bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Rapamycin Prevents Early Onset of Tumorigenesis in an Oral-Specific K-ras and p53 Two-Hit Carcinogenesis Model
Authors: Raimondi Ana R. , Molinolo Alfredo , Gutkind J. Silvio
Published: March 2024

Abstract
Head and neck squamous cell carcinomas (HNSCC), the majority of which occur in the oral cavity, remain a significant cause of morbidity and mortality worldwide. A major limitation in HNSCC research has been the paucity of animal models to test the validity of current genetic paradigms of tumorigenesis and to explore the effectiveness of new treatment modalities and chemopreventive strategies. Here, we have developed an inducible oral-specific animal tumor model system, which consists in the expression of a tamoxifen-inducible Cre recombinase (CreERtam) under the control of the cytokeratin 14 (K14) promoter (K14-CreERtam) and mice in which the endogenous K-ras locus is targeted (LSL-K-rasG12D), thereby causing the expression of endogenous levels of oncogenic K-rasG12D following removal of a stop element. Surprisingly, whereas K14-CreERtam can also target the skin, K14-CreERtam/LSL-K-rasG12D mice developed papillomas exclusively in the oral mucosa within 1 month after tamoxifen treatment. These lesions were highly proliferative but never progressed to carcinoma. However, when crossed with p53 conditional knockout (p53flox/flox) mice, mice developed SCCs exclusively on the tongue as early as 2 weeks after tamoxifen induction, concomitant with a remarkable activation of the mammalian target of rapamycin (mTOR) signaling pathway. The availability of this ras and p53 two-hit animal model system recapitulating HNSCC progression may provide a suitable platform for exploring novel molecular targeted approaches for the treatment of this devastating disease. Indeed, we show here that mTOR inhibition by the use of rapamycin is sufficient to halt tumor progression in this genetically defined oral cancer model system, thereby prolonging animal survival. [Cancer Res 2009;69(10):4159–66]
Data from Leptin Receptor–Related Immune Response in Colorectal Tumors: The Role of Colonocytes and Interleukin-8
Authors: Abolhassani Mohammad , Aloulou Nijez , Chaumette Marie Thérèse , Aparicio Thomas , Martin-Garcia Nadine , Mansour Hicham , Le Gouvello Sabine , Delchier Jean Charles , Sobhani Iradj
Published: March 2024

Abstract
We have shown that ObRb, the leptin receptor, is overexpressed in colorectal cancer cells, and that this may influence the patients' outcome. We investigated colonocytes as leptin targets and characterized their pivotal role in antitumor immune response. Cytokine and chemokine mRNAs in HT29 cells were measured by targeted arrays. In vitro, normal colonocytes and human colon cancer cells (HT29, Caco-2, SW480, and HCT116) were used to investigate ObRb transduction system and cytokine releases. Animal colonocytes and CD8 splenocytes and human HT29, HCT116, and CD8+ cells from blood donors were used to investigate the lymphocyte response to the colonocytes when stimulated by leptin. Leptin-induced cytokine releases in the normal colonic mucosa and tumor growth and cytokine releases within tumors in vivo were measured in male rats and nude mice, respectively. Statistical analysis was done by Fisher's exact and Mann-Whitney U tests. Various cytokines and their receptors were produced in normal and tumoral colonocytes in response to leptin by increasing nuclear factor-κB activation. Interleukin-8 (IL-8) was the main cytokine produced in vitro. The levels of IL-8 and its receptor, CXCR1, were higher in tumors than in homologous normal mucosa. Systemic leptin enhanced the proinflammatory cytokines in normal colonocytes and in HT29 xenografted tumor colonocytes. Colonocyte-derived products after leptin treatment stimulated perforin and granzyme B expressions in normal CD8+ T cells in vitro. Leptin triggers an inflammatory response in tumor tissue by directly stimulating colonocytes, which can recruit T cytotoxic cells in the tumor microenvironment. [Cancer Res 2008;68(22):9423–32]
Data from Mutational Inactivation of PTPRD in Glioblastoma Multiforme and Malignant Melanoma
Authors: Solomon David A. , Kim Jung-Sik , Cronin Julia C. , Sibenaller Zita , Ryken Timothy , Rosenberg Steven A. , Ressom Habtom , Jean Walter , Bigner Darell , Yan Hai , Samuels Yardena , Waldman Todd
Published: March 2024

Abstract
An additional tumor suppressor gene on chromosome 9p telomeric to the CDKN2A/B locus has long been postulated to exist. Using Affymetrix 250K single nucleotide polymorphism arrays to screen for copy number changes in glioblastoma multiforme (GBM), we detected a high frequency of deletions of the PTPRD gene, which encodes a receptor protein tyrosine phosphatase at chromosome 9p23-24.1. Missense and nonsense mutations of PTPRD were identified in a subset of the samples lacking deletions, including an inherited mutation with somatic loss of the wild-type allele. We then sequenced the gene in melanoma and identified 10 somatic mutations in 7 of 57 tumors (12%). Reconstitution of PTPRD expression in GBM and melanoma cells harboring deletions or mutations led to growth suppression and apoptosis that was alleviated by both the somatic and constitutional mutations. These data implicate PTPRD in the pathogenesis of tumors of neuroectodermal origin and, when taken together with other recent reports of PTPRD mutations in adenocarcinoma of the colon and lung, suggest that PTPRD may be one of a select group of tumor suppressor genes that are inactivated in a wide range of common human tumor types. [Cancer Res 2008;68(24):10300–6]
Data from Dual Roles for Coactivator Activator and its Counterbalancing Isoform Coactivator Modulator in Human Kidney Cell Tumorigenesis
Authors: Kang Yun Kyoung , Schiff Rachel , Ko Lan , Wang Tao , Tsai Sophia Y. , Tsai Ming-Jer , O'Malley Bert W.
Published: March 2024

Abstract
Coactivator activator (CoAA) has been reported to be a coactivator that regulates steroid receptor–mediated transcription and alternative RNA splicing. Herein, we show that CoAA is a dual-function coregulator that inhibits G1-S transition in human kidney cells and suppresses anchorage-independent growth and xenograft tumor formation. Suppression occurs in part by down-regulating c-myc and its downstream effectors ccnd1 and skp2 and causing accumulation of p27/Kip1 protein. In this cellular setting, CoAA directly represses the proto-oncogene c-myc by recruiting HDAC3 protein and decreasing both the acetylation of histone H3 and the presence of RNA polymerase II on the c-myc promoter. Interestingly, a splicing isoform of CoAA, coactivator modulator (CoAM), antagonizes CoAA-induced G1-S transition and growth inhibition by negatively regulating the mRNA levels of the endogenous CoAA isoform. In addition, we found that expression of CoAA protein is significantly decreased in human renal cell carcinoma compared with normal kidney. Our study presents evidence that CoAA is a potential tumor suppressor in renal carcinoma and that CoAM is a counterbalancing splice isoform. This is, thus far, the only example of a nuclear receptor coregulator involved in suppression of kidney cancer and suggests potentially significant new roles for coregulators in renal cancer biology. [Cancer Res 2008;68(19):7887–96]
Data from Regulation of the Adenomatous Polyposis Coli Gene by the miR-135 Family in Colorectal Cancer
Authors: Nagel Remco , le Sage Carlos , Diosdado Begoña , van der Waal Maike , Oude Vrielink Joachim A.F. , Bolijn Anne , Meijer Gerrit A. , Agami Reuven
Published: March 2024

Abstract
Inactivation of the adenomatous polyposis coli (APC) gene is a major initiating event in colorectal tumorigenesis. Most of the mutations in APC generate premature stop codons leading to truncated proteins that have lost β-catenin binding sites. APC-free β-catenin stimulates the Wnt signaling pathway, leading to active transcription of target genes. In the current study, we describe a novel mechanism for APC regulation. We show that miR-135a&b target the 3′ untranslated region of APC, suppress its expression, and induce downstream Wnt pathway activity. Interestingly, we find a considerable up-regulation of miR-135a&b in colorectal adenomas and carcinomas, which significantly correlated with low APC mRNA levels. This genetic interaction is also preserved in full-blown cancer cell lines expressing miR-135a&b, regardless of the mutational status of APC. Thus, our results uncover a miRNA-mediated mechanism for the control of APC expression and Wnt pathway activity, and suggest its contribution to colorectal cancer pathogenesis. [Cancer Res 2008;68(14):5795–802]
Data from Inhibition of DNA Methyltransferase Activates Tumor Necrosis Factor α–Induced Monocytic Differentiation in Acute Myeloid Leukemia Cells
Authors: Laurenzana Anna , Petruccelli Luca A. , Pettersson Filippa , Figueroa Maria Eugenia , Melnick Ari , Baldwin Albert S. , Paoletti Francesco , Miller Wilson H.
Published: March 2024

Abstract
Transcriptional silencing via promoter methylation of genes important for cell growth and differentiation plays a key role in myeloid leukemogenesis. We find that clinically achievable levels of 5-aza-2′-deoxycytidine (5-AZA-dC), a potent inhibitor of DNA methylation, can modify chromatin and restore the ability of tumor necrosis factor α (TNFα) to induce monocytic differentiation of the acute myeloid leukemia cells NB4 and U937. Although 5-AZA-dC cannot fully induce differentiation, we show that 5-AZA-dC acts directly on TNFα-responsive promoters to facilitate TNFα-induced transcriptional pathways leading to differentiation. 5-AZA-dC regulates the expression of Dif-2, a TNFα target gene, by deacetylating chromatin domains in a methylation-dependent manner. Chromatin immunoprecipitation analyses of the Dif-2 promoter show histone hyperacetylation and a recruitment of the nuclear factor-κB transcription factor in response to 5-AZA-dC. Furthermore, 5-AZA-dC plus TNFα enhances the level of phosphorylated RNA Pol II at the Dif-2 promoter via synergistic recruitment of TFIIH. We conclude that nonspecific changes in chromatin can allow a specific transcriptional inducer to overcome blocks in leukemic cell differentiation. Our results support the concept of low doses of 5-AZA-dC acting in combination with other agents to target epigenetic changes that drive malignant growth in leukemic cells. [Cancer Res 2009;69(1):55–64]
Data from Methylation of Polycomb Target Genes in Intestinal Cancer Is Mediated by Inflammation
Authors: Hahn Maria A. , Hahn Torsten , Lee Dong-Hyun , Esworthy R. Steven , Kim Byung-wook , Riggs Arthur D. , Chu Fong-Fong , Pfeifer Gerd P.
Published: March 2024

Abstract
Epigenetic changes are strongly associated with cancer development. DNA hypermethylation is associated with gene silencing and is often observed in CpG islands. Recently, it was suggested that aberrant CpG island methylation in tumors is directed by Polycomb (PcG) proteins. However, specific mechanisms responsible for methylation of PcG target genes in cancer are not known. Chronic infection and inflammation contribute to up to 25% of all cancers worldwide. Using glutathione peroxidase, Gpx1 and Gpx2, double knockout (Gpx1/2-KO) mice as a model of inflammatory bowel disease predisposing to intestinal cancer, we analyzed genome-wide DNA methylation in the mouse ileum during chronic inflammation, aging, and cancer. We found that inflammation leads to aberrant DNA methylation in PcG target genes, with 70% of the ∼250 genes methylated in the inflamed tissue being PcG targets in embryonic stem cells and 59% of the methylated genes being marked by H3K27 trimethylation in the ileum of adult wild-type mice. Acquisition of DNA methylation at CpG islands in the ileum of Gpx1/2-KO mice frequently correlates with loss of H3K27 trimethylation at the same loci. Inflammation-associated DNA methylation occurs preferentially in tissue-specific silent genes and, importantly, is much more frequently represented in tumors than is age-dependent DNA methylation. Sixty percent of aberrant methylation found in tumors is also present in the inflamed tissue. In summary, inflammation creates a signature of aberrant DNA methylation, which is observed later in the malignant tissue and is directed by the PcG complex. [Cancer Res 2008;68(24):10280–9]
Data from Temozolomide-Mediated Radiosensitization of Human Glioma Cells in a Zebrafish Embryonic System
Authors: Geiger Geoffrey A. , Fu Weili , Kao Gary D.
Published: March 2024

