Acetylcholinesterase In The Preliminary Study Of Changes In Apoptosis In Pc12 Cells And Matrine Molecular Mechanisms That Induce Apoptosis Of K562 Cells

The acetylcholinesterase (AChE) was reported being upregulated during the apoptosis of cell lines from different origin. AChE was supposed possess the apoptosis provoking function. In order to investigate how and what caused the acetylcholinesterase (AChE) change in the cell lines with endogenous AChE expression, we carried out our experiments with neuronal-like PC12 cells, which have stable R and T AChE subunits expression. Hydrogen peroxide induced AChE activity increase up to twice in PC12 cells and the emergence of a short-form AChE which came from the cleavage of full length AChE. Glutathione inhibited the increase in AChE activity and protein level, suggesting that reactive oxygen species play a key role in this process. Further investigation indicated that the AChE increase was later than the decrease of the level of Akt and phosphorylated Akt, the release of cytochrome c from mitochondria into the cytosol and activation of caspase family members. The tranfection of constitutively activated Akt, NGF or caspase inhibitor incubation maintained the Akt level, delayed mitochondrial collapse and the AChE activity increase. The emergency of truncated AChE fragment was dependent on caspase activation. But the AChE cleavage was not detected in apoptotic 293T cells with transfected AChE. Thus it needs further investigation whether the PC12 cells possessed specific mechanisms controlling the caspase dependent AChE cleavage.Matrine induced apoptosis and parallel increase on AChE activity in K562 cells, which have endogenous AChE H subunit expression. But the AChE change was not detected in all matrine induced apoptotic cells. Thus we primarily investigated the apoptotic signal cascades in matrine induced apoptotic K562 cells. We found that the p53 level was undetectable in K562 cells before or after matrine incubation. Further analysis of matrine-induced apoptotic changes revealed that E2F-1 and Apaf1 were up regulated, whereas Rb was down regulated after 24 hours of exposure. This was followed by Bax translocation, cytochrome c release, and caspase-9 and -3 activation. And co-treatment with etoposide potentiated apoptosis. These results demonstrate that matrine triggers apoptosis of K562 cells primarily through the mitochondrial pathway and that matrine is a potential anti-tumor drug.