Scope: Cell cycle regulation is a critical issue in cancer treatment. Previously, gallic acid (GA)
has been reported to possess anticancer ability. Here, we have evaluated the molecular
mechanism of GA on cell cycle modulation in a human bladder transitional carcinoma cell
line (TSGH-8301 cell).
Methods and results: Using flow cytometer analysis, exposure of the cells to 40 mM GA
resulted in a statistically significant increase in G2/M phase cells, which was accompanied by
a decrease in G0/G1 phase cells. GA-treated cells resulted in significant growth inhibition in a
dose-dependent manner accompanied by a decrease in cyclin-dependent kinases (Cdk1),
Cyclin B1, and Cdc25C, but significant increases in p-cdc2 (Tyr-15) and Cip1/p21 by western
blotting. Additional mechanistic studies showed that GA induces phosphorylation of Cdc25C
at Ser-216. This mechanism leads to its translocation from the nucleus to the cytoplasm
resulting in an increased binding with 14-3-3b. When treated with GA, phosphorylated
Cdc25C can be activated by ataxia telangiectasia-mutated checkpoint kinase 2 (Chk2). This
might be a DNA damage response as indicated by Ser-139 phosphorylation of histine H2A.X.
Furthermore, treatment of the cells with a Chk2 inhibitor significantly attenuated GAinduced
G2/M phase arrest.
Conclusion: These results indicate that GA can induce cell cycle arrest at G2/M phase via
Chk2-mediated phosphorylation of Cdc25C in a bladder transitional carcinoma cell line.
