bluuebunny/crossref_metadata_2025 huggingface dataset:
Data from Malignant Progression and Blockade of Angiogenesis in a Murine Transgenic Model of Neuroblastoma
Authors: Chesler Louis , Goldenberg David D. , Seales Isha T. , Satchi-Fainaro Ronit , Grimmer Matt , Collins Rodney , Struett Chris , Nguyen Kim N. , Kim Grace , Tihan Tarik , Bao Yun , Brekken Rolf A. , Bergers Gabriele , Folkman Judah , Weiss William A.
Published: March 2023

Abstract
Targeted expression of MYCN to the neural crest [under control of the rat tyrosine hydroxylase (TH) promoter] causes neuroblastoma in transgenic mice (TH-MYCN) and is a well-established model for this disease. Because high levels of MYCN are associated with enhanced tumor angiogenesis and poor clinical outcome in neuroblastoma, we serially characterized malignant progression, angiogenesis, and sensitivity to angiogenic blockade in tumors from these animals. Tumor cells were proliferative, secreted high levels of the angiogenic ligand vascular endothelial growth factor (VEGF), and recruited a complex vasculature expressing the angiogenic markers VEGF-R2, α-SMA, and matrix metalloproteinases MMP-2 and MMP-9, all of which are also expressed in human disease. Treatment of established murine tumors with the angiogenesis inhibitor TNP-470 caused near-complete ablation, with reduced proliferation, enhanced apoptosis, and vasculature disruption. Because TNP-470 has been associated with neurotoxicity, we tested the recently described water-soluble HPMA copolymer–TNP-470 conjugate (caplostatin), which showed comparable efficacy and was well tolerated without weight loss or neurotoxicity as measured by rotarod testing. This study highlights the importance of angiogenesis inhibition in a spontaneous murine tumor with native tumor–microenvironment interactions, validates the use of mice transgenic for TH-MYCN as a model for therapy in this common pediatric tumor, and supports further clinical development of caplostatin as an antiangiogenic therapy in childhood neuroblastoma. [Cancer Res 2007;67(19):9435–42]
Data from Reduced PDEF Expression Increases Invasion and Expression of Mesenchymal Genes in Prostate Cancer Cells
Authors: Gu Xuesong , Zerbini Luiz F. , Otu Hasan H. , Bhasin Manoj , Yang Quanli , Joseph Marie G. , Grall Franck , Onatunde Tomi , Correa Ricardo G. , Libermann Towia A.
Published: March 2023

Abstract
The epithelium-specific Ets transcription factor, PDEF, plays a role in prostate and breast cancer, although its precise function has not been established. In prostate cancer, PDEF is involved in regulating prostate-specific antigen expression via interaction with the androgen receptor and NKX3.1, and down-regulation of PDEF by antiproliferative agents has been associated with reduced PDEF expression. We now report that reduced expression of PDEF leads to a morphologic change, increased migration and invasiveness in prostate cancer cells, reminiscent of transforming growth factor β (TGFβ) function and epithelial-to-mesenchymal transition. Indeed, inhibition of PDEF expression triggers a transcriptional program of genes involved in the TGFβ pathway, migration, invasion, adhesion, and epithelial dedifferentiation. Our results establish PDEF as a critical regulator of genes involved in cell motility, invasion, and adhesion of prostate cancer cells. [Cancer Res 2007;67(9):4219–26]
Data from RNA Interference Inhibition of Matrix Metalloproteinase-1 Prevents Melanoma Metastasis by Reducing Tumor Collagenase Activity and Angiogenesis
Authors: Blackburn Jessica S. , Rhodes C. Harker , Coon Charles I. , Brinckerhoff Constance E.
Published: March 2023

Abstract
Melanoma incidence is increasing worldwide, and metastatic melanoma is almost completely resistant to every known therapy. New approaches to treating melanoma are urgently needed, and a greater understanding of the biology of melanoma invasion and metastasis will aid in their creation. A high proportion of invasive melanomas have a constitutively active Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK/ERK) signaling cascade; however, the downstream effectors of ERK signaling that contribute to melanoma invasion and metastasis are unknown. ERK signaling drives the production of the interstitial collagenase matrix metalloproteinase-1 (MMP-1), which is expressed specifically by invasive melanomas. Using short hairpin RNAs (shRNA) to knock down MMP-1 expression in a human melanoma cell line, we investigated the role of MMP-1 in melanoma metastasis in a xenograft model. Knockdown of MMP-1 had no effect on primary tumor growth, but reduction of MMP-1 expression significantly decreased the ability of the melanoma to metastasize from the orthotopic site in the dermis to the lung. Mechanistically, tumor cells expressing MMP-1 shRNAs had diminished collagenase activity, which is required for tumor cell invasion. Additionally, attenuation of MMP-1 expression reduced angiogenesis. These results show, for the first time, that targeted inhibition of MMP-1, a single effector of the Raf/MEK/ERK signaling cascade, prevents the progression of melanoma from a primary to metastatic tumor and, as such, may represent a useful therapeutic tool in controlling this disease. [Cancer Res 2007;67(22):10849–58]
Data from Hsp27 Modulates p53 Signaling and Suppresses Cellular Senescence
Authors: O'Callaghan-Sunol Cornelia , Gabai Vladimir L. , Sherman Michael Y.
Published: March 2023

