bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 2037: Anti-miRNA-21 confers radiosensitivity through inhibition of PI3K/AKT pathway and enhancing autophagy
Authors: Gwak Ho-Shin , Kim Tae Hoon , Lee Seung Hoon , Yoo Heon , Park Jong Bae 
Published: February 2011

Abstract
Radiation is a core part of therapy for malignant glioma, which has been given after debulking surgery and prolonged patient's survival. However, the mass of glioma hardly shows response to radiation and frequently become radioresistant after the initial radiation. Among onco-microRNAs, microRNA-21 regulates expression of various molecules involved in anti-apoptosis, invasion, and metastasis in cancer. Yet, there has been known to the relationship between microRNA-21 and radioresistance of glioma. In this study, we investigate the effect of anti-mir-21 on radiosensitivity in glioblastoma and cervical cancer cell lines. Induction of mature microRNA-21 was confirmed by Nothern blotting after irradiation and the transfection of anti-mir-21 resulted in radiosenstivity on colony forming assay. The radiosensitive is thought to be the results of impairment of DNA repair in irradiated cancer cells, which is proved by γ-H2AX staining. In contrast to control group, a significant percentage of anti-mir-21 transfected cells retain DNA foci at 24 hours after irradiation. The suppression of radiation-activated PI3K/Akt pathway is proved on Western blot and thought to be one of the mechanisms for anti-mir-21 induced radiosensitization. Cell cycle analysis shows significant increase of G2/M phase arrest in anti-mir-21 treated cells compared to the control while subG1 population representing apoptotic cells reveals no significant difference between two groups. To investigate further the responsible cell death mechanism other than apoptosis, we measured the degree of autophagy in irradiated cells by both counting acid vesicular organelles using flow cytometry and Western blotting for LC-3 band. The autophagy is significantly increased in anti-mir-21 treated cells after radiation compared to mock treated cells.
We suggest that microRNA-21 is a pivotal regulator of mechanisms to evade radiation-induced cell death in cancer cell.
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 2037.
Abstract 2039: Hyaluronan-CD44 interaction with PKCε promotes oncogenic signaling by the stem cell marker, Nanog and the production of microRNA-21 leading to downregulation of the tumor suppressor protein, PDCD4, anti-apoptosis and chemotherapy resistance in breast tumor cells
Authors: Bourguignon Lilly Y. W , Spevak Christina C. , Wong Gabriel 
Published: February 2011

Abstract
Multidrug resistance and disease relapse is a challenging clinical problem in the treatment of breast cancer. In this study we investigated the hyaluronan (HA)-induced interaction between CD44 (a primary HA receptor) and protein kinase Cε (PKCε) which regulates a number of human breast tumor cell functions. Our results indicate that HA binding to CD44 promotes PKCε activation which, in turn, increases the phosphorylation of the stem cell marker, Nanog, in the breast tumor cell line, MCF-7. Phosphorylated Nanog is then translocated from the cytosol to the nucleus and becomes associated with RNase III DROSHA and the RNA helicase, p68. This process leads to microRNA-21 (miR-21) production, and a tumor suppressor protein [e.g., the Program Cell Death 4 (PDCD4)] reduction. All of these events contribute to upregulation of inhibitors of apoptosis proteins (IAPs, e.g., XIAP and survivin) and the multidrug resistant protein (MDR1)/P-glycoprotein (P-gp) resulting in anti-apoptosis and chemotherapy resistance.
Transfection of MCF-7 cells with PKCε or Nanog-specific small interfering RNAs (siRNAs) effectively blocks HA-mediated PKCε/Nanog signaling events, abrogates miR-21 production and increases PDCD4 expression/eIF4A binding. Subsequently, this PKCε/Nanog signaling inhibition causes IAP/MDR1 (P-gp) downregulation, apoptosis and chemosensitivity. To further evaluate the role of miR-21 in oncogenesis and chemoresistance, MCF-7 cells were also transfected with a specific anti-miR-21 inhibitor in order to silence miR-21 expression and inhibit its target functions. Our results indicate that anti-miR-21 inhibitor not only enhances PDCD4 expression/eIF4A binding, but also blocks HA/CD44-mediated tumor cell behaviors [e.g., IAP/MDR1 (P-gp) upregulation, anti-apoptosis and chemotherapy resistance] in MCF-7 cells. Taken together, these findings suggest that the HA-induced CD44 interaction with PKCε plays a pivotal role in Nanog signaling and miR-21 production leading to the tumor suppressor protein (PDCD4) downregulation, anti-apoptosis/survival and chemoresistance. Thus, this newly-discovered HA/CD44 signaling pathway should provide important drug targets for sensitizing tumor cell apoptosis and overcoming chemotherapy resistance in breast cancer cells.
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 2039.
Abstract 2040: Identification of microRNAs associated with tamoxifen resistance in breast cancer
Authors: Lau Lai-yee , Chan Kelvin Yuen-kwong , Khoo Ui-Soon 
Published: February 2011

