bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitric Oxide in Physiologic Concentrations Targets the Translational Machinery to Increase the Proliferation of Human Breast Cancer Cells: Involvement of Mammalian Target of Rapamycin/eIF4E Pathway
Authors: Pervin Shehla , Singh Rajan , Hernandez Estebes , Wu Guoyao , Chaudhuri Gautam
Published: January 2007

Nitric oxide (NO) in nanomolar (nmol/L) concentrations is consistently detected in tumor microenvironment and has been found to promote tumorigenesis. The mechanism by which NO enhances tumor progression is largely unknown. In this study, we investigated the possible mechanisms and identified cellular targets by which NO increases proliferation of human breast cancer cell lines MDA-MB-231 and MCF-7. DETA-NONOate, a long acting NO donor, with a half-life of 20 h, was used. We found that NO (nmol/L) dramatically increased total protein synthesis in MDA-MB-231 and MCF-7 and also increased cell proliferation. NO specifically increased the translation of cyclin D1 and ornithine decarboxylase (ODC) without altering their mRNA levels or half-lives. Critical components in the translational machinery, such as phosphorylated mammalian target of rapamycin (mTOR) and its downstream targets, phosphorylated eukaryotic translation initiation factor and p70 S6 kinase, were up-regulated following NO treatment, and inhibition of mTOR with rapamycin attenuated NO induced increase of cyclin D1 and ODC. Activation of translational machinery was mediated by NO-induced up-regulation of the Raf/mitogen-activated protein/extracellular signal-regulated kinase (ERK) kinase/ERK (Raf/MEK/ERK) and phosphatidylinositol 3-kinase (PI-3 kinase)/Akt signaling pathways. Up-regulation of the Raf/MEK/ERK and PI-3 kinase/Akt pathways by NO was found to be mediated by activation of Ras, which was cyclic guanosine 3′,5′-monophosphate independent. Furthermore, inactivation of Ras by farnesyl transferase inhibitor or K-Ras small interfering RNA attenuated NO-induced increase in proliferation signaling and cyclin D1 and ODC translation, further confirming the involvement of Ras activation during NO-induced cell proliferation. [Cancer Res 2007;67(1):289–99]
Allelic Loss in a Minimal Region on Chromosome 16q24 Is Associated with Vitreous Seeding of Retinoblastoma
Authors: Gratias Sandrine , Rieder Harald , Ullmann Reinhard , Klein-Hitpass Ludger , Schneider Stephanie , Bölöni Réka , Kappler Martin , Lohmann Dietmar R.
Published: January 2007

In addition to RB1 gene mutations, retinoblastomas frequently show gains of 1q and 6p and losses of 16q. To identify suppressor genes on 16q, we analyzed 22 short tandem repeat loci in 58 patients with known RB1 mutations. A subset of tumors was also investigated by conventional and matrix comparative genomic hybridization. In 40 of 58 (69%) tumors, we found no loss of heterozygosity (LOH) at any 16q marker. LOH was detected in 18 of 58 (31%) tumors, including five with allelic imbalance at some markers. In one tumor LOH was only observed at 16q24. As the parental origin of allele loss was unbiased, an imprinted locus is unlikely to be involved. Analysis of gene expression by microarray hybridization and quantitative RT real-time PCR did not identify a candidate suppressor in 16q24. Cadherin 13 (CDH13), CBFA2T3, and WFDC1, which are candidate suppressors in other tumor entities with 16q24 loss, did not show loss of expression. In addition, mutation and methylation analysis showed no somatic alteration of CDH13. Results in all tumors with chromosome 16 alterations define a single minimal deleted region of 5.7 Mb in the telomeric part of 16q24 with the centromeric boundary defined by retention of heterozygosity for a single nucleotide variant in exon 10 of CDH13 (Mb 82.7). Interestingly, clinical presentation of tumors with and without 16q alterations was distinct. Specifically, almost all retinoblastomas with 16q24 loss showed diffuse intraocular seeding. This suggests that genetic alterations in the minimal deleted region are associated with impaired cell-to-cell adhesion. [Cancer Res 2007;67(1):408–16]
An Organometallic Protein Kinase Inhibitor Pharmacologically Activates p53 and Induces Apoptosis in Human Melanoma Cells
Authors: Smalley Keiran S.M. , Contractor Rooha , Haass Nikolas K. , Kulp Angela N. , Atilla-Gokcumen G. Ekin , Williams Douglas S. , Bregman Howard , Flaherty Keith T. , Soengas Maria S. , Meggers Eric , Herlyn Meenhard
Published: January 2007

Unlike other tumors, melanomas harbor wild-type (WT) p53 but exhibit impaired p53-dependent apoptosis. The mechanisms for the impaired p53 activation are poorly understood but may be linked to the high expression of the p53 suppressor Mdm2, which is found in >50% of melanoma lesions. Here, we describe an organometallic glycogen synthase kinase 3β (GSK3β) inhibitor (DW1/2) as a potent activator of p53 and inducer of cell death in otherwise highly chemoresistant melanoma cells. Using RNA interference and pharmacologic approaches, we show that p53 is required for the cytotoxic effects of this organometallic inhibitor. The DW1/2 compound was barely able to induce cell death in melanoma cells with p53 mutations, further confirming the requirement for p53-WT in the cytotoxic effects of the GSK3β inhibition. Mechanistic analysis of the p53-dependent cell death indicated an apoptotic mechanism involving depolarization of mitochondrial membrane potential, caspase cleavage, and elevated NOXA expression. The effect of p53 was not simply due to passive up-regulation of protein expression as adenoviral-mediated overexpression of p53 was not able to induce cell death. Treatment of melanoma cells with DW1/2 was instead found to decrease levels of Mdm2 and Mdm4. The importance of Mdm2 down-regulation in DW1/2-induced apoptosis was confirmed by treating the p53-WT cells with the p53/Mdm2 antagonist Nutlin-3. Taken together, our data provide a new strategy for the pharmacologic activation of p53 in melanoma, which may be a viable approach for overcoming apoptotic resistance in melanoma and offer new hope for rational melanoma therapy. [Cancer Res 2007;67(1):209–17]
TRAIL Induces Receptor-Interacting Protein 1–Dependent and Caspase-Dependent Necrosis-Like Cell Death under Acidic Extracellular Conditions
Authors: Meurette Olivier , Rebillard Amélie , Huc Laurence , Le Moigne Gwenaëlle , Merino Delphine , Micheau Olivier , Lagadic-Gossmann Dominique , Dimanche-Boitrel Marie-Thérèse
Published: January 2007

