[Effects of Tcd A on Rho GTPases and the Cytoskeleton of Leukemia Cell Line K562].

OBJECTIVE: To investigate the effect of clostridium difficile toxin A(TcdA) on the Rho GTPases and the cytoskeleton in K562 cells. METHODS: K562 cells were cultured in vitro with different concentration of TcdA.The effect of TcdA proliferation of cells was detected by MTT method after the K562 cells were stimulated with TcdA for 24,48 and 72h; the expression of cdc42, RhoA, Rac1 mRNA was assessed by RT-PCR; the changes of the microtubule, the microfilament were observed by confocal laser scanning microscopy. RESULTS: The proliferation of K562 cells was inhibited after exposure to TcdA for 24, 48 and 72h, and the inhibitory rate was 47.67% in the treatment for 48 h. the cdc42，RhoA and Rac1 mRNA expressions in the experimental groups decreased after treated with TcdA(P<0.05), which positively correlated with concentration of TcdA. Also, the microfilament decreased ,which was observed by confocal laser scanning microscopy. CONCLUSION: TcdA inhibites K562 cell proliferation and induces apoptosis, TcdA can change the cytoskeleton structure through the cytoskeletal protein genes cdc42 and RhoA, Rac1 mRNA expression,. It is related with cell microfilament content decreasing.