bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Mel-18 Acts as a Tumor Suppressor by Repressing Bmi-1 Expression and Down-regulating Akt Activity in Breast Cancer Cells
Authors: Guo Wei-Jian , Zeng Mu-Sheng , Yadav Ajay , Song Li-Bing , Guo Bao-Hong , Band Vimla , Dimri Goberdhan P.
Published: March 2023

Abstract
The Bmi-1 oncogene is overexpressed in a number of malignancies including breast cancer. In addition to Bmi-1, mammalian cells also express four other polycomb group (PcG) proteins that are closely related to Bmi-1. Virtually nothing is known about the role of these PcG proteins in oncogenesis. We have recently reported that Mel-18, a Bmi-1–related PcG protein, negatively regulates Bmi-1 expression, and that its expression negatively correlates with Bmi-1 in proliferating and senescing human fibroblasts. Here, we report that the expression of Bmi-1 and Mel-18 inversely correlates in a number of breast cancer cell lines and in a significant number of breast tumor samples. Overexpression of Mel-18 results in repression of Bmi-1 and reduction of the transformed phenotype in malignant breast cancer cells. Furthermore, the repression of Bmi-1 by Mel-18 is accompanied by the reduction of Akt/protein kinase B (PKB) activity in breast cancer cells. Similarly, Bmi-1 knockdown using RNA interference approach results in down-regulation of Akt/PKB activity and reduction in transformed phenotype of MCF7 cells. Importantly, we show that overexpression of constitutively active Akt overrides tumor-suppressive effect of Mel-18 overexpression and the knockdown of Bmi-1 expression. Thus, our studies suggest that Mel-18 and Bmi-1 may regulate the Akt pathway in breast cancer cells, and that Mel-18 functions as a tumor suppressor by repressing the expression of Bmi-1 and consequently down-regulating Akt activity. [Cancer Res 2007;67(11):5083–9]
Data from Cholesterol Sensitivity of Endogenous and Myristoylated Akt
Authors: Adam Rosalyn M. , Mukhopadhyay Nishit K. , Kim Jayoung , Di Vizio Dolores , Cinar Bekir , Boucher Kelly , Solomon Keith R. , Freeman Michael R.
Published: March 2023

Abstract
The serine-threonine kinase, Akt, has been linked to cholesterol-sensitive signaling mechanisms, suggesting a possible means whereby cholesterol might affect tumor cell growth and survival. However, it has not been shown whether Akt itself, as distinct from upstream components of the pathway (e.g., membrane phosphoinositides), can be directly responsible for cholesterol-mediated effects. Consistent with this possibility, we identified an Akt1 subpopulation in cholesterol-rich lipid raft fractions prepared from LNCaP human prostate cancer cells. Phosphorylation of this Akt subspecies was ablated with methyl-β-cyclodextrin, a cholesterol-binding compound, under conditions where nonlipid raft-resident Akt was unaffected. A myristoylated Akt1 (MyrAkt1) fusion protein expressed in LNCaP cells was found to be highly enriched in lipid rafts, indicating that oncogenic Akt is overrepresented in cholesterol-rich membranes compared with wild-type Akt. Notably, lipid raft-resident MyrAkt1 exhibited a markedly distinct substrate preference compared with MyrAkt1 immunoprecipitated from cytosol and nonraft membrane fractions, suggesting a redirection of signal transduction when the protein is present in cholesterol-rich membranes. Expression of MyrAkt1 in LNCaP cells overcame their characteristic dependence on constitutive signaling through the phosphoinositide 3′-kinase pathway. This protective effect was substantially diminished with cyclodextrin treatment. Phosphorylation of Akt substrates in lipid raft fractions, but not in cytosol/nonraft membrane fractions, was ablated with cyclodextrin. In addition, in control (LacZ transfected) cells, lipid raft fractions were relatively enriched in phosphorylated Akt substrates. Collectively, these data show that a subpopulation of Akt is cholesterol sensitive and that the oncogenic effects conferred by myristoylation arise, in part, from the tendency of the membrane-targeted form of the protein to reside in cholesterol-rich membrane microdomains. [Cancer Res 2007;67(13):6238–46]
Data from Selective Targeting and Potent Control of Tumor Growth Using an EphA2/CD3-Bispecific Single-Chain Antibody Construct
Authors: Hammond Scott A. , Lutterbuese Ralf , Roff Shannon , Lutterbuese Petra , Schlereth Bernd , Bruckheimer Elizabeth , Kinch Michael S. , Coats Steve , Baeuerle Patrick A. , Kufer Peter , Kiener Peter A.
Published: March 2023

Abstract
The EphA2 receptor tyrosine kinase is frequently overexpressed and functionally altered in malignant cells and thus provides opportunities for selective targeting of tumor cells. We describe here the development of a novel, bispecific single-chain antibody (bscAb) referred to as bscEphA2xCD3. This molecule simultaneously targets EphA2 on tumor cells and the T-cell receptor/CD3 complex on T cells and possesses structural and functional characteristics of the recently developed BiTE technology. An EphA2-specific single-chain antibody was selected for recognition of an epitope that is preferentially exposed on malignant cells based on the concept of epitope exclusion; this was fused to a CD3-specific single-chain antibody to generate bscEphA2xCD3. The resultant bscAb redirected unstimulated human T cells to lyse EphA2-expressing tumor cells both in vitro and in vivo. In separate experiments, efficient tumor cell lysis was achieved in vitro at drug concentrations ≤1 μg/mL, at a low T-cell effector-to-tumor target cell ratio (1:1), and with tumor cells that possess few available binding sites (2,400 per cell) for bscEphA2xCD3. Time-lapsed microscopy revealed potent cytotoxic activity of bscEphA2xCD3-activated T cells against monolayers of malignant cells but not against monolayers of nontransformed EphA2-positive cells except at the edges of the monolayer where the target epitope was exposed. BscEphA2xCD3 was also efficacious in human xenograft mouse models modified to show human T-cell killing of tumors. Together, our results reveal opportunities for redirecting the potent activity of cytotoxic T cells towards tumor cells that express selectively accessible epitopes and establish EphA2-specific bscAb molecules as novel and potent therapeutics with selectivity for tumor cells. [Cancer Res 2007;67(8):3927–35]
Data from Estrogen Receptor α Inhibits p53-Mediated Transcriptional Repression: Implications for the Regulation of Apoptosis
Authors: Sayeed Aejaz , Konduri Santhi D. , Liu Wensheng , Bansal Sanjay , Li Fengzhi , Das Gokul M.
Published: March 2023

