bluuebunny/crossref_metadata_2025 huggingface dataset:
Insulin Receptor Substrate-1 Suppresses Transforming Growth Factor-β1–Mediated Epithelial-Mesenchymal Transition
Authors: Shi Jian , Wang Dong-Mei , Wang Chun-Mei , Hu Ying , Liu Ai-Hua , Zhang Yong-Lian , Sun Bing , Song Jian-Guo
Published: September 2009

We investigated the regulatory effect of insulin receptor substrate-1 (IRS-1) on transforming growth factor-β1 (TGF-β1)–induced epithelial-mesenchymal transition (EMT). TGF-β1–induced EMT and cell migration in A549 cells are associated with a decrease in IRS-1 tyrosine phosphorylation and protein levels. Tissue microarray analysis of human lung carcinoma shows a correlation between IRS-1 protein levels and E-cadherin protein levels. High IRS-1 levels coexist with high E-cadherin levels, whereas low IRS-1 levels coexist with low E-cadherin levels, implying a possibility that IRS-1 protein levels may be linked with EMT. Surprisingly, overexpression of IRS-1 in A549 cells completely blocked TGF-β1–induced EMT and cell migration, inhibited TGF-β1–mediated expression of snail and slug genes, and abolished TGF-β1–mediated repression of E-cadherin promoter activity. In contrast, IRS-1 knockdown by RNAi increased the expression of snail and slug genes and induced EMT. Inhibition of protein tyrosine phosphatase with sodium vanadate, which greatly increased the levels of tyrosine-phosphorylated IRS-1, suppressed TGF-β1–induced actin remodeling and cell morphologic changes. These results show for the first time that TGF-β1 induces EMT through mechanisms involving the modulation of IRS-1 signaling, and that IRS-1 functions as a critical EMT suppressor that suppresses TGF-β1–induced EMT via inhibition of snail and slug expression. [Cancer Res 2009;69(18):7180–7]
Contribution of Granulocyte Colony-Stimulating Factor to the Acute Mobilization of Endothelial Precursor Cells by Vascular Disrupting Agents
Authors: Shaked Yuval , Tang Terence , Woloszynek Jill , Daenen Laura G. , Man Shan , Xu Ping , Cai Shi-Rong , Arbeit Jeffrey M. , Voest Emile E. , Chaplin David J. , Smythe Jon , Harris Adrian , Nathan Paul , Judson Ian , Rustin Gordon , Bertolini Francesco , Link Daniel C. , Kerbel Robert S.
Published: September 2009

Vascular disrupting agents (VDA) cause acute shutdown of abnormal established tumor vasculature, followed by massive intratumoral hypoxia and necrosis. However, a viable rim of tumor tissue invariably remains from which tumor regrowth rapidly resumes. We have recently shown that an acute systemic mobilization and homing of bone marrow–derived circulating endothelial precursor (CEP) cells could promote tumor regrowth following treatment with either a VDA or certain chemotherapy drugs. The molecular mediators of this systemic reactive host process are unknown. Here, we show that following treatment of mice with OXi-4503, a second-generation potent prodrug derivative of combretastatin-A4 phosphate, rapid increases in circulating plasma vascular endothelial growth factor, stromal derived factor-1 (SDF-1), and granulocyte colony-stimulating factor (G-CSF) levels are detected. With the aim of determining whether G-CSF is involved in VDA-induced CEP mobilization, mutant G-CSF-R−/− mice were treated with OXi-4503. We found that as opposed to wild-type controls, G-CSF-R−/− mice failed to mobilize CEPs or show induction of SDF-1 plasma levels. Furthermore, Lewis lung carcinomas grown in such mice treated with OXi-4503 showed greater levels of necrosis compared with tumors treated in wild-type mice. Evidence for rapid elevations in circulating plasma G-CSF, vascular endothelial growth factor, and SDF-1 were also observed in patients with VDA (combretastatin-A4 phosphate)-treated cancer. These results highlight the possible effect of drug-induced G-CSF on tumor regrowth following certain cytotoxic drug therapies, in this case using a VDA, and hence G-CSF as a possible therapeutic target. [Cancer Res 2009;69(19):7524–8]
Irradiation Alters Selection for Oncogenic Mutations in Hematopoietic Progenitors
Authors: Marusyk Andriy , Casás-Selves Matias , Henry Curtis J. , Zaberezhnyy Vadym , Klawitter Jelena , Christians Uwe , DeGregori James
Published: September 2009

Exposure to ionizing radiation and other DNA-damaging carcinogens is strongly associated with induction of malignancies. Prevailing paradigms attribute this association to the induction of oncogenic mutations, as the incidence of oncogenic events is thought to limit initiation and progression of cancers. On the other hand, random mutagenic and genotoxic effects of irradiation are likely to alter progenitor cell populations and the microenvironment, thus altering the selective effects of oncogenic mutations. Using competitive bone marrow transplantation experiments in mice, we show that ionizing irradiation leads to a persistent decline in the numbers and fitness of hematopoietic stem cells, in part resulting from persistent induction of reactive oxygen species. Previous irradiation dramatically alters the selective effects of some oncogenic mutations, substantially inhibiting clonal expansion and leukemogenesis driven by Bcr-Abl or activated N-Ras oncogenes but enhancing the selection for and leukemogenesis driven by the activated Notch1 mutant ICN. Irradiation-dependent selection for ICN expression occurs in a hematopoietic stem cell–enriched pool, which should facilitate the accumulation of additional oncogenic events at a committed T-progenitor stage critical for formation of T-lymphocytic leukemia stem cells. Enhancement of ICN-driven selection and leukemogenesis by previous irradiation is in part non–cell autonomous, as partial restoration of normal hematopoiesis can reverse these effects of irradiation. These studies show that irradiation substantially alters the adaptive landscape in hematopoietic progenitors and suggest that the causal link between irradiation and carcinogenesis might involve increased selection for particular oncogenic mutations. [Cancer Res 2009;69(18):7262–9]
The Receptor Tyrosine Kinase EPHB4 Has Tumor Suppressor Activities in Intestinal Tumorigenesis
Authors: Dopeso Higinio , Mateo-Lozano Silvia , Mazzolini Rocco , Rodrigues Paulo , Lagares-Tena Laura , Ceron Julian , Romero Jordi , Esteves Marielle , Landolfi Stefania , Hernández-Losa Javier , Castaño Julio , Wilson Andrew J. , Ramon y Cajal Santiago , Mariadason John M. , Schwartz Simo , Arango Diego
Published: September 2009

