bluuebunny/crossref_metadata_2025 huggingface dataset:
Targeting of AKT1 enhances radiation toxicity of human tumor cells by inhibiting DNA-PKcs-dependent DNA double-strand break repair
Authors: Toulany Mahmoud , Kehlbach Rainer , Florczak Urszula , Sak Ali , Wang Shaomeng , Chen Jianyong , Lobrich Markus , Rodemann H. Peter
Published: July 2008

We have already reported that epidermal growth factor receptor/phosphatidylinositol 3-kinase/AKT signaling is an important pathway in regulating radiation sensitivity and DNA double-strand break (DNA-dsb) repair of human tumor cells. In the present study, we investigated the effect of AKT1 on DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activity and DNA-dsb repair in irradiated non-small cell lung cancer cell lines A549 and H460. Treatment of cells with the specific AKT pathway inhibitor API-59CJ-OH (API; 1-5 μmol/L) reduced clonogenic survival between 40% and 85% and enhanced radiation sensitivity of both cell lines significantly. As indicated by fluorescence-activated cell sorting analysis (sub-G1 cells) and poly(ADP-ribose) polymerase cleavage, API treatment or transfection with AKT1-small interfering RNA (siRNA) induced apoptosis of H460 but not of A549 cells. However, in either apoptosis-resistant A549 or apoptosis-sensitive H460 cells, API and/or AKT1-siRNA did not enhance poly(ADP-ribose) polymerase cleavage and apoptosis following irradiation. Pretreatment of cells with API or transfection with AKT1-siRNA strongly inhibited radiation-induced phosphorylation of DNA-PKcs at T2609 and S2056 as well as repair of DNA-dsb as measured by the γ-H2AX foci assay. Coimmunoprecipitation experiments showed a complex formation of activated AKT and DNA-PKcs, supporting the assumption that AKT plays an important regulatory role in the activation of DNA-PKcs in irradiated cells. Thus, targeting of AKT enhances radiation sensitivity of lung cancer cell lines A549 and H460 most likely through specific inhibition of DNA-PKcs-dependent DNA-dsb repair but not through enhancement of radiation-induced apoptosis. [Mol Cancer Ther 2008;7(7):1772–81]
Key role for Bak activation and Bak-Bax interaction in the apoptotic response to vinblastine
Authors: Upreti Meenakshi , Chu Rong , Galitovskaya Elena , Smart Sherri K. , Chambers Timothy C.
Published: July 2008

Microtubule inhibitors such as vinblastine cause mitotic arrest and subsequent apoptosis through the intrinsic mitochondrial pathway. However, although Bcl-2 family proteins have been implicated as distal mediators, their precise role is largely unknown. In this study, we investigated the role of Bak in vinblastine-induced apoptosis. Bak was mainly monomeric in untreated KB-3 cells, and multimers corresponding to dimer, trimer, and higher oligomers were observed after vinblastine treatment. The oligomeric Bak species were strongly diminished in cells stably overexpressing Bcl-xL. Immunoprecipitation with a conformation-dependent Bak antibody revealed that vinblastine induced Bak activation. Reciprocal immunoprecipitations indicated that vinblastine induced the interaction of active Bak with active Bax. Furthermore, Bcl-xL overexpression prevented Bak and Bax interaction and strongly inhibited apoptosis, whereas Bcl-2 overexpression did not prevent Bak-Bax interaction and only weakly inhibited apoptosis. The relative contributions of Bak and Bax were investigated using fibroblasts deficient in one or both of these proteins; double knockouts were highly resistant compared with single knockouts, with vinblastine sensitivities in the order of Bak+/Bax+ > Bak+/Bax- > Bak-/Bax+ > Bak-/Bax-. These results highlight Bak as a key mediator of vinblastine-induced apoptosis and show for the first time activation and oligomerization of Bak by an antimitotic agent. In addition, our results suggest that the interaction of the activated forms of Bak and Bax represents a key distal step in the apoptotic response to this important chemotherapeutic drug. [Mol Cancer Ther 2008;7(7):2224–32]
Antimigratory effect of TK1-2 is mediated in part by interfering with integrin α2β1
Authors: Kim Hyun-Kyung , Oh Dae-Shik , Lee Sang-Bae , Ha Jung-Min , Joe Young Ae
Published: July 2008

The recombinant two kringle domain of human tissue-type plasminogen activator (TK1-2) has been shown to inhibit endothelial cell proliferation, angiogenesis, and tumor cell growth despite of sharing a low amino acid sequence homology with angiostatin. Here, we explored a possible inhibitory mechanism of action of TK1-2 by focusing on antimigratory effect. TK1-2 effectively inhibited endothelial cell migration induced by basic fibroblast growth factor or vascular endothelial growth factor in a dose-dependent manner and tube formation on Matrigel. It blocked basic fibroblast growth factor–induced or vascular endothelial growth factor–induced phosphorylation of extracellular signal-regulated kinase 1/2 and formation of actin stress fibers and focal adhesions. Interestingly, TK1-2 alone induced the weak phosphorylation of focal adhesion kinase, whereas it inhibited focal adhesion kinase phosphorylation induced by growth factors. When immobilized, TK1-2 promoted adhesion and spreading of endothelial cells compared with bovine serum albumin. However, treatment with anti-α2β1 blocking antibody markedly diminished endothelial cell adhesion to immobilized TK1-2 compared with anti-αvβ3 or anti-α5β1 antibody. Pretreatment of soluble TK1-2 also altered the binding level of anti-α2β1 antibody to endothelial cells in fluorescence-activated cell sorting analysis. Indeed, a blocking antibody against integrin α2β1 or knocking down of integrin α2 expression prevented the inhibitory effect of TK1-2 in cell migration. Therefore, these results suggest that TK1-2 inhibits endothelial cell migration through inhibition of signaling and cytoskeleton rearrangement in part by interfering with integrin α2β1. [Mol Cancer Ther 2008;7(7):2133–41]
Antiproliferative effect of sulindac in colonic neoplasia prevention: role of COOH-terminal Src kinase
Authors: Kunte Dhananjay P. , Wali Ramesh K. , Koetsier Jennifer L. , Roy Hemant K.
Published: July 2008

