bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Triggering Senescence Programs Suppresses Chk1 Kinase and Sensitizes Cells To Genotoxic Stresses
Authors: Gabai Vladimir L. , O'Callaghan-Sunol Cornelia , Meng Le , Sherman Michael Y. , Yaglom Julia
Published: March 2024

Abstract
Depletion of the major heat shock protein Hsp72 leads to activation of the senescence program in a variety of tumor cell lines via both p53-dependent and p53-independent pathways. Here, we found that the Hsp72-depleted cells show defect in phosphorylation and activation of the protein kinase Chk1 by genotoxic stresses, such as UVC irradiation or camptothecin. Under these conditions, phosphorylation of Rad17 was also suppressed, whereas phosphorylation of p53 at Ser15 was not affected, indicating a specific defect in phosphorylation of a subset of the ATR kinase substrates. Similarly, suppression of Chk1 activation was seen when senescence signaling was triggered by direct stimulation of p53, depletion of Cdc2, or overexpression of the cell cycle inhibitors p21 or p16. Thus, defect in Chk1 activation was not a consequence of the chaperone imbalance, but rather a downstream effect of activation of the senescence signaling. Inhibition of Chk1 was associated with inefficient inter-S phase checkpoint, as Hsp72 depleted cells failed to halt cell cycle progression upon UVC irradiation. Accordingly, sensitivity of cells to genotoxic stimuli after Hsp72 depletion was significantly enhanced. Thus, activation of the senescence signaling causes a defect in the DNA damage response manifested in increased sensitivity to genotoxic stresses. [Cancer Res 2008;68(6):1834–42]
Data from GM1 and Tumor Necrosis Factor-α, Overexpressed in Renal Cell Carcinoma, Synergize to Induce T-Cell Apoptosis
Authors: Das Tanya , Sa Gaurisankar , Hilston Cynthia , Kudo Daisuke , Rayman Patricia , Biswas Kaushik , Molto Luis , Bukowski Ronald , Rini Brian , Finke James H. , Tannenbaum Charles
Published: March 2024

Abstract
The ability to induce T-cell apoptosis is one mechanism by which tumors evade the immune system, although the molecules involved remain controversial. We found that renal cell carcinoma (RCC)–induced T-cell apoptosis was inhibited by >50% when cocultures were performed with ganglioside-depleted tumor cells, caspase-8–negative lymphocytes, or anti–tumor necrosis factor-α (TNFα) antibodies, suggesting that tumor gangliosides synergize with signals delivered through TNFα death receptors to mediate T-cell killing. The synergy between tumor-derived TNFα and the RCC-overexpressed ganglioside GM1 for killing resting T cells is corroborated by studies using purified GM1 and rTNFα, which indicate that a 48-hour pretreatment with the ganglioside optimally sensitizes the lymphocytes to a TNFα-induced apoptotic death. However, activated T cells, which synthesize TNFα themselves, can be killed by exogenous GM1 alone. RelA-overexpressing lymphocytes are protected from GM1 plus TNFα-mediated apoptosis, a finding consistent with our previous studies indicating that gangliosides inhibit nuclear factor-κB activation. These results are clinically relevant because, similar to T-cells cocultured with GM1-overexpressing RCC lines, T cells isolated from the peripheral blood of patients with metastatic RCC are also heavily coated with that tumor-shed ganglioside. This population of patient cells, unlike T cells isolated from normal donors, is highly susceptible to apoptosis induced by rTNFα or by metastatic patient sera, which contain elevated levels of the cytokine. This report thus extends our previous studies by demonstrating that tumor-derived TNFα enhances RCC apoptogenicity not only by inducing ganglioside synthesis but also by initiating receptor-dependent apoptosis in T cells in which the nuclear factor-κB activation pathway has been inhibited by GM1. [Cancer Res 2008;68(6):2014–23]
Data from The Roles of Human Sucrose Nonfermenting Protein 2 Homologue in the Tumor-Promoting Functions of Rsf-1
Authors: Sheu Jim Jinn-Chyuan , Choi Jung Hye , Yildiz Isil , Tsai Fuu-Jen , Shaul Yosef , Wang Tian-Li , Shih Ie-Ming
Published: March 2024

Abstract
Rsf-1 interacts with human sucrose nonfermenting protein 2 homologue (hSNF2H) to form a chromatin remodeling complex that participates in several biological processes. We have previously shown that Rsf-1 gene amplification was associated with the most aggressive type of ovarian cancer and cancer cells with Rsf-1 overexpression depended on Rsf-1 to survive. In this report, we determine if formation of the Rsf-1/hSNF2H complex could be one of the mechanisms contributing to tumor cell survival and growth in ovarian carcinomas. Based on immunohistochemistry, we found that Rsf-1 and hSNF2H were co-upregulated in ovarian cancer tissues. Ectopic expression of Rsf-1 in SKOV3 ovarian cancer cells with undetectable endogenous Rsf-1 expression enhanced hSNF2H protein levels and promoted SKOV3 tumor growth in a mouse xenograft model. Our studies also indicated that induction of Rsf-1 expression affected the molecular partnership of hSNF2H and translocated hSNF2H into nuclei where it colocalized with Rsf-1. Furthermore, analysis of Rsf-1 deletion mutants showed that the Rsf-D4 fragment contained the hSNF2H binding site based on coimmunoprecipitation and in vitro competition assays. As compared with other truncated mutants, expression of Rsf-D4 resulted in remarkable growth inhibition in ovarian cancer cells with Rsf-1 gene amplification and overexpression, but not in those without detectable Rsf-1 expression. The above findings suggest that interaction between Rsf-1 and hSNF2H may define a survival signal in those tumors overexpressing Rsf-1. [Cancer Res 2008;68(11):4050–7]
Data from The Polarity Protein Par6 Induces Cell Proliferation and Is Overexpressed in Breast Cancer
Authors: Nolan Marissa E. , Aranda Victoria , Lee Sangjun , Lakshmi Balasubramanian , Basu Srinjan , Allred D. Craig , Muthuswamy Senthil K.
Published: March 2024