Abstract
The zebrafish (Danio rerio) is a popular vertebrate model for biomedical research. The rapid development, transparency, and experimental accessibility of the embryo offer opportunities for assessing the developmental effects of anticancer treatment strategies. We therefore systematically investigated parameters for growing U251 human glioma cells expressing red fluorescent protein (U251-RFP) in zebrafish embryos. Factors optimized include injection volume, number of cells injected, anatomic site of injection, age of the embryo at the time of injection, and postinjection incubation temperature. After injection into the embryos, the U251-RFP cells proliferated and the resultant tumors, and even individual cells, could be visualized in real-time via fluorescence microscopy without the need for sacrifice. These tumors recruited host zebrafish vasculature, suggesting cancer cell–host tissue interactions. Having optimized parameters for introducing and growing these human cells in the zebrafish embryos, we exposed both embryos and transplanted cancer cells to ionizing radiation and temozolomide, either alone or in combination. The human tumors in each embryo were substantially diminished following exposure to ionizing radiation and the decrease was further enhanced by pretreatment with temozolomide. In contrast, temozolomide had no discernible effects on embryonic development. These results together support the relative safety of temozolomide during embryonic development, as well as its anticancer efficacy when combined with radiation. These results suggest the value of the zebrafish model for in vivo testing of the efficacy and safety of anticancer strategies, especially on the very young. [Cancer Res 2008;68(9):3396–404]
Data from A SNP in a let-7 microRNA Complementary Site in the KRAS 3′ Untranslated Region Increases Non–Small Cell Lung Cancer Risk
Authors: Chin Lena J. , Ratner Elena , Leng Shuguang , Zhai Rihong , Nallur Sunitha , Babar Imran , Muller Roman-Ulrich , Straka Eva , Su Li , Burki Elizabeth A. , Crowell Richard E. , Patel Rajeshvari , Kulkarni Trupti , Homer Robert , Zelterman Daniel , Kidd Kenneth K. , Zhu Yong , Christiani David C. , Belinsky Steven A. , Slack Frank J. , Weidhaas Joanne B.
Published: March 2024

Abstract
Lung cancer is the leading cause of cancer deaths worldwide, yet few genetic markers of lung cancer risk useful for screening exist. The let-7 family-of-microRNAs (miRNA) are global genetic regulators important in controlling lung cancer oncogene expression by binding to the 3′ untranslated regions of their target mRNAs. The purpose of this study was to identify single nucleotide polymorphisms (SNP) that could modify let-7 binding and to assess the effect of such SNPs on target gene regulation and risk for non–small cell lung cancer (NSCLC). let-7 complementary sites (LCS) were sequenced in the KRAS 3′ untranslated region from 74 NSCLC cases to identify mutations and SNPs that correlated with NSCLC. The allele frequency of a previously unidentified SNP at LCS6 was characterized in 2,433 people (representing 46 human populations). The frequency of the variant allele is 18.1% to 20.3% in NSCLC patients and 5.8% in world populations. The association between the SNP and the risk for NSCLC was defined in two independent case-control studies. A case-control study of lung cancer from New Mexico showed a 2.3-fold increased risk (confidence interval, 1.1–4.6; P = 0.02) for NSCLC cancer in patients who smoked <40 pack-years. This association was validated in a second independent case-control study. Functionally, the variant allele results in KRAS overexpression in vitro. The LCS6 variant allele in a KRAS miRANA complementary site is significantly associated with increased risk for NSCLC among moderate smokers and represents a new paradigm for let-7 miRNAs in lung cancer susceptibility. [Cancer Res 2008;68(20):8535–40]
Data from Regulation of Estrogen-Dependent Transcription by the LIM Cofactors CLIM and RLIM in Breast Cancer
Authors: Johnsen Steven A. , Güngör Cenap , Prenzel Tanja , Riethdorf Sabine , Riethdorf Lutz , Taniguchi-Ishigaki Naoko , Rau Thomas , Tursun Baris , Furlow J. David , Sauter Guido , Scheffner Martin , Pantel Klaus , Gannon Frank , Bach Ingolf
Published: March 2024

Abstract
Mammary oncogenesis is profoundly influenced by signaling pathways controlled by estrogen receptor α (ERα). Although it is known that ERα exerts its oncogenic effect by stimulating the proliferation of many human breast cancers through the activation of target genes, our knowledge of the underlying transcriptional mechanisms remains limited. Our published work has shown that the in vivo activity of LIM homeodomain transcription factors (LIM-HD) is critically regulated by cofactors of LIM-HD proteins (CLIM) and the ubiquitin ligase RING finger LIM domain-interacting protein (RLIM). Here, we identify CLIM and RLIM as novel ERα cofactors that colocalize and interact with ERα in primary human breast tumors. We show that both cofactors associate with estrogen-responsive promoters and regulate the expression of endogenous ERα target genes in breast cancer cells. Surprisingly, our results indicate opposing functions of LIM cofactors for ERα and LIM-HDs: whereas CLIM enhances transcriptional activity of LIM-HDs, it inhibits transcriptional activation mediated by ERα on most target genes in vivo. In turn, the ubiquitin ligase RLIM inhibits transcriptional activity of LIM-HDs but enhances transcriptional activation of endogenous ERα target genes. Results from a human breast cancer tissue microarray of 1,335 patients revealed a highly significant correlation of elevated CLIM levels to ER/progesterone receptor positivity and poor differentiation of tumors. Combined, these results indicate that LIM cofactors CLIM and RLIM regulate the biological activity of ERα during the development of human breast cancer. [Cancer Res 2009;69(1):128–36]
Data from Deleted in Liver Cancer 1 Controls Cell Migration through a Dia1-Dependent Signaling Pathway
Authors: Holeiter Gerlinde , Heering Johanna , Erlmann Patrik , Schmid Simone , Jähne Ruth , Olayioye Monilola A.
Published: March 2024

