Involvement of Tiam1 in apoptosis induced by bufalin in HeLa cells
Cao-Hong; Shibayama-Imazu, T.; Masuda, Y.; Shinki, T.; Nakajo, S.; Nakaya, K.
Anticancer Research 27(1a): 245-249
2007
ISSN/ISBN: 0250-7005 PMID: 17352239 Document Number: 613848
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 apoplosis-related genes, such as bcl-2 and c-myc. Tiam I 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.