bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscerosomatic interaction induced by myocardial ischemia in conscious dogs
Authors: Gwirtz Patricia A. , Dickey Jerry , Vick David , Williams Maurice A. , Foresman Brian
Published: May 2007

Studies tested the hypothesis that myocardial ischemia induces increased paraspinal muscular tone localized to the T2–T5region that can be detected by palpatory means. This is consistent with theories of manual medicine suggesting that disturbances in visceral organ physiology can cause increases in skeletal muscle tone in specific muscle groups. Clinical studies in manual and traditional medicine suggest this phenomenon occurs during episodes of myocardial ischemia and may have diagnostic potential. However, there is little direct evidence of a cardiac-somatic mechanism to explain these findings. Chronically instrumented dogs [12 neurally intact and 3 following selective left ventricular (LV) sympathectomy] were examined before, during, and after myocardial ischemia. Circumflex blood flow (CBF), left ventricular contractile function, electromyographic (EMG) analysis, and blinded manual palpatory assessments (MPA) of tissue over the transverse spinal processes at segments T2–T5and T11–T12(control) were performed. Myocardial ischemia was associated with a decrease in myocardial contractile function and an increase in heart rate. MPA revealed increases in muscle tension and texture/firmness during ischemia in the T2–T5segments on the left, but not on the right or in control segments. EMG demonstrated increased amplitude for the T4–T5segments. After LV sympathectomy, MPA and EMG evidence of increased muscle tone were absent. In conclusion, myocardial ischemia is associated with significant increased paraspinal muscle tone localized to the left side T4–T5myotomes in neurally intact dogs. LV sympathectomy eliminates the somatic response, suggesting that sympathetic neural traffic between the heart and somatic musculature may function as the mechanism for the interaction.
Effects of exercise training on quadriceps muscle gene expression in chronic obstructive pulmonary disease
Authors: Radom-Aizik Shlomit , Kaminski Naftali , Hayek Shlomo , Halkin Hillel , Cooper Dan M. , Ben-Dov Issahar
Published: May 2007

Exercise capacity and training response are limited in chronic obstructive pulmonary disease (COPD), but the extent to which this is related to altered skeletal muscle function is not fully understood. To test the hypothesis that muscle gene expression is altered in COPD, we performed needle biopsies from the vastus lateralis of six COPD patients and five sedentary age-matched healthy men, before and after 3 mo of exercise training. RNA was hybridized to Affymetrix U133A Genechip arrays. In addition, peak O2 uptake and other functional parameters (e.g., 6-min walk) were measured before and after training. The 6-min walk test increased significantly following training in both groups (53.6 ± 18.6 m in controls, P = 0.045; 37.1 ± 6.7 m in COPD, P = 0.002), but peak O2 uptake increased only in controls (19.4 ± 4.5%, P = 0.011). Training significantly altered muscle gene expression in both groups, but the number of affected genes was lower in the COPD patients (231) compared with controls (573). Genes related to energy pathways had higher expression in trained controls. In contrast, oxidative stress, ubiquitin proteasome, and COX gene pathways had higher expression in trained COPD patients, and some genes (e.g., COX11, COX15, and MAPK-9) were upregulated by training only in COPD patients. We conclude that both COPD and control subjects demonstrated functional responses to training but with somewhat different patterns in muscle gene expression. The pathways that are uniquely induced by exercise in COPD (e.g., ubiquitin proteasome and COX) might indicate a greater degree of tissue stress (perhaps by altered O2 and CO2 dynamics) than in controls.
Dormant Tumor Cells Develop Cross-Resistance to Apoptosis Induced by CTLs or Imatinib Mesylate via Methylation of Suppressor of Cytokine Signaling 1
Authors: Saudemont Aurore , Hamrouni Abdelbasset , Marchetti Philippe , Liu Jizhong , Jouy Nathalie , Hetuin Dominique , Colucci Francesco , Quesnel Bruno
Published: May 2007

In the BCR/ABL DA1-3b mouse model of acute myelogenous leukemia, dormant tumor cells may persist in the host in a state of equilibrium with the CD8+ CTL-mediated immune response by actively inhibiting T cells. Dormant tumor cells also show a progressive decrease of suppressor of cytokine signaling 1 (SOCS1) gene expression and a deregulation of the Janus-activated kinase/signal transducers and activators of transcription (JAK/STAT) pathway due to methylation of the SOCS1 gene. Dormant tumor cells were more resistant to apoptosis induced by specific CTLs, but resistance decreased when SOCS1 expression was restored via demethylation or gene transfer. AG490 JAK2 inhibitor decreased the resistance of dormant tumor cells to CTLs, but MG132 proteasome inhibitor was effective only in SOCS1-transfected cells. Thus, SOCS1 regulation of the JAK/STAT pathways contributes to the resistance of tumor cells to CTL-mediated killing. Resistance of dormant tumor cells to apoptosis was also observed when induced by irradiation, cytarabine, or imatinib mesylate, but was reduced by SOCS1 gene transfer. This cross-resistance to apoptosis was induced by interleukin 3 (IL-3) overproduction by dormant tumor cells and was reversed with an anti–IL-3 antibody. Thus, tumor cells that remain dormant for long periods in the host in spite of a specific CTL immune response may deregulate their JAK/STAT pathways and develop cross-resistance to various treatments through an IL-3 autocrine loop. These data suggest possible new therapeutic targets to eradicate dormant tumor cells. [Cancer Res 2007;67(9):4491–8]
Modeling Breast Cancer–Associated c-Src and EGFR Overexpression in Human MECs: c-Src and EGFR Cooperatively Promote Aberrant Three-dimensional Acinar Structure and Invasive Behavior
Authors: Dimri Manjari , Naramura Mayumi , Duan Lei , Chen Jing , Ortega-Cava Cesar , Chen Gengsheng , Goswami Rasna , Fernandes Norvin , Gao Qingshen , Dimri Goberdhan P. , Band Vimla , Band Hamid
Published: May 2007

