bluuebunny/crossref_metadata_2025 huggingface dataset:
Baroreflex responsiveness during ventilatory acclimatization in humans
Authors: Hunt Brian E. , Tamisier Renaud , Gilmartin Geoffrey S. , Curley Mathew , Anand Amit , Weiss J. Woodrow
Published: August 2008

We tested the hypothesis that the decline in muscle sympathetic activity during and after 8 h of poikilocapnic hypoxia (Hx) was associated with a greater sympathetic baroreflex-mediated responsiveness. In 10 healthy men and women ( n = 2), we measured beat-to-beat blood pressure (Portapres), carotid artery distension (ultrasonography), heart period, and muscle sympathetic nerve activity (SNA; microneurography) during two baroreflex perturbations using the modified Oxford technique before, during, and after 8 h of hypoxia (84% arterial oxygen saturation). The integrated baroreflex response [change of SNA (ΔSNA)/change of diastolic blood pressure (ΔDBP)], mechanical (Δdiastolic diameter/ΔDBP), and neural (ΔSNA/Δdiastolic diameter) components were estimated at each time point. Sympathetic baroreflex responsiveness declined throughout the hypoxic exposure and further declined upon return to normoxia [pre-Hx, −8.3 ± 1.2; 1-h Hx, −7.2 ± 1.0; 7-h Hx, −4.9 ± 1.0; and post-Hx: −4.1 ± 0.9 arbitrary integrated units (AIU)·min−1·mmHg−1; P < 0.05 vs. previous time point for 1-h, 7-h, and post-Hx values]. This blunting of baroreflex-mediated efferent outflow was not due to a change in the mechanical transduction of arterial pressure into barosensory stretch. Rather, the neural component declined in a similar pattern to that of the integrated reflex response (pre-Hx, −2.70 ± 0.53; 1-h Hx, −2.59 ± 0.53; 7-h Hx, −1.60 ± 0.34; and post-Hx, −1.34 ± 0.27 AIU·min−1·μm−1; P < 0.05 vs. pre-Hx for 7-h and post-Hx values). Thus it does not appear as if enhanced baroreflex function is primarily responsible for the reduced muscle SNA observed during intermediate duration hypoxia. However, the central transduction of baroreceptor afferent neural activity into efferent neural activity appears to be reduced during the initial stages of peripheral chemoreceptor acclimatization.
Comparison of electrical and magnetic stimulations to assess quadriceps muscle function
Authors: Verges Samuel , Maffiuletti Nicola A. , Kerherve Hugo , Decorte Nicolas , Wuyam Bernard , Millet Guillaume Y.
Published: August 2008

This study aimed to 1) compare electrical and magnetic stimulations for quadriceps muscle function assessment, and 2) ascertain whether the ratios of the second twitch elicited by supramaximal electrical and magnetic femoral nerve stimulation at 10 and 100 Hz (T210:100) and the total twitch force elicited by the same types of stimulations (Fpaired10:100) are equivalent to the standard low- to high-frequency force ratio associated with submaximal electrical tetanic stimulations (Ftet10:100). Quadriceps force and vastus lateralis EMG were recorded at rest ( n = 21 subjects), immediately after, and 30 min after a 30-min downhill run ( n = 10) when 1) supramaximal electrical nerve stimulation (ENS), 2) magnetic nerve stimulation (MNS) and 3) submaximal electrical muscle stimulation (EMS) were delivered in random order at 1 (single stimulation), 10, and 100 Hz (paired stimulations). Ten- and 100-Hz 500-ms tetani were also evoked with EMS to determine Ftet10:100. Before exercise, contractile properties with single and paired stimulations were similar for ENS and MNS (all intraclass correlation coefficients k > 0.90), but smaller for EMS ( P < 0.001). M-wave characteristics were also similar for ENS and MNS (all k > 0.90). After exercise, changes in all parameters did not differ between methods. With fatigue, the changes in Ftet10:100were inconsistently correlated with the changes in T210:100( r2= 0.24–0.73, P = 0.002–0.15) but better correlated with the changes in Fpaired10:100(immediately after exercise: r2= 0.80–0.83, P < 0.001; 30 min after exercise: r2= 0.46–0.82, P = 0.001–0.03). We conclude that ENS and MNS provide similar quadriceps muscle function assessment, while Fpaired10:100is a better index than T210:100of low- to high-frequency fatigue of the quadriceps in vivo.
Carbonic anhydrase III and four-and-a-half LIM protein 1 are preferentially oxidized with muscle unloading
Authors: Chen Chiao-nan , Ferrington Deborah A. , Thompson LaDora V.
Published: August 2008

The identities of proteins that show disuse-related changes in the content of oxidative modification are unknown. Furthermore, it is unknown whether the global accumulation of oxidized proteins is greater in aged animals with muscle disuse. The purposes of this study are 1) to identify the exact proteins that show disuse-related changes in oxidation levels and 2) to test the hypothesis that the global accumulation of oxidized proteins with muscle disuse would be greater in aged animals. Adult and old rats were randomized into four groups: weight bearing and 3, 7, or 14 days of hindlimb unloading. Soleus muscles were harvested to investigate the protein oxidation with unloading. Slot blot, SDS-PAGE, and Western blot analyses were used to detect the accumulation of 4-hydroxy-2-nonenol (HNE)- and nitrotyrosine (NT)-modified proteins. Matrix-assisted laser desorption ionization-time of flight and tandem mass spectroscopy were used to identify modified proteins. We found that global HNE- and NT-modified proteins accumulated significantly with aging but not with muscle unloading. Two HNE and NT target proteins, four-and-a-half LIM protein 1 (FHL1) and carbonic anhydrase III (CAIII), showed changes in the oxidation levels with muscle unloading. The changes in the oxidation levels happened to adult rats but not old rats. However, old rats had higher baseline levels of HNE-modified FHL1. In summary, the data suggest that the muscle unloading-related changes of protein oxidation are more significant in specific proteins and that the changes are age related.
PIK3CA Mutations and Copy Number Gains in Human Lung Cancers
Authors: Yamamoto Hiromasa , Shigematsu Hisayuki , Nomura Masaharu , Lockwood William W. , Sato Mitsuo , Okumura Naoki , Soh Junichi , Suzuki Makoto , Wistuba Ignacio I. , Fong Kwun M. , Lee Huei , Toyooka Shinichi , Date Hiroshi , Lam Wan L. , Minna John D. , Gazdar Adi F.
Published: August 2008

