bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 4450: A new paradigm for AS1411 activity: Uptake by macropinocytosis and induction of macropinocytosis by a nucleolin-dependent mechanism
Authors: Reyes-Reyes Elsa M. , Bates Paula J. 
Published: February 2011

Abstract
AS1411 is an experimental drug that is currently in Phase II clinical trials as a novel therapy for cancer. It is a G-rich phosphodiester oligodeoxynucleotide, which forms a stable quadruplex structure and binds specifically to nucleolin as an aptamer. We have shown previously that AS1411 can efficiently inhibit proliferation and induce cell death in many types of cancer cells, but has little effect on normal cells. Here, we report on the uptake of fluorescently labeled AS1411 (FL-AS1411) in a variety of cancer cell lines (sensitive to AS1411) and non-malignant cells (resistant to AS1411), which we studied using flow cytometry and confocal microscopy. In both cancer and non-malignant cells, uptake of FL-AS1411 was much higher that that of an inactive control oligonucleotide and was rapid (clearly visible in cytoplasmic foci by 15 min). Uptake of FL-AS1411 (evaluated at 2 h) was independent of the presence of serum, but strongly temperature-dependent, indicating an active process. In cancer cells, FL-AS1411 uptake was significantly suppressed by macropinocytosis inhibitor, amiloride, but not by dynamin inhibitor, dynasore, and confocal microscopy showed that AS1411 co-localized mainly with the macropinocytic tracker, dextran, but not with transferrin (a marker of receptor-mediated endocytosis). In contrast, in non-malignant cells, FL-AS1411 uptake was significantly suppressed by dynasore, but not by amiloride. These results suggest that the major mechanism of internalization of AS1411 occurs via macropinocytosis in cancer cells, but via clathrin-dependent and/or caveolae-dependent pathways in normal cells. Additionally, we found that treatment of cancer cells with an oligonucleotide containing the AS1411 sequence caused hyperstimulation of macropinocytosis, provoking an increment in its own uptake. No stimulation of macropinocytosis was observed in non-malignant cells, which are insensitive to AS1411. By using siRNA approaches, we showed that nucleolin is not required for the initial phase of FL-AS1411 uptake (at 2 h), but it is necessary for the induced macropinocytosis and consequently for the second phase of FL-AS1411 uptake (at 24 h). These data confirm the important role of nucleolin in mediating the activity of AS1411 and provide a new model for the mechanism of action of AS1411 in cancer cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4450.
Abstract 4458: Antiproliferative effects of γ-tocotrienol are mediated by suppression in the activation of Met tyrosine kinase receptors in neoplastic +SA mammary epithelial cells
Authors: Bachawal Sunitha V. , Wali Vikram B. , Sylvester Paul W. 
Published: February 2011