Colorectal cancer is the second cause of cancer-related death in the western world, and although the genetic and molecular mechanisms involved in the initiation and progression of these tumors are among the best characterized, there are significant gaps in our understanding of this disease. The role of EPHB signaling in colorectal cancer has only recently been realized. Here, we use animal models to investigate the role of EphB4 in intestinal tumorigenesis. Modulation of EPHB4 levels in colon cancer cell lines resulted in significant differences in tumor growth in a xenograft model, with low levels of EPHB4 associated with faster growth. In addition, using a genetic model of intestinal tumorigenesis where adenomatous polyposis coli (Apc) mutations lead to initiation of the tumorigenic process (Apcmin mice), we show that inactivation of a single allele of EphB4 results in higher proliferation in both the normal epithelium and intestinal tumors, significantly larger tumors in the small intestine, and a 10-fold increase in the number of tumors in the large intestine. This was associated with a 25% reduction in the lifespan of Apcmin mice (P < 0.0001). Gene expression analysis showed that EphB4 mutations result in a profound transcriptional reprogramming, affecting genes involved in cell proliferation, remodeling of the extracellular matrix, and cell attachment to the basement membrane among other functional groups of genes. Importantly, in agreement with the expression profiling experiments, using an in vitro assay, we show that loss of EPHB4 in colon cancer cells results in a significantly increased potential to invade through a complex extracellular matrix. Collectively, these results indicate that EphB4 has tumor suppressor activities and that regulation of cell proliferation, extracellular matrix remodeling, and invasive potential are important mechanisms of tumor suppression. [Cancer Res 2009;69(18):7430–8]
BCL9 Promotes Tumor Progression by Conferring Enhanced Proliferative, Metastatic, and Angiogenic Properties to Cancer Cells
Authors: Mani Mala , Carrasco Daniel E. , Zhang Yunyu , Takada Kohichi , Gatt Moshe E. , Dutta-Simmons Jui , Ikeda Hiroshi , Diaz-Griffero Felipe , Pena-Cruz Victor , Bertagnolli Monica , Myeroff Lois L. , Markowitz Sanford D. , Anderson Kenneth C. , Carrasco Daniel R.
Published: September 2009

Several components of the Wnt signaling cascade have been shown to function either as tumor suppressor proteins or as oncogenes in multiple human cancers, underscoring the relevance of this pathway in oncogenesis and the need for further investigation of Wnt signaling components as potential targets for cancer therapy. Here, using expression profiling analysis as well as in vitro and in vivo functional studies, we show that the Wnt pathway component BCL9 is a novel oncogene that is aberrantly expressed in human multiple myeloma as well as colon carcinoma. We show that BCL9 enhances β-catenin–mediated transcriptional activity regardless of the mutational status of the Wnt signaling components and increases cell proliferation, migration, invasion, and the metastatic potential of tumor cells by promoting loss of epithelial and gain of mesenchymal-like phenotype. Most importantly, BCL9 knockdown significantly increased the survival of xenograft mouse models of cancer by reducing tumor load, metastasis, and host angiogenesis through down-regulation of c-Myc, cyclin D1, CD44, and vascular endothelial growth factor expression by tumor cells. Together, these findings suggest that deregulation of BCL9 is an important contributing factor to tumor progression. The pleiotropic roles of BCL9 reported in this study underscore its value as a drug target for therapeutic intervention in several malignancies associated with aberrant Wnt signaling. [Cancer Res 2009;69(19):7577–86]
c-Jun Protects Hypoxia-Inducible Factor-1α from Degradation via Its Oxygen-Dependent Degradation Domain in a Nontranscriptional Manner
Authors: Yu Bing , Miao Ze-Hong , Jiang Yi , Li Mei-Hong , Yang Na , Li Ting , Ding Jian
Published: September 2009

Although hypoxia-inducible factor-1α (HIF-1α) has long been intensively investigated as a drug target by interfering with its expression or transcriptional function, the regulatory mechanisms of HIF-1α remain to be further clarified. We report here that c-Jun associates with HIF-1α via its oxygen-dependent degradation domain, masks the sites for ubiquitination, and thus protects HIF-1α from proteasome-executing degradation. All of these together resulted in the stabilization and accumulation of HIF-1α, consequently promoting the transcription of its target gene and driving angiogenesis-related events. The stabilization of HIF-1α was dependent on the domains of c-Jun for DNA binding and heterodimerization but independent of the Ser63/73 phosphorylation that is critical for transcriptional function. These findings highlight a previously unrecognized nontranscriptional function of c-Jun on the one hand and a distinct regulatory mechanism of HIF-1α activity on the other, consequently offering profound mechanistic insights into multiple events simultaneously involving both c-Jun and HIF-1α in tumor progression. [Cancer Res 2009;69(19):7704–12]
A Genetic Variant of Aurora Kinase A Promotes Genomic Instability Leading to Highly Malignant Skin Tumors
Authors: Torchia Enrique C. , Chen Yiyun , Sheng Hong , Katayama Hiroshi , Fitzpatrick James , Brinkley William R. , Caulin Carlos , Sen Subrata , Roop Dennis R.
Published: September 2009

