bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A59: Increased expression of ABC transporter genes in lung cancer CD133-positive cells
Authors: Gatti Laura , Cossa Giacomo , Bertolini Giulia , Tortoreto Monica , Tinelli Stella , Fontanella Enrico , Delia Domenico , Roz Luca , Sozzi Gabriella , Perego Paola 
Published: June 2012

Abstract
Drug resistance represents a major obstacle towards the cure of different tumor types including non-small cell lung cancer (NSCLC), being one of the main causes of failure of antitumor therapy. Tumor cells frequently exhibit simultaneous resistance to multiple structurally unrelated drugs, a phenotype known as multidrug resistance (MDR). A major cause of the MDR phenotype is the over-expression of members of a conserved family of transmembrane proteins (ABC transporters). Different structurally unrelated compounds, including conventional cytotoxic and target-specific agents are substrates for ABC transporters. Cancer stem cells (CSC) refer to a subset of tumor cells with the ability to self-renew and generate the diverse cells that comprise tumors. At present, the mechanisms contributing to the drug-resistant phenotype of CSC are poorly understood. Some lines of evidence support that specific ABC transporters may be expressed in CSC and may be relevant therapeutic targets. The aim of the present study was to examine the pattern of expression of ABC transporter genes in spheres derived from human lung tumors, which we found enriched for CD133 (prominin-1), a surface glycoprotein described as a marker of cancer-initiating cells in different tumor types. To better define the molecular features of cancer cells endowed with stem-like features with respect to cellular defence mechanisms, using TaqMan MicroFluidic cards we analyzed the mRNA levels of transporters of the ABC superfamily in CD133+ and CD133− cell populations sorted from lung tumor cell lines grown as spheres. With this approach, we found that around 70% of the 50 human ABC transporters were expressed at detectable levels in floating spheres obtained from human lung cancer A549 adherent cell line and in the corresponding sorted populations. When compared to the CD133− raction, CD133+ cells exhibited a marked increased expression of different components of the ABCC family which are known to be involved in the MDR phenotype (i.e., ABCC1). The level of ABCG2 mRNA was also enhanced. Similar results were obtained in CD133+ cells isolated from a cell line established from a human primary lung tumor growing as floating spheres. Thus, CD133+ cells expressed ABCG2 and additional ABC transporters that may contribute to determine a drug-resistant phenotype. A better knowledge of the pattern of expression of ABC transporters in lung cancer CD133+ cells may lead to develop approaches that will circumvent drug resistance in NSCLC and is expected to contribute to optimization of therapy, based on targeting of ABC transporters.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A59.
Abstract A62: A novel Eg5 inhibitor that causes mitotic arrest leading to rapid cancer cell death shows broad-spectrum antitumor activity in preclinical xenograft tumor models
Authors: Ye Xiang S. , Fan Li , Van Horn Robert , Yin Tinggui , Nakai Ryuichiro , Ohta Yoshihisa , Credille Kelly , Donoho Gregory , Akinaga Shiro , Murakata Chikara , Perkins Everett , Ocheltree Scott , Yamashita Yoshinori , Blanchard Kerry , Westin Eric 
Published: June 2012

