation of R1-11-RFC6 cells which express physiologically relevant RFC levels but no PCFT. In colony-forming assays at pH 6.8, AG71 inhibited colony formation of R1-11-PCFT4 cells in a dose- and time-dependent manner, comparable to Pmx. We measured uptake of [3H]AG71 in R1-11-PCFT4 cells and found that transport was optimal at pH 5.5 but still significant at pH 6.8. At pH 6.8, AG71 was metabolized by folylpoly-γ-glutamate synthase to AG71 polyglutamates, as detected by HPLC. GARFTase was validated as a major intracellular target with an in situ GARFTase activity assay at pH 6.8 involving [14C]glycine incorporation into [14C]formyl GAR. In HepG2 human hepatocellular carcinoma cells, PCFT levels were elevated and [3H]AG71 was transported at pH 6.8, whereupon it was extensively metabolized to polyglutamates. By proliferation assays, AG71 was potently inhibitory (IC50 of 227.5 nM) toward HepG2 cells. To test in vivo efficacy of AG71, SCID mice were implanted with subcutaneous HepG2 tumors and treated with AG71 (180 mg/kg × 3d). Compound AG71 was highly active against HepG2 tumors. In conclusion, we have established the expression patterns and pH-specific transport for PCFT in human solid tumor cells and demonstrated that the novel PCFT-targeted antifolate AG71 can be internalized into tumor cells by PCFT leading to significant growth delay of HepG2 xenografts. Our findings offer exciting new therapeutic possibilities for selectively targeting chemotherapy to tumors with novel antifolates based on their acidic microenvironments.

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 2528. doi:10.1158/1538-7445.AM2011-2528
Abstract 2534: Novel and stable water-soluble N-mustards with potent therapeutic efficacy against human tumor xenografts in nude mice
Authors: Su Tsann-Long , Kakadiya Rajesh , Dong Huajin , Chen Yi-Ren , Lee Pei-Chih , Chou Ting-Chao , Hsiao Pei-Wen , Lee Te-Chang , Marvania Bhavin
Published: June 2012

The bioavailability of drugs is one of the important factors to determine whether a drug can be successfully developed for clinical application. Consequently, the physicochemical properties, including solubility, permeability, stability pKa, and lipophilicity/hydrophilicity balance, are key factors that influence the bioavailability of drugs. Compounds with poor solubility usually have a higher risk of difficulties to overcome during the period of new drug discovery and development because these properties may affect antitumor evaluations in animal models as well as pharmacokinetic and pharmacodynamic properties of the compound. In the present studies, we have synthesized a series of novel water-soluble N-mustard-benzene conjugates bearing a urea linker were synthesized. The benzene moiety contains a variety of hydrophilic side chains. These side chains are linked to the meta- or para-position of the urea linker via a carboxamide or an ether linkage. Compounds having a carboxamide hydrophilic side-chain can be converted into water-soluble hydrochloride or mesylate. The preliminary antitumor studies revealed that these conjugates exhibited potent cytotoxicity in vitro and antitumor therapeutic efficacy against human tumor xenografts in vivo. Furthermore, these derivatives have little or no cross-resistance to either Taxol or Vinblastine. Among these conjugates, compound WS-1707, which bearing a N,N-dimethylaminoethylcarboxamide hydrochloride water-soluble side-chain possessed potent therapeutic efficacy in nude mice bearing human breast carcinoma MX-1 (Remarkably, complete tumor remission in nude mice bearing human breast carcinoma MX-1 xenograft (complete tumor remission), prostate adenocarcinoma PC-3 xenograft (>99% suppression), and human colon cancer HCT-116 xenograft (>95% suppression) at the maximal tolerable dose 30 mg/kg, Q2D×5, intravenous injection. We also compared the therapeutic potency of WS-1707 with Carbopltin, and Doxetaxol in nude mice bearing prostate cancer HL2 xenograft (orthotopic implantation). It reveals that WS-1707 is as potent as Doxetaxol (>82% tumor suppression), but significantly more potent than Carboplatin. Study on the mechanism of action that this agent is able to induce DNA cross-linking through alkaline agarose gel shift assay. Early pharmacokinetic study shows that this conjugates has acceptable profile in rats with a half-life of 0.56 h. These results suggest that this agent is a promising candidate for preclinical studies.