Aurora kinase A (Aurora-A) belongs to a highly conserved family of mitotis-regulating serine/threonine kinases implicated in epithelial cancers. Initially we examined Aurora-A expression levels at different stages of human skin cancer. Nuclear Aurora-A was detected in benign lesions and became more diffused but broadly expressed in well and poorly differentiated squamous cell carcinomas (SCC), indicating that Aurora-A deregulation may contribute to SCC development. To mimic the overexpression of Aurora-A observed in human skin cancers, we established a gene-switch mouse model in which the human variant of Aurora-A (Phe31Ile) was expressed in the epidermis upon topical application of the inducer RU486 (Aurora-AGS). Overexpression of Aurora-A alone or in combination with the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA), did not result in SCC formation in Aurora-AGS mice. Moreover, Aurora-A overexpression in naive keratinocytes resulted in spindle defects in vitro and marked cell death in vivo, suggesting that the failure of Aurora-A to initiate tumorigenesis was due to induction of catastrophic cell death. However, Aurora-A overexpression combined with exposure to TPA and the mutagen 7,12-dimethylbenz(a)anthracene accelerated SCC development with greater metastastic activity than control mice, indicating that Aurora-A cannot initiate skin carcinogenesis but rather promotes the malignant conversion of skin papillomas. Further characterization of SCCs revealed centrosome amplification and genomic alterations by array CGH analysis, indicating that Aurora-A overexpression induces a high level of genomic instability that favors the development of aggressive and metastatic tumors. Our findings strongly implicate Aurora-A overexpression in the malignant progression of skin tumors and suggest that Aurora-A may be an important therapeutic target. [Cancer Res 2009;69(18):7207–15]
Epigenetic Loss of Mucosa-Associated Lymphoid Tissue 1 Expression in Patients with Oral Carcinomas
Authors: Chiba Tadashige , Maeda Genta , Kawashiri Shuichi , Kato Koroku , Imai Kazushi
Published: September 2009

Mucosa-associated lymphoid tissue 1 (MALT1), which is located in a genomic region that encodes unknown tumor suppressor gene(s), activates nuclear factor-κB in lymphocyte lineages. However, its expression and role in the pathology of malignant tumors of epithelial origin is not known. In the present study, we examined MALT1 expression and its implications for the pathology of oral carcinomas. Immunostaining localized MALT1 in the nucleus of normal oral epithelial cells, but the expression was absent in 45.0% of carcinomas (49 of 109 cases) especially at the invasive front. The loss of expression was correlated with tumor recurrence (P = 0.007) and poor patient survival (P < 0.001), and it was an independent prognostic determinant (P < 0.001). MALT1-negative carcinomas exhibited microsatellite instability at the MALT1 locus and a specific cytosine methylation positioned at −256 from the gene, and the expression was recovered by demethylation treatment. In contrast to lymphocyte lineages, carcinoma cells showed MALT1 located at the nucleus independent of its domain structures, and its loss of expression induced the epithelial-mesenchymal transition. These results show that MALT1 is expressed in the nucleus of oral epithelial cells and that its expression is epigenetically inactivated during tumor progression, suggesting that the detection of MALT1 expression is a useful predictive and prognostic determinant in the clinical management of oral carcinomas. [Cancer Res 2009;69(18):7216–23]
A Risk Variant in an miR-125b Binding Site in BMPR1B Is Associated with Breast Cancer Pathogenesis
Authors: Sætrom Pål , Biesinger Jacob , Li Sierra M. , Smith David , Thomas Laurent F. , Majzoub Karim , Rivas Guillermo E. , Alluin Jessica , Rossi John J. , Krontiris Theodore G. , Weitzel Jeffrey , Daly Mary B. , Benson Al B. , Kirkwood John M. , O'Dwyer Peter J. , Sutphen Rebecca , Stewart James A. , Johnson David , Larson Garrett P.
Published: September 2009

MicroRNAs regulate diverse cellular processes and play an integral role in cancer pathogenesis. Genomic variation within miRNA target sites may therefore be important sources for genetic differences in cancer risk. To investigate this possibility, we mapped HapMap single nucleotide polymorphisms (SNP) to putative miRNA recognition sites within genes dysregulated in estrogen receptor–stratified breast tumors and used local linkage disequilibirum patterns to identify high-ranking SNPs in the Cancer Genetic Markers of Susceptibility (CGEMS) breast cancer genome-wide association study for further testing. Two SNPs, rs1970801 and rs11097457, scoring in the top 100 from the CGEMS study, were in strong linkage disequilibrium with rs1434536, an SNP that resides within a miR-125b target site in the 3′ untranslated region of the bone morphogenic receptor type 1B (BMPR1B) gene encoding a transmembrane serine/threonine kinase. We validated the CGEMS association findings for rs1970801 in an independent cohort of admixture-corrected cases identified from families with multiple case histories. Subsequent association testing of rs1434536 for these cases and CGEMS controls with imputed genotypes supported the association. Furthermore, luciferase reporter assays and overexpression of miR-125b–mimics combined with quantitative reverse transcription-PCR showed that BMPR1B transcript is a direct target of miR-125b and that miR-125b differentially regulates the C and T alleles of rs1434536. These results suggest that allele-specific regulation of BMPR1B by miR-125b explains the observed disease risk. Our approach is general and can help identify and explain the mechanisms behind disease association for alleles that affect miRNA regulation. [Cancer Res 2009;69(18):7459–65]
mTOR Signal and Hypoxia-Inducible Factor-1α Regulate CD133 Expression in Cancer Cells
Authors: Matsumoto Kazuko , Arao Tokuzo , Tanaka Kaoru , Kaneda Hiroyasu , Kudo Kanae , Fujita Yoshihiko , Tamura Daisuke , Aomatsu Keiichi , Tamura Tomohide , Yamada Yasuhide , Saijo Nagahiro , Nishio Kazuto
Published: September 2009

