bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A188: Proapoptotic versus prosurvival function of the MAP kinase p38 induced by HDAC inhibitor in hematological malignant cells
Authors: Dupéré-Richer Daphné , Petruccelli Luca , Retrouvey Hélène , Dobocan Monica , Tomenson Miranda , Pettersson Filippa , Miller Wilson H. 
Published: June 2012

Abstract
Histone deacetylase inhibitors (HDACi) have recently emerged as promising anticancer agents. However, the mechanisms by which HDAC inhibitors arrest proliferation and induce apoptosis in tumor cells is far from clear. Activation of the stress MAP kinases and induction of DNA damage by different HDACi have been reported, however, the potential role of the MAP kinase p38 in the antitumor activity of these drugs has not been described. P38 is known to be activated independently or downstream of DNA damage. The purpose of this study was to elucidate the mechanisms by which the HDACi vorinostat (Zolinza®) triggers apoptosis in haematological malignant cells.
We show that DNA damage as well as activation of p38 occurs relatively early in acute myeloid leukemia (AML) cell lines after treatment with vorinostat. Using comet assays, we detected direct evidence of early DNA damage and western blotting revealed induction of the DNA damage response proteins ATM and Chk2. We performed cell cycle analysis, and observed within the vorinostat-treated AML cell population, cells exiting G1 and accumulating in the G2-M phase of the cell cycle, where they subsequently underwent apoptosis. Notably, downregulation of p38 by shRNA or inhibition of p38 and β activity by the inhibitor SB203580 significantly decreased both G2-M accumulation and apoptosis induced by vorinostat, indicating a pro-apoptotic p38 function.
Interestingly, several other HDACi tested all induced p38 activation but, depending on the HDACi, this activation was found to be either pro or antiapoptotic. The short-chain fatty acid sodium butyrate (NaB) requires p38 for induction of apoptosis, like vorinostat. On the other hand, LBH589, from the structural class encompassing vorinostat, does not depend on p38 for induction of apoptosis. Furthermore, p38 serves as a pro-survival signal when induced by the benzimide MGCD0103.
In conclusion, we have shown that vorinostat-induced apoptosis in AML cells is preceded by generation of DNA damage and accumulation of cells in the G2-M phase of the cell cycle. Further, G2-M arrest and apoptosis induction (but not DNA damage) by vorinostat requires activation of the p38 MAP kinase, which is not the case for all HDACi. Therefore, a better understanding of the role of p38 MAPK in the action of specific HDACi may help in the development of rational combination regimes including these targeted agents.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A188.
Abstract A189: Expression of fusion proteins in acute myeloid leukemia cells increases sensitivity to histone deacetylase inhibitors
Authors: Petruccelli Luca A. , Pettersson Filippa , Dupere-Richer Daphne , Rice Kim L. , Licht Jonathan D. , Miller Wilson H. 
Published: June 2012

Abstract
Acute Myeloid Leukemias (AMLs) are often characterized by chromosomal rearrangements that result in fusion proteins with aberrant transcriptional regulatory activities. These fusion proteins bind to gene promoters and recruit corepressors such as histone deacetylases (HDACs), which remodel chromatin into a closed conformation thereby silencing genes and contributing to a malignant phenotype. Aberrantly silenced genes include tumor suppressor and pro-differentiation genes. In addition, multiple groups have reported a DNA repair deficient phenotype concurrent with the expression of different fusion proteins in leukemia.
Small molecule HDAC inhibitors (HDACi) were devised as a strategy to reverse transcriptional repression. Indeed, many studies have demonstrated the ability of HDACi to re-sensitize leukemic cells to differentiating stimuli. However, other studies have revealed alternate methods by which HDACi exert anti-tumor activity, including induction of apoptosis that may be dependent on induction of ROS, MAPK signaling etc.
We find that low doses of HDACi, including Vorinostat and LBH589, induce cell death in the AML cell line U937 in a dose and time-dependant manner. Further, Vorinostat induced cell death in U937 cells is preceded by DNA damage and a G2/M arrest. This correlates with reports that HDACi repress DNA repair, by down-regulating DNA repair genes and by acetylating repair proteins thereby impairing their repair function.
Due to the inhibitory effect of leukemic fusion proteins on DNA repair, we predicted that DNA damage induced by HDACi, and thus cell death, would be amplified in AML cells expressing PML-RARα and PLZF-RARα fusion proteins. Sensitivity to Vorinostat and LBH589 was tested in three U937 derived cell lines: PR9 (PML-RARα inducible), B412 (PLZF-RARα inducible) and SN4 (mock transfected control). Indeed, induction of PLZF-RARα increased sensitivity of B412 cells to both Vorinostat- and LBH-mediated cell death. Assaying for DNA damage using alkaline comet assay, PR9 and B412 cells displayed an increase in DNA damage when their respective fusion protein is expressed. Nonetheless, the contribution of DNA damage to HDACi-mediated cell death remains unclear and further study is necessary. These findings are significant as they point to fusion protein expressing AMLs as a target group that may respond better to HDACi-based therapies.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A189.
Abstract A216: Distinct peptides derived from the cochaperone Bag1-L inhibit prostate cancer cell growth
Authors: Maddalo Danilo , Neeb Antje , Jehle Katja , Shatkina Liubov , Cato Andrew 
Published: June 2012

Abstract
Introduction and objectives: Bag1 (Bcl-2 associated athanogene-1) is a family of proteins conserved throughout evolution, promoting cell survival and inhibiting apoptosis under stressful conditions. They are found overexpressed in several types of tumors and associated with poor prognosis. Intriguingly, the nuclear isoform of the Bag-1 proteins, Bag-1L, also exhibits pro-apoptotic properties through an unknown mechanism. In extensive deletion mutagenesis studies we identified sequences in the Bag-1L protein that exert pro-apoptotic action. The objective of the study is to characterize the mechanism of action of these sequences and to explore their use as candidate peptides for prostate cancer therapy.
Materials and Methods: In vitro inhibition of tumor cell growth was analyzed in clonogenic assay where prostate cells were transfected with plasmids expressing different Bag-1L peptides. In vivo growth inhibition was analysed by the injection of prostate cells stably expressing the Bag-1L peptides into the flank of athymic nude mice and analyzing their effect on tumor size in vivo. Histological analysis for apoptosis was carried out on the tumor samples. For analyzing the interaction partners of the Bag-1L peptides, the peptides were generated as fusion proteins with glutathione S transferase (GST), immobilized on glutathione agarose beads and allowed to interact with lysates from prostate cells. Specifically bound proteins were then eluted and analysed by mass spectrometry and by Western blotting.
Results: Overexpression of a 68 amino acid sequence of Bag-1L reduced the growth of 22Rv.1 prostate cancer cells but not of benign prostate hyperplasia cells in a clonogenic assay. Stable overexpression of this peptide in the 22Rv.1 prostate cancer cells also reduced cell growth in vivo in athymic nude mice. Histological analysis revealed massive apoptosis in the tumor cells expressing the peptide. Further deletion analysis of the 68 amino acid peptide showed that the N-terminal 40 amino acids but not the C-terminal 29 amino acids are sufficient for the growth inhibitory action. Protein-protein interaction studies using GST-pull down assay demonstrated that the growth inhibitory function of the peptides correlated with their ability to bind glucose regulated proteins 75 and 78 (GRP75 and GRP78). GRP75 and GRP78 have been implicated in tumor formation through their action in the mitochondria and in the endoplasmic reticulum in the regulation of the unfolded protein response.
Conclusions: We have therefore identified Bag1-L peptides which when expressed in prostate tumor cells reduce the growth in vitro as well as in a mouse model of tumor formation. The action of the peptides is to induce apoptosis and it is correlated with their ability to bind the molecular chaperones GRP75 and GRP78.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A216.
Abstract A245: Imidazo[2,1-b]thiazole and imidazo[1,2-a]pyridine amides as novel inhibitors of the insulin-like growth factor (IGF1R) and members of the epidermal growth factor family of tyrosine kinases
Authors: Fidanze Steve D. , Erickson Scott A. , Hubbard Robert D. , Wang Gary T. , Mantei Robert A. , BaMaung Nwe Y. , Clark Richard F. , Sorensen Bryan K. , Kovar Peter , Pappano William , Zhang Qian , Wilsbacher Julie L. , Hu Xiaoming , Tucker Lora A. , Cheng Min , Swinger Kerren K. , Stewart Kent D. , Wang Jieyi , Bell Randy L. , Davidsen Steven K. , Sheppard George S. 
Published: June 2012

Abstract
The insulin-like growth factor 1 receptor (IGF1R) and its ligands, IGF1 and IGF2 are associated with cell growth and resistance to apoptosis. The ErbB axis, consisting of 4 receptor tyrosine kinases (EGFR, ErbB2, ErbB3, and ErbB4) is a longstanding target of cancer chemotherapy. There is a growing body of literature suggesting that targeting a combination of the IGF and ErbB axes would be more effective than targeting either alone. A screen of Abbott's compound collection revealed a scaffold, the imidazothiazoles, which showed activity against EGFR. A similar scaffold from the literature had previously been reported to have IGF1R activity. Optimization of the imidazothiazoles, and a scaffold hop to imidazopyridines, has provided a series of compounds with amide head groups with kinase inhibitory activity against IGF1R, EGFR, and ErbB2. These compounds also demonstrated inhibition of p-IGF1R and p-EGFR in a human epidermoid carcinoma line (A-431), as well as inhibition of p-ErbB2 in a human gastric cancer cell line (N87). This poster will discuss the synthesis and optimization of the imidazothiazoles and imidazopyridines as multitargeted kinase inhibitors.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A245.
Abstract A250: Preclinical combination efficacy and identification of biomarkers of MEK and PI3K inhibitors in phase I
Authors: Hoeflich Klaus , Merchant Mark , Den Otter Doug , Chan Jocelyn , Chan Emily , Orr Christine , Friedman Lori , Chan Iris , Prescott John , Berry Leanne , Koeppen Hartmut , Belvin Marcia 
Published: June 2012

Abstract
Introduction: The Raf/MEK/ERK and PI3K/Akt/mTOR pathways are two major effector pathways downstream of activated Ras and receptor tyrosine kinases. While Ras is an attractive cancer target, direct pharmacological targeting has so far been unsuccessful. We describe preclinical studies combining GDC-0973, an inhibitor of MEK, and GDC-0941, an inhibitor of PI3K, both of which are in Phase I trials.
Summary of Results: GDC-0973 is a selective allosteric orally bioavailable small molecule inhibitor of the MEK1/2 dual specificity kinases. It has nanomolar potency against MEK1/2 in cells, and has potency across a broad range of cancer cell lines, most notably in those that are mutated for B-Raf and K-Ras. GDC-0941 is a selective orally bioavailable small molecule inhibitor of Class I PI3 kinases that has been described previously. Given the widespread and frequently concurrent activation of the Ras/Raf/MEK and Ras/PI3K/Akt pathways in tumors such as melanoma, colorectal, non-small cell lung cancer, and pancreatic cancer, we carried out cellular and in vivo xenograft studies to evaluate the efficacy of GDC-0973 and GDC-0941, both individually and in combination. We demonstrate strong combination efficacy in B-raf or K-ras mutant melanoma, colon and NSCLC models, driven primarily by increased apoptosis. The combination resulted in modulation of markers of both the MEK and PI3K pathways, and we discovered several markers whose modulation correlated with the induction of apoptosis. Continuous suppression of the two pathways is not required for combination efficacy.
Conclusions: The preclinical data indicate that combined use of MEK and PI3K inhibitors can produce greater efficacy than either agent alone at tolerated doses. Additionally, biomarkers have been identified which correlate with induction of apoptosis in the combination regimens.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A250.
Abstract A258: Combined blockade of Src kinase and epidermal growth factor receptor synergistically inhibits growth of pancreas cancer
Authors: Nagaraj Nagathihalli S. , Herndon Jason , Merchant Nipun B. 
Published: June 2012