Epidermal growth factor receptor (EGFR), a member of the ErbB family of receptor tyrosine kinases, is overexpressed in as many as 60% cases of breast and other cancers. EGFR overexpression is a characteristic of highly aggressive molecular subtypes of breast cancer with basal-like and BRCA1 mutant phenotypes distinct from ErbB2-overexpressing breast cancers. Yet, EGFR is substantially weaker compared with ErbB2 in promoting the oncogenic transformation of nontumorigenic human mammary epithelial cells (human MEC), suggesting a role for cooperating oncogenes. Here, we have modeled the co-overexpression of EGFR and a biologically and clinically relevant potential modifier c-Src in two distinct immortal but nontumorigenic human MECs. Using a combination of morphologic analysis and confocal imaging of polarity markers in three-dimensional Matrigel culture together with functional analyses of early oncogenic traits, we show for the first time that EGFR and c-Src co-overexpression but not EGFR or c-Src overexpression alone unleashes an oncogenic signaling program that leads to hyperproliferation and loss of polarity in three-dimensional acinar cultures, marked enhancement of migratory and invasive behavior, and anchorage-independent growth. Our results establish that EGFR overexpression in an appropriate context (modeled here using c-Src overexpression) can initiate oncogenic transformation of nontumorigenic human MECs and provide a suitable in vitro model to interrogate human breast cancer–relevant oncogenic signaling pathways initiated by overexpressed EGFR and to identify modifiers of EGFR-mediated breast oncogenesis. [Cancer Res 2007;67(9):4164–72]
Mitogen-Activated Protein Kinase Phosphatase-1 Is a Mediator of Breast Cancer Chemoresistance
Authors: Small George W. , Shi Yue Y. , Higgins Linda S. , Orlowski Robert Z.
Published: May 2007

The mitogen-activated protein kinase (MAPK) phosphatase (MKP)-1 is overexpressed in a large proportion of breast cancers, and in some systems interferes with chemotherapy-mediated proapoptotic signaling through c-Jun-NH2-terminal kinase (JNK). We therefore sought to examine whether MKP-1 is a mediator of breast cancer chemoresistance using A1N4-myc human mammary epithelial cells, and BT-474 and MDA-MB-231 breast carcinoma cells. Transient or stable overexpression of MKP-1 reduced caspase activation and DNA fragmentation while enhancing viability in the face of treatment with alkylating agents (mechlorethamine), anthracylines (doxorubicin), and microtubule inhibitors (paclitaxel). This overexpression was associated with suppression of JNK activation, and JNK blockade alone induced similar effects. In contrast, reduction of MKP-1 levels using a small interfering RNA, or its targeted inactivation, enhanced sensitivity to these drugs, and this was associated with increased JNK activity. Pharmacologic reduction of MKP-1 by pretreatment with a novel p38 MAPK inhibitor, SD-282, suppressed MKP-1 activation by mechlorethamine, enhanced active JNK levels, and increased alkylating agent–mediated apoptosis. Combination treatment with doxorubicin and mechlorethamine had similar effects, and the enhanced efficacy of this regimen was abolished by forced overexpression of MKP-1. These results suggest that the clinical efficacy of combinations of alkylating agents and anthracyclines are due to the ability of the latter to target MKP-1. Moreover, they support the hypothesis that MKP-1 is a significant mediator of breast cancer chemoresistance, and provide a rationale for development and translation of other agents targeting MKP-1 into the clinical arena to overcome resistance and induce chemosensitization. [Cancer Res 2007;67(9):4459–66]
Identification of Epigenetically Silenced Genes in Tumor Endothelial Cells
Authors: Hellebrekers Debby M.E.I. , Melotte Veerle , Viré Emmanuelle , Langenkamp Elise , Molema Grietje , Fuks François , Herman James G. , Van Criekinge Wim , Griffioen Arjan W. , van Engeland Manon
Published: May 2007

Tumor angiogenesis requires intricate regulation of gene expression in endothelial cells. We recently showed that DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors directly repress endothelial cell growth and tumor angiogenesis, suggesting that epigenetic modifications mediated by DNMTs and HDAC are involved in regulation of endothelial cell gene expression during tumor angiogenesis. To understand the mechanisms behind the epigenetic regulation of tumor angiogenesis, we used microarray analysis to perform a comprehensive screen to identify genes down-regulated in tumor-conditioned versus quiescent endothelial cells, and reexpressed by 5-aza-2′-deoxycytidine (DAC) and trichostatin A (TSA). Among the 81 genes identified, 77% harbored a promoter CpG island. Validation of mRNA levels of a subset of genes confirmed significant down-regulation in tumor-conditioned endothelial cells and reactivation by treatment with a combination of DAC and TSA, as well as by both compounds separately. Silencing of these genes in tumor-conditioned endothelial cells correlated with promoter histone H3 deacetylation and loss of H3 lysine 4 methylation, but did not involve DNA methylation of promoter CpG islands. For six genes, down-regulation in microdissected human tumor endothelium was confirmed. Functional validation by RNA interference revealed that clusterin, fibrillin 1, and quiescin Q6 are negative regulators of endothelial cell growth and angiogenesis. In summary, our data identify novel angiogenesis-suppressing genes that become silenced in tumor-conditioned endothelial cells in association with promoter histone modifications and reactivated by DNMT and HDAC inhibitors through reversal of these epigenetic modifications, providing a mechanism for epigenetic regulation of tumor angiogenesis. [Cancer Res 2007;67(9):4138–48]
CD34 Expression by Hair Follicle Stem Cells Is Required for Skin Tumor Development in Mice
Authors: Trempus Carol S. , Morris Rebecca J. , Ehinger Matthew , Elmore Amy , Bortner Carl D. , Ito Mayumi , Cotsarelis George , Nijhof Joanne G.W. , Peckham John , Flagler Norris , Kissling Grace , Humble Margaret M. , King Leon C. , Adams Linda D. , Desai Dhimant , Amin Shantu , Tennant Raymond W.
Published: May 2007