The underlying mechanism regulating the expression of the cancer stem cell/tumor-initiating cell marker CD133/prominin-1 in cancer cells remains largely unclear, although knowledge of this mechanism would likely provide important biological information regarding cancer stem cells. Here, we found that the inhibition of mTOR signaling up-regulated CD133 expression at both the mRNA and protein levels in a CD133-overexpressing cancer cell line. This effect was canceled by a rapamycin-competitor, tacrolimus, and was not modified by conventional cytotoxic drugs. We hypothesized that hypoxia-inducible factor-1α (HIF-1α), a downstream molecule in the mTOR signaling pathway, might regulate CD133 expression; we therefore investigated the relation between CD133 and HIF-1α. Hypoxic conditions up-regulated HIF-1α expression and inversely down-regulated CD133 expression at both the mRNA and protein levels. Similarly, the HIF-1α activator deferoxamine mesylate dose-dependently down-regulated CD133 expression, consistent with the effects of hypoxic conditions. Finally, the correlations between CD133 and the expressions of HIF-1α and HIF-1β were examined using clinical gastric cancer samples. A strong inverse correlation (r = −0.68) was observed between CD133 and HIF-1α, but not between CD133 and HIF-1β. In conclusion, these results indicate that HIF-1α down-regulates CD133 expression and suggest that mTOR signaling is involved in the expression of CD133 in cancer cells. Our findings provide a novel insight into the regulatory mechanisms of CD133 expression via mTOR signaling and HIF-1α in cancer cells and might lead to insights into the involvement of the mTOR signal and oxygen-sensitive intracellular pathways in the maintenance of stemness in cancer stem cells. [Cancer Res 2009;69(18):7160–4]
Clear Differences in Levels of a Formaldehyde-DNA Adduct in Leukocytes of Smokers and Nonsmokers
Authors: Wang Mingyao , Cheng Guang , Balbo Silvia , Carmella Steven G. , Villalta Peter W. , Hecht Stephen S.
Published: September 2009

Formaldehyde is considered carcinogenic to humans by the IARC, but there are no previous reports of formaldehyde-DNA adducts in humans. In this study, we used liquid chromatography-electrospray ionization-tandem mass spectrometry to quantify the formaldehyde-DNA adduct N6-hydroxymethyldeoxyadenosine (N6-HOMe-dAdo) in leukocyte DNA samples from 32 smokers of ≥10 cigarettes per day and 30 nonsmokers. Clear peaks coeluting with the internal standard in two different systems were seen in samples from smokers but rarely in nonsmokers. N6-HOMe-dAdo was detected in 29 of 32 smoker samples (mean ± SD, 179 ± 205 fmol/μmol dAdo). In contrast, it was detected in only 7 of 30 nonsmoker samples (15.5 ± 33.8 fmol/μmol dAdo; P < 0.001). The results of this study show remarkable differences between smokers and nonsmokers in levels of a leukocyte formaldehyde-DNA adduct, suggesting a potentially important and previously unrecognized role for formaldehyde as a cause of cancer induced by cigarette smoking. [Cancer Res 2009;69(18):7170–4]
Inactivation of the Carney Complex Gene 1 (Protein Kinase A Regulatory Subunit 1A) Inhibits SMAD3 Expression and TGFβ-Stimulated Apoptosis in Adrenocortical Cells
Authors: Ragazzon Bruno , Cazabat Laure , Rizk-Rabin Marthe , Assie Guillaume , Groussin Lionel , Fierrard Hélène , Perlemoine Karine , Martinez Antoine , Bertherat Jérôme
Published: September 2009

The cyclic AMP signaling pathway can be altered at multiple levels in endocrine tumors. Its central component is the protein kinase A (PKA). Carney complex (CNC) is a hereditary multiple neoplasia syndrome resulting from inactivating mutations of the gene encoding the PKA type I α regulatory subunit (PRKAR1A). Primary pigmented nodular adrenocortical disease is the most frequent endocrine tumor of CNC. Transforming growth factor β (TGFβ) regulates adrenal cortex physiology and signals through SMAD2/3. We used an interference approach to test the effects of PRKAR1A inactivation on PKA and TGFβ pathways and on apoptosis in adrenocortical cells. PRKAR1A silencing stimulates PKA activity and increases transcriptional activity of a PKA reporter construct and expression of the endogenous PKA target, NR4A2, under basal conditions or after forskolin stimulation. PRKAR1A inactivation also decreased SMAD3 mRNA and protein levels via PKA, altering the cellular response to TGFβ. SMAD3 expression was also inhibited by adrenocorticorticotropic hormone in the mouse adrenal gland and by forskolin in H295R cells. TGFβ stimulates apoptosis in H295R cells, and this effect was counteracted by PRKAR1A inactivation. PRKAR1A silencing decreased the percentage of apoptotic cells and the cleavage of apoptosis mediators [caspase-3, poly(ADP-ribose) polymerase, and lamin A/C]. Inactivating mutations of PRKAR1A observed in adrenocortical tumors alter SMAD3, leading to resistance to TGFβ-induced apoptosis. This cross-talk between the PKA and the TGFβ signaling pathways reveals a new mechanism of endocrine tumorigenesis. [Cancer Res 2009;69(18):7278–84]
Structural Basis for the Inhibition of Human 5,10-Methenyltetrahydrofolate Synthetase by N10-Substituted Folate Analogues
Authors: Wu Dong , Li Yang , Song Gaojie , Cheng Chongyun , Zhang Rongguang , Joachimiak Andrzej , Shaw Neil , Liu Zhi-Jie
Published: September 2009