We investigated the frequency and function of mutations and increased copy number of the PIK3CA gene in lung cancers. PIK3CA mutations are one of the most common gene changes present in human cancers. We analyzed the mutational status of exons 9 and 20 and gene copy number of PIK3CA using 86 non–small cell lung cancer (NSCLC) cell lines, 43 small cell lung cancer (SCLC) cell lines, 3 extrapulmonary small cell cancer (ExPuSC) cell lines, and 691 resected NSCLC tumors and studied the relationship between PIK3CA alterations and mutational status of epidermal growth factor receptor (EGFR) signaling pathway genes (EGFR, KRAS, HER2, and BRAF). We also determined PIK3CA expression and activity and correlated the findings with effects on cell growth. We identified mutations in 4.7% of NSCLC cell lines and 1.6% of tumors of all major histologic types. Mutations in cell lines of small cell origin were limited to two ExPuSC cell lines. PIK3CA copy number gains were more frequent in squamous cell carcinoma (33.1%) than in adenocarcinoma (6.2%) or SCLC lines (4.7%). Mutational status of PIK3CA was not mutually exclusive to EGFR or KRAS. PIK3CA alterations were associated with increased phosphatidylinositol 3-kinase activity and phosphorylated Akt expression. RNA interference–mediated knockdown of PIK3CA inhibited colony formation of cell lines with PIK3CA mutations or gains but was not effective in PIK3CA wild-type cells. PIK3CA mutations or gains are present in a subset of lung cancers and are of functional importance. [Cancer Res 2008;68(17):6913–21]
EWS-FLI1 Suppresses NOTCH-Activated p53 in Ewing's Sarcoma
Authors: Ban Jozef , Bennani-Baiti Idriss M. , Kauer Max , Schaefer Karl-Ludwig , Poremba Christopher , Jug Gunhild , Schwentner Raphaela , Smrzka Oskar , Muehlbacher Karin , Aryee Dave N.T. , Kovar Heinrich
Published: August 2008

Although p53 is the most frequently mutated gene in cancer, half of human tumors retain wild-type p53, whereby it is unknown whether normal p53 function is compromised by other cancer-associated alterations. One example is Ewing's sarcoma family tumors (ESFT), where 90% express wild-type p53. ESFT are characterized by EWS-FLI1 oncogene fusions. Studying 6 ESFT cell lines, silencing of EWS-FLI1 in a wild-type p53 context resulted in increased p53 and p21WAF1/CIP1 levels, causing cell cycle arrest. Using a candidate gene approach, HEY1 was linked to p53 induction. HEY1 was rarely expressed in 59 primary tumors, but consistently induced upon EWS-FLI1 knockdown in ESFT cell lines. The NOTCH signaling pathway targets HEY1, and we show NOTCH2 and NOTCH3 to be expressed in ESFT primary tumors and cell lines. Upon EWS-FLI1 silencing, NOTCH3 processing accompanied by nuclear translocation of the activated intracellular domain was observed in all but one p53-mutant cell line. In cell lines with the highest HEY1 induction, NOTCH3 activation was the consequence of JAG1 transcriptional induction. JAG1 modulation by specific siRNA, NOTCH-processing inhibition by either GSI or ectopic NUMB1, and siRNA-mediated HEY1 knockdown all inhibited p53 and p21WAF1/CIP1 induction. Conversely, forced expression of JAG1, activated NOTCH3, or HEY1 induced p53 and p21WAF1/CIP1. These results indicate that suppression of EWS-FLI1 reactivates NOTCH signaling in ESFT cells, resulting in p53-dependent cell cycle arrest. Our data link EWS-FLI1 to the NOTCH and p53 pathways and provide a plausible basis both for NOTCH tumor suppressor effects and oncogenesis of cancers that retain wild-type p53. [Cancer Res 2008;68(17):7100–9]
Chondroitin Sulfate E Fragments Enhance CD44 Cleavage and CD44-Dependent Motility in Tumor Cells
Authors: Sugahara Kazuki N. , Hirata Takako , Tanaka Toshiyuki , Ogino Shinji , Takeda Mitsuhiro , Terasawa Hiroaki , Shimada Ichio , Tamura Jun-ichi , ten Dam Gerdy B. , van Kuppevelt Toin H. , Miyasaka Masayuki
Published: August 2008

During tumor cell invasion, certain extracellular matrix (ECM) components such as hyaluronan (HA) are degraded into small oligosaccharides, which are detected in patients. We previously reported that such HA oligosaccharides induce the proteolytic cleavage of an ECM-binding molecule CD44 from tumor cells and promote tumor cell migration in a CD44-dependent manner. Here, we report that chondroitin sulfate E (CSE), another component of the tumor ECM, strongly enhances CD44 cleavage and tumor cell motility when degraded into oligosaccharides. CSE and its degradation products were detected in pancreatic ductal adenocarcinoma. In CD44-expressing pancreatic tumor cells, degraded forms of CSE but not intact CSE enhanced CD44 cleavage; enzymatic digestion of such low-molecular weight CSE (LMW-CSE) abrogated this enhancement. Among the LMW-CSE preparations examined, 3-kDa CSE most potently induced CD44 cleavage. Nuclear magnetic resonance analysis showed that the 3-kDa-CSE bound to CD44, and that blocking such binding abrogated the CD44 cleavage induction. LMW-CSE also induced prominent filopodia formation and cytoskeletal changes in tumor cells; these effects were also abrogated by blocking the LMW-CSE binding to CD44. Chemically synthesized CSE hexasaccharides also enhanced the CD44 cleavage and tumor cell motility in a CD44-dependent manner. We conclude that the degraded forms of CSE modulate cell adhesion and migration by interacting with tumor-cell CD44, suggesting that the degradation products of tumor-associated ECMs that interact with CD44 play a significant role in CD44-mediated tumor progression. [Cancer Res 2008;68(17):7191–9]
Molecular Basis for the Induction of an Angiogenesis Inhibitor, Thrombospondin-1, by 5-Fluorouracil
Authors: Zhao Hong-Ye , Ooyama Akio , Yamamoto Masatatsu , Ikeda Ryuji , Haraguchi Misako , Tabata Sho , Furukawa Tatsuhiko , Che Xiao-Fang , Zhang Shaoxuan , Oka Toshinori , Fukushima Masakazu , Nakagawa Masayuki , Ono Mayumi , Kuwano Michihiko , Akiyama Shin-ichi
Published: August 2008