Abstract
Antitubulin agents including taxanes and vincas that target mitosis of rapidly dividing cancer cells are among the most effective cancer therapies in current clinical use. However, these antitubulin agents also have debilitating side effects that are dose-limiting, such as neuropathy, due to their disruption of the normal microtubule functions in resting cells including neuronal cells. Eg5 is an evolutionarily conserved mitosis-specific kinesin essential for bipolar mitotic spindle formation and has no roles in microtubule functions of resting cells. Inactivation of Eg5 causes mitotic arrest of proliferating cells, resulting in formation of monopolar spindles. Targeting Eg5 for cancer treatment thus represents an attractive strategy that has the potential to maximize the anticancer efficacy by inhibiting cancer cell mitosis while minimizing debilitating side effects associated with antitubulins. Here we describe a selective ATP-non competitive small molecule inhibitor of human Eg5 kinesin. The Eg5 inhibitor shows no effects on microtubule dynamics in cell-free assays and arrests cells specifically at mitosis with monopolar spindles, resulting in rapid cancer cell death. Growth inhibition assays against a panel of 21 cancer cell lines shows that the Eg5 inhibitor has potent and broad-spectrum activity with IC50 values ranged from 0.55 nM to 14.2 nM. Quantitative live cell imaging and high content imaging reveal that the Eg5 inhibitor has a threshold concentration activity and kills cancer cells specifically at mitosis in a time/cell cycle, but not concentration above the threshold,-dependent manner. Consistent with the in vitro activities, the Eg5 inhibitor shows broad-spectrum antitumor activity in preclinical xenograft tumor models representing major human cancer histologies also including drug resistant tumors and demonstrates superiority as compared to several chemotherapeutic agents targeting G2/M. Furthermore, its in vivo antitumor activity is highly schedule-dependent with a clear threshold dose effect, as expected from in vitro observations. Indeed, the Eg5 inhibitor exhibits a robust PK/PD relationship in antitumor activity and its antitumor activity is associated with mitotic arrest of cancer cells and subsequent cell death. The Eg5 inhibitor is currently being evaluated in Phase I studies.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A62.
Abstract A67: Molecular evidence of increased antitumor activity of gemcitabine in combination with a Cdk inhibitor, P276 in pancreatic cancer
Authors: Joshi Kalpana S. , Rathos Maggie J. , Joshi Kavita , Khanwalkar Harshal , Sharma Somesh 
Published: June 2012

Abstract
Purpose: Gemcitabine is an inhibitor of ribonucleotide reductase and DNA synthesis and is a standard of care for the treatment of pancreatic cancer. The present study investigates whether the cdk inhibitor P276 would be synergistic with gemcitabine in pancreatic cancers.
Experimental design: Various pancreatic cancer cell lines were treated with gemcitabine and P276 and the cytotoxicity was assessed using the combination index. The effect of gemcitabine and P276 on cell cycle and apoptosis was analyzed by flow cytometry. Several genes that are known to inhibit apoptosis and contribute to chemoresistance were analyzed using western blot analysis and RT-PCR. Finally, in vivo efficacy of the combination was studied in Panc-1 xenograft model in SCID mice.
Results: The combination of gemcitabine followed by P276 was found to be synergistic in various pancreatic cancer cell lines Panc-1, Capan-1, BxPc-3, AsPc-1 and MiaPaca-2 as assessed by the combination index using the Compusyn software. Mechanistic studies indicated enhancement of apoptosis in Panc-1 cells as seen by flow cytometry and increase in the antiapoptotic Bcl-2 protein by western blot analysis. Several genes that are known to inhibit apoptosis and contribute to chemoresistance such as p8, cox-2 and survivin were assessed to investigate the basis for the observed chemosensitizing effects of P276. P276 potentiated the gemcitabine induced cytotoxicity by downregulation of p8, cox-2 and survivin. In contrast, cox-2 was found to be significantly up regulated when the cells were exposed to gemcitabine alone, while there was no effect on p8 or survivin as compared to control, suggesting the potential mechanism of acquired chemoresistance to gemcitabine. BNIP3 the tumor suppressor is also downregulated in most pancreatic cancer cell lines and is associated with chemoresistance to gemcitabine. Interestingly BNIP3 was significantly up regulated in the combination and P276 alone but not by gemcitabine alone. In addition to in vitro results, we show here that gemcitabine in combination with P276 is much more effective as an antitumor agent compared with either agent alone in our Panc-1 xenograft tumor model in SCID mice.
Conclusion: These data demonstrate that the gemcitabine and a Cdk inhibitor, P276 combination displays synergistic cytotoxic activity, induces apoptosis and sensitizes the pancreatic cells to gemcitabine by modulating the pro- and anti apoptotic proteins. In vivo evidence of the synergistic combination is also demonstrated in Panc-1 xenograft model. The chemosensitzation of pancreatic tumors to gemcitabine would likely be an important and novel strategy for treatment of pancreatic cancer and enable the use of lower and safer concentrations, to pave the way for a more effective treatment in this devastating disease.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A67.
Abstract A73: The Bcl-2/BclXL inhibitor, ABT263, enhances paclitaxel-induced apoptosis in NSCLC models
Authors: Belmont Lisa D. , Yue Peng , Tan Nguyen , Malek Mehnaz 
Published: June 2012

