bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Role for Amplification and Expression of Glypican-5 in Rhabdomyosarcoma
Authors: Williamson Daniel , Selfe Joanna , Gordon Tony , Lu Yong-Jie , Pritchard-Jones Kathy , Murai Kasumi , Jones Phil , Workman Paul , Shipley Janet
Published: March 2023

Abstract
Overexpression of genes, through genomic amplification and other mechanisms, can critically affect the behavior of tumor cells. Genomic amplification of the 13q31-32 region is reported in many tumors, including rhabdomyosarcomas that are primarily pediatric sarcomas resembling developing skeletal muscle. The minimum overlapping region of amplification at 13q31-32 in rhabdomyosarcomas was defined as containing two genes: Glypican-5 (GPC5) encoding a cell surface proteoglycan and C13orf25 encompassing the miR-17-92 micro-RNA cluster. Genomic copy number and gene expression analyses of rhabdomyosarcomas indicated that GPC5 was the only gene consistently expressed and up-regulated in all cases with amplification. Constitutive overexpression and knockdown of GPC5 expression in rhabdomyosarcoma cell lines increased and decreased cell proliferation, respectively. A correlation between expression levels of nascent pre-rRNA and GPC5 (P = 0.001), but not a C13orf25 transcript containing miR-17-92, in primary samples supports an association of GPC5 with proliferative capacity in vivo. We show that GPC5 increases proliferation through potentiating the action of the growth factors fibroblast growth factor 2 (FGF2), hepatocyte growth factor (HGF), and Wnt1A. GPC5 enhanced the intracellular signaling of FGF2 and HGF and altered the cellular distribution of FGF2. The mesoderm-inducing effect of FGF2 and FGF4 in Xenopus blastocysts was also enhanced. Our data are consistent with a role of GPC5, in the context of sarcomagenesis, in enhancing FGF signaling that leads to mesodermal cell proliferation without induction of myogenic differentiation. Furthermore, the properties of GPC5 make it an attractive target for therapeutic intervention in rhabdomyosarcomas and other tumors that amplify and/or overexpress the gene. [Cancer Res 2007;67(1):57–65]
Data from A Novel Pathway Involving Melanoma Differentiation Associated Gene-7/Interleukin-24 Mediates Nonsteroidal Anti-inflammatory Drug–Induced Apoptosis and Growth Arrest of Cancer Cells
Authors: Zerbini Luiz F. , Czibere Akos , Wang Yihong , Correa Ricardo G. , Otu Hasan , Joseph Marie , Takayasu Yuko , Silver Moriah , Gu Xuesong , Ruchusatsawat Kriangsak , Li Linglin , Sarkar Devanand , Zhou Jin-Rong , Fisher Paul B. , Libermann Towia A.
Published: March 2023

Abstract
Numerous studies show that nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in chemoprevention or treatment of cancer. Nevertheless, the mechanisms underlying these antineoplastic effects remain poorly understood. Here, we report that induction of the cancer-specific proapoptotic cytokine melanoma differentiation associated gene-7/interleukin-24 (MDA-7/IL-24) by several NSAIDs is an essential step for induction of apoptosis and G2-M growth arrest in cancer cells in vitro and inhibition of tumor growth in vivo. We also show that MDA-7/IL-24–dependent up-regulation of growth arrest and DNA damage inducible 45 α (GADD45α) and GADD45γ gene expression is sufficient for cancer cell apoptosis via c-Jun NH2-terminal kinase (JNK) activation and growth arrest induction through inhibition of Cdc2-cyclin B checkpoint kinase. Knockdown of GADD45α and GADD45γ transcription by small interfering RNA abrogates apoptosis and growth arrest induction by the NSAID treatment, blocks JNK activation, and restores Cdc2-cyclin B kinase activity. Our results establish MDA-7/IL-24 and GADD45α and GADD45γ as critical mediators of apoptosis and growth arrest in response to NSAIDs in cancer cells. (Cancer Res 2006; 66(24): 11922-31)
Data from Oncostatin M (OSM) Cytostasis of Breast Tumor Cells: Characterization of an OSM Receptor β–Specific Kernel
Authors: Underhill-Day Nicholas , Heath John K.
Published: March 2023

Abstract
The interleukin-6 cytokine oncostatin M (OSM) induces potent growth-inhibitory and morphogenic responses in several different tumor cell types, highlighting the importance of OSM signaling mechanisms as targets for therapeutic intervention. The specific molecular pathways involved are not well understood, as OSM can signal through two separate heterodimeric receptor complexes, glycoprotein 130 (gp130)/leukemia inhibitory factor receptor (LIFR) α and gp130/OSM receptor β (OSMRβ). In this investigation, we used a LIFR antagonist to help resolve signaling responses and identify patterns of gene expression elicited by the different receptor complexes. OSM-induced biological effects on breast tumor–derived cell lines were specifically mediated through the gp130/OSMRβ complex. Each cytokine tested exhibited differential signaling capability and manifested both shared and unique patterns of gene activation, emphasizing compositional differences in activator protein-1 transcription factor activity and expression. In particular, OSM strongly activated the c-Jun NH2-terminal kinase (JNK) serine/threonine kinase and downstream components, including activating transcription factor (ATF)/cyclic AMP-responsive element binding protein family member, ATF3. JNK/stress-activated protein kinase kinase inhibition abrogated cell morphogenesis induced by OSM, indicating an important role for this pathway in OSM specificity. These findings identify a core signaling/transcriptional mechanism specific to the OSMRβ in breast tumor cells. (Cancer Res 2006; 66(22): 10891-901)
Data from Chromosomal Breakpoints Affecting Immunoglobulin Loci Are Recurrent in Hodgkin and Reed-Sternberg Cells of Classical Hodgkin Lymphoma
Authors: Martín-Subero José I. , Klapper Wolfram , Sotnikova Anna , Callet-Bauchu Evelyne , Harder Lana , Bastard Christian , Schmitz Roland , Grohmann Susanne , Höppner Jorge , Riemke Jennifer , Barth Thomas F.E. , Berger Françoise , Bernd Heinz-Wolfram , Claviez Alexander , Gesk Stefan , Frank Georgiy A. , Kaplanskaya Irina B. , Möller Peter , Parwaresch Reza M. , Rüdiger Thomas , Stein Harald , Küppers Ralf , Hansmann Martin L. , Siebert Reiner
Published: March 2023