5,10-Methenyltetrahydrofolate synthetase (MTHFS) regulates the flow of carbon through the one-carbon metabolic network, which supplies essential components for the growth and proliferation of cells. Inhibition of MTHFS in human MCF-7 breast cancer cells has been shown to arrest the growth of cells. Absence of the three-dimensional structure of human MTHFS (hMTHFS) has hampered the rational design and optimization of drug candidates. Here, we report the structures of native hMTHFS, a binary complex of hMTHFS with ADP, hMTHFS bound with the N5-iminium phosphate reaction intermediate, and an enzyme-product complex of hMTHFS. The N5-iminium phosphate captured for the first time in our crystal structure unravels a unique strategy used by hMTHFS for recognition of the substrate and provides structural basis for the regulation of enzyme activity. Binding of N10-substituted folate analogues places Y152 in the middle of the channel connecting ATP binding site with the substrate binding pocket, precluding the positioning of γ-phosphate for a nucleophilic attack. Using the structures of hMTHFS as a guide, we have probed the role of residues surrounding the active site in catalysis by mutagenesis. The ensemble of hMTHFS structures and the mutagenesis data yield a coherent picture of the MTHFS active site, determinants of substrate specificity, and new insights into the mechanism of inhibition of hMTHFS. [Cancer Res 2009;69(18):7294–301]
Immunogenicity of the Hu14.18-IL2 Immunocytokine Molecule in Adults With Melanoma and Children With Neuroblastoma
Authors: Hank Jacquelyn A. , Gan Jacek , Ryu Hyunji , Ostendorf Amy , Stauder Michael C. , Sternberg Adam , Albertini Mark , Lo Kin-Ming , Gillies Stephen D. , Eickhoff Jens , Sondel Paul M.
Published: September 2009

Purpose: Immunocytokine (IC) hu14.18-IL2 is a fusion protein of humanized antidisialoganglioside (GD2) antibody (hu14.18) and interleukin (IL)-2. Sixty-one melanoma and neuroblastoma patients received IC in phase I/Ib studies. Patient sera were examined in ELISA to determine if an anti-IC antibody response occurred during treatment.

Experimental Design: Serum was assayed for anti-idiotypic antibody (anti-id Ab) based on ability to bridge biotinylated hu14.18 to plate-bound hu14.18 and ability to inhibit binding of hu14.18 to GD2 antigen and/or murine anti-idiotypic antibody. ELISA was also used to detect antibodies to the Fc-IL2 end of hu14.18-IL2.

Results: Thirty-two patients (52%) developed an anti-idiotypic antibody response (absorbance, >0.7) in the bridge ELISA. Twelve patients (20%) had an intermediate response, whereas 17 patients (28%) were negative (adsorbance, <0.3). The development of antibody to hu14.18-IL2 detected in the bridge ELISA was not related to the dose of hu14.18-IL2. Twenty of 33 adult patients (61%) demonstrated an anti-idiotypic antibody response based on binding inhibition ELISA. The anti-idiotypic response was inversely correlated (P < 0.002) with IC measured during the second course of treatment, indicating that development of anti-idiotypic antibodies interfered with detection of circulating hu14.18-IL2. All patients developed some inhibitory activity in the binding inhibition assay designed to detect antibodies to the Fc-IL2 region of the IC. There was a positive correlation between the peak serum level of IC in course 1 and the anti–Fc-IL2 response.

Conclusions: Patients treated with hu14.18-IL2 developed anti-idiotypic antibodies and anti Fc-IL2 antibodies. No association was seen between development of anti-IC antibodies and clinical toxicity. (Clin Cancer Res 2009;15(18):5923–30)
Induction of Bim Expression Contributes to the Antitumor Synergy Between Sorafenib and Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase Inhibitor CI-1040 in Hepatocellular Carcinoma
Authors: Ou Da-Liang , Shen Ying-Chun , Liang Ja-Der , Liou Jun-Yang , Yu Sung-Liang , Fan Hsiang-Hsuan , Wang Da-Sheng , Lu Yen-Shen , Hsu Chiun , Cheng Ann-Lii
Published: September 2009

Purpose: Sorafenib has proved survival benefit for patients with advanced hepatocellular carcinoma (HCC). This study explored whether the efficacy of sorafenib can be improved by adding the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor CI-1040 to vertically block the Raf/MEK/ERK pathway.

Experimental Design: The growth inhibitory effects of sorafenib and CI-1040 were tested in HCC cell lines (Huh-7 and Hep3B) and human umbilical vascular endothelial cells (HUVEC). The potential synergistic growth inhibitory effects were measured by median effect analysis. Apoptosis was measured by flow cytometry. The effects on ERK phosphorylation and levels of apoptosis regulatory proteins were measured by Western blotting. The in vivo antitumor activity of sorafenib and CI-1040 were tested in xenograft HCC models.

Results: Combination of sorafenib and CI-1040 synergistically inhibited ERK phosphorylation and cell growth and induced apoptosis in both HCC cells and HUVECs. Increased expression of Bim protein, which correlated with the extent of ERK inhibition, was found in both HCC cells and HUVECs. Knockdown of Bim expression by small interfering RNA partially abrogated the synergistic proapoptotic effects of sorafenib and CI-1040. Combination therapy inhibited tumor growth significantly better than either single agent in the xenograft models.

Conclusion: The antitumor effects of sorafenib in HCC can be improved by vertical blockade of Raf/MEK/ERK signaling with CI-1040. (Clin Cancer Res 2009;15(18):5820–8)
C-Raf Is Associated with Disease Progression and Cell Proliferation in a Subset of Melanomas
Authors: Jilaveanu Lucia B. , Zito Christopher R. , Aziz Saadia A. , Conrad Patricia J. , Schmitz John C. , Sznol Mario , Camp Robert L. , Rimm David L. , Kluger Harriet M.
Published: September 2009

Purpose: Raf-kinases include three major isoforms. Although the role of B-Raf in melanoma is well established, little is known about C-Raf. We studied effects of C-Raf knockdown in vitro and assessed expression of C-Raf in a large cohort of melanomas and nevi.

Experimental Design: Using specific siRNAs, we knocked down C-Raf expression, and determined the effect on viability, MAP extracellular signal-regulated kinase (ERK)/ERK kinase signaling, and apoptosis in seven melanoma cell lines. We determined the IC50 of the C-Raf inhibitors sorafenib and GW5074, and studied the effects of GW5074 on cell signaling. Using an automated method to measure in situ protein expression, we quantified C-Raf expression in 263 nevi and 523 melanomas.

Results: C-Raf was knocked down in three cell lines with detectable phospho-C-Raf, resulting in decreased viability in two of the three (YULAC and YUROB). This resulted in decreased Bcl-2 expression and phospho-Bad cleavage, without affecting phospho-MEK and phospho-ERK. Sensitivity to sorafenib and GW5074 varied. GW5074 inhibited mitogen-activated protein kinase signaling without Bcl-2 and phospho-Bad down-regulation. C-Raf was highly expressed in melanomas compared with nevi (P < 0.0001), and no nevi had high C-Raf expression. C-Raf expression was higher in metastatic than primary specimens (P = 0.0225).

Conclusions: C-Raf siRNA knock-down results in decreased viability of YULAC (B-RafV600K) and YUROB (B-RafWT) melanoma cells, likely mediated by Bcl-2 inhibition rather than mitogen-activated protein kinase inhibition. Cotargeting C-Raf and parallel pathways might be an effective therapeutic approach for melanoma. C-Raf expression is up-regulated in a subset of melanomas but not in nevi, suggesting that it might be a valuable diagnostic marker and therapeutic target. (Clin Cancer Res 2009;15(18):5704–13)
Putative Tumor-Suppressive Function of Krüppel-Like Factor 4 in Primary Lung Carcinoma
Authors: Hu Wenxian , Hofstetter Wayne L. , Li Hong , Zhou Yanbin , He Yong , Pataer Abujiang , Wang Li , Xie Keping , Swisher Stephen G. , Fang Bingliang
Published: September 2009

Purpose: Krüppel-like factor 4 (KLF4) is a zinc-finger protein that plays important roles in stem cells and the development of gastric cancers. However, the role of KLF4 in primary lung cancer is unknown. The purpose of this study is to determine possible roles of KLF4 in lung cancer.

Experimental Design: The KLF4 expression in primary lung cancer tissues and case-matched normal lung tissues were determined by protein and mRNA analyses. The effects of KLF4 on cell proliferation, clonogenic formation, and cell cycle progression were determined in cultured lung cancer cells or bronchial epithelial cells after enforced KLF4 overexpression or small interfering RNA knockdown. The in vivo antitumor activity of KLF4 was evaluated by using stably transfected lung cancer cells and by adenovector-mediated gene delivery. The effect of KLF4 in regulating p21 and cyclin D1 was also evaluated.

Results: KLF4 protein and mRNA levels were dramatically decreased in most primary lung tumors compared with in case-matched normal lung tissues. Enforced expression of KLF4 resulted in marked inhibition of cell growth and clonogenic formation. The tumor-suppressive effect of KLF4 was associated with its role in up-regulating p21 and down-regulating cyclin D1, leading to cell cycle arrest at the G1-S checkpoint. Knockdown of KLF4 promoted cell growth in immortalized human bronchial epithelial cells. The enforced expression of KLF4 gene to lung cancer cells by ex vivo transfection or adenovector-mediated gene transfer suppressed tumor growth in vivo.

Conclusions: Our results suggest that KLF4 plays an important role in suppressing the growth of lung carcinoma. (Clin Cancer Res 2009;15(18):5688–95)
Decreased Poly(ADP-Ribosyl)ation of CTCF, a Transcription Factor, Is Associated with Breast Cancer Phenotype and Cell Proliferation
Authors: Docquier France , Kita Georgia-Xanthi , Farrar Dawn , Jat Parmjit , O'Hare Michael , Chernukhin Igor , Gretton Svetlana , Mandal Adhip , Alldridge Louise , Klenova Elena
Published: September 2009

Purpose: There is compelling evidence of a relationship between poly(ADP-ribosyl)ation and tumorigenesis; however, much less is known about the role of specific targets of poly(ADP-ribosyl)ation in tumor development. Two forms of the multifunctional transcription factor, CTCF, were previously identified: a 130-kDa protein (CTCF-130), characteristic for cell lines, and a 180-kDa protein (CTCF-180), modified by poly(ADP-ribosyl)ation. This study was aimed to investigate differential poly(ADP-ribosyl)ation of CTCF in normal and tumor breast tissues.

Experimental Design: Western blot analysis, mass spectrometry, and immunohistochemical and immunofluorescent stainings were used to characterize CTCF-130 and CTCF-180 in breast cell lines, primary cultures, and normal and tumor breast tissues. The immunoreactivity score was used for CTCF-130 quantification in tissues.

Results: We discovered that only CTCF-180 is detected in the normal breast tissues, whereas both CTCF-130 and CTCF-180 are present in breast tumors. Using an antibody specific for CTCF-130, we observed that 87.7% of breast tumors were positive for CTCF-130. A negative correlation existed between the levels of CTCF-130, tumor stage, and tumor size. Significantly, a transition from CTCF-180 to CTCF-130 was discovered in primary cultures generated from normal breast tissues, indicating a link between CTCF-130 and proliferation. Conversely, the appearance of CTCF-180 was observed following growth arrest in breast cell lines.

Conclusions: Collectively, our data suggest that the loss of CTCF poly(ADP-ribosyl)ation is associated with cell proliferation and breast tumor development. We propose the use of CTCF-130 as a marker for tumor breast cells and lower levels of CTCF-130 as an indicator of unfavorable prognosis. (Clin Cancer Res 2009;15(18):5762–71)
High-Dose Zoledronic Acid Impacts Bone Remodeling with Effects on Osteoblastic Lineage and Bone Mechanical Properties
Authors: Pozzi Samantha , Vallet Sonia , Mukherjee Siddhartha , Cirstea Diana , Vaghela Nileshwari , Santo Loredana , Rosen Eyal , Ikeda Hiroshi , Okawa Yutaka , Kiziltepe Tanyel , Schoonmaker Jesse , Xie Wanling , Hideshima Teru , Weller Edie , Bouxsein Mary L. , Munshi Nikhil C. , Anderson Kenneth C. , Raje Noopur
Published: September 2009

Purpose: The increasing incidence of osteonecrosis of the jaw and its possible association with high cumulative doses of bisphosphonate led us to study the effects of high doses of zoledronic acid (ZA) on bone remodeling.