Tumor necrosis factor-α–related apoptosis-inducing ligand (TRAIL) is a potential anticancer agent that induces apoptosis in cancer cells but not in most normal cells. How tumor physiology, particularly acidic extracellular pH (pHe), would modify sensitivity of cancer cells to TRAIL-induced cell death is not known. We have previously shown that cancer cells, resistant to TRAIL-induced apoptosis at physiologic pHe (7.4), could be sensitized to TRAIL at acidic pHe (6.5). However, at this acidic pHe, cell death was necrotic. We show here that, in spite of a necrosis-like cell death morphology, caspases are activated and are necessary for TRAIL-induced cell death at acidic pHe in HT29 human colon cancer cells. Furthermore, we observed that, whereas receptor-interacting protein (RIP) was cleaved following TRAIL treatment at physiologic pHe (7.4), it was not cleaved following TRAIL treatment at acidic pHe (6.5). Moreover, RIP degradation by geldanamycin or decrease expression of RIP by small RNA interference transfection inhibited TRAIL-induced necrosis at acidic pHe, showing that RIP was necessary for this necrotic cell death pathway. We also show that RIP kinase activity was essential for this cell death pathway. Altogether, we show that, under acidic pHe conditions, TRAIL induces a necrosis-like cell death pathway that depends both on caspases and RIP kinase activity. Thus, our data suggest for the first time that RIP-dependent necrosis might be a major death pathway in TRAIL-based therapy in solid tumors with acidic pHe. [Cancer Res 2007;67(1):218–26]
Inactivated Sendai Virus Particles Eradicate Tumors by Inducing Immune Responses through Blocking Regulatory T Cells
Authors: Kurooka Masayuki , Kaneda Yasufumi
Published: January 2007

UV-inactivated, replication-defective Sendai virus particles [hemagglutinating virus of Japan envelope (HVJ-E)] injected into murine colon carcinoma (CT26) tumors growing in syngeneic BALB/c mice eradicated 60% to 80% of the tumors and obviously inhibited the growth of the remainder. Induced adaptive antitumor immune responses were dominant in the tumor eradication process because the effect was abrogated in severe combined immunodeficient mice. Murine and human dendritic cells underwent dose-dependent maturation by HVJ-E in vitro. Profiles of cytokines secreted by dendritic cells after HVJ-E stimulation showed that the amount of interleukin-6 (IL-6) released was comparable to that elicited by live HVJ. Real-time reverse transcription-PCR and immunohistochemistry revealed that HVJ-E induced a remarkable infiltration of dendritic cells and CD4+ and CD8+ T cells into tumors. In addition, CT26-specific CTLs were induced with the evidence of enhanced CD8+ T-cell activation in a CD4+CD25− T cell–dependent manner. On the other hand, conditioned medium from dendritic cells stimulated by HVJ-E rescued CD4+CD25− effector T-cell proliferation from Foxp3+CD4+CD25+ regulatory T cell (Treg)–mediated suppression and IL-6 was presumably dominant for this phenomenon. We also confirmed such rescue in mice treated with HVJ-E in vivo. Moreover, antitumor effect of HVJ-E was significantly reduced by an in vivo blockade of IL-6 signaling. This is the first report to show that HVJ-E alone can eradicate tumors and the mechanism through which it induces antitumor immune responses. Because it can enhance antitumor immunity and simultaneously remove Treg-mediated suppression, HVJ-E shows promise as a novel therapeutic for cancer immunotherapy. [Cancer Res 2007;67(1):227–36]
Daxx Cooperates with the Axin/HIPK2/p53 Complex to Induce Cell Death
Authors: Li Qinxi , Wang Xuan , Wu Xiaoling , Rui Yanning , Liu Wei , Wang Jifeng , Wang Xinghao , Liou Yih-Cherng , Ye Zhiyun , Lin Sheng-Cai
Published: January 2007

Daxx, a death domain–associated protein, has been implicated in proapoptosis, antiapoptosis, and transcriptional regulation. Many factors known to play critically important roles in controlling apoptosis and gene transcription have been shown to associate with Daxx, including the Ser/Thr protein kinase HIPK2, promyelocytic leukemia protein, histone deacetylases, and the chromatin remodeling protein ATRX. Although it is clear that Daxx may exert multiple functions, the underlying mechanisms remain far from clear. Here, we show that Axin, originally identified for its scaffolding role to control β-catenin levels in Wnt signaling, strongly associates with Daxx at endogenous levels. The Daxx/Axin complex formation is enhanced by UV irradiation. Axin tethers Daxx to the tumor suppressor p53, and cooperates with Daxx, but not DaxxΔAxin, which is unable to interact with Axin, to stimulate HIPK2-mediated Ser46 phosphorylation and transcriptional activity of p53. Interestingly, Axin and Daxx seem to selectively activate p53 target genes, with strong activation of PUMA, but not p21 or Bax. Daxx-stimulated p53 transcriptional activity was significantly diminished by small interfering RNA against Axin; Daxx fails to inhibit colony formation in Axin−/− cells. Moreover, UV-induced cell death was attenuated by the knockdown of Axin and Daxx. All these results show that Daxx cooperates with Axin to stimulate p53, and implicate a direct role for Axin, HIPK2, and p53 in the proapoptotic function of Daxx. We have hence unraveled a novel aspect of p53 activation and shed new light on the ultimate understanding of the Daxx protein, perhaps most pertinently, in relation to stress-induced cell death. [Cancer Res 2007;67(1):66–74]
Tumor Necrosis Factor-α Blocks Apoptosis in Melanoma Cells when BRAF Signaling Is Inhibited
Authors: Gray-Schopfer Vanessa C. , Karasarides Maria , Hayward Robert , Marais Richard
Published: January 2007

