bluuebunny/crossref_metadata_2025 huggingface dataset:
Haploinsufficiency of Krüppel-Like Factor 5 Rescues the Tumor-Initiating Effect of the ApcMin Mutation in the Intestine
Authors: McConnell Beth B. , Bialkowska Agnieszka B. , Nandan Mandayam O. , Ghaleb Amr M. , Gordon Frank J. , Yang Vincent W.
Published: May 2009

Inactivation of the tumor suppressor adenomatous polyposis coli, with the resultant activation of β-catenin, is the initiating event in the development of a majority of colorectal cancers. Krüppel-like factor 5 (KLF5), a proproliferative transcription factor, is highly expressed in the proliferating intestinal crypt epithelial cells. To determine whether KLF5 contributes to intestinal adenoma formation, we examined tumor burdens in ApcMin/+ mice and ApcMin/+/Klf5+/− mice. Compared with ApcMin/+ mice, ApcMin/+/Klf5+/− mice had a 96% reduction in the number of intestinal adenomas. Reduced tumorigenicity in the ApcMin/+/Klf5+/− mice correlated with reduced levels and nuclear localization of β-catenin as well as reduced expression of two β-catenin targets, cyclin D1 and c-Myc. In vitro studies revealed a physical interaction between KLF5 and β-catenin that enhanced the nuclear localization and transcriptional activity of β-catenin. Thus, KLF5 is necessary for the tumor-initiating activity of β-catenin during intestinal adenoma formation in ApcMin/+ mice, and reduced expression of KLF5 offsets the tumor-initiating activity of the ApcMin mutation by reducing the nuclear localization and activity of β-catenin. [Cancer Res 2009;69(10):4125–33]
VEGF-A Induces Angiogenesis by Perturbing the Cathepsin-Cysteine Protease Inhibitor Balance in Venules, Causing Basement Membrane Degradation and Mother Vessel Formation
Authors: Chang Sung-Hee , Kanasaki Keizo , Gocheva Vasilena , Blum Galia , Harper Jay , Moses Marsha A. , Shih Shou-Ching , Nagy Janice A. , Joyce Johanna , Bogyo Matthew , Kalluri Raghu , Dvorak Harold F.
Published: May 2009

Tumors initiate angiogenesis primarily by secreting vascular endothelial growth factor (VEGF-A164). The first new vessels to form are greatly enlarged, pericyte-poor sinusoids, called mother vessels (MV), that originate from preexisting venules. We postulated that the venular enlargement necessary to form MV would require a selective degradation of their basement membranes, rigid structures that resist vascular expansion. To identify the specific proteases responsible for MV formation, we induced angiogenesis in mouse tissues with an adenoviral vector expressing VEGF-A164 (Ad-VEGF-A164) or with VEGF-A–secreting TA3/St mammary tumors. We found that MV formation resulted from greatly increased activity of cathepsins (B>S>L) in venules transitioning into MV, as well as from a reciprocal decrease in the expression of several cysteine protease inhibitors (CPI), stefin A and cystatins B and C, by these same venules. Using a fluorescence probe that selectively binds cellular sites of cathepsin protease activity in vivo, we showed that increased cathepsin activity was localized exclusively to perivenular cells, not to venule endothelial cells. CPI strikingly inhibited angiogenesis in the Matrigel assay, and Ad-VEGF-A164–induced angiogenesis was reduced by ∼50% in cathepsin B–null mice. Thus, VEGF-A, whether expressed by interstitial cells infected with an adenoviral vector or by tumor cells, upsets the normal cathepsin-CPI balance in nearby venules, leading to degradation of their basement membranes, an important first step in angiogenesis. [Cancer Res 2009;69(10):4537–44]
The Vascular Endothelial Growth Factor Receptor Inhibitor PTK787/ZK222584 Inhibits Aromatase
Authors: Banerjee Susana , Zvelebil Marketa , Furet Pascal , Mueller-Vieira Ursula , Evans Dean B. , Dowsett Mitch , Martin Lesley-Ann
Published: May 2009

Endocrine therapy is well established for the treatment of breast cancer, and antiangiogenic agents are showing considerable promise. Targeting the vascular endothelial growth factor (VEGF) and estrogen receptor (ER) signaling pathways concomitantly may provide enhanced therapeutic benefit in ER-positive breast cancer. Therefore, the effects of the VEGF receptor (VEGFR) tyrosine kinase inhibitor PTK787/ZK222584 (PTK/ZK) were investigated using human breast cancer cell lines engineered to express aromatase. As expected in this system, estrogen (E2) or androstenedione induced a proliferative response and increased ER-mediated transcription in ER-positive cell lines expressing aromatase. However, surprisingly, in the presence of androstenedione, PTK/ZK suppressed both the androstenedione-stimulated proliferation and ER-mediated transcription. PTK/ZK alone and in the presence of E2 had no observable effect on proliferation or ER-mediated transcription. These effects result from PTK/ZK having previously unrecognized antiaromatase activity and PTK/ZK being a competitive aromatase inhibitor. Computer-assisted molecular modeling showed that PTK/ZK could potentially bind directly to aromatase. The demonstration that PTK/ZK inhibits aromatase and VEGFR indicates that agents cross-inhibiting two important classes of targets in breast cancer could be developed. [Cancer Res 2009;69(11):4716–23]
A Regulatory Mechanism for RSK2 NH2-Terminal Kinase Activity
Authors: Cho Yong-Yeon , Yao Ke , Pugliese Angelo , Malakhova Margarita L. , Bode Ann M. , Dong Zigang
Published: May 2009