Abstract
Estrogen receptor α (ERα) and tumor suppressor protein p53 exert opposing effects on cellular proliferation. As a transcriptional regulator, p53 is capable of activating or repressing various target genes. We have previously reported that ERα binds directly to p53, leading to down-regulation of transcriptional activation by p53. In addition to transcriptional activation, transcriptional repression of a subset of target genes by p53 plays important roles in diverse biological processes, such as apoptosis. Here, we report that ERα inhibits p53-mediated transcriptional repression. Chromatin immunoprecipitation assays reveal that ERα interacts in vivo with p53 bound to promoters of Survivin and multidrug resistance gene 1, both targets for transcriptional repression by p53. ERα binding to p53 leads to inhibition of p53-mediated transcriptional regulation of these genes in human cancer cells. Transcriptional derepression of Survivin by ERα is dependent on the p53-binding site on the Survivin promoter, consistent with our observation that p53 is necessary for ERα to access the promoters. Importantly, mutagenic conversion of this site to an activation element enabled ERα to repress p53-mediated transcriptional activation. Further, RNA interference–mediated knockdown of ERα resulted in reduced Survivin expression and enhanced the propensity of MCF-7 cells to undergo apoptosis in response to staurosporine treatment, an effect that was blocked by exogenous expression of Survivin. These results unravel a novel mechanism by which ERα opposes p53-mediated apoptosis in breast cancer cells. The findings could have translational implications in developing new therapeutic and prevention strategies against breast cancer. [Cancer Res 2007;67(16):7746–55]
Data from Proton Pump Inhibitors Induce Apoptosis of Human B-Cell Tumors through a Caspase-Independent Mechanism Involving Reactive Oxygen Species
Authors: De Milito Angelo , Iessi Elisabetta , Logozzi Mariantonia , Lozupone Francesco , Spada Massimo , Marino Maria Lucia , Federici Cristina , Perdicchio Maurizio , Matarrese Paola , Lugini Luana , Nilsson Anna , Fais Stefano
Published: March 2023

Abstract
Proton pumps like the vacuolar-type H+ ATPase (V-ATPase) are involved in the control of cellular pH in normal and tumor cells. Treatment with proton pump inhibitors (PPI) induces sensitization of cancer cells to chemotherapeutics via modifications of cellular pH gradients. It is also known that low pH is the most suitable condition for a full PPI activation. Here, we tested whether PPI treatment in unbuffered culture conditions could affect survival and proliferation of human B-cell tumors. First, we showed that PPI treatment increased the sensitivity to vinblastine of a pre-B acute lymphoblastic leukemia (ALL) cell line. PPI, per se, induced a dose-dependent inhibition of proliferation of tumor B cells, which was associated with a dose- and time-dependent apoptotic-like cytotoxicity in B-cell lines and leukemic cells from patients with pre-B ALL. The effect of PPI was mediated by a very early production of reactive oxygen species (ROS), that preceded alkalinization of lysosomal pH, lysosomal membrane permeabilization, and cytosol acidification, suggesting an early destabilization of the acidic vesicular compartment. Lysosomal alterations were followed by mitochondrial membrane depolarization, release of cytochrome c, chromatin condensation, and caspase activation. However, inhibition of caspase activity did not affect PPI-induced cell death, whereas specific inhibition of ROS by an antioxidant (N-acetylcysteine) significantly delayed cell death and protected both lysosomal and mitochondrial membranes. The proapoptotic activity of PPI was consistent with a clear inhibition of tumor growth following PPI treatment of B-cell lymphoma in severe combined immunodeficient mice. This study further supports the importance of acidity and pH gradients in tumor cell homeostasis and suggests new therapeutic approaches for human B-cell tumors based on PPI. [Cancer Res 2007;67(11):5408–17]
Data from Functional Interplay of p53 and Mus81 in DNA Damage Responses and Cancer
Authors: Pamidi Ashwin , Cardoso Renato , Hakem Anne , Matysiak-Zablocki Elzbieta , Poonepalli Anuradha , Tamblyn Laura , Perez-Ordonez Bayardo , Hande M. Prakash , Sanchez Otto , Hakem Razqallah
Published: March 2023

Abstract
Mus81 plays an integral role in the maintenance of genome stability and DNA repair in mammalian cells. Deficiency of Mus81 in human and mouse cells results in hypersensitivity to interstrand cross-linking (ICL) agents and elevated levels of genomic instability. Furthermore, Mus81-mutant mice are susceptible to spontaneous lymphomas. The role of cellular checkpoints in mediating the phenotypes observed in Mus81-deficient cells and mice is currently unknown. In this study, we have observed increased activation of p53 in Mus81−/− cells in response to ICL-induced DNA damage. In addition, p53 inactivation completely rescued the ICL hypersensitivity of Mus81−/− cells, signifying p53 is essential for the elimination of ICL-damaged cells in the absence of Mus81. Confirming that p53 acts as a critical checkpoint for the Mus81 repair pathway, a synergistic increase of spontaneous and ICL-induced genomic instability was observed in Mus81−/−p53−/− cells. To clarify the genetic interactions of Mus81 and p53 in tumor suppression, we monitored Mus81−/−p53−/− and control mice for the development of spontaneous tumors. Significantly, we show that loss of even a single allele of Mus81 drastically modifies the tumor spectrum of p53-mutant mice and increases their predisposition to developing sarcomas. Our results reveal a key role for p53 in mediating the response to spontaneous and ICL-induced DNA damage that occurs in the absence of Mus81. Furthermore, our data show that loss of Mus81, in addition to p53, is a key step in sarcoma development. [Cancer Res 2007;67(18):8527–35]
Data from Expression of Interleukin-13 Receptor α2 in Glioblastoma Multiforme: Implications for Targeted Therapies
Authors: Jarboe John S. , Johnson Kory R. , Choi Yong , Lonser Russell R. , Park John K.
Published: March 2023