The protein kinase BRAF, a component of the RAS/RAF/mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK signaling pathway, regulates cell fate in response to extracellular signals. Activating mutations in BRAF occur in ∼70% of human melanomas. The active proteins stimulate constitutive pathway signaling, proliferation, and survival. Thus, inhibition of BRAF signaling in melanoma cells causes cell cycle arrest and induces cell death through apoptosis, validating BRAF as an important therapeutic target. Here, we show that the apoptosis induced by inhibition of BRAF signaling in melanoma cells can be prevented if the cells are treated with tumor necrosis factor (TNF)-α. This allows the cells to recover from the inhibition of BRAF signaling and reenter the cell cycle. This effect occurs due to a specific TNF-α and BRAF interaction because TNF-α does not prevent cell death in the presence of cisplatin, nitrogen mustard or thapsigargin. Furthermore, the cytokines Fas ligand, TNF-related apoptosis-inducing ligand, interleukin (IL)-1, and IL-6 do not prevent cell death when BRAF signaling is inhibited. The survival mechanism requires nuclear factor-κB (NF-κB) transcription factor activity, which is strongly induced by TNF-α in these cells. These findings suggest that drugs that target the BRAF/MEK pathway could be combined with agents that target TNF-α and/or NF-κB signaling to provide exciting new therapeutic opportunities for the treatment of melanoma. [Cancer Res 2007;67(1):122–9]
Pegylated Recombinant Human Arginase (rhArg-peg5,000mw) Inhibits the In vitro and In vivo Proliferation of Human Hepatocellular Carcinoma through Arginine Depletion
Authors: Cheng Paul Ning-Man , Lam Tin-Lun , Lam Wai-Man , Tsui Sam-Mui , Cheng Anthony Wai-Ming , Lo Wai-Hung , Leung Yun-Chung
Published: January 2007

Hepatocellular carcinoma (HCC) is believed to be auxotrophic for arginine through the lack of expression of argininosuccinate synthetase (ASS). The successful use of the arginine-depleting enzyme arginine deiminase (ADI) to treat ASS-deficient tumors has opened up new possibilities for effective cancer therapy. Nevertheless, many ASS-positive HCC cell lines are found to be resistant to ADI treatment, although most require arginine for proliferation. Thus far, an arginine-depleting enzyme for killing ASS-positive tumors has not been reported. Here, we provide direct evidence that recombinant human arginase (rhArg) inhibits ASS-positive HCCs. All the five human HCC cell lines we used were sensitive to rhArg but ADI had virtually no effect on these cells. They all expressed ASS, but not ornithine transcarbamylase (OTC), the enzyme that converts ornithine, the product of degradation of arginine with rhArg, to citrulline, which is converted back to arginine via ASS. Transfection of HCC cells with OTC resulted in resistance to rhArg. Thus, OTC expression alone may be sufficient to induce rhArg resistance in ASS-positive HCC cells. This surprising correlation between the lack of OTC expression and sensitivity of ASS-positive HCC cells shows that OTC-deficient HCCs are sensitive to rhArg-mediated arginine depletion. Therefore, pretreatment tumor gene expression profiling of ASS and OTC could aid in predicting tumor response to arginine depletion with arginine-depleting enzymes. We have also shown that the rhArg native enzyme and the pegylated rhArg (rhArg-peg5,000mw) gave similar anticancer efficacy in vitro. Furthermore, the growth of the OTC-deficient Hep3B tumor cells (ASS-positive and ADI-resistant) in mice was inhibited by treatment with rhArg-peg5,000mw, which is active alone and is synergistic in combination with 5-fluorouracil. Thus, our data suggest that rhArg-peg5,000mw is a novel agent for effective cancer therapy. [Cancer Res 2007;67(1):309–17]
[177Lu]Pertuzumab: Experimental Therapy of HER-2–Expressing Xenografts
Authors: Persson Mikael , Gedda Lars , Lundqvist Hans , Tolmachev Vladimir , Nordgren Hans , Malmström Per-Uno , Carlsson Jörgen
Published: January 2007

Pertuzumab (Omnitarg) is a novel antibody against HER-2, domain II. HER-2 is a tyrosine kinase receptor that is overexpressed in several carcinomas, especially breast cancer. Pertuzumab, labeled with the low-energy β emitter 177Lu, might be a candidate for targeted radiotherapy of disseminated HER-2–positive micrometastases. The radiolabeled antibody [177Lu]pertuzumab showed favorable targeting properties in BALB/c (nu/nu) mice with HER-2–overexpressing xenografts. The absorbed dose in tumors was more than five times higher than the absorbed dose in blood and more than seven times the absorbed dose in any other normal organ. Experimental therapy showed that [177Lu]pertuzumab delayed tumor progression compared with controls (no treatment, P < 0.0001; nonlabeled pertuzumab antibody, P < 0.0001; and 177Lu-labeled irrelevant antibody, P < 0.01). No adverse side effects of the treatment could be detected. Thus, the experimental results support the planning of clinical studies applying [177Lu]pertuzumab for therapy. [Cancer Res 2007;67(1):326–31]
Potentiation of Kinesin Spindle Protein Inhibitor–Induced Cell Death by Modulation of Mitochondrial and Death Receptor Apoptotic Pathways
Authors: Vijapurkar Ulka , Wang Wei , Herbst Ronald
Published: January 2007

Targeting the mitotic motor kinesin kinesin spindle protein (KSP) is a new strategy for cancer therapy. We have examined the molecular events induced by KSP inhibition and explored possible mechanisms of resistance and sensitization of tumor cells to KSP inhibitors. We found that KSP inhibition induced cell death primarily via activation of the mitochondrial death pathway. In HeLa cells, inhibition of KSP by small-molecule inhibitor monastrol resulted in mitotic arrest and rapid caspase activation. BclXL phosphorylation and loss of mitochondrial membrane potential was detected before significant caspase activation, which was required to trigger the subsequent apoptotic pathway. In A549 cells, however, KSP inhibition did not induce mitochondrial damage, significant caspase activity, or cell death. A549 cells aberrantly exited mitosis, following a prolonged drug-induced arrest, and arrested in a G1-like state with 4N DNA content in a p53-dependent manner. Overexpression of BclXL provided a protective mechanism, and its depletion rescued the apoptotic response to monastrol. In addition, Fas receptor was up-regulated in A549 cells in response to monastrol. Treatment with Fas receptor agonists sensitized the cells to monastrol-induced cell death, following exit from mitosis. Thus, activation of the death receptor pathway offered another mechanism to enhance KSP inhibitor–induced apoptosis. This study has elucidated cellular responses induced by KSP inhibitors, and the results provide insights for a more effective cancer treatment with these agents. [Cancer Res 2007;67(1):237–45]
Aberrant Splicing of Cyclin-Dependent Kinase–Associated Protein Phosphatase KAP Increases Proliferation and Migration in Glioblastoma
Authors: Yu Yi , Jiang Xiuli , Schoch Brad S. , Carroll Rona S. , Black Peter M. , Johnson Mark D.
Published: January 2007

The cyclin-dependent kinase (Cdk)–associated protein phosphatase KAP is a dual-specificity phosphatase of which the only known function is to dephosphorylate Cdk2 and inhibit cell cycle progression. Paradoxically, we find increased KAP mRNA expression in malignant astrocytomas, which correlates with increasing histologic grade and decreased patient survival. We have resolved this apparent paradox with the discovery of aberrant KAP splicing in malignant astrocytomas that leads to increased expression of KAP-related transcripts but decreased KAP protein expression. In addition, the aberrant splicing generates a dominant negative KAP variant that increases proliferation. We provide the first evidence that KAP not only regulates proliferation but also inhibits migration by decreasing cdc2 mRNA and protein expression. The effect of KAP on cdc2 expression requires its phosphatase activity but does not involve direct dephosphorylation of cdc2. Thus, KAP regulates both cdc2-dependent migration and Cdk2-dependent proliferation, and its loss due to aberrant splicing increases malignancy in human gliomas. [Cancer Res 2006;67(1):130–8]
Mechanisms of Mitotic Cell Death Induced by Chemotherapy-Mediated G2 Checkpoint Abrogation
Authors: Vogel Celia , Hager Christian , Bastians Holger
Published: January 2007

The novel concept of anticancer treatment termed “G2 checkpoint abrogation” aims to target p53-deficient tumor cells and is currently explored in clinical trials. The anticancer drug UCN-01 is used to abrogate a DNA damage–induced G2 cell cycle arrest leading to mitotic entry and subsequent cell death, which is poorly defined as “mitotic cell death” or “mitotic catastrophe.” We show here that UCN-01 treatment results in a mitotic arrest that requires an active mitotic spindle checkpoint, involving the function of Mad2, Bub1, BubR1, Mps1, Aurora B, and survivin. During the mitotic arrest, hallmark parameters of the mitochondria-associated apoptosis pathway become activated. Interestingly, this apoptotic response requires the spindle checkpoint protein Mad2, suggesting a proapoptotic function for Mad2. However, although survivin and Aurora B are also required for the mitotic arrest, both proteins are part of an antiapoptotic pathway that restrains the UCN-01–induced apoptosis by promoting hyperphosphorylation of Bcl-2 and by inhibiting the activation of Bax. Consequently, inhibition of the antiapoptotic pathway by genetic ablation of survivin or by pharmacologic inhibitors of Aurora B or cyclin-dependent kinase 1 lead to a significant enhancement of apoptosis and therefore act synergistically with UCN-01. Thus, by defining the mechanism of cell death on G2 checkpoint abrogation we show a highly improved strategy for an anticancer treatment by the combined use of UCN-01 with abrogators of the survivin/Aurora B–dependent antiapoptotic pathway that retains the selectivity for p53-defective cancer cells. [Cancer Res 2007;67(1):339–45]
Induction of Human ArylamineN-Acetyltransferase Type I by Androgens in Human Prostate Cancer Cells
Authors: Butcher Neville J. , Tetlow Natasha L. , Cheung Catherine , Broadhurst Gysell M. , Minchin Rodney F.
Published: January 2007

Human arylamine N-acetyltransferases (NAT) bioactivate arylamine and heterocyclic amine carcinogens present in red meat and tobacco products. As a result, factors that regulate expression of NATs have the potential to modulate cancer risk in individuals exposed to these classes of carcinogens. Because epidemiologic studies have implicated well-done meat consumption as a risk factor for prostate cancer, we have investigated the effects of androgens on the expression of arylamine N-acetyltransferase type I (NAT1). We show that NAT1 activity is induced by R1881 in androgen receptor (AR)–positive prostate lines 22Rv1 and LNCaP, but not in the AR-negative PC-3, HK-293, or HeLa cells. The effect of R1881 was dose dependent, with an EC50 for R1881 of 1.6 nmol/L. Androgen up-regulation of NAT1 was prevented by the AR antagonist flutamide. Real-time PCR showed a significant increase in NAT1 mRNA levels for R1881-treated cells (6.60 ± 0.80) compared with vehicle-treated controls (1.53 ± 0.17), which was not due to a change in mRNA stability. The increase in NAT1 mRNA was attenuated by concurrent cycloheximide treatment, suggesting that the effect of R1881 may not be by direct transcriptional activation of NAT1. The dominant NAT1 transcript present following androgen treatment was type IIA, indicating transcriptional activation from the major NAT1 promoter P1. A series of luciferase reporter deletions mapped the androgen responsive motifs to a 157-bp region of P1 located 745 bases upstream of the first exon. These results show that human NAT1 is induced by androgens, which may have implications for cancer risk in individuals. [Cancer Res 2007;67(1):85–92]
Multidrug Resistance Protein 4 Protects Bone Marrow, Thymus, Spleen, and Intestine from Nucleotide Analogue–Induced Damage
Authors: Belinsky Martin G. , Guo Ping , Lee Kun , Zhou Feng , Kotova Elena , Grinberg Alex , Westphal Heiner , Shchaveleva Irina , Klein-Szanto Andres , Gallo James M. , Kruh Gary D.
Published: January 2007