Abstract
The polarity protein complex Par6/atypical protein kinase (aPKC)/Cdc42 regulates polarization processes during epithelial morphogenesis, astrocyte migration, and axon specification. We, as well as others, have shown that this complex is also required for disruption of apical-basal polarity during the oncogene ErbB2-induced transformation and transforming growth factor β–induced epithelial-mesenchymal transition of mammary epithelial cells. Here, we report that expression of Par6 by itself in mammary epithelial cells induces epidermal growth factor–independent cell proliferation and development of hyperplastic three-dimensional acini without affecting apical-basal polarity. This is dependent on the ability of Par6 to interact with aPKC and Cdc42, but not Lgl and Par3, and its ability to promote sustained activation of MEK/ERK signaling. Down-regulation of Cdc42 or aPKC expression suppresses the ability of Par6 to induce proliferation, demonstrating that Par6 promotes cell proliferation by interacting with aPKC and Cdc42. We also show that Par6 is overexpressed in breast cancer–derived cell lines and in both precancerous breast lesions and advanced primary human breast cancers, suggesting that Par6 overexpression regulates tumor initiation and progression. Thus, in addition to regulating cell polarization processes, Par6 is an inducer of cell proliferation in breast epithelial cells. [Cancer Res 2008;68(20):8201–9]
Data from Phosphoinositide 3-kinase/AKT Signaling Can Promote AIB1 Stability Independently of GSK3 Phosphorylation
Authors: Ferrero Macarena , Avivar Álvaro , García-Macías María Carmen , de Mora Jaime Font
Published: March 2024

Abstract
The transcriptional coactivator AIB1 is an oncogene overexpressed in different types of tumors, including breast cancer. Although the subcellular compartimentalization of AIB1 seems to be intimately linked to abnormal proliferation, the molecular mechanisms that regulate its subcellular distribution are not well defined. Here, we report that the nuclear accumulation and half-life of AIB1 vary between cancer cell lines. Using these differences as an experimental model, our results reveal that alterations to the Akt signaling pathway and nuclear export determine the stability of AIB1 and nuclear content of this coactivator. Moreover, our results show that AIB1 is degraded in the nucleus by the proteasome in an ubiquitin-dependent manner. However, this process does not require phosphorylation by GSK3, thereby revealing an alternative mechanism for regulating the turnover of AIB1. We define a new region at the carboxy terminus of AIB1 that is required for proteasome-dependent transcriptional activation and is preceded by a PEST domain that is required for adequate protein turnover. Based on differences in Akt signaling and the subcellular distribution of AIB1 between different cell lines, our results suggest that dysregulation of nuclear shuttling and proteasomal degradation may modulate the oncogenic potential of AIB1. [Cancer Res 2008;68(13):5450–9]
Data from Single-Cell Transcription Site Activation Predicts Chemotherapy Response in Human Colorectal Tumors
Authors: Pezo Rossanna C. , Gandhi Saumil J. , Shirley L. Andrew , Pestell Richard G. , Augenlicht Leonard H. , Singer Robert H.
Published: March 2024

Abstract
Candidate gene and pathway approaches, and unbiased gene expression profiling, have identified marker signatures predictive of tumor phenotypes, such as drug sensitivity and invasive or metastatic potential. However, application of such information to evaluation of tumors in the clinic is limited by cell heterogeneity in the tumor. We have developed a novel method of fluorescence in situ hybridization (FISH) that can detect transcriptional activation of individual genes at their site in single cells in the interphase nucleus. A major obstacle in the treatment of colorectal cancer is relative insensitivity to the chemotherapeutic agent 5-Fluorouracil (5-FU). Here, we have developed a sensitive approach to predict relative sensitivity of colorectal cancer cells to 5-FU, using FISH with probes targeted to nascent mRNAs to measure the number of individual cells with active transcription sites for a panel of candidate genes. These results reveal that the transcriptional status of four key genes, thymidylate synthase (TYMS), MORF-related gene X (MRGX), Bcl2-antagonist/killer (BAK), and ATPase, Cu2+ transporting β polypeptide (ATP7B), can accurately predict response to 5-FU. As proof of principle, we show that this transcriptional profile is predictive of response to 5-FU in a small number of patient colon tumor tissues. This approach provides a novel ability to identify and characterize unique minor cell populations in the tumor that may exhibit relative resistance to chemotherapy. [Cancer Res 2008;68(13):4977–82]
Data from Chromosomal Breakpoints in Primary Colon Cancer Cluster at Sites of Structural Variants in the Genome
Authors: Camps Jordi , Grade Marian , Nguyen Quang Tri , Hörmann Patrick , Becker Sandra , Hummon Amanda B. , Rodriguez Virginia , Chandrasekharappa Settara , Chen Yidong , Difilippantonio Michael J. , Becker Heinz , Ghadimi B. Michael , Ried Thomas
Published: March 2024

