Telomerase Inhibitors – Oligonucleotide Phosphoramidates as Potential Therapeutic Agents

Gryaznov, Sergei M.; Pongracz, Krisztina; Matray, Tracy J.; Schultz, Ronald G.; Pruzan, Ronald; Aimi, Junko; Chin, Alice; Harley, Calvin B.; Shea-Herbert, Brittney; Shay, Jerry W.; Oshima, Yutaka; Asai, Akira; Yamashita, Yoshihisa

doi:10.1081/ncn-100002314

Cited by 64 publications

(60 citation statements)

References 19 publications

(6 reference statements)

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“…Following this appealing scienti®c rationale, several classes of telomerase inhibitors were prepared and evaluated. Among the compounds tested were small molecules (Naasani et al, 1998(Naasani et al, , 1999Bare et al, 1998;Hisatake et al, 1999), compounds capable of interacting with DNA G-quadruplex structures (Neidle et al, 2000;Hurley et al, 2000), dominant negative hTERTderived proteins (Hahn et al, 1999), antisense RNA (Feng et al, 1995;Yamaguchi et al, 1999), and various types of oligonucleotides, including DNA phosphodiesters (Glukhov et al, 1998), 2-5A tethered phosphodiesters (Kondo et al, 1998), phosphorothioates (Norton et al, 1996;Matthes and Lehmann, 1999;Sharma et al, 1996), phosphoramidates (Gryaznov et al, 2001), 2'-O-Methyl and 2'-O-(Methoxy-ethyl) phosphorothioate chimera (Pitts and Corey, 1998;Elayadi et al, 2001), ribozymes (Wan et al, 1998), and PNA molecules (Norton et al, 1996). The e ects of DNA, PNA and 2'-modi®ed RNA oligonucleotides reportedly were sequence speci®c, unlike the activity of the majority of earlier generation of phosphorothioates oligomers (Matthes and Lehman, 1999).…”

Section: Introductionmentioning

confidence: 99%

Oligonucleotide N3′→P5′ phosphoramidates as efficient telomerase inhibitors

et al. 2002

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Human telomerase is a unique reverse transcriptase that is expressed in multiple cancers, but not in the vast majority of normal cells. The enzyme is responsible for telomere protection and maintenance, and supports the proliferative immortality of cancer cells. Thus, it has been proposed that the speci®c inhibition of telomerase activity in tumors might have signi®cant and bene®cial therapeutic e ects. To this goal we have designed, synthesized, and evaluated several oligonucleotide N3'?P5' phosphoramidates as telomerase inhibitors. These oligonucleotides are complementary to the template region of the RNA domain of telomerase (hTR). The prepared compounds were evaluated in HME50-5E breast epithelial cells, where their e ects on telomerase activity were determined using a cell-based telomerase (TRAP) assay at 24 as well as 72 h after exposure to compounds. The oligo-N3'?P5' phosphoramidate inhibited telomerase activity in cells in the presence of the cellular up-take enhancer (FuGENE6 TM ) in a dose-and sequence-dependent manner, with IC 50 values of approximately 1 nM. Inhibition of telomerase activity by this compound without the lipid carrier was not e cient. However, the isosequential oligonucleotide N3'?P5' thio-phosphoramidate was able to inhibit telomerase activity with or without lipid carriers at nM, or low-mM concentrations, respectively. This inhibition of telomerase activity in HME50-5E cells by the oligonucleotide thio-phosphoramidates was also sequence speci®c. Long-term treatment of the cells with 0.5 mM of FuGENE6 formulated 13-mer thio-phosphoramidates, fully complementary to hTR, resulted in gradual telomere shortening, followed by cellular senescence and apoptosis, as would be predicted for a telomerase inhibitor. The mismatched control compound had no e ect on cell proliferation. The results suggest that the oligonucleotide N3'?P5' phosphoramidates, and particularly thio-phosphoramidates, might be further developed as selective anti-telomerase reagents.

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Section: Introductionmentioning

confidence: 99%

Oligonucleotide N3′→P5′ phosphoramidates as efficient telomerase inhibitors

et al. 2002

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“…30 We found that GRN163 decreased TA in all cell lines and enhanced telomeric shortening in a lymphoma cell line (telomere length, 4.5 kb) after 33 days. Continuous GRN163 exposure of malignant cell lines with short telomeres (1.7-5.4 kb) resulted in the rapid dose-dependent induction of proliferative arrest and cell death, whereas up to 40 days of GRN163 treatment of cells with long telomere lengths did not influence proliferation.…”

Section: Introductionmentioning

confidence: 92%

“…GRN163 is resistant to hydrolysis by cellular nucleases and exhibits high thermodynamic stability. 30 Earlier biochemical assays demonstrated that GRN163 inhibits human telomerase in a sequence-specific manner, with IC 50 values in the sub-nanomolar range and IC 50 values of 0.5 M against solid tumor cell lines in the absence of uptake enhancers. 30 In the absence of exogenous uptake enhancers, 3Ј-fluoresceinlabeled GRN163 oligonucleotide was added to cultured cells.…”

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confidence: 99%

“…38 The GRN163 compound forms a high-affinity, sequence-specific duplex with the complementary RNA strand that is further stabilized through interactions between the oligonucleotide backbone and hTERT, is resistant to hydrolysis by cellular nucleases, and exhibits high thermodynamic stability. 30 The effects of GRN163 were evaluated on the growth of human MM and NHL cell lines, primary MM cells, and tumor xenografts. GRN163 treatment reduced telomerase levels in all cells and induced progressive telomeric shortening in cell lines.…”