The cell surface marker CD34 marks mouse hair follicle bulge cells, which have attributes of stem cells, including quiescence and multipotency. Using a CD34 knockout (KO) mouse, we tested the hypothesis that CD34 may participate in tumor development in mice because hair follicle stem cells are thought to be a major target of carcinogens in the two-stage model of mouse skin carcinogenesis. Following initiation with 200 nmol 7,12-dimethylbenz(a)anthracene (DMBA), mice were promoted with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 20 weeks. Under these conditions, CD34KO mice failed to develop papillomas. Increasing the initiating dose of DMBA to 400 nmol resulted in tumor development in the CD34KO mice, albeit with an increased latency and lower tumor yield compared with the wild-type (WT) strain. DNA adduct analysis of keratinocytes from DMBA-initiated CD34KO mice revealed that DMBA was metabolically activated into carcinogenic diol epoxides at both 200 and 400 nmol. Chronic exposure to TPA revealed that CD34KO skin developed and sustained epidermal hyperplasia. However, CD34KO hair follicles typically remained in telogen rather than transitioning into anagen growth, confirmed by retention of bromodeoxyuridine-labeled bulge stem cells within the hair follicle. Unique localization of the hair follicle progenitor cell marker MTS24 was found in interfollicular basal cells in TPA-treated WT mice, whereas staining remained restricted to the hair follicles of CD34KO mice, suggesting that progenitor cells migrate into epidermis differently between strains. These data show that CD34 is required for TPA-induced hair follicle stem cell activation and tumor formation in mice. [Cancer Res 2007;67(9):4173–81]
Breast Tumor Kinase (Protein Tyrosine Kinase 6) Regulates Heregulin-Induced Activation of ERK5 and p38 MAP Kinases in Breast Cancer Cells
Authors: Ostrander Julie Hanson , Daniel Andrea R. , Lofgren Kristopher , Kleer Celina G. , Lange Carol A.
Published: May 2007

Total tyrosine kinase activity is often elevated in both cytosolic and membrane fractions of malignant breast tissue and correlates with a decrease in disease-free survival. Breast tumor kinase (Brk; protein tyrosine kinase 6) is a soluble tyrosine kinase that was cloned from a metastatic breast tumor and found to be overexpressed in a majority of breast tumors. Herein, we show that Brk is overexpressed in 86% of invasive ductal breast tumors and coexpressed with ErbB family members in breast cancer cell lines. Additionally, the ErbB ligand, heregulin, activates Brk kinase activity. Knockdown of Brk by stable expression of short hairpin RNA (shRNA) in T47D breast cancer cells decreases proliferation and blocks epidermal growth factor (EGF)- and heregulin-induced activation of Rac GTPase, extracellular signal-regulated kinase (ERK) 5, and p38 mitogen-activated protein kinase (MAPK) but not Akt, ERK1/2, or c-Jun NH2-terminal kinase. Furthermore, EGF- and heregulin-induced cyclin D1 expression is dependent on p38 signaling and inhibited by Brk shRNA knockdown. The myocyte enhancer factor 2 transcription factor target of p38 MAPK and ERK5 signaling is also sensitive to altered Brk expression. Finally, heregulin-induced migration of T47D cells requires p38 MAPK activity and is blocked by Brk knockdown. These results place Brk in a novel signaling pathway downstream of ErbB receptors and upstream of Rac, p38 MAPK, and ERK5 and establish the ErbB-Brk-Rac-p38 MAPK pathway as a critical mediator of breast cancer cell migration. [Cancer Res 2007;67(9):4199–209]
Carcinogen-Specific Gene Expression Profiles in Short-term Treated Eker and Wild-type Rats Indicative of Pathways Involved in Renal Tumorigenesis
Authors: Stemmer Kerstin , Ellinger-Ziegelbauer Heidrun , Ahr Hans-Juergen , Dietrich Daniel R.
Published: May 2007

Eker rats heterozygous for a dominant germline mutation in the tuberous sclerosis 2 (Tsc2) tumor suppressor gene were used as a model to study renal carcinogenesis. Eker and corresponding wild-type rats were exposed to genotoxic aristolochic acid (AA) or non-genotoxic ochratoxin A (OTA) to elucidate early carcinogen-specific gene expression changes and to test whether Eker rats are more sensitive to carcinogen-induced changes in gene expression. Male Eker and wild-type rats were gavaged daily with AA (10 mg/kg body weight) or OTA (210 μg/kg body weight). After 1, 3, 7, and 14 days of exposure, renal histopathology, tubular cell proliferation, and Affymetrix gene expression profiles from renal cortex/outer medulla were analyzed. AA-treated Eker and wild-type rats were qualitatively comparable in all variables assessed, suggesting a Tsc2-independent mechanism of action. OTA treatment resulted in slightly increased cortical pathology and significantly elevated cell proliferation in both strains, although Eker rats were more sensitive. Deregulated genes involved in the phosphatidylinositol 3-kinase-AKT-Tsc2-mammalian target of rapamycin signaling, among other important genes prominent in tumorigenesis, in conjunction with the enhanced cell proliferation and presence of preneoplastic lesions suggested involvement of Tsc2 in OTA-mediated toxicity and carcinogenicity, especially as deregulation of genes involved in this pathway was more prominent in the Tsc2 mutant Eker rat. [Cancer Res 2007;67(9):4052–68]
15(S)-Hydroxyeicosatetraenoic Acid–Induced Angiogenesis Requires STAT3-Dependent Expression of VEGF
Authors: Srivastava Kalyan , Kundumani-Sridharan Venkatesh , Zhang Baolin , Bajpai Arun K. , Rao Gadiparthi N.
Published: May 2007

