BACKGROUND: T he second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) was recently identified as a protein that is released from mitochondria in resp...BACKGROUND: T he second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) was recently identified as a protein that is released from mitochondria in response to apoptotic stimuli and promotes apoptosis by antagonizing inhibitor of apoptosis proteins. Furthermore, Smac/DIABLO plays an important regulatory role in the sensitization of cancer cells to both immune- and drug-induced apoptosis. However, little is known about the clinical significance of Smac/DIABLO in various cancers including hepatocellular carcinoma (HCC). This study was undertaken to investigate the expression of Smac and Survivin and their relationship with the apoptosis in primary HCC. METHODS: The expression of Smac and Survivin proteins was evaluated by immunohistochemistry. The mRNA expression of Smac and Survivin was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) in HCC tissues of 50 patients, para-carcinoma tissues of 20 patients, and normal liver tissues of 15 patients. RESULTS: Smac mRNA was detected by RT-PCR in HCC tissues of 21 (42.0%) of the 50 patients, para-carcinoma tissues of 19 (95.0%) of the 20 patients, and normal liver tissues of 15 (100%) of the 15 patients. Survivin mRNA was found in HCC tissues of 46 of the 50 patients, para- carcinoma tissues of 2 of the 20 patients, and normal liver tissues of 0 of 15 patients. Immunohistochemistry revealed Smac protein in HCC tissues of 20 patients (40.0%), in para-carcinoma tissues of 18 patients (90.0%), and normal liver tissues of 15 patients (100.0%). The expression of Smac was significantly different in HCC tissues and non- HCC tissues. Survivin protein was found in HCC tissuesin 45 patients, para-carcinoma tissues in 2 patients, and normal liver tissues in none of the patients. The expression of Survivin was significantly different in HCC tissues and non-HCC tissues. CONCLUSION: Smac inhibits apoptosis of HCC cells by suppression of Survivin, and the two genes probably form an important link in the展开更多
The second mitochondria-derived activator of caspases (Smac) is a novelproapoptotic gene, which plays an important role in the apoptosis-inducing effects of irradiation ontumor cells. The purpose of this study was to ...The second mitochondria-derived activator of caspases (Smac) is a novelproapoptotic gene, which plays an important role in the apoptosis-inducing effects of irradiation ontumor cells. The purpose of this study was to investigate the effects of extrinsic Smac genetransfer and its over-expression in radiotherapeutic sensitivities of cervical cancer cells. Afterthe Smac gene was transferred into the cervical cancer cell line HeLa, subcloned cells were obtainedby persistent G418 selection. Cellular Smac gene expression was detected by RT-PCR and Westernblot, while in vitro cell viabilities were detected by trypan blue staining assay. After treatmentwith X-ray irradiation, cellular radiotherapeutic sensitivities were investigated by tetrazoliumbromide colorimetry. Cellular apoptosis and its rate were determined by electronic microscopy,annexin V-FITC and propidium iodide staining flow cytometry. The expression and activities ofcellular caspase-3 were assayed by Western blot and colorimetry. Smac mRNA and protein levels inHeLa/Smac cells and the selected subclone cell line of cervical cancer were significantly higherthan those of HeLa (P <0. 01). There was no significant difference in cellular viabilities betweenthem (P > 0. 05 ) . However, after irradiation with 8 Gy X-ray, growth activities of HeLa/ Smac werereduced by 22.42% (P < 0. 01). When compared with those of HeLa, partial HeLa/Smac cells presentedcharacteristic morphological changes of apoptosis under electronic microscope, with higher apoptosisrates (16. 4% vs. 6. 2% , P < 0. 01 ) ; the caspase-3 expression levels in HeLa/Smac cells wereimproved significantly (P <0. 01) , while its activities were increased by 3. 42 times (P <0. 01).Stable transfer of the extrinsic Smac gene and its over-expression in cervical cancer cell linecould significantly enhance the expression and activities of cellular caspase-3 and ameliorateapoptosis-inducing effects of irradiation on cancer cells, which was a novel strategy to improveradiotherapeutic effects on cervical cancer.展开更多