5-Fluorouracil (5-FU) is one of the most commonly used anticancer drugs in chemotherapy against various solid tumors. 5-FU dose-dependently increased the expression levels of intrinsic antiangiogenic factor thrombospondin-1 (TSP-1) in human colon carcinoma KM12C cells and human breast cancer MCF7 cells. We investigated the molecular basis for the induction of TSP-1 by 5-FU in KM12C cells. Promoter assays showed that the region with the Egr-1 binding site is critical for the induction of TSP-1 promoter activity by 5-FU. The binding of Egr-1 to the TSP-1 promoter was increased in KM12C cells treated with 5-FU. Immunofluorescence staining revealed that 5-FU significantly increased the level of Egr-1 in the nuclei of KM12C cells. The suppression of Egr-1 expression by small interfering RNA decreased the expression level of TSP-1. Furthermore, 5-FU induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and heat shock protein 27 (HSP27). Blockade of the p38 MAPK pathway by SB203580 remarkably inhibited the phosphorylation of HSP27 induced by 5-FU and decreased the induction of Egr-1 and TSP-1 by 5-FU in KM12C cells. These findings suggest that the p38 MAPK pathway plays a crucial role in the induction of Egr-1 by 5-FU and that induced Egr-1 augments TSP-1 promoter activity, with the subsequent production of TSP-1 mRNA and protein. [Cancer Res 2008;68(17):7035–41]
Tissue Prostate-Specific Antigen Facilitates Refractory Prostate Tumor Progression via Enhancing ARA70-Regulated Androgen Receptor Transactivation
Authors: Niu Yuanjie , Yeh Shuyuan , Miyamoto Hiroshi , Li Gonghui , Altuwaijri Saleh , Yuan Jianqun , Han Ruifa , Ma Tengxiang , Kuo Hann-Chorng , Chang Chawnshang
Published: August 2008

Despite being well recognized as the best biomarker for prostate cancer, pathophysiologic roles of prostate-specific antigen (PSA) remain unclear. We report here that tissue PSA may be involved in the hormone-refractory prostate cancer progression. Histologic analyses show that the increased tissue PSA levels are correlated with lower cell apoptosis index and higher cell proliferation rate in hormone-refractory tumor specimens. By stably transfecting PSA cDNA into various prostate cancer cell lines, we found that PSA could promote the growth of androgen receptor (AR)-positive CWR22rv1 and high-passage LNCaP (hormone-refractory prostate cancer cells) but not that of AR-negative PC-3 and DU145 cells. Surprisingly, the protease activity of PSA is not crucial for PSA to stimulate growth and promote AR transactivation. We further showed that increased PSA could enhance ARA70-induced AR transactivation via modulating the p53 pathway that results in the decreased apoptosis and increased cell proliferation in prostate cancer cells. Knockdown of PSA in LNCaP and CWR22rv1 cells causes cell apoptosis and cell growth arrest at the G1 phase. In vitro colony formation assay and in vivo xenografted tumor results showed the suppression of prostate cancer growth via targeting PSA expression. Collectively, our findings suggest that, in addition to being a biomarker, PSA may also become a new potential therapeutic target for prostate cancer. PSA small interfering RNA or smaller molecules that can degrade PSA protein may be developed as alternative approaches to treat the prostate cancer. [Cancer Res 2008;68(17):7110–9]
Transforming Growth Factor β1 Promotes Chromosomal Instability in Human Papillomavirus 16 E6E7–Infected Cervical Epithelial Cells
Authors: Deng Wen , Tsao Sai Wah , Kwok Yvonne K. , Wong Esther , Huang Xiao Ru , Liu Si , Tsang Chi M. , Ngan Hextan Y.S. , Cheung Annie N.Y. , Lan Hui Yao , Guan Xin-Yuan , Cheung Annie L.M.
Published: August 2008

Uterine cervical cancer, the second most frequently occurring cancer in women worldwide, is tightly associated with the expression of high-risk human papillomavirus [mainly human papillomavirus (HPV)-16 and HPV18] oncogenes E6 and E7 and characteristically exhibits chromosomal instability. However, the mechanisms underlying chromosomal instability in cervical cancer are still not fully understood. In this study, we observed that two of three human cervical epithelial cell lines expressing HPV16 E6E7 became immortalized without extensive chromosomal instability and crisis. The introduction of transforming growth factor (TGF)-β1, a multiple functional cytokine/growth factor, in the culture medium induced crisis, which was associated with massive chromosomal end-to-end fusions and other structural aberrations. The distributions of structural aberrations on individual chromosomes were significantly correlated with the profiles of telomere signal–free ends. The immortalized cells that emerged from the TGF-β1–induced crisis showed multiple clonal structural aberrations that were not observed in cells without TGF-β1 treatment. Overexpression of the catalytic subunit of telomerase (hTERT) abolished the effects of TGF-β1 on chromosomal instability. Interestingly, another HPV16 E6E7–expressing cervical cell line that experienced crisis and telomere dysfunction under ordinary culture condition had a higher level of autocrine TGF-β1 production than the other two crisis-free immortalized cell lines. Blocking the TGF-β1 pathway by an inhibitor of TGF-β1 receptor type I prevented the crisis and telomere-mediated chromosomal instability. In addition, more dramatic telomere shortening was observed in cervical intraepithelial neoplasias having higher expression of TGF-β1 in vivo. These results together suggest an important role of TGF-β1 in the early process of cervical carcinogenesis. [Cancer Res 2008;68(17):7200–9]
Manipulation of [11C]-5-Hydroxytryptophan and 6-[18F]Fluoro-3,4-Dihydroxy-l-Phenylalanine Accumulation in Neuroendocrine Tumor Cells
Authors: Neels Oliver C. , Koopmans Klaas P. , Jager Pieter L. , Vercauteren Laya , van Waarde Aren , Doorduin Janine , Timmer-Bosscha Hetty , Brouwers Adrienne H. , de Vries Elisabeth G.E. , Dierckx Rudi A.J.O. , Kema Ido P. , Elsinga Philip H.
Published: August 2008

