bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B262: Tyrosine kinase inhibitors induce rapid cellular alterations in breast cancer cells in vitro
Authors: Silvia Carloni , Fabbri Francesco , Brigliadori Giovanni , Ulivi Paola , Amadori Dino , Silvestrini Rosella , Zoli Wainer 
Published: June 2012

Abstract
Purpose: Alterations in tyrosine kinase (TK) expression or functionality have been linked to tumor growth, and the unraveling of TK pathways has led to the discovery of novel anticancer drugs. The aims of this study were to evaluate cytotoxic and multidrug resistance mechanisms, such as Ca2+ homeostasis and efflux pump activity, of three tyrosine kinase inhibitors (TKIs), lapatinib, sorafenib and gefitinib, in two breast cancer cell lines.
Methods: Two human breast cancer cell lines, Estrogen Receptor (ER) positive MCF-7 and ER negative BRC-230 were exposed to the investigated drugs for 20, 40, 60, 120 and 240 min. Cytotoxicity, cytosolic Ca2+ levels, extrusion pump activity and mitochondrial membrane depolarization were assessed by flow cytometry. Expression of drug efflux genes was determined by RT-PCR, and protein expression of drug targets by Western blot.
Results: MCF-7 cells did not express EGFR, p-EGFR, Her-2 or p-Her-2, while BRC-230 were positive for EGFR and p-EGFR only. ERK1/2 was equally expressed in both cell lines, but only BRC-230 were positive for p-ERK1/2. MEK and p-MEK were expressed in both cell lines, albeit more intensively in BRC-230. As expected, based on their drug target expression profiles, gefitinib and lapatinib were found to induce cytocidal effects and mitochondrial membrane depolarization in BRC-230 only, while sorafenib caused apoptosis and loss of mitochondrial potential in both cell lines. All three drugs triggered a rapid and biphasic increase in cytosolic [Ca2+] (after a 20 min exposure), and a decline in xenobiotic extrusion pump activity that was independent of efflux gene downregulation. The thapsigargin-induced depletion of endoplasmic reticulum Ca2+ blocked the increase in cytosolic Ca2+, but had no effect on multidrug transporter activity or on mitochondrial membrane depolarization.
Conclusions: Gefitinib, lapatinib and sorafenib induced a rapid increase in cytosolic [Ca2+] and mitochondrial membrane depolarization, in addition to blocking drug transporter activity, independently of the expression of specific drug targets and of drug-induced cytotoxicity. These data suggest that TKIs may elicit different molecular mechanisms to those previously reported in the literature. Further research of these pathways is warranted in order to identify new, more effective strategies for cancer treatment.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B262.
Abstract B264: IC261 induces cell cycle arrest and apoptosis of human cancer cells via a CK1δ/ε independent mechanism
Authors: Cheong Jit Kong , Virshup David M. 
Published: June 2012

Abstract
Casein kinase 1 delta (CK1δ) and CK1 epsilon (CK1ε) regulate Wnt/β catenin signaling and their dysregulation has been implicated in a variety of human cancers. Kinome RNAi screens and as well as targeted studies have identified CK1δ and CK1ε as prosurvival factors in a variety of cancer cell lines. While RNAi knockdown of CK1δ or CK1ε displayed only modest growth inhibition of various cell lines, the CKIδ/ε selective inhibitor 3-[2,4,6-(trimethoxyphenyl) methylidenyl]-indolin-2-one (IC261)(with an IC50 in the 20–50 µM range) has proven even more effective at selective killing of cancer cells, even at submicromolar levels. This finding has been taken as supportive evidence for the role of CKIε and CKIδ in cancer. The recent development of a selective and nanomolar CKIδ/ε inhibitor, PF670462, affords an opportunity to further explore this hypothesis. We found that PF670462 effectively blocked CK1 kinase activity and suppressed Wnt/β-catenin signaling in both HEK293 cells and HT1080 fibrosarcoma cells at submicromolar concentrations. However, consistent with the results of siRNA knockdown of CK1ε, PF670462 failed to induce cancer cell death at these concentrations. In contrast, we found that while 100 nM IC261 did not inhibit of CK1ε activity nor block Wnt/ catenin signaling in vivo, it resulted in the rapid induction of G2/M arrest of cell cycle and apoptosis in human cancer, but not non-transformed, cells. Taken together, inactivation of CK1δ/ε and subsequent block of Wnt/β catenin signaling may not be sufficient to inhibit cancer cell survival. Furthermore, IC261 potently regulates additional cancer cell targets at concentrations much lower than that required for CK1 inhibition and these novel unknown targets appear to be important for the maintenance of human cancer cell survival. Identification of the IC261 targets may provide insights into the mechanism of selective cancer cell toxicity.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B264.
Abstract B267: AR-mTOR-1: A potent, selective mTORC 1/2 kinase inhibitor for the treatment of malignancy
Authors: Wallace Eli M. , Xu Rui , Josey John , Gross Stefan D. , DeMeese Lisa , Fischer John , Miknis Greg , Humphries Mike , Regal Kelly , Fell Brad , Burkard Michael , DeWolf Walt E. , Gloor Susan , Hastings Gregg , Zuzack John , Winkler James , Koch Kevin 
Published: June 2012