15(S)-Hydroxyeicosatetraenoic acid [15(S)-HETE] activated signal transducer and activator of transcription 3 (STAT3) as measured by its tyrosine phosphorylation, translocation from the cytoplasm to the nucleus, DNA binding, and reporter gene activity in human dermal microvascular endothelial cells (HDMVEC). Inhibition of STAT3 activation via adenovirus-mediated expression of its dominant-negative mutant suppressed 15(S)-HETE–induced HDMVEC migration and tube formation in vitro and aortic ring and Matrigel plug angiogenesis in vivo. 15(S)-HETE induced the expression of vascular endothelial growth factor (VEGF) in a time- and STAT3-dependent manner in HDMVEC. In addition, neutralizing anti-VEGF antibodies blocked 15(S)-HETE–induced HDMVEC migration and tube formation in vitro and aortic ring and Matrigel plug angiogenesis in vivo. Together, these results show for the first time that 15(S)-HETE–induced angiogenesis requires STAT3-dependent expression of VEGF. In view of these findings, it is suggested that eicosanoids, particularly 15(S)-HETE, via its capacity to stimulate angiogenesis, may influence the progression of cancer and vascular disease. [Cancer Res 2007;67(9):4328–36]
Mammalian Target of Rapamycin Activation Impairs Hepatocytic Differentiation and Targets Genes Moderating Lipid Homeostasis and Hepatocellular Growth
Authors: Parent Romain , Kolippakkam Deepak , Booth Garrett , Beretta Laura
Published: May 2007

The mammalian target of rapamycin (mTOR) pathway, a major regulator of translation, is frequently activated in hepatocellular carcinomas. We investigated the effects of mTOR activation in the human HepaRG cells, which possess potent hepatocytic differentiation capability. Differentiation of HepaRG cells into functional and polarized hepatocyte-like cells correlated with a decrease in mTOR and Akt activities. Stable cell lines expressing an activated mutant of mTOR were generated. Sustained activation of mTOR impaired the hepatocytic differentiation capability of these cells as shown by impaired formation of bile canaliculi, absence of polarity, and reduced secretion of α1-antitrypsin. An inhibitor of mTOR, rapamycin, was able to revert this phenotype. Furthermore, increased mTOR activity in HepaRG cells resulted in their resistance to the antiproliferative effects of transforming growth factor-β1. Profiling of polysome-bound transcripts indicated that activated mTOR specifically targeted genes posttranscriptionally regulated on hepatocytic differentiation. Three major biological networks targeted by activated mTOR were identified: (a) cell death associated with tumor necrosis factor superfamily members, IFNs and caspases; (b) lipid homeostasis associated with the transcription factors PPARα, PPARδ, and retinoid X receptor β; and (c) liver development associated with CCAAT/enhancer binding protein α and hepatic mitogens. In conclusion, increased mTOR activity conferred a preneoplastic phenotype to the HepaRG cells by altering the translation of genes vital for establishing normal hepatic energy homeostasis and moderating hepatocellular growth. [Cancer Res 2007;67(9):4337–45]
Suppressive Effects of Statins on Acute Promyelocytic Leukemia Cells
Authors: Sassano Antonella , Katsoulidis Efstratios , Antico Giovanni , Altman Jessica K. , Redig Amanda J. , Minucci Saverio , Tallman Martin S. , Platanias Leonidas C.
Published: May 2007

The family of statins includes pharmacologic inhibitors of the 3-hydroxy-3-methylglutaryl-CoA reductase that are potent regulators of cholesterol biosynthesis. In addition to their cholesterol-lowering effects, statins inhibit cell proliferation and promote apoptosis of malignant cells in vitro, but their potential therapeutic roles in the treatment of malignancies remain to be defined. We examined the effects of statins on the growth and differentiation of acute myeloid leukemia (AML) cells. Atorvastatin and fluvastatin were found to be potent inducers of cell differentiation and apoptosis of the NB4 acute promyelocytic leukemia (APL) cell line. Such effects correlated with activation of the small G-proteins Rac1/Cdc42 and downstream engagement of the c-Jun NH2-terminal kinase kinase pathway, whose function was found to be essential for the generation of proapoptotic responses. Importantly, different statins were found to enhance all-trans-retinoic acid (ATRA)–dependent differentiation of APL blasts and reverse resistance to the antileukemic effects of ATRA. In addition, fluvastatin exhibited growth-inhibitory properties on primary bone marrow–derived leukemic progenitors from patients with AML and enhanced the suppressive effects of ATRA on leukemic progenitor colony formation. Altogether, these studies establish that statins exhibit potent antileukemic properties in vitro and raise the possibility that combinations of statins with ATRA may be an effective approach to overcome the development of ATRA resistance by the leukemic cells. [Cancer Res 2007;67(9):4524–32]
A Transgenic Mouse Model of Plasma Cell Malignancy Shows Phenotypic, Cytogenetic, and Gene Expression Heterogeneity Similar to Human Multiple Myeloma
Authors: Boylan Kristin L.M. , Gosse Mary A. , Staggs Sarah E. , Janz Siegfried , Grindle Suzanne , Kansas Geoffrey S. , Van Ness Brian G.
Published: May 2007

