Leftovers of cell division spread cancer's genetic blueprint
Researchers have found that remnants left over after a cell divides contain RNA that, when taken up by other cells, can spread cancer’s genetic blueprint. The finding opens the door to harnessing this mechanism as a way of treating cancer.
During the final stages of cell division, or mitosis, a transient intercellular ‘bridge’ called a midbody connects the two daughter cells, recruiting and positioning the machinery that eventually separates them.
Originally, it was thought that what’s left of the midbody after cellular separation – the midbody remnant – immediately degraded. However, recent studies have found that midbody remnants are released and may contribute to the proliferation of tumor and stem cells. A new study led by researchers at the University of Wisconsin-Madison examined the contents, organization and behavior of midbodies to gain a better understanding of what they do in the body.
“People thought the midbody was a place where things died or were recycled after cell division,” said Ahna Skop, corresponding author of the study. “But one person’s trash is another person’s treasure. A midbody is a little packet of information cells use to communicate.”
They found that the midbody RNA produced proteins that are involved in directing a cell’s purpose, including its ability to differentiate (pluripotency) and to form cancerous tumors (oncogenesis). The finding points to the midbody as a vehicle for the spread of cancer in the body.
“One cell divides into three things: two cells and one midbody remnant, a new signaling organelle,” said Ahna Skop, corresponding author of the study. “What surprised us is that the midbody is full of genetic information, RNA, that doesn’t have much to do with cell division at all, but likely functions in cell communication.”
Many midbody remnants are absorbed by one of the daughter cells they were instrumental in separating, but if they escape, they can be absorbed by another cell and mistakenly begin using the midbody RNA as if it were its own blueprints.
“A midbody remnant is very small,” Skop said. “It’s a micron in size, a millionth of a meter. But it’s like a little lunar lander. It’s got everything it needs to sustain that working information from the dividing cell. And it can drift away from the site of mitosis, get into your bloodstream and land on another cell far away.”
Previous research has shown that among normal dividing cells, stem cells and cancer cells, cancer cells are more likely to accumulate midbodies, correlating with increased proliferation and tumor-growing behavior.
The researchers were also able to identify a gene, called Arc, which is key to loading RNA into the midbody and midbody remnant. Arc has also been linked to molecular processes in the brain associated with learning and memory.
“Loss of Arc leads to the loss of RNA in the midbody and a loss of the RNA information from getting to recipient cells,” said Skop. “We believe this memory gene is important for all cells to communicate RNA information.”
The researchers say that further research may harness the power of midbody RNA to enable drug delivery directly to cancer cells or stop them from dividing.
“We think our findings represent a huge target for cancer detection and therapeutics,” said Skop.
The study was published in the journal Developmental Cell.
Source: University of Wisconsin-Madison