Our previous findings indicated that RSK2 plays a critical role in proliferation and cell transformation induced by tumor promoters, such as epidermal growth factor or 12-O-tetradecanoylphorbol-13-acetate, and that kaempferol, a natural compound found in edible plants, selectively inhibits RSK2 activity. However, the molecular mechanism for RSK2 activation is unclear. Herein, we provide evidence showing that NH2-terminal kinase domain (NTD) activation of RSK2 is required for the activation of the extracellular signal-regulated kinase–mediated COOH-terminal kinase domain (CTD). We also found that the NTD plays a key role in substrate phosphorylation and that kaempferol binds with the NTD but not the CTD in both the active and inactive forms. Homology modeling of the RSK2 NH2-terminal domain and small-molecule docking, validated by mutagenesis experiments, clearly showed that Val82 and Lys100 are critical amino acids for kaempferol binding and RSK2 activity. Furthermore, immunohistofluorescence and Western blot results indicated that the RSK2 protein level is markedly higher in cancer cell lines as well as cancer tissues compared with nonmalignant cell lines or normal tissues. In addition, kaempferol inhibited proliferation of malignant human cancer cell lines, including A431, SK-MEL-5 and SK-MEL-28, and HCT-116. These results indicate that targeting RSK2 with natural compounds, such as kaempferol, might be a good strategy for chemopreventive or chemotherapeutic application. [Cancer Res 2009;69(10):4398–406]
Loss of Phosphatase and Tensin Homologue Deleted on Chromosome 10 Engages ErbB3 and Insulin-Like Growth Factor-I Receptor Signaling to Promote Antiestrogen Resistance in Breast Cancer
Authors: Miller Todd W. , Pérez-Torres Marianela , Narasanna Archana , Guix Marta , Stål Olle , Pérez-Tenorio Gizeh , Gonzalez-Angulo Ana M. , Hennessy Bryan T. , Mills Gordon B. , Kennedy J. Phillip , Lindsley Craig W. , Arteaga Carlos L.
Published: May 2009

Knockdown of the tumor suppressor phosphatase Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) with shRNA in three estrogen receptor (ER)-positive breast cancer cell lines resulted in increased phosphatidylinositol-3 kinase (PI3K) and AKT activities, resistance to tamoxifen and fulvestrant, and hormone-independent growth. PTEN knockdown induced the up-regulation of ER transcriptional activity in MCF-7 cells but decreased ER protein levels and transcriptional activity in T47D and MDA-361 cells. Tamoxifen and fulvestrant treatment inhibited estradiol-induced ER transcriptional activity in all shPTEN cell lines but did not abrogate the increased cell proliferation induced by PTEN knockdown. PTEN knockdown increased basal and ligand-induced activation of the insulin-like growth factor-I (IGF-I) and ErbB3 receptor tyrosine kinases, and prolonged the association of the p85 PI3K subunit with the IGF-I receptor (IGF-IR) effector insulin receptor substrate-1 and with ErbB3, implicating PTEN in the modulation of signaling upstream of PI3K. Consistent with these data, PTEN levels inversely correlated with levels of tyrosine-phosphorylated IGF-IR in tissue lysate arrays of primary breast cancers. Inhibition of IGF-IR and/or ErbB2-mediated activation of ErbB3 with tyrosine kinase inhibitors restored hormone dependence and the growth inhibitory effect of tamoxifen and fulvestrant on shPTEN cells, suggesting that cotargeting both ER and receptor tyrosine kinase pathways holds promise for the treatment of patients with ER+, PTEN-deficient breast cancers. [Cancer Res 2009;69(10):4192–201]
Endoplasmic Reticulum Stress Triggers XBP-1–Mediated Up-regulation of an EBV Oncoprotein in Nasopharyngeal Carcinoma
Authors: Hsiao Jenn-Ren , Chang Kung-Chao , Chen Chaio-Wei , Wu Shih-Yi , Su Ih-Jen , Hsu Mei-Chi , Jin Ying-Tai , Tsai Sen-Tien , Takada Kenzo , Chang Yao
Published: May 2009

Endoplasmic reticulum (ER) stress-activated unfolded protein response (UPR) plays multiple roles in cancer development, but its specific roles for virus-associated cancers have not been fully understood. It is still unknown whether ER stress/UPR occurs in and contributes to nasopharyngeal carcinoma (NPC), an epithelial malignancy closely associated with EBV. Here, we report that UPR proteins are frequently detected in NPC biopsies. In addition, we reveal that, in EBV-infected NPC cells, ER stress inducers up-regulate a potent EBV oncoprotein latent membrane protein 1 (LMP1), and the ER stress-induced LMP1 enhances production of interleukin-8. ER stress triggers LMP1 expression at a transcriptional level, activating a distal LMP1 promoter TR-L1. TR-L1 contains an ER stress-responsive element, which is targeted by an UPR protein XBP-1. Ectopic expression of XBP-1 induces LMP1 expression, and knockdown of XBP-1 blocks ER stress-triggered up-regulation of LMP1 in NPC cells. Furthermore, XBP-1 significantly correlates with LMP1 expression in NPC tumor biopsies. Therefore, this study not only provides a novel clue linking ER stress/UPR to EBV-associated NPC but also suggests that ER stress/UPR can promote virus-associated cancer in a unique way by driving expression of a viral oncogene. [Cancer Res 2009;69(10):4461–7]
Cell Cycle Regulation by MicroRNAs in Embryonic Stem Cells
Authors: Wang Yangming , Blelloch Robert
Published: May 2009