Abstract
The small heat shock protein Hsp27 is expressed at high levels in many tumors and provides protection against anticancer drugs. Here, we show that expression of recombinant Hsp27 at elevated levels leads to protection of MCF10A human mammary epithelial cells from doxorubicin. The protection was associated with suppression of the doxorubicin-induced senescence, where Hsp27 inhibited p53-mediated induction of p21, the major regulator of the senescence program. Similarly, Hsp27 inhibited accumulation of p21 and suppressed senescence in response to the p53 activator nutlin-3, indicating that Hsp27 has a general effect on the p53 pathway. In line with these findings, down-regulation of Hsp27 in HCT116 human colon carcinoma cells that express this heat shock protein at high levels caused senescence in a population of cells and sensitized the rest of the cells to doxorubicin-induced senescence (at low doses) or apoptosis (at high doses of doxorubicin). Induction of senescence by Hsp27 down-regulation associated with activation of the p53 pathway and induction of p21. Interestingly, depletion of Hsp27 caused neither significant proteotoxic nor genotoxic stress, and therefore this heat shock protein seems to have a specific effect on the p53 signaling. Indeed, Hsp27 down-regulation was associated with destabilization of HDM2 and stabilization of p53. These data suggest that Hsp27 may play a general role in regulation of cellular senescence by modulating the p53 pathway. [Cancer Res 2007;67(24):11779–88]
Data from Reduced Colitis-Associated Colon Cancer in Fat-1 (n-3 Fatty Acid Desaturase) Transgenic Mice
Authors: Jia Qian , Lupton Joanne R. , Smith Roger , Weeks Brad R. , Callaway Evelyn , Davidson Laurie A. , Kim Wooki , Fan Yang-Yi , Yang Peiying , Newman Robert A. , Kang Jing X. , McMurray David N. , Chapkin Robert S.
Published: March 2023

Abstract
Bioactive food components containing n-3 polyunsaturated fatty acids (PUFA) modulate multiple determinants that link inflammation to cancer initiation and progression. Therefore, in this study, fat-1 transgenic mice, which convert endogenous n-6 PUFA to n-3 PUFA in multiple tissues, were injected with azoxymethane followed by three cycles of dextran sodium sulfate (DSS) to induce colitis-associated cancer. Fat-1 mice exhibited a reduced number of colonic adenocarcinomas per mouse (1.05 ± 0.29 versus 2.12 ± 0.51, P = 0.033), elevated apoptosis (P = 0.03), and a decrease in n-6 PUFA–derived eicosanoids, compared with wild-type (wt) mice. To determine whether the chemoprotective effects of n-3 PUFA could be attributed to its pleiotropic anti-inflammatory properties, colonic inflammation and injury scores were evaluated 5 days after DSS exposure followed by either a 3-day or 2-week recovery period. There was no effect of n-3 PUFA at 3 days. However, following a 2-week recovery period, colonic inflammation and ulceration scores returned to pretreatment levels compared with 3-day recovery only in fat-1 mice. For the purpose of examining the specific reactivity of lymphoid elements in the intestine, CD3+ T cells, CD4+ T helper cells, and macrophages from colonic lamina propria were quantified. Comparison of 3-day versus 2-week recovery time points revealed that fat-1 mice exhibited decreased (P < 0.05) CD3+, CD4+ T helper, and macrophage cell numbers per colon as compared with wt mice. These results suggest that the antitumorigenic effect of n-3 PUFA may be mediated, in part, via its anti-inflammatory properties. [Cancer Res 2008;68(10):3985–91]
Data from Six1 Overexpression in Ovarian Carcinoma Causes Resistance to TRAIL-Mediated Apoptosis and Is Associated with Poor Survival
Authors: Behbakht Kian , Qamar Lubna , Aldridge Carrie S. , Coletta Ricardo D. , Davidson Susan A. , Thorburn Andrew , Ford Heide L.
Published: March 2023

Abstract
Tumorigenesis can arise from inappropriate activation of developmental genes in mature tissues. Here, we show that the developmental regulator Six1 is overexpressed in ovarian carcinoma cell lines (OCC) compared with normal ovarian surface epithelium. As observed in other cancers, Six1 overexpression in OCC leads to increased A-type cyclin expression and increased proliferation. In addition, Six1 overexpression renders OCC resistant to tumor necrosis factor–related apoptosis inducing ligand (TRAIL)–mediated apoptosis, and Six1 knockdown in the TRAIL-resistant SKOV3 ovarian carcinoma line dramatically sensitizes the cells to TRAIL. Because inactivation of the TRAIL response has been linked to metastasis, and because antibodies and recombinant ligand that activate the TRAIL pathway are currently in clinical trials against ovarian carcinoma, we screened normal ovarian and carcinoma specimens for Six1 mRNA. Six1 was overexpressed in 50% of the early-stage (stage I) and 63% of the late-stage (stages II, III, and IV) ovarian carcinomas examined, with late-stage carcinomas expressing ∼3-fold higher Six1 mRNA levels on average compared with early-stage tumors. Importantly, in patients with late-stage disease, high Six1 expression was associated with significantly shortened survival (P = 0.0015). These data suggest that Six1 may contribute to ovarian epithelial carcinogenesis by simultaneously increasing proliferation and decreasing TRAIL-mediated apoptosis and imply that Six1 may be an important determinant of TRAIL therapy response that should be considered in patient selection for TRAIL-related clinical trials. [Cancer Res 2007;67(7):3036–42]
Data from Senescence Mediates Pituitary Hypoplasia and Restrains Pituitary Tumor Growth
Authors: Chesnokova Vera , Zonis Svetlana , Rubinek Tami , Yu Run , Ben-Shlomo Anat , Kovacs Kalman , Wawrowsky Kolja , Melmed Shlomo
Published: March 2023

Abstract
Understanding factors subserving pituitary cell proliferation enables understanding mechanisms underlying uniquely benign pituitary tumors. Pituitary tumor-transforming gene (Pttg) deletion results in pituitary hypoplasia, low pituitary cell proliferation rates, and rescue of pituitary tumor development in Rb+/− mice. Pttg−/− pituitary glands exhibit ARF/p53/p21-dependent senescence pathway activation evidenced by up-regulated p19, cyclin D1, and Bcl-2 protein levels and p53 stabilization. High pituitary p21 levels in the absence of PTTG were associated with suppressed cyclin-dependent kinase 2 activity, Rb phosphorylation, and cyclin A expression, all required for cell cycle progression. Although senescence-associated β-galactosidase was enhanced in Pttg-deficient pituitary glands, telomere lengths were increased. DNA damage signaling pathways were activated and aneuploidy was evident in the Pttg-deficient pituitary, triggering senescence-associated genes. To confirm the p21 dependency of decreased proliferation and senescence in the Pttg-null pituitary, mouse embryonic fibroblast (MEF) colony formation was tested in wild-type, Pttg−/−, Rb+/−, Rb+/−Pttg−/−, and Rb+/−Pttg−/−p21−/− cells. Rb+/−Pttg−/− MEFs, unlike Rb+/− cells, failed to produce colonies and exhibited high levels of senescence. p21 deletion from Rb+/−Pttg−/− MEFs enhanced anchorage-independent cell growth, accompanied by a marked decrease in senescence. As cell proliferation assessed by bromodeoxyuridine incorporation was higher in Rb+/−Pttg−/−p21−/− relative to Rb+/−Pttg−/− pituitary glands, p21-dependent senescence provoked by Pttg deletion may underlie pituitary hypoplasia and decreased tumor development in Rb+/−Pttg−/− mice. [Cancer Res 2007;67(21):10564–72]
Data from Krüppel-like Factor 4 Induces p27Kip1 Expression in and Suppresses the Growth and Metastasis of Human Pancreatic Cancer Cells
Authors: Wei Daoyan , Kanai Masahsi , Jia Zhiliang , Le Xiangdong , Xie Keping
Published: March 2023

Abstract
The zinc finger transcription factor Krüppel-like factor 4 (KLF4) has been implicated in both tumor suppression and progression. However, its function in pancreatic cancer has not been well characterized. Here, we show that pancreatic cancer cell lines expressed various levels of KLF4 RNA and protein. Ectopic expression of KLF4 by FG and BxPC-3 pancreatic cancer cells resulted in cell cycle arrest and marked inhibition of cell growth in vitro and attenuation of tumor growth and metastasis in an orthotopic mouse model. Overexpression of KLF4 also led to significant induction of p27Kip1 expression, at both the RNA and protein levels, in a dose- and time-dependent manner, indicating that KLF4 transcriptionally regulates the expression of p27Kip1. Chromatin immunoprecipitation assays consistently showed that KLF4 protein physically interacts with the p27Kip1 promoter. Promoter deletion and point mutation analyses indicated that a region between nucleotides −435 and −60 of the p27Kip1 promoter and intact of the three KLF4-binding sites within that region were required for the full induction of p27Kip1 promoter activity by KLF4. Our findings suggest that KLF4 transactivates p27Kip1 expression and inhibits the growth and metastasis of human pancreatic cancer. [Cancer Res 2008;68(12):4631–9]
Data from Gene Expression Signature of Human Cancer Cell Lines Treated with the Ras Inhibitor Salirasib (S-Farnesylthiosalicylic Acid)
Authors: Blum Roy , Elkon Ran , Yaari Shira , Zundelevich Adi , Jacob-Hirsch Jasmine , Rechavi Gideon , Shamir Ron , Kloog Yoel
Published: March 2023

Abstract
Deregulation of Ras pathways results in complex abnormalities of multiple signaling cascades that contribute to human malignancies. Ras is therefore considered an appropriate target for cancer therapy. In light of the complexity of the deregulated Ras pathway, it is important to decipher at the molecular level the response of cancer cells to Ras inhibitors that would reregulate it. In the present study, we used gene expression profiling as a robust method for the global dissection of gene expression alterations that resulted from treatment with the Ras inhibitor S-farnesylthiosalicylic acid (FTS; salirasib). Use of a ranking-based procedure, combined with functional analysis and promoter sequence analysis, enabled us to decipher the common and most prominent patterns of the transcriptional response of five different human cancer cell lines to FTS. Remarkably, the analysis identified a distinctive core transcriptional response to FTS that was common to all cancer cell lines tested. This signature fits well to a recently described deregulated Ras pathway signature that predicted sensitivity to FTS. Taken together, these studies provide strong support for the conclusion that FTS specifically reregulates defective Ras pathways in human tumor cells. Ras pathway reregulation by FTS was manifested by repression of E2F-regulated and NF-Y–regulated genes and of the transcription factor FOS (all of which control cell proliferation), repression of survivin expression (which blocks apoptosis), and induction of activating transcription factor–regulated and Bach2-regulated genes (which participate in translation and stress responses). Our results suggest that cancer patients with deregulated Ras pathway tumors might benefit from FTS treatment. [Cancer Res 2007;67(7):3320–8]
Data from Down-Regulation of Phosphoglucose Isomerase/Autocrine Motility Factor Results in Mesenchymal-to-Epithelial Transition of Human Lung Fibrosarcoma Cells
Authors: Funasaka Tatsuyoshi , Hu Huankai , Yanagawa Takashi , Hogan Victor , Raz Avraham
Published: March 2023