Abstract
Chromosomal breakpoints affecting immunoglobulin (IG) loci are recurrent in many subtypes of B-cell lymphomas. However, despite the predominant B-cell origin of the Hodgkin and Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL), the presence of chromosomal translocations in IG loci has not yet been systematically explored. Therefore, we have investigated a series of cHL for chromosomal breakpoints in the IGH (n = 230), IGL (n = 139), and IGK (n = 138) loci by interphase cytogenetics. Breakpoints in the IGH, IGL, or IGK locus were observed in the HRS cells of 26 of 149 (17%), 2 of 70, and 1 of 77 evaluable cHLs, respectively. The IG partners could be identified in eight cHLs and involved chromosomal bands 2p16 (REL), 3q27 (BCL6, two cases), 8q24.1 (MYC), 14q24.3, 16p13.1, 17q12, and 19q13.2 (BCL3/RELB). In 65 of 85 (76%) cHLs evaluable for an IGH triple-color probe, the HRS cells showed evidence for a (partial) deletion of the IGH constant region, suggesting the presence of class switch recombination (CSR). Furthermore, analyses with this probe in cases with IGH breakpoints indicated that at least part of them seem to be derived from CSR defects. Our results show that chromosomal breakpoints affecting the IG loci are recurrent in cHL. (Cancer Res 2006; 66(21): 10332-8)
Data from A Single Nucleotide Polymorphism Chip-Based Method for Combined Genetic and Epigenetic Profiling: Validation in Decitabine Therapy and Tumor/Normal Comparisons
Authors: Yuan Eric , Haghighi Fatemeh , White Susan , Costa Ramiro , McMinn Julie , Chun Kathy , Minden Mark , Tycko Benjamin
Published: March 2023

Abstract
Progress on several unresolved issues in cancer epigenetics will benefit from rapid and standardized methods for profiling DNA methylation genome-wide. In the area of epigenetic therapy, the demethylating drug decitabine (5-aza-2′-deoxycytidine) is increasingly used to treat acute myelogenous leukemia and myelodysplastic syndrome, but the mechanisms of its anticancer activity have remained unclear. Given the clinical efficacy of decitabine and the uncertainties about its mode of action, it will be useful to optimize methods for following DNA methylation as a biochemical response in individual patients. Here, we describe a single nucleotide polymorphism (SNP) chip-based method (MSNP) for profiling DNA methylation. Using this procedure, the extent of demethylation in bone marrow aspirates from patients with leukemia receiving decitabine can be assessed genome-wide using commercially available (Affymetrix) SNP chips. We validated the accuracy of MSNP by comparing the results with combined bisulfite restriction analysis and by sequencing cloned PCR products from bisulfite-converted DNA. We further validated MSNP in a Wilms' tumor/normal kidney comparison, comparing the results with methylation-sensitive Southern blotting. MSNP simultaneously detects aberrations in DNA copy number and loss of heterozygosity, making it a generally useful approach for combined genetic and epigenetic profiling in tissue samples from cancer patients. (Cancer Res 2006; 66(7): 3443-51)
Data from Bone Marrow–Derived Stromal Cells Express Lineage-Related Messenger RNA Species
Authors: Direkze Natalie C. , Jeffery Rosemary , Hodivala-Dilke Kairbaan , Hunt Toby , Playford Raymond J. , Elia George , Poulsom Richard , Wright Nicholas A. , Alison Malcolm R.
Published: March 2023

Abstract
Evidence has emerged that bone marrow cells have a greater degree of plasticity than previously thought. However, there has been a call to establish proof that these bone marrow–derived cells function appropriately in their new environment. We have already shown that the bone marrow contributes to myofibroblasts in multiple organs and that this is exacerbated by injury and occurs in a mouse tumor model. Here, we provide evidence that these cells are functioning appropriately by showing that bone marrow–derived myofibroblasts are expressing mRNA for the α1 chain of type I (pro)collagen using a new customized technique. This provides evidence that the bone marrow-tumor stroma axis is functionally relevant and may therefore subsequently be exploited to develop new strategies for anticancer therapy. (Cancer Res 2006; 66(3): 1265-9)
Data from A Specific Role for AKT3 in the Genesis of Ovarian Cancer through Modulation of G2-M Phase Transition
Authors: Cristiano Briony E. , Chan Joanna C. , Hannan Katherine M. , Lundie Nicole A. , Marmy-Conus Nelly J. , Campbell Ian G. , Phillips Wayne A. , Robbie Melissa , Hannan Ross D. , Pearson Richard B.
Published: March 2023

Abstract
Ovarian cancer is the major cause of death from gynecological malignancy, and there is an urgent need for new therapeutic targets. The phosphatidylinositol 3-kinase (PI3K)/AKT pathway has been strongly implicated in the genesis of ovarian cancer. However, to identify and evaluate potential targets for therapeutic intervention, it is critical to understand the mechanism by which the PI3K/AKT pathway facilitates ovarian carcinogenesis. Here, we show that AKT3 is highly expressed in 19 of 92 primary ovarian tumors. Strikingly, purified AKT3 exhibited up to 10-fold higher specific activity than AKT1, potentially amplifying the effects of AKT3 overexpression. Consistent with this finding, AKT3 levels in a range of ovarian cancer cell lines correlated with total AKT activity and proliferation rates, implicating AKT3 as a key mediator of ovarian oncogenesis. Specific silencing of AKT3 using short hairpin RNA markedly inhibited proliferation of the two cell lines with highest AKT3 expression and total AKT activity, OVCA429 and DOV13, by slowing G2-M phase transition. These findings are consistent with AKT3 playing a key role in the genesis of at least one subset of ovarian cancers. (Cancer Res 2006; 66(24): 11718-25)
Data from Determination of Cancer Risk Associated with Germ Line BRCA1 Missense Variants by Functional Analysis
Authors: Carvalho Marcelo A. , Marsillac Sylvia M. , Karchin Rachel , Manoukian Siranoush , Grist Scott , Swaby Ramona F. , Urmenyi Turan P. , Rondinelli Edson , Silva Rosane , Gayol Luis , Baumbach Lisa , Sutphen Rebecca , Pickard-Brzosowicz Jennifer L. , Nathanson Katherine L. , Sali Andrej , Goldgar David , Couch Fergus J. , Radice Paolo , Monteiro Alvaro N.A.
Published: March 2023

Abstract
Germ line inactivating mutations in BRCA1 confer susceptibility for breast and ovarian cancer. However, the relevance of the many missense changes in the gene for which the effect on protein function is unknown remains unclear. Determination of which variants are causally associated with cancer is important for assessment of individual risk. We used a functional assay that measures the transactivation activity of BRCA1 in combination with analysis of protein modeling based on the structure of BRCA1 BRCT domains. In addition, the information generated was interpreted in light of genetic data. We determined the predicted cancer association of 22 BRCA1 variants and verified that the common polymorphism S1613G has no effect on BRCA1 function, even when combined with other rare variants. We estimated the specificity and sensitivity of the assay, and by meta-analysis of 47 variants, we show that variants with <45% of wild-type activity can be classified as deleterious whereas variants with >50% can be classified as neutral. In conclusion, we did functional and structure-based analyses on a large series of BRCA1 missense variants and defined a tentative threshold activity for the classification missense variants. By interpreting the validated functional data in light of additional clinical and structural evidence, we conclude that it is possible to classify all missense variants in the BRCA1 COOH-terminal region. These results bring functional assays for BRCA1 closer to clinical applicability. [Cancer Res 2007;67(4):1494–501]
Data from Membrane Ganglioside Enrichment Lowers the Threshold for Vascular Endothelial Cell Angiogenic Signaling
Authors: Liu Yihui , McCarthy James , Ladisch Stephan
Published: March 2023

Abstract
Malignant tumor progression depends on angiogenesis, requiring vascular endothelial cell migration, and proliferation, triggered by tumor-derived vascular endothelial cell growth factor (VEGF). We show that gangliosides, which are actively shed by tumor cells and bind to normal cells in the tumor microenvironment, have the potential to sensitize vascular endothelial cells to respond to subthreshold levels of VEGF: Ganglioside enrichment of human umbilical vein vascular endothelial cells (HUVEC) caused very low, normally barely stimulatory, VEGF concentrations to trigger robust VEGF receptor dimerization and autophosphorylation, as well as activation of downstream signaling pathways, and cell proliferation and migration. Thus, by dramatically lowering the threshold for growth factor activation of contiguous normal stromal cells, shed tumor gangliosides may promote tumor progression by causing these normal cells to become increasingly autonomous from growth factor requirements by a process that we term tumor-induced progression of the microenvironment. (Cancer Res 2006; 66(21): 10408-14)
Data from Ataxia Telangiectasia Mutated Down-regulates Phospho-Extracellular Signal-Regulated Kinase 1/2 via Activation of MKP-1 in Response to Radiation
Authors: Nyati Mukesh K. , Feng Felix Y. , Maheshwari Divya , Varambally Sooryanarayana , Zielske Steven P. , Ahsan Aarif , Chun Patrick Y. , Arora Vinay A. , Davis Mary A. , Jung Mira , Ljungman Mats , Canman Christine E. , Chinnaiyan Arul M. , Lawrence Theodore S.
Published: March 2023

Abstract
Ataxia telangiectasia mutated (ATM) kinase plays a crucial role in the cellular response to DNA damage and in radiation resistance. Although much effort has focused on the relationship between ATM and other nuclear signal transducers, little is known about interactions between ATM and mitogenic signaling pathways. In this study, we show a novel relationship between ATM kinase and extracellular signal-regulated kinase 1/2 (ERK1/2), a key mitogenic stimulator. Activation of ATM by radiation down-regulates phospho-ERK1/2 and its downstream signaling via increased expression of mitogen-activated protein kinase phosphatase MKP-1 in both cell culture and tumor models. This dephosphorylation of ERK1/2 is independent of epidermal growth factor receptor (EGFR) activity and is associated with radioresistance. These findings show a new function for ATM in the control of mitogenic pathways affecting cell signaling and emphasize the key role of ATM in coordinating the cellular response to DNA damage. (Cancer Res 2006; 66(24): 11554-9)
Data from Cyclooxygenase-2 Inhibition Suppresses αvβ6 Integrin–Dependent Oral Squamous Carcinoma Invasion
Authors: Nystrom Maria L. , McCulloch Diana , Weinreb Paul H. , Violette Shelia M. , Speight Paul M. , Marshall John F. , Hart Ian R. , Thomas Gareth J.
Published: March 2023