Abstract
Glioblastoma multiforme is the most common primary malignant brain tumor and despite treatment with surgery, radiation, and chemotherapy, the median survival of patients with glioblastoma multiforme is ∼1 year. Glioblastoma multiforme explants and cell lines have been reported to overexpress the interleukin-13 receptor α2 subunit (IL13Rα2) relative to nonneoplastic brain. Based on this finding, a recombinant cytotoxin composed of IL13 ligand and a truncated form of Pseudomonas aeruginosa exotoxin A (IL13-PE38QQR) was developed for the targeted treatment of glioblastoma multiforme tumors. In a recently completed phase III clinical trial, however, IL13-PE38QQR was found to be no more effective than an existing therapy in prolonging survival. To determine possible explanations for this result, we analyzed the relative expression levels of IL13Rα2 in glioblastoma multiforme and nonneoplastic brain specimens using publicly available oligonucleotide microarray databases, quantitative real-time reverse transcription PCR, and immunohistochemical staining. Increased expression of the IL13Rα2 gene relative to nonneoplastic brain was observed in 36 of 81 (44%) and 8 of 17 (47%) tumor specimens by microarray and quantitative real-time reverse transcription PCR analyses, respectively. Immunohistochemical staining of tumor specimens showed highly variable expression of IL13Rα2 protein both within and across specimens. These data indicate that prescreening of subjects may be of benefit in future trials of IL13Rα2 targeting therapies. [Cancer Res 2007;67(17):7983–6]
Data from Complex N-Glycan and Metabolic Control in Tumor Cells
Authors: Mendelsohn Richard , Cheung Pam , Berger Lloyd , Partridge Emily , Lau Ken , Datti Alessandro , Pawling Judy , Dennis James W.
Published: March 2023

Abstract
Golgi β1,6N-acetylglucosaminyltransferase V (Mgat5) produces β1,6GlcNAc-branched complex N-glycans on cell surface glycoproteins that bind to galectins and promote surface residency of glycoproteins, including cytokine receptors. Carcinoma cells from polyomavirus middle T (PyMT) transgenic mice on a Mgat5−/− background have reduced surface levels of epidermal growth factor (EGF) and transforming growth factor-β (TGF-β) receptors and are less sensitive to acute stimulation by cytokines in vitro compared with PyMT Mgat5+/+ tumor cells but are nonetheless tumorigenic when injected into mice. Here, we report that PyMT Mgat5−/− cells are reduced in size, checkpoint impaired, and following serum withdrawal, fail to down-regulate glucose transport, protein synthesis, reactive oxygen species (ROS), and activation of Akt and extracellular signal-regulated kinase. To further characterize Mgat5+/+ and Mgat5−/− tumor cells, a screen of pharmacologically active compounds was done. Mgat5−/− tumor cells were comparatively hypersensitive to the ROS inducer 2,3-dimethoxy-1,4-naphthoquinone, hyposensitive to tyrosine kinase inhibitors, to Golgi disruption by brefeldin A, and to mitotic arrest by colcemid, hydroxyurea, and camptothecin. Finally, regulation of ROS, glucose uptake, and sensitivities to EGF and TGF-β were rescued by Mgat5 expression or by hexosamine supplementation to complex N-glycan biosynthesis in Mgat5−/− cells. Our results suggest that complex N-glycans sensitize tumor cells to growth factors, and Mgat5 is required to balance responsiveness to growth and arrest cues downstream of metabolic flux. [Cancer Res 2007;67(20):9771–80]
Data from Chemosensitization of B-Cell Lymphomas by Methylseleninic Acid Involves Nuclear Factor-κB Inhibition and the Rapid Generation of Other Selenium Species
Authors: Jüliger Simone , Goenaga-Infante Heidi , Lister T. Andrew , Fitzgibbon Jude , Joel Simon P.
Published: March 2023

Abstract
Although recent reports suggest that selenium can modulate the activity of cytotoxic drugs, the mechanism underlying this activity remains unclear. This has been investigated using a panel of human B-cell lymphoma cell lines. The cytotoxic effects of chemotherapeutic agents (e.g., doxorubicin, etoposide, 4-hydroperoxycyclophosphamide, melphalan, and 1-β-d-arabinofuranosylcytosine) were increased by up to 2.5-fold when combined with minimally toxic concentrations (EC5-10) of the organic selenium compound, methylseleninic acid (MSA). DNA strand breaks were identified using comet assays, but the measured genotoxic activity of the combinations did not explain the observed synergistic effects in cell death. However, minimally toxic (EC10) concentrations of MSA induced a 50% decrease in nuclear factor-κB (NF-κB) activity after an exposure of 5 h, similar to that obtained with the specific NF-κB inhibitor, BAY 11-7082. Combinations of BAY 11-7082 with these cytotoxic drugs also resulted in synergism, suggesting that the chemosensitizing activity of MSA is mediated, at least in part, by its effects on NF-κB. Basal intracellular selenium concentration was higher in a MSA-sensitive cell line. After exposure to MSA, methylselenocysteine and selenomethionine were identified as the main intracellular species generated. Volatile selenium species, trapped using solid-phase microextraction fibers, were identified as dimethylselenide and dimethyldiselenide. These volatile species are thought to be the most biologically active forms of selenium. Taken together, these results show that the NF-κB pathway is one target for MSA underlying the interaction between MSA and chemotherapy. These data encourage the further clinical development of selenium as a potential modulator of cytotoxic drug activity in B-cell lymphomas. [Cancer Res 2007;67(22):10984–92]
Data from In vitro Biological Characterization of a Novel, Synthetic Diaryl Pyrazole Resorcinol Class of Heat Shock Protein 90 Inhibitors
Authors: Sharp Swee Y. , Boxall Kathy , Rowlands Martin , Prodromou Chrisostomos , Roe S. Mark , Maloney Alison , Powers Marissa , Clarke Paul A. , Box Gary , Sanderson Sharon , Patterson Lisa , Matthews Thomas P. , Cheung Kwai-Ming J. , Ball Karen , Hayes Angela , Raynaud Florence , Marais Richard , Pearl Laurence , Eccles Sue , Aherne Wynne , McDonald Edward , Workman Paul
Published: March 2023