Abstract
Phosphoglucose isomerase (PGI) is one of the glycolytic enzymes and is a multifunctional enzyme that functions in glucose metabolism inside the cell while acting as a cytokine outside the cell, with properties that include autocrine motility factor (AMF) regulating tumor cell motility. Although there are many studies indicating that PGI/AMF has been implicated in progression of metastasis, no direct studies of the significance of exogenous PGI/AMF on tumor progression have been reported. Here, we report on the mesenchymal-to-epithelial transition (MET), which is the reverse phenomenon of the epithelial-to-mesenchymal transition that is associated with loss of cell polarity, loss of epithelia markers, and enhancement of cell motility essential for tumor cell invasion and metastasis. Mesenchymal human fibrosarcoma HT1080 cells, which have naturally high levels of endogenous and exogenous PGI/AMF, were stably transfected with PGI/AMF small interfering RNA (siRNA). The siRNA targeting human PGI/AMF down-regulated the endogenous PGI/AMF expression and completely extinguished the secretion of PGI/AMF in a human fibrosarcoma HT1080, whereas the control siRNA showed no effects. The PGI/AMF siRNA caused cells to change shape dramatically and inhibited cell motility and invasion markedly. Suppression of PGI/AMF led to a contact-dependent inhibition of cell growth. Those PGI/AMF siRNA-transfected cells showed epithelial phenotype. Furthermore, tumor cells with PGI/AMF deficiency lost their abilities to form tumor mass. This study identifies that MET in HT1080 human lung fibrosarcoma cells was initiated by down-regulation of the housekeeping gene product/cytokine PGI/AMF, and the results depicted here suggest a novel therapeutic target/modality for mesenchymal cancers. [Cancer Res 2007;67(9):4236–8]
Data from LOXL1 and LOXL4 Are Epigenetically Silenced and Can Inhibit Ras/Extracellular Signal-Regulated Kinase Signaling Pathway in Human Bladder Cancer
Authors: Wu Guojun , Guo Zhongmin , Chang Xiaofei , Kim Myoung Sook , Nagpal Jatin K. , Liu Junwei , Maki Joni M. , Kivirikko Kari I. , Ethier Stephen P. , Trink Barry , Sidransky David
Published: March 2023

Abstract
Promoter hypermethylation is one of the common mechanisms leading to gene silencing in various human cancers. Using a combination of pharmacologic unmasking and microarray techniques, we identified 59 candidate hypermethylated genes, including LOXL1, a lysyl oxidase-like gene, in human bladder cancer cells. We further showed that LOXL1 and LOXL4 are commonly silenced genes in human bladder cancer cells, and this silence is predominantly related to promoter methylation. We also found LOXL1 and LOXL4 gene methylation and loss of expression in primary bladder tumors. In addition, somatic mutations were identified in LOXL4, but not in LOXL1 in bladder cancer. Moreover, reintroduction of LOXL1 and LOXL4 genes into human bladder cancer cells leads to a decrease of colony formation ability. Further studies indicated that the overexpression of LOXL1 and LOXL4 could antagonize Ras in activating the extracellular signal-regulated kinase (ERK) signaling pathway. Thus, our current study suggests for the first time that lysyl oxidase-like genes can act as tumor suppressor genes and exert their functions through the inhibition of the Ras/ERK signaling pathway in human bladder cancer. [Cancer Res 2007;67(9):4123–9]
Data from CUL7 Is a Novel Antiapoptotic Oncogene
Authors: Kim Sam S. , Shago Mary , Kaustov Lilia , Boutros Paul C. , Clendening James W. , Sheng Yi , Trentin Grace A. , Barsyte-Lovejoy Dalia , Mao Daniel Y.L. , Kay Robert , Jurisica Igor , Arrowsmith Cheryl H. , Penn Linda Z.
Published: March 2023

Abstract
Using an expression cloning approach, we identify CUL7, a member of the cullin family, as a functional inhibitor of Myc-induced apoptosis. Deregulated expression of the Myc oncogene drives cellular proliferation yet also sensitizes cells to undergo p53-dependent and p53-independent apoptosis. Here, we report that CUL7 exerts its antiapoptotic function through p53. CUL7 binds directly to p53, and small interfering RNA–mediated knockdown of CUL7 results in the elevation of p53 protein levels. This antiapoptotic role of CUL7 enables this novel oncogene to cooperate with Myc to drive transformation. Deregulated ectopic expression of c-Myc and CUL7 promotes Rat1a cell growth in soft agar, and knockdown of CUL7 significantly blocks human neuroblastoma SHEP cell growth in an anchorage-independent manner. Furthermore, using public microarray data sets, we show that CUL7 mRNA is significantly overexpressed in non–small cell lung carcinoma and is associated with poor patient prognosis. We provide experimental evidence to show CUL7 is a new oncogene that cooperates with Myc in transformation by blocking Myc-induced apoptosis in a p53-dependent manner. [Cancer Res 2007;67(20):9616–22]
Data from Endostatin Binding to Ovarian Cancer Cells Inhibits Peritoneal Attachment and Dissemination
Authors: Yokoyama Yumi , Sedgewick Gerald , Ramakrishnan S.
Published: March 2023

Abstract
Ovarian cancer cells use integrins to attach to the peritoneal wall. Integrin α5β1 is also the target for the angiogenesis inhibitor, endostatin. Therefore, the ability of endostatin to competitively inhibit tumor cell seeding of the peritoneum was investigated. An imaging method was developed to determine early phases of peritoneal dissemination of ovarian cancer cells. Using this method, endostatin was found to bind ovarian cancer cells through integrin α5β1 and inhibit vessel cooption efficiently. Although both angiostatin and endostatin are potent inhibitors of tumor angiogenesis, peritoneal attachment and vessel cooption was blocked only by the endostatin. Knocking down the expression of integrins α5 and β1 in ovarian cancer cells interfered with endostatin-mediated inhibition of peritoneal seeding. Furthermore, adenovirus-mediated in situ expression of endostatin either inside the peritoneum or by the ovarian tumor cells inhibited peritoneal seeding and dissemination in vivo. Endostatin treatment also prevented primary ovarian cancer cells from attaching to mouse peritoneal wall. These studies show a paraendothelial mechanism by which endostatin can inhibit peritoneal dissemination of ovarian cancer cells and raises the possibility of intraperitoneal expression of endostatin to reduce recurrence. [Cancer Res 2007;67(22):10813–22]
Data from Mutation of Genes Affecting the RAS Pathway Is Common in Childhood Acute Lymphoblastic Leukemia
Authors: Case Marian , Matheson Elizabeth , Minto Lynne , Hassan Rosline , Harrison Christine J. , Bown Nick , Bailey Simon , Vormoor Josef , Hall Andrew G. , Irving Julie A.E.
Published: March 2023

