New Form of Cell Division Found

Natural Back-Up Mechanism for defective cell division

Researchers at the University of Wisconsin Carbone Cancer Center have discovered a new form of cell division in human cells.
They think that will act as a backup mechanism for cell division errors, prevents some cells from going down a path that can lead to cancer.
"If we could promote this new form of cell division called klerokinesis, we may be able to prevent certain types of cancer in developing countries," said lead researcher Dr. Mark Burkard, assistant professor of hematology-oncology at the School of Medicine University of Wisconsin School of Medicine and Public Health.
Burkard presented the findings on Dec. 17 at the annual meeting of the American Society for Cell Biology in San Francisco.
A medical researcher who see patients with breast cancer, cancer Burkard studies where cells contain too many chromosomes, a condition known as polyploidy.
About 14 percent of breast cancer cases and 35 percent of pancreatic cancers are three or more sets of chromosomes rather than two normal sets. Many other types of cancer cells containing chromosomes are defective and not too many or too few.
"Our goal in the laboratory has been to find ways to develop new treatment strategies for breast cancer with too many sets of chromosomes," he says. The original aim of the study was to make human cells that have extra sets of chromosomes. But after following the accepted pattern was observed unexpectedly new form of cell division.
So far, most Burkard and cellular biologists today accepted a century old hypothesis developed by the German biologist Theodor Boveri, who studied egg urchin populations. Boveri assumed that the error of cell division that leads to cells with abnormal chromosome set, then the uncontrolled growth of cancer cells defined. Evidence accumulated over the years, most researchers have come to accept the hypothesis.
Normal cell division is at the heart of the ability of an organism to grow from a single fertilized egg into a fully developed individual. More than a million rounds of division million to spend to make this happen. In each division, a stem cell daughter cells. Even in a fully grown adult, many types of cells routinely recreated through cell division.

The basic process of copying the cells start phase synthesis, when a copy is made of cellular components including DNA-containing chromosomes in the nucleus. Then, during mitosis, the two sets are physically separated in opposite directions, while still contained in a cell. Finally during cytokinesis, the cell of a cut into two daughter cells, just at the end of mitosis.
Burkard and his team made the cells more chromosomes - mimic cancer. The researchers blocked cytokinesis with a chemical and waited to see what happened.
"It is expected to recover a number of cells with abnormal chromosome set," Burkard said.
The researchers found that instead appears abnormal daughter cells ended up looking more normal time. Unlike Bovver hypothesis, abnormal cell division rarely had long-term adverse effects in human cells.
So the group decided to see how human cells restored normal set of chromosomes observed with a microscope that had the ability to take video.
"We started with two nuclei in a cell," said Burkard. "To our great surprise, as it appears each cell into two cells without going through mitosis."
Each of the two new cells inherit the intact core surround a complete set of chromosomes. Split occurred unpredictably, during a phase of growth retardation rather than at the end of mitosis.
The researchers conducted a series of experiments to check carefully that the division observed was different from cytokinesis.
"We easily convinced ourselves, because this type of division is not in any textbook," Burkard said.
Eventually, we found that only 90 percent of the daughter cells had found a normal complement of chromosomes. Burkard want to exploit the statistics up to 99 percent.
"If we could push the cell against this new kind of division, we may be able to keep normal cells and a lower incidence of cancer," he says.
Burkard now believe that among all the rounds of cell division, the organization carries out, from time to time may fail cytokinesis. And this new division is a backup mechanism that allows cells to recover from the collapse and grow normally.
The group has called the new type of division to distinguish klerokinesis cytokinesis. Burkard was assisted by Dr. William Brockliss, UW assistant professor of classics, to get the name, klero is a Greek prefix meaning "inheritance assigned."
Project partners are Dr. Beth Weaver, UW assistant professor of cell biology and regeneration, Dr. Alka Choudhary, Lera Robert, Dr. Melissa Martowicz and Dr. Jennifer Laffin.