Although the nonsteroidal anti-inflammatory drugs (NSAID) protection against colorectal cancer is well established, the molecular mechanisms remain unclear. We show herein that induction of the tumor suppressor gene COOH-terminal Src kinase (Csk) by NSAID is important for their antiproliferative and hence chemopreventive effects. In the azoxymethane-treated rat model of experimental colon carcinogenesis, sulindac treatment markedly induced Csk with a corresponding increase in inhibitory phosphorylation of Src (Tyr527). Sulindac-mediated Csk induction was replicated in the human colorectal cancer cell line HT-29, with a corresponding suppression of both Src kinase activity (63% of vehicle; P < 0.05) and E-cadherin tyrosine phosphorylation (an in vivo Src target). To determine the importance of Csk in NSAID antiproliferative activity, we stably transfected a Csk-specific short hairpin RNA (shRNA) vector into HT-29 cells, thereby blunting the sulindac-mediated Csk induction. These transfectants were significantly less responsive to the antiproliferative effect of sulindac sulfide (suppression of proliferating cell nuclear antigen was 21 ± 2.3% in transfectants versus 45 ± 4.23% in wild-type cells), with a corresponding mitigation of the sulindac-mediated G1-S-phase arrest (S-phase cells 48 ± 3.6% versus 14 ± 2.8% of vehicle respectively). Importantly, the Csk shRNA cells had a marked decrease in the cyclin-dependent kinase inhibitor p21cip/waf1, a critical regulator of G1-S-phase progression (49% of wild-type cells). Moreover, although sulindac-mediated induction of p21cip/waf1 was 113% in wild-type HT-29, this induction was alleviated in the Csk shRNA transfectants (65% induction; P < 0.01). Thus, this is the first demonstration that the antiproliferative activity of NSAID is modulated, at least partly, through the Csk/Src axis. [Mol Cancer Ther 2008;7(7):1797–806]
Targeting Lyn inhibits tumor growth and metastasis in Ewing's sarcoma
Authors: Guan Hui , Zhou Zhichao , Gallick Gary E. , Jia Shu-Fang , Morales Jaime , Sood Anil K. , Corey Seth J. , Kleinerman Eugenie S.
Published: July 2008

Src family tyrosine kinases (SFK) play an important role in growth and metastasis of many types of human malignancies. However, their significance in Ewing's sarcoma remains to be elucidated. The purpose of this study was to evaluate the role of Lyn, one member of the SFK, in Ewing's sarcoma growth and metastasis and to determine whether a SFK inhibitor can induce Ewing's tumor regression. Lyn was expressed and activated in TC71, A4573, and SK-ES human Ewing's sarcoma cells. Lyn expression was seen in 13 of 15 patient tumor samples, 6 of which showed Lyn activation. Specific inhibition of Lyn using small interfering RNA significantly decreased primary tumor growth and lytic activity, and also reduced lung metastases in vivo. Down-regulation of Lyn resulted in decreased invasive capacity of tumor cells in vitro. AP23994, a small-molecule SFK inhibitor, decreased Lyn kinase activity and suppressed TC71 cell growth in vitro in a dose-dependent manner. Furthermore, treatment of mice bearing s.c. TC71 tumors with AP23994 or with polyethylenimine/Lyn-small interfering RNA gene therapy resulted in reduced Lyn kinase activity and significant tumor growth suppression. EWS/FLI-1, which is translocation fusion protein associated with Ewing's sarcoma, regulated Lyn gene expression and kinase activity. These data suggest that targeting Lyn may be a new therapeutic approach in treatment of Ewing's sarcoma. [Mol Cancer Ther 2008;7(7):1807–16]
S1P differentially regulates migration of human ovarian cancer and human ovarian surface epithelial cells
Authors: Wang Dongmei , Zhao Zhenwen , Caperell-Grant Andrea , Yang Gong , Mok Samuel C. , Liu Jinsong , Bigsby Robert M. , Xu Yan
Published: July 2008

Epithelial ovarian cancer (EOC) arises from the epithelial layer covering the surface of ovaries and i.p. metastasis is commonly observed at diagnosis. Sphingosine-1-phosphate (S1P), a bioactive lipid signaling molecule, is potentially involved in EOC tumorigenesis. We have found that S1P is elevated in human EOC ascites. We show that physiologically relevant concentrations of S1P stimulate migration and invasion of EOC cells but inhibit migration of human ovarian surface epithelial (HOSE) cells. In addition, S1P inhibits lysophosphatidic acid (LPA)–induced cell migration in HOSE but not in EOC cells. We have provided the first line of evidence that the expression levels of S1P receptor subtypes are not the only determinants for how cells respond to S1P. Although S1P1 is expressed and functional in HOSE cells, the inhibitory effect mediated by S1P2 is dominant in those cells. The cellular preexisting stress fibers are also important determinants for the migratory response to S1P. Differential S1P-induced morphology changes are noted in EOC and HOSE cells. Preexisting stress fibers in HOSE cells are further enhanced by S1P treatment, resulting in the negative migratory response to S1P. By contrast, EOC cells lost stress fibers and S1P treatment induces filopodium-like structures at cell edges, which correlates with increased cell motility. In addition, inhibition of the protein kinase C pathway is likely to be involved in the inhibitory effect of S1P on LPA-induced cell migration in HOSE cells. These findings are important for the development of new therapeutics targeting S1P and LPA in EOC. [Mol Cancer Ther 2008;7(7):1993–2002]
Inhibition of centromere dynamics by eribulin (E7389) during mitotic metaphase
Authors: Okouneva Tatiana , Azarenko Olga , Wilson Leslie , Littlefield Bruce A. , Jordan Mary Ann
Published: July 2008