The cell cycle is tightly orchestrated during normal development. Embryonic stem (ES) cells have a unique cell cycle structure, in which the G1/S restriction is largely absent, enabling cells to rapidly move through the G1 phase and enter the S phase. This hastened cell cycle allows the early embryo to rapidly grow. Recent experiments suggest that small noncoding RNAs, the microRNAs (miRNAs), play a central role in achieving this unique cell cycle structure. The responsible miRNAs function by suppressing multiple inhibitors of the G1/S transition. Expression of these miRNAs drops dramatically as the ES cells differentiate and as the G1 phase extends. Some of the same miRNAs are overexpressed in cancers, in which they can promote tumor growth, suggesting common mechanisms of miRNA-regulated cell cycle control in ES cells and cancers. This review discusses these recent findings in the context of broader knowledge of cell cycle control in normal and abnormal development. [Cancer Res 2009;69(10):4093–6]
Molecular Mechanisms Underlying Effects of Epidermal Growth Factor Receptor Inhibition on Invasion, Proliferation, and Angiogenesis in Experimental Glioma
Authors: Guillamo Jean-Sébastien , de Boüard Sophie , Valable Samuel , Marteau Lena , Leuraud Pascal , Marie Yannick , Poupon Marie-France , Parienti Jean-Jacques , Raymond Eric , Peschanski Marc
Published: May 2009

Purpose: Epidermal growth factor receptor (EGFR) signal transduction pathways are implicated in malignant glioma aggressiveness and promote tumor cell invasion, proliferation, and angiogenesis. Nevertheless, response to EGFR tyrosine kinase inhibitor gefitinib (Iressa, ZD1839) has been disappointing in clinical trials. One potential explanation may come from the diversity of molecular alterations seen in gliomas. To validate that hypothesis, we have investigated responses to gefitinib on various tumor parameters in human malignant gliomas that exhibited different molecular alterations.

Experimental Design: We used a panel of six human malignant gliomas from established xenografts characterized for their genetic (EGFR, PTEN, TP53, and CDKN2A) and molecular (EGFR, PTEN, ERK, and Akt) alterations. Tumors were treated with gefitinib (1 or 10 μmol/L) for prolonged periods (8 or 16 days) in an organotypic brain slice model that allowed quantification of invasion, proliferation, and angiogenesis.

Results: In nontreated tumors, EGFR amplification was associated with profuse tumor cell invasion. After treatment, invasion was inhibited in tumors with EGFR amplification in a dose-dependent manner. Treatment had only antiproliferative effect in two of three tumors with EGFR amplification. Tumors with PTEN loss were resistant to treatment. We did not observe shrinkage of the tumors after treatment. None of the tumors had mutations of the EGFR kinase domain. Gefitinib had similar antiangiogenic effect in all of the tumors.

Conclusions: Gefitinib reduces cell invasion in EGFR amplified tumors. PTEN loss of expression seems to be a determinant of resistance. Interestingly, inhibition of angiogenesis by gefitinib seems independent on the EGFR genetic status of the tumors.
Prediction of Prostate Cancer Recurrence Using Magnetic Resonance Imaging and Molecular Profiles
Authors: Shukla-Dave Amita , Hricak Hedvig , Ishill Nicole , Moskowitz Chaya S. , Drobnjak Marija , Reuter Victor E. , Zakian Kristen L. , Scardino Peter T. , Cordon-Cardo Carlos
Published: May 2009

Purpose: To evaluate whether pretreatment magnetic resonance imaging (MRI)/MR spectroscopic imaging (MRSI) findings and molecular markers in surgical specimens correlate with each other and with pretreatment clinical variables (biopsy Gleason score, clinical stage, and prostate-specific antigen level) and whether they contribute incremental value in predicting prostate cancer recurrence.

Experimental Design: Eighty-eight prostate cancer patients underwent MRI/MRSI before radical prostatectomy; imaging findings were scored on a scale of 1 to 7 (no tumor seen—lymph node metastasis). Ki-67, phospho-Akt, and androgen receptor expression in surgical specimens were assessed by immunohistochemistry. To examine correlations between markers and imaging scores, Spearman's correlation was used. To test whether markers and imaging scores differed by clinical stage or Gleason score, Wilcoxon's rank sum test was used. To examine time to recurrence, the methods of Kaplan-Meier were used. Cox proportional hazards models were built and their concordance indices (C-indices) were calculated to evaluate prediction of recurrence.

Results: All markers correlated moderately strongly with MRI/MRSI score (all correlation coefficients >0.5). Markers and MRI/MRSI score were strongly associated with clinical stage and biopsy Gleason score (P < 0.01 for all). At last follow-up, 27 patients had recurrence. C-indices for MRI/MRSI score and all markers were associated with time to recurrence and ranged from 0.78 to 0.89. A Cox model combining all clinical predictors had a C-index of 0.89; the C-index increased to 0.95 when MRI/MRSI score was added and to 0.97 when markers were also added.

Conclusions: MRI/MRSI findings and molecular markers correlated well with each other and contributed incremental value to clinical variables in predicting prostate cancer recurrence.
Antibodies targeting hepatoma-derived growth factor as a novel strategy in treating lung cancer
Authors: Ren Hening , Chu Zuoming , Mao Li
Published: May 2009

