Publications by authors named "Rahima Patel"

19 Publications

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RUNX1 marks a luminal castration-resistant lineage established at the onset of prostate development.

Elife 2020 10 7;9. Epub 2020 Oct 7.

Cancer Research United Kingdom, Stem Cell Biology Group, Cancer Research United Kingdom Manchester Institute, The University of Manchester, Alderley Park, Alderley Edge, Macclesfield, United Kingdom.

The characterization of prostate epithelial hierarchy and lineage heterogeneity is critical to understand its regenerative properties and malignancies. Here, we report that the transcription factor RUNX1 marks a specific subpopulation of proximal luminal cells (PLCs), enriched in the periurethral region of the developing and adult mouse prostate, and distinct from the previously identified NKX3.1 luminal castration-resistant cells. Using scRNA-seq profiling and genetic lineage tracing, we show that RUNX1 PLCs are unaffected by androgen deprivation, and do not contribute to the regeneration of the distal luminal compartments. Furthermore, we demonstrate that a transcriptionally similar RUNX1 population emerges at the onset of embryonic prostate specification to populate the proximal region of the ducts. Collectively, our results reveal that RUNX1 PLCs is an intrinsic castration-resistant and self-sustained lineage that emerges early during prostate development and provide new insights into the lineage relationships of the prostate epithelium.
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http://dx.doi.org/10.7554/eLife.60225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7644213PMC
October 2020

RUNX1 Dosage in Development and Cancer.

Mol Cells 2020 Feb;43(2):126-138

Cancer Research UK Stem Cell Biology Group, Cancer Research UK Manchester Institute, The University of Manchester, Macclesfield, SK10 4TG, UK.

The transcription factor RUNX1 first came to prominence due to its involvement in the t(8;21) translocation in acute myeloid leukemia (AML). Since this discovery, RUNX1 has been shown to play important roles not only in leukemia but also in the ontogeny of the normal hematopoietic system. Although it is currently still challenging to fully assess the different parameters regulating RUNX1 dosage, it has become clear that the dose of RUNX1 can greatly affect both leukemia and normal hematopoietic development. It is also becoming evident that varying levels of RUNX1 expression can be used as markers of tumor progression not only in the hematopoietic system, but also in non-hematopoietic cancers. Here, we provide an overview of the current knowledge of the effects of RUNX1 dosage in normal development of both hematopoietic and epithelial tissues and their associated cancers.
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http://dx.doi.org/10.14348/molcells.2019.0301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7057845PMC
February 2020

HDAC1 and HDAC2 Modulate TGF-β Signaling during Endothelial-to-Hematopoietic Transition.

Stem Cell Reports 2018 04;10(4):1369-1383

CRUK Stem Cell Biology Group, CRUK Manchester Institute, 555 Wilmslow Road, Manchester M20 4GJ, UK. Electronic address:

The first hematopoietic stem and progenitor cells are generated during development from hemogenic endothelium (HE) through trans-differentiation. The molecular mechanisms underlying this endothelial-to-hematopoietic transition (EHT) remain poorly understood. Here, we explored the role of the epigenetic regulators HDAC1 and HDAC2 in the emergence of these first blood cells in vitro and in vivo. Loss of either of these epigenetic silencers through conditional genetic deletion reduced hematopoietic transition from HE, while combined deletion was incompatible with blood generation. We investigated the molecular basis of HDAC1 and HDAC2 requirement and identified TGF-β signaling as one of the pathways controlled by HDAC1 and HDAC2. Accordingly, we experimentally demonstrated that activation of this pathway in HE cells reinforces hematopoietic development. Altogether, our results establish that HDAC1 and HDAC2 modulate TGF-β signaling and suggest that stimulation of this pathway in HE cells would be beneficial for production of hematopoietic cells for regenerative therapies.
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http://dx.doi.org/10.1016/j.stemcr.2018.03.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998800PMC
April 2018

Regulation of RUNX1 dosage is crucial for efficient blood formation from hemogenic endothelium.

Development 2018 03 12;145(5). Epub 2018 Mar 12.

Stem Cell Biology Group, Cancer Research UK Manchester Institute, The University of Manchester, Wilmslow Road, Manchester M20 4BX, UK

During ontogeny, hematopoietic stem and progenitor cells arise from hemogenic endothelium through an endothelial-to-hematopoietic transition that is strictly dependent on the transcription factor RUNX1. Although it is well established that RUNX1 is essential for the onset of hematopoiesis, little is known about the role of RUNX1 dosage specifically in hemogenic endothelium and during the endothelial-to-hematopoietic transition. Here, we used the mouse embryonic stem cell differentiation system to determine if and how RUNX1 dosage affects hemogenic endothelium differentiation. The use of inducible expression combined with alterations in the expression of the RUNX1 co-factor CBFβ allowed us to evaluate a wide range of RUNX1 levels. We demonstrate that low RUNX1 levels are sufficient and necessary to initiate an effective endothelial-to-hematopoietic transition. Subsequently, RUNX1 is also required to complete the endothelial-to-hematopoietic transition and to generate functional hematopoietic precursors. In contrast, elevated levels of RUNX1 are able to drive an accelerated endothelial-to-hematopoietic transition, but the resulting cells are unable to generate mature hematopoietic cells. Together, our results suggest that RUNX1 dosage plays a pivotal role in hemogenic endothelium maturation and the establishment of the hematopoietic system.
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http://dx.doi.org/10.1242/dev.149419DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5868988PMC
March 2018

A novel prospective isolation of murine fetal liver progenitors to study in utero hematopoietic defects.

PLoS Genet 2018 01 4;14(1):e1007127. Epub 2018 Jan 4.

Cancer Research UK Stem Cell Biology Group, Cancer Research UK Manchester Institute, Manchester Cancer Research Centre, The University of Manchester, Manchester, United Kingdom.

In recent years, highly detailed characterization of adult bone marrow (BM) myeloid progenitors has been achieved and, as a result, the impact of somatic defects on different hematopoietic lineage fate decisions can be precisely determined. Fetal liver (FL) hematopoietic progenitor cells (HPCs) are poorly characterized in comparison, potentially hindering the study of the impact of genetic alterations on midgestation hematopoiesis. Numerous disorders, for example infant acute leukemias, have in utero origins and their study would therefore benefit from the ability to isolate highly purified progenitor subsets. We previously demonstrated that a Runx1 distal promoter (P1)-GFP::proximal promoter (P2)-hCD4 dual-reporter mouse (Mus musculus) model can be used to identify adult BM progenitor subsets with distinct lineage preferences. In this study, we undertook the characterization of the expression of Runx1-P1-GFP and P2-hCD4 in FL. Expression of P2-hCD4 in the FL immunophenotypic Megakaryocyte-Erythroid Progenitor (MEP) and Common Myeloid Progenitor (CMP) compartments corresponded to increased granulocytic/monocytic/megakaryocytic and decreased erythroid specification. Moreover, Runx1-P2-hCD4 expression correlated with several endogenous cell surface markers' expression, including CD31 and CD45, providing a new strategy for prospective identification of highly purified fetal myeloid progenitors in transgenic mouse models. We utilized this methodology to compare the impact of the deletion of either total RUNX1 or RUNX1C alone and to determine the fetal HPCs lineages most substantially affected. This new prospective identification of FL progenitors therefore raises the prospect of identifying the underlying gene networks responsible with greater precision than previously possible.
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http://dx.doi.org/10.1371/journal.pgen.1007127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5754050PMC
January 2018

Primitive erythrocytes are generated from hemogenic endothelial cells.

Sci Rep 2017 07 25;7(1):6401. Epub 2017 Jul 25.

Cancer Research UK Stem Cell Biology Group, Cancer Research UK Manchester Institute, The University of Manchester, Wilmslow road, Manchester, M20 4BX, UK.