Nucleoside-based analogues are mainstays in the treatment of cancer, viral infections, and inflammatory diseases. Recent studies showing that the ATP-binding cassette transporter, multidrug resistance protein 4, is able to efflux nucleoside and nucleotide analogues from transfected cells suggests that the pump may affect the efficacy of this class of agents. However, the in vivo pharmacologic functions of the pump are largely unexplored. Here, using Mrp4−/− mice as a model system, and the nucleotide analogue, 9′-(2′-phosphonylmethoxyethyl)-adenine (PMEA) as a probe, we investigate the ability of Mrp4 to function in vivo as an endogenous resistance factor. In the absence of alterations in plasma PMEA levels, Mrp4-null mice treated with PMEA exhibit increased lethality associated with marked toxicity in several tissues. Affected tissues include the bone marrow, spleen, thymus, and gastrointestinal tract. In addition, PMEA penetration into the brain is increased in Mrp4−/− mice. These findings indicate that Mrp4 is an endogenous resistance factor, and that the pump may be a component of the blood-brain barrier for nucleoside-based analogues. This is the first demonstration that an ATP-binding cassette transporter can affect in vivo tissue sensitivity towards this class of agents. [Cancer Res 2007;67(1):262–8]
Bin1 Ablation in Mammary Gland Delays Tissue Remodeling and Drives Cancer Progression
Authors: Chang Mee Young , Boulden Janette , Sutanto-Ward Erika , Duhadaway James B. , Soler Alejandro Peralta , Muller Alexander J. , Prendergast George C.
Published: January 2007

Genes that modify oncogenesis may influence dormancy versus progression in cancer, thereby affecting clinical outcomes. The Bin1 gene encodes a nucleocytosolic adapter protein that interacts with and suppresses the cell transforming activity of Myc. Bin1 is often attenuated in breast cancer but its ability to negatively modify oncogenesis or progression in this context has not been gauged directly. In this study, we investigated the effects of mammary gland–specific deletion of Bin1 on initiation and progression of breast cancer in mice. Bin1 loss delayed the outgrowth and involution of the glandular ductal network during pregnancy but had no effect on tumor susceptibility. In contrast, in mice where tumors were initiated by the ras-activating carcinogen 7,12-dimethylbenz(a)anthracene, Bin1 loss strongly accentuated the formation of poorly differentiated tumors characterized by increased proliferation, survival, and motility. This effect was specific as Bin1 loss did not accentuate progression of tumors initiated by an overexpressed mouse mammary tumor virus-c-myc transgene, which on its own produced poorly differentiated and aggressive tumors. These findings suggest that Bin1 loss cooperates with ras activation to drive progression, establishing a role for Bin1 as a negative modifier of oncogenicity and progression in breast cancer. [Cancer Res 2007;67(1):100–7]
c-Jun NH2-Terminal Kinase 2 Is Required for Ras Transformation Independently of Activator Protein 1
Authors: Nielsen Christina , Thastrup Jacob , Bøttzauw Trine , Jäättelä Marja , Kallunki Tuula
Published: January 2007

Active Ras oncogene is expressed in ∼30% of human cancers. Yet, very little is known about the molecular mechanisms responsible for its transforming potential. Here, we show that H-Ras-mediated transformation requires isoform 2 of the c-Jun-NH2-terminal kinase (JNK). H-Ras-transduced JNK2-deficient (Jnk2−/−) murine embryonic fibroblasts (MEFs) were severely inhibited in colony formation and growth in soft agar in vitro as well as in tumor formation in immunodeficient mice as compared with corresponding Jnk1−/− and wild-type MEFs. Accordingly, the RNA interference–based depletion of JNK2 form wild-type MEFs also resulted in defective Ras transformation. The extra barrier against H-Ras transformation in Jnk2−/− MEFs was not due to their inability to inactivate p53 signaling because all JNK2-deficient MEF lines had lost p19Arf. Furthermore, expression of the E6 protein of the human papilloma virus failed to overcome the transformation defect. It could, however, be overcome by coexpression of H-Ras with the SV40 large T antigen or c-Myc. Surprisingly, the H-Ras-transduced JNK2-deficient MEFs exhibited higher activity of activator protein-1 and higher levels of c-Jun expression compared with H-Ras-transduced JNK1-deficient or wild-type cells, indicating that the key target of JNK2 during Ras transformation was divergent from activator protein-1. These results clearly show that a single kinase, JNK2, could control Ras transformation and thus point out a vulnerable control point that may prove important for the tumor development in general. [Cancer Res 2007;67(1):178–85]
Inhibition of Histone Deacetylation Does Not Block Resilencing of p16 after 5-Aza-2′-Deoxycytidine Treatment
Authors: Egger Gerda , Aparicio Ana M. , Escobar Sonia G. , Jones Peter A.
Published: January 2007