Hepatoma-derived growth factor (HDGF) is overexpressed in lung cancer and the overexpression correlates with aggressive biological behaviors and poor clinical outcomes. We developed anti-HDGF monoclonal antibodies and tested their antitumor activity in lung cancer xenograft models. We also determined biological effects in tumors treated with the antibody alone or in combination with bevacizumab/avastin (an anti-vascular endothelial growth factor antibody) and/or gemcitabine (a chemotherapeutic agent). We found the anti-HDGF was effective to inhibit tumor growth in non-small cell lung cancer xenograft models. In the A549 model, compared with control IgG, tumor growth was substantially inhibited in animals treated with anti-HDGF antibodies, particularly HDGF-C1 (P = 0.002) and HDGF-H3 (P = 0.005). When HDGF-H3 was combined with either bevacizumab or gemcitabine, we observed enhanced tumor growth inhibition, particularly when the three agents were used together. HDGF-H3-treated tumors exhibited significant reduction of microvessel density with a pattern distinctive from the microvessel reduction pattern observed in bevacizumab-treated tumors. HDGF-H3-treated but not bevacizumab-treated tumors also showed a significant increase of apoptosis. Interestingly, many of the apoptotic cells in HDGF-H3-treated tumors are stroma cells, suggesting that the mechanism of the antitumor activity is, at least in part, through disrupting formation of tumor-stroma structures. Our results show that HDGF is a novel therapeutic target for lung cancer and can be effectively targeted by an antibody-based approach.[Mol Cancer Ther 2009;8(5):1106–12]
The antitumoral effect of Paris Saponin I associated with the induction of apoptosis through the mitochondrial pathway
Authors: Xiao Xue , Bai Peng , Bui Nguyen Tri M. , Xiao Jianguo , Liu Shanling , Yang Gong , Hu Lina , Chen Xinlian , Zhang Xuemei , Liu Jinsong , Wang He
Published: May 2009

Rhizoma Paridis, a traditional Chinese medicine, has shown promise in cancer prevention and therapy. In the present study, we isolated Paris Saponin I (PSI), an active component of Rhizoma paridis, and evaluated its effects on a panel of human cell lines and in a mouse model of human ovarian cancer to explore the mechanisms of its activity. PSI had more potent and selective cytotoxic effects on tumor cell lines than etoposide had, promoting dramatic G2-M phase arrest and apoptosis in SKOV3 cells in a time- and dose-dependent manner. Furthermore, PSI treatment increased levels of Bax, cytochrome c, activated caspase-3, active caspase-9, and cleaved poly(ADP-ribose) polymerase and decreased both Bcl-2 expression levels and extracellular signal–regulated kinase-1/2 activity. We also assessed the antitumor efficacy of i.p. and p.o. PSI administration in mice bearing SKOV3 tumors; both significantly inhibited the growth of SKOV3 cells in a subcutaneous xenograft mouse model (by 66% and 52%, respectively). These results indicate that PSI mediates its effects via mitochondrial apoptosis, mitogen-activated protein kinase pathways, and G2-M cell cycle arrest. Most important, the efficacy of PSI in xenografts when administered p.o. or i.p. suggests its clinical potential. Thus, PSI is a potent antitumor compound and should be developed as a natural agent for cancer therapy.[Mol Cancer Ther 2009;8(5):1179–88]
MicroRNA-200c mitigates invasiveness and restores sensitivity to microtubule-targeting chemotherapeutic agents
Authors: Cochrane Dawn R. , Spoelstra Nicole S. , Howe Erin N. , Nordeen Steven K. , Richer Jennifer K.
Published: May 2009

The transcription factor ZEB1 is normally not expressed in epithelial cells. When inappropriately expressed in carcinomas, ZEB1 initiates epithelial to mesenchymal transition due to its ability to repress E-cadherin and other genes involved in polarity. Recently, ZEB1 and ZEB2 have been identified as direct targets of the microRNA-200c family. We find that miR-200c levels are high in well-differentiated endometrial, breast, and ovarian cancer cell lines, but extremely low in poorly differentiated cancer cells. Low or absent miR-200c results in aberrant expression of ZEB1 and consequent repression of E-cadherin. Reinstatement of miR-200c to such cells restores E-cadherin and dramatically reduces migration and invasion. Microarray profiling reveals that in addition to ZEB1 and ZEB2, other mesenchymal genes (such as FN1, NTRK2, and QKI), which are also predicted direct targets of miR-200c, are indeed inhibited by addition of exogenous miR-200c. One such gene, class III β-tubulin (TUBB3), which encodes a tubulin isotype normally found only in neuronal cells, is a direct target of miR-200c. This finding is of particular significance because we show that restoration of miR-200c increases sensitivity to microtubule-targeting agents by 85%. Because expression of TUBB3 is a common mechanism of resistance to microtubule-binding chemotherapeutic agents in many types of solid tumors, the ability of miR-200c to restore chemosensitivity to such agents may be explained by its ability to reduce TUBB3. Because miR-200c is crucial for maintenance of epithelial identity, behavior, and sensitivity to chemotherapy, we propose that it warrants further investigation as a therapeutic strategy for aggressive, drug-resistant cancers. [Mol Cancer Ther 2009;8(5):OF1–12]
Synthesis and characterization of a high-affinity αvβ6-specific ligand for in vitro and in vivo applications
Authors: Li Shunzi , McGuire Michael J. , Lin Mai , Liu Ying-Horng , Oyama Tsukasa , Sun Xiankai , Brown Kathlynn C.
Published: May 2009

The αvβ6 integrin is an attractive therapeutic target for several cancers due to its role in metastasis and its negligible expression in normal tissues. We previously identified a peptide from a phage-displayed peptide library that binds specifically to αvβ6. The tetrameric version of the peptide has higher affinity for its cellular targets than the corresponding monomers. However, the inefficient synthesis limits its clinical potential. We report here a convergent synthesis producing the tetrameric peptide in high yield and purity. The ease of the synthesis allows for rapid optimization of the peptide. We have optimized this αvβ6 integrin–binding peptide, determining the minimal binding domain and valency. Importantly, the half-maximal binding affinity of the optimal peptide for its target cell is in the 40 to 60 pmol/L range, rivaling the affinity of commonly used antibody-targeting reagents. This peptide mediates cell-specific uptake, is functional in diagnostic formats, is stable in sera, and can home to a tumor in an animal. We anticipate that this high-affinity ligand for αvβ6 will find clinical use as a diagnostic and therapeutic reagent. [Mol Cancer Ther 2009;8(5):1239–49]
Secreted Interleukin-1α Induces a Metastatic Phenotype in Pancreatic Cancer by Sustaining a Constitutive Activation of Nuclear Factor-κB
Authors: Melisi Davide , Niu Jiangong , Chang Zhe , Xia Qianghua , Peng Bailu , Ishiyama Satoshi , Evans Douglas B. , Chiao Paul J.
Published: May 2009