Multiple myeloma is an incurable plasma cell malignancy for which existing animal models are limited. We have previously shown that the targeted expression of the transgenes c-Myc and Bcl-XL in murine plasma cells produces malignancy that displays features of human myeloma, such as localization of tumor cells to the bone marrow and lytic bone lesions. We have isolated and characterized in vitro cultures and adoptive transfers of tumors from Bcl-xl/Myc transgenic mice. Tumors have a plasmablastic morphology and variable expression of CD138, CD45, CD38, and CD19. Spectral karyotyping analysis of metaphase chromosomes from primary tumor cell cultures shows that the Bcl-xl/Myc tumors contain a variety of chromosomal abnormalities, including trisomies, translocations, and deletions. The most frequently aberrant chromosomes are 12 and 16. Three sites for recurring translocations were also identified on chromosomes 4D, 12F, and 16C. Gene expression profiling was used to identify differences in gene expression between tumor cells and normal plasma cells (NPC) and to cluster the tumors into two groups (tumor groups C and D), with distinct gene expression profiles. Four hundred and ninety-five genes were significantly different between both tumor groups and NPCs, whereas 124 genes were uniquely different from NPCs in tumor group C and 204 genes were uniquely different from NPCs in tumor group D. Similar to human myeloma, the cyclin D genes are differentially dysregulated in the mouse tumor groups. These data suggest the Bcl-xl/Myc tumors are similar to a subset of plasmablastic human myelomas and provide insight into the specific genes and pathways underlying the human disease. [Cancer Res 2007;67(9):4069–78]
Development of Gastric Tumors in ApcMin/+ Mice by the Activation of the β-Catenin/Tcf Signaling Pathway
Authors: Tomita Hiroyuki , Yamada Yasuhiro , Oyama Takeru , Hata Kazuya , Hirose Yoshinobu , Hara Akira , Kunisada Takahiro , Sugiyama Yasuyuki , Adachi Yosuke , Linhart Heinz , Mori Hideki
Published: May 2007

Although several lines of evidence suggest the involvement of the Wnt pathway in the development of gastric cancers, the functional significance of the pathway in gastric carcinogenesis is still poorly defined. To examine the role of the Apc/β-catenin signaling pathway in the development of gastric cancers, we investigated the gastric mucosa of the ApcMin/+ mouse, which is a murine model for familial adenomatous polyposis, carrying a germ-line mutation at codon 850 of Apc. We found that aged ApcMin/+ mice spontaneously develop multiple tumors in the stomach, which are accompanied by loss of heterozygosity of Apc. Such tumors consisted of adenomatous glands with strong nuclear accumulation of β-catenin. Even a single adenomatous gland already showed nuclear accumulation of β-catenin, suggesting that Apc/β-catenin pathway is an initiating event in gastric tumorigenesis in ApcMin/+ mice. Myc and cyclin D1 expressions, which are transcriptional targets of β-catenin/Tcf, increased in the adenomatous lesions. Furthermore, β-catenin/Tcf reporter transgenic mice with ApcMin allele showed higher levels of the transcriptional activity of β-catenin/Tcf in the gastric tumors. We also treated ApcMin/+ and wild-type mice with N-methyl-N-nitrosourea (MNU), an alkylating agent that induces adenomas and adenocarcinomas in the stomach. Consequently, MNU-treated ApcMin/+ mice significantly enhanced the tumor development in comparison with ApcMin/+ mice or MNU-treated wild-type mice. Several gastric tumors in MNU-treated ApcMin/+ mice showed invasion into the submucosal layer. These results indicate that the Apc/β-catenin pathway may play an important role in at least subset of gastric carcinomas. In addition, ApcMin/+ mice combined with MNU could be a useful short-term model to investigate multistage carcinogenesis in the stomach. [Cancer Res 2007;67(9):4079–87]
A Gynecologic Oncology Group Study of Platinum-DNA Adducts and Excision Repair Cross-Complementation Group 1 Expression in Optimal, Stage III Epithelial Ovarian Cancer Treated with Platinum-Taxane Chemotherapy
Authors: Darcy Kathleen M. , Tian Chunqiao , Reed Eddie
Published: May 2007

To determine whether platinum-DNA adducts and/or mRNA expression of the excision nuclease excision repair cross-complementation group 1 (ERCC1) from peripheral blood leukocytes (PBL) were associated with clinical outcome in women with epithelial ovarian cancer (EOC), participants that had previously untreated, optimally resected, stage III EOC were randomized to paclitaxel plus cisplatin or carboplatin. DNA and RNA were extracted from PBLs collected 20 to 28 h post–drug infusion. DNA adducts were measured by atomic absorption spectroscopy. ERCC1 expression was evaluated by reverse transcription-PCR. There were 170 cases fully evaluable for DNA adducts and ERCC1 mRNA expression. Adduct levels ranged from 0.43 to 131 fmol platinum/μg DNA in 140 samples; and adducts were not detectable in 30 samples. ERCC1 mRNA was detectable in 132 samples and undetectable in 38. ERCC1 mRNA expression in PBLs was not associated with any clinical end point measured. The presence of detectable versus undetectable adducts was associated with longer median progression-free survival (20.4 versus 15.6 months; P = 0.084) and overall survival (60.3 versus 36.3 months; P = 0.029), respectively. Unadjusted Cox regression modeling indicated a trend toward a reduced risk of disease progression [hazard ratio (HR), 0.686; 95% confidence interval (95% CI), 0.447–1.054; P = 0.086] and a statistically significant reduction in the risk of death (HR, 0.607; 95% CI, 0.385–0.958; P = 0.032) for women with detectable versus undetectable adducts. After adjusting for clinicopathologic variables, detectable adducts were not an independent predictor of progression-free survival or overall survival. The presence of platinum-DNA adducts, but not ERCC1 mRNA expression, in PBLs was associated with better survival, but was not an independent predictor of clinical outcome in optimal advanced EOC. [Cancer Res 2007;67(9):4474–81]
Regression of Lung and Colon Cancer Xenografts by Depleting or Inhibiting RLIP76 (Ral-Binding Protein 1)
Authors: Singhal Sharad S. , Singhal Jyotsana , Yadav Sushma , Dwivedi Seema , Boor Paul J. , Awasthi Yogesh C. , Awasthi Sanjay
Published: May 2007

