CELL DIVISION Method reverses process

One expert said time is an issue in the process.
SCRIPPS HOWARD
The process of a parent cell dividing its genetic code into two identical daughter cells has always been thought to be a one-way street -- once the cells begin the splitting process, there was no way to stop it.
But in a discovery that could have important implications for treating cancer, birth defects and other conditions, scientists report Thursday that they've found a way to control a key protein responsible for such division, and thus reverse the process.
By manipulating the protein, called Cdk1, researchers from the Oklahoma Medical Research Foundation and the University of Virginia found they were able to interrupt the dividing.
"No one has gotten the cell cycle to go backwards before now," said Gary Gorbsky, a researcher into developmental biology at the foundation and lead author of the study, published in the journal Nature. "This shows that certain events in the cell cycle that have long been assumed irreversible may, in fact, be reversible."
Gorbsky's lab has been focused on the mechanisms of how chromosomes assemble and move during cell division, and particularly the checkpoint system that prevents chromosomes from segregating in new cells until the DNA strands are all properly in place.
In cancer cells, this checkpoint system is often faulty, leading to the generation of cells with too many, or too few, chromosomes, and produces abnormal cells with malignant characteristics.
Team's goal
Gorbsky's team has been looking for compounds that can precisely target defective components of this pathway, thus shutting down the proliferation of cancer cells. The work with the protein is a part of this effort.
Cell division occurs millions of times each day in the human body, part of the normal replacement of aging cells in most organs and tissues. By using a substance that inhibited Cdk1's normal function, Gorbsky halted the division process after the point where separate bundles of chromosomes had formed, but before new cell walls had become established, and sent the duplicate chromosomes back to the center of the original cell.
"The factors pointing cells toward division can be turned and even reversed," Gorbsky said. "If we wait too long, however, it doesn't work, so we know that there are multiple regulators in the cell-division cycle that inhibit backtracking. Now, we will begin to study the triggers that set these events in motion."
The research, sponsored by the National Institutes of Health and the American Cancer Society, most immediately could lead to advances in preventing the development and spread of certain types of cancer cells in the body.