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 2534. doi:10.1158/1538-7445.AM2011-2534
Abstract 2556: Indole-3-carbinol (I3C) and gemcitabine as potential combinatorial therapy in pancreatic cancer
Authors: Lyn-Cook Beverly , Mohammed Sulma , Word Beverly , Hammons George
Published: June 2012

Pancreatic cancer has a poor prognosis, mainly due to lack of effective therapies. The use of non-toxic dietary agents in combination with standard treatment is showing promise in several highly deadly cancers. This study demonstrated the ability of dietary agent, indole-3-carbinol (I3C), to lower the LD50 of gemcitabine (Gemzar) and significantly decrease the growth of both male (MiaPaca2) and female (SU86.86) pancreatic cancer cells. In the male cell line (MiaPaca2) I3C enhanced the anti-proliferative effect at lower doses, decreasing gemcitabine IC50 from 30nM alone to 3nM in combination, a ten-fold decrease in the amount of gemcitabine needed to kill a significant number of cancer cells. Sex difference in response to gemcitabine was also demonstrated. Pancreatic cancer cells from the female cell line (SU86.86) were highly resistant to gemcitabine alone and growth was not affected even at doses as high as 500 μM compared to another powerful anti-cancer drug, doxorubicin (IC50=2.47 µM). However, I3C in combination with gemcitabine exerted powerful anti-cancer effects. The IC50 with 200 µM I3C was 0.388 µM and 1.13 µM with 100 µM I3C, which were lower than that of doxorubicin. Gemcitabine is the current FDA approved single agent for first-line treatment for patients with stage II, III and metastatic adenocarcinoma of the pancreas. This study demonstrated the potential of I3C, a possible non-toxic hypomethylating agent, combined with the anti-cancer agent, gemcitabine, to be a powerful strategy for treating pancreatic cancer.

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 2556. doi:10.1158/1538-7445.AM2011-2556
Abstract 2582: P2X7 receptor is functional in myeloma cell lines and myeloma patient cells and can be modulated by P2X7 receptor antagonists: Implications for myeloma therapy
Authors: Donovan Kathleen A. , Moon-Tasson Laurie , Hromockyj Alexander E. , Meyer Debra M. , Lust John A.
Published: June 2012

Inflammation is a driving factor in the pathogenesis of many cancers including multiple myeloma. Myeloma is a plasma cell tumor whose early stages are characterized by cytokine dependent growth, predominantly driven by IL-6. We have demonstrated that IL-1β is a key inducer of IL-6 expressed by bone marrow stromal cells in a paracrine fashion. The P2X7 receptor (P2X7R) is an ATP-gated ion channel expressed by cells of the hematopoetic lineage that has been shown to play a critical role in IL-1β processing and secretion. We investigated the role this receptor may play in the IL-1/IL-6 cytokine pathway in multiple myeloma. A panel of multiple myeloma cell lines was evaluated by RT-PCR for the expression of P2X7R mRNA. Levels of expression in ANBL-6, MM1S, U266, RPMI-8226 and KAS-6/1 were comparable to U937, a previously characterized P2X7R positive cell line. A newly derived plasmacytoma cell line, PCYT3, showed very low levels of message expression. The ability of ATP to trigger the processing and release of IL-1β by activation of the P2X7 channel was studied using KAS-Pro, a myeloma cell line stably transfected with a pro- IL-1β gene. IL-1β, measured by ELISA, was released in a dose dependent fashion in response to increasing amounts of ATP ranging from 1mM to 5mM. Three P2X7R specific antagonists were tested for their effect on ATP stimulated IL- 1β release from KAS-Pro; all 3 compounds demonstrated inhibition in a dose dependent manner with varying degrees of potency correlating with P2X7R inhibition. In addition fresh patient samples (15 multiple myelomas/ 4 smoldering myelomas/8 MGUS) were evaluated for inhibition of IL-1β release by the P2X7R antagonists through direct measurement of IL-1β by ELISA as well as by an indirect measurement of IL-1β induced IL-6 production by normal bone marrow stromal cells. Greater than 90% inhibition of IL-1β release was demonstrated in all MM & SMM patients positive for IL-1β expression. IL-1β was not detected in any of the MGUS patients and therefore no affect of the inhibitors was observed. These results confirm the activity of functional P2X7 receptors on myeloma cell lines and in fresh patient samples and suggest a role for the use of P2X7 receptor antagonists in the therapy of myeloma.