Abstract
The failure of conventional chemotherapeutic regimes to produce any meaningful impact on survival in patients with pancreatic cancer highlights a desperate need for novel treatment strategies. The purpose of this study was to translate the current understanding of activated tyrosine kinase signaling pathways in pancreas cancer into improved patient therapies by targeting two tyrosine kinases, the epidermal growth factor receptor (EGFR) and the non-receptor Src kinase, which act in complementary pathways. The biochemical effects of individual and combined drug treatment with dasatinib (Sprycel, BMS-354825), a potent Src kinase inhibitor, erlotinib (Tarceva, OSI-774), a tyrosine kinase inhibitor to EGFR and the nucleoside analog gemcitabine were examined in pancreas cancer cell lines in vitro and in vivo. IC50 for dasatinib (DTB), erlotinib and gemcitabine was determined by the MTT proliferation assay against 9 human pancreas cancer cell lines, and sensitive and resistant cell lines were identified. In vitro regulation of cell motility, proliferation, survival, migration, invasion and in vivo tumor growth inhibition was determined. Expression of Ki67, cleaved caspase 3, phosphorylated Src and AKT in tumor xenografts was determined following exposure to combination of drugs.
The combined inhibition of Src with DTB and EGFR with erlotinib results in cooperative attenuation of cell migration, invasion, proliferation and increases in apoptosis of pancreatic cancer cells. Combined inhibition of Src and EGFR also results in cooperative inhibition of multiple signaling pathways including FAK, AKT, Stat3, ERK, JNK, MAPK and decreases cyclin D1 at concentrations that are ineffective as individual agents. The addition of gemcitabine enhances the effects of combined inhibition of Src and EGFR compared to that seen with individual agents alone or in double combination. Mice with tumor xenografts of BxPC3 (sensitive cell line) and Panc1 (resistant cell line) cells treated with DTB, erlotinib or gemcitabine either individually or as two drug or three drug combinations showed that the most effective in vivo anti-tumor effects were seen with the triple combination of DTB, erlotinib and gemcitabine even in xenografts of resistant pancreatic cells.
Pharmacological inhibition of EGFR and Src, in addition to gemcitabine treatment, results in cooperative inhibition of pancreatic tumor cell growth and appears to overcome resistance of single and double agent therapy. These results show that activation of Src and EGFR signaling pathways is evident in pancreas cancer and may be a driver of poor prognosis and chemotherapy resistance and provide a rationale for combination therapy with erlotinib, DTB and gemcitabine in clinical trials of pancreas cancer.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A258.
Abstract A40: MicroRNA expression patterns as potential biomarkers of responsiveness to the MEK1/2 inhibitor, AZD6244, in colorectal cancer cell lines
Authors: Spreafico Anna , Tan Aik Choon , Tentler John J. , Nallapareddy Sujatha , Pitts Todd M. , Eckhardt S. Gail 
Published: June 2012

Abstract
Background: miRNAs are small, ∼22 oligonucleotides which typically act as negative regulators of gene expression. Recent data have demonstrated that aberrant expression of miRNAs may play a key role in the development of certain cancers and may also be involved in resistance to anticancer therapies. In this study, we tested whether miRNA expression patterns in AZD6244-sensitive (S) or -resistant (R) CRC cell lines could be used as potential biomarkers of responsiveness to this agent.
Methods: Responsiveness to AZD6244 (ARRY-142886) was assessed by exposing 24 CRC cell lines to increasing concentrations of the drug and measuring proliferation using the sulforhodamine B method. Sensitivity and resistance to AZD6244 was defined as: S, IC50&lt;0.8 M; and R, IC50 ≥0.8 µM. Baseline total RNA was isolated from 4 S and 3 R cell lines for miRNA and mRNA profiling on Dharmacon miRNA microarray and Affymetrix HG-U133 Plus 2.0 microarray platforms, respectively. For miRNA microarray data pre-processing, 342 miRNA probes with relative intensity of p≤0.01 in at least 2 of the 8 experiments were kept for further data analysis. For mRNA microarray analysis, probe sets representing the same gene were collapsed based on maximum values and the expression levels were converted to a rank-based matrix. Significance Analysis of Microarray (SAM) was used to determine the differentially expressed miRNAs in cell lines S or R to AZD6244.
Results: Out of 24 CRC cell lines analyzed, 7 S and 17 R lines were identified. Six miRNAs were over-expressed in the R cell lines with at least four-fold change vs. S and with a false-discovery rate (FDR)&lt;0.01. TargetScan listed 1181 genes potentially regulated by these six miRNAs. miRNA-target and Affymetrix gene expression profiles were compared and 171 genes that correlated inversely with miRNA expression at FDR&lt;5% were identified. To assess the pathways enriched by these target genes, we queried this gene list against the KEGG database. Interestingly, expression of genes involved in the MAPK signaling pathway were down regulated in the AZD6244 R cell lines, which correlated with overrepresentation of the miRNAs associated with these genes.
Conclusions: In this study, we determined that AZD6244 S and R CRC cell lines exhibit differential expression patterns of miRNAs, which may have potential utility as a predictive biomarker for sensitivity to this drug. Furthermore, we found that overexpression of specific miRNAs in AZD6244 R cell lines correlates with down regulation of genes involved in the MAPK pathway, which may confer resistance to AZD6244. Suppression of these candidate miRNAs may induce sensitivity to AZD6244 in resistant CRC cell lines and therefore may have clinical application in the targeted therapy of patients with advanced CRC.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A40.
Abstract A44: Predictive biomarkers of efficacy to the hedgehog pathway inhibitor, GDC-0449, in advanced basal cell carcinoma and medulloblastoma in phase I studies
Authors: Yauch Robert , Januario Thomas , Fu Ling , Holcomb Thomas , Stinson Jeremy , Pujara Kana , Callahan Christopher , Koeppen Hartmut , Reddy Josina , Von Hoff Daniel , LoRusso Patricia , Rudin Charles , de Sauvage Frederic , Low Jennifer 
Published: June 2012