Abstract
γ-Tocotrienol, a member of vitamin E family of compounds, displays potent anticancer activity against breast and other types of cancers. Previous studies have shown that the antiproliferative effects of γ-tocotrienol are associated with the suppression in the epidermal growth factor (EGF)-dependent phosphatidylinositol-3-kinase (PI3K)-dependent kinase-1 (PDK-1) and Akt phosphorylation in neoplastic +SA mammary epithelial cells. Also, studies showed that γ-tocotrienol treatment had no direct effect on Akt activity and did not alter the relative intracellular levels of PI3K, indicating that γ-tocotrienol might act upstream of the PI3K/PDK-1/Akt pathways at the level of membrane tyrosine kinase receptors in +SA mammary tumor cells. Since aberrant activation of the Met tyrosine kinase receptors is observed in various types of cancers and is associated with poor prognosis, studies were conducted to determine the effect of γ-tocotrienol on EGF and hepatocyte growth factor (HGF)-dependent activation of Met tyrosine kinase receptors in +SA mammary tumor cells. Treatment with serum-free media containing various doses of EGF (1-10 ng/ml) or HGF (1-10 ng/ml) significantly increased the growth of +SA mammary tumor cells as compared to serum-free control group over a 3-day culture period. Stimulation of +SA cells with EGF (10 ng/ml) or HGF (10 ng/ml) resulted in the activation of Met tyrosine kinase receptors. Treatment with Met tyrosine kinase inhibitor, SU11274 (5.5 μM) or γ-tocotrienol (4 μM) inhibited the EGF or HGF-dependent growth and activation of Met receptors in +SA mammary tumor cells after a 3-day culture period. Also, knockdown of Met receptors using Met specific siRNA decreased the expression of Met receptors and significantly inhibited the EGF or HGF-dependent growth of +SA cells. Additional studies showed that when +SA cells were simultaneously exposed to EGF (10 ng/ml) and HGF (10 ng/ml), the growth inhibitory effects of γ-tocotrienol (4 μM) and SU11274 (5.5 μM) were significantly reversed, associated with the activation of Met receptors. However, combined treatment with low doses of γ-tocotrienol (2 μM) and SU11274 (3 μM) inhibited the EGF and/or HGF-dependent growth of neoplastic +SA mammary epithelial cells. These results strongly suggest that γ-tocotrienol treatment may provide significant health benefit in the prevention and/or treatment of breast cancer in women with deregulated HGF/Met signaling. Supported by grants from NIH (CA86833) and First Tech International Ltd.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4458.
Abstract 4461: Involvement of cleaved p73 isoforms in anoikis
Authors: Alsafadi Samar , Tourpin Sophie , Benihoud Karim , André Fabrice , Vassal Gilles , Ahomadegbe Jean Charles 
Published: February 2011

Abstract
p73, a p53 family member, is a transcription factor that plays an important role in cell cycle control, differentiation and apoptosis. p73 has been shown to be capable of replacing p53, inducing apoptosis in p53-deficient cells. In this study, we tried to determine the role of p73 in anoikis, a type of apoptosis induced by inadequate cell-matrix interaction. Six breast cancer cell lines with different p53 status were treated with doxorubicin (DOX) and anoikis was analyzed 48 hours after treatment. We found that, independently of the p53 status, DOX-induced anoikis was associated with p73 cleavage and the activation of caspases. p73 cleavage was not triggered in caspase-3-null MCF-7 breast cancer cell line. To confirm the implication of p73 cleavage in anoikis, we transfected breast cancer cell lines with plasmids bearing TAp73α, TAp73β or ΔNp73α. The overexpression of p73 isoforms in transfected cells induced detachment of these cells from the culture flask. Anoikis in these cells was associated with cleavage of the transfected isoform of p73. Once again, p73 cleavage was not detected in caspase-3-null MCF-7 cell line confirming the involvement of caspase 3 in p73 cleavage. The use of flag antibody, which recognizes the N-terminus of transfected proteins, and p73 antibodies, which recognize the C-terminus of these proteins, enabled us to demonstrate that there are two possible cleavage sites in TAp73α generating two different cleaved forms. However, when cells were transfected with TAp73β or ΔNp73α, only one cleaved form was generated. TAp73β probably harbors a N-terminal site, while ΔNp73α only harbors a C-terminal site. Cleavage at the N-terminal site, rather than that at the C-terminal site, appears to be important for an efficient apoptotic response, because it is associated with stabilization of cleaved proteins and high toxicity.
Further studies are warranted to determine the accurate role of p73 cleavage in anoikis, especially since these cleavages arise independently of the p53 status and therefore could contribute to response to stress in cells with non functional p53.
Acknowledgements: this work is supported by “La Ligue contre le cancer - Comité de la Somme” and the Syrian Ministry of Health.
Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4461.
Abstract 4464: C-erbB3 protein modifications are secondary to severe cell membrane alterations induced by Irvalec treatment in CHO cells
Authors: Váradi Tímea , Guijarro José Manuel Molina , Vereb György , Galmarini Carlos M. , Szöllõsi János , Nagy Peter 
Published: February 2011