Abstract
The anti-apoptotic protein, BclXL, is thought to be an important chemo-resistance factor (Amundsen et al, 2000), and the combination of a BclXL inhibitor and paclitaxel exhibits increased NSCLC cancer cell killing in culture and in xenograft models (Shoemaker et al, 2006). ABT263 is a small molecule inhibitor of Bcl-2, BclXL and Bcl-w, that is currently in clinical trials (Tse et al, 2008). We set out to address the following questions 1) is ABT-263 broadly synergistic with paclitaxel in NSCLC cells, 2) what is the mechanism of the synergistic interaction and 3) can we identify biomarkers to guide the selection of patients that are likely to respond to the combination of ABT263 and taxane based chemotherapy regimens? We screened a panel of 26 NSCLC cell lines for synergy with ABT263. All 26 cell lines exhibited a synergistic response to the combination, as evaluated by Bliss additivity, and 20 cell lines had Bliss sum values in excess of 100, considered to be a robust synergy response in this assay. In order to address the mechanism of synergy, we performed time-lapse microscopy on GFP-H2b expressing A549 cells. We find that the addition of ABT263 alters the timing and fate of cells that enter mitosis in the presence of paclitaxel. Paclitaxel alone caused prolonged mitotic arrest usually followed by mitotic slippage. ABT263 as a single agent had little effect on mitosis, but caused cells to die rapidly from a mitotic arrest state when added to paclitaxel. This resulted in an increase in the rate and percentage of cell death compared to either single agent. To identify biomarkers that might influence synergy between ABT263 and paclitaxel, we identified genes whose mRNA levels had significant correlations with the Bliss score. Together these data suggest that the combination of ABT263 and paclitaxel has the potential to have improved efficacy in cancers that are refractory to paclitaxel.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A73.
Abstract A78: Role of PTEN and ionizing radiation in underpinning differential activation of interleukin-8 in prostate cancer cells
Authors: Berlingeri Silvia , Gallagher Rebecca , Maxwell Pamela , O'Sullivan Joe , Waugh David 
Published: June 2012

Abstract
Prostate cancer (CaP) cells exhibit varying sensitivity to radiotherapy. Previous studies of our group showed that the synthesis of the CXC-chemokine Interleukin-8 (CXCL8) is linked to resistance of cancer cells to environmental and chemical stresses. Accordingly, we wished to explore the impact of ionizing radiation in modulating Interleukin-8 expression in Prostate Cancer cells (PC) in vitro. IR (3Gy) induced rapid time-dependent, NF¡B transcriptional activity in PC3 and LNCaP cells that co-incided with the detection of increased mRNA transcript levels for CXCL8 in both cell lines. However, although a same rapid increase in IL-8 mRNA was observed in Du145 and 22Rv1 cells, they show a more pronounced AP-1 activation, suggesting that in this prostate cancer cell lines signalling cascade to IL-8 mRNA synthesis is mainly driven by AP-1. Immunoblotting also confirmed that expression of CXCL8 increased rapidly in PC3 and LNCaP cells in response to IR (30 min to 2 hours). Subsequently, we investigated the importance of the tumor suppressor gene Phosphate and Tensin Homolog (PTEN) in underpinning this differential response of PC3 and LNCaP (PTEN-null) compared to Du145 and 22Rv1 (PTEN-wt) cells to IR. Moreover we sought to clarify the link between the PTEN-status in our in vitro model and the activation of PI3K, MAPKs and PKC pro-survival pathways after exposure of cells to Ionizing Radiation. Accordingly, we will continue to explore our hypothesis that PTEN acts as a master regulator of radiosensitivity in CaP cells by activating signal transduction pathways in irradiated cells.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A78.
Abstract A81: Synergistic antitumor efficacy of the multikinase inhibitor, sorafenib and paclitaxel combination in NSCLC tumor model
Authors: Jeon Eun Kyoung , Zhang Xiang-Hua , Shin Jung-Young , Yoon Seong-Ae , Kang Jin-Hyoung 
Published: June 2012