Abstract
Worldwide oral squamous cell carcinoma (OSCC) represents about 5.5% of all malignancies, with ∼30,000 new cases each year in the United States. The integrin αvβ6 and the enzyme cyclooxygenase-2 (COX-2) are implicated in OSCC progression and have been suggested as possible therapeutic targets. Each protein also is reported to identify dysplasias at high risk of malignant transformation, and current clinical trials are testing the efficacy of nonsteroidal anti-inflammatory drugs (NSAID) at preventing OSCC development. Given the probable increased expression of αvβ6 and COX-2 in OSCC and the inhibition of several integrins by NSAIDs, we investigated whether NSAIDs affected αvβ6-dependent cell functions. We found that expression of both αvβ6 and COX-2 was significantly higher in OSCC compared with oral epithelial dysplasias. Neither protein preferentially identified those dysplastic lesions that became malignant. Using OSCC cell lines, modified to express varying levels of αvβ6, we assessed the effect of COX-2 inhibition on cell invasion. We found that the COX-2 inhibitor NS398 inhibited specifically αvβ6-dependent, but not αvβ6-independent, OSCC invasion in vitro and in vivo, and this effect was modulated through prostaglandin E2 (PGE2)–dependent activation of Rac-1. Transient expression of constitutively active Rac-1, or addition of the COX-2 metabolite PGE2, prevented the anti-invasive effect of NS398. Conversely, RNA interference down-regulation of Rac-1 inhibited αvβ6-dependent invasion. These findings suggest that COX-2 and αvβ6 interact in promoting OSCC invasion. This is a novel mechanism that, given the ubiquity of αvβ6 expression by head and neck cancers, raises the possibility that NSAIDs could protect against OSCC invasion. (Cancer Res 2006; 66(22): 10833-42)
Data from Extracellular Signal-Related Kinase Positively Regulates Ataxia Telangiectasia Mutated, Homologous Recombination Repair, and the DNA Damage Response
Authors: Golding Sarah E. , Rosenberg Elizabeth , Neill Steven , Dent Paul , Povirk Lawrence F. , Valerie Kristoffer
Published: March 2023

Abstract
The accurate joining of DNA double-strand breaks by homologous recombination repair (HRR) is critical to the long-term survival of the cell. The three major mitogen-activated protein (MAP) kinase (MAPK) signaling pathways, extracellular signal-regulated kinase (ERK), p38, and c-Jun-NH2-kinase (JNK), regulate cell growth, survival, and apoptosis. To determine the role of MAPK signaling in HRR, we used a human in vivo I-SceI–based repair system. First, we verified that this repair platform is amenable to pharmacologic manipulation and show that the ataxia telangiectasia mutated (ATM) kinase is critical for HRR. The ATM-specific inhibitor KU-55933 compromised HRR up to 90% in growth-arrested cells, whereas this effect was less pronounced in cycling cells. Then, using well-characterized MAPK small-molecule inhibitors, we show that ERK1/2 and JNK signaling are important positive regulators of HRR in growth-arrested cells. On the other hand, inhibition of the p38 MAPK pathway generated an almost 2-fold stimulation of HRR. When ERK1/2 signaling was stimulated by oncogenic RAF-1, an ∼2-fold increase in HRR was observed. KU-55933 partly blocked radiation-induced ERK1/2 phosphorylation, suggesting that ATM regulates ERK1/2 signaling. Furthermore, inhibition of MAP/ERK kinase (MEK)/ERK signaling resulted in severely reduced levels of phosphorylated (S1981) ATM foci but not γ-H2AX foci, and suppressed ATM phosphorylation levels >85% throughout the cell cycle. Collectively, these results show that MAPK signaling positively and negatively regulates HRR in human cells. More specifically, ATM-dependent signaling through the RAF/MEK/ERK pathway is critical for efficient HRR and for radiation-induced ATM activation, suggestive of a regulatory feedback loop between ERK and ATM. [Cancer Res 2007;67(3):1046–53]
Data from Interaction of MLL Amino Terminal Sequences with Menin Is Required for Transformation
Authors: Caslini Corrado , Yang Zhaohai , El-Osta Mohamad , Milne Thomas A. , Slany Robert K. , Hess Jay L.
Published: March 2023

Abstract
Rearrangements of the mixed lineage leukemia gene MLL are associated with aggressive lymphoid and myeloid leukemias. The resulting MLL fusion proteins enforce high-level expression of HOX genes and the HOX cofactor MEIS1, which is pivotal for leukemogenesis. Both wild-type MLL and MLL fusion proteins interact with the tumor suppressor menin and with the Hoxa9 locus in vivo. Here, we show that MLL sequences between amino acids 5 and 44 are required for interaction with menin and for the transformation of hematopoietic progenitors. Blocking the MLL-menin interaction by the expression of a dominant negative inhibitor composed of amino terminal MLL sequences down-regulates Meis1 expression and inhibits cell proliferation, suggesting that targeting this interaction may be an effective therapeutic strategy for leukemias with MLL rearrangements. [Cancer Res 2007;67(15):7275–83]
Data from Genome-Wide Allelic Imbalance Analysis of Pediatric Gliomas by Single Nucleotide Polymorphic Allele Array
Authors: Wong Kwong-Kwok , Tsang Yvonne T.M. , Chang Yi-Mieng , Su Jack , Di Francesco Angela M. , Meco Daniela , Riccardi Riccardo , Perlaky Laszlo , Dauser Robert C. , Adesina Adekunle , Bhattacharjee Meenakshi , Chintagumpala Murali , Lau Ching C.
Published: March 2023