Abstract
Through alterations in the PTEN and PI3K genes, the PI3K / Akt pathway is constitutively activated in human cancers. mTOR kinase plays an unique role in this pathway as the key component of two independent signaling complexes (mTORC1 (raptor - rapamycin sensitive) and mTORC2 (rictor - rapamycin insensitive)) that are involved at multiple branch points in this signaling cascade. As such, inhibition of mTOR kinase inactivates both mTOR complexes and therefore serves as an attractive means to target this integral pathway for the treatment of human malignancy.
We report the biological and pharmaceutical evaluation of our selective mTOR 1/2 kinase inhibitor AR-mTOR-1. AR-mTOR-1 inhibits mTOR kinase with an IC50 of &lt; 10 nM while maintaining selectivity against PI3K as well as a panel of additional lipid kinases, serine/threonine kinases and cytoplasmic and receptor tyrosine kinases. In mechanistic cellular assays, AR-mTOR-1 inhibits pAkt (Ser473), 4E-BP1 (Thr36/46) and pS6 (Ser235/6) with nanomolar potency, thus demonstrating inhibition of signaling from both mTORC1 and mTORC2 complexes. In line with its enzymatic selectivity over PI3K , AR-mTOR-1 does not significantly inhibit pAkt (Thr308) in cells. AR-mTOR-1 is broadly anti-proliferative in both epithelial and hematologic cancer cell lines, irrespective of mutational status, with IC50's ranging from 30 to 550 nM across 20 cell lines, suggesting the potential for broad clinical activity. Once daily dosing of AR-mTOR-1 in several mouse xenograft models, including PC3 prostate, U87 glioblastma, and H460 lung, results in robust anti-tumor activity. Finally, AR-mTOR-1 possesses desired in vitro and in vivo preclinical ADME properties including low clearance, high permeability and good absorption in three preclinical species. In total these data demonstrate that selectively targeting mTORC1 and mTORC2 with AR-mTOR-1 holds promise for broad spectrum clinical utility as a single agent across a wide array of cancer types.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B267.
Abstract B31: Multicellular resistance to bortezomib acquired by mesothelioma spheroids can be reversed by modulation of the Bcl-2 repertoire
Authors: Barbone Dario , Fennell Dean A. , Broaddus V. Courtney 
Published: June 2012

Abstract
Whereas cancer cells may attain a chemoresistant phenotype on a single cell basis (unicellular resistance), they acquire further resistance to apoptosis when they form three-dimensional (3D) structures (multicellular resistance). The multicellular spheroid, a type of in vitro 3D cell culture, has emerged as a valuable platform to study the acquired multicellular resistance of cancer. We have previously shown that mesothelioma, a recalcitrant tumor with significant apoptotic resistance, manifests a high degree of multicellular resistance in vitro when grown as 3D spheroids. One of the treatments considered for mesothelioma is bortezomib, a proteasome inhibitor; bortezomib has been effective as a single agent in multiple myeloma but has been generally ineffective in solid tumors. Bortezomib has been shown to modulate several pro-/anti-apoptotic members of the Bcl-2 family, including upregulation of pro-apoptotic Noxa, thereby shifting the balance towards apoptosis. We asked whether mesothelioma spheroids develop multicellular resistance to bortezomib and whether changes in the Bcl-2 repertoire could account for the acquired resistance. Using monolayers and spheroids grown from two human mesothelioma cell lines, M28 and REN, we found that these cell lines acquired significant multicellular apoptotic resistance to bortezomib when grown as spheroids. Nonetheless, bortezomib inhibited proteasomal activity equally in both monolayers and spheroids and caused the accumulation of a comparable amount of ubiquitinated proteins in both systems. Despite these similarities, we found that the Bcl-2 repertoire was different in spheroids compared to monolayers, both at baseline and after bortezomib. One major difference was that Noxa, although upregulated in monolayers by bortezomib as expected, was not expressed in the spheroids, either at baseline or after bortezomib. The lack of Noxa accounted for some of the resistance because we found that a cell-permeable Noxa-BH3 peptide partially restored the apoptotic response to bortezomib in 3D spheroids. ABT-737, an inhibitor of the anti-apoptotic proteins Bcl-3/xL/w, was even more effective at reversing bortezomib resistance acquired by cells in 3D. In fact, when given alone, ABT-737 was selectively toxic for the spheroids, inducing apoptosis by itself in 3D spheroids but not in the 2D monolayers. In conclusion, we find that Bcl-2 proteins can account for apoptotic resistance in 3D. Manipulation of the Bcl-2 repertoire may be effective alone and may also improve the therapeutic response of mesothelioma to bortezomib therapy.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B31.
Abstract B39: CXCL1 as a putative tumor marker for gastric cancer progression
Authors: Jung Minkyu , Jung Jae-Joon , Noh Se Won , Jeung Hei-Cheul , Kim Tae Soo , Kim Hyo Song , Noh Sung Hoon , Roh Jaekyung , Chung Hyun Cheol , Rha Sung Young 
Published: June 2012

Abstract
Gastric cancer (GC) is a heterogeneous disease and current tumor markers are limited in its application. Therefore finding molecular markers that are able to predict the potential of tumor progression is important for appropriate individualized therapy. With the Cancer Metastasis Research Center (CMRC) microarray database (17K cDNA microarray), we identified differentially expressed genes between 96 cancer and 98 normal gastric tissues using Significant Analysis of Microarray (SAM). Among them, more than 2-fold overexpressed genes in tumor tissues which encode secreted proteins were selected. The selected gene was validated with ELISA assay using sera of 96 GC patients and 48 healthy donors. We first selected 6510 genes which were differentially expressed between 96 cancer and 98 normal gastric tissues with minimal false discovery rate (FDR) of 0.005%. Then, out of 6510 genes, we picked 386 genes which encode secreted proteins based on SOURCE database. Among 386 genes, we focused on the 55 genes overexpressed more that 2-fold in GC compared to normal. With Ingenuity Pathway Analysis, we found 34 genes related to cancer. Especially, CXCL1, chemokine growth-regulated oncogene 1, has been known for its relation with cancer progression in various cancer type, but GC. CXCL1 levels in serum samples of GC patients were significantly elevated compared with healthy donors (p&lt;0.05). Within GC patients, CXCL1 serum levels were increased according to the tumor stage and lymph node metastasis. These findings provide that CXCL1 could be a candidate marker for gastric cancer progression.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B39.
Abstract B50: Leptin and leptin receptor expression in breast cancer
Authors: Yom Cha Kyong , Kim Jun Ho , Kim Hee Sung , Park Yong Lai 
Published: June 2012

