title: A novel telomerase template antagonist (GRN163) as a potential anticancer agent.
abstract: Telomerase, the enzyme responsible for proliferative immortality, is expressed in essentially all cancer cells, but not in most normal human cells. Thus, specific telomerase inhibition is potentially a universal anticancer therapy with few side effects. We designed N3'-->P5' thio-phosphoramidate (NPS) oligonucleotides as telomerase template antagonists and found that their ability to form stable duplexes with the telomerase RNA subunit was the key factor for antitelomerase activity. In biochemical assays 11-13-mer NPS oligonucleotides demonstrated sequence- and dose-dependent inhibition of telomerase with IC(50) values <1 nM. Optimization of the sequence, length, and bioavailability resulted in the selection of a 13-mer NPS oligonucleotide, GRN163, as a drug development candidate. GRN163 inhibited telomerase in a cell-free assay at 45 +/- 7 pM, and in various tumor cell lines at approximately 1 nM and approximately 0.3-1.0 micro M in the presence and absence of carriers, respectively. GRN163 was competitive with telomeric primer binding, primarily because of hybridization to human telomerase RNA (hTR) component. Tumor cells treated with GRN163 in culture underwent telomere shortening, followed by cellular senescence or apoptosis after a period of time that generally correlated with initial telomere length. In a flank DU145 (prostate cancer) xenograft model, parenterally administered GRN163 caused suppression of tumor growth in the absence of gross toxicity. These data demonstrate that GRN163 has significant potential for additional development as an anticancer agent.
authors.affiliation: Kyowa Hakko Kogyo, Ltd., Pharmaceutical Research Institute, Shizuoka 411-8731, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Asai
authors.forename: Yuko
authors.initials: Y
authors.lastname: Oshima
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Taka-aki
authors.initials: TA
authors.lastname: Uochi
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kusaka
authors.forename: Shiro
authors.initials: S
authors.lastname: Akinaga
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yamashita
authors.forename: Krisztina
authors.initials: K
authors.lastname: Pongracz
authors.forename: Ronald
authors.initials: R
authors.lastname: Pruzan
authors.forename: Ellen
authors.initials: E
authors.lastname: Wunder
authors.forename: Mieczyslaw
authors.initials: M
authors.lastname: Piatyszek
authors.forename: Shihong
authors.initials: S
authors.lastname: Li
authors.forename: Allison C
authors.initials: AC
authors.lastname: Chin
authors.forename: Calvin B
authors.initials: CB
authors.lastname: Harley
authors.forename: Sergei
authors.initials: S
authors.lastname: Gryaznov
mesh_terms: D000577:Amides / Q000378:metabolism / Q000494:pharmacology; D001682:Biological Availability; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D009841:Oligonucleotides / Q000235:genetics / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D010756:Phosphoric Acids / Q000378:metabolism / Q000494:pharmacology; D012313:RNA / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D000577:Amides; D009841:Oligonucleotides; D010756:Phosphoric Acids; D012313:RNA; C011067:phosphoramidic acid; D019098:Telomerase