Abstract
Deregulation of the RAS-RAF-mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK signaling cascade is often caused by somatic mutations in genes encoding proteins which influence the activity of this pathway and include NRAS, KRAS2, FLT3, PTPN11, and BRAF. We report the first comprehensive mutational screen of key exons of these genes in a large cohort of unselected acute lymphoblastic leukemia (ALL) cases at diagnosis (n = 86) and in a more selected cohort at disease recurrence (n = 47) using the sensitive method of denaturing high-performance liquid chromatography. We show that somatic mutations that deregulate the pathway constitute one of the most common genetic aberrations in childhood ALL (cALL), being found in 35% of diagnostic and 25% of relapse samples. In matched presentation/relapse pairs, mutations predominating at relapse could be shown to be present at very low levels at diagnosis using allele-specific PCR, thus implicating the mutated clone in disease progression. Importantly, in primary samples, we show that mutations are associated with activated ERK and differential cytotoxicity to MEK-ERK inhibitors was shown for some patients. Inhibitors of the pathway, which are currently undergoing clinical trial, may be a novel therapeutic option for cALL, particularly at relapse. [Cancer Res 2008;68(16):6803–9]
Data from Novel Noncatalytic Role for Caspase-8 in Promoting Src-Mediated Adhesion and Erk Signaling in Neuroblastoma Cells
Authors: Finlay Darren , Vuori Kristiina
Published: March 2023

Abstract
Neuroblastomas are extremely aggressive, although heterogeneous, cancers with a poor prognosis upon metastasis. Some evidence has suggested a correlative silencing of caspase-8 with MYCN amplification in neuroblastoma. A prognostic effect of this silencing, however, has been disputed. We report here hitherto undescribed roles for caspase-8 in the modulation of cell adhesion and subsequent activation of the Erk signaling pathway. Re-expression of caspase-8 in neuroblastoma cells lacking endogenous caspase-8 expression was found to promote cell adhesion to extracellular matrix and to activate adhesion-dependent signaling pathways, such as the Erk kinase cascade. This function of caspase-8 occurred irrespective of its proteolytic activity. Additionally, a pool of caspase-8 was shown to co-localize with the Src tyrosine kinase at the cellular periphery. Furthermore, our studies showed that caspase-8 forms a physical protein complex with Src via its death effector domains (DED) and maintains the complex in a detergent-soluble fraction. We also show that the DEDs of caspase-8 alone are necessary and sufficient to recreate the adhesive and biochemical phenotypes observed with the full-length protein, suggesting that caspase-8 may exert these effects via its association with Src. This protein complex association of caspase-8 and Src, and concomitant downstream signaling events, may help reconcile why a potential tumor suppressor such as caspase-8 is rarely absent in cancers. [Cancer Res 2007;67(24):11704–11]
Data from The Nuclear Receptor Interacting Factor-3 Transcriptional Coregulator Mediates Rapid Apoptosis in Breast Cancer Cells through Direct and Bystander-Mediated Events
Authors: Das Sharmistha , Nwachukwu Jerome C. , Li Dangsheng , Vulin Anthony I. , Martinez-Caballero Sonia , Kinnally Kathleen W. , Samuels Herbert H.
Published: March 2023

Abstract
We previously reported that amino acids 20 to 50 of nuclear receptor interacting factor-3 mediates rapid apoptosis in breast cancer cell lines but not in cells derived from other tissues. We refer to this short region as death domain-1 (DD1). Small interfering RNA studies indicated that DD1-mediated apoptosis is caspase-2 dependent. In this study, we examined DD1-mediated apoptosis in more detail and generated stable caspase-2 knockdown breast cancer cells. These cells are resistant to DD1-mediated apoptosis. Time-lapse movies suggested that DD1-mediated apoptosis also leads to a “bystander effect.” We found that within 5 h of DD1 expression, breast cancer cells release a factor(s) into the medium that leads to apoptosis of naive breast cancer cells or DD1-resistant cells (e.g., HeLa). The DD1-expressing caspase-2 knockdown cells also release a factor(s) that kills other cells, indicating that this effect is not dependent on the apoptogenic process. The bystander effect seems dependent on the production of reactive oxygen species (ROS). These and other studies indicate that DD1 expression in breast cancer cells leads to at least two death signals: one involving the rapid production of ROS and/or other soluble factors that directly or indirectly leads to a bystander effect and a second caspase-2–dependent process that leads to apoptosis in cells in which DD1 is expressed. [Cancer Res 2007;67(4):1775–82]
Data from PAX5/TEL Acts as a Transcriptional Repressor Causing Down-modulation of CD19, Enhances Migration to CXCL12, and Confers Survival Advantage in pre-BI Cells
Authors: Fazio Grazia , Palmi Chiara , Rolink Antonius , Biondi Andrea , Cazzaniga Giovanni
Published: March 2023

Abstract
PAX5 is a transcription factor essential for B-cell development. Recently, it has been found as a frequent target of aberrancies in childhood acute lymphoblastic leukemia (ALL; 30% of B cell ALL cases), showing monoallelic loss, point mutations, or chromosomal translocations. The role of these aberrancies is still poorly understood. We previously cloned the PAX5/TEL fusion gene in a patient affected by B-cell precursor ALL with a t(9;12) translocation. This is the first report investigating the molecular and functional roles of PAX5/TEL protein in vitro from murine wild-type pre-BI cells. We showed that PAX5/TEL protein acts as an aberrant transcription factor with repressor function, recruiting mSin3A, down-regulating B220, CD19, BLNK, MB-1, FLT3, and μ heavy chain expression, thus suggesting a block on B-cell differentiation. In a PAX5-deficient context, the presence of PAX5/TEL did not replace PAX5 functions. PAX5/TEL protein enhances cell migration towards CXCL12, with the overexpression of CXCR4. Moreover, the presence of the fusion gene overcomes interleukin-7 withdrawal and interferes with transforming growth factor-β1 pathway, inducing resistance and conferring cells an advantage in proliferation and survival. Thus, in vitro, the PAX5/TEL protein has a dominant effect on wild-type PAX5, interferes with the process of B-cell differentiation and migration, and induces resistance to apoptosis. Taken together, these phenomena likely represent key events in the process of B-cell transformation. [Cancer Res 2008;68(1):181–9]
Data from Tumor Necrosis Factor Receptor 1/c-Jun-NH2-Kinase Signaling Promotes Human Neoplasia
Authors: Zhang Jennifer Y. , Adams Amy E. , Ridky Todd W. , Tao Shiying , Khavari Paul A.
Published: March 2023