Epigenetic drugs are in use in clinical trials of various human cancers and are potent at reactivating genes silenced by DNA methylation and chromatin modifications. We report here the analysis of a set of normal fibroblast and cancer cell lines after combination treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (5-aza-CdR) and the histone deacetylase inhibitor 4-phenylbutyric acid (PBA). Low doses of the drug combination caused cell cycle arrest, whereas high doses induced apoptosis in T24 bladder carcinoma cells. Both p16 (CDKN2A/INK4) and p21 (CIP1/SDI1/WAF1) expression were induced to similar levels in normal and cancer cells in a dose-dependent fashion after combination treatments. We detected a distinct increase of histone H3 acetylation at lysine 9/14 near the transcription start sites, in both LD419 normal fibroblasts and T24 bladder carcinoma cells, whereas the acetylation changes in the p21 locus were less apparent. Interestingly, the levels of trimethylation of histone H3 on lysine 9, which usually marks inactive chromatin regions and was associated with the p16 promoter in silenced T24 cells, did not change after drug treatments. Furthermore, we provide evidence that the remethylation of the p16 promoter CpG island in T24 cells after 5-aza-CdR treatment cannot be halted by subsequent continuous PBA treatment. The p16 gene is resilenced with kinetics similar to 5-aza-CdR only–treated cells, which is also marked by a localized loss of histone acetylation at the transcription start site. Altogether, our data provide new insights into the mechanism of epigenetic drugs and have important implications for epigenetic therapy. [Cancer Res 2007;67(1):346–53]
Transgenic Overexpression of RasGRP1 in Mouse Epidermis Results in Spontaneous Tumors of the Skin
Authors: Oki-Idouchi Carolyn E. , Lorenzo Patricia S.
Published: January 2007

RasGRP1 is a guanine nucleotide exchange factor for Ras and a receptor of the second messenger diacylglycerol and its ultrapotent analogues, the phorbol esters. We have recently shown expression of RasGRP1 in the epidermal keratinocytes where it can mediate Ras activation in response to the phorbol ester 12-O-tetradecanoylphorbol-13-acetate, a well-known mouse skin tumor promoter. To explore the participation of RasGRP1 in skin carcinogenesis, we targeted the overexpression of RasGRP1 to basal epidermal keratinocytes using the keratin 5 promoter. These transgenic mice were viable and indistinguishable from their littermates, with normal differentiation and skin architecture. However, a percentage of the adult transgenic population developed spontaneous skin tumors, mainly squamous cell papillomas. The transgene was detected in the tumors as well as in primary keratinocytes isolated from transgenic mice. The transgenic keratinocytes also displayed elevated levels of active, GTP-loaded Ras compared with the levels observed in keratinocytes derived from wild-type littermates. We noticed a correlation between tumor incidence and wounding, which suggests that RasGRP1 overexpression may confer sensitivity to promotional stimuli, like wound repair mechanisms. Interestingly, we also found elevated levels of granulocyte colony-stimulating factor in conditioned media derived from transgenic keratinocytes subjected to in vitro wounding. Taken together, these data are the first to provide evidence of a novel role for RasGRP1 in skin carcinogenesis and suggest that RasGRP1 may participate in tumorigenesis through modulation of Ras and autocrine pathways. [Cancer Res 2007;67(1):276–80]
Amplification of Tumor Hypoxic Responses by Macrophage Migration Inhibitory Factor–Dependent Hypoxia-Inducible Factor Stabilization
Authors: Winner Millicent , Koong Albert C. , Rendon Beatriz E. , Zundel Wayne , Mitchell Robert A.
Published: January 2007

Low oxygen tension–mediated transcription by hypoxia-inducible factors (HIF) has been reported to facilitate tumor progression, therapeutic resistance, and metastatic adaptation. One previously described target of hypoxia-mediated transcription is the cytokine/growth factor macrophage migration inhibitory factor (MIF). In studies designed to better understand hypoxia-stimulated MIF function, we have discovered that not only is MIF induced by hypoxia in pancreatic adenocarcinoma but MIF is also necessary for maximal hypoxia-induced HIF-1α expression. Cells lacking MIF are defective in hypoxia- and prolyl hydroxylase inhibitor–induced HIF-1α stabilization and subsequent transcription of glycolytic and angiogenic gene products. Moreover, COP9 signalosome subunit 5 (CSN5), a component of the COP9 signalosome previously reported to functionally interact with MIF, has recently been shown to interact with and stabilize HIF-1α. Our results indicate that MIF interacts with CSN5 in pancreatic cancer cells and that MIF-depleted cells display marked defects in hypoxia-induced CSN5/HIF-1α interactions. This functional interdependence between HIF-1α and MIF may represent an important and previously unrecognized protumorigenic axis. [Cancer Res 2007;67(1):186–93]
Heterozygous Deletion of Mitotic Arrest–Deficient Protein 1 (MAD1) Increases the Incidence of Tumors in Mice
Authors: Iwanaga Yoichi , Chi Ya-Hui , Miyazato Akiko , Sheleg Sergey , Haller Kerstin , Peloponese Jean-Marie , Li Yan , Ward Jerrold M. , Benezra Robert , Jeang Kuan-Teh
Published: January 2007

Mitotic arrest–deficient protein 1 (MAD1) is a component of the mitotic spindle assembly checkpoint. We have created a knockout mouse model to examine the physiologic consequence of reduced MAD1 function. Mad1+/− mice were successfully generated, but repeated paired mating of Mad1+/− with Mad1+/− mice failed to produce a single Mad1−/− animal, suggesting that the latter genotype is embryonic lethal. In aging studies conducted for >18 months, Mad1+/− mice compared with control wild-type (wt) littermates showed a 2-fold higher incidence of constitutive tumors. Moreover, 42% of Mad1+/− (P < 0.03), but 0% of wt, mice developed neoplasia after treatment with vincristine, a microtubule depolymerization agent. Mad1+/− mouse embryonic fibroblasts (MEF) were found to be more prone than wt cells to become aneuploid; Mad1+/−, but not wt, MEFs produced fibrosarcomas when explanted into nude mice. Our results indicate an essential MAD1 function in mouse development and correlate Mad1 haploinsufficiency with increased constitutive tumors. [Cancer Res 2007;67(1):160–6]
High Number of Intraepithelial CD8+ Tumor-Infiltrating Lymphocytes Is Associated with the Absence of Lymph Node Metastases in Patients with Large Early-Stage Cervical Cancer
Authors: Piersma Sytse J. , Jordanova Ekaterina S. , van Poelgeest Mariëtte I.E. , Kwappenberg Kitty M.C. , van der Hulst Jeanette M. , Drijfhout Jan W. , Melief Cornelis J.M. , Kenter Gemma G. , Fleuren Gert Jan , Offringa Rienk , van der Burg Sjoerd H.
Published: January 2007