Ral-binding protein 1 (RALBP1) is a stress-responsive and stress-protective multispecific transporter of glutathione conjugates (GS-E) and xenobiotic toxins. It is frequently overexpressed in malignant cells and plays a prominent antiapoptotic role selectively in cancer cells through its ability to control cellular concentration of proapoptotic oxidized lipid byproducts. In the absence of chemotherapy, depletion or inhibition of RALBP1 causes regression of syngeneic mouse B16 melanoma. Because RALBP1 transports anthracycline and Vinca alkaloid drugs, as well as GS-E, and because it confers resistance to these drugs, we proposed that depletion or inhibition of RALBP1 should cause regression of human solid tumors that overexpress RALBP1 and augment chemotherapy efficacy. Non–small-cell lung cancer (NSCLC) H358 and H520 and colon SW480 cell lines were used. Cytotoxic synergy between anti-RALBP1 immunoglobulin G (IgG), cis-diammine-dichloroplatinum (II) [CDDP], and vinorelbine was examined in cell culture and xenografts of NSCLC cells. Effects of RALBP1 depletion by antisense were examined in xenografts of NSCLC H358, NSCLC H520, and colon SW480 cells. RALBP1 depletion by phosphorothioate antisense was confirmed and was associated with rapid, complete, and sustained remissions in established s.c. human lung and colon xenografts. RALBP1 inhibition by anti-RALBP1 IgG was equally as effective as antisense and enhanced CDDP-vinorelbine in lung cancer xenografts. These studies show that RALBP1 is a transporter that serves as a key effector function in cancer cell survival and is a valid target for cancer therapy, and confirm that inhibitory modulation of RALBP1 transport activity at the cell surface is sufficient for antitumor effects. [Cancer Res 2007;67(9):–9] [Cancer Res 2007;67(9):4382–9]
Identification of Ras-Related Nuclear Protein, Targeting Protein for Xenopus Kinesin-like Protein 2, and Stearoyl-CoA Desaturase 1 as Promising Cancer Targets from an RNAi-Based Screen
Authors: Morgan-Lappe Susan E. , Tucker Lora A. , Huang Xiaoli , Zhang Qian , Sarthy Aparna V. , Zakula Dorothy , Vernetti Lawrence , Schurdak Mark , Wang Jieyi , Fesik Stephen W.
Published: May 2007

To identify new candidate cancer drug targets, we used RNAi as a tool to functionally evaluate genes that play a role in maintaining human tumor cell survival. We screened a small interfering RNA (siRNA) library directed against ∼3,700 individual genes to assess the ability of siRNAs to induce cell death in an in vitro cell cytotoxicity assay. We found that siRNAs specifically targeting ras-related nuclear protein (Ran), targeting protein for Xenopus kinesin-like protein 2 (TPX2), and stearoyl-CoA desaturase 1 (SCD1), significantly reduced the survival of multiple human tumor cell lines. Further target validation studies revealed that treatment with Ran and TPX2 siRNAs differentially reduced the survival of activated K-Ras–transformed cells compared with their normal isogenic counterparts in which the mutant K-Ras gene had been disrupted (DKS-8). Knockdown of Ran and TPX2 in activated mutant K-Ras cells selectively induced S-phase arrest or transient G2-M arrest phenotypes, respectively, that preceded apoptotic cell death. Given our observations that Ran and TPX2 depletion preferentially reduces the survival of activated K-Ras–transformed cells, these two proteins may serve as useful anticancer targets in tumors expressing the activated K-Ras oncogene. [Cancer Res 2007;67(9):4390–7]
A Laminin-Collagen Complex Drives Human Epidermal Carcinogenesis through Phosphoinositol-3-Kinase Activation
Authors: Waterman Elizabeth A. , Sakai Noriyasu , Nguyen Ngon T. , Horst Basil A.J. , Veitch Dallas P. , Dey Clara N. , Ortiz-Urda Susana , Khavari Paul A. , Marinkovich M. Peter
Published: May 2007

Laminin-332 (formerly laminin-5) and collagen VII are basement membrane proteins expressed at the invasive front of human squamous cell carcinoma (SCC) tumors. These proteins have protumorigenic properties, but whether laminin-332 and collagen VII promote SCC tumors by providing adhesion or other nonadhesive extracellular cues, or whether laminin-332 and collagen VII interact together in this process remains unknown. In this study, we examined the role of these molecules by a structural approach using an in vivo model of human SCC tumorigenesis. Here, we show that individual domains (VI and V-III) on the laminin-332 β3 chain provide distinct and highly divergent cell adhesion and tumor-promoting functions. We found that laminin β3 domain VI provided a critical role in the assembly of stable adhesion complexes, but this domain was not required in SCC tumors. Instead, we found that laminin β3 domain V-III played an essential role in SCC carcinogenesis/invasion through binding to collagen VII, which in turn, led to phosphoinositol-3-kinase activation and protection from apoptosis. Overexpression of constitutively active p110 phosphoinositol-3-kinase subunit was sufficient to restore invasion and tumorigenesis in transformed cells lacking laminin-332/collagen VII interaction in a manner independent of cellular adhesion. These studies show distinctive adhesive and signaling functions in individual domains of laminin-332, one which is required for normal epithelial adhesion and one which is required for SCC tumorigenesis. This uncoupling of stable adhesion from tumor progression in our studies suggests that laminin-332/collagen VII interaction promotes epidermal carcinogenesis through signaling rather than adhesion. [Cancer Res 2007;67(9):4264–70]
Regulation of Breast Cancer Response to Chemotherapy by Fibulin-1
Authors: Pupa Serenella M. , Giuffré Sarah , Castiglioni Fabio , Bertola Lorenzo , Cantú Marco , Bongarzone Italia , Baldassari Paola , Mortarini Roberta , Argraves W. Scott , Anichini Andrea , Menard Sylvie , Tagliabue Elda
Published: May 2007