Abstract
The tumor necrosis factor α receptor (TNFR1) activates downstream effectors that include the mitogen-activated protein kinase kinase 7 (MKK7)/c-Jun-NH2-kinase (JNK)/activator protein 1 (AP1) cascade. Here, we report that JNK is activated in a majority of spontaneous human squamous cell carcinomas (SCC). JNK pathway induction bypassed cell cycle restraints induced by oncogenic Ras and cooperated with Ras to convert normal human epidermis into tumors indistinguishable from SCC, confirming its oncogenic potency in human tissue. Inhibiting MKK7, JNK, and AP1 as well as TNFR1 itself using genetic, pharmacologic, or antibody-mediated approaches abolished invasive human epidermal neoplasia in a tumor cell autonomous fashion. The TNFR1/MKK7/JNK/AP1 cascade thus promotes human neoplasia and represents a potential therapeutic target for human epithelial cancers. [Cancer Res 2007;67(8):3827–34]
Data from Hsp90 Inhibition Suppresses Mutant EGFR-T790M Signaling and Overcomes Kinase Inhibitor Resistance
Authors: Shimamura Takeshi , Li Danan , Ji Hongbin , Haringsma Henry J. , Liniker Elizabeth , Borgman Christa L. , Lowell April M. , Minami Yuko , McNamara Kate , Perera Samanthi A. , Zaghlul Sara , Thomas Roman K. , Greulich Heidi , Kobayashi Susumu , Chirieac Lucian R. , Padera Robert F. , Kubo Shigeto , Takahashi Masaya , Tenen Daniel G. , Meyerson Matthew , Wong Kwok-Kin , Shapiro Geoffrey I.
Published: March 2023

Abstract
The epidermal growth factor receptor (EGFR) secondary kinase domain T790M non–small cell lung cancer (NSCLC) mutation enhances receptor catalytic activity and confers resistance to the reversible tyrosine kinase inhibitors gefitinib and erlotinib. Currently, irreversible inhibitors represent the primary approach in clinical use to circumvent resistance. We show that higher concentrations of the irreversible EGFR inhibitor CL-387,785 are required to inhibit EGFR phosphorylation in T790M-expressing cells compared with EGFR mutant NSCLC cells without T790M. Additionally, CL-387,785 does not fully suppress phosphorylation of other activated receptor tyrosine kinases (RTK) in T790M-expressing cells. These deficiencies result in residual Akt and mammalian target of rapamycin (mTOR) activities. Full suppression of EGFR-mediated signaling in T790M-expressing cells requires the combination of CL-387,785 and rapamycin. In contrast, Hsp90 inhibition overcomes these limitations in vitro and depletes cells of EGFR, other RTKs, and phospho-Akt and inhibits mTOR signaling whether or not T790M is present. EGFR-T790M–expressing cells rendered resistant to CL-387,785 by a kinase switch mechanism retain sensitivity to Hsp90 inhibition. Finally, Hsp90 inhibition causes regression in murine lung adenocarcinomas driven by mutant EGFR (L858R) with or without T790M. However, efficacy in the L858R-T790M model requires a more intense treatment schedule and responses were transient. Nonetheless, these findings suggest that Hsp90 inhibitors may be effective in T790M-expressing cells and offer an alternative therapeutic strategy for this subset of lung cancers. [Cancer Res 2008;68(14):5827–38]
Data from A Small-Molecule E2F Inhibitor Blocks Growth in a Melanoma Culture Model
Authors: Ma Yihong , Kurtyka Courtney A. , Boyapalle Sandhya , Sung Shen-Shu , Lawrence Harshani , Guida Wayne , Cress W. Douglas
Published: March 2023

Abstract
HLM006474 was identified using a computer-based virtual screen and the known crystal structure of the DNA-bound E2F4/DP2 heterodimer. Treatment of multiple cell lines with HLM006474 resulted in the loss of intracellular E2F4 DNA-binding activity as measured by electrophoretic mobility shift assay within hours. Overnight exposure to HLM006474 resulted in down-regulation of total E2F4 protein as well as known E2F targets. The effects of HLM006474 treatment on different cell lines varied but included a reduction in cell proliferation and an increase in apoptosis. HLM006474 induced apoptosis in a manner distinct from cisplatin and doxorubicin. E2F4-null mouse embryonic fibroblasts were less sensitive than wild-type counterparts to the apoptosis-inducing activity of the compound, revealing its biological specificity. A375 cells were extremely sensitive to the apoptosis-inducing activity of the compound in two-dimensional culture, and HLM006474 was a potent inhibitor of melanocytes proliferation and subsequent invasion in a three-dimensional tissue culture model system. Together, these results suggest that interference with E2F activity using small molecules may have clinical application in cancer therapy. [Cancer Res 2008;68(15):6292–9]
Data from Imaging Pharmacodynamics of the α-Folate Receptor–Targeted Thymidylate Synthase Inhibitor BGC 945
Authors: Pillai Radhakrishna G. , Forster Martin , Perumal Meg , Mitchell Fraser , Leyton Julius , Aibgirhio Franklin I. , Golovko Oksana , Jackman Ann L. , Aboagye Eric O.
Published: March 2023