Transcription factor nuclear factor-κB (NF-κB) is constitutively activated in most pancreatic cancer tissues and cell lines but not in normal pancreas nor in immortalized/nontumorigenic human pancreatic ductal epithelial cells. Inhibition of constitutive NF-κB activation in pancreatic cancer cell lines suppresses tumorigenesis and tumor metastasis. Recently, we identified autocrine secretion of proinflammatory cytokine interleukin (IL)-1α as the mechanism of constitutive NF-κB activation in metastatic pancreatic cancer cell lines. However, the role of IL-1α in determining the metastatic potential of pancreatic tumor remains to be further investigated. In the current study, we stably expressed IL-1α in the nonmetastatic, IL-1α–negative MiaPaCa-2 cell lines. Our results showed that the secretion of IL-1α in MiaPaCa-2 cells constitutively activated NF-κB and increased the expression of NF-κB downstream genes involved in the different steps of the metastatic cascade, such as urokinase-type plasminogen activator, vascular endothelial growth factor, and IL-8. MiaPaCa-2/IL-1α cells showed an enhanced cell invasion in vitro compared with parental MiaPaCa-2 cells and induced liver metastasis in an orthotopic mouse model. The metastatic phenotype induced by IL-1α was inhibited by the expression of phosphorylation-defective IκB (IκB S32, 36A), which blocked NF-κB activation. Consistently, silencing the expression of IL-1α by short hairpin RNA in the highly metastatic L3.6pl pancreatic cancer cells completely suppressed their metastatic spread. In summary, these findings showed that IL-1α plays key roles in pancreatic cancer metastatic behavior through the constitutive activation of NF-κB. Our findings further support the possible link between inflammation and cancer and suggest that IL-1α may be a potential therapeutic target for treating pancreatic adenocarcinoma. (Mol Cancer Res 2009;7(5):624–33)
The Estrogen Receptor α Pathway Induces OncogenicWip1Phosphatase Gene Expression
Authors: Han Hye-Sook , Yu Eunsil , Song Ji-Young , Park Ji-Young , Jang Se Jin , Choi Jene
Published: May 2009

Wild-type p53-induced phosphatase (Wip1) is a serine/threonine phosphatase induced by DNA-damaging agents. This enzyme dephosphorylates several cell cycle regulating proteins, including p53, p38 mitogen-activated protein kinase, Chk1, and Chk2, resulting in negative feedback regulation of p38-p53 signaling after damage repair. Moreover, the Wip1 gene may be amplified or overexpressed, especially in hormone-regulated organs, and Wip1 gene amplification has been correlated with poor prognosis in hormone-related malignancies, including ovarian cancers. We therefore investigated the link between estrogen signaling and Wip1 expression. We identified seven putative estrogen response elements within 3 kb of the Wip1 promoter. We also found that estradiol (E2) treatment produced a 3-fold increase in endogenous Wip1 mRNA and protein expression in MCF7 cells. Direct binding of estrogen receptor (ER)α to the Wip1 promoter after E2 treatment was confirmed by a chromatin immunoprecipitation assay using ERα antibody and an electrophoretic mobility shift assay. Wip1 overexpression induced by adenovirus and E2 facilitated the proliferation of serum-starved ZR-75-1 cells, with cell proliferation induced by overexpressed Wip1 ∼25% higher than that induced by E2. Wip1 phosphatase activity was essential for cell cycle progression. Wip1 stimulated the transcriptional activity of its own promoter through E2-ERα signaling. In addition, Wip1 overexpression induced Rb phosphorylation during cancer cell proliferation. These results indicate that Wip1 up-regulation is important in the pathogenesis of p53+ and ER+ breast cancer through the inactivation of p53 by dephosphorylation and the amplification of subsequent estrogenic effects through the E2-ERα-Wip1 pathway.(Mol Cancer Res 2009;7(5):713–23)
Antifolate Activity of Pyrimethamine Enhances Temozolomide-Induced Cytotoxicity in Melanoma Cells
Authors: Chen Ming , Osman Iman , Orlow Seth J.
Published: May 2009

Most metastatic melanoma patients fail to respond to available therapy, underscoring the need to develop more effective treatments. We screened 2,000 compounds from the Spectrum Library in human melanoma cell lines to identify compounds that enhanced the cytotoxic effect of temozolomide, a drug used to treat metastatic melanoma.

Screening was done with the temozolomide-resistant melanoma cell line SK-MEL-19, and six compounds were identified that had little or no inherent cytotoxicity but significantly enhanced growth-inhibition by temozolomide. These compounds were tested in five additional melanoma cell lines. Cell proliferation and death assays were used to compare the efficacy of single agent temozolomide versus combination treatments. Effects of combination treatment on levels of DNA double-strand breaks, the DNA repair protein O6-methylguanine-DNA-methyltransferase, apoptosis [measured by cleaved caspase-3 and poly(ADP-ribose) polymerase], and cell cycle were examined. Pyrimethamine, an antiparasitic, sensitized melanoma cells to temozolomide. Temozolomide combined with Pyrimethamine synergistically inhibited cell proliferation in melanoma cells with combination index values of 0.7 or less. In addition, combination treatment induced cell cycle arrest and increased both DNA damage and apoptosis. The increase in cell death due to combination treatment was rescued by leucovorin. Other folate antagonists were also effective enhancers of temozolomide-induced cytotoxicity, and the effects of antifolates were also evident in gliomas. Our screening approach led to the identification of Pyrimethamine, an orally available drug that efficiently crosses the blood-brain barrier, as a potent enhancer of the efficacy of temozolomide as an antineoplastic agent via inhibition of folate metabolism. (Mol Cancer Res 2009;7(5):703–12)
Role of the Protein Tyrosine Kinase Syk in Regulating Cell-Cell Adhesion and Motility in Breast Cancer Cells
Authors: Zhang Xiaoying , Shrikhande Ulka , Alicie Bethany M. , Zhou Qing , Geahlen Robert L.
Published: May 2009

