bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 4970: Complex regulation of RIP140 gene expression by E2F transcription factors
Authors: Docquier Aurelie , Harmand Pierre-Olivier , Fritsch Samuel , Badia Eric , Fajas Lluis , Augereau Patrick , Cavailles Vincent 
Published: February 2011

Abstract
We recently showed that RIP140 (Receptor Interacting protein of 140 kDa), a regulator of nuclear receptor activity, was involved in the control of cell proliferation and able to repress E2F1 activity. We now demonstrate that RIP140 and E2F1 comprise a novel transcriptional regulatory loop. We first observed that RIP140 mRNA levels increased during the G1/S and G2/M transitions and were reduced in tissues from E2F1 null mice. Furthermore, we identified the RIP140 gene as a transcriptional target of E2F1, showing, by transient transfection, that overexpression of E2F1/DP1 strongly increased transcription of the RIP140 promoter. Bioinformatic analysis identified several binding sites for E2Fs in the proximal promoter region and we evidenced the direct binding of E2F1/DP1 on these sequences by gel shift analysis. However, site directed mutagenesis of these elements only modestly affected transactivation of the RIP140 promoter by E2F1/DP1, thus suggesting an indirect recruitment of E2Fs on the promoter. This was strengthened by the observation that overexpression of E2F1, 2 or 3 alone was very potent in increasing transcription from the RIP140 promoter. Moreover, overexpression of DP1 produced a negative effect on this regulation which was also strongly repressed by RIP140 itself. Altogether, these results revealed a complex control loop between E2Fs and RIP140 and the molecular mechanisms underlying these atypical regulations are currently under investigation.
Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4970.
Abstract 4978: FOXP3 up-regulates p21 expression in breast cancer: Evidence for tumor suppressor
Authors: Liu Runhua , Wang Lizhong , Katoh Hiroto , Zheng Pan , Liu Yang 
Published: February 2011

Abstract
FOXP3 is the first X-linked breast cancer suppressor gene that works at least in part by repression of oncogenes, including HER-2 and SKP2. Since FOXP3 is also known as a transcription activator, we investigated the possibility that FOXP3 may induce expression of tumor suppressor genes. p21 loss has been implicated in conferring oncogenic activity to known tumor suppressor gene KLF4 and cancer drug tamoxifen. Regulators of p21, therefore, play critical roles in tumorigenesis. Here, we report that X-linked tumor suppressor FOXP3 is essential for p21 expression in normal epithelia and that lack of FOXP3 is associated with p21 down-regulation in breast cancer samples. Among 62 primary breast cancer samples tested, a strong association between FOXP3 down-regulation and lack of p21 was observed. Moreover, siRNA silencing of FOXP3 in primary human mammary epithelial cells leads to a dramatic reduction in expression of p21, which demonstrates an important role of FOXP3 in maintaining expression of p21 in normal breast epithelial cells. In breast cancer cell line MCF-7, an inducible expression of FOXP3 is associated with induction of p21. Since silencing p21 reduced the efficacy of FOXP3-mediated growth inhibition, the induced expression of p21 contributes to growth inhibition by FOXP3. A specific FOXP3 binding site in the intron 1, which is associated with acetylated histone H3, is essential for p21 induction by FOXP3. FOXP3 specifically inhibited binding of histone deacetylase 2 (HDAC2) and HDAC4 to the site and increased local histone H3 acetylation. Short hairpin RNA silencing of either HDAC2 or HDAC4 is sufficient to induce p21 expression. Our data provides a novel mechanism for transcription activation by FOXP3 and a genetic mechanism for lack of p21 in a large proportion of breast cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4978.
Abstract 4979: The role of Tel in repression of BCL-XL transcription in tumor cells
Authors: Cao Xiaobo , Peddaboina Chander , Jupiter Daniel , Zhang Lidong , Littlejohn James , Rascoe Philip , Smythe Roy 
Published: February 2011