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confidence: 99%

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Telomerase inhibition with an oligonucleotide telomerase template antagonist: in vitro and in vivo studies in multiple myeloma and lymphoma

Wang

Chin

et al. 2004

Blood

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The effects of telomerase inhibition with an oligonucleotide N3 3 P5 thiophosphoramidate (GRN163) complementary to the telomerase template region were examined on human multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) cell lines, primary MM cells, and tumor xenografts. GRN163 treatment reduced telomerase levels in all cells and induced more rapid telomeric shortening. Continuous GRN163 treatment for 7 to 14 days resulted in proliferative arrest, morphologic changes, and apoptosis characteristic of cell crisis in tumor cell lines with short (1.7-5.4 kb) but not long (9-11 kb) telomeres. Intratumoral administration of GRN163 also inhibited the growth of MM and NHL xenografts established from cell lines with short telomeres (Hs602 lymphoma, 2.7 kb; CAG myeloma, 2.7 kb) and increased tumor apoptosis. However, GRN163 therapy of NHL xenografts established from cells with long telomeres (11.0 kb) had equivocal effects on tumor growth and did not induce apoptosis during this time frame. Systemic daily intraperitoneal administration of GRN163 in myeloma xenografts with short telomere lengths also decreased tumor telomerase levels and reduced tumor volumes. These data demonstrate that telomerase is important for the replication of mature B-cell neoplasia by stabilizing short telomeres, and they suggest that telomerase inhibition represents a novel therapeutic approach to MM and NHL. IntroductionThe preservation of telomeres, DNA-protein structures located at the ends of eukaryotic chromosomes, is essential to the immortalization process. In most normal somatic cells, telomeric DNA is progressively lost with each cell division until a critically short telomere length is obtained, and telomeres lose the ability to protect linear chromosomal ends. The resultant telomeric dysfunction induces cell "crisis" with chromosomal instability, end-to-end chromosome fusions, activation of DNA checkpoint responses, apoptosis, and cell death. 1 Human telomerase is a complex ribonucleoprotein reverse transcriptase composed of an RNA template (hTR) and a catalytic protein subunit (hTERT), which is responsible for synthesizing d-(TTAGGG) n telomeric repeats at chromosomal ends. Stabilizing telomeric DNA through telomerase up-regulation or activating alternative mechanisms of telomere maintenance is essential if cells are to survive and proliferate indefinitely. 2 Telomerase activity (TA) is not found in most normal somatic cells, which lack hTERT, but it has been detected in high levels in 85% to 90% of human cancers. 1 Although telomerase is not an oncogene, 3 transfecting hTERT into normal epithelial or endothelial cells transformed with the simian virus 40 large T-antigen and the N-ras oncogene allows cells to bypass crisis and ultimately to achieve malignancy, confirming the role of telomerase in cellular immortalization and tumorigenesis. 1 Telomerase inhibition by numerous strategies, including dominant-negative telomerase mutants, 4,5 small-molecular-weight compounds, 6 reversetranscriptase inhibitors, 7 G-quadruplex interactive...

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“…This difference significantly contributes to making cancer cells more sensitive to telomerase inhibitors and may allow for a substantial therapeutic window for telomerase inhibition. One such inhibitor is GRN163L, a lipidated 13-mer oligonucleotide complementary to the RNA template region of human telomerase RNA (hTR) [175,176]. Its mechanism of action is not that of antisensemediated RNase H catalyzed hydrolysis but that it acts as a template antagonist, thus inhibiting telomerase activity.…”

Section: Targeting Senescencementioning

confidence: 99%

Chemotherapeutic Approaches for Targeting Cell Death Pathways

2006

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Learning Objectives After completing this course, the reader will be able to: List the multiple cell death pathways that are activated in response to chemotherapeutic agents. Identify signaling molecules involved and morphological changes that occur in the different types of cell death pathways. Describe mechanisms targeted by novel chemotherapeutic agents. Access and take the CME test online and receive 1 AMA PRA category 1 credit at http://CME.TheOncologist.com For several decades, apoptosis has taken center stage as the principal mechanism of programmed cell death in mammalian tissues. It also has been increasingly noted that conventional chemotherapeutic agents not only elicit apoptosis but other forms of nonapoptotic death such as necrosis, autophagy, mitotic catastrophe, and senescence. This review presents background on the signaling pathways involved in the different cell death outcomes. A re‐examination of what we know about chemotherapy‐induced death is vitally important in light of new understanding of nonapoptotic cell death signaling pathways. If we can precisely activate or inhibit molecules that mediate the diversity of cell death outcomes, perhaps we can succeed in more effective and less toxic chemotherapeutic regimens.

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Telomerase Inhibitors – Oligonucleotide Phosphoramidates as Potential Therapeutic Agents

Cited by 64 publications

References 19 publications

Oligonucleotide N3′→P5′ phosphoramidates as efficient telomerase inhibitors

Oligonucleotide N3′→P5′ phosphoramidates as efficient telomerase inhibitors

Telomerase inhibition with an oligonucleotide telomerase template antagonist: in vitro and in vivo studies in multiple myeloma and lymphoma

Chemotherapeutic Approaches for Targeting Cell Death Pathways

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