The expression of the Syk protein tyrosine kinase in breast cancer cells is inversely correlated with invasive growth and metastasis. The expression of Syk inhibits cell motility while supporting the formation of cell clusters by enhancing cell-cell contacts and promoting the redistribution of the adhesion proteins cortactin and vinculin to these contacts. Syk associates physically with cortactin and catalyzes its phosphorylation on tyrosine. The clustering of integrins leads to the phosphorylation of Syk and of numerous cellular proteins in a manner dependent on the activity of the kinase and on the presence of tyrosine 342 located in the linker B region. The ability of Syk to participate in integrin-mediated protein tyrosine phosphorylation correlates well with its ability to inhibit cell motility. (Mol Cancer Res 2009;7(5):634–44)
Activator Protein-1 Has an Essential Role in Pancreatic Cancer Cells and Is Regulated by a Novel Akt-Mediated Mechanism
Authors: Shin Sonyo , Asano Takayuki , Yao Yixin , Zhang Ronghua , Claret Francois-Xavier , Korc Murray , Sabapathy Kanaga , Menter David G. , Abbruzzese James L. , Reddy Shrikanth A.G.
Published: May 2009

Activator protein-1 (AP-1) regulates the expression of several genes involved in human tumorigenesis. However, there is little known about this transcription factor in pancreatic ductal adenocarcinoma. We recently found high levels of AP-1-binding activities and multiple AP-1/DNA complexes containing c-Jun, JunD, Fra1, and Fra2 in pancreatic cancer cells. Transient transfection assays indicated that AP-1 was functional and capable of transactivating its gene targets. Furthermore, a c-Jun transactivation mutant inhibited anchorage-dependent and anchorage-independent proliferation, suggesting that AP-1 had an essential role in pancreatic cancer cells. Our study also uncovered a novel mechanism by which protein kinase Akt controls c-Jun activity in pancreatic cancer cells. Indeed, distinct from its known ability to induce c-fos and fra1 and to stabilize c-Jun, Akt appeared to directly regulate the transcriptional activity of c-Jun independently of the phosphorylation sites targeted by c-Jun NH2-terminal kinase (Ser63/Ser73) and glycogen synthase kinase-3 (Thr239). Our data also suggest that growth factors might use this Akt-regulated mechanism to potently induce c-Jun targets such as cyclin D1. Collectively, our findings indicate that AP-1 has an important function in pancreatic cancer cells and provide evidence for a previously unknown Akt-mediated mechanism of c-Jun activation. (Mol Cancer Res 2009;7(5):745–54)
GFAP-Cre–Mediated Activation of Oncogenic K-ras Results in Expansion of the Subventricular Zone and Infiltrating Glioma
Authors: Abel Ty W. , Clark Cara , Bierie Brian , Chytil Anna , Aakre Mary , Gorska Agnieszka , Moses Harold L.
Published: May 2009

A subset of neoplastic cells within human high-grade gliomas has features associated with stem cells. These cells may sustain glioma growth, and their stem-like properties may confer resistance to standard glioma treatments. Whether glioma stem cells derive from indigenous neural stem cells (NSC), or from tumor cells that have reacquired stem cell-like properties, is unknown. However, signaling pathways that are tightly regulated and central to NSC biology, including the Ras/Raf/Erk pathway, are hyperactive and pathogenic in gliomagenesis. Furthermore, data in animal models suggests that, in some cases, tumors are initiated in the subventricular zone (SVZ), a stem/progenitor cell niche in the mature brain. We activated oncogenic K-ras in mouse glioneuronal precursor cells and adult SVZ cells using GFAP-Cre. GFAP-Cre+/K-rasG12D mice showed a marked expansion of glial fibriallary acidic protein (GFAP)- and TUJ1–expressing cell populations in the SVZ. In addition, mice developed intermediate grade, infiltrating glioma with 100% penetrance. Tumors were consistently located in the amygdalohippocampal region and nearby cortex, often in association with the lateral ventricle and expanded SVZ. Tumor cells expressed markers associated with neural progenitor cells, including Olig2, Bmi-1, and PDGFR-α. These data suggest that infiltrating tumor cells may arise from NSC transformed by activation of oncogenic K-ras in vivo. (Mol Cancer Res 2009;7(5):645–53)
Risk of Recurrent Stroke, Other Vascular Events and Dementia after Transient Ischaemic Attack and Stroke
Authors: Pendlebury Sarah T. , Rothwell Peter M.
Published: May 2009

The early risk of recurrence after transient ischaemic attack (TIA) or minor stroke is high, ranging from 11% at 7 days in population-based studies, where patients are seen non-urgently, to 3% at 7 days in studies where patients are seen urgently in specialist services. In long-term (up to 10 years) studies of vascular risks after TIA and stroke, the risk of stroke is highest early after the event, and then falls, whereas the risk of coronary events is constant over the follow-up period at around 2% per year. In contrast to the early risk after TIA and stroke, the long-term risks are more dependent on the underlying vascular risk factors than the characteristics of the event itself. Stroke is also associated with an increased risk of dementia. Prevalence of post-stroke dementia varies between studies but is around 28% at 3 months in hospital-based studies where pre-stroke dementia was not excluded and 18% in hospital-based studies excluding pre-stroke dementia. Risk factors for post-stroke dementia include low education, prior or recurrent stroke, and older age. In conclusion, available data suggest that the risk of recurrent vascular events is considerable after TIA and stroke, even in the longer term, and that there is also a high risk of dementia after stroke. However, more studies are required to determine medium- and long-term outcomes in the current era of aggressive secondary preventive therapy.
Infliximab Rescue Therapy after Cyclosporin Failure in Steroid-Refractory Ulcerative Colitis
Authors: Mañosa Míriam , López San Román Antonio , Garcia-Planella Esther , Bastida Guillermo , Hinojosa Joaquín , Gonzalez-Lama Yago , Masnou Helena , Domènech Eugeni
Published: May 2009