Abstract
Using single nucleotide polymorphic (SNP) allele arrays, we analyzed 28 pediatric gliomas consisting of 14 high-grade gliomas and 14 low-grade gliomas. Most of the low-grade gliomas had no detectable loss of heterozygosity (LOH) in any of the 11,562 SNP loci; exceptions were two gangliogliomas (3q and 9p), one astrocytoma (6q), and two subependymal giant cell astrocytomas (16p and 21q). On the other hand, all high-grade gliomas had various degrees of LOH affecting 52 to 2,168 SNP loci on various chromosomes. LOH occurred most frequently in regions located at 4q (54%), 6q (46%), 9p (38%), 10q (38%), 11p (38%), 12 (38%), 13q (69%), 14q (54%), 17 (38%), 18p (46%), and 19q (38%). We also detected amplifications of epidermal growth factor receptor (EGFR) or platelet-derived growth factor receptor α (PDGFRα) in a few of the 13 cases of glioblastoma multiforme analyzed. Interestingly, the amplified EGFR and PDGFRα were located within regions of LOH. SNP loci with LOH and copy number changes were validated by sequencing and quantitative PCR, respectively. Our results indicate that, in some pediatric glioblastoma multiforme, one allele each of EGFR and PDGFRα was lost but the remaining allele was amplified. This may represent a new molecular mechanism underlying tumor progression. (Cancer Res 2006; 66(23): 11172-8)
Data from Antibody-Maytansinoid Conjugates Are Activated in Targeted Cancer Cells by Lysosomal Degradation and Linker-Dependent Intracellular Processing
Authors: Erickson Hans K. , Park Peter U. , Widdison Wayne C. , Kovtun Yelena V. , Garrett Lisa M. , Hoffman Karen , Lutz Robert J. , Goldmacher Victor S. , Blättler Walter A.
Published: March 2023

Abstract
Antibody-drug conjugates are targeted anticancer agents consisting of a cytotoxic drug covalently linked to a monoclonal antibody for tumor antigen–specific activity. Once bound to the target cell-surface antigen, the conjugate must be processed to release an active form of the drug, which can reach its intracellular target. Here, we used both biological and biochemical methods to better define this process for antibody-maytansinoid conjugates. In particular, we examined the metabolic fate in cells of huC242-maytansinoid conjugates containing either a disulfide linker (huC242-SPDB-DM4) or a thioether linker (huC242-SMCC-DM1). Using cell cycle analysis combined with lysosomal inhibitors, we showed that lysosomal processing is required for the activity of antibody-maytansinoid conjugates, irrespective of the linker. We also identified and characterized the released maytansinoid molecules from these conjugates, and measured their rate of release compared with the kinetics of cell cycle arrest. Both conjugates are efficiently degraded in lysosomes to yield metabolites consisting of the intact maytansinoid drug and linker attached to lysine. The lysine adduct is the sole metabolite from the thioether-linked conjugate. However, the lysine metabolite generated from the disulfide-linked conjugate is reduced and S-methylated to yield the lipophilic and potently cytotoxic metabolite, S-methyl-DM4. These findings provide insight into the mechanism of action of antibody-maytansinoid conjugates in general, and more specifically, identify a biochemical mechanism that may account for the significantly enhanced antitumor efficacy observed with disulfide-linked conjugates. (Cancer Res 2006; 66(8): 4426-33)
Data from Pharmacogenomic Identification of Novel Determinants of Response to Chemotherapy in Colon Cancer
Authors: Boyer John , Allen Wendy L. , McLean Estelle G. , Wilson Peter M. , McCulla Andrea , Moore Stephen , Longley Daniel B. , Caldas Carlos , Johnston Patrick G.
Published: March 2023

Abstract
DNA microarray analysis was used to analyze the transcriptional profile of HCT116 colorectal cancer cells that were treated with 5-fluorouracil (5-FU) or oxaliplatin and selected for resistance to these agents. Bioinformatic analyses identified sets of genes that were constitutively dysregulated in drug-resistant cells and transiently altered following acute exposure of parental cells to drug. We propose that these genes may represent molecular signatures of sensitivity to 5-FU and oxaliplatin. Using real-time reverse transcription-PCR (RT-PCR), the robustness of our microarray data was shown with a strong overall concordance of expression trends for ≥82% (oxaliplatin) and ≥85% (5-FU) of a representative subset of genes. Furthermore, strong correlations between the microarray and real-time RT-PCR measurements of average fold changes in gene expression were observed for both the 5-FU (R2 ≥ 0.73) and oxaliplatin gene sets (R2 ≥ 0.63). Functional analysis of three genes identified in the microarray study [prostate-derived factor (PDF), calretinin, and spermidine/spermine N1-acetyl transferase (SSAT)] revealed their importance as novel regulators of cytotoxic drug response. These data show the power of this novel microarray-based approach to identify genes which may be important markers of response to treatment and/or targets for therapeutic intervention. (Cancer Res 2006; 66(5): 2765-77)
Data from p53 Activation in Response to Mitotic Spindle Damage Requires Signaling via BubR1-Mediated Phosphorylation
Authors: Ha Geun-Hyoung , Baek Kwan-Hyuck , Kim Hyun-Soo , Jeong Sook-Jung , Kim Chang-Min , McKeon Frank , Lee Chang-Woo
Published: March 2023

Abstract
The mitotic spindle checkpoint plays a crucial role in regulating accurate chromosome segregation and preventing the adaptation of multiploid progeny cells. Recent reports have indicated that the induction of p53 by mitotic checkpoint activation is essential for protecting cells from abnormal chromosome ploidization caused by mitotic failure. However, although studies have shown that p53 deficiencies arrest mitosis, compromise apoptosis, and may cause profound aneuploidy, the molecular mechanisms leading to p53 induction following mitotic checkpoint activation remain unknown. Here, we show that the BubR1 mitotic checkpoint kinase interacts with p53 both in vitro and in vivo, with higher levels of interaction in mitotic cells. This interaction contributes to p53 phosphorylation. Silencing of BubR1 expression reduces the phosphorylation and stability of p53, whereas exogenous introduction of BubR1 proteins into BubR1-depleted cells recovers p53 stability. In addition, inhibition of BubR1 expression in the presence of a microtubule inhibitor accelerates chromosomal instability and polyploidy in p53-null cells. These results collectively suggest that p53 activation in response to mitotic spindle damage requires signaling via BubR1-mediated phosphorylation. [Cancer Res 2007;67(15):7155–64]
Data from Lithium Treatment Prevents Neurocognitive Deficit Resulting from Cranial Irradiation
Authors: Yazlovitskaya Eugenia M. , Edwards Eric , Thotala Dinesh , Fu Allie , Osusky Kate L. , Whetsell William O. , Boone Braden , Shinohara Eric T. , Hallahan Dennis E.
Published: March 2023