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 2582. doi:10.1158/1538-7445.AM2011-2582
Abstract 2594: Ciclopirox inhibits lymphatic endothelial cell tube formation by suppressing VEGFR-3-mediated ERK signaling pathway
Authors: Luo Yan , Huang Shile
Published: June 2012

Ciclopirox olamine (CPX), an off-patent antifungal agent used to treat mycoses of skin and nails, has recently been demonstrated to be a potential anticancer agent. However, the underlying mechanism is not well understood. Here for the first time we show that CPX inhibited lymphangiogenesis in an in vitro model (tube formation). This effect was in part associated with inhibition of vascular endothelial growth factor receptor 3 (VEGFR-3) expression, as overexpression of VEGFR-3 conferred partial resistance to CPX inhibitory effect on tube formation in lymphatic endothelial cells (LECs), whereas downregulation of VEGFR-3 mimicked the effect of CPX, blocking the tube formation. Further study revealed that CPX did not alter mRNA level, but inhibited protein synthesis and promoted protein degradation of VEGFR-3. In addition, we found that CPX inhibited phosphorylation of the extracellular signal-related kinase 1/2 (ERK1/2), a downstream effector of VEGFR-3. Overexpression of VEGFR-3 attenuated CPX inhibition of ERK1/2 phosphorylation, whereas downregulation of VEGFR-3 inhibited extracellular signal-related kinase 1/2 (ERK1/2) phosphorylation in LECs. Ectopic expression of constitutively active mitogen -activated protein kinase kinase 1 (MKK1) resulted in activation of ERK1/2, and partially prevented CPX inhibition of LEC tube formation. The results suggest that CPX inhibits LEC tube formation at least in part through inhibiting VEGFR-3-mediated ERK signaling pathway.

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 2594. doi:10.1158/1538-7445.AM2011-2594
Abstract 2615: Antitumor activity of a dual PI3K and HDAC inhibitor in hematologic cancer models
Authors: Bao Rudi , Wang Dagong , Qu Hui , Yin Ling , Xu Guang-Xin , DellaRocca Steven , Borek Mylissa , Atoyan Ruzanna , Forrester Jeffrey , Samson Maria , Wang Jing , Zhai Hai-Xaio , Chan Mendy , Lai Cheng-Jung , Cai Xiong , Qian Changgeng
Published: June 2012

Recent evidence indicates that PI3K-Akt-mTOR signaling plays a crucial role in the development and progression of hematologic cancers. Therefore, inhibition of this pathway using isotype-selective or pan-PI3K inhibitors has recently been investigated extensively in hematologic malignancies. However, compensatory/feedback mechanisms in cancer cells may present a major challenge for these PI3K inhibitors. On the other hand, HDAC inhibitors, such as vorinostat and romidepsin, have been approved as a monotherapy for CTCL. Their efficacy as single agent or in combination with other approved therapeutics is being evaluated in multiple clinical trials for other types of hematologic cancers, including DLBCL, Hodgkin lymphoma, AML, ALL, CLL, and multiple myeloma. Based on the observation that synergic effects can be achieved by inhibition of both HDAC and PI3K in cancer cells as reported previously, we developed small-molecule compounds that are able to simultaneously inhibit both PI3K and HDAC. One of the lead compounds exhibits potent inhibition of all PI3K class I subtypes as well as HDAC. In cell growth inhibition assays, this compound displays potent activity in hematologic cancer cell lines, including leukemia, lymphoma, and myeloma. Besides PI3K-Akt-mTOR pathway suppression, this compound is able to up-regulate tumor suppressors p53 and p21 and simultaneously inhibit compensatory Ras-Raf-MEK signaling in cancer cells via epigenetic modifications by HDAC inhibition. In vivo experiments demonstrate this compound is orally bio-available with a long half-life in tumor tissues from xenograft models. Efficacy studies demonstrate this compound is able to inhibit tumor growth or induce tumor regression in animals implanted with various hematologic cancer cell lines. Furthermore, this compound induces apoptosis and inhibits cancer cell proliferation in these tumor xenografts. Favorable safety profile has been observed in early preclinical studies. Based on these results, this compound warrants further investigation.

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 2615. doi:10.1158/1538-7445.AM2011-2615