title: An apoptotic pathway of 3'-Ethynylcytidine(ECyd) involving the inhibition of RNA synthesis mediated by RNase L.
abstract: RNase L is an endoribonuclease that requires 2'-5' oligoadenylate to cleave single-stranded RNA. Although the antiviral effects of RNase L are well known because of its viral RNA degradation activity recently but it has been suggested that RNase L is concerned in mitochondrial-caspase dependent apoptotic signaling pathway induced by a number of anticancer agents. Moreover, it has variety of functions including translation and transcription of proteins. In this report, we found that 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl) cytosine (ECyd), which inhibits RNA synthesis through competitive inhibition of RNA polymerase I induced 28S rRNA fragmentation. The cleavage pattern of rRNA induced by ECyd was similar and the cleavage sites were identical to those cleaved by RNase L. Additionaly, apoptosis induced by ECyd was elevated following the protein expression of RNase L in the tumor cells when treated with IFN-alpha2a which was known to induce RNase L expression. To identify the role of RNase L in apoptosis induced by ECyd, we detected the decreased level of RNase L by several folds in the tumor cell lines through a small interfering RNA (siRNA). These results indicated that RNase L might integrate apoptotic signals induced by ECyd and provide the possibility to be a novel clinical target for cancer chemotherapy.
authors.affiliation: Faculty of Pharmaceutical Sciences, Okayama University, Okayama, Japan.
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Naito
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Yokogawa
authors.forename: Hye-Sook
authors.initials: HS
authors.lastname: Kim
authors.forename: Akira
authors.initials: A
authors.lastname: Matsuda
authors.forename: Takuma
authors.initials: T
authors.lastname: Sasaki
authors.forename: Masakazu
authors.initials: M
authors.lastname: Fukushima
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kitade
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Wataya
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D045744:Cell Line, Tumor; D003562:Cytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004722:Endoribonucleases / Q000378:metabolism*; D006801:Humans; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology*; D012313:RNA / Q000096:biosynthesis*; D012318:RNA Polymerase I / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C103084:1-(3-C-ethynylribopentofuranosyl)cytosine; D000970:Antineoplastic Agents; D019384:Nucleic Acid Synthesis Inhibitors; D003562:Cytidine; D012313:RNA; D012318:RNA Polymerase I; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease