title: Long (27-nucleotides) small inhibitory RNAs targeting E6 protein eradicate effectively the cervical cancer cells harboring human papilloma virus.
abstract: OBJECTIVE
  This study was to identify small inhibitory RNAs (siRNAs) that are effective in inhibiting growth of cervical cancer cell lines harboring human papilloma virus (HPV) and to examine how siRNAs interact with interferon beta (IFN-β) and thimerosal.
  
  
  METHODS
  The HPV18-positive HeLa and C-4I cell lines were used. Four types of siRNAs were designed according to their target (both E6 and E7 vs. E6 only) and sizes (21- vs. 27-nucleotides); Ex-18E6/21, Ex-18E6/27, Sp-18E6/21, and Sp-18E6/27. Each siRNA-transfected cells were cultured with or without IFN-b and thimerosal and their viability was measured.
  
  
  RESULTS
  The viabilities of HPV18-positive tumor cells were reduced by 21- and 27-nucleotide siRNAs in proportion to the siRNA concentrations. Of the two types of siRNAs, the 27-nucleotide siRNA constructs showed greater inhibitory efficacy. Sp-18E6 siRNAs, which selectively downregulates E6 protein only, were more effective than the E6- and E7-targeting Ex-18E6 siRNAs. siRNAs and IFN-β showed the synergistic effect to inhibit HeLa cell survival and the effect was proportional to both siRNA and IFN-β concentrations. Thimerosal in the presence of siRNA exerted a dose-dependent inhibition of C-4I cell survival. Finally, co-treatment with siRNA, IFN-β, and thimerosal induced the most profound decrease in the viability of both cell lines.
  
  
  CONCLUSIONS
  Long (27-nucleotides) siRNAs targeting E6-E7 mRNAs effectively reduce the viability of HPV18-positive cervical cancer cells and show the synergistic effect in combination with IFN-b and thimerosal. It is necessary to find the rational design of siRNAs and effective co-factors to eradicate particular cervical cancer.
authors.affiliation: Department of Obstetrics and Gynecology, Liz & Marian Hospital, Cheonan, Korea.
authors.forename: Jun Sik
authors.initials: JS
authors.lastname: Cho
authors.affiliation: Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Shin-Wha
authors.initials: SW
authors.lastname: Lee
authors.affiliation: Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Yong-Man
authors.initials: YM
authors.lastname: Kim
authors.affiliation: Genolution Inc., Seoul, Korea.
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Dae-Yeon
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Department of Obstetrics and Gynecology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.
authors.forename: Young-Tak
authors.initials: YT
authors.lastname: Kim
keywords: E6 protein; E7 protein; Human papilloma virus type 18; Small inhibitory RNA; Uterine cervical neoplasms