Abstract
The Hedgehog (Hh) signaling pathway has been directly implicated in the pathogenesis of basal cell carcinoma (BCC) and medulloblastoma (MB). Constitutive Hh signaling, most often due to underlying loss of function mutations in the inhibitory receptor Patched1 (PTCH1), has been demonstrated in a majority of common localized BCCs and approximately 25–30% of sporadic MB cases. In this study, we examined molecular correlatives of clinical efficacy in locally-advanced / metastatic BCC and MB patients treated with GDC-0449, an inhibitor of the Hh pathway that targets the serpentine receptor Smoothened (SMO). An analysis of Hh pathway transcriptional target gene expression in archival tissue biopsies provided evidence for active Hh signaling in patients exhibiting clinical benefit (objective response or disease stabilization) on therapy. This was further supported by the identification of either loss of function or activating mutations in PTCH1 or SMO, respectively. We were unable to provide evidence for active Hh signaling in 2 patients with progressive disease as best response, potentially underlying the reason for lack of efficacy in these patients. In addition to providing molecular support for Hh pathway activity in patients exhibiting treatment benefit, this is the first evidence for Hh pathway dysregulation in the previously uncharacterized, advanced BCC setting. Furthermore, the results begin to support the utility of transcriptional-based tests as a strategy to potentially select the subset of MB patients with Hh-driven disease that would likely benefit on GDC-0449.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A44.
Abstract A49: FDG-PET as an imaging biomarker for the response of xenograft tumors to IGF-1R inhibition
Authors: Wang Yan , Wang Yaolin , Wang Xiaoying , Hailey Judith , Lipari Philip , Seidel-Dugan Cindy , Larsson Steve 
Published: June 2012

Abstract
Insulin-like growth factor 1 receptor (IGF-1R) plays an important role in tumor cell growth and survival. Upon ligand stimulation, IGF-1R, a tyrosine kinase, phosphorylates tyrosine residues on two major substrates, IRS-1 and Shc, which subsequently signal through the Ras/MAPK and PI3 kinase/AKT pathways. Several anti-IGF-1R monoclonal antibodies are in early phase of clinical development for multiple cancer indications. Biomarker strategy is one of the key elements for targeted therapy development. Several avenues of biomarker assessments have been explored in preclinical models. Many of them are not practical in clinical settings due to lack of adequate tumor tissues accessible for biopsy. Positron emission tomography (PET) allows non-invasive and quantitative studies of biological processes in the tumor tissues. [18F]-fluorodeoxy-glucose (FDG) PET, especially, has become a technology that is available in increasing numbers of cancer centers. Here, we describe impact of a fully human anti-IGF-1R monoclonal antibody SCH 717454 on tumor proliferation index and metabolism in xenograft models. SCH 717454 inhibited the Ki67 marker expression and reduced the uptake of 18F-glucose uptake at much earlier time points than changes in tumor volumes. These data provide preclinical support for using FDG-PET as an early non-invasive method in assessing tumor response in clinical development of this agent.
Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A49.