Abstract
Curative cancer treatment regimens often require cranial irradiation, resulting in lifelong neurocognitive deficiency in cancer survivors. This deficiency is in part related to radiation-induced apoptosis and decreased neurogenesis in the subgranular zone of the hippocampus. We show that lithium treatment protects irradiated hippocampal neurons from apoptosis and improves cognitive performance of irradiated mice. The molecular mechanism of this effect is mediated through multiple pathways, including Akt/glycogen synthase kinase-3β (GSK-3β) and Bcl-2/Bax. Lithium treatment of the cultured mouse hippocampal neurons HT-22 induced activation of Akt (1.5-fold), inhibition of GSK-3β (2.2-fold), and an increase in Bcl-2 protein expression (2-fold). These effects were sustained when cells were treated with lithium in combination with ionizing radiation. In addition, this combined treatment led to decreased expression (40%) of the apoptotic protein Bax. The additional genes regulated by lithium were identified by microarray, such as decorin and Birc1f. In summary, we propose lithium treatment as a novel therapy for prevention of deleterious neurocognitive consequences of cranial irradiation. (Cancer Res 2006; 66(23): 11179-86)
Data from Stalled Replication Induces p53 Accumulation through Distinct Mechanisms from DNA Damage Checkpoint Pathways
Authors: Ho Chui Chui , Siu Wai Yi , Lau Anita , Chan Wan Mui , Arooz Talha , Poon Randy Y.C.
Published: March 2023

Abstract
Stalled replication forks induce p53, which is required to maintain the replication checkpoint. In contrast to the well-established mechanisms of DNA damage-activated p53, the downstream effectors and upstream regulators of p53 during replication blockade remain to be deciphered. Hydroxyurea triggered accumulation of p53 through an increase in protein stability. The requirement of p53 accumulation for the replication checkpoint was not due to p21CIP1/WAF1 as its down-regulation with short-hairpin RNA did not affect the checkpoint. Similar to DNA damage, stalled replication triggered the activation of the MRN–ataxia telangiectasia mutated (ATM)/ATM and Rad3-related–CHK1/CHK2 axis. Down-regulation of CHK1 or CHK2, however, reduced p53 basal expression but not the hydroxyurea-dependent induction. Moreover, p53 was still stabilized in ataxia telangiectasia cells or in cells treated with caffeine, suggesting that ATM was not a critical determinant. These data also suggest that the functions of ATM, CHK1, and CHK2 in the replication checkpoint were not through the p53-p21CIP1/WAF1 pathway. In contrast, induction of p53 by hydroxyurea was defective in cells lacking NBS1 and BLM. In this connection, the impaired replication checkpoint in several other genetic disorders has little correlation with the ability to stabilize p53. These data highlighted the different mechanisms involved in the stabilization of p53 after DNA damage and stalled replication forks. (Cancer Res 2006; 66(4): 2233-41)
Data from Copper-Transporting P-Type ATPase, ATP7A, Confers Multidrug Resistance and Its Expression Is Related to Resistance to SN-38 in Clinical Colon Cancer
Authors: Owatari Satsuki , Akune Satoshi , Komatsu Masaharu , Ikeda Ryuji , Firth Stephen D. , Che Xiao-Fang , Yamamoto Masatatsu , Tsujikawa Kazutake , Kitazono Masaki , Ishizawa Takashi , Takeuchi Toru , Aikou Takashi , Mercer Julian F.B. , Akiyama Shin-ichi , Furukawa Tatsuhiko
Published: March 2023

Abstract
We and others have shown that the copper transporters ATP7A and ATP7B play a role in cellular resistance to cis-diaminedichloroplatinum (II) (CDDP). In this study, we found that ATP7A transfection of Chinese hamster ovary cells (CHO-K1) and fibroblasts isolated from Menkes disease patients enhanced resistance not only to CDDP but also to various anticancer drugs, such as vincristine, paclitaxel, 7-ethyl-10-hydroxy-camptothecin (SN-38), etoposide, doxorubicin, mitoxantron, and 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11). ATP7A preferentially localized doxorubicin fluorescence to the Golgi apparatus in contrast to the more intense nuclear staining of doxorubicin in the parental cells. Brefeldin A partially and monensin completely altered the distribution of doxorubicin to the nuclei in the ATP7A-expressing cells. ATP7A expression also enhanced the efflux rates of doxorubicin and SN-38 from cells and increased the uptake of SN-38 in membrane vesicles. These findings strongly suggested that ATP7A confers multidrug resistance to the cells by compartmentalizing drugs in the Golgi apparatus and by enhancing efflux of these drugs, and the trans-Golgi network has an important role of ATP7A-related drug resistance. ATP7A was expressed in 8 of 34 (23.5%) clinical colon cancer specimens but not in the adjacent normal epithelium. Using the histoculture drug response assay that is useful for the prediction of drug sensitivity of clinical cancers, ATP7A-expressing colon cancer cells were significantly more resistant to SN-38 than ATP7A-negative cells. Thus, ATP7A confers resistance to various anticancer agents on cancer cells and might be a good index of drug resistance in clinical colon cancers. [Cancer Res 2007;67(10):4860–7]
Data from Mutant p53 Protects Cells from 12-O-Tetradecanoylphorbol-13-Acetate–Induced Death by Attenuating Activating Transcription Factor 3 Induction
Authors: Buganim Yosef , Kalo Eyal , Brosh Ran , Besserglick Hila , Nachmany Ido , Rais Yoach , Stambolsky Perry , Tang Xiaohu , Milyavsky Michael , Shats Igor , Kalis Marina , Goldfinger Naomi , Rotter Varda
Published: March 2023