In a prospective study, we have examined the tumor-specific immune response in a group of 59 patients with human papillomavirus (HPV) 16-positive (HPV16+)–induced or HPV18+-induced cervical cancer. Local antitumor immunity was analyzed by the enumeration of tumor-infiltrating dendritic cells and CD4+, CD8+, and regulatory T cells as well as by calculation of the ratio of CD8+/CD4+ T cells and CD8+/regulatory T cells. Systemic tumor-specific immunity was assessed by determination of the HPV E6- and/or E7-specific T-cell response in the blood of these patients. Finally, these variables were evaluated with respect to known histopathologic prognostic variables, including the absence (LN−) or presence (LN+) of lymph node metastases. Stratification according to the lymph node status of patients revealed a significantly stronger CD8+ T-cell tumor infiltration, a higher CD8+/CD4+ T-cell ratio, and higher CD8+/regulatory T-cell ratio in the group of patients in which the tumor failed to metastasize to the tumor-draining lymph node. Subdivision according to the presence (IR+) or absence (IR−) of circulating HPV-specific T cells disclosed that the highest number of tumor-infiltrating CD8+ T cells was found in the group of LN− patients displaying a concomitant systemic tumor-specific immune response (LN−IR+). CD8+ T-cell infiltration in LN−IR− patients was comparable with that of LN+ patients. In cervical cancer, the absence of lymph node metastases is strongly associated with a better prognosis. Our data indicate that, especially in a subgroup of LN− patients, a strong and effective interaction between immune system and tumor exists. This subgroup of cervical cancer patients may have the best prognosis. [Cancer Res 2007;67(1):354–61]
hTERT Is Expressed in Cancer Cell Lines Despite Promoter DNA Methylation by Preservation of Unmethylated DNA and Active Chromatin around the Transcription Start Site
Authors: Zinn Rebekah L. , Pruitt Kevin , Eguchi Sayaka , Baylin Stephen B. , Herman James G.
Published: January 2007

hTERT, which encodes the catalytic subunit of telomerase and is expressed in most immortalized and cancer cells, has been reported to have increased DNA methylation in its promoter region in many cancers. This pattern is inconsistent with observations that DNA methylation of promoter CpG islands is typically associated with gene silencing. Here, we provide a comprehensive analysis of promoter DNA methylation, chromatin patterns, and expression of hTERT in cancer and immortalized cells. Methylation-specific PCR and bisulfite sequencing of the hTERT promoter in breast, lung, and colon cancer cells show that all cancer cell lines retain alleles with little or no methylation around the transcription start site despite being densely methylated in a region 600 bp upstream of the transcription start site. By real-time reverse transcription-PCR, all cancer cell lines express hTERT. Chromatin immunoprecipitation (ChIP) analysis reveals that both active (acetyl-H3K9 and dimethyl-H3K4) and inactive (trimethyl-H3K9 and trimethyl-H3K27) chromatin marks are present across the hTERT promoter. However, using a novel approach combining methylation analysis of ChIP DNA, we show that active chromatin marks are associated with unmethylated DNA, whereas inactive marks of chromatin are associated with methylated DNA in the region around the transcription start site. These results show that DNA methylation patterns of the hTERT promoter (−150 to +150 around the transcription start) are consistent with the usual dynamics of gene expression in that the absence of methylation in this region and the association with active chromatin marks allow for the continued expression of hTERT. [Cancer Res 2007;67(1):194–201]
Tumor-Targeted Enzyme/Prodrug Therapy Mediates Long-term Disease-Free Survival of Mice Bearing Disseminated Neuroblastoma
Authors: Danks Mary K. , Yoon K. Jin , Bush Rebecca A. , Remack Joanna S. , Wierdl Monika , Tsurkan Lyudmila , Kim Seung U. , Garcia Elizabeth , Metz Marianne Z. , Najbauer Joseph , Potter Philip M. , Aboody Karen S.
Published: January 2007

Neural stem cells and progenitor cells migrate selectively to tumor loci in vivo. We exploited the tumor-tropic properties of HB1.F3.C1 cells, an immortalized cell line derived from human fetal telencephalon, to deliver the cDNA encoding a secreted form of rabbit carboxylesterase (rCE) to disseminated neuroblastoma tumors in mice. This enzyme activates the prodrug CPT-11 more efficiently than do human enzymes. Mice bearing multiple tumors were treated with rCE-expressing HB1.F3.C1 cells and schedules of administration of CPT-11 that produced levels of active drug (SN-38) tolerated by patients. Both HB1.F3.C1 cells and CPT-11 were given i.v. None of the untreated mice and 30% of mice that received only CPT-11 survived long term. In contrast, 90% of mice treated with rCE-expressing HB1.F3.C1 cells and 15 mg/kg CPT-11 survived for 1 year without detectable tumors. Plasma carboxylesterase activity and SN-38 levels in mice receiving both rCE-expressing HB1.F3.C1 cells (HB1.F3.C1/AdCMVrCE) and CPT-11 were comparable with those in mice receiving CPT-11 only. These data support the hypothesis that the antitumor effect of the described neural stem/progenitor cell–directed enzyme prodrug therapy (NDEPT) is mediated by production of high concentrations of active drug selectively at tumor sites, thereby maximizing the antitumor effect of CPT-11. NDEPT approaches merit further investigation as effective, targeted therapy for metastatic tumors. We propose that the described approach may have greatest use for eradicating minimum residual disease. [Cancer Res 2007;67(1):22–5]
Human Monocytes, but not Dendritic Cells Derived from Them, Are Defective in Base Excision Repair and Hypersensitive to Methylating Agents
Authors: Briegert Manuela , Kaina Bernd
Published: January 2007