[11C]-5-Hydroxytryptophan ([11C]HTP) and 6-[18F]fluoro-3,4-dihydroxy-l-phenylalanine ([18F]FDOPA) are used to image neuroendocrine tumors with positron emission tomography. The precise mechanism by which these tracers accumulate in tumor cells is unknown. We aimed to study tracer uptake via large amino acid transporters, peripheral decarboxylation (inhibited by carbidopa), and intracellular breakdown by monoamine oxidase (MAO). [11C]HTP and [18F]FDOPA tracer accumulation was assessed in a human neuroendocrine tumor cell line, BON. The carbidopa experiments were done in a tumor-bearing mouse model. Intracellular [11C]HTP accumulation was 2-fold higher than that of [18F]FDOPA. Cellular transport of both tracers was inhibited by amino-2-norbornanecarboxylic acid. The MAO inhibitors clorgyline and pargyline increased tracer accumulation in vitro. Carbidopa did not influence tracer accumulation in vitro but improved tumor imaging in vivo. Despite lower accumulation in vitro, visualization of [18F]FDOPA is superior to [11C]HTP in the neuroendocrine pancreatic tumor xenograft model. This could be a consequence of the serotonin saturation of BON cells in the in vivo model. [Cancer Res 2008;68(17):7183–90]
RET/PTC Rearrangements Preferentially Occurred in Papillary Thyroid Cancer among Atomic Bomb Survivors Exposed to High Radiation Dose
Authors: Hamatani Kiyohiro , Eguchi Hidetaka , Ito Reiko , Mukai Mayumi , Takahashi Keiko , Taga Masataka , Imai Kazue , Cologne John , Soda Midori , Arihiro Koji , Fujihara Megumu , Abe Kuniko , Hayashi Tomayoshi , Nakashima Masahiro , Sekine Ichiro , Yasui Wataru , Hayashi Yuzo , Nakachi Kei
Published: August 2008

A major early event in papillary thyroid carcinogenesis is constitutive activation of the mitogen-activated protein kinase signaling pathway caused by alterations of a single gene, typically rearrangements of the RET and NTRK1 genes or point mutations in the BRAF and RAS genes. In childhood papillary thyroid cancer, regardless of history of radiation exposure, RET/PTC rearrangements are a major event. Conversely, in adult-onset papillary thyroid cancer among the general population, the most common molecular event is BRAFV600E point mutation, not RET/PTC rearrangements. To clarify which gene alteration, chromosome aberration, or point mutation preferentially occurs in radiation-associated adult-onset papillary thyroid cancer, we have performed molecular analyses on RET/PTC rearrangements and BRAFV600E mutation in 71 papillary thyroid cancer cases among atomic bomb survivors (including 21 cases not exposed to atomic bomb radiation), in relation to radiation dose as well as time elapsed since atomic bomb radiation exposure. RET/PTC rearrangements showed significantly increased frequency with increased radiation dose (Ptrend = 0.002). In contrast, BRAFV600E mutation was less frequent in cases exposed to higher radiation dose (Ptrend < 0.001). Papillary thyroid cancer subjects harboring RET/PTC rearrangements developed this cancer earlier than did cases with BRAFV600E mutation (P = 0.03). These findings were confirmed by multivariate logistic regression analysis. These results suggest that RET/PTC rearrangements play an important role in radiation-associated thyroid carcinogenesis. [Cancer Res 2008;68(17):7176–82]
Gemcitabine and Cytosine Arabinoside Cytotoxicity: Association with Lymphoblastoid Cell Expression
Authors: Li Liang , Fridley Brooke , Kalari Krishna , Jenkins Gregory , Batzler Anthony , Safgren Stephanie , Hildebrandt Michelle , Ames Matthew , Schaid Daniel , Wang Liewei
Published: August 2008

Two cytidine analogues, gemcitabine (dFdC) and 1-β-d-arabinofuranosylcytosine (AraC), show significant therapeutic effect in a variety of cancers. However, response to these drugs varies widely. Evidence from tumor biopsy samples shows that expression levels for genes involved in the cytidine transport, metabolism, and bioactivation pathway contribute to this variation in response. In the present study, we set out to test the hypothesis that variation in gene expression both within and outside of this “pathway” might influence sensitivity to gemcitabine and AraC. Specifically, Affymetrix U133 Plus 2.0 GeneChip and cytotoxicity assays were performed to obtain basal mRNA expression and IC50 values for both drugs in 197 ethnically defined Human Variation Panel lymphoblastoid cell lines. Genes with a high degree of association with IC50 values were involved mainly in cell death, cancer, cell cycle, and nucleic acid metabolism pathways. We validated selected significant genes by performing real-time quantitative reverse transcription-PCR and selected two representative candidates, NT5C3 (within the pathway) and FKBP5 (outside of the pathway), for functional validation. Those studies showed that down-regulation of NT5C3 and FKBP5 altered tumor cell sensitivity to both drugs. Our results suggest that cell-based model system studies, when combined with complementary functional characterization, may help to identify biomarkers for response to chemotherapy with these cytidine analogues. [Cancer Res 2008;68(17):7050–8]
EBV Is Necessary for Proliferation of Dually Infected Primary Effusion Lymphoma Cells
Authors: Mack Amanda A. , Sugden Bill
Published: August 2008