Abstract
Mutations in p53 are ubiquitous in human tumors. Some p53 mutations not only result in loss of wild-type (WT) activity but also grant additional functions, termed “gain of function.” In this study, we explore how the status of p53 affects the immediate response gene activating transcription factor 3 (ATF3) in the 12-O-tetradecanoylphorbol-13-acetate (TPA)-protein kinase C (PKC) pathway. We show that high doses of TPA induce ATF3 in a WT p53-independent manner correlating with PKCs depletion and cell death. We show that cells harboring mutant p53 have attenuated ATF3 induction and are less sensitive to TPA-induced death compared with their p53-null counterparts. Mutagenesis analysis of the ATF3 promoter identified the regulatory motifs cyclic AMP-responsive element binding protein/ATF and MEF2 as being responsible for the TPA-induced activation of ATF3. Moreover, we show that mutant p53 attenuates ATF3 expression by two complementary mechanisms. It interacts with the ATF3 promoter and influences its activity via the MEF2 site, and additionally, it attenuates transcriptional expression of the ATF3 activator MEF2D. These data provide important insights into the molecular mechanisms that underlie mutant p53 gain of function. (Cancer Res 2006; 66(22): 1750-9)
Data from Fhit Modulates the DNA Damage Checkpoint Response
Authors: Ishii Hideshi , Mimori Koshi , Inoue Hiroshi , Inageta Taeko , Ishikawa Kazuhiro , Semba Shuho , Druck Teresa , Trapasso Francesco , Tani Kenzaburo , Vecchione Andrea , Croce Carlo M. , Mori Masaki , Huebner Kay
Published: March 2023

Abstract
In preneoplastic lesions, the DNA damage checkpoint is induced and loss of heterozygosity at the FRA3B/FHIT common chromosome fragile region precedes or is coincident with activation of the checkpoint response in these early stages. Introduction of exogenous Fhit into cells in vitro led to modulation of expression of checkpoint proteins Hus1 and Chk1 at mid-S checkpoint, a modulation that led to induction of apoptosis in esophageal cancer cells but not in noncancerous primary cultures. Mutation of the conserved Fhit tyrosine 114 resulted in failure of this function, confirming the importance of this residue. The results suggest that the DNA damage–susceptible FRA3B/FHIT chromosome fragile region, paradoxically, encodes a protein that is necessary for protecting cells from accumulation of DNA damage through its role in modulation of checkpoint proteins, and inactivation of Fhit contributes to accumulation of abnormal checkpoint phenotypes in cancer development. (Cancer Res 2006; 66(23): 11287-92)
Data from Spontaneous and UV Radiation–Induced Multiple Metastatic Melanomas in Cdk4R24C/R24C/TPras Mice
Authors: Hacker Elke , Muller H. Konrad , Irwin Nicole , Gabrielli Brian , Lincoln Douglas , Pavey Sandra , Powell Marianne Broome , Malumbres Marcos , Barbacid Mariano , Hayward Nicholas , Walker Graeme
Published: March 2023

Abstract
Human melanoma susceptibility is often characterized by germ-line inactivating CDKN2A (INK4A/ARF) mutations, or mutations that activate CDK4 by preventing its binding to and inhibition by INK4A. We have previously shown that a single neonatal UV radiation (UVR) dose delivered to mice that carry melanocyte-specific activation of Hras (TPras) increases melanoma penetrance from 0% to 57%. Here, we report that activated Cdk4 cooperates with activated Hras to enhance susceptibility to melanoma in mice. Whereas UVR treatment failed to induce melanomas in Cdk4R24C/R24C mice, it greatly increased the penetrance and decreased the age of onset of melanoma development in Cdk4R24C/R24C/TPras animals compared with TPras alone. This increased penetrance was dependent on the threshold of Cdk4 activation as Cdk4R24C/+/TPras animals did not show an increase in UVR-induced melanoma penetrance compared with TPras alone. In addition, Cdk4R24C/R24C/TPras mice invariably developed multiple lesions, which occurred rarely in TPras mice. These results indicate that germ-line defects abrogating the pRb pathway may enhance UVR-induced melanoma. TPras and Cdk4R24C/R24C/TPras tumors were comparable histopathologically but the latter were larger and more aggressive and cultured cells derived from such melanomas were also larger and had higher levels of nuclear atypia. Moreover, the melanomas in Cdk4R24C/R24C/TPras mice, but not in TPras mice, readily metastasized to regional lymph nodes. Thus, it seems that in the mouse, Hras activation initiates UVR-induced melanoma development whereas the cell cycle defect introduced by mutant Cdk4 contributes to tumor progression, producing more aggressive, metastatic tumors. (Cancer Res 2006; 66(6): 2946-52)
Data from PGP9.5 Methylation in Diffuse-Type Gastric Cancer
Authors: Yamashita Keishi , Park Hannah Lui , Kim Myoung Sook , Osada Motonobu , Tokumaru Yutaka , Inoue Hiroshi , Mori Masaki , Sidransky David
Published: March 2023

Abstract
Diffuse-type gastric cancer (DGC) is the most deadly form of gastric cancer and is frequently accompanied by peritoneal dissemination and metastasis. The specific molecular events involved in DGC pathogenesis remain elusive. Accumulating evidence of epigenetic inactivation in tumor suppressor genes led us to conduct a comprehensive screen to identify novel methylated genes in human cancers using pharmacologic unmasking and subsequent microarray analysis. We compared differential RNA expression profiles of DGC and intestinal-type gastric cancer (IGC) cell lines treated with 5-aza-2′-deoxycytidine using microarrays containing 22,284 genes. We identified 16 methylated genes, including many novel genes, in DGC cell lines and studied PGP9.5 with particular interest. In primary gastric cancers, PGP9.5 was found to be more frequently methylated in DGCs (78%) than in IGCs (36%; DGC versus IGC, P < 0.05). Furthermore, real-time methylation-specific PCR analysis of PGP9.5 showed relatively higher methylation levels in DGC than in IGC. Our data thus implicate a molecular event common in the DGC phenotype compared with IGC. (Cancer Res 2006; 66(7): 3921-7)
Data from Genetic and Epigenetic Analysis of von Hippel-Lindau (VHL) Gene Alterations and Relationship with Clinical Variables in Sporadic Renal Cancer
Authors: Banks Rosamonde E. , Tirukonda Prasanna , Taylor Claire , Hornigold Nick , Astuti Dewi , Cohen Dena , Maher Eamonn R. , Stanley Anthea J. , Harnden Patricia , Joyce Adrian , Knowles Margaret , Selby Peter J.
Published: March 2023