Abstract
Genomic aberrations on chromosome 8 are common in colon cancer, and are associated with lymph node and distant metastases as well as with disease susceptibility. This prompted us to generate a high-resolution map of genomic imbalances of chromosome 8 in 51 primary colon carcinomas using a custom-designed genomic array consisting of a tiling path of BAC clones. This analysis confirmed the dominant role of this chromosome. Unexpectedly, the position of the breakpoints suggested colocalization with structural variants in the human genome. In order to map these sites with increased resolution and to extend the analysis to the entire genome, we analyzed a subset of these tumors (n = 32) by comparative genomic hybridization on a 185K oligonucleotide array platform. Our comprehensive map of the colon cancer genome confirmed recurrent and specific low-level copy number changes of chromosomes 7, 8, 13, 18, and 20, and unveiled additional, novel sites of genomic imbalances including amplification of a histone gene cluster on chromosome 6p21.1-21.33 and deletions on chromosome 4q34-35. The systematic comparison of segments of copy number change with gene expression profiles showed that genomic imbalances directly affect average expression levels. Strikingly, we observed a significant association of chromosomal breakpoints with structural variants in the human genome: 41% of all copy number changes occurred at sites of such copy number variants (P < 2.2e−16). Such an association has not been previously described and reveals a yet underappreciated plasticity of the colon cancer genome; it also points to potential mechanisms for the induction of chromosomal breakage in cancer cells. [Cancer Res 2008;68(5):1284–95]
Data from Epithelial Progeny of Estrogen-Exposed Breast Progenitor Cells Display a Cancer-like Methylome
Authors: Cheng Alfred S.L. , Culhane Aedín C. , Chan Michael W.Y. , Venkataramu Chinnambally R. , Ehrich Mathias , Nasir Aejaz , Rodriguez Benjamin A.T. , Liu Joseph , Yan Pearlly S. , Quackenbush John , Nephew Kenneth P. , Yeatman Timothy J. , Huang Tim H-M.
Published: March 2024

Abstract
Estrogen imprinting is used to describe a phenomenon in which early developmental exposure to endocrine disruptors increases breast cancer risk later in adult life. We propose that long-lived, self-regenerating stem and progenitor cells are more susceptible to the exposure injury than terminally differentiated epithelial cells in the breast duct. Mammospheres, containing enriched breast progenitors, were used as an exposure system to simulate this imprinting phenomenon in vitro. Using MeDIP-chip, a methylation microarray screening method, we found that 0.5% (120 loci) of human CpG islands were hypermethylated in epithelial cells derived from estrogen-exposed progenitors compared with the non–estrogen-exposed control cells. This epigenetic event may lead to progressive silencing of tumor suppressor genes, including RUNX3, in these epithelial cells, which also occurred in primary breast tumors. Furthermore, normal tissue in close proximity to the tumor site also displayed RUNX3 hypermethylation, suggesting that this aberrant event occurs in early breast carcinogenesis. The high prevalence of estrogen-induced epigenetic changes in primary tumors and the surrounding histologically normal tissues provides the first empirical link between estrogen injury of breast stem/progenitor cells and carcinogenesis. This finding also offers a mechanistic explanation as to why a tumor suppressor gene, such as RUNX3, can be heritably silenced by epigenetic mechanisms in breast cancer. [Cancer Res 2008;68(6):1786–96]
Data from IFN-α and Bortezomib Overcome Bcl-2 and Mcl-1 Overexpression in Melanoma Cells by Stimulating the Extrinsic Pathway of Apoptosis
Authors: Lesinski Gregory B. , Raig Ene T. , Guenterberg Kristan , Brown Lloyd , Go Michael R. , Shah Nisha N. , Lewis Adrian , Quimper Megan , Hade Erinn , Young Gregory , Chaudhury Abhik Ray , Ladner Katherine J. , Guttridge Denis C. , Bouchard Page , Carson William E.
Published: March 2024

Abstract
We hypothesized that IFN-α would enhance the apoptotic activity of bortezomib on melanoma cells. Combined treatment with bortezomib and IFN-α induced synergistic apoptosis in melanoma and other solid tumor cell lines. Apoptosis was associated with processing of procaspase-3, procaspase-7, procaspase-8, and procaspase-9 and with cleavage of Bid and poly(ADP-ribose) polymerase. Bortezomib plus IFN-α was effective at inducing apoptosis in melanoma cells that overexpressed Bcl-2 or Mcl-1, suggesting that this treatment combination can overcome mitochondrial pathways of cell survival and resistance to apoptosis. The proapoptotic effects of this treatment combination were abrogated by a caspase-8 inhibitor, led to increased association of Fas and FADD before the onset of cell death, and were significantly reduced in cells transfected with a dominant-negative FADD construct or small interfering RNA targeting Fas. These data suggest that bortezomib and IFN-α act through the extrinsic pathway of apoptosis via FADD-induced caspase-8 activation to initiate cell death. Finally, bortezomib and IFN-α displayed statistically significant antitumor activity compared with either agent alone in both the B16 murine model of melanoma and in athymic mice bearing human A375 xenografts. These data support the future clinical development of bortezomib and IFN-α for malignant melanoma. [Cancer Res 2008;68(20):8351–60]
Data from Expression of HER2 and Estrogen Receptor α Depends upon Nuclear Localization of Y-Box Binding Protein-1 in Human Breast Cancers
Authors: Fujii Teruhiko , Kawahara Akihiko , Basaki Yuji , Hattori Satoshi , Nakashima Kazutaka , Nakano Kenji , Shirouzu Kazuo , Kohno Kimitoshi , Yanagawa Takashi , Yamana Hideaki , Nishio Kazuto , Ono Mayumi , Kuwano Michihiko , Kage Masayoshi
Published: March 2024

Abstract
In our present study, we examined whether nuclear localization of Y-box binding protein-1 (YB-1) is associated with the expression of epidermal growth factor receptors (EGFR), hormone receptors, and other molecules affecting breast cancer prognosis. The expression of nuclear YB-1, clinicopathologic findings, and molecular markers [EGFR, HER2, estrogen receptor (ER)α, ERβ, progesterone receptor, chemokine (C-X-C motif) receptor 4 (CXCR4), phosphorylated Akt, and major vault protein/lung resistance protein] were immunohistochemically analyzed. The association of the expression of nuclear YB-1 and the molecular markers was examined in breast cancer cell lines using microarrays, quantitative real-time PCR, and Western blot analyses. Knockdown of YB-1 with siRNA significantly reduced EGFR, HER2, and ERα expression in ERα-positive, but not ERα-negative, breast cancer cell lines. Nuclear YB-1 expression was positively correlated with HER2 (P = 0.0153) and negatively correlated with ERα (P = 0.0122) and CXCR4 (P = 0.0166) in human breast cancer clinical specimens but was not correlated with EGFR expression. Nuclear YB-1 expression was an independent prognostic factor for overall (P = 0.0139) and progression-free (P = 0.0280) survival. In conclusion, nuclear YB-1 expression might be essential for the acquisition of malignant characteristics via HER2-Akt–dependent pathways in breast cancer patients. The nuclear localization of YB-1 could be an important therapeutic target against not only multidrug resistance but also tumor growth dependent on HER2 and ERα. [Cancer Res 2008;68(5):1504–12]
Data from ADAM15 Supports Prostate Cancer Metastasis by Modulating Tumor Cell–Endothelial Cell Interaction
Authors: Najy Abdo J. , Day Kathleen C. , Day Mark L.
Published: March 2024