Abstract
Deleted in liver cancer (DLC) 1 and 2 are Rho GTPase-activating proteins that are frequently down-regulated in various types of cancer. Ectopic expression in carcinoma cell lines lacking these proteins has been shown to inhibit cell migration and invasion. However, whether the loss of DLC1 or DLC2 is the cause of aberrant Rho signaling in transformed cells has not been investigated. Here, we have down-regulated DLC1 and DLC2 expression in breast cancer cells using a RNA interference approach. Silencing of DLC1 led to the stabilization of stress fibers and focal adhesions and enhanced cell motility in wound-healing as well as chemotactic Transwell assays. We provide evidence that enhanced migration of cells lacking DLC1 is dependent on the Rho effector protein Dia1 but does not require the activity of Rho kinase. By contrast, DLC2 knockdown failed to affect the migratory behavior of cells, suggesting that the two proteins have distinct functions. This is most likely due to their differential subcellular localizations, with DLC1 found in focal adhesions and DLC2 being mainly cytosolic. Collectively, our data show that DLC1 is critically involved in the control of Rho signaling and actin cytoskeleton remodeling and that its cellular loss is sufficient for the acquisition of a more migratory phenotype of breast cancer cells. [Cancer Res 2008;68(21):8743–51]
Data from Vitamin C Antagonizes the Cytotoxic Effects of Antineoplastic Drugs
Authors: Heaney Mark L. , Gardner Jeffrey R. , Karasavvas Nicos , Golde David W. , Scheinberg David A. , Smith Emily A. , O'Connor Owen A.
Published: March 2024

Abstract
Vitamin C is an antioxidant vitamin that has been hypothesized to antagonize the effects of reactive oxygen species–generating antineoplastic drugs. The therapeutic efficacy of the widely used antineoplastic drugs doxorubicin, cisplatin, vincristine, methotrexate, and imatinib were compared in leukemia (K562) and lymphoma (RL) cell lines with and without pretreatment with dehydroascorbic acid, the commonly transported form of vitamin C. The effect of vitamin C on viability, clonogenicity, apoptosis, P-glycoprotein, reactive oxygen species (ROS), and mitochondrial membrane potential was determined. Pretreatment with vitamin C caused a dose-dependent attenuation of cytotoxicity, as measured by trypan blue exclusion and colony formation after treatment with all antineoplastic agents tested. Vitamin C given before doxorubicin treatment led to a substantial reduction of therapeutic efficacy in mice with RL cell–derived xenogeneic tumors. Vitamin C treatment led to a dose-dependent decrease in apoptosis in cells treated with the antineoplastic agents that was not due to up-regulation of P-glycoprotein or vitamin C retention modulated by antineoplastics. Vitamin C had only modest effects on intracellular ROS and a more general cytoprotective profile than N-acetylcysteine, suggesting a mechanism of action that is not mediated by ROS. All antineoplastic agents tested caused mitochondrial membrane depolarization that was inhibited by vitamin C. These findings indicate that vitamin C given before mechanistically dissimilar antineoplastic agents antagonizes therapeutic efficacy in a model of human hematopoietic cancers by preserving mitochondrial membrane potential. These results support the hypothesis that vitamin C supplementation during cancer treatment may detrimentally affect therapeutic response. [Cancer Res 2008;68(19):8031–8]
Data from In vivo Dynamics of Stable Chronic Lymphocytic Leukemia Inversely Correlate with Somatic Hypermutation Levels and Suggest No Major Leukemic Turnover in Bone Marrow
Authors: van Gent Rogier , Kater Arnon P. , Otto Sigrid A. , Jaspers A. , Borghans José A.M. , Vrisekoop Nienke , Ackermans Mariëtte A.T. , Ruiter An F.C. , Wittebol Shulamiet , Eldering Eric , van Oers Marinus H.J. , Tesselaar Kiki , Kersten Marie José , Miedema Frank
Published: March 2024

Abstract
Although accumulating evidence indicates that chronic lymphocytic leukemia (CLL) is a disease with appreciable cell dynamics, it remains uncertain whether this also applies to patients with stable disease. In this study, 2H2O was administered to a clinically homogeneous cohort of nine stable, untreated CLL patients. CLL dynamics in blood and bone marrow were determined and compared with normal B-cell dynamics in blood from five healthy individuals who underwent a similar 2H2O labeling protocol. Average CLL turnover rates (0.08–0.35% of the clone per day) were ∼2-fold lower than average B-cell turnover rates from healthy individuals (0.34–0.89%), whereas the rate at which labeled CLL cells in blood disappeared (0.00–0.39% of B cells per day) was ∼10-fold lower compared with labeled B cells from healthy individuals (1.57–4.24% per day). Leukemic cell turnover variables inversely correlated with the level of somatic hypermutation of the CLL clone (IgVH mutations). Although CLL cells in bone marrow had a higher level of label enrichment than CLL cells in blood, no difference between proliferation rates and proapoptotic and antiapoptotic profiles of CLL cells from these compartments was observed. These data suggest that, in stable disease, there is a biological relationship between the degree of somatic hypermutation of the CLL clone and its dynamics in vivo. Furthermore, in contrast to lymph nodes, the bone marrow does not seem to be a major CLL proliferation site. [Cancer Res 2008;68(24):10137–44]
Data from Utilization of Pathway Signatures to Reveal Distinct Types of B Lymphoma in the Eμ-myc Model and Human Diffuse Large B-Cell Lymphoma
Authors: Mori Seiichi , Rempel Rachel E. , Chang Jeffrey T. , Yao Guang , Lagoo Anand S. , Potti Anil , Bild Andrea , Nevins Joseph R.
Published: March 2024