Eribulin (E7389), a synthetic analogue of halichondrin B in phase III clinical trials for breast cancer, binds to tubulin and microtubules. At low concentrations, it suppresses the growth phase of microtubule dynamic instability in interphase cells, arrests mitosis, and induces apoptosis, suggesting that suppression of spindle microtubule dynamics induces mitotic arrest. To further test this hypothesis, we measured the effects of eribulin on dynamics of centromeres and their attached kinetochore microtubules by time-lapse confocal microscopy in living mitotic U-2 OS human osteosarcoma cells. Green fluorescent protein–labeled centromere-binding protein B marked centromeres and kinetochore-microtubule plus-ends. In control cells, sister chromatid centromere pairs alternated under tension between increasing and decreasing separation (stretching and relaxing). Eribulin suppressed centromere dynamics at concentrations that arrest mitosis. At 60 nmol/L eribulin (2 × mitotic IC50), the relaxation rate was suppressed 21%, the time spent paused increased 67%, and dynamicity decreased 35% (but without reduction in mean centromere separation), indicating that eribulin decreased normal microtubule-dependent spindle tension at the kinetochores, preventing the signal for mitotic checkpoint passage. We also examined a more potent, but in tumors less efficacious antiproliferative halichondrin derivative, ER-076349. At 2 × IC50 (4 nmol/L), mitotic arrest also occurred in concert with suppressed centromere dynamics. Although media IC50 values differed 15-fold between the two compounds, the intracellular concentrations were similar, indicating more extensive relative uptake of ER-076349 into cells compared with eribulin. The strong correlation between suppression of kinetochore-microtubule dynamics and mitotic arrest indicates that the primary mechanism by which eribulin blocks mitosis is suppression of spindle microtubule dynamics. [Mol Cancer Ther 2008;7(7):2003–11]
Small-molecule inhibitor of the AP endonuclease 1/REF-1 E3330 inhibits pancreatic cancer cell growth and migration
Authors: Zou Gang-Ming , Maitra Anirban
Published: July 2008

AP endonuclease 1 (APE1; also known as REF-1) contains a DNA repair domain and a redox regulation domain. APE1 is overexpressed in several human cancers, and disruption of APE1 function has detrimental effects on cancer cell viability. However, the selective contribution of the redox and the DNA repair domains to maintenance of cellular homeostasis in cancer has not been elucidated. In the present study, we used E3330, a small-molecule inhibitor of APE1 redox domain function, to interrogate the functional relevance of sustained redox function in pancreatic cancer. We show that E3330 significantly reduces the growth of human pancreatic cancer cells in vitro. This phenomenon was further confirmed by a small interfering RNA experiment to knockdown APE1 expression in pancreatic cancer cells. Further, the growth-inhibitory effects of E3330 are accentuated by hypoxia, and this is accompanied by striking inhibition in the DNA-binding ability of hypoxia-inducible factor-1α, a hypoxia-induced transcription factor. E3330 exposure promotes endogenous reactive oxygen species formation in pancreatic cancer cells, and the resulting oxidative stress is associated with higher levels of oxidized, and hence inactive, SHP-2, an essential protein tyrosine phosphatase that promotes cancer cell proliferation in its active state. Finally, E3330 treatment inhibits pancreatic cancer cell migration as assessed by in vitro chemokine assays. E3330 shows anticancer properties at multiple functional levels in pancreatic cancer, such as inhibition of cancer cell growth and migration. Inhibition of the APE1 redox function through pharmacologic means has the potential to become a promising therapeutic strategy in this disease. [Mol Cancer Ther 2008;7(7):2012–21]
Thiostrepton selectively targets breast cancer cells through inhibition of forkhead box M1 expression
Authors: Kwok Jimmy M-M. , Myatt Stephen S. , Marson Charles M. , Coombes R. Charles , Constantinidou Demetra , Lam Eric W-F.
Published: July 2008

Elevated expression or activity of the transcription factor forkhead box M1 (FOXM1) is associated with the development and progression of many malignancies, including breast cancer. In this study, we show that the thiazole antibiotic thiostrepton selectively induces cell cycle arrest and cell death in breast cancer cells through down-regulating FOXM1 expression. Crucially, our data show that thiostrepton treatment reduced FOXM1 expression in a time- and dose-dependent manner, independent of de novo protein synthesis and predominantly at transcriptional and gene promoter levels. Our results indicate that thiostrepton can induce cell death through caspase-dependent intrinsic and extrinsic apoptotic pathways as well as through caspase-independent death mechanisms, as observed in MCF-7 cells, which are deficient of caspase-3 and caspase-7. Cell cycle analysis showed that thiostrepton induced cell cycle arrest at G1 and S phases and cell death, concomitant with FOXM1 repression in breast cancer cells. Furthermore, thiostrepton also shows efficacy in repressing breast cancer cell migration, metastasis, and transformation, which are all downstream functional attributes of FOXM1. We also show that overexpression of a constitutively active FOXM1 mutant, ΔN-FOXM1, can abrogate the antiproliferative effects of thiostrepton. Interestingly, thiostrepton has no affect on FOXM1 expression and proliferation of the untransformed MCF-10A breast epithelial cells. Collectively, our data show that FOXM1 is one of the primary cellular targets of thiostrepton in breast cancer cells and that thiostrepton may represent a novel lead compound for targeted therapy of breast cancer with minimal toxicity against noncancer cells. [Mol Cancer Ther 2008;7(7):2022–32]
Laser postionization secondary neutral mass spectrometry in tissue: a powerful tool for elemental and molecular imaging in the development of targeted drugs
Authors: Wittig Andrea , Arlinghaus Heinrich F. , Kriegeskotte Christian , Moss Raymond L. , Appelman Klaas , Schmid Kurt W. , Sauerwein Wolfgang A.G.
Published: July 2008