Abstract
The molecular chaperone heat shock protein 90 (HSP90) has emerged as an exciting molecular target. Derivatives of the natural product geldanamycin, such as 17-allylamino-17-demethoxy-geldanamycin (17-AAG), were the first HSP90 ATPase inhibitors to enter clinical trial. Synthetic small-molecule HSP90 inhibitors have potential advantages. Here, we describe the biological properties of the lead compound of a new class of 3,4-diaryl pyrazole resorcinol HSP90 inhibitor (CCT018159), which we identified by high-throughput screening. CCT018159 inhibited human HSP90β with comparable potency to 17-AAG and with similar ATP-competitive kinetics. X-ray crystallographic structures of the NH2-terminal domain of yeast Hsp90 complexed with CCT018159 or its analogues showed binding properties similar to radicicol. The mean cellular GI50 value of CCT018159 across a panel of human cancer cell lines, including melanoma, was 5.3 μmol/L. Unlike 17-AAG, the in vitro antitumor activity of the pyrazole resorcinol analogues is independent of NQO1/DT-diaphorase and P-glycoprotein expression. The molecular signature of HSP90 inhibition, comprising increased expression of HSP72 protein and depletion of ERBB2, CDK4, C-RAF, and mutant B-RAF, was shown by Western blotting and quantified by time-resolved fluorescent-Cellisa in human cancer cell lines treated with CCT018159. CCT018159 caused cell cytostasis associated with a G1 arrest and induced apoptosis. CCT018159 also inhibited key endothelial and tumor cell functions implicated in invasion and angiogenesis. Overall, we have shown that diaryl pyrazole resorcinols exhibited similar cellular properties to 17-AAG with potential advantages (e.g., aqueous solubility, independence from NQO1 and P-glycoprotein). These compounds form the basis for further structure-based optimization to identify more potent inhibitors suitable for clinical development. [Cancer Res 2007;67(5):2206–16]
Data from Gene and Protein Expression Profiling of Human Ovarian Cancer Cells Treated with the Heat Shock Protein 90 Inhibitor 17-Allylamino-17-Demethoxygeldanamycin
Authors: Maloney Alison , Clarke Paul A. , Naaby-Hansen Soren , Stein Rob , Koopman Jens-Oliver , Akpan Akunna , Yang Alice , Zvelebil Marketa , Cramer Rainer , Stimson Lindsay , Aherne Wynne , Banerji Udai , Judson Ian , Sharp Swee , Powers Marissa , deBilly Emmanuel , Salmons Joanne , Walton Michael , Burlingame Al , Waterfield Michael , Workman Paul
Published: March 2023

Abstract
The promising antitumor activity of 17-allylamino-17-demethoxygeldanamycin (17AAG) results from inhibition of the molecular chaperone heat shock protein 90 (HSP90) and subsequent degradation of multiple oncogenic client proteins. Gene expression microarray and proteomic analysis were used to profile molecular changes in the A2780 human ovarian cancer cell line treated with 17AAG. Comparison of results with an inactive analogue and an alternative HSP90 inhibitor radicicol indicated that increased expression of HSP72, HSC70, HSP27, HSP47, and HSP90β at the mRNA level were on-target effects of 17AAG. HSP27 protein levels were increased in tumor biopsies following treatment of patients with 17AAG. A group of MYC-regulated mRNAs was decreased by 17AAG. Of particular interest and novelty were changes in expression of chromatin-associated proteins. Expression of the heterochromatin protein 1 was increased, and expression of the histone acetyltransferase 1 and the histone arginine methyltransferase PRMT5 was decreased by 17AAG. PRMT5 was shown to be a novel HSP90-binding partner and potential client protein. Cellular protein acetylation was reduced by 17AAG, which was shown to have an antagonistic interaction on cell proliferation with the histone deacetylase inhibitor trichostatin A. This mRNA and protein expression analysis has provided new insights into the complex molecular pharmacology of 17AAG and suggested new genes and proteins that may be involved in response to the drug or be potential biomarkers of drug action. [Cancer Res 2007;67(7):3239–53]
Data from Novel Tryptophan Catabolic Enzyme IDO2 Is the Preferred Biochemical Target of the Antitumor Indoleamine 2,3-Dioxygenase Inhibitory Compound d-1-Methyl-Tryptophan
Authors: Metz Richard , DuHadaway James B. , Kamasani Uma , Laury-Kleintop Lisa , Muller Alexander J. , Prendergast George C.
Published: March 2023