Abstract
Study of Bcl-xl and hepatocyte growth factor (HGF) receptor c-Met demonstrates that ETS transcription factors influence the transcriptional control of Bcl-xl in multiple tumors. The phosphorylation of Tel, a transcriptional repressor in the ETS family, by activated c-Met is required to increase Bcl-xl transcription in addition to activation of ETS2, a transcriptional activator.
Our data indicate that stimulation by HGF causes the activation of ERK and leads to the nuclear export of Tel. In order to determine whether ERK is responsible for the phosphorylation of Tel after HGF stimulation, physical interaction between Tel and ERK was detected using I.P. (Tel)-western blotting (ERK). To determine if blocking MAP kinase could prevent Tel's phosphorylation after HGF exposure, we again used I.P. Western to compare the phosphorylation of Tel under specific ERK kinase inhibitors, after HGF exposure, to the phosphorylation of Tel in the absence of inhibitors, after HGF exposure. A His-Tel 213mutant (phosphorylation sites mutants) was created. The Tel 213 mutant did not undergo phosphorylation induced by c-Met activation, as demonstrated by I.P. Western blot. Nuclear localization of mutated His-Tel was detected under HGF/EGF exposure via fluorescent microscopy using FITC labeled anti-his antibody, indicating that phosphorylation of Tel is also required for nuclear export. A luciferase reporter assay shows that the transient expression of Tel 213 mutant in cancer cell lines results in further repression of Bcl-xl promoter activity. Indeed, Tel 213's repressive function is independent of c-Met stimulation, as determined by comparing with wild type Tel cDNA transfected cells. Consequently, Tel 213 transfection results in much stronger reduction in Bcl-xl mRNA and protein expression levels in the presence of HGF, as compared to transfection with wild-type Tel cDNAs in the presence of HGF. Furthermore, a CHIP assay demonstrates that the activation of c-Met reduced the binding of wild-type Tel to the Bcl-xl promoter, while the binding of Tel 213 to bcl-xl promoter was not affected. Finally, transfection of Tel 213 leads to increased cell proliferation inhibition and apoptosis.
Taken together, these findings are supportive of a role for Tel, through a c-Met aixs, as an inhibitor of Bcl-xl transcription.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4979.
Abstract 4983: Galectin-3 regulates p21 expression through negatively regulating its degradation
Authors: Wang Yi , Nangia-Makker Pratima , Raz Avraham 
Published: February 2011

Abstract
Galectin-3 (Gal-3), a carbohydrate-binding protein, has been demonstrated to be involved in multiple biological events such as cell adhesion, cell migration, cell proliferation, apoptosis and so on. p21, originally described as a inhibitor of cyclin-dependent kinases (CDK), has been shown to have anti-apoptotic activity as well as regulation of cell proliferation. Since both of these two proteins play important roles in cancer and some of their functions overlap, we assumed that there may be some relationship between Gal-3 and p21. Here, we first reported that Gal-3 positively regulates p21 expression in cancer cells, and this effect works at protein degradation level. Over-expression of Gal-3 in Gal-3 null human prostate cancer cell line LNCap and breast cancer cell line BT549 inhibited p21 degradation. Moreover, Gal-3 knockdown in Gal-3 expressing prostate cancer cell line DU145 potentiated p21 degradation, suggesting that Gal-3 negatively regulates p21 degradation in cancer cells. Furthermore, our data showed that Gal-3 negatively regulated proteasomal turnover of p21 in an ubiquitin-dependent way. In this study, we also showed for the first time the direct interaction between Gal-3 and p21. This study suggested that p21 may serve as the downstream molecule of Gal-3 signal transduction pathway to mediate some of Gal-3 functions, and it helps to understand further the mechanisms for Gal-3 functions.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4983.
Abstract 4997: The expression PHLPP is regulated by the mTOR-P70S6K signaling pathway
Authors: Liu Jianyu , Gao Tianyan 
Published: February 2011