Abstract
Tamoxifen is the most commonly used endocrine therapy for estrogen receptor-positive breast cancer patients. As an estrogen antagonist, tamoxifen competes for binding with estrogen receptor, thereby inhibiting estrogen-dependent gene transcription and tumor growth. However, some breast tumors become estrogen-independent and ultimately develop resistance to the treatment. The mechanisms underlying this transition in the control of cell proliferation remain unclear. Recent work has shown that aberrant expression of microRNAs has been frequently detected in breast cancer and some of which are associated with breast cancer metastasis, poor prognosis, suggesting an important role of microRNAs in breast cancer development and progression. Certain microRNAs negatively regulate AIB1/ACTR, ERα, HER2 and HER3 and deregulation of these genes are well documented to modulate the resistance to tamoxifen in breast cancer. Therefore, we hypothesized that deregulated microRNAs might confer the aberrant expression of their target genes and the development of tamoxifen resistance in breast cancer.
To identify microRNAs that might confer resistance to tamoxifen in breast cancer, we examined expression profiles of more than 600 microRNAs in a pair of tamoxifen-sensitive ZR75 and -resistant AK47 breast cancer cell lines using TaqMan Low Density Array (Applied Biosystems). Sixty-five microRNAs were identified substantially downmodulated in the tamoxifen-resistant cell line while 44 microRNAs were found to be upregulated. Consistent with others’ previous findings, our profiling results indicated that miR-221 and miR-222 were overexpressed in the tamoxifen-resistant breast cancer cells. Of the differentially expressed microRNAs, miR-449a and miR-449b were significantly downregulated in the resistant AK47 cells. miR-449a/b expression was also examined in 60 frozen breast tumors by TaqMan Individual MicroRNA Assay (Applied Biosystems). The expression of miR-449a/b was inversely correlated with tumor grade (miR-449a: OR=0.11, 95%CI=0.03-0.38, p&lt;0.001; miR-449b: OR=0.23, 95%CI=0.07-0.70, p=0.008) and strongly associated with estrogen receptor status of the tumor (miR-449a: OR=5.57, 95%CI=1.67-18.55, p=0.003; miR-449b: OR=5.0, 95%CI=1.51-16.56, p=0.006). Our results suggest that miR-449a/b may influence tamoxifen sensitivity in breast cancer cells. Further functional studies are being performed to investigate the regulatory roles of the microRNAs in the development of tamoxifen resistance in 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 2040.
Abstract 2041: PDGF inducible microRNAs regulate gene expression in cancer cells
Authors: Shao Minghai , Rossi Simona , Chelladurai Bhadrani , Ntukogu Obiageli , Ivan Mircea , Calin George , Matei Daniela 
Published: February 2011

Abstract
Background: Platelet derived growth factor (PDGF)-regulated signaling plays a critical role in oncogenesis. By binding to the PDGF receptors, the Akt, Src and MAPK pathways are activated to regulate genes expression and cellular physiological processes. There are subtle functional differences between the effects of specific PDGF ligands (e.g. AA, BB), which are incompletely understood. MicroRNA(miR)s are single-stranded, 21-23 nucleotide regulatory RNAs that repress target gene expression either by inhibiting protein translation or by promoting target mRNA degradation. The hypothesis tested in this study was that PDGFs regulate genes expression by modulating microRNAs level in cancer cells.
Methods: MicroRNA microarrays were performed to identify miR alterations after treatment of U118 glioblastoma cells with PDGF-AA and BB. Several time points were tested: 2, 6, 12, and 24 hour. Significance Analysis of Microarrays (SAM) was performed to compare expression level between different time points. Q-PCR was conducted to confirm the microarrays data. Pre-miR probe/miRCury LNA probe were transfected into cancer cells to over-express/knock down selected miRs. Western blots were used to detect miRs’ target proteins.
Results: Candidate PDGF-inducible/repressible miRs were identified based on significant change in expression level after AA/BB treatment (p-value &lt;0.01). Expression levels of 7 miRs were altered by PDGF AA and expression levels of 14 miRs were altered after PDGF BB treatment. By Q-PCR we showed that let 7d was repressed by PDGF-AA, but not by PDGF-BB in cancer cells (U118, C272 and U87) and in fibroblasts (WI38). Cyclin D1 is a known target of let7d. By overexpression and knock-down strategies we show that PDGF-AA induced cyclin D1 expression is mediated via repression of let7d. Q-PCR confirmed that miR-146b and miR-106b are inducible by PDGF-BB, but not by PDGF-AA in cancer cells (U118, C272 and U87) and in fibroblasts (WI38). MiR-146b induction by PDGF-BB is modulated via MAPK-dependent induction of Fos. A Fos binding element was identified in the promoter region of miR146b and Fos binding to this region in the presence of PDGF-BB was confirmed by chromatin immunoprecipitation. Several targets of miR146b are altered by PDGF in cancer cells.
Conclusions: Our data demonstrate for the first time that PDGF signaling regulates expression of several critical oncogenic miRs which in turn alter target gene expression and function.
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 2041.
Abstract 2043: Inhibition of cervical carcinoma cells proliferation by miR-34c
Authors: Lopez Jesus A. , Salas Luis M. Alvarez 
Published: February 2011