Primitive erythroblasts are the first blood cells generated during embryonic hematopoiesis. Tracking their emergence both in vivo and in vitro has remained challenging due to the lack of specific cell surface markers. To selectively investigate primitive erythropoiesis, we have engineered a new transgenic embryonic stem (ES) cell line, where eGFP expression is driven by the regulatory sequences of the embryonic βH1 hemoglobin gene expressed specifically in primitive erythroid cells. Using this ES cell line, we observed that the first primitive erythroblasts are detected in vitro around day 1.5 of blast colony differentiation, within the cell population positive for the early hematopoietic progenitor marker CD41. Moreover, we establish that these eGFP cells emerge from a hemogenic endothelial cell population similarly to their definitive hematopoietic counterparts. We further generated a corresponding βH1-eGFP transgenic mouse model and demonstrated the presence of a primitive erythroid primed hemogenic endothelial cell population in the developing embryo. Taken together, our findings demonstrate that both in vivo and in vitro primitive erythrocytes are generated from hemogenic endothelial cells.
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http://dx.doi.org/10.1038/s41598-017-06627-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5526883PMC
July 2017

Identification of novel regulators of developmental hematopoiesis using Endoglin regulatory elements as molecular probes.

Blood 2016 10 23;128(15):1928-1939. Epub 2016 Aug 23.

Lowy Cancer Research Centre and the Prince of Wales Clinical School, University of New South Wales Australia, Sydney, Australia; Department of Haematology, The Prince of Wales Hospital, Sydney, Australia.

Enhancers are the primary determinants of cell identity, and specific promoter/enhancer combinations of Endoglin (ENG) have been shown to target blood and endothelium in the embryo. Here, we generated a series of embryonic stem cell lines, each targeted with reporter constructs driven by specific promoter/enhancer combinations of ENG, to evaluate their discriminative potential and value as molecular probes of the corresponding transcriptome. The Eng promoter (P) in combination with the -8/+7/+9-kb enhancers, targeted cells in FLK1 mesoderm that were enriched for blast colony forming potential, whereas the P/-8-kb enhancer targeted TIE2+/c-KIT+/CD41- endothelial cells that were enriched for hematopoietic potential. These fractions were isolated using reporter expression and their transcriptomes profiled by RNA-seq. There was high concordance between our signatures and those from embryos with defects at corresponding stages of hematopoiesis. Of the 6 genes that were upregulated in both hemogenic mesoderm and hemogenic endothelial fractions targeted by the reporters, LRP2, a multiligand receptor, was the only gene that had not previously been associated with hematopoiesis. We show that LRP2 is indeed involved in definitive hematopoiesis and by doing so validate the use of reporter gene-coupled enhancers as probes to gain insights into transcriptional changes that facilitate cell fate transitions.
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http://dx.doi.org/10.1182/blood-2016-02-697870DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5064716PMC
October 2016

New insights into the regulation by RUNX1 and GFI1(s) proteins of the endothelial to hematopoietic transition generating primordial hematopoietic cells.

Cell Cycle 2016 Aug 11;15(16):2108-2114. Epub 2016 Jul 11.

a CRUK Stem Cell Biology, Cancer Research UK Manchester Institute , Manchester , UK.

The first hematopoietic cells are generated very early in ontogeny to support the growth of the embryo and to provide the foundation to the adult hematopoietic system. There is a considerable therapeutic interest in understanding how these first blood cells are generated in order to try to reproduce this process in vitro. This would allow generating blood products, or hematopoietic cell populations from embryonic stem (ES) cells, induced pluripotent stem cells or through directed reprogramming. Recent studies have clearly established that the first hematopoietic cells originate from a hemogenic endothelium (HE) through an endothelial to hematopoietic transition (EHT). The molecular mechanisms underlining this transition remain largely unknown with the exception that the transcription factor RUNX1 is critical for this process. In this Extra Views report, we discuss our recent studies demonstrating that the transcriptional repressors GFI1 and GFI1B have a critical role in the EHT. We established that these RUNX1 transcriptional targets are actively implicated in the downregulation of the endothelial program and the loss of endothelial identity during the formation of the first blood cells. In addition, our results suggest that GFI1 expression provides an ideal novel marker to identify, isolate and study the HE cell population.
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http://dx.doi.org/10.1080/15384101.2016.1203491DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4993433PMC
August 2016

The Hemogenic Competence of Endothelial Progenitors Is Restricted by Runx1 Silencing during Embryonic Development.