Epstein Barr virus (EBV) and Kaposi's sarcoma–associated herpesvirus (KSHV) are found together in ∼80% of primary effusion lymphomas (PEL), but their contribution to these cancers is unclear. We found that dominant-negative derivatives of EBNA1 inhibited EBV-positive PEL cells from forming colonies. Those rare PEL cells that proliferated after expression of the dominant-negative derivatives usually expressed these derivatives at low or undetectable levels and continued to maintain their EBV genomes. Those proliferating cells expressing higher levels of the derivatives expressed mutant derivatives that could not bind DNA. These findings indicate that EBV is required to sustain proliferation, as measured by colony formation of dually infected PEL cells. The dominant-negative derivatives of EBNA1 had no effect on the colony-forming ability of five EBV-negative, KSHV-negative hematopoietic cell lines. Surprisingly, they did inhibit the colony-forming ability of EBV-negative, KSHV-positive PEL cells. The small fraction of cells that continued to proliferate expressed only mutants of the EBNA1 derivatives that could no longer bind DNA. These findings indicate that the site-specific DNA-binding activity of EBNA1 or its derivatives when expressed efficiently in EBV-negative, KSHV-positive PEL cells inhibits their colony formation possibly through their binding to the KSHV genome. [Cancer Res 2008;68(17):6963–8]
Inhibition of Activated Fibroblast Growth Factor Receptor 2 in Endometrial Cancer Cells Induces Cell Death Despite PTEN Abrogation
Authors: Byron Sara A. , Gartside Michael G. , Wellens Candice L. , Mallon Mary A. , Keenan Jack B. , Powell Matthew A. , Goodfellow Paul J. , Pollock Pamela M.
Published: August 2008

KRAS activation and PTEN inactivation are frequent events in endometrial tumorigenesis, occurring in 10% to 30% and 26% to 80% of endometrial cancers, respectively. Because we have recently shown activating mutations in fibroblast growth factor receptor 2 (FGFR2) in 16% of endometrioid endometrial cancers, we sought to determine the genetic context in which FGFR2 mutations occur. Analysis of 116 primary endometrioid endometrial cancers revealed that FGFR2 and KRAS mutations were mutually exclusive, whereas FGFR2 mutations were seen concomitantly with PTEN mutations. Here, we show that shRNA knockdown of FGFR2 or treatment with a pan-FGFR inhibitor, PD173074, resulted in cell cycle arrest and induction of cell death in endometrial cancer cells with activating mutations in FGFR2. This cell death in response to FGFR2 inhibition occurred within the context of loss-of-function mutations in PTEN and constitutive AKT phosphorylation, and was associated with a marked reduction in extracellular signal-regulated kinase 1/2 activation. Together, these data suggest that inhibition of FGFR2 may be a viable therapeutic option in endometrial tumors possessing activating mutations in FGFR2, despite the frequent abrogation of PTEN in this cancer type. [Cancer Res 2008;68(17):6902–7]
HEXIM1 Regulates 17β-Estradiol/Estrogen Receptor-α–Mediated Expression of Cyclin D1 in Mammary Cells via Modulation of P-TEFb
Authors: Ogba Ndiya , Chaplin Laura J. , Doughman Yong Qiu , Fujinaga Koh , Montano Monica M.
Published: August 2008

Estrogen receptor α (ERα) plays a key role in mammary gland development and is implicated in breast cancer through the transcriptional regulation of genes linked to proliferation and apoptosis. We previously reported that hexamethylene bisacetamide inducible protein 1 (HEXIM1) inhibits the activity of ligand-bound ERα and bridges a functional interaction between ERα and positive transcription elongation factor b (P-TEFb). To examine the consequences of a functional HEXIM1-ERα-P-TEFb interaction in vivo, we generated MMTV/HEXIM1 mice that exhibit mammary epithelial-specific and doxycycline-inducible expression of HEXIM1. Increased HEXIM1 expression in the mammary gland decreased estrogen-driven ductal morphogenesis and inhibited the expression of cyclin D1 and serine 2 phosphorylated RNA polymerase II (S2P RNAP II). In addition, increased HEXIM1 expression in MCF-7 cells led to a decrease in estrogen-induced cyclin D1 expression, whereas down-regulation of HEXIM1 expression led to an enhancement of estrogen-induced cyclin D1 expression. Studies on the mechanism of HEXIM1 regulation on estrogen action indicated a decrease in estrogen-stimulated recruitment of ERα, P-TEFb, and S2P RNAP II to promoter and coding regions of ERα-responsive genes pS2 and CCND1 with increased HEXIM1 expression in MCF-7 cells. Notably, increased HEXIM1 expression decreased only estrogen-induced P-TEFb activity. Whereas there have been previous reports on HEXIM1 inhibition of P-TEFb activity, our studies add a new dimension by showing that E2/ER is an important regulator of the HEXIM1/P-TEFb functional unit in breast cells. Together, these studies provide novel insight into the role of HEXIM1 and ERα in mammary epithelial cell function. [Cancer Res 2008;68(17):7015–24]
Chemoprevention and Treatment of Experimental Cowden's Disease by mTOR Inhibition with Rapamycin
Authors: Squarize Cristiane H. , Castilho Rogerio M. , Gutkind J. Silvio
Published: August 2008

Cowden's disease is an autosomal dominant disorder characterized by the development of multiple mucocutaneous lesions and benign tumors, and enhanced cancer predisposition. Most Cowden's disease patients harbor inactivating mutations in the PTEN tumor suppressor gene which encodes a lipid phosphatase, PTEN, which restrains the phosphatidylinositol 3-kinase–Akt signaling pathway. We observed that the epithelial-specific deletion of Pten in mice causes multiple hyperproliferative and tumor lesions that strikingly resemble Cowden's disease. This animal model system provided an opportunity to explore novel therapeutic approaches in Cowden's disease. Indeed, we show here that rapamycin administration, which inhibits a key downstream target of Akt, mammalian target of rapamycin (mTOR), promotes the rapid regression of advanced mucocutaneous lesions. Furthermore, when administered before disease manifestation, rapamycin can halt the development of Cowden's disease–like lesions, thereby prolonging animal survival. These findings suggest that mTOR inhibition with rapamycin may represent a suitable therapeutic option for the chemoprevention and treatment of Cowden disease patients and others tumor syndromes that involve defective PTEN function. [Cancer Res 2008;68(17):7066–72]
CREB3L2-PPARγ Fusion Mutation Identifies a Thyroid Signaling Pathway Regulated by Intramembrane Proteolysis
Authors: Lui Weng-Onn , Zeng Lingchun , Rehrmann Victoria , Deshpande Seema , Tretiakova Maria , Kaplan Edwin L. , Leibiger Ingo , Leibiger Barbara , Enberg Ulla , Höög Anders , Larsson Catharina , Kroll Todd G.
Published: August 2008