Abstract
The Eμ-myc transgenic mouse has provided a valuable model for the study of B-cell lymphoma. Making use of gene expression analysis and, in particular, expression signatures of cell signaling pathway activation, we now show that several forms of B lymphoma can be identified in the Eμ-myc mice associated with time of tumor onset. Furthermore, one form of Eμ-myc tumor with pre-B character is shown to resemble human Burkitt lymphoma, whereas others exhibit more differentiated B-cell characteristics and show similarity with human diffuse large B-cell lymphoma in the pattern of gene expression, as well as oncogenic pathway activation. Importantly, we show that signatures of oncogenic pathway activity provide further dissection of the spectrum of diffuse large B-cell lymphoma, identifying a subset of patients who have very poor prognosis and could benefit from more aggressive or novel therapeutic strategies. Taken together, these studies provide insight into the complexity of the oncogenic process and a novel strategy for dissecting the heterogeneity of B lymphoma. [Cancer Res 2008;68(20):8525–34]
Data from BRCA1-Associated Protein 1 Interferes with BRCA1/BARD1 RING Heterodimer Activity
Authors: Nishikawa Hiroyuki , Wu Wenwen , Koike Ayaka , Kojima Ryoko , Gomi Hiromichi , Fukuda Mamoru , Ohta Tomohiko
Published: March 2024

Abstract
The breast and ovarian tumor suppressor BRCA1 constitutes a RING heterodimer E3 ligase with BARD1. BRCA1-associated protein 1 (BAP1) is a ubiquitin COOH-terminal hydrolase that was initially identified as a protein that bound to the RING finger domain of BRCA1. However, how BAP1 contributes to the E3 activity of BRCA1/BARD1 is unclear. Here, we report that BAP1 interacts with BARD1 to inhibit the E3 ligase activity of BRCA1/BARD1. Domains comprised by residues 182-365 of BAP1 interact with the RING finger domain of BARD1, and surface plasmon resonance spectroscopy (BIAcore) analyses showed that BAP1 interferes with the BRCA1/BARD1 association. The perturbation resulted in inhibition of BRCA1 autoubiquitination and NPM1/B23 ubiquitination by BRCA1/BARD1. Although BAP1 was capable of deubiquitinating the polyubiquitin chains mediated by BRCA1/BARD1 in vitro, a catalytically inactive mutant of BAP1, C91S, still inhibited the ubiquitination in vitro and in vivo, implicating a second mechanism of action. Importantly, inhibition of BAP1 expression by short hairpin RNA resulted in hypersensitivity of the cells to ionizing irradiation and in retardation of S-phase progression. Together, these results suggest that BAP1 and BRCA1/BARD1 coordinately regulate ubiquitination during the DNA damage response and the cell cycle. [Cancer Res 2009;69(1):111–9]
Data from MicroRNA-21 Targets a Network of Key Tumor-Suppressive Pathways in Glioblastoma Cells
Authors: Papagiannakopoulos Thales , Shapiro Alice , Kosik Kenneth S.
Published: March 2024

Abstract
MicroRNA dysregulation is observed in different types of cancer. MiR-21 up-regulation has been reported for the majority of cancers profiled to date; however, knowledge is limited on the mechanism of action of miR-21, including identification of functionally important targets that contribute to its proproliferative and antiapoptotic actions. In this study, we show for the first time that miR-21 targets multiple important components of the p53, transforming growth factor-β (TGF-β), and mitochondrial apoptosis tumor-suppressive pathways. Down-regulation of miR-21 in glioblastoma cells leads to derepression of these pathways, causing repression of growth, increased apoptosis, and cell cycle arrest. These phenotypes are dependent on two of the miR-21 targets validated in this study, HNRPK and TAp63. These findings establish miR-21 as an important oncogene that targets a network of p53, TGF-β, and mitochondrial apoptosis tumor suppressor genes in glioblastoma cells. [Cancer Res 2008;68(19):8164–72]
Data from Kinetic Stabilization of Microtubule Dynamics by Estramustine Is Associated with Tubulin Acetylation, Spindle Abnormalities, and Mitotic Arrest
Authors: Mohan Renu , Panda Dulal
Published: March 2024

Abstract
Estramustine (EM) alone or in combination with other anticancer agents is clinically used for the treatment of hormone refractory prostate cancer. Furthermore, EM has been shown to potently inhibit the proliferation of different types of cancer cells in culture apparently by targeting microtubules; however, the antiproliferative mechanism of action of EM is not clear. In this work, we have shown that EM strongly suppressed the dynamic instability of individual microtubules in MCF-7 cells by reducing the rates of growing and shortening excursions and increasing the time microtubule spent in the pause state. At its half maximal proliferation inhibitory concentration (IC50), EM exerted strong suppressive effects on the dynamics of microtubules in MCF-7 cells without detectably affecting either the organization or the polymerized mass of microtubules. At relatively high concentrations (5 × IC50), EM significantly depolymerized microtubules in the cells. Furthermore, the microtubules were found highly acetylated, supporting the conclusion that they were stabilized by the drug. EM treatment induced spindle abnormalities in MCF-7 cells, and a major population of the arrested mitotic cells was multipolar. EM also perturbed the microtubule-kinetochore interaction, thereby activating the spindle assembly checkpoint and leading to apoptotic cell death. [Cancer Res 2008;68(15):6181–9]
Data from Somatostatin Receptor sst2 Decreases Cell Viability and Hormonal Hypersecretion and Reverses Octreotide Resistance of Human Pituitary Adenomas
Authors: Acunzo Julie , Thirion Sylvie , Roche Catherine , Saveanu Alexandru , Gunz Ginette , Germanetti Anne Laure , Couderc Bettina , Cohen Richard , Figarella-Branger Dominique , Dufour Henry , Brue Thierry , Enjalbert Alain , Barlier Anne
Published: March 2024

Abstract
In human somatotroph adenomas, growth hormone (GH) hypersecretion can be inhibited by somatostatin analogues such as octreotide. Unfortunately, serum GH levels reach normal values in only 60% of treated patients. The decreased sensitivity to octreotide is strongly related to a lower expression of somatostatin receptor sst2. In this present study, the sst2 gene was transferred by an adenoviral vector (Ad-sst2) in human somatotroph (n = 7) and lactotroph (n = 2) adenomas in vitro. Sst2 mRNA levels and sst2 immunostaining dramatically increased after infection. Ten days after infection at 20 multiplicity of infection (MOI), sst2 gene transfer decreased cell viability from 19% to 90% by caspase-dependent apoptosis. At low viral doses (5 MOI), Ad-sst2 decreased GH or prolactin (PRL) basal secretion and mRNA expression. Somatotroph tumors were classified in three groups according to their octreotide sensitivity. Four days after infection by 5 MOI Ad-sst2, the maximal GH suppression by octreotide increased from 31% to 57% in the octreotide partially resistant group and from 0% to 27% in the resistant ones. In the octreotide-sensitive group, EC50 values significantly decreased from 1.3 × 10−11 to 6.6 × 10−13 mol/L without improving maximal GH suppression. Finally, lactotroph tumors, nonresponding to octreotide in basal conditions, became octreotide sensitive with a maximal PRL suppression of 43% at 10−8 mol/L. Therefore, sst2 reexpression is able to improve octreotide sensitivity. Sst2 gene transfer may open new theapeutic strategies in treatment combined with somatostatin analogues. [Cancer Res 2008;68(24):10163–70]
Data from Agglomerative Epigenetic Aberrations Are a Common Event in Human Breast Cancer
Authors: Novak Petr , Jensen Taylor , Oshiro Marc M. , Watts George S. , Kim Christina J. , Futscher Bernard W.
Published: March 2024

Abstract
Changes in DNA methylation patterns are a common characteristic of cancer cells. Recent studies suggest that DNA methylation affects not only discrete genes, but it can also affect large chromosomal regions, potentially leading to LRES. It is unclear whether such long-range epigenetic events are relatively rare or frequent occurrences in cancer. Here, we use a high-resolution promoter tiling array approach to analyze DNA methylation in breast cancer specimens and normal breast tissue to address this question. We identified 3,506 cancer-specific differentially methylated regions (DMR) in human breast cancer with 2,033 being hypermethylation events and 1,473 hypomethylation events. Most of these DMRs are recurrent in breast cancer; 90% of the identified DMRs occurred in at least 33% of the samples. Interestingly, we found a nonrandom spatial distribution of aberrantly methylated regions across the genome that showed a tendency to concentrate in relatively small genomic regions. Such agglomerates of hypermethylated and hypomethylated DMRs spanned up to several hundred kilobases and were frequently found at gene family clusters. The hypermethylation events usually occurred in the proximity of the transcription start site in CpG island promoters, whereas hypomethylation events were frequently found in regions of segmental duplication. One example of a newly discovered agglomerate of hypermethylated DMRs associated with gene silencing in breast cancer that we examined in greater detail involved the protocadherin gene family clusters on chromosome 5 (PCDHA, PCDHB, and PCDHG). Taken together, our results suggest that agglomerative epigenetic aberrations are frequent events in human breast cancer. [Cancer Res 2008;68(20):8616–25]
Data from The Mechanisms of Differential Sensitivity to an Insulin-like Growth Factor-1 Receptor Inhibitor (BMS-536924) and Rationale for Combining with EGFR/HER2 Inhibitors
Authors: Huang Fei , Greer Ann , Hurlburt Warren , Han Xia , Hafezi Rameh , Wittenberg Gayle M. , Reeves Karen , Chen Jiwen , Robinson Douglas , Li Aixin , Lee Francis Y. , Gottardis Marco M. , Clark Edwin , Helman Lee , Attar Ricardo M. , Dongre Ashok , Carboni Joan M.
Published: March 2024

Abstract
Overexpression and enhanced activity of insulin-like growth factor-I receptor (IGF-IR) in diverse tumor types make it an attractive target for cancer therapy. BMS-536924 is a potent small molecule inhibitor of IGF-IR, which shows antitumor activity in multiple tumor models, including sarcoma. To facilitate the development of IGF-IR inhibitors as cancer therapy, identification of biomarkers for selecting patients most likely to derive clinical benefit is needed. To do so, 28 sarcoma and neuroblastoma cell lines were screened for in vitro response to BMS-536924 to identify sensitive and resistant cell lines. Notably, Ewing's sarcoma, rhabdomyosarcoma, and neuroblastoma are more responsive to BMS-536924, suggesting these specific subtypes may represent potential targeted patient subpopulations for the IGF-IR inhibitor. Gene expression and protein profiling were performed on these cell lines, and candidate biomarkers correlating with intrinsic and/or acquired resistance to BMS-536924 were identified. IGF-I, IGF-II, and IGF-IR were highly expressed in sensitive cell lines, whereas IGFBP-3 and IGFBP-6 were highly expressed in resistant lines. Overexpression of epidermal growth factor receptor (EGFR) and its ligands in resistant cell lines may represent one possible resistance mechanism by the adaptation of IGF-IR–independent growth using alternative signaling pathways. Based on cross-talk between IGF-IR and EGFR pathways, combination studies to target both pathways were performed, and enhanced inhibitory activities were observed. These results provide a strategy for testing combinations of IGF-IR inhibitors with other targeted therapies in clinical studies to achieve improved patient outcomes. Further exploration of mechanisms for intrinsic and acquired drug resistance by these preclinical studies may lead to more rationally designed drugs that target multiple pathways for enhanced antitumor efficacy. [Cancer Res 2009;69(1):161–70]
Data from Characterization of the Recurrent 8p11-12 Amplicon Identifies PPAPDC1B, a Phosphatase Protein, as a New Therapeutic Target in Breast Cancer
Authors: Bernard-Pierrot Isabelle , Gruel Nadège , Stransky Nicolas , Vincent-Salomon Anne , Reyal Fabien , Raynal Virginie , Vallot Céline , Pierron Gaëlle , Radvanyi François , Delattre Olivier
Published: March 2024