Cell Rep 2016 06 26;15(10):2185-2199. Epub 2016 May 26.

Cancer Research UK Stem Cell Hematopoiesis Group, Cancer Research UK Manchester Institute, The University of Manchester, Manchester M20 4BX, UK. Electronic address:

It is now well-established that hematopoietic stem cells (HSCs) and progenitor cells originate from a specialized subset of endothelium, termed hemogenic endothelium (HE), via an endothelial-to-hematopoietic transition. However, the molecular mechanisms determining which endothelial progenitors possess this hemogenic potential are currently unknown. Here, we investigated the changes in hemogenic potential in endothelial progenitors at the early stages of embryonic development. Using an ETV2::GFP reporter mouse to isolate emerging endothelial progenitors, we observed a dramatic decrease in hemogenic potential between embryonic day (E)7.5 and E8.5. At the molecular level, Runx1 is expressed at much lower levels in E8.5 intra-embryonic progenitors, while Bmi1 expression is increased. Remarkably, the ectopic expression of Runx1 in these progenitors fully restores their hemogenic potential, as does the suppression of BMI1 function. Altogether, our data demonstrate that hemogenic competency in recently specified endothelial progenitors is restrained through the active silencing of Runx1 expression.
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http://dx.doi.org/10.1016/j.celrep.2016.05.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4906370PMC
June 2016

Dynamic Gene Regulatory Networks Drive Hematopoietic Specification and Differentiation.

Dev Cell 2016 Mar 25;36(5):572-87. Epub 2016 Feb 25.

Institute of Cancer end Genomic Sciences, College of Medicine and Dentistry, University of Birmingham, Birmingham B152TT, UK. Electronic address:

Metazoan development involves the successive activation and silencing of specific gene expression programs and is driven by tissue-specific transcription factors programming the chromatin landscape. To understand how this process executes an entire developmental pathway, we generated global gene expression, chromatin accessibility, histone modification, and transcription factor binding data from purified embryonic stem cell-derived cells representing six sequential stages of hematopoietic specification and differentiation. Our data reveal the nature of regulatory elements driving differential gene expression and inform how transcription factor binding impacts on promoter activity. We present a dynamic core regulatory network model for hematopoietic specification and demonstrate its utility for the design of reprogramming experiments. Functional studies motivated by our genome-wide data uncovered a stage-specific role for TEAD/YAP factors in mammalian hematopoietic specification. Our study presents a powerful resource for studying hematopoiesis and demonstrates how such data advance our understanding of mammalian development.
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http://dx.doi.org/10.1016/j.devcel.2016.01.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780867PMC
March 2016

GFI1 proteins orchestrate the emergence of haematopoietic stem cells through recruitment of LSD1.

Nat Cell Biol 2016 Jan 30;18(1):21-32. Epub 2015 Nov 30.

CRUK Stem Cell Biology Group, Cancer Research UK Manchester Institute, The University of Manchester, Wilmslow Road, Manchester M20 4BX, UK.