The discovery of gene fusion mutations, particularly in leukemia, has consistently identified new cancer pathways and led to molecular diagnostic assays and molecular-targeted chemotherapies for cancer patients. Here, we report our discovery of a novel CREB3L2-PPARγ fusion mutation in thyroid carcinoma with t(3;7)(p25;q34), showing that a family of somatic PPARγ fusion mutations exist in thyroid cancer. The CREB3L2-PPARγ fusion encodes a CREB3L2-PPARγ fusion protein that is composed of the transactivation domain of CREB3L2 and all functional domains of PPARγ1. CREB3L2-PPARγ was detected in <3% of thyroid follicular carcinomas. Engineered overexpression of CREB3L2-PPARγ induced proliferation by 40% to 45% in primary human thyroid cells, consistent with a dominant oncogenic mechanism. Wild-type CREB3L2 was expressed in the thyroid as a bZIP transcription factor with a transmembrane domain that has flanking S1P and S2P proteolytic cleavage sites. Native CREB3L2 was cleaved to nuclear CREB3L2 by regulated intramembrane proteolysis in normal thyroid cells that expressed the S1P and S2P proteases. Nuclear CREB3L2 stimulated transcription 8-fold from the EVX1 cyclic AMP (cAMP) response element in the absence of cAMP, whereas CREB3L2-PPARγ inhibited transcription 6-fold from EVX1 in the same experiments. CREB3L2-PPARγ also inhibited 4-fold the expression of thyroglobulin, a native cAMP-responsive gene, in primary thyroid cells treated with thyroid-stimulating hormone. Our findings identify a novel CREB3L2-PPARγ gene fusion mutation in thyroid carcinoma and reveal a thyroid signaling pathway that is regulated by intramembrane proteolysis and disrupted in cancer. [Cancer Res 2008;68(17):7156–64]
BCR/ABL and Other Kinases from Chronic Myeloproliferative Disorders Stimulate Single-Strand Annealing, an Unfaithful DNA Double-Strand Break Repair
Authors: Cramer Kimberly , Nieborowska-Skorska Margaret , Koptyra Mateusz , Slupianek Artur , Penserga Emir Tyrone P. , Eaves Connie J. , Aulitzky Walter , Skorski Tomasz
Published: August 2008

Myeloproliferative disorders (MPD) are stem cell–derived clonal diseases arising as a consequence of acquired aberrations in c-ABL, Janus-activated kinase 2 (JAK2), and platelet-derived growth factor receptor (PDGFR) that generate oncogenic fusion tyrosine kinases (FTK), including BCR/ABL, TEL/ABL, TEL/JAK2, and TEL/PDGFβR. Here, we show that FTKs stimulate the formation of reactive oxygen species and DNA double-strand breaks (DSB) both in hematopoietic cell lines and in CD34+ leukemic stem/progenitor cells from patients with chronic myelogenous leukemia (CML). Single-strand annealing (SSA) represents a relatively rare but very unfaithful DSB repair mechanism causing chromosomal aberrations. Using a specific reporter cassette integrated into genomic DNA, we found that BCR/ABL and other FTKs stimulated SSA activity. Imatinib-mediated inhibition of BCR/ABL abrogated this effect, implicating a kinase-dependent mechanism. Y253F, E255K, T315I, and H396P mutants of BCR/ABL that confer imatinib resistance also stimulated SSA. Increased expression of either nonmutated or mutated BCR/ABL kinase, as is typical of blast phase cells and very primitive chronic phase CML cells, was associated with higher SSA activity. BCR/ABL-mediated stimulation of SSA was accompanied by enhanced nuclear colocalization of RAD52 and ERCC1, which play a key role in the repair. Taken together, these findings suggest a role of FTKs in causing disease progression in MPDs by inducing chromosomal instability through the production of DSBs and stimulation of SSA repair. [Cancer Res 2008;68(17):6884–8]
Illegitimate WNT Pathway Activation by β-Catenin Mutation or Autocrine Stimulation in T-Cell Malignancies
Authors: Groen Richard W.J. , Oud Monique E.C.M. , Schilder-Tol Esther J.M. , Overdijk Marije B. , ten Berge Derk , Nusse Roel , Spaargaren Marcel , Pals Steven T.
Published: August 2008

Recent studies in mice have shown a role for the canonical WNT pathway in lymphocyte development. Because cancers often arise as a result of aberrant activation of signaling cascades that normally promote the self-renewal and expansion of their progenitor cells, we hypothesized that activation of the WNT pathway might contribute to the pathogenesis of lymphoproliferative disease. Therefore, we screened a large panel (n = 162) of non–Hodgkin lymphomas (NHL), including all major WHO categories, for nuclear expression of β-catenin, a hallmark of “active” WNT signaling. In 16 lymphomas, mostly of T-lineage origin, nuclear localization of β-catenin was detected. Interestingly, some of these tumors contained established gain-of-function mutations in the gene encoding β-catenin (CTNNB1); however, in the majority, mutations in either CTNNB1 or APC were not detected. Functional analysis of WNT signaling in precursor T-lymphoblastic lymphomas/leukemias, the NHL subset in which β-catenin accumulation was most prevalent (33% positive), revealed a constitutively activated, but still responsive, WNT pathway, which controlled T-cell factor–mediated gene transcription and cell growth. Our data indicate that activation of the WNT pathway, either by CTNNB1 mutation or autocrine stimulation, plays a role in the pathogenesis of a subset of NHLs, in particular, those of T-cell origin. [Cancer Res 2008;68(17):6969–77]
Is Continuous Treatment with Transforming Growth Factor-Beta Necessary to Induce Chondrogenic Differentiation in Mesenchymal Stem Cells?
Authors: Kim Hye-Joung , Kim Young-Ju , Im Gun-Il
Published: August 2008