Doxorubicin treatment was found to augment the expression of the extracellular matrix (ECM) protein fibulin-1 in cultured human breast cancer cell lines and in MDA-MB-361 tumors grown in athymic mice. Doxorubicin was also found to augment tumor expression of the fibulin-1–binding proteins fibronectin and laminin-1. Growth of breast cancer cell lines on Matrigel, an ECM extract containing fibulin-1 and laminin-1, resulted in lower levels of doxorubicin-induced apoptosis as compared with controls. Moreover, tumors formed by injection of athymic mice with MDA-MB-361 cells mixed with Matrigel were significantly more doxorubicin resistant and displayed lower levels of apoptosis compared with those that formed in the absence of Matrigel. Monoclonal antibodies against fibulin-1 reversed Matrigel-dependent doxorubicin resistance. Furthermore, small interfering RNA–mediated suppression of fibulin-1 expression in breast cancer cells resulted in a 10-fold increase in doxorubicin sensitivity as compared with control cells. Together, these findings point to a role for fibulin-1 in breast cancer chemoresistance. [Cancer Res 2007;67(9):4271–7]
Prostaglandin E2 Promotes Tumor Progression by Inducing Myeloid-Derived Suppressor Cells
Authors: Sinha Pratima , Clements Virginia K. , Fulton Amy M. , Ostrand-Rosenberg Suzanne
Published: May 2007

A causative relationship between chronic inflammation and cancer has been postulated for many years, and clinical observations and laboratory experiments support the hypothesis that inflammation contributes to tumor onset and progression. However, the precise mechanisms underlying the relationship are not known. We recently reported that the proinflammatory cytokine, interleukin-1β, induces the accumulation and retention of myeloid-derived suppressor cells (MDSC), which are commonly found in many patients and experimental animals with cancer and are potent suppressors of adaptive and innate immunity. This finding led us to hypothesize that inflammation leads to cancer through the induction of MDSC, which inhibit immunosurveillance and thereby allow the unchecked persistence and proliferation of premalignant and malignant cells. We now report that host MDSC have receptors for prostaglandin E2 (PGE2) and that E-prostanoid receptor agonists, including PGE2, induce the differentiation of Gr1+CD11b+ MDSC from bone marrow stem cells, whereas receptor antagonists block differentiation. BALB/c EP2 knockout mice inoculated with the spontaneously metastatic BALB/c-derived 4T1 mammary carcinoma have delayed tumor growth and reduced numbers of MDSC relative to wild-type mice, suggesting that PGE2 partially mediates MDSC induction through the EP2 receptor. Treatment of 4T1-tumor–bearing wild-type mice with the cyclooxygenase 2 inhibitor, SC58236, delays primary tumor growth and reduces MDSC accumulation, further showing that PGE2 induces MDSC and providing a therapeutic approach for reducing this tumor-promoting cell population. [Cancer Res 2007;67(9):4507–13]
Divergent Mechanisms of Glucocorticoid Resistance in Experimental Models of Pediatric Acute Lymphoblastic Leukemia
Authors: Bachmann Petra S. , Gorman Rosemary , Papa Rachael A. , Bardell Jane E. , Ford Jette , Kees Ursula R. , Marshall Glenn M. , Lock Richard B.
Published: May 2007

Cell line models of glucocorticoid resistance in childhood acute lymphoblastic leukemia (ALL) almost invariably exhibit altered glucocorticoid receptor (GR) function. However, these findings are incongruous with those using specimens derived directly from leukemia patients, in which GR alterations are rarely found. Consequently, mechanisms of glucocorticoid resistance in the clinical setting remain largely unresolved. We present a novel paradigm of glucocorticoid resistance in childhood ALL, in which patient biopsies have been directly established as continuous xenografts in immune-deficient mice, without prior in vitro culture. We show that the GRs from six highly dexamethasone-resistant xenografts (in vitro IC50 >10 μmol/L) exhibit no defects in ligand-induced nuclear translocation and binding to a consensus glucocorticoid response element (GRE). This finding contrasts with five commonly used leukemia cell lines, all of which exhibited defective GRE binding. Moreover, whereas the GRs of dexamethasone-resistant xenografts were transcriptionally active, as assessed by the ability to induce the glucocorticoid-induced leucine zipper (GILZ) gene, resistance was associated with failure to induce the bim gene, which encodes a proapoptotic BH3-only protein. Furthermore, the receptor tyrosine kinase inhibitor, SU11657, completely reversed dexamethasone resistance in a xenograft expressing functional GR, indicating that pharmacologic reversal of glucocorticoid resistance in childhood ALL is achievable. [Cancer Res 2007;67(9):4482–90]
Relaxin-Expressing, Fiber Chimeric Oncolytic Adenovirus Prolongs Survival of Tumor-Bearing Mice
Authors: Ganesh Shanthi , Gonzalez Edick Melissa , Idamakanti Neeraja , Abramova Marina , VanRoey Melinda , Robinson Michael , Yun Chae-Ok , Jooss Karin
Published: May 2007