Abstract
Small-molecule inhibitors of indoleamine 2,3-dioxygenase (IDO) are currently being translated to clinic for evaluation as cancer therapeutics. One issue related to trials of the clinical lead inhibitor, d-1-methyl-tryptophan (D-1MT), concerns the extent of its biochemical specificity for IDO. Here, we report the discovery of a novel IDO-related tryptophan catabolic enzyme termed IDO2 that is preferentially inhibited by D-1MT. IDO2 is not as widely expressed as IDO but like its relative is also expressed in antigen-presenting dendritic cells where tryptophan catabolism drives immune tolerance. We identified two common genetic polymorphisms in the human gene encoding IDO2 that ablate its enzymatic activity. Like IDO, IDO2 catabolizes tryptophan, triggers phosphorylation of the translation initiation factor eIF2α, and (reported here for the first time) mobilizes translation of LIP, an inhibitory isoform of the immune regulatory transcription factor NF-IL6. Tryptophan restoration switches off this signaling pathway when activated by IDO, but not IDO2, arguing that IDO2 has a distinct signaling role. Our findings have implications for understanding the evolution of tumoral immune tolerance and for interpreting preclinical and clinical responses to D-1MT or other IDO inhibitors being developed to treat cancer, chronic infection, and other diseases. [Cancer Res 2007;67(15):7082–7]
Data from A Novel Variant of Ileal Bile Acid Binding Protein Is Up-regulated through Nuclear Factor-κB Activation in Colorectal Adenocarcinoma
Authors: Fang Changming , Dean Jarrod , Smith Jeffrey W.
Published: March 2023

Abstract
Ileal bile acid binding protein (IBABP) is the only cytosolic protein known to bind and transport bile acids. Because IBABP is reportedly up-regulated in colorectal cancer, it has been suggested as a link between bile acids and the risk of colorectal cancer. However, in this study, we show that IBABP is not up-regulated. Rather, a novel transcript of the IBABP gene, which encodes an additional 49 NH2-terminal amino acid residues, is up-regulated in colorectal cancer (P < 0.001). The novel transcript, called IBABP-L, is also distinct from IBABP because its transcription is controlled by nuclear factor-κB (NF-κB) rather than by the farnesoid X receptor. Most significantly, IBABP-L is necessary for the survival of HCT116 colon cancer cells in the presence of physiologic levels of the secondary bile acid deoxycholate. Collectively, the studies point toward a unique bile acid response pathway involving NF-κB and IBABP-L that could be useful for diagnosis and could potentially be targeted for therapeutic benefit. [Cancer Res 2007;67(19):9039–46]
Data from Crystal Structure of the T315I Abl Mutant in Complex with the Aurora Kinases Inhibitor PHA-739358
Authors: Modugno Michele , Casale Elena , Soncini Chiara , Rosettani Pamela , Colombo Riccardo , Lupi Rosita , Rusconi Luisa , Fancelli Daniele , Carpinelli Patrizia , Cameron Alexander D. , Isacchi Antonella , Moll Jürgen
Published: March 2023

Abstract
Mutations in the kinase domain of Bcr-Abl are the most common cause of resistance to therapy with imatinib in patients with chronic myelogenous leukemia (CML). Second-generation Bcr-Abl inhibitors are able to overcome most imatinib-resistant mutants, with the exception of the frequent T315I substitution, which is emerging as a major cause of resistance to these drugs in CML patients. Structural studies could be used to support the drug design process for the development of inhibitors able to target the T315I substitution, but until now no crystal structure of the T315I Abl mutant has been solved. We show here the first crystal structure of the kinase domain of Abl T315I in complex with PHA-739358, an Aurora kinase inhibitor currently in clinical development for solid and hematologic malignancies. This compound inhibits in vitro the kinase activity of wild-type Abl and of several mutants, including T315I. The cocrystal structure of T315I Abl kinase domain provides the structural basis for this activity: the inhibitor associates with an active conformation of the kinase domain in the ATP-binding pocket and lacks the steric hindrance imposed by the substitution of threonine by isoleucine. [Cancer Res 2007;67(17):7987–90]
Data from Mechanisms Involved in Synergistic Anticancer Immunity of Anti-4-1BB and Anti-CD4 Therapy
Authors: Choi Beom K. , Kim Young H. , Kang Woo J. , Lee Sun K. , Kim Kwang H. , Shin Su M. , Yokoyama Wayne M. , Kim Tae Y. , Kwon Byoung S.
Published: March 2023

Abstract
Anti-4-1BB–mediated anticancer effects were potentiated by depletion of CD4+ cells in B16F10 melanoma-bearing C57BL/6 mice. Anti-4-1BB induced the expansion and differentiation of polyclonal tumor-specific CD8+ T cells into IFN-γ–producing CD11c+CD8+ T cells. The CD4+ cell depletion was responsible for facilitating immune cell infiltration into tumor tissues and removing some regulatory barriers such as T regulatory and indoleamine-2,3-dioxygenase (IDO)+ dendritic cells. Both monoclonal antibodies (mAb) contributed to the efficient induction of MHC class I molecules on the tumor cells in vivo. The effectors that mediated the anti-4-1BB effect were NKG2D+KLRG1+CD11c+CD8+ T cells that accumulated preferentially in the tumor tissues. Blocking NKG2D reduced the therapeutic effect by 20% to 26%, which may indicate that NKG2D contributes partially to tumor killing by the differentiated CD8+ T cells. Our results indicate that the combination of the two mAbs, agonistic anti-4-1BB and depleting anti-CD4, results in enhanced production of efficient tumor-killing CTLs, facilitation of their infiltration, and production of a susceptible tumor microenvironment. [Cancer Res 2007;67(18):8891–9]
Data from MicroRNA Expression Profiling in Prostate Cancer
Authors: Porkka Kati P. , Pfeiffer Minja J. , Waltering Kati K. , Vessella Robert L. , Tammela Teuvo L.J. , Visakorpi Tapio
Published: March 2023