Abstract
Using human tumor and cDNA microarray technology, we have recently shown that the ADAM15 disintegrin is significantly overexpressed during the metastatic progression of human prostate cancer. In the current study, we used lentiviral-based short hairpin RNA (shRNA) technology to down-regulate ADAM15 in the metastatic prostate cancer cell line, PC-3. ADAM15 down-regulation dramatically attenuated many of the malignant characteristics of PC-3 cells in vitro and prevented the s.c. growth of PC-3 cells in severe combined immunodeficient (SCID) mice. By inhibiting the expression of ADAM15 in PC-3 cells, we showed decreased cell migration and adhesion to specific extracellular matrix proteins. This was accompanied by a reduction in the cleavage of N-cadherin by ADAM15 at the cell surface. Fluorescence-activated cell sorting analysis revealed reduced cell surface expression of the metastasis-associated proteins αv integrin and CD44. Furthermore, matrix metalloproteinase 9 secretion and activity were abrogated in response to ADAM15 reduction. In an in vitro model of vascular invasion, loss of ADAM15 reduced PC-3 adhesion to, and migration through, vascular endothelial cell monolayers. Using an SCID mouse model of human prostate cancer metastasis, we found that the loss of ADAM15 significantly attenuated the metastatic spread of PC-3 cells to bone. Taken together, these data strongly support a functional role for ADAM15 in prostate tumor cell interaction with vascular endothelium and the metastatic progression of human prostate cancer. [Cancer Res 2008;68(4):1092–9]
Data from Glycogen Synthase Kinase 3β Regulates Cell Death Induced by Synthetic Triterpenoids
Authors: Venè Roberta , Larghero Patrizia , Arena Giuseppe , Sporn Michael B. , Albini Adriana , Tosetti Francesca
Published: March 2024

Abstract
The induction of programmed cell death in premalignant or malignant cancer cells by chemopreventive agents could be a valuable tool to control prostate cancer initiation and progression. In this work, we present evidence that the C-28 methyl ester of the synthetic oleanane triterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (CDDO-Me) induces cell death in androgen-responsive and unresponsive human prostate cancer cell lines at nanomolar and low micromolar concentrations. CDDO-Me induced caspase-3, caspase-8, and caspase-9 activation; poly(ADP-ribose) polymerase cleavage; internucleosomal DNA fragmentation; and loss of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction in PC3 and DU145 cells. However, caspase-3 and caspase-8 inhibition by Z-DEVD-fmk and Z-IETD-fmk, respectively, or general caspase inhibition by BOC-D-fmk or Z-VAD-fmk did not rescue loss of cell viability induced by CDDO-Me, suggesting the activation of additional caspase-independent mechanisms. Interestingly, CDDO-Me induced inactivating phosphorylation at Ser9 of glycogen synthase kinase 3β (GSK3β), a multifunctional kinase that mediates essential events promoting prostate cancer development and acquisition of androgen independence. The GSK3 inhibitor lithium chloride and, more effectively, GSK3 gene silencing sensitized PC3 and DU145 prostate cancer cells to CDDO-Me cytotoxicity. These data suggest that modulation of GSK3β activation is involved in the cell death pathway engaged by CDDO-Me in prostate cancer cells. [Cancer Res 2008;68(17):6987–96]
Data from Kaiso Contributes to DNA Methylation-Dependent Silencing of Tumor Suppressor Genes in Colon Cancer Cell Lines
Authors: Lopes Eloisi C. , Valls Ester , Figueroa Maria E. , Mazur Alexander , Meng Fan-Guo , Chiosis Gabriela , Laird Peter W. , Schreiber-Agus Nicole , Greally John M. , Prokhortchouk Egor , Melnick Ari
Published: March 2024

Abstract
Aberrant CpG methylation of tumor suppressor gene regulatory elements is associated with transcriptional silencing and contributes to malignant transformation of different tissues. It is presumed that methylated DNA sequences recruit repressor machinery to actively shutdown gene expression. The Kaiso protein is a transcriptional repressor expressed in human and murine colorectal tumors that can bind to methylated clusters of CpG dinucleotides. We show here that Kaiso represses methylated tumor suppressor genes and can bind in a methylation-dependent manner to the CDKN2A in human colon cancer cell lines. The contribution of Kaiso to epigenetic silencing was underlined by the fact that Kaiso depletion induced tumor suppressor gene expression without affecting DNA methylation levels. As a consequence, colon cancer cells became susceptible to cell cycle arrest and cell death mediated by chemotherapy. The data suggest that Kaiso is a methylation-dependent “opportunistic” oncogene that silences tumor suppressor genes when they become hypermethylated. Because Kaiso inactivation sensitized colon cancer cell lines to chemotherapy, it is possible that therapeutic targeting of Kaiso could improve the efficacy of current treatment regimens. [Cancer Res 2008;68(18):7258–63]
Data from Rat Prolactinoma Cell Growth Regulation by Epidermal Growth Factor Receptor Ligands
Authors: Vlotides George , Siegel Emily , Donangelo Ines , Gutman Shiri , Ren Song-Guang , Melmed Shlomo
Published: March 2024