Abstract
The 8p11-12 chromosome region is one of the regions most frequently amplified in breast carcinoma (10–15% of cases). Several genes within this region have been identified as candidate oncogenes, as they are both amplified and overexpressed. However, very few studies have explored the role of these genes in cell transformation, with the aim of identifying valuable therapeutic targets. An analysis of comparative genomic hybridization array and expression profiling data for a series of 152 ductal breast carcinomas and 21 cell lines identified five genes (LSM1, BAG4, DDHD2, PPAPDC1B, and WHSC1L1) within the amplified region as consistently overexpressed due to an increased gene copy number. The use of small interfering RNA to knock down the expression of each of these genes showed the major role played by two genes, PPAPDC1B and WHSC1L1, in regulating the survival and transformation of two different cell lines harboring the 8p amplicon. The role of these two genes in cell survival and cell transformation was also confirmed by long-term knockdown expression studies using short hairpin RNAs. The potential of PPAPDC1B, which encodes a transmembrane phosphatase, as a therapeutic target was further shown by the strong inhibition of growth of breast tumor xenografts displaying 8p11-12 amplification induced by the silencing of PPAPDC1B. The oncogenic properties of PPAPDC1B were further shown by its ability to transform NIH-3T3 fibroblasts, inducing their anchorage-independent growth. Finally, microarray experiments on PPAPDC1B knockdown indicated that this gene interfered with multiple cell signaling pathways, including the Janus-activated kinase-signal transducer and activator of transcription, mitogen-activated protein kinase, and protein kinase C pathways. PPAPDC1B may also potentiate the estrogen receptor pathway by down-regulating DUSP22. [Cancer Res 2008;68(17):7165–75]
Data from Identification of Secreted Proteins that Mediate Cell-Cell Interactions in an In vitro Model of the Lung Cancer Microenvironment
Authors: Zhong Li , Roybal Jonathon , Chaerkady Raghothama , Zhang Wan , Choi Kuicheon , Alvarez Cristina A. , Tran Hai , Creighton Chad J. , Yan Shaoyu , Strieter Robert M. , Pandey Akhilesh , Kurie Jonathan M.
Published: March 2024

Abstract
Non–small cell lung cancer (NSCLC) cells with somatic mutations in K-ras recruit to the tumor a variety of cell types (hereafter collectively termed “stromal cells”) that can promote or inhibit tumorigenesis by mechanisms that have not been fully elucidated. Here, we postulated that stromal cells in the tumor microenvironment alter the tumor cell secretome, including those proteins required for tumor growth and dissemination, and we developed an in vitro model to test this hypothesis. Coculturing a murine K-ras mutant lung adenocarcinoma cell line (LKR-13) with a murine lung stromal cell (macrophage, endothelial cell, or fibroblast) enhanced stromal cell migration, induced endothelial tube formation, increased LKR-13 cell proliferation, and regulated the secretion of proteins involved in angiogenesis, inflammation, cell proliferation, and epithelial-to-mesenchymal transition. Among these proteins, CXCL1 has been reported to promote NSCLC development, whereas interleukin-18 (IL-18) has an undefined role. Genetic and pharmacologic strategies to inhibit CXCL1 and IL-18 revealed that stromal cell migration, LKR-13 cell proliferation, and LKR-13 cell tumorigenicity required one or both of these proteins. We conclude that stromal cells enhanced LKR-13 cell tumorigenicity partly through their effects on the secretome of LKR-13 cells. Strategies to inhibit tumor/stromal cell interactions may be useful as therapeutic approaches in NSCLC patients. [Cancer Res 2008;68(17):7237–45]
Data from BCR/ABL Inhibits Mismatch Repair to Protect from Apoptosis and Induce Point Mutations
Authors: Stoklosa Tomasz , Poplawski Tomasz , Koptyra Mateusz , Nieborowska-Skorska Margaret , Basak Grzegorz , Slupianek Artur , Rayevskaya Marina , Seferynska Ilona , Herrera Larry , Blasiak Janusz , Skorski Tomasz
Published: March 2024

Abstract
BCR/ABL kinase–positive chronic myelogenous leukemia (CML) cells display genomic instability leading to point mutations in various genes including bcr/abl and p53, eventually causing resistance to imatinib and malignant progression of the disease. Mismatch repair (MMR) is responsible for detecting misincorporated nucleotides, resulting in excision repair before point mutations occur and/or induction of apoptosis to avoid propagation of cells carrying excessive DNA lesions. To assess MMR activity in CML, we used an in vivo assay using the plasmid substrate containing enhanced green fluorescent protein (EGFP) gene corrupted by T:G mismatch in the start codon; therefore, MMR restores EGFP expression. The efficacy of MMR was reduced ∼2-fold in BCR/ABL-positive cell lines and CD34+ CML cells compared with normal counterparts. MMR was also challenged by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), which generates O6-methylguanine and O4-methylthymine recognized by MMR system. Impaired MMR activity in leukemia cells was associated with better survival, accumulation of p53 but not of p73, and lack of activation of caspase 3 after MNNG treatment. In contrast, parental cells displayed accumulation of p53, p73, and activation of caspase 3, resulting in cell death. Ouabain-resistance test detecting mutations in the Na+/K+ ATPase was used to investigate the effect of BCR/ABL kinase–mediated inhibition of MMR on mutagenesis. BCR/ABL-positive cells surviving the treatment with MNNG displayed ∼15-fold higher mutation frequency than parental counterparts and predominantly G:C→A:T and A:T→G:C mutator phenotype typical for MNNG-induced unrepaired lesions. In conclusion, these results suggest that BCR/ABL kinase abrogates MMR activity to inhibit apoptosis and induce mutator phenotype. [Cancer Res 2008;68(8):2576–80]
Data from Loss of Integrin α1β1 Ameliorates Kras-Induced Lung Cancer
Authors: Macias-Perez Ines , Borza Corina , Chen Xiwu , Yan Xuexian , Ibanez Raquel , Mernaugh Glenda , Matrisian Lynn M. , Zent Roy , Pozzi Ambra
Published: March 2024