Abstract
Background: Sorafenib (BAY 43-9006) is a multi-kinase inhibitor that targets a serine-threonine kinase, B-Raf as well as several tyrosine kinases. Given the numerous molecular targets of sorafenib, several potential mechanisms of its inhibitory activity on tumor cell proliferation, angiogenesis and anti-apoptosis have been proposed. Paclitaxel exhibits unique and potent anti-cancer activity in the treatment of non-small cell lung cancer (NSCLC). Our aim of this study, is to examine the anti-proliferative, anti-angiogenesis effect and apoptosis induction when sorafenib combined with paclitaxel in NSCLC tumor model.
Methods: We investigated sorafenib's effect on cell proliferation, cell cycle distribution, ERK phosphorylation in A549 NSCLC cell line using SRB assay, flow cytometry, and Western blot analysis, respectively. In vivo, A549 tumor cells were implanted in the Balb/c nu/nu mice. Five different combination schedules of sorafenib and paclitaxel were applied with their single treatment. PPS and PSS combination therapy. Tumor volume and body weight was measured at two times per week. Intratumoral molecular changes were studied on paraffin-embedded tumor tissue block from xenograft mice using immunohistochemistry and the apoptotic change was measured with TUNEL assay.
Result: In vitro study, single treatment of sorafenib or paclitaxel inhibited cell proliferation in A549 cells with dose-dependent manner. Sorafenib effectively inhibited the phosphorylation of ERK and induced G0/G1 arrest of cell cycle. When these two agents were combined with different schedules, schedule-dependent cytotoxicity and cell cycle arrest were observed. In A549 xenograft model, combination of sorafenib and paclitaxel more significantly suppressed tumor growth than their single treatment. However, PSS combination caused profound body weight loss compared with other treatment schedules. In immunohistochemistry study, greater inhibition of Ki-67 as well as pAKT and pERK, and CD31 were observed in PPS combination compared with single treatment. In TUNEL assay, significant apoptosis was observed in combination treatment.
Conclusion: Taken together, sorafenib, paclitaxel, and their combination effectivity inhibited tumor growth and angiogenesis via down regulation of pAKT and pERK signaling and apoptosis induction in NSCLC tumor model. The PPS and PSS combination schedule demonstrated more potent antitumor activity including anti-proliferation, anti-angiogenesis, and apoptosis compared to other combination schedules.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A81.
Abstract A91: Identification of nuclear hormone receptors critical for rexiniod-mediated growth suppression of normal human breast cells
Authors: Rodenberg Jennifer M. , Uray Ivan P. , Bissonnette Reid P. , Brown Powel H. 
Published: June 2012

Abstract
Background: Drugs targeting estrogen signaling or production have successfully prevented or treated estrogen receptor-positive breast cancers, but not estrogen receptor-negative (ER-negative) breast cancers. Our laboratory has demonstrated that rexinoids prevent ER-negative breast cancer in transgenic mice by 90% at high-doses. Since the prevention is not 100% effective, it is imperative to develop more efficacious prevention strategies by determining the mechanism of rexinoids. We hypothesized that rexinoids are specifically able to prevent breast cancer by suppressing growth though interactions with key nuclear hormone receptors. To test this hypothesis we conducted high-throughput screens to determine which nuclear hormone receptors are critical to the growth suppressive effects of rexinoids.
Methods: We used quantitative RT-PCR to determine the quantity of mRNA transcripts for all 48 nuclear hormone receptors in human mammary epithelial cells (HMECs). To identify nuclear hormone receptors that when knocked-down reverse the effects of rexiniod treatment, a final concentration of 30nM of pools of three independent siRNAs specific to each nuclear hormone receptor was used. High-throughput microscopy of the siRNA-treated HMECs stained with DAPI (1ug/mL) and EdU (10mM) was used to analyze cell number and percent S-phase. Those nuclear receptors whose corresponding siRNA reversed the growth inhibitory effects of the rexinoid 75% or greater, were considered for further investigation. Co-immunoprecipitation (coIP) and GST pull-down assays are being conducted to investigate whether the identified nuclear hormone receptors form a complex with RXR proteins.
Results: qRT-PCR analysis confirmed that many of known RXR-binding nuclear hormone receptors are expressed in HMECs. High-throughput screens indicate that knockdown of most receptors alone affect growth of HMECs, but do not reverse the effects of rexinoid treatment. Receptors that did reverse the growth suppressive effect of rexiniods include RXRα, VDR, PNR and PPARγ. Currently, we are further investigating the function of these receptors in HMECs and other normal, premalignant, and malignant breast cells.
Conclusions: These experiments identified nuclear hormone receptors that are critical for the growth suppressive effects of rexinoids in normal human breast cells. Such studies identify possible targets for preventative therapy, alone or in combination with rexinoids to increase the efficacy of drugs for more effective prevention of estrogen receptor-negative breast cancer. Support: NCI R01 CA78480 (PHB, IPU) and NIH/NCI T32 CA90221 (JMR)
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A91.
Abstract A95: Epigenetic changes in colon cancer cell lines treated with the green tea polyphenolic, EGCG
Authors: Brown Vondina R. , Morris Jay , Wargovich Michael J. 
Published: June 2012

