Cyclin-dependent kinase 2 activated by cyclin E in breast cancer cells.

2004 JUN 3 - (NewsRx.com & NewsRx.net) -- Cyclin-dependent kinase 2 is activated by full length and low molecular weight forms of cyclin E in breast cancer cells.

According to a study from the United States, "Cyclin E, a positive regulator of the cell cycle, controls the transition of cells from G[subscript]1 to S phase. Deregulation of the G[subscript]1-S checkpoint contributes to uncontrolled cell division, a hallmark of cancer. We have reported previously that cyclin E is overexpressed in breast cancer and such overexpression is usually accompanied by the appearance of low molecular weight isoforms of cyclin E protein, which are not present in normal cells."

"Furthermore, we have shown that the expression of cyclin E low molecular weight isoforms can be used as a reliable prognostic marker for breast cancer to predict patient outcome," said Richard M. Harwell and collaborators at State University of New York-Albany and the University of Texas. "In this study we examined the role of cyclin E in directly activating cyclin-dependent kinase (CDK) 2. For this purpose, a series of N-terminal deleted forms of cyclin E corresponding to the low molecular weight forms detected only in cancer cells were translated in vitro and mixed with cell extracts. These tumor-specific N-terminal deleted forms of cyclin E are able to activate CDK2.

"Addition of cyclin E into both normal and tumor cell extracts was shown to increase the levels of CDK2 activity, along with an increase in the amount of phosphorylated CDK2," reported Harwell and his colleagues. "The increase in CDK2 activity was because of cyclin E ...