Abstract
MicroRNAs (miRNAs) play central roles in controlling cell proliferation, differentiation, and apoptosis. Aberrant miRNA expression is recognized as an important molecular mechanism for human carcinogenesis. Infection with high-risk human papillomaviruses (HPVs) is causally associated with the onset of cervical dysplasia including cancer. Although high-risk HPV infection leads to hyperproliferation and immortalization, it is insufficient to produce a fully transformed phenotype. High-risk HPV E6 proteins (i.e. HPV-16 and 18) inactivate and destroy P53 protein leading to a p53-null phenotype and the subsequent repression of the p53 effector network including pro-apoptotic proteins and cell cycle inhibitors. Microarray analyses in normal and tumor cervical cells have linked only a few miRNAs to cervical cancer. However, no miRNAs have been established in the malignant process that may follow a high-risk HPV infection. Here, we analyze the function of miR-34c (a p53 effector) in HPV-positive cells. Steady-state miR-34c levels are very low in both immortal and tumor HPV-positive cells. Over-expression of miR-34c in cervical carcinoma cells caused inhibition of cell proliferation and anchorage independent growth resulting in G2/M arrest and significant apoptosis. Interestingly, no effect was noticed in HPV-negative tumor cells and HPV-immortalized keratinocytes suggesting a differential regulatory pathway of mi-34c in HPV-positive tumor cells. Analyses of miR-34c potential targets showed no significant effect on BCL-2 levels although it produced MAP-2 down-regulation. These results suggest that activation of miR-34c in the absence of functional p53 may play an important role in proliferation and apoptosis of HPV-positive cervical tumor cells that could be used as therapeutic or diagnostic/prognostic tool for cervical cancer therapy.
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 2043.
Abstract 2046: The hepatic miR-200/Zeb module is perturbed in the male Fischer rat following short term treatment with a carcinogenic dose of Phenobarbital
Authors: Koufaris Costas , Wright Jayne , Currie Richard A. , Gooderham Nigel J. 
Published: February 2011

Abstract
Few studies have so far examined the role of microRNAs (miRNAs) in directing the adaptive or adverse responses of the liver following chemical carcinogen exposure. Nevertheless, significant evidence supports the importance of miRNAs in normal liver functioning and their dysregulation in diseased states.
In this study we chose to look at the effect of Phenobarbital, a prototype rodent non-genotoxic hepatocarcinogen, on liver miRNAs of the male Fischer rat. The animals were exposed to either a carcinogenic (1000 ppm) or two non-carcinogenic (50 and 500 ppm) dietary doses of Phenobarbital for up to 90 days. Microarrays and quantitative Real-time PCR were then used to profile liver miRNA expression.
Unsupervised hierarchical clustering separated the samples according to dose after 14 days, that is the carcinogenic dose of Phenobarbital resulted in a distinct miRNA profile. A number of miRNAs showed statistically significant changes in expression uniquely to the carcinogenic dose at 14 days. Prominent was miR-200b, which was specifically upregulated by the carcinogenic dose of Phenobarbital atfter 14 days, but not before then. Real-time PCR confirmed this upregulation of miR-200b and that it was maintained after 90 days exposure to Phenobarbital. Mir-200b is a member of the miR-200 family of miRNAs, which form part of a negative feedback loop with two protein targets: Zeb1 and Zeb2. Western blots confirmed that both proteins are downregulated specifically by the carcinogenic dose of Phenobarbital.
This study demonstrates that carcinogenic doses of Phenobarbital cause distinct effects on miRNA expression compared to non-carcinogenic doses, specifically an alteration in the miR-200/Zeb module was observed. Importantly, others have reported perturbation of this module in the liver of rats following carcinogenic treatments with acetoaminofluorine and choline-deficient L-amino Acid Defined diet. Collectively these data suggest that the miR-200/Zeb module could be an important element in the response of the liver to chemical carcinogen exposure.
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 2046.
Abstract 2048: microRNA regulation of tissue factor expression in breast cancer cells
Authors: Zhang Xiao-Xi , Yu Haijun , Lou Jessica R. , Zheng Jie , Popescu Narcis-Ioan , Lupu Florea , Ding Wei-Qun 
Published: February 2011