Abstract
Epidermal growth factor (EGF) regulates pituitary development, hormone synthesis, and cell proliferation. Although ErbB receptor family members are expressed in pituitary tumors, the effects of EGF signaling on pituitary tumors are not known. Immunoprecipitation and Western blot confirmed EGF receptor (EGFR) and p185c-neu protein expression in GH3 lacto-somatotroph but not in adrenocorticotropic hormone–secreting AtT20 pituitary tumor cells. EGF (5 nmol/L) selectively enhanced baseline (∼4-fold) and serum-induced (>6-fold) prolactin (PRL) mRNA levels, whereas gefitinib, an EGFR antagonist, suppressed serum-induced cell proliferation and Pttg1 expression, blocked PRL gene expression, and reversed EGF-mediated somatotroph-lactotroph phenotype switching. Downstream EGFR signaling by ERK, but not phosphoinositide-3-kinase or protein kinase C, mediated the gefitinib response. Tumors in athymic mice implanted s.c. with GH3 cells resulted in weight gain accompanied by increased serum PRL, growth hormone, and insulin growth factor 1. Gefitinib decreased tumor volumes and peripheral hormone levels by ∼30% and restored normal mouse body weight patterns. Mice treated with gefitinib exhibited decreased tumor tissue ERK1/2 phosphorylation and down-regulated tumor PRL and Pttg1 mRNA abundance. These results show that EGFR inhibition controls tumor growth and PRL secretion in experimental lacto-somatotroph tumors. EGFR inhibitors could therefore be useful for the control of PRL secretion and tumor load in prolactinomas resistant to dopaminergic treatment, or for those prolactinomas undergoing rare malignant transformation. [Cancer Res 2008;68(15):6377–86]
Data from Deletion of Yin Yang 1 Protein in Osteosarcoma Cells on Cell Invasion and CXCR4/Angiogenesis and Metastasis
Authors: de Nigris Filomena , Rossiello Raffaele , Schiano Concetta , Arra Claudio , Williams-Ignarro Sharon , Barbieri Antonio , Lanza Alessandro , Balestrieri Antonio , Giuliano Maria Teresa , Ignarro Louis J. , Napoli Claudio
Published: March 2024

Abstract
We know that the Yin Yang 1 protein (YY1) overexpression is positively and strongly correlated with the degree of malignancy of bone tumors. Therefore, we questioned whether we could influence cell invasiveness by deleting YY1 in human osteosarcoma cells (SaOs-2), as tested in Matrigel-coated filters and metastasis implantation of such osteosarcoma cells in vivo, by serial analysis with nuclear magnetic resonance. Moreover, we focused our work on the chemokine receptor CXCR4 and its inhibition by T22 antibody, as well as on systemic (direct in vivo assay) and computer-assisted imaging of angiogenesis-related metastasis. Results showed that cell invasiveness and metastasis implantation by wild-type SaOs-2 cells, as evaluated by histology and immunohistochemistry, are associated with up-regulation of CXCR4 expression, which in turn was significantly reduced by T22. In addition, deletion of YY1 (siRNAYY1-SaOs-2) induced a significant decrease of cell invasion and metastasis growth. This phenomenon was associated with decreased vascular endothelial growth factor (VEGF)/angiogenesis and a complex rearrangement of the gene expression profile as evaluated by microarray analysis. In conclusion, YY1 and VEGF/CXCR4 seem to intervene in the pathogenesis of the malignant phenotype of osteosarcoma by acting on cell invasiveness and metastasis growth. [Cancer Res 2008;68(6):1797–808]
Data from Mitochondrial Cytochrome B Gene Mutation Promotes Tumor Growth in Bladder Cancer
Authors: Dasgupta Santanu , Hoque Mohammad Obaidul , Upadhyay Sunil , Sidransky David
Published: March 2024

Abstract
Mitochondria-encoded Cytochrome B (CYTB) gene mutations were reported in different cancers, but the effect of these mutations on cellular metabolism and growth is unknown. In a murine xenograft and human model of bladder cancer, we show the functional effect of overexpression of a 21-bp deletion mutation (mt) of CYTB. Overexpression of mtCYTB generated increased reactive oxygen species (ROS) accompanied by increased oxygen consumption and lactate production. MtCYTB overexpression induced significant tumor growth in vitro and in vivo by triggering rapid cell cycle progression through up-regulation of the nuclear factor-κB2 signaling pathway. Tumor-generated ROS induced in vitro lysis of normal splenocytes. Thus, we present physiologic and functional evidence for the role of a bonafide mitochondrial gene mutation in cancer. [Cancer Res 2008;68(3):700–06]
Data from Identification of Novel Isoforms of the EML4-ALK Transforming Gene in Non–Small Cell Lung Cancer
Authors: Choi Young Lim , Takeuchi Kengo , Soda Manabu , Inamura Kentaro , Togashi Yuki , Hatano Satoko , Enomoto Munehiro , Hamada Toru , Haruta Hidenori , Watanabe Hideki , Kurashina Kentaro , Hatanaka Hisashi , Ueno Toshihide , Takada Shuji , Yamashita Yoshihiro , Sugiyama Yukihiko , Ishikawa Yuichi , Mano Hiroyuki
Published: March 2024