Abstract
MicroRNAs (miRNA) are small, endogenously expressed noncoding RNAs that negatively regulate expression of protein-coding genes at the translational level. Accumulating evidence, such as aberrant expression of miRNAs, suggests that they are involved in the development of cancer. They have been identified in various tumor types, showing that different sets of miRNAs are usually deregulated in different cancers. To identify the miRNA signature specific for prostate cancer, miRNA expression profiling of 6 prostate cancer cell lines, 9 prostate cancer xenografts samples, 4 benign prostatic hyperplasia (BPH), and 9 prostate carcinoma samples was carried out by using an oligonucleotide array hybridization method. Differential expression of 51 individual miRNAs between benign tumors and carcinoma tumors was detected, 37 of them showing down-regulation and 14 up-regulation in carcinoma samples, thus identifying those miRNAs that could be significant in prostate cancer development and/or growth. There was a significant trend (P = 0.029) between the expression of miRNAs and miRNA locus copy number determined by array comparative genomic hybridization, indicating that genetic aberrations may target miRNAs. Hierarchical clustering of the tumor samples by their miRNA expression accurately separated the carcinomas from the BPH samples and also further classified the carcinoma tumors according to their androgen dependence (hormone naive versus hormone refractory), indicating the potential of miRNAs as a novel diagnostic and prognostic tool for prostate cancer. [Cancer Res 2007;67(13):6130–5]
Data from A Human scFv Antibody against TRAIL Receptor 2 Induces Autophagic Cell Death in Both TRAIL-Sensitive and TRAIL-Resistant Cancer Cells
Authors: Park Kyung-Jin , Lee Seung-Hyun , Kim Tae-In , Lee Hae-Won , Lee Chang-Han , Kim Eun-Hee , Jang Ji-Young , Choi Kyeong Sook , Kwon Myung-Hee , Kim Yong-Sung
Published: March 2023

Abstract
Tumor necrosis factor (TNF)–related apoptosis-inducing ligand (TRAIL) induces apoptotic cell death in a variety of tumor cells without significant cytotoxicity on normal cells. However, many cancer cells with apoptotic defects are resistant to treatment with TRAIL alone, limiting its potential as an anticancer therapeutic. Here, we report on the tumoricidal activity of a human single-chain fragment variable, HW1, which specifically binds to TRAIL receptor 2 (TR2) without competing with TRAIL for the binding. HW1 treatment as a single agent induces autophagic cell death in a variety of both TRAIL-sensitive and TRAIL-resistant cancer cells, but exhibits much less cytotoxicity on normal cells. The HW1-induced autophagic cell death was inhibited by an autophagy inhibitor, 3-methyladenine, or by RNA interference knockdown of Beclin-1 and Atg7. We also show that the HW1-mediated autophagic cell death occurs predominantly via the c-Jun NH2-terminal kinase pathway in a caspase-independent manner. Analysis of the death-inducing signaling complex induced by HW1 binding to TR2 exhibits the recruitment of TNF receptor–associated death domain and TNF receptor–associated factor 2, but not Fas-associated death domain, caspase-8, or receptor-interacting protein, which is distinct from that induced by TRAIL. Our results reveal a novel TR2-mediated signaling pathway triggering autophagic cell death and provides a new strategy for the elimination of cancer cells, including TRAIL-resistant tumors, through nonapoptotic cell death.[Cancer Res 2007;67(15):7327–34]
Data from Inhibition of Prostate Cancer Growth by Muscadine Grape Skin Extract and Resveratrol through Distinct Mechanisms
Authors: Hudson Tamaro S. , Hartle Diane K. , Hursting Stephen D. , Nunez Nomeli P. , Wang Thomas T.Y. , Young Heather A. , Arany Praveen , Green Jeffrey E.
Published: March 2023

Abstract
The phytochemical resveratrol contained in red grapes has been shown to inhibit prostate cancer cell growth, in part, through its antioxidant activity. Muscadine grapes contain unique phytochemical constituents compared with other grapes and are potentially a source for novel compounds with antitumor activities. We compared the antitumor activities of muscadine grape skin extract (MSKE), which we show contains no resveratrol, with that of resveratrol using primary cultures of normal prostate epithelial cells (PrEC) and the prostate cancer cell lines RWPE-1, WPE1-NA22, WPE1-NB14, and WPE1-NB26, representing different stages of prostate cancer progression. MSKE significantly inhibited tumor cell growth in all transformed prostate cancer cell lines but not PrEC cells. Prostate tumor cell lines, but not PrEC cells, exhibited high rates of apoptosis in response to MSKE through targeting of the phosphatidylinositol 3-kinase–Akt and mitogen-activated protein kinase survival pathways. The reduction in Akt activity by MSKE is mediated through a reduction in Akt transcription, enhanced proteosome degradation of Akt, and altered levels of DJ-1, a known regulator of PTEN. In contrast to MSKE, resveratrol did not induce apoptosis in this model but arrested cells at the G1-S phase transition of the cell cycle associated with increased expression of p21 and decreased expression of cyclin D1 and cyclin-dependent kinase 4 proteins. These results show that MSKE and resveratrol target distinct pathways to inhibit prostate cancer cell growth in this system and that the unique properties of MSKE suggest that it may be an important source for further development of chemopreventive or therapeutic agents against prostate cancer. [Cancer Res 2007;67(17):8396–405]
Data from Inactivation of the Candidate Tumor Suppressor Par-4 in Endometrial Cancer
Authors: Moreno-Bueno Gema , Fernandez-Marcos Pablo J. , Collado Manuel , Tendero Mercedes J. , Rodriguez-Pinilla Socorro M. , Garcia-Cao Isabel , Hardisson David , Diaz-Meco Maria T. , Moscat Jorge , Serrano Manuel , Palacios Jose
Published: March 2023

