Jian-Ting Wang1, Shu-Sheng Gong. 1. Department of Otorhinolaryngology, Head and Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing 100020, China. tingjianwang@yahoo.com.cn
Abstract
BACKGROUND: The relationship between apoptosis and tumors is a major focus in cancer research. RNA interference (RNAi) technology has emerged as a very potent tool to generate cellular knockdown phenotypes of a desired gene. The aim of this study was to explore the effect of siRNA specific to the protein casein kinase 2α (CK2α) on apoptosis of laryngeal carcinoma cells and to explore possible mechanisms. METHODS: An siRNA expression plasmid specific to CK2α, psiRNA-hH1neo-CK2α, and a non-specific siRNA expression plasmid, psiRNA-hH1neo-cont, were constructed and transfected into Hep-2 cells by a lipofectamine method. The mRNA and protein levels of CK2α in transfected cells were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting analysis. Apoptosis was measured by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double-staining methods. The morphological changes to Hep-2 cells were observed under transmission electron microscopy (TEM). The levels of Bcl-2 and Bax proteins were measured by Western blotting analysis. RESULTS: Levels of CK2α mRNA and protein were significantly decreased in the psiRNA-hH1neo-CK2α group compared to the other groups (P < 0.05). The apoptotic rate of the psiRNA-hH1neo-CK2α transfected group was significantly higher compared to that in the untransfected group and the siRNA-hH1neo-cont transfected group (25.66% ± 0.83%, 3.66% ± 0.43%, and 5.18% ± 0.22%) (P < 0.05). Compared with the untransfected group and the siRNA-hH1neo-cont transfected group, the psiRNA-hH1neo-CK2α transfected group presented with classical ultrastructural features of apoptosis, such as karyopyknosis, chromatic agglutination adjacent to the nuclear membrane, and apoptotic bodies. Compared with the other two groups, the level of Bcl-2 protein in the psiRNA-hH1neo-CK2α transfected group was decreased (0.20 ± 0.09 vs. 0.72 ± 0.16, 0.56 ± 0.11, P < 0.01), while the Bax protein level was increased (0.81 ± 0.17 vs. 0.26 ± 0.12, 0.33 ± 0.17, P < 0.01) and the ratio of Bcl-2 to Bax was decreased (0.25 ± 0.05 vs. 2.76 ± 0.21, 1.70 ± 0.22, P < 0.01). CONCLUSIONS: The siRNA expression plasmid specific to CK2α could suppress CK2α expression and induce the apoptosis of laryngeal carcinoma cells. This is possibly by decreasing the Bcl-2/Bax ratio. CK2α may provide a potential therapeutic target against human laryngeal carcinoma.
BACKGROUND: The relationship between apoptosis and tumors is a major focus in cancer research. RNA interference (RNAi) technology has emerged as a very potent tool to generate cellular knockdown phenotypes of a desired gene. The aim of this study was to explore the effect of siRNA specific to the protein casein kinase 2α (CK2α) on apoptosis of laryngeal carcinoma cells and to explore possible mechanisms. METHODS: An siRNA expression plasmid specific to CK2α, psiRNA-hH1neo-CK2α, and a non-specific siRNA expression plasmid, psiRNA-hH1neo-cont, were constructed and transfected into Hep-2 cells by a lipofectamine method. The mRNA and protein levels of CK2α in transfected cells were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting analysis. Apoptosis was measured by Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) double-staining methods. The morphological changes to Hep-2 cells were observed under transmission electron microscopy (TEM). The levels of Bcl-2 and Bax proteins were measured by Western blotting analysis. RESULTS: Levels of CK2α mRNA and protein were significantly decreased in the psiRNA-hH1neo-CK2α group compared to the other groups (P < 0.05). The apoptotic rate of the psiRNA-hH1neo-CK2α transfected group was significantly higher compared to that in the untransfected group and the siRNA-hH1neo-cont transfected group (25.66% ± 0.83%, 3.66% ± 0.43%, and 5.18% ± 0.22%) (P < 0.05). Compared with the untransfected group and the siRNA-hH1neo-cont transfected group, the psiRNA-hH1neo-CK2α transfected group presented with classical ultrastructural features of apoptosis, such as karyopyknosis, chromatic agglutination adjacent to the nuclear membrane, and apoptotic bodies. Compared with the other two groups, the level of Bcl-2 protein in the psiRNA-hH1neo-CK2α transfected group was decreased (0.20 ± 0.09 vs. 0.72 ± 0.16, 0.56 ± 0.11, P < 0.01), while the Bax protein level was increased (0.81 ± 0.17 vs. 0.26 ± 0.12, 0.33 ± 0.17, P < 0.01) and the ratio of Bcl-2 to Bax was decreased (0.25 ± 0.05 vs. 2.76 ± 0.21, 1.70 ± 0.22, P < 0.01). CONCLUSIONS: The siRNA expression plasmid specific to CK2α could suppress CK2α expression and induce the apoptosis of laryngeal carcinoma cells. This is possibly by decreasing the Bcl-2/Bax ratio. CK2α may provide a potential therapeutic target against humanlaryngeal carcinoma.