Abstract
The assessment of tissue-specific pharmacodynamics is desirable in the development of tumor-targeted therapies. Plasma deoxyuridine (dUrd) levels, a measure of systemic thymidylate synthase (TS) inhibition, has limited application for studying the pharmacodynamics of novel TS inhibitors targeted to the high affinity α-folate receptor (FR). Here, we have evaluated the utility of [18F]fluorothymidine positron emission tomography ([18F]FLT-PET) for imaging the tissue pharmacodynamics of BGC 945, an FR-targeted antifolate TS inhibitor; the nontargeted antifolate BGC 9331 was used for comparison. TS inhibition by both drugs induced a concentration-dependent increase in [3H]thymidine uptake in FR-positive human epidermoid KB cells. Membrane-associated equilibrative nucleoside transporter type 1 levels increased from 55,720 ± 6,101 to 118,700 ± 5,193 and 130,800 ± 10,800 per cell at 100 μg/mL of BGC 9331 and BGC 945, respectively, suggesting this as a potential mechanism of increased nucleoside uptake. In keeping with these in vitro findings, tumor [18F]FLT accumulation in KB xenografts increased by ≥2-fold after drug treatment with maximal levels at 1 to 4 hours and 4 to 24 hours after BGC 9331 and BGC 945 treatment, respectively. Of interest to FR targeting, BGC 9331, but not BGC 945, induced accumulation of [18F]FLT uptake in intestine, a proliferative and TS-responsive tissue. For both drugs, quantitative changes in tumor [18F]FLT uptake were associated with increased tumor dUrd levels. In conclusion, we have validated the utility of [18F]FLT-PET to image TS inhibition induced by antifolates and shown the tumor-specific activity of BGC 945. This imaging biomarker readout will be useful in the early clinical development of BGC 945. [Cancer Res 2008;68(10):3827–34]
Data from Transforming Growth Factor-β Activation Promotes Genetic Context–Dependent Invasion of Immortalized Melanocytes
Authors: Lo Roger S. , Witte Owen N.
Published: March 2023

Abstract
Accumulation of distinct sets of genetic/epigenetic alterations is thought to contribute to stepwise progression of human cutaneous melanomas. We found evidence of frequent tumor cell autonomous transforming growth factor-β (TGF-β) signal activation in both premalignant and malignant stages of human cutaneous melanoma histogenesis and investigated its potential causative roles using human organotypic skin cultures. PTEN deficiency and Braf activation, two common coincident genetic alterations found in primary cutaneous melanomas, were first introduced into human melanocytes previously immortalized by the SV40 large T antigen and telomerase. These changes individually supported anchorage-independent growth and conferred benign, hyperplastic growth in a skin-like environment. In addition, PTEN deficiency combined with Braf activation together induced a melanoma in situ–like phenotype without dermal invasion. Further addition of cell autonomous TGF-β activation in the context of PTEN deficiency and Braf activation promoted dermal invasion in skin cultures without significantly promoting proliferation in vitro and in vivo. This proinvasive phenotype of cell autonomous TGF-β activation is genetic context–dependent, as hyperactivating the TGF-β type I receptor without PTEN deficiency and Braf activation failed to induce an invasive behavior. Evidence of genetic interactions among PTEN deficiency, Braf activation, and cell autonomous TGF-β activation shows that distinct stages of human melanoma are genetically tractable in the proper tissue architecture. [Cancer Res 2008;68(11):4248–57]
Data from The Helix-Loop-Helix Protein Id1 Requires Cyclin D1 to Promote the Proliferation of Mammary Epithelial Cell Acini
Authors: Caldon C. Elizabeth , Swarbrick Alexander , Lee Christine S.L. , Sutherland Robert L. , Musgrove Elizabeth A.
Published: March 2023

Abstract
Overexpression of the helix-loop-helix (HLH) protein Id1 has been associated with metastasis in breast cancer, but its role in models of early breast tumorigenesis is not well characterized. We show that the down-regulation of endogenous Id1 via proteosomal degradation and relocalization from the nucleus to the cytoplasm is an early event in the formation of mammary epithelial acini. Overexpression of Id1 in both human MCF-10A and primary mouse mammary epithelial cells disrupted normal acinar development by increasing acinar volume. This occurred in an HLH domain–dependent fashion via an increase in S phase. Id1 overexpression also increased apoptosis leading to accelerated luminal clearance, and this was reversed by coexpression of the proto-oncogene Bcl2, leading to large, disorganized structures with filled lumina. Id1 overexpression was unable to increase the volume of cyclin D1−/− acini, indicating that Id1 is dependent on cyclin D1 for its proliferative effects. In summary, Id1 may contribute to early breast cancer by promoting excessive proliferation through cyclin D1. [Cancer Res 2008;68(8):3026–36]
Data from Role of the Polarity Determinant Crumbs in Suppressing Mammalian Epithelial Tumor Progression
Authors: Karp Cristina M. , Tan Ting Ting , Mathew Robin , Nelson Deidre , Mukherjee Chandreyee , Degenhardt Kurt , Karantza-Wadsworth Vassiliki , White Eileen
Published: March 2023

Abstract
Most tumors are epithelial-derived, and although disruption of polarity and aberrant cellular junction formation is a poor prognosticator in human cancer, the role of polarity determinants in oncogenesis is poorly understood. Using in vivo selection, we identified a mammalian orthologue of the Drosophila polarity regulator crumbs as a gene whose loss of expression promotes tumor progression. Immortal baby mouse kidney epithelial cells selected in vivo to acquire tumorigenicity displayed dramatic repression of crumbs3 (crb3) expression associated with disruption of tight junction formation, apicobasal polarity, and contact-inhibited growth. Restoration of crb3 expression restored junctions, polarity, and contact inhibition while suppressing migration and metastasis. These findings suggest a role for mammalian polarity determinants in suppressing tumorigenesis that may be analogous to the well-studied polarity tumor suppressor mechanisms in Drosophila. [Cancer Res 2008;68(11):4105–15]
Data from P-Glycoprotein–Mediated Resistance to Hsp90-Directed Therapy Is Eclipsed by the Heat Shock Response
Authors: McCollum Andrea K. , TenEyck Cynthia J. , Stensgard Bridget , Morlan Bruce W. , Ballman Karla V. , Jenkins Robert B. , Toft David O. , Erlichman Charles
Published: March 2023