Abstract
PHLPP is a novel family of protein phosphatases serving as negative regulators of Akt by directly dephosphorylating the kinase. Our previous studies have indicated a tumor suppressor role of PHLPP in human colon cancer. However, the regulation of PHLPP expression in cancer cells remains unknown. Here, we report that the expression of PHLPP protein is regulated by the mTOR-p70S6K pathway in colon and breast cancer cell lines. Treating cells with rapamycin, an inhibitor of mTOR, induces a marked decrease of PHLPP protein expression, and this rapamycin-mediated down-regulation of PHLPP expression is blocked by overexpression of a constitutively active mutant of p70S6K. Stable knockdown of TSC2, a negative regulator of mTOR, using lentiviral-based RNAi results in an increase of PHLPP expression, while knockdown of mTOR decreases the expression level of PHLPP protein. In addition, knockdown of 4E-BP1, a translation initiation inhibitor and a downstream effector of mTOR, results in an increase of PHLPP expression and resistance to rapamycin or Torin1 induced decrease of PHLPP expression in cells. Furthermore, amino acid starvation of cells, which inactivate the mTOR signaling, decreases PHLPP expression, and this is reversed by resupplying amino acids. Control experiments show that the rate of PHLPP degradation was not alerted significantly by rapamycin treatment or knockdown of TSC2. The real-time RT-PCR analysis reveals that the mRNA level of PHLPP remains constant in the TSC2 and mTOR knockdown or rapamycin treated cells. Taken together, these results suggest that the translation of PHLPP proteins is controlled by mTOR. Our studies identify a compensatory feedback regulation of Akt signaling in which the activation of Akt is negatively regulated by up-regulation of PHLPP protein in an mTOR-dependent manner.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4997.
Abstract 4999: Glutamate receptors in cancer: Stable expression of GluR6 induces growth arrest and senescence in hepatocellular carcinoma HCC 7703 cells
Authors: Kaur Gurpreet , Pilidis Konstantinos G. , Zhawar Vikramjit K. , Kaur Gursurinder P. , Athwal Raghbir S. 
Published: February 2011

Abstract
Applying a functional strategy, we identified a gene, SEN6A, located at 6q21, which restores senescence in breast tumor cells. Human genome database search identified SEN6A as GluR6, a kainate type - ionotropic glutamate receptor gene. Kainate receptors constitute a family of ionotropic glutamate receptors that plays a role in the rapid synaptic transmission in the central nervous system. Glutamate receptors have been implicated in several pathophysiological conditions including Epilepsy, Schizophrenia and Parkinson's disease. We cloned the GluR6 gene by RT-PCR and investigated the structure, splicing pattern and its role in the cell senescence and cancer. We show that GluR6A, a splice variant is specifically expressed in brain, and four other variants; namely, GluR6B, GluR6C, GluR6D and GluR6E are expressed in other tissues and fibroblast cell lines. Genomic analysis and cloning of the sequence preceding the transcribed region led to the identification of two tissue specific promoters designated as neuronal promoter Pn and non-neuronal promoter Pnn. GluR6 is expressed in most tissues and its expression is elevated in late passage cells, relative to young human cells. The gene is either turned off or expressed at a reduced level in a large number of tumor cell lines. The chromosomal location of GluR6 at 6q21, a LOH hot spot in multiple cancers, points to its potential role in the etiology of cancer. The analysis for mutations in 22 cancer cell lines revealed a point mutation in exon 15 and deletion of exon 6 in two hepatoma cell lines.
Open reading frame of GluR6 was cloned in a retroviral expression vector, in frame with EGFP tag, where EGFP is added after the signal peptide. In this vector GluR6-EGFP gene is expressed as a single transcript, from a CMV promoter, along with puromycin gene for selection. Ecotopic expression of GluR6 (variants A-E) induces growth arrest and senescence in hepatoma HCC7703 cells, and induce premature senescence in normal fibroblasts. Clones of GluR6 transfer cells display doubling time of 72-96 hours that gradually increases to 3-4 days ending in complete growth arrest and senescence. In contrast the transfer of empty vector or a construct carrying truncated GluR6 gene did not affect the growth of HCC7703 or normal cells. These result show that GluR6 is involved in the cascade of signaling circuits that govern cell growth and differentiation. Future studies are designed to investigate signaling pathways responsive to the expression of GluR6 gene.
Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4999.
Abstract 5000: Epigenetic de-silencing of Glutathione s-transferase pi by tumor suppressive maspin
Authors: Li Xiaohua , Heath Elisabeth , Sakr Wael A. , Sheng Shijie 
Published: February 2011

