Recombinant adenovirus encoding H-ras ribozyme induces apoptosis in laryngeal cancer cells through caspase- and mitochondria-dependent pathways

Chih Hung Wang, Li Jen Tsai, Yeou Ping Tsao, Jer Tsong Hsieh, Wei Wen Chien, Ching Len Liao, Hsing Won Wang, Hsiao Sheng Liu, Show Li Chen

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Previously, we designed a ribozyme that targets the H-ras oncogene at the 12th codon mutation site (Chang et al., 1997). Ribozymes have antisense molecule and site-specific ribonuclease potential. In this study, an adenoviral vector was used to transduce the H-ras ribozyme into laryngeal cancer cells (HEp-2). This served to downregulate the H-ras gene expression in which this ribozyme performed antisense activity due to HEp-2 cells containing wild-type alleles in the 12th H-ras codon. Together, our data demonstrated that the recombinant adenovirus encoding H-ras ribozyme can be broadly regarded as a cytotoxic gene therapy in laryngeal cancer cells regardless of containing wild-type or mutant ras gene. In addition, the mechanism through which the H-ras ribozyme inhibited tumor growth was apoptosis and involved both caspase- and mitochondria-mediated pathways. The activators caspase-8 and -9 as well as the effector caspase-3 in the induction phase of apoptosis and the substrate PARP of caspase-3 in the execution phase were activated 48 h following the H-ras ribozyme treatment. Mitochondrial events characterized by the production of superoxide anion and the release of cytochrome c started at 24 h. Mitochondrial transmembrane potential loss occurred 48 h after the ribozyme treatment. However, Bcl-2 delayed cytochrome c release to the cytosol, but it could not protect the apoptosis effect, suggesting that cytochrome c release from mitochondria may not play a role in H-ras ribozyme-induced apoptosis.

Original languageEnglish
Pages (from-to)805-814
Number of pages10
JournalBiochemical and Biophysical Research Communications
Issue number5
Publication statusPublished - 2002
Externally publishedYes



  • Apoptosis
  • Caspase
  • H-ras
  • Mitochondria

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

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