Selective replication of oncolytic viruses in tumor cells provides a promising approach for the treatment of human cancers. One of the limitations observed with oncolytic viruses currently used in the treatment of solid tumors is the inefficient spread of virus throughout the tumor mass following intratumoral injection. Data are presented showing that oncolytic adenoviruses expressing the relaxin gene and containing an Ad5/Ad35 chimeric fiber showed significantly enhanced transduction and increased virus spread throughout the tumor when compared with non–relaxin-expressing, Ad5-based viruses. The increased spread of such viruses throughout tumors correlated well with improved antitumor efficacy and overall survival in two highly metastatic tumor models. Furthermore, nonreplicating viruses expressing relaxin did not increase metastases, suggesting that high level expression of relaxin will not enhance metastatic spread of tumors. In summary, the data show that relaxin may play a role in rearranging matrix components within tumors, which helps recombinant oncolytic adenoviruses to spread effectively throughout the tumor mass and thereby increase the extent of viral replication within the tumor. Expressing relaxin from Ad5/Ad35 fiber chimeric adenoviruses may prove a potent and novel approach to treating patients with cancer. [Cancer Res 2007;67(9):4399–406]
The Akt/Mammalian Target of Rapamycin Signal Transduction Pathway Is Activated in High-Risk Myelodysplastic Syndromes and Influences Cell Survival and Proliferation
Authors: Follo Matilde Y. , Mongiorgi Sara , Bosi Costanza , Cappellini Alessandra , Finelli Carlo , Chiarini Francesca , Papa Veronica , Libra Massimo , Martinelli Giovanni , Cocco Lucio , Martelli Alberto M.
Published: May 2007

The Akt/mammalian target of rapamycin (mTOR) signaling pathway is important for both cell growth and survival. In particular, an impaired regulation of the Akt/mTOR axis has been strongly implicated in mechanisms related to neoplastic transformation, through enhancement of cell proliferation and survival. Myelodysplastic syndromes (MDS) are a group of heterogeneous hematopoietic stem cell disorders characterized by ineffective hematopoiesis and by a high risk of evolution into acute myelogenous leukemia (AML). The pathogenesis of the MDS evolution into AML is still unclear, although some recent studies indicate that aberrant activation of survival signaling pathways could be involved. In this investigation, done by means of immunofluorescent staining, we report an activation of the Akt/mTOR pathway in high-risk MDS patients. Interestingly, not only mTOR was activated but also its downstream targets, 4E-binding protein 1 and p70 ribosomal S6 kinase. Treatment with the selective mTOR inhibitor, rapamycin, significantly increased apoptotic cell death of CD33+ (but not CD33−) cells from high-risk MDS patients. Rapamycin was ineffective in cells from healthy donors or low-risk MDS. Moreover, incubation of high-risk MDS patient CD34+ cells with rapamycin decreased the in vitro clonogenic capability of these cells. In contrast, the phosphoinositide 3-kinase inhibitor, LY294002, did not significantly affect the clonogenic activity of high-risk MDS cells. Taken together, our results indicate that the Akt/mTOR pathway is critical for cell survival and proliferation in high-risk MDS patients. Therefore, this signaling network could become an interesting therapeutic target for treating more advanced MDS cases. [Cancer Res 2007;67(9):4287–94]
Thermal Cycling Enhances the Accumulation of a Temperature-Sensitive Biopolymer in Solid Tumors
Authors: Dreher Matthew R. , Liu Wenge , Michelich Charles R. , Dewhirst Mark W. , Chilkoti Ashutosh
Published: May 2007

The delivery of anticancer therapeutics to solid tumors remains a critical problem in the treatment of cancer. This study reports a new methodology to target a temperature-responsive macromolecular drug carrier, an elastin-like polypeptide (ELP) to solid tumors. Using a dorsal skin fold window chamber model and intravital laser scanning confocal microscopy, we show that the ELP forms micron-sized aggregates that adhere to the tumor vasculature only when tumors are heated to 41.5°C. Upon return to normothermia, the vascular particles dissolve into the plasma, increasing the vascular concentration, which drives more ELPs across the tumor blood vessel and significantly increases its extravascular accumulation. These observations suggested that thermal cycling of tumors would increase the exposure of tumor cells to ELP drug carriers. We investigated this hypothesis in this study by thermally cycling an implanted tumor in nude mice from body temperature to 41.5°C thrice within 1.5 h, and showed the repeated formation of adherent microparticles of ELP in the heated tumor vasculature in each thermal cycle. These results suggest that thermal cycling of tumors can be repeated multiple times to further increase the accumulation of a thermally responsive polymeric drug carrier in solid tumors over a single heat-cool cycle. More broadly, this study shows a new approach—tumor thermal cycling—to exploit stimuli-responsive polymers in vivo to target the tumor vasculature or extravascular compartment with high specificity. [Cancer Res 2007;67(9):4418–24]
Phosphoinositide-3-Kinase Signaling Controls S-Phase Kinase–Associated Protein 2 Transcription via E2F1 in Pancreatic Ductal Adenocarcinoma Cells
Authors: Reichert Maximilian , Saur Dieter , Hamacher Rainer , Schmid Roland M. , Schneider Günter
Published: May 2007

The phosphoinositide-3-kinase (PI3K)/AKT signaling pathway controls fundamental processes of cancer cell biology like proliferation and cell survival. The PI3K/AKT pathway is activated in pancreatic ductal adenocarcinoma (PDAC) cells. The molecular mechanisms linking PI3K signaling to the cell cycle machinery in PDAC cells are not investigated in detail. Using the PI3K inhibitor Ly294002 as well as small interfering RNA targeting AKT1 expression, we show that PI3K controls the proliferation and G1 phase progression of PDAC cells. Gene profiling revealed several important regulators of G1-S phase progression controlled by PI3K signaling like p21Cip1, S-phase kinase–associated protein 2 (SKP2), CDC25a, cyclin A, cyclin D2, CDK2, and cyclin E. We show that the F-box protein SKP2, an oncogene up-regulated in PDAC, is transcriptionally regulated by the PI3K/AKT1 pathway in PDAC cells. At the molecular level, the control of the SKP2 gene by PI3K is due to the regulation of E2F1 binding to the proximal SKP2 gene promoter. The complex and profound connection of PI3K/AKT1 signaling to the cell cycle qualifies this pathway as a suitable target for therapeutic intervention in PDAC. [Cancer Res 2007;67(9):4149–56]