The exact intracellular localization and distribution of molecules and elements becomes increasingly important for the development of targeted therapies and contrast agents. We show that laser postionization secondary neutral mass spectrometry (laser-SNMS) is well suited to localize particular elements and small molecules with subcellular spatial resolution applying the technique exemplary to Boron Neutron Capture Therapy (BNCT). We showed in a murine sarcoma that the drugs used for clinical BNCT, namely l-para-boronophenylalanine (700 mg/kg body weight i.p.) and sodium mercaptoundecahydro-closo-dodecaborate (200 mg/kg body weight i.p.), transport the therapeutic agent 10B into the cytoplasm and into the nucleus itself, the most sensitive area of the cell. Sodium mercaptoundecahydro-closo-dodecaborate distributes 10B homogeneously and l-para-boronophenylalanine heterogeneously. When combining laser-SNMS with prompt γ-ray analysis as a screening technique, strategies for BNCT can be elaborated to develop new drugs or to improve the use of existing drugs on scientifically based evidence. The study shows the power of laser-SNMS in the early stages of drug development, also outside BNCT. [Mol Cancer Ther 2008;7(7):1763–71]
Silibinin inhibits cytokine-induced signaling cascades and down-regulates inducible nitric oxide synthase in human lung carcinoma A549 cells
Authors: Chittezhath Manesh , Deep Gagan , Singh Rana P. , Agarwal Chapla , Agarwal Rajesh
Published: July 2008

Recently, we reported that silibinin inhibits primary lung tumor growth and progression in mice and down-regulates inducible nitric oxide synthase (iNOS) expression in tumors; however, the mechanisms of silibinin action are largely not understood. Also, the activation of signaling pathways inducing various transcription factors are associated with lung carcinogenesis and their inhibition could be an effective strategy to prevent and/or treat lung cancer. Herein, we used human lung epithelial carcinoma A549 cells to explore the potential mechanisms and observed strong iNOS expression by cytokine mixture (containing 100 units/mL IFN-γ + 0.5 ng/mL interleukin-1β + 10 ng/mL tumor necrosis factor-α). We also examined the cytokine mixture–activated signaling cascades, which could potentially up-regulate iNOS expression, and then examined the effect of silibinin (50-200 μmol/L) on these signaling cascades. Silibinin treatment inhibited, albeit to different extent, the cytokine mixture–induced activation of signal transducer and activator of transcription 1 (Tyr701), signal transducer and activator of transcription 3 (Tyr705), activator protein-1 family of transcription factors, and nuclear factor-κB. The results for activator protein-1 were correlated with the decreased nuclear levels of phosphorylated c-Jun, c-Jun, JunB, JunD, phosphorylated c-Fos, and c-Fos. Further, silibinin also strongly decreased cytokine mixture–induced phosphorylation of extracellular signal-regulated kinase 1/2 but only marginally affected JNK1/2 phosphorylation. Silibinin treatment also decreased constitutive p38 phosphorylation in the presence or absence of cytokine mixture. Downstream of these pathways, silibinin strongly decreased cytokine mixture–induced expression of hypoxia-inducible factor-1α without any considerable effect on Akt activation. Cytokine mixture–induced iNOS expression was completely inhibited by silibinin. Overall, these results suggest that silibinin could target multiple cytokine-induced signaling pathways to down-regulate iNOS expression in lung cancer cells and that could contribute to its overall cancer preventive efficacy against lung tumorigenesis. [Mol Cancer Ther 2008;7(7):1817–26]
Active roles for inhibitory κB kinases α and β in nuclear factor-κB–mediated chemoresistance to doxorubicin
Authors: Bednarski Brian K. , Ding Xiaoyu , Coombe Kavita , Baldwin Albert S. , Kim Hong J.
Published: July 2008

Chemotherapy agents have been shown to induce the transcription factor nuclear factor-κB (NF-κB) and subsequent chemoresistance in fibrosarcomas and other cancers. The mechanism of NF-κB-mediated chemoresistance remains unclear, with a previous report suggesting that doxorubicin induces this response independent of the inhibitory κB kinases (IKK). Other studies have indicated that IKKβ, but not IKKα, is required. Mouse embryo fibroblasts devoid of IKKα, IKKβ, or both subunits (double knockout) were treated with doxorubicin. The absence of either IKKα or IKKβ or both kinases resulted in impaired induction of NF-κB DNA-binding activity in response to doxorubicin. To provide a valid clinical correlate, HT1080 human fibrosarcoma cells were transfected with small interference RNA specific for IKKα or IKKβ and then subsequently treated with doxorubicin. Knockdown of IKKα severely impaired the ability of doxorubicin to initiate NF-κB DNA-binding activity. However, a decrease in either IKKα or IKKβ resulted in decreased phosphorylation of p65 in response to doxorubicin. The inhibition of doxorubicin-induced NF-κB activation by the knockdown of either catalytic subunit resulted in increased cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase and increased apoptosis when compared with doxorubicin alone. The results of this study validate current approaches aimed at NF-κB inhibition to improve clinical therapies. Moreover, we show that IKKα plays a critical role in NF-κB-mediated chemoresistance in response to doxorubicin and may serve as a potential target in combinational strategies to improve chemotherapeutic response. [Mol Cancer Ther 2008;7(7):1827–35]
Natural BH3 mimetic (-)-gossypol chemosensitizes human prostate cancer via Bcl-xL inhibition accompanied by increase of Puma and Noxa
Authors: Meng Yang , Tang Wenhua , Dai Yao , Wu Xiaoqing , Liu Meilan , Ji Qing , Ji Min , Pienta Kenneth , Lawrence Theodore , Xu Liang
Published: July 2008