Abstract
Irvalec® is a marine-derived antitumor agent that is currently undergoing phase II clinical trials. The compound induces a necrotic cell death associated with the appearance of membrane blebs and severe cell swelling reflecting a serious membrane damage caused by the drug. Indirect evidence has also suggested a possible role of ErbB proteins, in particular ErbB3, and lipid rafts in conferring sensitivity to Irvalec treatment. In order to assess the role of ErbB protein expression in the mechanism of action of Irvalec, and to measure the effect of drug treatment on the clustering properties of these proteins, we generated CHO cell lines stably transfected with ErbB2 (CHO-ErbB2) or with ErbB2 and ErbB3 (CHO-ErbB2-3). The IC50 values of the three cell lines for Irvalec did not differ significantly from each other. On the other hand treatment with Irvalec induced a significant increase in the binding of a conformational sensitive antibody to ErbB3 (ErbB3.105.5) without modifying the binding of other ErbB3 antibodies or antibodies against ErbB2. In addition, Irvalec treatment decreased the homoassociation of ErbB2 and ErbB3 measured by flow cytometric FRET. A431 cells transfected with GPI-anchored GFP or ErbB3-citrine showed significant Irvalec-induced patching of the GPI-anchor and ErbB3, whereas the distribution of ErbB1 and ErbB2 were not affected in cells transfected with ErbB1-GFP or ErbB2-mYFP. In conclusion, our data do not support a role for ErbB proteins in determining sensitivity to Irvalec, but show that these receptors are indirectly affected by exposing cells to the compound. These alterations should be ascribed to cell membrane modifications induced by Irvalec treatment
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4464.
Abstract 447: Hypoxia upregulates Nodal expression via the HIF-1 pathway in poorly metastatic breast cancer cells
Authors: Taylor Meghan J. , Postovit Lynne-Marie 
Published: February 2011

Abstract
Low tumour oxygen levels (hypoxia) are associated with a poor clinical prognosis for breast cancer patients. The acquisition of a plastic, stem cell-like phenotype is similarly associated with resistance to therapy and increased metastatic potential. Recent studies have demonstrated that metastatic breast cancer cells express the embryonic stem cell factor Nodal, and that the expression of this protein is correlated with breast cancer progression. Our research establishes that hypoxia induces Nodal expression in poorly metastatic breast cancer cells. The effects of hypoxia on Nodal expression in poorly metastatic MCF-7 and T47D breast cancer cells, which do not endogenously express Nodal, were examined by exposing cells to decreasing concentrations of oxygen (20%-0.5%) for varying amounts of time (0 h - 48 h). Additionally, reoxygenation experiments were performed by exposing cells to 0.5% oxygen for 24 h and restoring them to 20% oxygen for 0 h - 6 days. Time course and dose response experiments determined that T47D cells exposed to 0.5% oxygen for 48 hours saw a maximal (1.5 fold) induction of Nodal mRNA expression and marked increase in protein levels. This expression persisted for up to 6 days with reoxygenation at 20% oxygen. The molecular mechanism underlying the hypoxic induction of Nodal expression was examined by investigating the role of the HIF-1 pathway. HIF-1α expression was knocked down with siRNA and cells exposed to 0.5% oxygen, and conversely, HIF-1α was over-expressed and cells exposed to 20% oxygen. The HIF-1α-specific siRNA returned Nodal expression to control levels in hypoxia and over-expression of HIF-1α elicited an upregulation of Nodal expression in normoxic conditions. This work reveals a mechanism by which a normally stem cell-associated factor can be upregulated by hypoxia in poorly metastatic breast cancer cells. Furthermore, it provides additional insight into the oxygen-mediated regulation of cancer cell plasticity and metastatic potential.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 447.
Abstract 448: Elevated co-expression of HIF-1α and GLUT-1 is associated with poor prognosis for oral squamous cell carcinoma patients
Authors: Eckert Alexander W. , Lautner Matthias HW , Schütze Andreas , Schubert Johannes , Bilkenroth Udo , Taubert Helge 
Published: February 2011