Abstract
Background: Leptin is a multifunctional hormone produced by the adipose tissue and involved in the regulation of food intake and energy balance. The aims of this study is to evaluate leptin and leptin receptor (Ob-R) expression in human breast cancer and determine whether it influence the prognosis of the patients with breast cancers.
Methods: We examined the correlation for leptin and Ob-R expression and breast cancer-related pathobiological markers by immunohistochemistry in five hundred and seventeen patients with breast cancer. We analyzed leptin and leptin receptor (Ob-R) expression for overall survival (OS) and relapse-free survival (RFS).
Results: Positive cytoplasmic immunoreactivity was found in 39% for leptin and 79% for Ob-R. The expression of leptin in breast cancer correlated with high Ki-67 labeling index (p=0.019). The leptin expression showed significant correlation with triple negative (TN) type (p=0.022) and epidermal growth factor receptor (EGFR) reactivity (p=0.05). The frequency of Ob-R expression was higher in non-TN breast cancers (p=0.045) and the breast cancers with high Ki-67 labeling index (p=0.06). In univariate survival analysis, clinicopathologic variables with prognostic value included histologic grade, T stage, N stage, HER2 status, Bcl-2, p53, and Ki-67 expression (p&lt;0.05). The patients with leptin-positive breast cancers showed longer OS in negative hormone receptor status. In multivariate survival analysis with Cox proportional hazards model, leptin expression was independent prognostic marker (Hazard ratio=0.22, 95% CI 0.06 and 0.79, p=0.02) in hormone receptor negative breast cancers.
Conclusion: We conclude that leptin leptin expression in breast cancers is significantly associated with Ki-67 labeling index, suggesting association with proliferation activity. In addition, leptin expression is a indicator of favorable tumor features and better survival of hormone receptor negative breast cancer patients.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B50.
Abstract B63: Apaf-1 mislocalization is a strong indicator of drug resistance in B cell lymphomas
Authors: Hirpara Jayshree L. , Loh Thomas , Goh Boon Cher , Pervaiz Shazib 
Published: June 2012

Abstract
Resistance to chemotherapy remains a challenge in the clinical management of diffuse B cell lymphomas despite aggressive chemotherapy such as CHOP and monoclonal CD20. We previously reported that sequestration of Apaf-1 to membrane lipid rafts was responsible for apoptosis resistance in B-cell lymphoma cell lines1. Here, we extended our studies to 60 clinical biopsies from patients with B-cell lymphomas, T-cell lymphomas and reactive lymphadenopathy, to investigate if the resistance to drug-induced apoptosis was, indeed, a function of Apaf-1 mislocalization. Firstly, cells were separated from these biopsies and their sensitivity to a variety of apoptosis inducing agents was assessed. Whereas, most T cell lymphomas as well as reactive lymphadenopathy cells were sensitive to apoptotic stimuli, B cell lymphomas exhibited strong resistance. We then investigated the expression of Apaf-1 and its intracellular localization in these clinical biopsies. To do so, cell fraction was performed to separate cytosol from membrane-enriched fractions. The latter were further subjected to density gradient centrifugation to obtain lipid raft fractions. We show that Apaf-1 was expressed in total cell lysates from B and T cell lymphomas, however upon fractionation the localization was strikingly different. In T cell lymphoma samples as well as in cells derived from reactive lymphadenopathy biopsies, Apaf-1 expression was prominently detected in the cytosol, which correlated with the sensitivity of the cells to apoptotic stimuli. In contrast, whereas cytosolic Apaf-1 expression was significantly lower or absent in almost all B cell lymphomas analyzed, increased localization of the protien was detected in membrane lipid rafts. The latter was confirmed by immunohistochemical analysis of tissues from the same biopsy specimens. Interestingly, the resistance of B cell lymphomas to apoptotic execution (drug-induced or death receptor-mediated) was significantly bypassed upon incubation of cells with pharmacological agents that facilitated the dissociation of Apaf-1 from the lipid rafts to the cytosol. Taken together, our results implicate Apaf-1 mislocalization as a potential diagnostic marker for B-cell lymphomas as well as a predictor of response to therapeutic management.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B63.
Abstract B83: Modulation of the HSP90 cochaperone carboxy-terminus HSC70-interacting protein (CHIP) increases cellular sensitivity to heat shock protein 90 (HSP90) inhibition
Authors: Hughes Edward G. , Sharp Swee Y. , Workman Paul 
Published: June 2012

Abstract
HSP90 operates with cochaperones to enable the correct folding, stabilisation and functioning of multiple oncogenic protein kinases, hormone receptors, and transcription factors, thus making HSP90 an exciting drug target. HSP90 inhibition results in proteasomal degradation of client proteins via ubiquitination by E3 ligases such as CHIP. This cochaperone functions with HSP90 as a molecular switch, sorting misfolded proteins between the degradation and chaperone pathways during a stressed state. We hypothesised that CHIP modulation in human cancer cells may affect their sensitivity to HSP90 inhibition.
A range of levels of constitutive CHIP expression were seen across a panel of human cancer cell lines, as measured by western blotting. Additionally, CHIP levels were unaffected by treatment with HSP90 inhibitors. Interestingly, both overexpression and RNAi knockdown of CHIP caused a significant increase in cellular sensitivity to 17-AAG. Depletion of client proteins were still observed in both overexpression and knockdown cells following treatment with 17-AAG. However, differences in the rate of depletion of some, but not all HSP90 clients, were identified.
The results demonstrate that modulating CHIP levels sensitizes cells to 17- AAG but at the same time that E3-ligase redundancy may exist as a mechanism to ensure client depletion during HSP90 inhibition.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B83.
Abstract B98: Induction of metabolic and oxidative stresses by the novel inhibitor of NAD+ biosynthesis, GMX 1778, for specific killing of human glioblastomas
Authors: Yoo Stephen S. , Cerna David , Carter Donna J. , Flaherty Siobhan M. , Li Hongyun , Takebe Naoko , Watson Mark H. 
Published: June 2012