Abstract
Genetic and epigenetic changes in the von Hippel-Lindau (VHL) tumor suppressor gene are common in sporadic conventional renal cell carcinoma (cRCC). Further insight into the clinical significance of these changes may lead to increased biological understanding and identification of subgroups of patients differing prognostically or who may benefit from specific targeted treatments. We have comprehensively examined the VHL status in tissue samples from 115 patients undergoing nephrectomy, including 96 with sporadic cRCC. In patients with cRCC, loss of heterozygosity was found in 78.4%, mutation in 71%, and promoter methylation in 20.4% of samples. Multiplex ligation–dependent probe amplification identified intragenic copy number changes in several samples including two which were otherwise thought to be VHL-noninvolved. Overall, evidence of biallelic inactivation was found in 74.2% of patients with cRCC. Many of the mutations were novel and approximately two-thirds were potentially truncating. Examination of these and other published findings confirmed mutation hotspots affecting codons 117 and 164, and revealed a common region of mutation in codons 60 to 78. Gender-specific differences in methylation and mutation were seen, although not quite achieving statistical significance (P = 0.068 and 0.11), and a possible association between methylation and polymorphism was identified. No significant differences were seen between VHL subgroups with regard to clinicopathologic features including stage, grade, tumor size, cancer-free and overall survival, with the exception of a significant association between loss of heterozygosity and grade, although a possible trend for survival differences based on mutation location was apparent. (Cancer Res 2006; 66(4): 2000-11)
Data from Farnesyl and Geranylgeranyl Transferase Inhibitors Induce G1 Arrest by Targeting the Proteasome
Authors: Efuet Ekem T. , Keyomarsi Khandan
Published: March 2023

Abstract
Isoprenoid inhibitors are being evaluated as agents for the treatment of cancer. Their antitumor activity is attributed to inhibition of post-translational modification of Ras, which is crucial for its translocation and attachment to the plasma membrane, and ultimate involvement in signal transduction. However, whether blocking of Ras is solely responsible for the observed antitumor activity is unresolved. In this report, we propose an alternate mechanism. Using breast tumor models, we show that agents possessing a lactone moiety, including statins (such as lovastatin) and the isoprenoid inhibitors (such as FTI-277 and GGTI-298), mediate their cell cycle inhibitory activities by blocking the chymotrypsin activity of the proteasome in vitro. This results in the accumulation of cyclin-dependent kinase inhibitors p21 and p27 with subsequent G1 arrest. Cells devoid of p21 were refractory to the growth-inhibitory activity of lovastatin, FTI-277, and GGTI-298. However, in these p21 null cells, isoprenylation of key substrates of farnesyl transferase (such as Ras) and of geranylgeranyl transferase (such as RAP-1) were inhibited by FTI-277 and GGTI-298, respectively, suggesting that although both these isoprenoid inhibitors reached and inhibited their intended targets, inhibition of the isoprenylation of Ras and RAP-1A are not sufficient to mediate G1 arrest. We also show that the cell cycle effects can be attributed to the functional lactone moiety of the aforementioned agents. Collectively, our data suggest that FTI and GGTI and other agents containing an active lactone moiety mediate G1 arrest via inhibition of the proteasome and up-regulation of p21, independent of the inhibition of isoprenylation of Ras or RAP-1. (Cancer Res 2006; 66(2): 1040-51)
Data from Multiple Hepatic Receptors Cooperate to Eliminate Secretory Mucins Aberrantly Entering the Bloodstream: Are Circulating Cancer Mucins the “Tip of the Iceberg”?
Authors: Wahrenbrock Mark G. , Varki Ajit
Published: March 2023

Abstract
Hollow organs lined by columnar epithelial cells normally secrete mucins and their proteolytic fragments vectorially into the lumen. These heterogeneously O-glycosylated molecules are known to aberrantly enter the bloodstream in the setting of epithelial carcinomas and possibly during injury or inflammation. We have recently shown that carcinoma mucin fragments can trigger the rapid formation of platelet-rich microthrombi in vivo. Thus, mechanisms to clear such aberrantly secreted mucins must exist. Indeed, we found that i.v. injected carcinoma mucin fragments had an ∼1 minute half-life in mice, which was primarily due to rapid clearance by hepatic reticuloendothelial cells. Inhibition of known glycan-recognizing hepatic clearance receptors showed involvement of multiple partially overlapping clearance systems. Studies of genetically deficient mice and incomplete competition between different mucins confirmed this result. Thus, multiple hepatic clearance receptors cooperate to eliminate secretory mucins entering the circulation, limiting potential pathology. This may also explain why mucin-type clustered O-glycosylation is rare on plasma proteins. Notably, small subsets of injected carcinoma mucins remained unrecognized by clearance systems, had a much longer half-life, and carried highly sialylated O-glycans. Similar circulating mucins were found in tumor-bearing mice despite lack of saturation of hepatic clearance mechanisms. Thus, circulating cancer mucins currently used as clinical diagnostic markers likely represent only the clearance-resistant “tip of the iceberg.” Such aberrantly circulating mucins could play pathologic roles not only in cancer but also during injury or inflammation of hollow organs and in liver disease. (Cancer Res 2006; 66(4): 2433-41)