Sulforaphane-induced G2/M Phase Cell Cycle Arrest Involves Checkpoint Kinase 2-mediated Phosphorylation of Cell Division Cycle 25C

作者：Shivendra Vikram Singh, Anna Herman-Antosiewicz, Ajita Singh, Karen L. Lew, Sanjay Kumar Srivastava, Ravindra Kamath, Kevin D. Brown, Lin Zhang, Baskaran Rajasekaran · 发表于：Journal of Biological Chemistry · 年份：2004 · DOI：10.1074/jbc.m313538200 · 被引用次数：348 · 研究领域：Genomics, phytochemicals, and oxidative stress、Acute Lymphoblastic Leukemia research、Glutathione Transferases and Polymorphisms

Previously, we showed that sulforaphane (SFN), a naturally occurring cancer chemopreventive agent, effectively inhibits proliferation of PC-3 human prostate cancer cells by causing caspase-9- and caspase-8-mediated apoptosis. Here, we demonstrate that SFN treatment causes an irreversible arrest in the G(2)/M phase of the cell cycle. Cell cycle arrest induced by SFN was associated with a significant decrease in protein levels of cyclin B1, cell division cycle (Cdc) 25B, and Cdc25C, leading to accumulation of Tyr-15-phosphorylated (inactive) cyclin-dependent kinase 1. The SFN-induced decline in Cdc25C protein level was blocked in the presence of proteasome inhibitor lactacystin, but lactacystin did not confer protection against cell cycle arrest. Interestingly, SFN treatment also resulted in a rapid and sustained phosphorylation of Cdc25C at Ser-216, leading to its translocation from the nucleus to the cytoplasm because of increased binding with 14-3-3beta. Increased Ser-216 phosphorylation of Cdc25C upon treatment with SFN was the result of activation of checkpoint kinase 2 (Chk2), which was associated with Ser-1981 phosphorylation of ataxia telangiectasia-mutated, generation of reactive oxygen species, and Ser-139 phosphorylation of histone H2A.X, a sensitive marker for the presence of DNA double-strand breaks. Transient transfection of PC-3 cells with Chk2-specific small interfering RNA duplexes significantly attenuated SFN-induced G(2)/M arrest. HCT116 human colon cancer-de...