In vertebrates, the first haematopoietic stem cells (HSCs) with multi-lineage and long-term repopulating potential arise in the AGM (aorta-gonad-mesonephros) region. These HSCs are generated from a rare and transient subset of endothelial cells, called haemogenic endothelium (HE), through an endothelial-to-haematopoietic transition (EHT). Here, we establish the absolute requirement of the transcriptional repressors GFI1 and GFI1B (growth factor independence 1 and 1B) in this unique trans-differentiation process. We first demonstrate that Gfi1 expression specifically defines the rare population of HE that generates emerging HSCs. We further establish that in the absence of GFI1 proteins, HSCs and haematopoietic progenitor cells are not produced in the AGM, revealing the critical requirement for GFI1 proteins in intra-embryonic EHT. Finally, we demonstrate that GFI1 proteins recruit the chromatin-modifying protein LSD1, a member of the CoREST repressive complex, to epigenetically silence the endothelial program in HE and allow the emergence of blood cells.
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http://dx.doi.org/10.1038/ncb3276DOI Listing
January 2016

RUNX1 positively regulates a cell adhesion and migration program in murine hemogenic endothelium prior to blood emergence.

Blood 2014 Sep 31;124(11):e11-20. Epub 2014 Jul 31.

Cancer Research UK Stem Cell Biology Group, and.

During ontogeny, the transcription factor RUNX1 governs the emergence of definitive hematopoietic cells from specialized endothelial cells called hemogenic endothelium (HE). The ultimate consequence of this endothelial-to-hematopoietic transition is the concomitant activation of the hematopoietic program and downregulation of the endothelial program. However, due to the rare and transient nature of the HE, little is known about the initial role of RUNX1 within this population. We, therefore, developed and implemented a highly sensitive DNA adenine methyltransferase identification-based methodology, including a novel data analysis pipeline, to map early RUNX1 transcriptional targets in HE cells. This novel transcription factor binding site identification protocol should be widely applicable to other low abundance cell types and factors. Integration of the RUNX1 binding profile with gene expression data revealed an unexpected early role for RUNX1 as a positive regulator of cell adhesion- and migration-associated genes within the HE. This suggests that RUNX1 orchestrates HE cell positioning and integration prior to the release of hematopoietic cells. Overall, our genome-wide analysis of the RUNX1 binding and transcriptional profile in the HE provides a novel comprehensive resource of target genes that will facilitate the precise dissection of the role of RUNX1 in early blood development.
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http://dx.doi.org/10.1182/blood-2014-04-572958DOI Listing
September 2014

GFI1 and GFI1B control the loss of endothelial identity of hemogenic endothelium during hematopoietic commitment.

Blood 2012 Jul 5;120(2):314-22. Epub 2012 Jun 5.

Cancer Research UK Stem Cell Biology Group, Paterson Institute for Cancer Research, University of Manchester, Manchester, United Kingdom.

Recent studies have established that during embryonic development, hematopoietic progenitors and stem cells are generated from hemogenic endothelium precursors through a process termed endothelial to hematopoietic transition (EHT). The transcription factor RUNX1 is essential for this process, but its main downstream effectors remain largely unknown. Here, we report the identification of Gfi1 and Gfi1b as direct targets of RUNX1 and critical regulators of EHT. GFI1 and GFI1B are able to trigger, in the absence of RUNX1, the down-regulation of endothelial markers and the formation of round cells, a morphologic change characteristic of EHT. Conversely, blood progenitors in Gfi1- and Gfi1b-deficient embryos maintain the expression of endothelial genes. Moreover, those cells are not released from the yolk sac and disseminated into embryonic tissues. Taken together, our findings demonstrate a critical and specific role of the GFI1 transcription factors in the first steps of the process leading to the generation of hematopoietic progenitors from hemogenic endothelium.
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http://dx.doi.org/10.1182/blood-2011-10-386094DOI Listing
July 2012

Can hsp90alpha-targeted siRNA combined with TMZ be a future therapy for glioma?

Cancer Invest 2010 Jul;28(6):608-14

Brain Tumour North West, Faculty of Science and Technology, University of Central Lancashire, Preston, United Kingdom.