Abstract
Retinoids are known for their role in regulating cell growth and proliferation and for activating tumor suppressor genes. We have previously shown that Retinoid X Receptor alpha (RXRα) is silenced in tumors of the colon cancer AOM-APCMin/+ mouse model. Upon treatment with green tea, RXR expression was restored and intestinal tumorigenesis was inhibited. We hypothesize that tea polyphenols, especially epigallocatechin gallate (EGCG), induce modification of gene expression through effects of DNA methyltransferases (DNMTs) as well as Histone Deacetylases (HDACs). We treated HT-29 and HCT116 colon cancer cells with EGCG concentrations of 0, 50, 100 or 150µM or 5µM of the DNMT inhibitor 5-aza-2dC for 48, 72 and 96 hours as well as for two, three and four doubling times. The cell lines were chosen based on their methylation status. HCT116 cells are more sensitive to promoter region methylation compared to HT-29 cells. Using nuclear fractions of the cell lysates, we probed for presence of the most common DNMTs and HDACs using western blotting. We found that expression of DNMTs as well as HDACs was inhibited in a dose dependent manner following treatment with EGCG. We also found that treatments according to doubling times showed a more profound difference in expression levels when compared to traditional time points. We can conclude that the silencing of RXRα may be due in part to by repressing effects of EGCG on DNMT as well as HDAC activity. This could be one potential mechanism of cancer chemoprevention in green tea that outlines a new epigenetic pathway.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A95.
Abstract A96: Melanoma chemoprevention using topical PBISe
Authors: Chung Chinying , Madhunapantula SubbaRao V. , Meyers Craig , Desai Dhimant , Amin Shantu , Robertson Gavin P. 
Published: June 2012

Abstract
Despite public awareness and availability of sunscreen, incidence and mortality rates for malignant melanoma continue to increase every year. Novel strategies are required to prevent melanoma development as the causes for ∼60% of cases remaining unknown. While sunscreen is effective at protecting skin from UV radiation induced damage, inhibiting melanocytic lesion development using body creams or sunscreens containing chemopreventive agents could be a novel approach to fight this disease. Hence, the chemopreventive efficacy of PBISe, a selenium containing isosteric analogue of PBIT, has been examined in laboratory generated skin reconstructs and melanoma tumor xenograft models. The data demonstrate that PBISe treated skin reconstructs containing melanocytic lesion cells had 60–70% smaller tumor lesions compared to control treated skins. Furthermore, mice topically treated with PBISe had ∼50% fewer tumors compared to PBIT or acetone vehicle treated control groups. Mechanistically, PBISe elevated MAP kinase pathway activity as indicated by increased pErk1/2 levels to amounts that induced cellular senescence. Furthermore, PBISe treatment down-regulated cyclin-D1, upregulated the expression of cell cycle inhibitors p21 and p27 as well as apoptotic markers cleaved caspase-3 and PARP to inhibit cell proliferation and induce apoptosis. In conclusion, the results demonstrate the potential utility of topical PBISe application for preventing melanoma leision development.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A96.