Abstract
The collagen IV binding receptor integrin α1β1 has been shown to regulate lung cancer due to its proangiogenic properties; however, it is unclear whether this receptor also plays a direct role in promoting primary lung tumors. To investigate this possibility, integrin α1-null mice were crossed with KrasLA2 mice that carry an oncogenic mutation of the Kras gene (G12D) and develop spontaneous primary tumors with features of non–small cell lung cancer. We provide evidence that KrasLA2/α1-null mice have a decreased incidence of primary lung tumors and longer survival compared with KrasLA2/α1 wild-type controls. Tumors from KrasLA2/α1-null mice were also smaller, less vascularized, and exhibited reduced cell proliferation and increased apoptosis, as determined by proliferating cell nuclear antigen and terminal deoxynucleotidyl-transferase–mediated dUTP nick-end staining, respectively. Moreover, tumors from the KrasLA2/α1-null mice showed diminished extracellular signal-regulated kinase (ERK) but enhanced p38 mitogen-activated protein kinase activation. Primary lung tumor epithelial cells isolated from KrasLA2/α1-null mice showed a significant decrease in anchorage-independent colony formation, collagen-mediated cell proliferation, ERK activation, and, most importantly, tumorigenicity when injected into nude mice compared with KrasLA2/α1 wild-type tumor cells. These results indicate that loss of the integrin α1 subunit decreases the incidence and growth of lung epithelial tumors initiated by oncogenic Kras, suggesting that both Kras and integrin α1β1 cooperate to drive the growth of non–small cell lung cancer in vivo. [Cancer Res 2008;68(15):6127–35]
Data from Sprouty2 Association with B-Raf Is Regulated by Phosphorylation and Kinase Conformation
Authors: Brady Suzanne C. , Coleman Mathew L. , Munro June , Feller Stephan M. , Morrice Nicolas A. , Olson Michael F.
Published: March 2024

Abstract
Sprouty2 is a feedback regulator that controls the Ras/Raf/MEK/extracellular signal-regulated kinase mitogen-activated protein kinase (MAPK) pathway at multiple levels, one way being through direct interaction with Raf kinases. Consistent with a role as a tumor suppressor, Sprouty2 expression is often down-regulated in human cancers. However, Sprouty2 is up-regulated in some cancers, suggesting the existence of posttranscriptional mechanisms that permit evasion of Sprouty2-mediated antitumorigenic properties. We report that MAPK activation induces Sprouty2 phosphorylation on six serine residues, which reduced Sprouty2 association with wild-type B-Raf. Mutation of these six serines to nonphosphorylatable alanines increased the ability of Sprouty2 to inhibit growth factor–induced MAPK activation. Oncogenic B-Raf mutants such as B-Raf V600E did not associate with Sprouty2, but this resistance to Sprouty2 binding was not due to phosphorylation. Instead, the active kinase conformation induced by oncogenic mutation prevents Sprouty2 binding. These results reveal a dual mechanism that affects the Sprouty2/B-Raf interaction: Sprouty phosphorylation and B-Raf conformation. [Cancer Res 2009;69(17):6773–81]
Data from Overexpression of Platelet-Derived Growth Factor-BB Increases Tumor Pericyte Content via Stromal-Derived Factor-1α/CXCR4 Axis
Authors: Song Nan , Huang Yujie , Shi Hubing , Yuan Shaopeng , Ding Yanping , Song Xiaomin , Fu Yan , Luo Yongzhang
Published: March 2024

Abstract
Platelet-derived growth factor-BB (PDGF-BB) is a well-characterized growth factor displaying potent biological effects on angiogenesis. Recent studies reveal that overexpression of PDGF-BB within tumors results in increased pericyte coverage, suggesting that PDGF-BB signaling is also essential for the cancerous pericyte recruitment process. However, the molecular mechanism underlying this regulation remains obscure. In the current study, we show that tumor-derived PDGF-BB induces SDF-1α expression in endothelial cells (EC), resulting in the formation of SDF-1α chemotaxis gradient, which coincides with the PDGF-BB–induced pericyte recruitment during angiogenesis. PDGF-BB dramatically up-regulates SDF-1α secretion through the activation of PDGFRβ in tumor-associated ECs, whereas this up-regulation can be substantially inhibited by either blockade of the phosphatidylinositol 3-kinase/Akt/mTOR pathway with chemical inhibitors or the inactivation of HIF-1α through small interfering RNA interference. On the other hand, we reveal that SDF-1α can increase pericytes motility in vitro. Blockade of the SDF-1α/CXCR4 axis prevents the PDGF-BB–induced pericyte recruitment not only in three in vitro recruitment models but also in the PDGF-BB–overexpressing tumor xenograft models. These results highlight that the involvement of SDF-1α/CXCR4 axis is essential for the pericyte recruitment within the PDGF-BB–overexpressing tumors and raise the possibility that blockade of the SDF-1α/CXCR4 axis may provide a therapeutic synergy with antiangiogenic molecules that selectively target ECs. [Cancer Res 2009;69(15):6057–64]