Hsp90alpha's vital role in cell cycle progression and apoptosis together with its presence in gliomas and absence in normal tissue, make it a credible target for cancer therapy. Three sets of dsRNA oligos designed to align different regions of the hsp90alpha sequence were used to downregulate hsp90alpha. SiRNA 1, 2, and 3 resulted in significant levels of silencing of hsp90alpha after 48 hr treatment (p < .0001). Concurrent treatment of the glioma cell line U87-MG with siRNA 1 and temozolomide (TMZ) resulted in a 13-fold reduction in the dose of TMZ required to achieve a similar effect if TMZ was used alone.
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http://dx.doi.org/10.3109/07357901003630967DOI Listing
July 2010

Telomerase downregulation in cancer brain stem cell.

Mol Cell Biochem 2009 Nov 9;331(1-2):153-9. Epub 2009 May 9.

Brain Tumour North West, Faculty of Science and Technology, University of Central Lancashire, Preston, UK.

Cancer stem cells (CSCs) are a minute sub-population of self-renewing, immortal cells, which can be responsible for chemoresistance observed in the treatment of cancer. CSCs are similar to cancer cells requiring telomerase activity or alternative mechanisms for their proliferation and regeneration. This study explored the correlation between CD133 (stem cell marker) and telomerase expression using CD133+ cells isolated from the glioma GOS-3 cell line with magnetic affinity cell sorting (MACS). GOS-3 CD133+ showed a transcription downregulation of hTERT ( approximately 100-fold decrease) compared with CD133- cells. In order to further substantiate the novel finding, serum deprivation was adopted to enrich CD133 expression in GOS-3 cells. A pronounced upregulation of cd133 and downregulation of telomerase expression were produced as a consequence of decreasing serum supplement levels in GOS-3 cells. These findings showed for the first time that telomerase is downregulated in brain cancer stem cells compared to cancer cells.
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http://dx.doi.org/10.1007/s11010-009-0153-yDOI Listing
November 2009

Silencing DNA methyltransferase (DNMT) enhances glioma chemosensitivity.

Oligonucleotides 2008 Dec;18(4):365-74

Brain Tumour North West, Faculty of Science, University of Central Lancashire, Preston, UK.

Previously, we demonstrated that demethylation with 5-Aza-2'-deoxycytidine (5azadC) resulted in reduced levels of telomerase that led to telomere shortening, enhanced MGMT expression and enhanced chemosensitivity. Although the results were encouraging, the fact that 5azadC is highly toxic and nonspecific, thus is not favored as a therapeutic molecule. The aim of this research is to downregulate the DNA methyltransferase (DNMT1) gene using three sets of double-stranded RNA oligos designed to align different regions of DNMT1 sequence. Results showed the small-interfering RNA (siRNA) 1 and 3 demonstrated significant levels of silencing DNMT1 and hTERT transcription after 24-hour treatment (p = 0.01) and approximately 90% and 70% transcriptional downregulation of DNMT1 and hTERT, respectively after 48 hours. However, siRNA 2 downregulated DNMT1, hTERT, and MGMT in GOS-3 and U87-MG cells that was attributed to sequence homology between oligo 2 and MGMT complementary DNA. The siRNA-treated glioma cell lines GOS-3 and U87-MG were subjected to two chemotherapeutic agents; taxol and Temozolomide (TMZ). Results suggest that either a combination of siRNA 1 or 3 followed by taxol (2-6 muM) after 48 hours or a combination of siRNA 1 or 3 followed by TMZ (600-1000 microM) after 24 hours would be novel and effective glioma therapies.
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http://dx.doi.org/10.1089/oli.2008.0128DOI Listing
December 2008

The sensitization of glioma cells to cisplatin and tamoxifen by the use of catechin.

Mol Biol Rep 2009 May 26;36(5):1181-6. Epub 2008 Jun 26.

Brain Tumour North West, Faculty of Science, University of Central Lancashire, Preston, UK.