Background: Cyclosporin (CsA) and infliximab (IFX) have proven efficacy in avoiding colectomy in patients with steroid-refractory ulcerative colitis (UC). Aim: To assess the clinical outcome of patients treated with IFX after CsA failure for acute steroid-refractory flares of UC. Methods: Medical records of patients with a steroid-refractory UC flare who did not respond to CsA or relapsed soon after hospital discharge, and who followed rescue therapy with IFX, were reviewed retrospectively. Results: Sixteen patients were included, 69% with extensive UC. Thirteen patients had moderate-to-severe disease activity at the time IFX was started. Median time between CsA discontinuation and the first IFX infusion was 19 days. Thirteen patients completed an induction regimen, and 6 of them followed scheduled maintenance treatment with IFX. After a median time of follow-up from the first IFX infusion of 195 days, 6 patients (37.5%) required colectomy. Median time for colectomy was 47 days. There were no deaths or malignancies, and only one septic complication was recorded. Conclusions: IFX rescue therapy might avoid short-term colectomy in a proportion of steroid-refractory UC patients who do not respond to CsA, but systematic use of sequential rescue therapy is not recommended until more data about its safety profile is available.
Prospective, Observational, Cross-Sectional Study of Intestinal Infections among Acutely Active Inflammatory Bowel Disease Patients
Authors: Navarro-Llavat Mercè , Domènech Eugeni , Bernal Isabel , Sánchez-Delgado Jordi , Manterola José M. , Garcia-Planella Esther , Mañosa Míriam , Cabré Eduard , Gassull Miquel A.
Published: May 2009

Background: Intestinal infections have been claimed to precipitate or aggravate flares of inflammatory bowel disease (IBD). The reported incidence of such infections among IBD patients varies between 9 and 13%, but only a few prospective studies have been conducted. Aims: To evaluate the incidence of intestinal infections by enteropathogens in patients with active IBD, their impact on clinical outcome, and to identify associated risk factors. Patients and Methods: Consecutive patients admitted because of a relapse or suspected onset of IBD were prospectively included. At admittance, stool samples for culture, examination for intestinal parasites, and cytotoxin assay for Clostridium difficile were collected. Baseline clinical characteristics, potential risk factors for gastrointestinal infections, and clinical outcome were recorded. Results: Ninety-nine episodes were included. Six intestinal infections were diagnosed in 6 patients (5 ulcerative colitis, 1 ileocolonic Crohn’s disease), Campylobacter jejuni being the most frequent isolated microbe (n = 5). None of the patients with intestinal infection needed surgery, but two of them required second-line therapies. Conclusions: Gastrointestinal infections among IBD patients do not exceed 10% and occur mostly in patients with extensive involvement of the colon. Infection by enteropathogenic bacteria does not appear to be associated with a poorer clinical outcome of the IBD flare.
Update on Slow Aging and Negligible Senescence – A Mini-Review
Authors: Finch Caleb E.
Published: May 2009

This review updates developments of the concept of negligible senescence, proposed in Longevity, Senescence, and the Genome in 1990, with new information for turtles, rockfish, and the naked mole-rat. However, centenarians certainly do not show negligible senescence.
Expression Levels of TLRs Involved in Viral Recognition in PBMCs from HIV-1-Infected Patients Failing Antiretroviral Therapy
Authors: Scagnolari Carolina , Selvaggi Carla , Chiavuzzo Luisa , Carbone Teresa , Zaffiri Lorenzo , d’Ettorre Gabriella , Girardi Enrico , Turriziani Ombretta , Vullo Vincenzo , Antonelli Guido
Published: May 2009

Objective: The aim of this study was to evaluate whether gene expression of Toll-like receptor (TLR)-3, TLR4, TLR7 and TLR9 was impaired in patients with chronic HIV-1 infection who were failing to respond to antiretroviral therapy. Methods: Transcripts encoding TLRs were assayed by quantitative real time RT-PCR on peripheral blood mononuclear cells derived from patients with HIV-1 infection who were responding or not responding to antiretroviral therapy and healthy control subjects. Results: Chronic HIV-1-infected patients who failed to respond to therapy showed reduced expression of TLRs 3, 4 and 9, together with increased expression of TLR7, as compared to healthy subjects. Moreover, a trend towards a higher expression of TLR3 and TLR9 was observed in responder patients compared with non-responders. In addition, we found lower levels of TRLs 3, 7 and 9 in patients with high levels of HIV-1 RNA compared to those with lower levels of viremia. Conclusions: These findings demonstrate that in chronic HIV-1-positive patients who were failing to respond to the therapy, there were substantial changes in TLRs expression. This is likely to be an important determinant of the clinical course of HIV-1 infection.
N-Acetylcysteine Improves Arterial Vascular Reactivity in Patients with Chronic Kidney Disease
Authors: Wittstock Antje , Burkert Magdalena , Zidek Walter , Tepel Martin , Scholze Alexandra
Published: May 2009