Abstract
Recently, it has been shown that mice deficient in the proapoptotic protein prostate apoptosis response 4 (Par-4) are specifically prone to develop endometrial carcinomas. Based on this, we have examined here the possible role of Par-4 as a tumor suppressor gene in human endometrial cancer. Using cDNA arrays, quantitative reverse transcription-PCR, and immunohistochemistry, we detected Par-4 down-regulation in ∼40% of endometrial carcinomas. This alteration was not associated with phosphatase and tensin homologue (PTEN), K-RAS, or β-catenin mutations, but was more frequent among tumors showing microsatellite instability (MSI) or among tumors that were estrogen receptor positive. Mutational analysis of the complete coding sequence of Par-4 in endometrial cancer cell lines (n = 6) and carcinomas (n = 69) detected a mutation in a single carcinoma, which was localized in exon 3 [Arg (CGA) 189 (TGA) Stop]. Interestingly, Par-4 promoter hypermethylation was detected in 32% of the tumors in association with low levels of Par-4 protein and was more common in MSI-positive carcinomas. Par-4 promoter hypermethylation and silencing was also detected in endometrial cancer cell lines SKUT1B and AN3CA, and reexpression was achieved by treatment with the demethylating agent 5′-aza-2′-deoxycytidine. Together, these data show that Par-4 is a relevant tumor suppressor gene in human endometrial carcinogenesis. [Cancer Res 2007;67(5):1927–34]
Data from Increased Glioma Growth in Mice Depleted of Macrophages
Authors: Galarneau Hugo , Villeneuve Jérôme , Gowing Geneviève , Julien Jean-Pierre , Vallières Luc
Published: March 2023

Abstract
Macrophages can promote the growth of some tumors, such as those of the breast and lung, but it is unknown whether this is true for all tumors, including those of the nervous system. On the contrary, we have previously shown that macrophages can slow the progression of malignant gliomas through a tumor necrosis factor–dependent mechanism. Here, we provide evidence suggesting that this antitumor effect could be mediated by T lymphocytes, as their number was drastically reduced in tumor necrosis factor–deficient mice and inversely correlated with glioma volume. However, this correlation was only observed in allogeneic recipients, prompting a reevaluation of the role of macrophages in a nonimmunogenic context. Using syngeneic mice expressing the herpes simplex virus thymidine kinase under the control of the CD11b promoter, we show that macrophages can exert an antitumor effect without the help of T lymphocytes. Macrophage depletion achieved by ganciclovir treatment resulted in a 33% increase in glioma volume. The antitumor effect of macrophages was not likely due to a tumoricidal activity because phagocytosis or apoptosis of glioma cells, transduced ex vivo with a lentiviral vector expressing green fluorescent protein, was rarely observed. Their antitumor effect was also not due to a destructive action on the tumor vasculature because macrophage depletion resulted in a modest reduction in vascular density. Therefore, this study suggests that macrophages can attenuate glioma growth by an unconventional mechanism. This study also validates a new transgenic model to explore the role of macrophages in cancer. [Cancer Res 2007;67(18):8874–81]
Data from The Soluble α Chain of Interleukin-15 Receptor: A Proinflammatory Molecule Associated with Tumor Progression in Head and Neck Cancer
Authors: Badoual Cécile , Bouchaud Grégory , Agueznay Nour El Houda , Mortier Erwan , Hans Stéphane , Gey Alain , Fernani Fahima , Peyrard Séverine , -Puig Pierre Laurent , Bruneval Patrick , Sastre Xavier , Plet Ariane , Garrigue-Antar Laure , Quintin-Colonna Françoise , Fridman Wolf H. , Brasnu Daniel , Jacques Yannick , Tartour Eric
Published: March 2023

Abstract
Interleukin (IL)-15 is a proinflammatory cytokine, as it induces the production of inflammatory cytokines [IL-6, tumor necrosis factor α (TNFα), IL-17, etc.]. A correlation between high intratumoral IL-15 concentrations and poor clinical outcome in lung and head and neck cancer patients has been recently reported. The purpose of this study was to investigate the role of the soluble α chain of IL-15 receptor (sIL-15Rα), a natural regulator of IL-15, in head and neck cancer. Fifty-three newly diagnosed untreated head and neck cancer patients were included in this study. Quantification of sIL-15Rα was performed with a newly developed RIA. Increased serum sIL-15Rα concentrations were found in head and neck cancer patients and were closely correlated with poor clinical outcome both in terms of locoregional control and survival even on multivariate analysis. sIL-15Rα was mainly produced by tumor cells via proteolytic cleavage of IL-15Rα mediated by ADAM-17. A correlation was observed between ADAM-17 expression in tumor cells and serum sIL-15Rα concentrations. Surprisingly, sIL-15Rα did not act in vitro as an IL-15 antagonist but rather as an enhancer of IL-15–induced proinflammatory cytokines (IL-6, TNFα, and IL-17) that may promote tumor progression. This new tumor evasion mechanism based on amplification of the intratumoral inflammatory reaction is probably not restricted to head and neck cancer, as other tumors have been shown to release sIL-15Rα. Overall, these results support for the first time an original protumor role of sIL-15Rα in cancer. [Cancer Res 2008;68(10):3907–14]
Data from The Cyclin-Dependent Kinase Inhibitor Flavopiridol Potentiates the Effects of Topoisomerase I Poisons by Suppressing Rad51 Expression in a p53-Dependent Manner
Authors: Ambrosini Grazia , Seelman Sharon L. , Qin Li-Xuan , Schwartz Gary K.
Published: March 2023