Abstract
HIF1α is the key transcriptional regulator of the response to hypoxia in tumors. GLUT-1 is a HIF1α-dependent target gene that is upregulated under hypoxic conditions and enables glucose transport into tumor cells. We sought to identify if co-expression of both of these hypoxia-related proteins, as detected by immunohistochemistry, had prognostic relevance in oral squamous cell carcinomas [OSCC]. Eighty-two OSCC tumor samples were analyzed for their expression levels of both HIF1α and GLUT-1 by immunohistochemistry. Protein expression was assessed using an immunoreactive score system (IRS) and the correlation between gene expression and both clinical and pathohistological parameters were examined. Overexpression of either GLUT-1 or HIF1α was associated with poor overall survival in OSCC patients. Multivariate Cox's proportional-hazards regression analysis (adjusted for tumor size and tumor grade) revealed that moderate expression of GLUT-1 or HIF1α was significantly associated with overall survival (RR=5.07, p=0.002 and RR=4.5, p=0.017, respectively) as compared to the groups with low levels of expression of GLUT-1 or HIF1α. Co-expression of both HIF1α and GLUT-1 were additively and significantly associated with adverse prognoses in patients with OSCC. Patients whose tumors had high levels of expression of both HIF1α and GLUT-1 were found to have a 10.2-fold increased risk of tumor-related death (p=0.001) in the multivariate Cox's proportional-hazards regression analysis. Co-expression of high levels of HIF1α and GLUT-1 is significantly correlated with prognosis in OSCC patients, suggesting that the co-expression of these proteins can be used as both an early diagnostic and independent prognostic marker.
Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 448.
Abstract 4480: Preclinical evaluation of the mTOR inhibitor, temsirolimus, in combination with the epothilone B analog, ixabepilone
Authors: Menefee Michael E. , Bible Keith C. , Roemeling Christina Von , Copland John Al 
Published: February 2011

Abstract
Introduction: Despite significant progress over the last decade in the development of therapeutics for metastatic cancers including breast cancer (MBC), non small cell lung cancer (NSCLC), and renal cell carcinoma (RCC), most patients will ultimately succumb to their malignancy; more effective therapeutics are sorely needed. The microtubule (MT) is a well-validated target for anti-cancer therapeutics. Ixabepilone (Ixa), a MT stabilizer is approved for MBC and has demonstrated efficacy against other solid tumors. mTOR is another validated target for anti-cancer therapeutics. Temsirolimus (Tem) inhibits mTOR and is approved for advanced RCC. We tested the hypothesis that the addition of Ixa to Tem might augment its anti-tumor activity in vitro. Methods: The cell lines, A498 (RCC), MDA-MB-231 (MBC), and A549 (NSCLC) were treated with Tem alone, Ixa alone, or the combination. All cell lines were also treated with the combination of Tem and Ixa in a fixed ratio of 1:20; Tem doses ranged from 0.125 [nM] to 5 [nM] and Ixa doses ranged from 2.5 [nM] to 100 [nM]. The effects of the treatments were evaluated with clonogenic assays. Synergism was evaluated using CalucSyn 2.0 in accord with the isobologram method of Chou and Talalay. Results: Both Tem and Ixa inhibited cell growth in all tested cell lines as single agents in dose-dependent fashions. Moreover, the combination of Tem and Ixa synergistically enhanced cytotoxicity in all tested lines (see table below).Cell LineED50 [nM]CI (lowest value)A4980.449280.404A5490.285440.263MDA-MB-2310.483550.373
Conclusion: The combination of Ixa and Tem displayed promising activity in all tested cell lines. These findings support the further evaluation of this combination in a phase I clinical trial.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4480.
Abstract 4482: Novel and selective small molecule inhibitors of 3-phosphoinositide-dependent kinase-1 inhibit the PDK-1/AKT signaling pathway and cell proliferation
Authors: Baxi Sangita M. , Engstrom Lars , Walls Marlena , Marx Matthew A. , Murphy Sean , Ermolieff Jacques , Lingardo Laura , Lam Hieu , Zou Aihua , Alton Gordon , Smeal Tod , Yin Min-Jean 
Published: February 2011