This study was conducted to determine whether short-term administration of transforming growth factor (TGF)-β would be as effective for inducing chondrogenesis in human mesenchymal stem cells (hMSCs) as continuous treatment. Four groups of hMSCs were cultured in a monolayer for 3 days followed by a pellet culture for 3 weeks under various conditions: group A, the control group, no growth factors treated; group B, 5 ng/ml of TGF-β2 was treated for 3 days in monolayer culture; group C, 5 ng/ml of TGF-β2 was treated for 3 days in a monolayer culture and the initial 3 days of pellet culture; group D, 5 ng/ml of TGF-β2 was treated for 3 days in a monolayer culture and the initial 10 days of pellet culture; group E, 5 ng/ml of TGF-β2 was continuously treated throughout the culture period. Glycosaminoglycan contents significantly increased in group E only. Real-time PCR indicated that expression of Sox-9, type II collagen, type II procollagen B and type X collagen increased with longer duration of TGF-β2 treatment. The histological findings showed that longer duration of TGF-β2 treatment led to significantly better quality of chondrogenesis. This study demonstrated that longer duration of TGF-β treatment is necessary for effective chondrogenesis in hMSCs from bone marrow.
Anticoagulant Effect of Dietary Fish Oil in Hyperlipidemia
Authors: Vanschoonbeek Kristof , Wouters Kristiaan , van der Meijden Paola E.J. , van Gorp Patrick J. , Feijge Marion A.H. , Herfs Marjolein , Schurgers Leon J. , Hofker Marten H. , de Maat Moniek P.M. , Heemskerk Johan W.M.
Published: August 2008

Objective—

In hyperlipidemia, dietary fish oil containing n-3 polyunsaturated fatty acids (PUFA) provokes plasma triacylglycerol lowering and hypocoagulant activity. Using APOE2 knock-in mice, the relation of these fish-oil effects with altered gene expression was investigated.

Methods and Results—

Male APOE2 knock-in mice, fed regular low-fat diet, had elevated plasma levels of triacylglycerol and coagulation factors. Plasma lipids and (anti)coagulant factors reduced on feeding the mice with fish oil (n-3 PUFA) or, to a lesser degree, with sunflowerseed oil (n-6 PUFA). The fish-oil diet provoked a 40% reduction in thrombin generation. Microarray (Affymetrix) and single-gene expression analysis of mouse livers showed that fish oil induced: (1) upregulation of genes contributing to lipid degradation and oxidation; (2) downregulation of genes of γ-glutamyl carboxylase and of transcription factors implicated in lipid synthesis; (3) unchanged expression of coagulation factor genes. After fish-oil diet, vitamin K–dependent coagulation factors accumulated in periportal areas of the liver; prothrombin was partly retained in uncarboxylated form. Only part of the changes in gene expression were different from the effects of sunflowerseed oil diet.

Conclusions—

The hypocoagulant effect of n-3 PUFA is not caused by reduced hepatic synthesis of coagulation factors, but rather results from retention of uncarboxylated coagulation factors. In contrast, the lipid-lowering effect of n-3 PUFA links to altered expression of genes that regulate transcription and fatty acid metabolism.
Potentially Preventable Strokes in High-Risk Patients With Atrial Fibrillation Who Are Not Adequately Anticoagulated
Authors: Gladstone David J. , Bui Esther , Fang Jiming , Laupacis Andreas , Lindsay M. Patrice , Tu Jack V. , Silver Frank L. , Kapral Moira K.
Published: August 2008

Background and Purpose—

Warfarin is the most effective stroke prevention medication for high-risk individuals with atrial fibrillation, yet it is often underused. This study examined the magnitude of this problem in a large contemporary, prospective stroke registry.

Methods—

We analyzed data from the Registry of the Canadian Stroke Network, a prospective database of consecutive patients with stroke admitted to 12 designated stroke centers in Ontario (2003 to 2007). We included patients admitted with an acute ischemic stroke who (1) had a known history of atrial fibrillation; (2) were classified as high risk for systemic emboli according to published guidelines; and (3) had no known contraindications to anticoagulation. Primary end points were the use of prestroke antithrombotic medications and admission international normalized ratio.

Results—

Among patients admitted with a first ischemic stroke who had known atrial fibrillation (n=597), strokes were disabling in 60% and fatal in 20%. Preadmission medications were warfarin (40%), antiplatelet therapy (30%), and no antithrombotics (29%). Of those taking warfarin, three fourths had a subtherapeutic international normalized ratio (<2.0) at the time of stroke admission. Overall, only 10% of patients with acute stroke with known atrial fibrillation were therapeutically anticoagulated (international normalized ratio ≥2.0) at admission. In stroke patients with a history of atrial fibrillation and a previous transient ischemic attack or ischemic stroke (n=323), only 18% were taking warfarin with therapeutic international normalized ratio at the time of admission for stroke, 39% were taking warfarin with subtherapeutic international normalized ratio, and 15% were on no antithrombotic therapy.

Conclusions—

In high-risk patients with atrial fibrillation admitted with a stroke, and who were candidates for anticoagulation, most were either not taking warfarin or were subtherapeutic at the time of ischemic stroke. Many were on no antithrombotic therapy. These findings should encourage greater efforts to prescribe and monitor appropriate antithrombotic therapy to prevent stroke in individuals with atrial fibrillation.
Reperfusion-Associated Hemorrhagic Transformation in SHR Rats
Authors: Henning Erica C. , Latour Lawrence L. , Hallenbeck John M. , Warach Steven
Published: August 2008

Background and Purpose—

Symptomatic hemorrhagic transformation (HT) is the most important complicating factor after treatment with intravenous tissue plasminogen activator. In this study, we used multimodal magnetic resonance imaging to investigate the incidence and severity of reperfusion-based HT in spontaneously hypertensive rats after ischemia/reperfusion.