文摘BACKGROUND: T he second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (Smac/DIABLO) was recently identified as a protein that is released from mitochondria in response to apoptotic stimuli and promotes apoptosis by antagonizing inhibitor of apoptosis proteins. Furthermore, Smac/DIABLO plays an important regulatory role in the sensitization of cancer cells to both immune- and drug-induced apoptosis. However, little is known about the clinical significance of Smac/DIABLO in various cancers including hepatocellular carcinoma (HCC). This study was undertaken to investigate the expression of Smac and Survivin and their relationship with the apoptosis in primary HCC. METHODS: The expression of Smac and Survivin proteins was evaluated by immunohistochemistry. The mRNA expression of Smac and Survivin was evaluated by reverse transcription-polymerase chain reaction (RT-PCR) in HCC tissues of 50 patients, para-carcinoma tissues of 20 patients, and normal liver tissues of 15 patients. RESULTS: Smac mRNA was detected by RT-PCR in HCC tissues of 21 (42.0%) of the 50 patients, para-carcinoma tissues of 19 (95.0%) of the 20 patients, and normal liver tissues of 15 (100%) of the 15 patients. Survivin mRNA was found in HCC tissues of 46 of the 50 patients, para- carcinoma tissues of 2 of the 20 patients, and normal liver tissues of 0 of 15 patients. Immunohistochemistry revealed Smac protein in HCC tissues of 20 patients (40.0%), in para-carcinoma tissues of 18 patients (90.0%), and normal liver tissues of 15 patients (100.0%). The expression of Smac was significantly different in HCC tissues and non- HCC tissues. Survivin protein was found in HCC tissuesin 45 patients, para-carcinoma tissues in 2 patients, and normal liver tissues in none of the patients. The expression of Survivin was significantly different in HCC tissues and non-HCC tissues. CONCLUSION: Smac inhibits apoptosis of HCC cells by suppression of Survivin, and the two genes probably form an important link in the
文摘The second mitochondria-derived activator of caspases (Smac) is a novelproapoptotic gene, which plays an important role in the apoptosis-inducing effects of irradiation ontumor cells. The purpose of this study was to investigate the effects of extrinsic Smac genetransfer and its over-expression in radiotherapeutic sensitivities of cervical cancer cells. Afterthe Smac gene was transferred into the cervical cancer cell line HeLa, subcloned cells were obtainedby persistent G418 selection. Cellular Smac gene expression was detected by RT-PCR and Westernblot, while in vitro cell viabilities were detected by trypan blue staining assay. After treatmentwith X-ray irradiation, cellular radiotherapeutic sensitivities were investigated by tetrazoliumbromide colorimetry. Cellular apoptosis and its rate were determined by electronic microscopy,annexin V-FITC and propidium iodide staining flow cytometry. The expression and activities ofcellular caspase-3 were assayed by Western blot and colorimetry. Smac mRNA and protein levels inHeLa/Smac cells and the selected subclone cell line of cervical cancer were significantly higherthan those of HeLa (P <0. 01). There was no significant difference in cellular viabilities betweenthem (P > 0. 05 ) . However, after irradiation with 8 Gy X-ray, growth activities of HeLa/ Smac werereduced by 22.42% (P < 0. 01). When compared with those of HeLa, partial HeLa/Smac cells presentedcharacteristic morphological changes of apoptosis under electronic microscope, with higher apoptosisrates (16. 4% vs. 6. 2% , P < 0. 01 ) ; the caspase-3 expression levels in HeLa/Smac cells wereimproved significantly (P <0. 01) , while its activities were increased by 3. 42 times (P <0. 01).Stable transfer of the extrinsic Smac gene and its over-expression in cervical cancer cell linecould significantly enhance the expression and activities of cellular caspase-3 and ameliorateapoptosis-inducing effects of irradiation on cancer cells, which was a novel strategy to improveradiotherapeutic effects on cervical cancer.
