BACKGROUND: It has been previously demonstrated that bufalin, an active agent in the Chinese medicine chan'su, induces apoptosis in human leukemia cells by altering the expression of apoptosis-related genes, such as bcl-2 and c-myc. Tiam1 was also found to play a critical role in bufalin-induced apoptosis through the activation of the Rac1, PAK and JNK pathway in human leukemia cell lines. In the present study, the involvement of the Tiam1 gene products in bufalin-induced apoptosis in human solid tumor HeLa cells was examined. MATERIALS AND METHODS: HeLa cells were treated with 10(-8) M bufalin and apoptosis was measured by ELISA quantification of nucleosomes. Tiam1 mRNA levels were quantified by real-time PCR analysis and inhibited by transfected siRNA specific for Tiam1. RESULTS: Apoptosis was induced in HeLa cells by treatment with 10(-8) M bufalin. Expression of both Tiam1 mRNA and its protein was induced 0.5 h after the start of the bufalin treatment. Transfection of Tiam1-specific siRNA into HeLa cells markedly inhibited bufalin-induced apoptosis. CONCLUSION: Our results suggest that Tiam1 is a downstream mediator of bufalin-induced apoptosis in the human solid tumor HeLa cell line, as well as in leukemia cell lines.
BACKGROUND: It has been previously demonstrated that bufalin, an active agent in the Chinese medicine chan'su, induces apoptosis in humanleukemia cells by altering the expression of apoptosis-related genes, such as bcl-2 and c-myc. Tiam1 was also found to play a critical role in bufalin-induced apoptosis through the activation of the Rac1, PAK and JNK pathway in humanleukemia cell lines. In the present study, the involvement of the Tiam1 gene products in bufalin-induced apoptosis in human solid tumor HeLa cells was examined. MATERIALS AND METHODS: HeLa cells were treated with 10(-8) M bufalin and apoptosis was measured by ELISA quantification of nucleosomes. Tiam1 mRNA levels were quantified by real-time PCR analysis and inhibited by transfected siRNA specific for Tiam1. RESULTS: Apoptosis was induced in HeLa cells by treatment with 10(-8) M bufalin. Expression of both Tiam1 mRNA and its protein was induced 0.5 h after the start of the bufalin treatment. Transfection of Tiam1-specific siRNA into HeLa cells markedly inhibited bufalin-induced apoptosis. CONCLUSION: Our results suggest that Tiam1 is a downstream mediator of bufalin-induced apoptosis in the human solid tumor HeLa cell line, as well as in leukemia cell lines.