Analysis of Telomerase RNA Gene Expression by In Situ Hybridization

Keith, W. Nicol; Sarvesvaran, Joseph; Downey, Martin

doi:10.1385/1-59259-189-2:65

Cited by 4 publications

(2 citation statements)

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“…In situ hybridization analysis of 800 tumor biopsy samples show clearly that hTR levels are up-regulated specifically in cancer cells (35)(36)(37)(38)(39)(40). It is, therefore, critical to begin to define pathways affecting hTR.…”

Section: Discussionmentioning

confidence: 99%

Transcriptional Repression of Telomerase RNA Gene Expression by c-Jun-NH2-Kinase and Sp1/Sp3

Bilsland

Stevenson²,

Atkinson³

et al. 2006

Cancer Research

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Telomerase is essential for immortalization of most human cancer cells. Expression of the core telomerase RNA (hTR) and reverse transcriptase (hTERT) subunits is mainly regulated by transcription. However, hTR transcriptional regulation remains poorly understood. We previously showed that the core hTR promoter is activated by Sp1 and is repressed by Sp3. Here, we show that the mitogen-activated protein kinase kinase kinase 1 (MEKK1)/c-Jun-NH 2 -kinase (JNK) pathway represses hTR expression by a mechanism that involves Sp1 and Sp3. Promoter activity was induced by the JNK inhibitor SP600125 and was repressed by activated MEKK1. Repression by MEKK1 was blocked by SP600125 or enhanced by coexpression of wild-type but not phosphoacceptor mutated JNK. SP600125 treatment also increased levels of endogenous hTR. Mutations in the hTR promoter Sp1/Sp3 binding sites attenuated SP600125-mediated promoter induction, whereas coexpression of MEKK1 with Sp3 enhanced hTR promoter repression. Chromatin immunoprecipitation showed that levels of immunoreactive Sp1 associated with the hTR promoter were low in comparison with Sp3 in control cells but increased after JNK inhibition with a reciprocal decrease in Sp3 levels. No corresponding changes in Sp1/Sp3 protein levels were detected. Thus, JNK represses hTR promoter activity and expression, apparently by enhancing repression

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Section: Discussionmentioning

confidence: 99%

Transcriptional Repression of Telomerase RNA Gene Expression by c-Jun-NH2-Kinase and Sp1/Sp3

Bilsland

Stevenson²,

Atkinson³

et al. 2006

Cancer Research

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“…Selective telomerase expression in cancer cells is mainly the result of aberrant transcription of hTR and hTERT; both transcripts are easily detectable in cancer cells but are either absent or at low levels in normal cells when assayed by appropriate methodologies (8)(9)(10)(11)(12)(13). Interestingly, the cloned hTR and hTERT promoters also show selective activity in cancer cells with the hTR promoter usually stronger than hTERT (14)(15)(16)(17)(18)(19).…”

Section: Introductionmentioning

confidence: 99%

Modulation of Telomerase Promoter Tumor Selectivity in the Context of Oncolytic Adenoviruses

et al. 2007

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The telomerase RNA (hTR) and reverse transcriptase (hTERT) promoters are active in most cancer cells, but not in normal cells, and are useful for transcriptional targeting in gene therapy models. Telomerase-specific conditionally replicating adenoviruses (CRAd) are attractive vectors because they should selectively lyse tumor cells. Here, we compare CRAds, in which either the hTR or hTERT promoter controls expression of the adenovirus E1A gene. In replicationdefective reporter adenoviruses, the hTR promoter was up to 57-fold stronger in cancer cells than normal cells and up to 49-fold stronger than hTERT. In normal cells, hTERT promoter activity was essentially absent. Doses of telomerase-specific CRAds between 1.8 and 28 infectious units per cell efficiently killed cancer cells, but normal cells required higher doses. However, CRAd DNA replication and E1A expression were detected in both cancer and normal cells. Overall, tumor specificity of the CRAds was limited compared with nonreplicating vectors. Surprisingly, both CRAds expressed similar E1A levels and functional behavior, despite known differentials between hTR and hTERT promoter activities, suggesting that the promoters are deregulated. Rapid amplification of cDNA ends analysis of hTR-/hTERT-E1A transcripts ruled out cryptic transcription from the vector backbone. Blocking E1A translation partially restored the hTR-/hTERT-E1A mRNA differential, evidencing feedback regulation by E1A.

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Use of High Throughput Genomic Tools for the Study of Endothelial Cell Biology

Tabibiazar

Quertermous²

2003

Lymphatic Research and Biology

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The endothelium is an active, dynamic and heterogeneous organ. It lines the vessels in every organ system and regulates diverse and important biological functions. Over the past several years researchers have gained enormous insights into endothelial cell function in physiological processes such as coagulation and vascular reactivity, and pathophysiological disease states such as inflammation and atherosclerosis. Despite our expanding knowledge of endothelial cell biology, the molecular mechanisms underlying these functions remain largely unknown. The newly developed high throughput genomic tools and accompanying analytical methods provide powerful approaches for identifying new endothelial cell genes and characterizing their role in health and disease. Here, we review some of the recent genomics and proteomic advances that are providing new methodologies for endothelial cell and vascular biology research.

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Analysis of Telomerase RNA Gene Expression by In Situ Hybridization

Cited by 4 publications

References 1 publication

Transcriptional Repression of Telomerase RNA Gene Expression by c-Jun-NH2-Kinase and Sp1/Sp3

Transcriptional Repression of Telomerase RNA Gene Expression by c-Jun-NH2-Kinase and Sp1/Sp3

Modulation of Telomerase Promoter Tumor Selectivity in the Context of Oncolytic Adenoviruses

Use of High Throughput Genomic Tools for the Study of Endothelial Cell Biology

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