Methods—

Twenty male spontaneously hypertensive rats were subjected to 30 minutes of middle cerebral artery occlusion via the suture model. Diffusion-weighted, T
2
-weighted, and gradient-echo imaging were performed on days 1, 2, 3, 4, and 7 for longitudinal evaluation of lesion evolution, vasogenic edema, and HT, respectively. Findings on gradient-echo images were classified according to the severity of hemorrhage: no HT; punctate or small petechial hemorrhage (HI-1); confluent petechial hemorrhage (HI-2); hematoma with absent/mild space-occupying effect (PH-1, ≤30% lesion volume); and hematoma with significant space-occupying effect and potential perihematomal edema (PH-2, >30% lesion volume). Histopathologic evaluation of HT was performed after final imaging for comparison with magnetic resonance imaging results.

Results—

Final hemorrhage scores based on severity were as follows: HI-1 23.1%, HI-2 30.8%, PH-1 30.8%, and PH-2 15.4%. Similar to clinical observations, only PH-2 was associated with neurologic deterioration and associated weight loss.

Conclusions—

This model has a high incidence of parenchymal hematomas (46.2%) and therefore is appropriate for the evaluation of novel therapeutics targeting blood-brain barrier integrity and the reduction of symptomatic HT events (PH-2), as well as those potentially “at risk” for neurologic deterioration (PH-1).
Treadmill Exercise Activates Subcortical Neural Networks and Improves Walking After Stroke
Authors: Luft Andreas R. , Macko Richard F. , Forrester Larry W. , Villagra Federico , Ivey Fred , Sorkin John D. , Whitall Jill , McCombe-Waller Sandy , Katzel Leslie , Goldberg Andrew P. , Hanley Daniel F.
Published: August 2008

Background and Purpose—

Stroke often impairs gait thereby reducing mobility and fitness and promoting chronic disability. Gait is a complex sensorimotor function controlled by integrated cortical, subcortical, and spinal networks. The mechanisms of gait recovery after stroke are not well understood. This study examines the hypothesis that progressive task-repetitive treadmill exercise (T-EX) improves fitness and gait function in subjects with chronic hemiparetic stroke by inducing adaptations in the brain (plasticity).

Methods—

A randomized controlled trial determined the effects of 6-month T-EX (n=37) versus comparable duration stretching (CON, n=34) on walking, aerobic fitness and in a subset (n=15/17) on brain activation measured by functional MRI.

Results—

T-EX significantly improved treadmill-walking velocity by 51% and cardiovascular fitness by 18% (11% and −3% for CON, respectively;
P
<0.05). T-EX but not CON affected brain activation during paretic, but not during nonparetic limb movement, showing 72% increased activation in posterior cerebellar lobe and 18% in midbrain (
P
<0.005). Exercise-mediated improvements in walking velocity correlated with increased activation in cerebellum and midbrain.

Conclusions—

T-EX improves walking, fitness and recruits cerebellum-midbrain circuits, likely reflecting neural network plasticity. This neural recruitment is associated with better walking. These findings demonstrate the effectiveness of T-EX rehabilitation in promoting gait recovery of stroke survivors with long-term mobility impairment and provide evidence of neuroplastic mechanisms that could lead to further refinements in these paradigms to improve functional outcomes.
Complex Sequelae of Psychological Trauma Among Kosovar Civilian War Victims
Authors: Morina Nexhmedin , Ford Julian D.
Published: August 2008

Aims: The impact of war trauma on civilians may include, but also extend beyond, post-traumatic stress disorder (PTSD) to include complex sequelae such as those described by the syndrome of Disorders of Extreme Stress Not Otherwise Specified (DESNOS).

Methods: In the present study, 102 civilian war victims were interviewed in Kosovo, assessing traumatic life events, PTSD, DESNOS, and depression.

Results: Full DESNOS rarely occurred (2% prevalence), however, clinically significant DESNOS symptoms of somatization, altered relationships, and altered systems of meaning were reported by between 24—42% of respondents. Although DESNOS symptoms were correlated with PTSD symptoms, DESNOS symptoms were associated with poorer overall psychological functioning, self-evaluations, satisfaction with life, and social support independent of the effects of PTSD.

Conclusion: The findings suggest that DESNOS warrants attention in addition to PTSD in the assessment and treatment of civilians who have been exposed to war and genocide.
The Influence of Socio-Economic Conditions On the Prevalence of Depressive Symptoms and Its Covariates in an Elderly Population With Slight Income Differences: the Bambuí Health and Aging Study (Bhas)
Authors: Carvalhais S.M.M. , Lima-Costa M.F. , Peixoto S.V. , Firmo J.O.A. , Castro-Costa E. , Uchoa E.
Published: August 2008

Background: The influence of socio-economic conditions on covariates of depression has received little attention.

Aims: Examine whether prevalence and covariates of depressive symptoms are affected by socio-economic circumstances.

Methods: Participants were 1,499 (86%) residents in Bambuí city, Brazil, aged ->- 60 years. Depressive symptoms were assessed by the GHQ-12 questionnaire and exploratory variables included demographic characteristics, life events, social support, health conditions and health service use. The analysis was stratified by family income (< US$240.00 [lowest tertile] vs. ->- US$240.00).

Results: The prevalence of depressive symptoms was higher in those with lower income (43.9%) in comparison with the better off (27.7%). Dissatisfaction with relationships, worse self-rated health and insomnia were independently associated with depressive symptoms in both income groups (OR from 2.00 to 4.74; p < 0.05). Depressive symptoms were associated with number of chronic diseases, functional disability and hospitalizations among the poorer (OR from 1.73 to 2.37; p < 0.05), while old age (OR 2.08) and female gender (OR 2.03) were associated with depressive symptoms among the better off.

Conclusion: This study provides evidence that the prevalence of depressive symptoms and their covariates are influenced by socio-economic conditions in a population with slight income differences.