Abstract
The genome of a subset of non–small-cell lung cancers (NSCLC) harbors a small inversion within chromosome 2 that gives rise to a transforming fusion gene, EML4-ALK, which encodes an activated protein tyrosine kinase. Although breakpoints within EML4 have been identified in introns 13 and 20, giving rise to variants 1 and 2, respectively, of EML4-ALK, it has remained unclear whether other isoforms of the fusion gene are present in NSCLC cells. We have now screened NSCLC specimens for other in-frame fusion cDNAs that contain both EML4 and ALK sequences. Two slightly different fusion cDNAs in which exon 6 of EML4 was joined to exon 20 of ALK were each identified in two individuals of the cohort. Whereas one cDNA contained only exons 1 to 6 of EML4 (variant 3a), the other also contained an additional 33-bp sequence derived from intron 6 of EML4 (variant 3b). The protein encoded by the latter cDNA thus contained an insertion of 11 amino acids between the EML4 and ALK sequences of that encoded by the former. Both variants 3a and 3b of EML4-ALK exhibited marked transforming activity in vitro as well as oncogenic activity in vivo. A lung cancer cell line expressing endogenous variant 3 of EML4-ALK underwent cell death on exposure to a specific inhibitor of ALK catalytic activity. These data increase the frequency of EML4-ALK–positive NSCLC tumors and bolster the clinical relevance of this oncogenic kinase. [Cancer Res 2008;68(13):4971–6]
Data from Dual-Specificity Phosphatase 1 Ubiquitination in Extracellular Signal-Regulated Kinase–Mediated Control of Growth in Human Hepatocellular Carcinoma
Authors: Calvisi Diego F. , Pinna Federico , Meloni Floriana , Ladu Sara , Pellegrino Rossella , Sini Marcella , Daino Lucia , Simile Maria M. , De Miglio Maria R. , Virdis Patrizia , Frau Maddalena , Tomasi Maria L. , Seddaiu Maria A. , Muroni Maria R. , Feo Francesco , Pascale Rosa M.
Published: March 2024

Abstract
Sustained activation of extracellular signal-regulated kinase (ERK) has been detected previously in numerous tumors in the absence of RAS-activating mutations. However, the molecular mechanisms responsible for ERK-unrestrained activity independent of RAS mutations remain unknown. Here, we evaluated the effects of the functional interactions of ERK proteins with dual-specificity phosphatase 1 (DUSP1), a specific inhibitor of ERK, and S-phase kinase-associated protein 2 (SKP2)/CDC28 protein kinase 1b (CKS1) ubiquitin ligase complex in human hepatocellular carcinoma (HCC). Levels of DUSP1, as assessed by real-time reverse transcription–PCR and Western blot analysis, were significantly higher in tumors with better prognosis (as defined by the length of patients' survival) when compared with both normal and nontumorous surrounding livers, whereas DUSP1 protein expression sharply declined in all HCC with poorer prognosis. In the latter HCC subtype, DUSP1 inactivation was due to either ERK/SKP2/CKS1-dependent ubiquitination or promoter hypermethylation associated with loss of heterozygosity at the DUSP1 locus. Noticeably, expression levels of DUSP1 inversely correlated with those of activated ERK, as well as with proliferation index and microvessel density, and directly with apoptosis and survival rate. Subsequent functional studies revealed that DUSP1 reactivation led to suppression of ERK, CKS1, and SKP2 activity, inhibition of proliferation and induction of apoptosis in human hepatoma cell lines. Taken together, the present data indicate that ERK achieves unrestrained activity during HCC progression by triggering ubiquitin-mediated proteolysis of its specific inhibitor DUSP1. Thus, DUSP1 may represent a valuable prognostic marker and ERK, CKS1, or SKP2 potential therapeutic targets for human HCC. [Cancer Res 2008;68(11):4192–200]
Data from Coordinated Epidermal Growth Factor Receptor Pathway Gene Overexpression Predicts Epidermal Growth Factor Receptor Inhibitor Sensitivity in Pancreatic Cancer
Authors: Jimeno Antonio , Tan Aik Choon , Coffa Jordy , Rajeshkumar N.V. , Kulesza Peter , Rubio-Viqueira Belen , Wheelhouse Jenna , Diosdado Begoña , Messersmith Wells A. , Iacobuzio-Donahue Christine , Maitra Anirban , Varella-Garcia Marileila , Hirsch Fred R. , Meijer Gerrit A. , Hidalgo Manuel
Published: March 2024

Abstract
The epidermal growth factor receptor (EGFR) inhibitor erlotinib is approved for treatment of pancreatic cancer but the overall activity is minimal, and known predictive factors for EGFR inhibitor efficacy are infrequent in this disease. We tested the hypothesis that global activation of the EGFR pathway is predictive of EGFR inhibitor efficacy. Pancreatic cancer tumors directly xenografted at surgery were treated with the EGFR inhibitors erlotinib and cetuximab and analyzed for biological features. Two of 10 tumors were sensitive, and by global gene expression profiling with gene set enrichment analysis, the EGFR pathway was highly expressed in sensitive compared with resistant tumors. The core gene components driving EGFR pathway overexpression were pathway ligands and positive effectors. In a prospective validation, the EGFR pathway-based signature correctly predicted anti-EGFR treatment response in eight additional tumors and was not predictive of response to gemcitabine and CI1040 (a MEK inhibitor). Analysis of EGFR, KRAS, and PIK3CA mutations and gene amplification by fluorescence in situ hybridization and multiplex ligation-dependent probe amplification showed that none of these genetic abnormalities were neither predictive nor responsible for the EGFR pathway activation. Coordinated overexpression of the EGFR pathway predicts susceptibility to EGFR inhibitors in pancreatic cancer. These results suggest a phenomenon of pathway addiction and support the value of unbiased system biology approaches in drug development. [Cancer Res 2008;68(8):2841–9]
Data from DNA Hypomethylation Arises Later in Prostate Cancer Progression than CpG Island Hypermethylation and Contributes to Metastatic Tumor Heterogeneity
Authors: Yegnasubramanian Srinivasan , Haffner Michael C. , Zhang Yonggang , Gurel Bora , Cornish Toby C. , Wu Zhijin , Irizarry Rafael A. , Morgan James , Hicks Jessica , DeWeese Theodore L. , Isaacs William B. , Bova G. Steven , De Marzo Angelo M. , Nelson William G.
Published: March 2024

Abstract
Hypomethylation of CpG dinucleotides in genomic DNA was one of the first somatic epigenetic alterations discovered in human cancers. DNA hypomethylation is postulated to occur very early in almost all human cancers, perhaps facilitating genetic instability and cancer initiation and progression. We therefore examined the nature, extent, and timing of DNA hypomethylation changes in human prostate cancer. Contrary to the prevailing view that global DNA hypomethylation changes occur extremely early in all human cancers, we show that reductions in 5meC content in the genome occur very late in prostate cancer progression, appearing at a significant extent only at the stage of metastatic disease. Furthermore, we found that, whereas some LINE1 promoter hypomethylation does occur in primary prostate cancers compared with normal tissues, this LINE1 hypomethylation is significantly more pronounced in metastatic prostate cancer. Next, we carried out a tiered gene expression microarray and bisulfite genomic sequencing–based approach to identify genes that are silenced by CpG island methylation in normal prostate cells but become overexpressed in prostate cancer cells as a result of CpG island hypomethylation. Through this analysis, we show that a class of cancer testis antigen genes undergoes CpG island hypomethylation and overexpression in primary prostate cancers, but more so in metastatic prostate cancers. Finally, we show that DNA hypomethylation patterns are quite heterogeneous across different metastatic sites within the same patients. These findings provide evidence that DNA hypomethylation changes occur later in prostate carcinogenesis than the CpG island hypermethylation changes and occur heterogeneously during prostate cancer progression and metastatic dissemination. [Cancer Res 2008;68(21):8954–67]
Data from Lysyl Oxidase–Like 2 as a New Poor Prognosis Marker of Squamous Cell Carcinomas
Authors: Peinado Héctor , Moreno-Bueno Gema , Hardisson David , Pérez-Gómez Eduardo , Santos Vanesa , Mendiola Marta , de Diego Juan Ignacio , Nistal Manuel , Quintanilla Miguel , Portillo Francisco , Cano Amparo
Published: March 2024

Abstract
Lysyl oxidase–like 2 (Loxl2) interacts with and stabilizes Snai1 transcription factor, promoting epithelial-mesenchymal transition. Either Loxl2 or Snai1 knock-down blocks tumor growth and induces differentiation, but the specific role of each factor in tumor progression is still unknown. Comparison of the gene expression profiles of the squamous cell carcinoma cell line HaCa4 after knocking-down Loxl2 or Snai1 revealed that a subset of epidermal differentiation genes was specifically up-regulated in Loxl2-silenced cells. In agreement, although both Loxl2- and Snai1-knockdown cells showed reduced in vivo invasion, only Loxl2-silenced cells exhibited a skin-like epidermal differentiation program. In addition, we show that expression of Loxl2 and Snai1 correlates with malignant progression in a two-stage mouse skin carcinogenesis model. Furthermore, we found that increased expression of both LOXL2 and SNAI1 correlates with local recurrence in a cohort of 256 human laryngeal squamous cell carcinomas. We describe for the first time that high levels of LOXL2 are associated with decreased overall and disease-free survival in laryngeal squamous cell carcinomas, lung squamous cell carcinoma, and lymph node–negative (N0) breast adenocarcinomas. Altogether, our results show that LOXL2 can be used as a new poor prognosis indicator in human squamous cell carcinomas promoting malignant transformation by both SNAI1-dependent and SNAI1-independent pathways. [Cancer Res 2008;68(12):4541–50]
Data from Dissecting and Targeting the Growth Factor–Dependent and Growth Factor–Independent Extracellular Signal-Regulated Kinase Pathway in Human Schwannoma
Authors: Ammoun Sylwia , Flaiz Christine , Ristic Natalia , Schuldt Jennifer , Hanemann C. Oliver
Published: March 2024

Abstract
Schwannomas are tumors of the nervous system that occur sporadically and in patients with the cancer predisposition syndrome neurofibromatosis type 2 (NF2). Schwannomas and all NF2-related tumors are caused by loss of the tumor suppressor merlin. Using our human in vitro model for schwannoma, we analyzed extracellular signal-regulated kinase 1/2 (ERK1/2) and AKT signaling pathways, their upstream growth factor receptors, and their role in schwannoma cell proliferation and adhesion to find new systemic therapies for these tumors that, to date, are very difficult to treat. We show here that human primary schwannoma cells show an enhanced basal Raf/mitogen-activated protein/ERK kinase/ERK1/2 pathway activity compared with healthy Schwann cells. Due to a strong and prolonged activation of platelet-derived growth factor receptor β (PDGFRβ), which is highly overexpressed, ERK1/2 and AKT activation was further increased in schwannoma, leading to increased proliferation. Using specific inhibitors, we discovered that ERK1/2 activation involves the integrin/focal adhesion kinase/Src/Ras signaling cascades and PDGFRβ-mediated ERK1/2 activation is triggered through the phosphatidylinositol 3-kinase/protein kinase C/Src/c-Raf pathway. Due to the complexity of signals leading to schwannoma cell proliferation, potential new therapeutic agents should target several signaling pathways. The PDGFR and c-Raf inhibitor sorafenib (BAY 43-9006; Bayer Pharmaceuticals), currently approved for treatment of advanced renal cell cancer, inhibits both basal and PDGFRβ-mediated ERK1/2 and AKT activity and decreases cell proliferation in human schwannoma cells, suggesting that this drug constitutes a promising tool to treat schwannomas. We conclude that our schwannoma in vitro model can be used to screen for new therapeutic targets in general and that sorafenib is possible candidate for future clinical trials. [Cancer Res 2008;68(13):5236–45]
Data from Mechanisms of Antileukemic Activity of the Novel Bcl-2 Homology Domain-3 Mimetic GX15-070 (Obatoclax)
Authors: Konopleva Marina , Watt Julie , Contractor Rooha , Tsao Twee , Harris David , Estrov Zeev , Bornmann William , Kantarjian Hagop , Viallet Jean , Samudio Ismael , Andreeff Michael
Published: March 2024