Abstract
Abstract: Loss of expression of the GST pi isoform due to DNA hypermethylation-mediated epigenetic silencing is one of the most common molecular events in precancerous and cancerous lesions of human prostate. Our previous studies demonstrated that tumor suppressive maspin, an endogenous inhibitor of histone deacetylase 1, could up-regulated GST activity and reduced reactive oxygen species (ROS) generation in response to oxidative stress treatment. We confirmed that maspin restored GST pi expression in maspin transfected prostate cancer cell line DU145. Conversely, maspin knocking down by siRNA in PC3 cells led to reduced GST pi expression. We further investigated the possibility that the epigenetic regulation by DNA-methylation and histone deacetylation were coupled dynamic processes that HDAC inhibition by maspin alone was sufficient to reverse the DNA-methylation silencing effects. Using methylation-specific polymerase chain reaction (M-PCR), DNA demethylation in GST pi promoter was detected only in maspin-expressing cells. Chromatin immunoprecipitation (ChIP) assay showed that a significant higher level of acetylated histone 3 was associated with the GST pi promoter DNA complex. In the same DNA complex from maspin transfected cells, less DNA methylation transferase (DNMT1) and methyl-CpG-binding domain (MBD2/3) proteins were detected as compared to that from the mock control cells. It was noted that in DU145-derived transfected cells, maspin simultaneously restored GST pi expression and sensitized tumor cells to drug-induced apoptosis, while overexprssion of GST pi alone in LNCaP prostate cancer cells conferred resistance to oxidative stress in cell death, HIF-1α induction, and phosphorylation of histone 2A.X. These data suggest that, as an epithelial-specific HDAC1 inhibitor, maspin may function to maintain the epithelial tissue homeostasis through balancing the GST pi-dependent detoxification and HDAC1 inhibition-dependent apoptosis sensitivity.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5000.
Abstract 5023: Down-regulating interferon regulatory factor-1 by siRNA promotes endurance to fulvestrant in sensitive breast cancer cells partially via Ras/Raf/MEK/ERK pathway
Authors: Ning Yanxia , Riggins Rebecca B. , Shajahan Ayesha N. , Zwart Alan , Clarke Robert 
Published: February 2011

Abstract
AIM: Interferon Regulatory Factor 1 (IRF1) is a tumor suppressor gene that has an antitumor role in some cancers. In this study, we showed that reducing IRF1 expression by siRNA promotes resistance to Fulvestrant in MCF7/LCC1 cells at least partly by acting though the Ras/Raf/MEK/ERK pathway. METHODS: After transfection with IRF1 siRNA by Amaxa Nuclofection, the MCF7/LCC1 cells were treated with 100 nM Fulvestrant for 2 days for monitoring gene expression, and for 3 and 6 days for apoptosis and cell proliferation assays, respectively. Five μM U0126 or 10 μM PD98059, the inhibitors of MEK, were used when necessary. Transactivation of IRF1, Bcl-2, Cyclin D1, and ERE were detected by luciferase assays after transfection with the appropriate reporter plasmid. Caspase 7, 8 and 9 activities were detected by cleavage of their respective substrates. RESULTS: After transfected with IRF1 siRNA, the mRNA and protein levels of IRF1 expression were greatly reduced in MCF7/LCC1 cells. Knocking-down IRF1 expression resulted in increased proliferation, increased S-phase ratio, and decreased apoptosis of MCF7/LCC1 cells compared to mock or control siRNA groups. mRNA and protein levels of Bcl-2, Bcl-w, Bcl-xL, Survivin and CyclinD1 were increased by IRF1 siRNA transfection. Luciferase assays showed that the Bcl-2 P2 (but not P1) promoter is inhibited by IRF1 siRNA transfection. At same time, the activities of Caspase 7 and 8 cannot be increased by Fulvestrant treatment after IRF1 siRNA transfection. Knocking down IRF1 expression partially restores Fulvestrant's inhibition of ERE-drive transcription. Total and phosphor-ER α expression were reduced by IRF1 siRNA transfection. Further, we found that the phosphor-ERK1/2 expression levels were increased by IRF1 siRNA transfection. Inhibition MEK with inhibitors could partially reverse the effect of IRF1 siRNA transfection on proliferation via inhibiting the effect of cell cycle other than apoptosis. Using the inhibitors has no effect on the expression of ER α and the transcriptional activity of ERE. CONCLUSIONS: Knocking down IRF1 expression promotes resistance to Fulvestrant in MCF/LCC1 breast cancer cells partially by increasing the expression of phosphor-ERK1/2. The reduced of ERα expression and increased transcriptional activity of ERE has also involved in the mechanism.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5023.
Abstract 5031: Combination inhibition of the FAK-p53 and MDM2-p53 interactions suppressed proliferation in mesothelioma
Authors: Ou Wenbin , Fletcher Jonathan A. 
Published: February 2011