Abstract
Tissue factor is recognized to be an important regulator of tumor angiogenesis and metastasis, independent of its participation in the blood coagulation pathway. The tissue factor gene is highly expressed only in breast carcinoma cells having high invasive potential, but the mechanisms regulating tissue factor gene expression in breast cancer cells remain unclear. This study examined the hypothesis that microRNA regulation of tissue factor expression is responsible for over-expression of the tissue factor gene in invasive breast cancer cells. Tissue factor was highly expressed in the highly invasive MDA-MB-231 line but was barely detectable in the less invasive MCF-7 line, as assayed by RT-PCR and western blot. A reporter gene assay showed that the tissue factor promoter can be activated in extracts prepared from MCF-7 cells. Forced expression of tissue factor cDNA was achieved in MCF-7 cells, implying that that tissue factor expression is regulated by the 3′-UTR of its transcript. Bioinformatics analysis suggested that microRNA species such as miR-19 (miR-19a and 19b) and miR-106b interact with the 3’-UTR of the tissue factor transcript and may regulate tissue factor protein translation and/or mRNA degradation. microRNA array confirmed that miR-19b is highly expressed in MCF-7 cells, as compared to MDA-MB-231 cells. A reporter gene assay using a TF-3′-UTR-luciferase construct indicated that the tissue factor 3′-UTR negatively regulates tissue factor expression, an effect that was completely reversed by deletion of the miR-19 binding site in the reporter construct. Application of an antisense microRNA for miR-19 enhanced tissue factor expression in MCF-7 cells. This study demonstrates that tissue factor expression in breast cancer cells is regulated by miR-19. The expression pattern of miR-19 in breast cancer tissues and its role in mediating angiogenesis and metastasis merit future investigation.
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 2048.
Abstract 2058: Translational regulation of SPARC by the microRNAs mir29a, b, and c
Authors: Trieu Vuong , Hwang Larn , Lin Xiaoqin , Tamir Rami , Motamed Kouros , Desai Neil 
Published: February 2011

Abstract
Background: SPARC (Secreted Protein Acidic and Rich in Cysteine) is overexpressed in most cancers, including breast, prostate, lung, brain, head-and-neck, and kidney. SPARC overexpression enhances tumor progression, angiogenesis, and metastasis and is generally associated with poor prognosis. In a previous study, SPARC mRNA was detected among the majority of both normal and cancer tissues using RT-PCR, in contrast to immunohistochemistry (IHC) that showed SPARC protein only in tissue remodeling and in cancers. These results suggested a post-transcriptional regulation of SPARC mRNA. We report here microRNA (miRNA) mediated regulation of SPARC mRNA.
Methods: A chimera expression vector with CMV driven Luciferase ORF upstream of SPARC's 3′UTR was constructed and used in an assay to detect miRNA mediated suppression of luciferase translation. The construct was co-transfected into a permissive cell line- HEK293 (embryonic kidney cells) and individual miRNA mimics or inhibitors obtained from Dharmacon (Lafayette, Co, USA). Inhibitors of luciferase ORF were detected by a suppression of the luciferase signal. Deletion analysis on SPARC's 3′UTR was also performed to localize sequence required for translational suppression. Findings using CHO and 293 cells were confirmed using other cell lines including ES-2, SKOV-3, CAOV-3, PA-1, U87-MG, and OVCAR-3.
Results: It was noted during forced expression of SPARC that CHO cells did not support SPARC overexpression, whereas HEK293 could. Screening using the luciferase ORF linked to SPARC's 3′UTR revealed that mir29 a, b and c were able to cause translational inhibition of SPARC mRNA. Deletion mutants of 3′UTR from SPARC restored the luciferase activity, whereas inhibition was retained when region 1-236 nt of SPARC's 3′UTR was maintained suggesting that the mir29 binding sequence is located within this region. The finding was not specific to CHO, and mir29 inhibition of SPARC expression was confirmed among all other cell lines tested (ES-2, SKOV-3, CAOV-3, PA-1, U87-MG and OVCAR-3).
Conclusions: Human mir29a, b and c down-regulated the SPARC translation across a number of cell lines tested. These data suggest that that miRNAs mir29 a, b and c could play an important role in tumor metastasis and progression by control of SPARC expression.
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 2058.