Antiapoptotic members of the Bcl-2 family proteins are overexpressed in prostate cancer and are promising molecular targets for modulating chemoresistance of prostate cancer. (-)-Gossypol, a natural BH3 mimetic, is a small-molecule inhibitor of Bcl-2/Bcl-xL/Mcl-1 currently in phase II clinical trials as an adjuvant therapy for human prostate cancer. Our objective is to examine the chemosensitization potential of (-)-gossypol in prostate cancer and its molecular mechanisms of action. (-)-Gossypol inhibited cell growth and induced apoptosis through mitochondria pathway in human prostate cancer PC-3 cells and synergistically enhanced the antitumor activity of docetaxel both in vitro and in vivo in PC-3 xenograft model in nude mouse. (-)-Gossypol blocked the interactions of Bcl-xL with Bax or Bad in cancer cells by fluorescence resonance energy transfer assay and overcame the Bcl-xL protection of FL5.12 model cells on interleukin-3 withdrawal. Western blot and real-time PCR studies showed that a dose-dependent increase of the proapoptotic BH3-only proteins Noxa and Puma contributed to the cell death induced by (-)-gossypol and to the synergistic effects of (-)-gossypol and docetaxel. The small interfering RNA knockdown studies showed that Noxa and Puma are required in the (-)-gossypol-induced cell death. Taken together, these data suggest that (-)-gossypol exerts its antitumor activity through inhibition of the antiapoptotic protein Bcl-xL accompanied by an increase of proapoptotic Noxa and Puma. (-)-Gossypol significantly enhances the antitumor activity of chemotherapy in vitro and in vivo, representing a promising new regime for the treatment of human hormone-refractory prostate cancer with Bcl-2/Bcl-xL/Mcl-1 overexpression. [Mol Cancer Ther 2008;7(7):2192–202]
Destabilization of ERBB2 Transcripts by Targeting 3′ Untranslated Region Messenger RNA Associated HuR and Histone Deacetylase-6
Authors: Scott Gary K. , Marx Corina , Berger Crystal E. , Saunders Laura R. , Verdin Eric , Schäfer Stefan , Jung Manfred , Benz Christopher C.
Published: July 2008

In addition to repressing ERBB2 promoter function, histone deacetylase (HDAC) inhibitors induce the accelerated decay of mature ERBB2 transcripts; the mechanism mediating this transcript destabilization is unknown but depends on the 3′ untranslated region (UTR) of ERBB2 mRNA. Using ERBB2-overexpressing human breast cancer cells (SKBR3), the mRNA stability factor HuR was shown to support ERBB2 transcript integrity, bind and endogenously associate with a conserved U-rich element within the ERBB2 transcript 3′ UTR, coimmunoprecipitate with RNA-associated HDAC activity, and colocalize with HDAC6. HDAC6 also coimmunoprecipitates with HuR in an RNA-dependent manner and within 6 hours of exposure to a pan-HDAC inhibitor dose, that does not significantly alter cytosolic HuR levels or HuR binding to ERBB2 mRNA. Cellular ERBB2 transcript levels decline while remaining physically associated with HDAC6. Knockdown of HDAC6 protein by small interfering RNA partially suppressed the ERBB2 transcript decay induced by either pan-HDAC or HDAC6-selective enzymatic inhibitors. Three novel hydroxamates, ST71, ST17, and ST80 were synthesized and shown to inhibit HDAC6 with 14-fold to 31-fold greater selectivity over their binding and inhibition of HDAC1. Unlike more potent pan-HDAC inhibitors, these HDAC6-selective inhibitors produced dose-dependent growth arrest of ERBB2-overexpressing breast cancer cells by accelerating the decay of mature ERBB2 mRNA without repressing ERBB2 promoter function. In sum, these findings point to the therapeutic potential of HuR and HDAC6-selective inhibitors, contrasting ERBB2 stability effects induced by HDAC6 enzymatic inhibition and HDAC6 protein knockdown, and show that ERBB2 transcript stability mechanisms include exploitable targets for the development of novel anticancer therapies. (Mol Cancer Res 2008;6(7):1250–8)
Tumor-Derived Extracellular Mutations of PTPRT/PTPρ Are Defective in Cell Adhesion
Authors: Yu Jianshi , Becka Scott , Zhang Peng , Zhang Xiaodong , Brady-Kalnay Susann M. , Wang Zhenghe
Published: July 2008

Receptor protein tyrosine phosphatase T (PTPRT/PTPρ) is frequently mutated in human cancers including colon, lung, gastric, and skin cancers. More than half of the identified tumor-derived mutations are located in the extracellular part of PTPρ. However, the functional significance of those extracellular domain mutations remains to be defined. Here we report that the extracellular domain of PTPρ mediates homophilic cell-cell aggregation. This homophilic interaction is very specific because PTPρ does not interact with its closest homologue, PTPμ, in a cell aggregation assay. We further showed that all five tumor-derived mutations located in the NH2-terminal MAM and immunoglobulin domains impair, to varying extents, their ability to form cell aggregates, indicating that those mutations are loss-of-function mutations. Our results suggest that PTPρ may play an important role in cell-cell adhesion and that mutational inactivation of this phosphatase could promote tumor migration and metastasis. (Mol Cancer Res 2008;6(7):1106–13)
Transforming Growth Factor-β–Mediated Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand Expression and Apoptosis in Hepatoma Cells Requires Functional Cooperation between Smad Proteins and Activator Protein-1
Authors: Herzer Kerstin , Grosse-Wilde Anne , Krammer Peter H. , Galle Peter R. , Kanzler Stephan
Published: July 2008