Abstract
Mesothelioma is a chemotherapy-resistant neoplasm, as is evident in the dismal survival for patients with this asbestos-associated disease. Conventional chemotherapies and radiation therapy have only limited efficacy, and improved survival will require development of novel and more effective pharmacological interventions. Although p53 genomic mutations are uncommon in mesothelioma, we hypothesized that functional p53 inactivation (resulting from NF2-dysregulated FAK activation) might be a frequent event. Using proteomic methods, with tandem mass spectrometry analyses of mesotheliomas after double immuno-affinity purifications for p53 and phosphotyrosine, we find that FAK is consitutively activated in 10 of 10 mesothelioma cell lines and 9 of 9 mesothelioma surgical specimens, and associated with p53 in 6 of 6 mesothelioma cell lines. In four mesotheliomas with non-mutant p53, FAK silencing by lentiviral short hairpin RNA (shRNA) induced expression and phosphorylation of p53 at Ser15. However, FAK regulation of mesothelioma proliferation was not restricted to p53-dependent pathways, as demonstrated by immunoblots after FAK knockdown in JMN1B mesothelioma cells, which have mutant/inactivated p53, compared to MESO924, MESO257, MESO296, and MESO428 cells, which have nonmutant p53. Additive effects were obtained through a coordinated attack on p53, as demonstrated by immunoblots, cell viability and cell cycle analyses, showing that FAK knockdown and MDM2 inhibition (nutlin-3) induced greater p53 expression, cell apoptosis, anti-proliferative effects and cell cycle arrest, compared to either intervention alone. These findings highlight novel therapeutic opportunities in mesothelioma.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5031.
Abstract 5035: The MEK inhibitor AZD6244 is active in GNAQ mutant ocular melanoma cells
Authors: Ambrosini Grazia , Schwartz Gary K. 
Published: February 2011

Abstract
Uveal melanoma represents the most common intraocular malignancy in the United States. However, there are no effective treatments for this aggressive metastatic disease. While activating mutations in B-RAF are rare in ocular melanoma, oncogenic G protein alpha subunit q (GNAQ) mutations at codon 209 have been described in about 50% of uveal melanomas. Knock-down of GNAQ by siRNA inhibits p-ERK and the MEK inhibitor U0126 has been shown to inhibit growth of a GNAQ mutant cell line (Van Raamsdonk CD et al, Nature 2009). AZD6244 (ARRY-142886) is a MEK inhibitor now in clinical trials. Published phase I results have indicated clinical benefit in a patient with ocular melanoma (Adjei AA et al, J Clin Oncol. 2008). In view of this, we elected to test AZD6244 across a panel of ocular melanoma cell lines that differ in their GNAQ mutational status. Treatment with AZD4244 inhibited cell proliferation in a time- and dose-dependent manner, with IC50s in the 100-150nM range. This corresponded to the inhibition ERK phosphorylation and down-regulation of cyclin D1 in GNAQ mutant (both Q209L and P209L), but not in GNAQ wild-type cells. Over-expression of mutant GNAQ(Q209L) in wild type OCM290 cells, which are highly resistant to AZD6244, resulted in drug sensitization with inhibition of ERK phosphorylation. Depletion of GNAQ by siRNA in the GNAQ mutant cells resulted in inhibition of ERK phosphorylation and growth suppression. Interestingly, GNAQ depletion had no effect on ocular melanoma cells with wild type GNAQ or mutant B-RAF. We conclude that the GNAQ activating mutation in ocular melanoma can mediate sensitivity to AZD6244. This data provide a rationale for the clinical evaluation of AZD6244 in uveal melanoma.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5035.