Monocytes and dendritic cells are key players in the immune response. Because dendritic cells drive the tumor host defense, it is important that monocytes and dendritic cells survive cytotoxic tumor therapy. Although most of the anticancer drugs target DNA, the DNA repair capacity of monocytes and dendritic cells has not yet been investigated. We studied the sensitivity of monocytes and monocyte-derived dendritic cells against various genotoxic agents and found monocytes to be more sensitive to overall cell kill and apoptosis upon exposure to methylating agents (e.g., N-methyl-N′-nitro-N-nitrosoguanidine, methyl methanesulfonate, and the anticancer drug temozolomide). On the other hand, upon treatment with the cross-linking chemotherapeutics fotemustine, mafosfamide, and cisplatin, monocytes and dendritic cells responded in the same way. Monocytes were also more sensitive than lymphocytes. The data indicate a defect in the repair of DNA methylation damage in monocytes. Because the expression of the repair protein O6-methylguanine-DNA methyltransferase was higher in monocytes than in dendritic cells, and because its inhibition by O6-benzylguanine had no effect on the sensitivity of monocytes, we investigated the base excision repair (BER) pathway. In contrast to dendritic cells, monocytes are unable to perform BER following exposure to methylating agents. Expression studies revealed that monocytes lack XRCC1 and ligase IIIα, whereas dendritic cells, similar to human lymphocytes, express these repair proteins at a high level. The data revealed a DNA repair defect in a specific human cell population. The BER defect in monocytes may cause them to be selectively killed during tumor therapy with alkylating agents, provoking hematotoxicity and sustained immunosuppression. [Cancer Res 2007;67(1):26–31]
Akt1 Ablation Inhibits, whereas Akt2 Ablation Accelerates, the Development of Mammary Adenocarcinomas in Mouse Mammary Tumor Virus (MMTV)-ErbB2/Neu and MMTV-Polyoma Middle T Transgenic Mice
Authors: Maroulakou Ioanna G. , Oemler William , Naber Stephen P. , Tsichlis Philip N.
Published: January 2007

Ample evidence to date links the phosphatidylinositol 3-kinase–regulated protein kinase Akt with the induction and progression of human cancer, including breast cancer. However, there are three Akt isoforms with limited information about their specificity during oncogenesis. This study addresses the role of the three isoforms in polyoma middle T (PyMT) and ErbB2/Neu-driven mammary adenocarcinomas in mice. The effects of ablation of Akt1, Akt2, and Akt3 on the induction and the biology of these tumors were dramatically different, with ablation of Akt1 inhibiting, ablation of Akt2 accelerating, and ablation of Akt3 having a small, not statistically significant, inhibitory effect on tumor induction by both transgenes. Whereas PyMT-induced tumors are all invasive, Akt1−/−Neu–induced tumors are more invasive than Akt2−/−Neu–induced tumors. Invasiveness, however, does not always correlate with metastasis. Ablation of individual Akt isoforms does not affect the development of the mammary gland during puberty or the expression of the transgenes. Akt ablation, therefore, influences tumor induction by modulating transgene-induced oncogenic signaling. Immunostaining for Ki-67 and cyclin D1 and terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling assays on tissue sections revealed that the delay of tumor induction in Akt1 knockout mice is due to the inhibitory effects of Akt1 ablation on cell proliferation and survival. Given that these animal models exhibit significant similarities to human breast cancer, the results of the present study may have significant translational implications because they may influence how Akt inhibitors will be used in the treatment of human cancer. [Cancer Res 2007;67(1):167–77]
Tri-Iodothyronine as a Stimulator of Liver Regeneration after Partial and Subtotal Hepatectomy
Authors: Bockhorn M. , Frilling A. , Benkö T. , Best J. , Sheu S.-Y. , Trippler M. , Schlaak J.F. , Broelsch C.E.
Published: January 2007

Background: Tri-iodothyronine (T3) has been shown to be a hepatic mitogen. We investigated whether exogenous application of T3 improves liver regeneration after 70% partial hepatectomy (PH) and confers a survival advantage after 90% subtotal hepatectomy (SH) in rats and whether this is associated with the stimulation of angiogenesis. Methods: Rats were subjected to PH or SH 10 days after injection of a single dose of T3. Liver body weight ratio (LBR), hepatic proliferation (Ki-67), biochemical markers as well as vascular endothelial growth factor (VEGF) expression were assessed by immunohistochemistry. Gene expression of pathogenic relevant genes was determined by customized cDNA arrays and quantitative RT-PCR. Results: T3-treated rats showed an increased LBR and Ki-67 index after PH and SH, which reached statistical significance compared to placebo-treated rats (p < 0.05). On the transcriptional level, T3-treated rats had an increased expression of VEGF as demonstrated by immunohistochemistry, which was associated with a higher expression of its receptor Flt-1. Conclusions: Exogenous administration of T3 ameliorates liver regeneration after 70% PH and 90% SH, possibly due to stimulation of angiogenesis. Therefore, its clinical use might be of interest due to its excellent general practicability.
Master Narratives and the Future of Christianity
Authors: Martin David
Published: January 2007

The article sets the future of Christianity within the context of different master narratives, beginning with those employed by social scientists, scrutinizing some of their key characteristics. It then considers characteristics of master narratives in general, before looking at paradoxes of universalism and particularity, the collective and the individual, in relation to the inherent character of political reason.