Transforming growth factor-β (TGF-β) has been shown to induce apoptotic cell death in normal and transformed hepatocytes. We recently identified tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as an important mediator of TGF-β–induced apoptosis in hepatoma cells. In this study, we have further explored the mechanism by which TGF-β up-regulates TRAIL expression. The 5′-flanking region of the TRAIL gene was isolated and characterized. Deletion mutants of the 5′-untranslated region of the TRAIL gene revealed a region comprising nucleotides −1950 to −1100 responsible for TRAIL induction following treatment with TGF-β. Within this region, we have identified an activator protein-1 (AP-1) site indispensable for TGF-β–mediated induction of TRAIL. Activation of this AP-1 site is mediated by a JunD·FosB heterodimer. Expression of DNSmad4, DNJunD, or DNFosB significantly impairs TGF-β–mediated activation of the TRAIL promoter. Furthermore, with tRNA interference targeting Smad4, junD, FosB, we could abolish TRAIL expression and, subsequently, TGF-β–induced TRAIL-mediated apoptosis in hepatoma cells. Our results reveal a new AP-1 site within the TRAIL promoter functionally involved in TGF-β–induced TRAIL expression and apoptosis in hepatomas and thus provide evidence for the underlying mechanism by which TGF-β might regulate cell death in liver cancer. (Mol Cancer Res 2008;6(7):1169–77)
The Pak4 Protein Kinase Plays a Key Role in Cell Survival and Tumorigenesis in Athymic Mice
Authors: Liu Yingying , Xiao Hang , Tian Yanmei , Nekrasova Tanya , Hao Xingpei , Lee Hong Jin , Suh Nanjoo , Yang Chung S. , Minden Audrey
Published: July 2008

Pak4 is a member of the B group of p21-activated (Pak) kinases, originally identified as an effector protein for Cdc42. Although Pak4 is expressed at low levels in most adult tissues, it is highly overexpressed in tumor cell lines. Here, we show that Pak4 is also overexpressed in primary tumors, including colon, esophageal, and mammary tumors. Overexpression of Pak4 also leads to tumor formation in athymic mice, whereas deletion of Pak4 inhibits tumorigenesis. Although a constitutively active Pak4 mutant was previously shown to promote oncogenic transformation in cultured cells, our results are the first to show that Pak4 also promotes tumorigenesis in experimental animals. Furthermore, these results show for the first time that not only constitutively active Pak4, but also wild-type Pak4, is transforming, when experimental animals are used. These results are highly significant because wild-type Pak4, rather than activated Pak4, is overexpressed in tumor cells. Our results suggest that overexpression or activation of Pak4 is a key step in oncogenic transformation, due to its ability to promote cell survival and subsequent uncontrolled proliferation. The finding that Pak4 is up-regulated in so many types of cancers indicates that Pak4 may play a vital role in a wide range of different types of cancer. This makes it an attractive candidate for drug therapy for different types of cancer. (Mol Cancer Res 2008;6(7):1215–24)
Modulation of the Cyclin-Dependent Kinase Inhibitor p21WAF1/Cip1 Gene by Zac1 through the Antagonistic Regulators p53 and Histone Deacetylase 1 in HeLa Cells
Authors: Liu Pei-Yao , Chan James Yi-Hsin , Lin Hsiu-Chen , Wang Sung-Ling , Liu Shu-Ting , Ho Ching-Liang , Chang Li-Chien , Huang Shih-Ming
Published: July 2008

Zac1 is a novel seven–zinc finger protein which possesses the ability to bind specifically to GC-rich DNA elements. Zac1 not only promotes apoptosis and cell cycle arrest but also acts as a transcriptional cofactor for p53 and a number of nuclear receptors. Our previous study indicated that the enhancement of p53 activity by Zac1 is much more pronounced in HeLa cells compared with other cell lines tested. This phenomenon might be due to the coactivator effect of Zac1 on p53 and the ability of Zac1 to reverse E6 inhibition of p53. In the present study, we showed that Zac1 acted synergistically with either p53 or a histone deacetylase inhibitor, trichostatin A, to enhance p21WAF1/Cip1 promoter activity. We showed that Zac1 physically interacted with some nuclear receptor corepressors such as histone deacetylase 1 (HDAC1) and mSin3a, and the induction of p21WAF1/Cip1 gene and protein by Zac1 was suppressed by either overexpressing HDAC1 or its deacetylase-dead mutant. In addition, our data suggest that trichostatin A–induced p21WAF1/Cip1 protein expression might be mediated through a p53-independent and HDAC deacetylase–independent pathway. Taken together, our data suggest that Zac1 might be involved in regulating the p21WAF1/Cip1 gene and protein expression through its protein-protein interaction with p53 and HDAC1 in HeLa cells. (Mol Cancer Res 2008;6(7):1204–14)
Positive Development in Adolescence: The Development and Role of Intentional Self-Regulation
Authors: Gestsdottir Steinunn , Lerner Richard M.
Published: July 2008

Adolescence is a period of marked change in the person’s cognitive, physical, psychological, and social development and in the individual’s relations with the people and institutions of the social world. These changes place adaptational demands on adolescents, ones involving relations between their actions upon the context and the action of the context on them, a bidirectional process that has been labeled developmental regulation. The attributes and means through which the adolescent contributes to such regulation may be termed self-regulation. This article differentiates between organismic and intentional self-regulation and examines the development of intentional self-regulation in adolescence, and the individual and contextual contributions to its development. The model of Selection, Optimization, and Compensation, developed by Paul Baltes, Margaret Baltes, and Alexandra Freund, is used as a means to conceptualize and index intentional self-regulation in adolescence. The relation between intentional self-regulation and positive development of youth is examined.
Parasites of Urological Importance
Authors: Kehinde Elijah O. , Anim Jehoram T. , Hira Parsotam R.
Published: July 2008