Background: Patients with stage 5 chronic kidney disease show increased cardiovascular morbidity and mortality that are partly related to impaired arterial vascular reactivity. We investigated whether intravenous administration of the antioxidant acetylcysteine improves arterial vascular reactivity in these patients. Methods: Arterial vascular reactivity was determined during reactive hyperemia by photoplethysmography of digital pulse waves in a randomized, prospective, placebo-controlled cross-over study of 24 patients with stage 5 chronic kidney disease with and without infusion of acetylcysteine during hemodialysis. Acetylcysteine (5 g in 5% glucose in a final volume of 50 ml) was continuously administered intravenously during one hemodialysis session. Results: In the absence of acetylcysteine, the reflective index was 38.5 ± 9.4 (mean ± SD; n = 24) at baseline and 33.8 ± 9.9 during reactive hyperemia, immediately after the hemodialysis session; thus there was no significant vasodilatation (p > 0.05), indicating impaired arterial vascular reactivity in these patients. However, when the hemodialysis session in the same patients was performed in the presence of acetylcysteine, the reflective index significantly decreased from 37.9 ± 8.6 at baseline to 30.2 ± 10.3 during reactive hyperemia (n = 24; p < 0.01). Conclusion: The present study shows that intravenous administration of acetylcysteine during hemodialysis significantly improves arterial vascular reactivity during reactive hyperemia.
Allergy to Carmine Red (E120) Is Not Dependent on Concurrent Mite Allergy
Authors: Liippo Jussi , Lammintausta Kaija
Published: May 2009

Background: Positive skin prick test (SPT) reactions to carmine red (E120) have been reported to occur concurrently with reactions to mites. The relationships between positive SPT reactions to carmine, carmine allergy and concurrent mite reactions are unknown. The aim of this study was to analyse the prevalence of carmine sensitization and its clinical importance among patients with suspected allergy to food additives. Methods: The occurrence of positive SPT reactions to mites was studied in 6,464 patients: 3,164 were tested with carmine and 2,837 with shrimp. Carmine ingestion-associated symptoms were registered at the time of testing. Patients with positive SPT to carmine received a follow-up questionnaire on their symptoms 1–5 years later. Results: Positive SPT reactions to carmine were seen in 94 patients (3.0%) of whom 74% also had positive SPT reactions to mites and 22% to shrimp. Carmine ingestion-associated symptoms were not dependent on concurrent mite reactivity in 39/94 (42%) patients. Conclusions: Carmine sensitization without sensitization to mites is seen in one fourth of the patients. Allergic reactions to carmine are not dependent on concurrent reactivity to mites.
The Physics of Hydrocephalus
Authors: Penn Richard D. , Linninger Andreas
Published: May 2009

This article reviews our previous work on the dynamics of the intracranial cavity and presents new clinically relevant results about hydrocephalus that can be gained from this approach. Simulations based on fluid dynamics and poroelasticity theory are used to predict CSF flow, pressures and brain tissue movement in normal subjects. Communicating hydrocephalus is created in the model by decreasing CSF absorption. The predictions are shown to reflect dynamics demonstrated by structural MRI and cine-MRI studies of normal subjects and hydrocephalus patients. The simulations are then used to explain unilateral hydrocephalus and how hydrocephalus could occur without CSF pulsations. The simulations also predict the known pressure/volume relationships seen on bolus infusions of CSF, and the small transmural pressure gradients observed in animal experiments and in patients with hydrocephalus. The complications and poor performance of shunts based on pressure-sensitive valves are explained and a system of feedback control is suggested as a solution.
Extraoperative Functional Mapping and Staged Resection of Supratentorial Tumors near Eloquent Cortex in Children
Authors: Bollo Robert J. , Carlson Chad , Schevon Catherine , Wisoff Jeffrey H. , Devinsky Orrin , Weiner Howard L.
Published: May 2009

We present our technique for extraoperative functional mapping in awake children with supratentorial tumors near eloquent cortex. This technique may help optimize tumor resection and/or the functional outcome, especially when an awake craniotomy is not possible or in the setting of coincident seizures. After subdural electrode implantation, extraoperative functional mapping and seizure focus mapping were performed, followed by staged tumor resection. Gross total resection was achieved in 6 patients and subtotal resection in 2. No complications due to electrode placement or invasive monitoring were observed. Staged resection of pediatric brain tumors near the eloquent cortex appears safe, allows functional mapping in awake patients, and may assist in decisions between maximal tumor resection and optimal functional outcome.
Conservative Management of Acute Epidural Hematoma in a Pediatric Age Group
Authors: Jamous Mohammad A. , Abdel Aziz Hani , Al Kaisy Farouk , Eloqayli Haytham , Azab Mohammed , Al-Jarrah Muhammed
Published: May 2009

Objective: Craniotomy and evacuation is the standard treatment of acute epidural hematoma (EDH). Here, the authors report their experience in nonoperative management of acute EDH in children with mild head injury. Methods: The authors retrospectively reviewed charts of patients with conservatively treated EDH at the Department of Neurosurgery, King Abdulla University Hospital, Irbid, Jordan, between August 2003 and October 2007. All patients had a Glasgow Coma Scale score of 14 or 15, and an initial computerized tomography (CT) scan demonstrating an EDH with or without skull fractures. Follow-up included neurological examination and brain CT. Results: Six children (3 boys, 3 girls) with acute EDH were successfully managed at our department without surgical intervention. The Glasgow Outcome Scale score of all patients was 5, with no posttraumatic sequelae. Follow-up brain CT showed complete resolution of the EDH within 2–3 months. Conclusions: Our results demonstrated that pediatric EDH can be managed nonoperatively. The pronounced increase in the number of CT examinations for patients with head injuries has resulted in a greater proportion of EDH detected in conscious patients. We recommend such treatment be performed in specialized pediatric neurosurgical centers under close neurological observation.