Abstract
Receptor tyrosine kinases (RTKs), PTEN (phosphatase and tensin homolog deleted on chromosome 10), and PIK3CA (encodes the p110α subunit of phosphatidylinositol 3-kinase [PI3K]) frequently contribute to tumor progression through their ability to regulate the intracellular level of phosphatidylinositol-3,4,5-triphosphate (PIP3). 3-phosphoinositide-dependent kinase-1 (PDK-1), a serine/threonine kinase, activates the catalytic domain of numerous kinases by phosphorylating their T-loop sites. PDK-1 activity is required for activation of AKT, p70S6K, and RSK which lead to cell proliferation and transformation. The interaction of the pleckstrin homology (PH) domain of AKT with the membrane bound PIP3 confers a conformational change in AKT, allowing PDK-1 to phosphorylate AKT at the residue threonine-308 (T308). This T-loop activation at T308, along with the phosphorylation of the serine-473 residue by mTOR, fully activates the AKT pathway. Although the roles of many PDK-1 substrates have yet to be characterized, the oncogenic activity of aberrant PI3K pathway signaling through PDK-1 has been extensively validated. We have developed a series of 3-Carbonyl-4-Amino-Pyrrolopyrimidne (CAP) compounds that are potent inhibitors of human PDK-1 (full length and kinase domain) which demonstrate more than 100-fold selectivity against P70S6K, PI3K, AKT, and mTOR. In this study, representative compounds from the CAP series were used to perform a variety of anti-tumor assays. We demonstrate PDK-1 compounds inhibit the phosphorylation of T308 on AKT as well as downstream molecules of the PI3K pathway, such as S6 ribosomal protein (S6RP) in breast, lung and colon cancer cell lines harboring a PI3KCA mutation. Additionally, blockade of AKT and molecules in the PI3K pathway leads to the inhibition of cell proliferation and cell transformation in cancer cells. Our data suggest that the inhibition of PDK-1 activity is sufficient to induce anti-tumor activity in cancer cells through the PI3K-PDK1-AKT axis, and that a potent and specific PDK-1 inhibitor could potentially be developed as a therapeutic agent against several cancer types.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4482.
Abstract 4487: OSI-027, a potent and selective small molecule mTORC1/mTORC2 kinase inhibitor is mechanistically distinct from rapamycin
Authors: Bhagwat Shripad V. , Crew Andrew P. , Gokhale Praful C. , Yao Yan , Kahler Jennifer , Epstein David M. , Wild Robert , Pachter Jonathan A. 
Published: February 2011

Abstract
The PI3K/AKT/mTOR pathway is frequently activated in many human cancers and mTOR has been clinically validated as an effective anti-cancer target by rapamycin analogs such as CCI-779, RAD001 and AP23573. We discovered OSI-027, a potent and selective small molecule mTOR kinase inhibitor that inhibits both mTORC1 and mTORC2 unlike rapamycin and its analogs that inhibit only mTORC1. We profiled several human cancer cell lines to compare the mechanistic and functional effects of rapamycin and OSI-027. Rapamycin completely inhibited phosphorylation of S6 (surrogate for S6K1) and only partially inhibited phosphorylation of 4E-BP1 while OSI-027 completely inhibited phosphorylation of both S6 and 4E-BP1. Furthermore, rapamycin only decreased phosphorylation of AKT (S473) in 13% of cell lines and increased phosphorylation of AKT (S473) in 62% of cell lines after 24h treatment. In contrast, OSI-027 significantly reduced phospho-AKT (S473) in all cell lines tested. OSI-027 showed broad-spectrum anti-proliferative activity against both rapamycin-sensitive and -insensitive cell lines. Rapamycin only induced apoptosis in a small subset of tumor cell lines whereas OSI-027 induced apoptosis in the majority of tumor cell lines tested. These in vitro advantages of OSI-027 relative to rapamycin translated to greater tumor growth inhibition in xenograft models in vivo. These results demonstrate that OSI-027, a dual mTORC1/mTORC2 kinase inhibitor provides superior activity across a broad range of preclinical cancer models compared to rapamycin. Accordingly, OSI-027 has been advanced into Phase I clinical trials.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4487.