With the world increasingly becoming a global village, transnational and transcontinental migration has become the order of the day. It is expected that migrants will take with them some diseases (including parasites) which are normally endemic in their countries of origin, to their host countries. Similarly, environmental changes that result from development of water resources, global warming, growth and migration of population can facilitate the spread of parasites. In this review we describe the epidemiology, presentation, diagnosis and treatment options of parasites that urologists may encounter. Notably among these parasites are Schistosoma haematobium, Echinococcus granulosus, Wuchereria bancrofti and Onchocerca volvulus.
Growth Hormone Inhibitors in Prostate Cancer: A Systematic Analysis
Authors: Schmid Hans-Peter , Gregorin Joel , Altwein Jens E.
Published: July 2008

Objective: Despite initial therapeutic success through androgen ablation in patients with advanced prostate cancer, the vast majority progress to androgen independence. Somatostatin (SST) analogs are a viable therapeutic modality before resorting to chemotherapy or immunotherapy. Their mechanism of action is related to a reduction in the IGF-1 (survival factor, reaction on neuroendocrine cells) appearing incrementally after long-term androgen deprivation and a possible suppression of GnRH receptors in prostate cancer following exposure to LHRH agonists. Methods: The computerized databases Medline, NCBI and OMIM were searched for the terms, somatostatin and prostate cancer, in parallel with printed bibliographic references. Forty-two studies were included and 267 patients with androgen-independent prostate cancer (AIPC) who were treated with SST analogs alone or in combination with other medications, e.g. dexamethasone, were analyzed. Results: In 42 studies with 267 AIPC patients, SST analogs were found to be effective, particularly when combined with estrogens or corticosteroids. The side effects are mild and related to the gastrointestinal tract. Conclusions: It would be interesting to study SST analogs in randomized trials including patients with well-defined AIPC. Whether SST analogs could be given earlier during sequential hormonal therapy remains to be studied.
Personal Characteristics of Enuretic Children: An Epidemiological Study from South-East Europe
Authors: Inan Mustafa , Tokuc Burcu , Aydiner Cagatay Y. , Aksu Burhan , Oner Naci , Basaran Umit Nusret
Published: July 2008

Introduction: This study examined the personal characteristics of enuretic children and investigated the risk factors of nocturnal enuresis among schoolchildren. Methods: It was a cross-sectional and descriptive questionnaire study and 2,000 children were stratified according to school population, age and gender. The questionnaire was designed for parents to collect information about the prevalence and associated factors as well. Results: Nocturnal enuresis was reported in 159 cases (9.8%). The parameters of bladder control after 2 years of age, urination more than 5 times a day, urinary infection history, history of psychological or physical trauma, siblings with health problems, large family size, lack of a private bedroom, and constipation were more frequent in enuretics (p < 0.05). The parameters of having fecal incontinence, parents and siblings with nocturnal enuresis, low educational level of the mother and poor school performance seem to be risk factors for nocturnal enuresis. However, the parental concern level was high, approximately half of the enuretic children did not visit a physician for management of the problem. Conclusion: Nocturnal enuresis could be a multifactorial problem originating from bladder dysfunction, deranged sleep patterns and psychological and hereditary predisposition. Hereditary disposition and having fecal incontinence may be important risk factors for enuresis.
Differential Impact of Lower Urinary Tract Symptoms on Generic and Disease-Specific Quality of Life in Men and Women
Authors: Araki Isao , Tsuchida Takayuki , Nomura Teruhisa , Fukasawa Mizuya , Takihana Yoshio , Koyama Nobuyuki , Takeda Masayuki
Published: July 2008

Introduction: We investigated how generic and disease-specific measures differ in estimating the quality of life (QoL) impact of lower urinary tract symptoms (LUTS). Materials and Methods: A total of 172 men and 67 women ≧40 years old who attended the public lectures completed the questionnaire comprising the International Prostate Symptom Score, benign prostatic hyperplasia impact index and SF-36 Health Survey. The multiple regression analysis was performed to evaluate the QoL impact of LUTS. Results: Both storage and voiding symptoms showed significant correlations with disease-specific QoL. Among men, voiding symptom correlated more closely with disease-specific QoL than storage symptom did, and this finding was reversed among women. Storage but not voiding symptoms showed a significant correlation with generic QoL. Among men, storage symptom correlated more closely with mental health than physical health, and the reversed finding was obtained among women. Generic QoL, especially physical health, was significantly influenced by some comorbid diseases, but disease-specific QoL was not. Conclusions: The QoL impact of LUTS was differentially estimated by disease-specific and generic measures with sex differences.
Efficacy of Doxazosin in the Treatment of Acute Urinary Retention due to Benign Prostate Hyperplasia
Authors: Prieto Luis , Romero Jesús , López Cristóbal , Ortiz Manuel , Pacheco Juan Jose
Published: July 2008

Objective: To evaluate the efficacy of modified-release doxazosin 4 mg in the treatment of patients with acute urinary retention (AUR) due to benign prostate gland hyperplasia (BPH). An evaluation is made of the number of patients recovering spontaneous micturition after catheter removal, micturition quality, and the number of patients suffering new AUR episodes or who require surgery in the 2 years following the first episode. Patients and Methods: A randomized, controlled study in males with AUR secondary to BPH. Two groups are formed, administering modified-release doxazosin 4 mg to patients born in even-numbered years, once a day in the morning. Those born in odd-numbered years receive no medication. The catheter is withdrawn 1 month later. Flowmetry is performed, with determination of ultrasonographic postmicturition retention at withdrawal, and after 6, 12 and 24 months. Results: Of the 65 patients included, 47 proved evaluable, and 46 complied with treatment (with exclusion of 1 case due to hypotension). Of the 22 patients treated with doxazosin, 15 (68.86%) presented AUR after 2 years, while 7 (31.2%) showed spontaneous micturition. Of the 24 patients treated with bladder catheterization in the absence of medication, 16 (66.6%) presented AUR after the same period of time, while 8 (33.3%) showed spontaneous micturition. There were no statistically significant differences between the treated and untreated subjects in terms of drug efficacy. Residual flow parameters are described in the population with spontaneous micturition in each stage of the study. Conclusion: In our series, treatment with the α-blocker doxazosin (4 mg, modified-release formulation), added to bladder catheterization, showed no increased efficacy in AUR treatment versus catheterization alone. Two years after the urinary retention episode, 31.2% of the patients treated with modified-release doxazosin 4 mg, and 33.3% of those with a bladder catheter only were seen to maintain spontaneous micturition.
Laparoscopic Management of Atypical Ureteropelvic Junction Obstruction: Alternative and Simple Techniques for Complex Situations
Authors: Kumar Santosh , Pandya Saurabh , Acharya Naveenchandra , Agarwal Mayank , Mandal Arup K. , Singh Shrawan K.
Published: July 2008