Abstract
Cancer therapy strategies that selectively target tumors while sparing normal tissues would provide enormous clinical benefit to cancer patients. Central to developing these strategies is identification of tumor specific vulnerabilities and molecular targeted agents targeting these vulnerabilities. GMX1777/1778, a novel inhibitor of NAD+ biosynthesis, is a potent and specific inhibitor of the nicotinamide adnine dinucleotide (NAD+) biosynthesis enzyme, phosphoribosyl transferase (NAMPRT). Since cancer cells have a high rate of NAD+ turnover, modulation of NAD+ biosynthesis would be an attractive target for GMX 1777/1778. In addition to the depletion of NAD+ level, we present evidence of inducing other metabolic and oxidative stresses in a tumor specific manner with minimal damage to normal tissues in vitro and in vivo. Taken together, the cancer therapeutic strategy presented here would provide a novel way of specific killing of tumors.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B98.
Abstract C109: NOV-002 suppresses tumor cell growth by modulating redox-sensitive cell signaling
Authors: Townsend Danyelle M. , Bowers Robert , Pazoles Christopher J. , Tew Kenneth D. 
Published: June 2012

Abstract
Regulation of cell proliferation/survival is complex, impacted by multiple endogenous and exogenous stimuli capable of triggering overlapping and competing signaling pathways whose net effects can be quite cell dependent. Changes in redox status is one regulator of cell life/death decisions under both physiologic and pathologic conditions. Here we report on the anti-proliferative effects of a pharmacologically generated oxidative signal in human tumor cells using NOV-002, a glutathione disulfide-mimetic in advanced clinical trials for oncological indications. NOV-002 has demonstrated efficacy (increased survival and/or decreased tumor growth) in non-small cell lung, breast and ovarian cancers when combined with standard chemotherapeutic agents. In addition, treatment with NOV-002 mitigates chemotherapy-associated hematological toxicity. Pre-clinical data has linked this effect to proliferation of bone marrow progenitor cells subsequent to generation of an oxidative signal, intracellularly and at the cell surface of myeloid lineage cells, leading to activation of multiple kinases known to regulate cell proliferation (e.g. MAP kinases, JAK/STAT kinases). The data presented here extend redox modulation studies with NOV-002 to tumor cells.
SKOV3 cells (a human ovarian tumor cell line) were exposed to NOV-002 (250 uM). Within 5 min after a single treatment, cellular levels of reactive oxygen species (ROS) were significantly elevated indicating the generation of an oxidative signal by NOV-002. This was not, however, sufficient to influence redox-sensitive cell signaling or tumor cell proliferation rate. In contrast, more prolonged exposure to NOV-002 (daily treatment for 5 days) resulted in a sustained elevation in ROS and dose-dependent activation of the proliferation-regulating MAP kinase, JNK, as evidenced by an increase in its active, phosphorylated form. Most importantly, this redox-activated cell signaling effect was associated with a significantly decreased proliferation rate of the SKOV3 cells that persisted even after stopping treatment with NOV-002. Thus, oxidative signal generation and MAP kinase pathway activation by NOV-002 appears to result in cell-type dependent effects on proliferation/survival. In myeloid lineage/bone marrow cells, chronic exposure to NOV-002 leads to increased proliferation while in tumor cells the result is a decrease in proliferation. These dichotomous effects may contribute to the unique clinical profile that NOV-002 has demonstrated to date — increased anti-tumor efficacy and survival combined with enhanced recovery from chemotherapy-induced hematological toxicity.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C109.