Abstract
The results of a phase I clinical trial of the topoisomerase I (Topo I) poison CPT-11 followed by the cyclin-dependent kinase inhibitor flavopiridol in patients with advanced solid tumors indicate that patients whose tumors were wild-type, but not mutant, for p53 obtained the most clinical benefit from this combination therapy. We elected to elucidate the mechanistic basis for this effect in isogenic-paired HCT116 colon cancer cells that were either wild-type (+/+) or null (−/−) for p53. With the combination therapy of SN-38 (the active metabolite of CPT-11) followed by flavopiridol, the induction of apoptosis was 5-fold greater in the p53+/+ cells compared with the p53−/− cells. This sequential treatment induced phosphorylation of p53 at Ser15, which interacted with Rad51, a DNA repair protein involved in homologous recombination. Rad51 bound to p53-Ser15 within the first 5 hours of combination therapy, and then was transcriptionally suppressed at 24 hours by flavopiridol only in p53+/+ cells. Microarray analysis also revealed suppression of Rad51 in a p53-dependent manner. Depletion of Rad51 by small interfering RNA (siRNA) sensitized both p53+/+ and p53−/− cells to SN-38–induced apoptosis with increase of γH2AX, a marker of DNA damage. Conversely, overexpression of Rad51 rescued p53+/+ cells from SN→F–induced apoptosis. Because flavopiridol inhibits Cdk9, we found that inhibition of Cdk9 by DRB or by siRNA could recapitulate the flavopiridol effects, with suppression of Rad51 and induction of apoptosis only in p53+/+ cells. In conclusion, after DNA damage by Topo I poisons, flavopiridol targets homologous recombination through a p53-dependent down-regulation of Rad51, resulting in enhancement of apoptosis. [Cancer Res 2008;68(7):2312–20]
Data from High Expression of Lymphocyte-Associated Genes in Node-Negative HER2+ Breast Cancers Correlates with Lower Recurrence Rates
Authors: Alexe Gabriela , Dalgin Gul S. , Scanfeld Daniel , Tamayo Pablo , Mesirov Jill P. , DeLisi Charles , Harris Lyndsay , Barnard Nicola , Martel Maritza , Levine Arnold J. , Ganesan Shridar , Bhanot Gyan
Published: March 2023

Abstract
Gene expression analysis has identified biologically relevant subclasses of breast cancer. However, most classification schemes do not robustly cluster all HER2+ breast cancers, in part due to limitations and bias of clustering techniques used. In this article, we propose an alternative approach that first separates the HER2+ tumors using a gene amplification signal for Her2/neu amplicon genes and then applies consensus ensemble clustering separately to the HER2+ and HER2− clusters to look for further substructure. We applied this procedure to a microarray data set of 286 early-stage breast cancers treated only with surgery and radiation and identified two basal and four luminal subtypes in the HER2− tumors, as well as two novel and robust HER2+ subtypes. HER2+ subtypes had median distant metastasis-free survival of 99 months [95% confidence interval (95% CI), 83–118 months] and 33 months (95% CI, 11–54 months), respectively, and recurrence rates of 11% and 58%, respectively. The low recurrence subtype had a strong relative overexpression of lymphocyte-associated genes and was also associated with a prominent lymphocytic infiltration on histologic analysis. These data suggest that early-stage HER2+ cancers associated with lymphocytic infiltration are a biologically distinct subtype with an improved natural history. [Cancer Res 2007;67(22):10669–76]
Data from Conservation of Genetic Alterations in Recurrent Melanoma Supports the Melanoma Stem Cell Hypothesis
Authors: Sabatino Marianna , Zhao Yingdong , Voiculescu Sonia , Monaco Alessandro , Robbins Paul , Karai Laszlo , Nickoloff Brian J. , Maio Michele , Selleri Silvia , Marincola Francesco M. , Wang Ena
Published: March 2023

Abstract
It is generally accepted that human cancers derive from a mutated single cell. However, the genetic steps characterizing various stages of progression remain unclear. Studying a unique case of metastatic melanoma, we observed that cell lines derived from metachronous metastases arising over a decade retained a central core of genetic stability in spite of divergent phenotypes. In the present study, we expanded our previous observations comparing these autologous cell lines of clonal derivation with allogeneic ones and correlated array comparative genomic hybridization (aCGH) with gene expression profiling to determine their relative contribution to the dynamics of disease progression. aCGH and gene expression profiling were performed on autologous cell lines and allogeneic melanoma cell lines originating from other patients. A striking correlation existed between total extent of genetic imbalances, global transcriptional patterns, and cellular phenotypes. They did not follow a strict temporal progression but stemmed independently at various time points from a central core of genetic stability best explained according to the cancer stem cell hypothesis. Although their contribution was intertwined, genomic imbalances detectable by aCGH contributed only 25% of the transcriptional traits determining autologous tumor distinctiveness. Our study provides important insights about the dynamics of cancer progression and supports the development of targeted anticancer therapies aimed against stable genetic factors that are maintained throughout the end stage of disease. [Cancer Res 2008;68(1):122–31]
Data from Targeting AKT Signaling Sensitizes Cancer to Cellular Immunotherapy
Authors: Hähnel Patricia S. , Thaler Sonja , Antunes Edite , Huber Christoph , Theobald Matthias , Schuler Martin
Published: March 2023

Abstract
The promise of cancer immunotherapy is long-term disease control with high specificity and low toxicity. However, many cancers fail immune interventions, and secretion of immunosuppressive factors, defective antigen presentation, and expression of death ligands or serpins are regarded as main escape mechanisms. Here, we study whether deregulation of growth and survival factor signaling, which is encountered in most human cancers, provides another level of protection against immunologic tumor eradication. We show in two models that activated cell autonomous protein kinase B (PKB)/AKT signaling mediates resistance against tumor suppression by antigen-specific CTLs in vitro and adoptively transferred cellular immune effectors in vivo. PKB/AKT-dependent immunoresistance of established tumors is reversed by genetic suppression of endogenous Mcl-1, an antiapoptotic member of the Bcl-2 family. Mechanistically, deregulated PKB/AKT stabilizes Mcl-1 expression in a mammalian target of rapamycin (mTOR)–dependent pathway. Treatment with the mTOR inhibitor rapamycin effectively sensitizes established cancers to adoptive immunotherapy in vivo. In conclusion, cancer cell–intrinsic PKB/AKT signaling regulates the susceptibility to immune-mediated cytotoxicity. Combined targeting of signal transduction pathways may be critical for improvement of cancer immunotherapies. [Cancer Res 2008;68(10):3899–906]