Purpose: We describe novel and simple techniques for management of cases of atypical and complex ureteropelvic junction (UPJ) obstruction. Material and Methods: Three cases of atypical UPJ obstruction were operated laparoscopically. Calicovesicostomy, pyelovesicostomy and ureteropyelostomy were performed laparoscopically as per the merits of each case. The 4-port technique was followed for calicovesicostomy and pyelovesicostomy (two 10-mm ports, one each at the umbilicus and lateral border of ipsilateral rectus and two 5-mm ports, one each at the lateral border of the contralateral rectus and midway between umbilicus and symphysis pubis). Both anastomoses were stented with a suprapubically placed Foley catheter. Laparoscopic ureteropyelostomy was done with port sites similar to standard laparoscopic pyeloplasty. Two double-J stents were placed, one in each moiety. Results: Mean operating time was 180 min and intraoperative blood loss was negligible. There were no intraoperative complications. The patients recovered well from the surgery. Postoperative nephrostograms confirmed anastomotic patency and good drainage. On follow-up, patients are doing well and asymptomatic. Patients with calicovesicostomy and pyelovesicostomy were advised double voiding. Conclusions: In select cases of giant hydronephrotic kidneys, anastomosis of the bladder with the most dependent part of pelvicalyceal system ensures adequate drainage. In UPJ obstruction with ureteral duplication, ureteropyelostomy with two double-J stents can be performed with good functional results. Laparoscopic performance of these procedures is feasible and simple.
In vitro Effect of Amikacin on Rat and Human Detrusor Muscle Contraction
Authors: Gardi M. , Nigro F. , Ragazzi E. , Volpe A. , Totaro A. , Sacco E. , Pinto F. , Bassi P.
Published: July 2008

Introduction: Normal and abnormal bladder contractions are principally mediated by acetylcholine released from postganglionic parasympathetic nerves. Since amikacin was reported to affect neurotransmission by a prejunctional mechanism, we investigated the effect of amikacin on isolated detrusor smooth muscle contraction to further evaluate its potential relaxant properties. Materials and Methods: Detrusor smooth muscle obtained from 15 rats and 8 patients undergoing surgery were studied through measurement of isometric muscular contraction induced with electrical field stimulation (EFS) (10–60 Hz), carbachol (10–7 to 10–3M) and nicotine (10–7 to 10–3M) in the presence or absence of 1 mM amikacin in a low-Ca medium. Results: Amikacin (1 mM) significantly reduced EFS-induced contraction of isolated rat and human detrusor muscle by 33 ± 6.57% (p < 0.005) and 40 ± 1.14% (p < 0.001), respectively. Contraction was restored after addition of calcium chloride (1 mM). The effect of amikacin was comparable to that of magnesium ions. Rat and human detrusor contractile response to nicotine was inhibited by 70 ± 8.27% (p < 0.001) and 64 ± 14.09% (p < 0.01) after the addition of amikacin (1 mM), while no significant effect was observed on carbachol-induced stimulation. Conclusion: Amikacin significantly inhibited detrusor contraction evoked by prejunctional stimulation in vitro, suggesting a depressant effect on autonomic neurotransmission in urinary bladder.
Effects of Partial Bladder Outlet Obstruction on Contraction and Relaxation Response of Rabbit Corpus Cavernosum
Authors: Demir Omer , Esen Emre Cem , Murat Nergis , Aslan Guven , Gidener Sedef
Published: July 2008

It has been well established that erectile dysfunction (ED) is a common incident in patients with benign prostate hyperplasia. Animal models have been described to investigate the relationship between bladder obstruction and ED. In this study, we aimed to investigate whether partial bladder outlet obstruction (PBOO) induces changes in the contraction and relaxation response of corpus cavernosum smooth muscle (CCSM) of the penis in the rabbit model. Partial bladder obstruction was performed in rabbits as previously described. After 2 and 4 weeks of follow-up, control, sham-operated (2- and 4-week duration) and partial bladder outlet obstructed (obstruction of 2- and 4-week duration) rabbits were sacrificed and their bladder masses determined. Then CCSM tissue was obtained. Contraction responses induced by 124 mM KCl, phenylephrine (10–6 to 10–4M) and relaxation responses induced by doxazosin (10–7 to 10–5M) in CCSM of rabbits were determined. The obtained contraction and relaxation responses of all groups were compared. Bladder weight was significantly higher in PBOO groups than in control and sham-operated rabbits. Contraction responses induced by KCl and phenylephrine were statistically enhanced in the 4-week PBOO groups than controls. However, there was no statistically significant difference in any KCl, phenylephrine and doxazosin responses between 2- and 4-week sham-operated and PBOO groups. The rabbit model of PBOO described for the studies which examine bladder responses is useful for creating bladder outlet obstruction. However, this model is not suitable for the investigation of outlet obstruction-related ED.