Role of G2/M Checkpoint Controls in Cytotoxic Treatment of Breast Cancer

摘要

The objective of the work is to provide a detailed understanding of the molecular mechanism by which G2/M regulation is achieved in human cells. In particular we are focusing on how initiation of M-phase is delayed in cells that have been treated with agents that induce DNA damage or that prevent synthesis of DNA. By providing a more detailed explanation of how cytotoxic therapies brings about cell death we hope to provide clinicians with better tools for the treatment of breast cancer. Human cell-lines that over-express non- phosphorylatable mutants of Cdc2 were used to establish the importance of inhibitory phosphorylation of Cdc2 in checkpoint control in human cells. Evidence for changes in the activity of the enzymes that regulate phosphorylation of Cdc2 was sought in cells that had been subjected to DNA damage by irradiation. We found that the activity of Cdc25, the phosphatase that activates Cdc2, is decreased in response to damaged DNA. We have identified two human kinases that phosphorylate and inactivate Cdc25 directly in vitro. These two kinases are likely to be important therapeutic targets. Further understanding of the regulation and function of these checkpoint kinases will improve understanding of current anti-cancer therapy and is likely to provide the bases for development of novel therapies.