Abstract
Despite studies that show the antitumor activity of Hsp90 inhibitors, such as geldanamycin (GA) and its derivative 17-allylamino-demethoxygeldanamycin (17-AAG), recent reports indicate that these inhibitors lack significant single-agent clinical activity. Resistance to Hsp90 inhibitors has been previously linked to expression of P-glycoprotein (P-gp) and the multidrug resistant (MDR) phenotype. However, the stress response induced by GA treatment can also cause resistance to Hsp90-targeted therapy. Therefore, we chose to further investigate the relative importance of P-gp and the stress response in 17-AAG resistance. Colony-forming assays revealed that high expression of P-gp could increase the 17-AAG IC50 6-fold in cells transfected with P-gp compared with parent cells. A549 cells selected for resistance to GA overexpressed P-gp, but verapamil did not reverse the resistance. These cells also overexpressed Hsp27, and Hsp70 was induced with 17-AAG treatment. When the GA and 17-AAG resistant cells were transfected with Hsp27 and/or Hsp70 small interfering RNA (siRNA), the 17-AAG IC50 decreased 10-fold compared with control transfected cells. Transfection with siRNA directed against Hsp27, Hsp70, or Hsp27 and Hsp70 also increased sensitivity to EC78, a purine scaffold-based Hsp90 inhibitor that is not a P-gp substrate. We conclude that P-gp may contribute, in part, to resistance to 17-AAG, but induction of stress response proteins, such as Hsp27 and Hsp70, by Hsp90-targeted therapy plays a larger role. Taken together, our results indicate that targeting of Hsp27 and Hsp70 should be exploited to increase the clinical efficacy of Hsp90-directed therapy. [Cancer Res 2008;68(18):7419–27]
Data from Complement-Dependent Tumor Cell Lysis Triggered by Combinations of Epidermal Growth Factor Receptor Antibodies
Authors: Dechant Michael , Weisner Wencke , Berger Sven , Peipp Matthias , Beyer Thomas , Schneider-Merck Tanja , Lammerts van Bueren Jeroen J. , Bleeker Wim K. , Parren Paul W.H.I. , van de Winkel Jan G.J. , Valerius Thomas
Published: March 2023

Abstract
Therapeutic monoclonal antibodies against the epidermal growth factor receptor (EGFR) have advanced the treatment of colon and head and neck cancer, and show great promise for the development of treatments for other solid cancers. Antibodies against EGFR have been shown to act via inhibition of receptor signaling and induction of antibody-dependent cellular cytoxicity. However, complement-dependent cytotoxicity, which is considered one of the most powerful cell killing mechanisms of antibodies, seems inactive for such antibodies. Here, we show a remarkable synergy for EGFR antibodies. Combinations of antibodies against EGFR were identified, which resulted in potent complement activation via the classic pathway and effective lysis of tumor cells. Studies on a large panel of antibodies indicated that the observed synergy is a general mechanism, which can be activated by combining human IgG1 antibodies recognizing different, nonoverlapping epitopes. Our findings show an unexpected quality of therapeutic EGFR antibodies, which may be exploited to develop novel and more effective treatments for solid cancers. [Cancer Res 2008;68(13):4998–5003]
Data from Aplidin, a Marine Organism–Derived Compound with Potent Antimyeloma Activity In vitro and In vivo
Authors: Mitsiades Constantine S. , Ocio Enrique M. , Pandiella Atanasio , Maiso Patricia , Gajate Consuelo , Garayoa Mercedes , Vilanova David , Montero Juan Carlos , Mitsiades Nicholas , McMullan Ciaran J. , Munshi Nikhil C. , Hideshima Teru , Chauhan Dharminder , Aviles Pablo , Otero Gabriel , Faircloth Glynn , Mateos M. Victoria , Richardson Paul G. , Mollinedo Faustino , San-Miguel Jesus F. , Anderson Kenneth C.
Published: March 2023

Abstract
Despite recent progress in its treatment, multiple myeloma (MM) remains incurable, thus necessitating identification of novel anti-MM agents. We report that the marine-derived cyclodepsipeptide Aplidin exhibits, at clinically achievable concentrations, potent in vitro activity against primary MM tumor cells and a broad spectrum of human MM cell lines, including cells resistant to conventional (e.g., dexamethasone, alkylating agents, and anthracyclines) or novel (e.g., thalidomide and bortezomib) anti-MM agents. Aplidin is active against MM cells in the presence of proliferative/antiapoptotic cytokines or bone marrow stromal cells and has additive or synergistic effects with some of the established anti-MM agents. Mechanistically, a short in vitro exposure to Aplidin induces MM cell death, which involves activation of p38 and c-jun NH2-terminal kinase signaling, Fas/CD95 translocation to lipid rafts, and caspase activation. The anti-MM effect of Aplidin is associated with suppression of a constellation of proliferative/antiapoptotic genes (e.g., MYC, MYBL2, BUB1, MCM2, MCM4, MCM5, and survivin) and up-regulation of several potential regulators of apoptosis (including c-JUN, TRAIL, CASP9, and Smac). Aplidin exhibited in vivo anti-MM activity in a mouse xenograft model. The profile of the anti-MM activity of Aplidin in our preclinical models provided the framework for its clinical testing in MM, which has already provided favorable preliminary results. [Cancer Res 2008;68(13):5216–25]