Abstract
In this study, we investigated the mechanism of apoptosis induction of obatoclax (GX15-070), a novel Bcl-2 homology domain-3 (BH3) mimetic, in acute myeloid leukemia (AML) cell lines and primary AML samples. Obatoclax inhibited cell growth of HL-60, U937, OCI-AML3, and KG-1 cell lines. Apoptosis induction contributed to the observed antiproliferative effects at concentrations of this agent that mirror its affinity for antiapoptotic Bcl-2 proteins. We show that obatoclax can promote the release of cytochrome c from isolated leukemia cell mitochondria and that apoptosis induced by this agent is preceded by the release of Bak from Mcl-1, liberation of Bim from both Bcl-2 and Mcl-1, and the formation of an active Bak/Bax complex. Notably, apoptosis was diminished, but not fully prevented, in the absence of Bak/Bax or Bim, suggesting that obatoclax has additional targets that contribute to its cytotoxicity. At growth inhibitory doses that did not induce apoptosis or decrease viability, obatoclax induced an S-G2 cell-cycle block. Obatoclax induced apoptosis in AML CD34+ progenitor cells with an average IC50 of 3.59 ± 1.23 μmol/L although clonogenicity was inhibited at concentrations of 75 to 100 nmol/L. Obatoclax synergized with the novel BH3 mimetic ABT-737 to induce apoptosis in OCI-AML3 cells and synergistically induced apoptosis in combination with AraC in leukemic cell lines and in primary AML samples. In conclusion, we show that obatoclax potently induces apoptosis and decreases leukemia cell proliferation and may be used in a novel therapeutic strategy for AML alone and in combination with other targeted agents and chemotherapeutics. [Cancer Res 2008;68(9):3413–20]
Data from Src and ADAM-17–Mediated Shedding of Transforming Growth Factor-α Is a Mechanism of Acute Resistance to TRAIL
Authors: Van Schaeybroeck Sandra , Kelly Donal M. , Kyula Joan , Stokesberry Susan , Fennell Dean A. , Johnston Patrick G. , Longley Daniel B.
Published: March 2024

Abstract
Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL/Apo-2L) has emerged as a promising anticancer agent. However, resistance to TRAIL is likely to be a major problem, and sensitization of cancer cells to TRAIL may therefore be an important anticancer strategy. In this study, we examined the effect of the epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI) gefitinib and a human epidermal receptor 2 (HER2)–TKI (M578440) on the sensitivity of human colorectal cancer (CRC) cell lines to recombinant human TRAIL (rhTRAIL). A synergistic interaction between rhTRAIL and gefitinib and rhTRAIL and M578440 was observed in both rhTRAIL-sensitive and resistant CRC cells. This synergy correlated with an increase in EGFR and HER2 activation after rhTRAIL treatment. Furthermore, treatment of CRC cells with rhTRAIL resulted in activation of the Src family kinases (SFK). Importantly, we found that rhTRAIL treatment induced shedding of transforming growth factor-α (TGF-α) that was dependent on SFK activity and the protease ADAM-17. Moreover, this shedding of TGF-α was critical for rhTRAIL-induced activation of EGFR. In support of this, SFK inhibitors and small interfering RNAs targeting ADAM-17 and TGF-α also sensitized CRC cells to rhTRAIL-mediated apoptosis. Taken together, our findings indicate that both rhTRAIL-sensitive and resistant CRC cells respond to rhTRAIL treatment by activating an EGFR/HER2-mediated survival response and that these cells can be sensitized to rhTRAIL using EGFR/HER2-targeted therapies. Furthermore, this acute response to rhTRAIL is regulated by SFK-mediated and ADAM-17–mediated shedding of TGF-α, such that targeting SFKs or inhibiting ADAM-17, in combination with rhTRAIL, may enhance the response of CRC tumors to rhTRAIL. [Cancer Res 2008;68(20):8312–21]
Data from Glucagon-like Peptide-2 Does Not Modify the Growth or Survival of Murine or Human Intestinal Tumor Cells
Authors: Koehler Jacqueline A. , Harper Will , Barnard Maja , Yusta Bernardo , Drucker Daniel J.
Published: March 2024

Abstract
Glucagon-like peptide-2 (GLP-2) secreted from enteroendocrine cells exerts proabsorptive, regenerative, and cytoprotective actions in the normal and injured gut epithelium. Hence, sustained GLP-2 receptor (GLP-2R) activation represents a strategy under investigation for the prevention and treatment of chemotherapy-induced mucositis. Nevertheless, the consequences of increased GLP-2R signaling for the growth and survival of intestinal tumor cells remain poorly understood. We studied the proliferative and cytoprotective actions of GLP-2 in human colon cancer cells stably transfected with the GLP-2R and in nude mice harboring GLP-2R+ human colon cancer cells. The importance of the GLP-2R for tumor growth was also examined in ApcMin/+ mice chronically treated with exogenous GLP-2 and in ApcMin/+:Glp2r−/− mice. GLP-2 increased cyclic AMP accumulation and produced cell-specific activation of growth and survival pathways in DLD-1, SW480, and HT29 cells. However, GLP-2 did not stimulate cell growth or attenuate cycloheximide-, LY294002-, indomethacin-, or chemotherapy-induced cytotoxicity in vitro. Moreover, chronic GLP-2 administration had no effect on the growth of human colon cancer cell xenografts in nude mice in vivo. Daily GLP-2 treatment for 7 weeks increased growth of normal gut mucosa but did not increase the number or size of polyps in ApcMin/+ mice, and genetic disruption of the Glp2r gene in ApcMin/+ mice did not modify polyp size or number. Taken together, although GLP-2R activation engages signaling pathways promoting cell proliferation and cytoprotection in the normal gut epithelium, sustained direct or indirect modulation of GLP-2R signaling does not modify intestinal tumor cell growth or survival. [Cancer Res 2008;68(19):7897–904]