Experimental Design: Five-week-old C57BL6 mice were treated with saline or ZA weekly for 3 weeks at increasing doses (0.05-1 mg/Kg). Effects of ZA on bone remodeling were studied using standard assays.

Results: We observed an increase in bone mineral density and content in treated animals at doses of 0.05 mg/Kg, which was not further enhanced at higher doses of ZA. Trabecular bone volume at the proximal tibia and the distal femur assessed by histomorphometry and microCT, respectively, increased significantly in ZA-treated groups. There was however no difference between 0.5 and 1 mg/kg, suggesting a ceiling effect for ZA. ZA led to decreased numbers of osteoclasts and osteoblasts per bone perimeter that paralleled a significant reduction of serum levels of TRAC5b and osteocalcin in vivo. Effects on osteoblasts were confirmed in in vitro assays. Mechanical testing of the femur showed increased brittleness in ZA-treated mice.

Conclusions: High doses of ZA inhibit both osteoclast and osteoblasts function and bone remodeling in vivo interfering with bone mechanical properties. No dose response was noted beyond 0.5 mg/kg suggesting that lower doses of ZA may be adequate in inhibiting bone resorption. Our data may help inform future studies of ZA use with respect to alternate and lower doses in the treatment of patients with cancer bone disease. (Clin Cancer Res 2009;15(18):5829–39)
Identification of the Transcription Factor Single-Minded Homologue 2 as a Potential Biomarker and Immunotherapy Target in Prostate Cancer
Authors: Arredouani Mohamed S. , Lu Bin , Bhasin Manoj , Eljanne Miriam , Yue Wen , Mosquera Juan-Miguel , Bubley Glenn J. , Li Vivian , Rubin Mark A. , Libermann Towia A. , Sanda Martin G.
Published: September 2009

Purpose: Identification of novel biomarkers and immunotherapy targets for prostate cancer (PCa) is crucial to better diagnosis and therapy. We sought to identify novel PCa tumor-associated antigens (TAA) that are expressed in PCa, absent in nonprostate human tissue, and immunogenic for immune responses restricted by human HLA.

Experimental Design and Results: Using microarray analysis of normal and cancerous human prostate tissues, we identified 1,063 genes overexpressed in PCa. After validating 195 transcripts in publicly available array data sets, we interrogated expression of these TAAs in normal human tissues to identify genes that are not expressed at detectable levels in normal, nonprostate adult human tissue. We identified 23 PCa TAA candidates. Real-time PCR confirmed that 15 of these genes were overexpressed in PCa (P< 0.05 for each). The most frequently overexpressed gene, single-minded homologue 2 (SIM2), was selected for further evaluation as a potential target for immunotherapy. ELISA assay revealed that a fraction of PCa patients exhibited immune responsiveness to SIM2 as evidenced by the presence of autoantibodies to SIM2 in their sera. We next showed binding of putative HLA-A2.1–restricted SIM2 epitopes to human A2.1, and immunization of transgenic HLA-A2.1 mice showed induction of SIM2-specific CTL responses in vivo.

Conclusions: Our findings that SIM2 is selectively expressed in PCa, that human HLA-A2.1–restricted SIM2 epitopes induce specific T cells in vivo, and that anti-SIM2 antibodies are detectable in PCa patients' sera implicate SIM2 as a PCa-associated antigen that is a suitable potential target for PCa immunotherapy. (Clin Cancer Res 2009;15(18):5794–802)
Prevention of Progression in Monoclonal Gammopathy of Undetermined Significance
Authors: Rajkumar S. Vincent
Published: September 2009

Monoclonal gammopathy of undetermined significance (MGUS) is a common premalignant plasma cell proliferative disorder with a lifelong risk of progression to multiple myeloma. Because myeloma is an incurable malignancy, strategies to delay or prevent progression in high-risk patients are of considerable importance. (Clin Cancer Res 2009;15(18):5606–8)
Suberoylanilide hydroxamic acid sensitizes human oral cancer cells to TRAIL-induced apoptosis through increase DR5 expression
Authors: Yeh Cheng-Chang , Deng Yi-Ting , Sha De-Yuan , Hsiao Michael , Kuo Mark Yen-Ping
Published: September 2009

Suberoylanilide hydroxamic acid has been shown to selectively induce tumor apoptosis in cell cultures and animal models in several types of cancers and is about as a promising new class of chemotherapeutic agents. In addition, suberoylanilide hydroxamic acid showed synergistic anticancer activity with radiation, cisplatin, and tumor necrosis factor–related apoptosis–inducing ligand (TRAIL) in some cancers. Here, we report suberoylanilide hydroxamic acid also induced apoptosis in human oral cancer cells. Western blotting showed suberoylanilide hydroxamic acid increased Fas, Fas ligand, DR4, and DR5 protein expression and activated caspase-8 and caspase-9. The apoptosis was almost completely inhibited by caspase-8 inhibitor Z-IETD-FMK and attenuated by caspase-9 inhibitor Z-LEHD-FMK. Human recombinant DR5/Fc chimera protein but not Fas/Fc or DR4/Fc significantly inhibited apoptosis induced by suberoylanilide hydroxamic acid. These results suggest that suberoylanilide hydroxamic acid induces apoptosis mainly through activation of DR5/TRAIL death pathway. Furthermore, subtoxic concentrations of suberoylanilide hydroxamic acid sensitize two TRAIL resistant human oral cancer cells, SAS and Ca9-22, to exogenous recombinant TRAIL-induced apoptosis in a p53-independent manner. Combined treatment of suberoylanilide hydroxamic acid and TRAIL may be used as a new promising therapy for oral cancer. [Mol Cancer Ther 2009;8(9):2718–25]
Prx1 Enhances Androgen Receptor Function in Prostate Cancer Cells by Increasing Receptor Affinity to Dihydrotestosterone
Authors: Chhipa Rishi Raj , Lee Kwang-Soon , Onate Sergio , Wu Yue , Ip Clement
Published: September 2009