Telomerase expression strongly correlates with the grade of malignancy in glioma with inhibition illustrating a definite increase in chemosensitivity. This study was designed to investigate the effects of a green tea derivative, epigallocatechin-3-gallate (EGCG); together with either cisplatin or tamoxifen in glioma, and to investigate whether these effects are mediated through telomerase suppression. EGCG showed a significant cytotoxic effect on 1321N1 cells after 24 h and on U87-MG cells after 72 h (P < 0.001) without significantly affecting the normal astrocytes. Treatment with EGCG inhibited telomerase expression significantly (P < 0.01) and enhanced the effect of cisplatin and tamoxifen in both 1321N1 (P < 0.01) and U87-MG (P < 0.001) cells. EGCG, as a natural product has enormous potential to be an anti-cancer agent capable of enhancing tumour cell sensitivity to therapy.
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http://dx.doi.org/10.1007/s11033-008-9295-3DOI Listing
May 2009

Epigenetic silencing of telomerase and a non-alkylating agent as a novel therapeutic approach for glioma.

Brain Res 2008 Jan 26;1188:173-81. Epub 2007 Oct 26.

Brain Tumour North West, Faculty of Science, University of Central Lancashire, Preston, UK.

5-Aza-2'-deoxycytidine (5azadC) inhibits DNA methyltransferase and subsequently induces the expression of genes silenced by methylation. While treatment with 5azadC downregulated hTERT and upregulated MGMT expression in two glioma cell lines, there was no change in the expression of these two genes in the normal cell line. However, cell viability was reduced as a result of 5azadC treatment in all three cell lines. 5azadC treatment reduced telomerase expression and activity and subsequently enhanced chemosensitivity towards cisplatin, taxol and tamoxifen but not with the alkylating agents temozolomide (TMZ), carmustine and chlorambucil. To further evaluate the effect of these findings, the level of hTERT and MGMT expression was measured in a recurrent anaplastic ependymoma, seven glioblastoma and two normal brain tissues. While four of eight gliomas and one of the normal tissues expressed MGMT, hTERT was expressed in all gliomas but not in the normal brain tissue. Results of this study suggest that taxol together with 5azadC may be a good therapeutic combination for glioma. In addition, the work on cell lines can be repeated on tissues utilizing hTERT as the therapeutic target for demethylation using 5azadC in glioma.
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http://dx.doi.org/10.1016/j.brainres.2007.10.043DOI Listing
January 2008

Telomerase subunits expression variation between biopsy samples and cell lines derived from malignant glioma.

Brain Res 2007 Feb 2;1134(1):45-52. Epub 2007 Jan 2.

Department of Biological Sciences, University of Central Lancashire, and Neurosurgery Department, Royal Preston Hospital, UK.

Although scientific advances have recognised the prognostic power of telomerase activity in different cancers, as yet there has been no investigation regarding the expression variation of telomerase subunits in glioma tissues and cell lines. In this study, a recurrent anaplastic ependymoma and seven glioblastoma biopsy samples, four cell lines and four controls including two normal brain tissues were analysed for telomerase subunit expression profiles together with telomerase activity. Since telomerase activity is linked to tumourgenesis, the genes were analysed with respect to their expression variation. TEP1 was expressed in all glioma cell lines and 70% of glioblastoma tissues, in addition to the control brain tissues. Tankyrase was expressed in 85% of the glioblastoma tissues and was down-regulated in the recurrent anaplastic ependymoma tissue control cell lines. However, it was expressed in the control tissues. Dyskerin was expressed in all cell lines and tissues apart from U87-MG and NHA cells and the recurrent anaplastic ependymoma tissue. As expected, PARP1 and GAPDH showed constitutive expression throughout all cell lines and tissues since both are known to be housekeeping genes. hTERT was expressed in all glioma cell lines and tissues but was absent in the control cells and tissues. Telomerase activity was absent in IPDDC-A2 cells and 57% of the glioblastoma tissues. These results suggest that hTERT expression and not telomerase activity possibly represents a simple and reliable biological diagnostic tool.
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http://dx.doi.org/10.1016/j.brainres.2006.11.093DOI Listing
February 2007