Androgen receptor (AR) signaling plays a critical role in the development and progression of prostate cancer. It has been reported previously that peroxiredoxin-1 (Prx1), a member of a novel family of peroxidases, interacts physically with AR to enhance AR transactivation of target genes. In the present study, we evaluated the biological significance of Prx1 in modulating dihydrotestosterone (DHT)-stimulated growth and AR target gene expression of prostate cancer cells. We also investigated the mechanism by which Prx1 might potentiate AR signaling. The contribution of Prx1 was assessed mainly by using the approach of stable Prx1 knockdown. The major observations are as follows: (a) A low level of Prx1 desensitizes cells to growth stimulation and AR target gene induction by DHT, such that exposure to a higher level of DHT is required to reach the same magnitude of response when Prx1 is depressed; (b) Prx1 increases the affinity of AR to DHT and decreases the rate of DHT dissociation from the occupied receptor; (c) Prx1 enhances the NH2 terminus and COOH terminus interaction of AR; a stronger N-C interaction is consistent with a more robust AR activation signal by keeping DHT tight in the ligand-binding pocket; (d) the stimulatory effects of Prx1 on AR ligand binding affinity and AR N-C interaction are manifested regardless of a wild-type or mutant AR. The above findings led us to believe that Prx1 may be a therapeutic target in blocking the transition of prostate cancer from an androgen-dependent to an androgen-refractory phenotype. (Mol Cancer Res 2009;7(9):1543–52)
Prevalence and Functional Analysis of Sequence Variants in the ATR Checkpoint Mediator Claspin
Authors: Zhang Jianmin , Song Young-Han , Brannigan Brian W. , Wahrer Doke C.R. , Schiripo Taryn A. , Harris Patricia L. , Haserlat Sara M. , Ulkus Lindsey E. , Shannon Kristen M. , Garber Judy E. , Freedman Matthew L. , Henderson Brian E. , Zou Lee , Sgroi Dennis C. , Haber Daniel A. , Bell Daphne W.
Published: September 2009

Mutational inactivation of genes controlling the DNA-damage response contributes to cancer susceptibility within families and within the general population as well as to sporadic tumorigenesis. Claspin (CLSPN) encodes a recently recognized mediator protein essential for the ATR and CHK1-dependent checkpoint elicited by replicative stress or the presence of ssDNA. Here, we describe a study to determine whether mutational disruption of CLSPN contributes to cancer susceptibility and sporadic tumorigenesis. We resequenced CLSPN from the germline of selected cancer families with a history of breast cancer (n = 25) or a multicancer phenotype (n = 46) as well as from a panel of sporadic cancer cell lines (n = 52) derived from a variety of tumor types. Eight nonsynonymous variants, including a recurrent mutation, were identified from the germline of two cancer-prone individuals and five cancer cell lines of breast, ovarian, and hematopoietic origin. None of the variants was present within population controls. In contrast, mutations were rare within genes encoding the CLSPN-interacting protein ATR and its binding partner ATRIP. One variant of CLSPN, encoding the I783S missense mutation, was defective in its ability to mediate CHK1 phosphorylation following DNA damage and was unable to rescue sensitivity to replicative stress in CLSPN-depleted cells. Taken together, these observations raise the possibility that CLSPN may encode a component of the DNA-damage response pathway that is targeted by mutations in human cancers, suggesting the need for larger population-based studies to investigate whether CLSPN variants contribute to cancer susceptibility. (Mol Cancer Res 2009;7(9):1510–16)
Functional Analysis of Secreted Caveolin-1 in Mouse Models of Prostate Cancer Progression
Authors: Watanabe Masami , Yang Guang , Cao Guangwen , Tahir Salahaldin A. , Naruishi Koji , Tabata Ken-ichi , Fattah Elmoataz Abdel , Rajagopalan Kartik , Timme Terry L. , Park Sanghee , Kurosaka Shinji , Edamura Kohei , Tanimoto Ryuta , Demayo Francesco J. , Goltsov Alexei A. , Thompson Timothy C.
Published: September 2009

Previously, we reported that caveolin-1 (cav-1) is overexpressed in metastatic prostate cancer and that virulent prostate cancer cells secrete biologically active cav-1. We also showed that cav-1 expression leads to prosurvival activities through maintenance of activated Akt and that cav-1 is taken up by other cav-1–negative tumor cells and/or endothelial cells, leading to stimulation of angiogenic activities through PI-3-K-Akt-eNOS signaling. To analyze the functional consequences of cav-1 overexpression on the development and progression of prostate cancer in vivo, we generated PBcav-1 transgenic mice. Adult male PBcav-1 mice showed significantly increased prostatic wet weight and higher incidence of epithelial hyperplasia compared with nontransgenic littermates. Increased immunostaining for cav-1, proliferative cell nuclear antigen, P-Akt, and reduced nuclear p27Kip1 staining occurred in PBcav-1 hyperplastic prostatic lesions. PBcav-1 mice showed increased resistance to castration-induced prostatic regression and elevated serum cav-1 levels compared with nontransgenic littermates. Intraprostatic injection of androgen-sensitive, cav-1–secreting RM-9 mouse prostate cancer cells resulted in tumors that were larger in PBcav-1 mice than in nontransgenic littermates (P = 0.04). Tail vein inoculation of RM-9 cells produced significantly more experimental lung metastases in PBcav-1 males than in nontransgenic male littermates (P = 0.001), and in cav-1+/+ mice than in cav-1−/− mice (P = 0.041). Combination treatment with surgical castration and systemic cav-1 antibody dramatically reduced the number of experimental metastases. These experimental data suggest a causal association of secreted cav-1 and prostate cancer growth and progression. (Mol Cancer Res 2009;7(9):1446–55)