Could breast cancer cells have a cannibalistic side that leads to disease recurrence?

To the surprise of researchers, breast cancer cells were observed to essentially eat the body’s own stem cells, in a recent study published in the Proceedings of the National Academy of Sciences.

While the research team was working to teach mesenchymal stem/stromal cells (MSCs) to fight cancer, they realized that the MSCs were disappearing from the cell cultures.

“We actually though we made a mistake or were witnessing an anomaly or negative result,” said first study author Thomas J. Bartosh, PhD. “We eventually realized that the breast cancer cells were eating the stem cells. What was really interesting was what happened next: The breast cancer cells that had taken in the stem cells went dormant – essentially became ‘sleepy’ – but at the same time they became much more difficult to kill.”

Upon seeing this behavior in the cell cultures, the researchers realized that if breast cancer cells act the same way in the human body, it may be an explanation for cancer recurrence.

Cancer cells that have cannibalized MSCs become highly-resistant to chemotherapy and nutrient deprivation, which can kill other cancerous cells. Although only a few cannibalistic cells survive, existing scanning methods are unable to detect them.

“Then one day, when conditions are right, the cells ‘wake up’ and start growing again,” Bartosh said. “This is when the cancer recurs, and because the cells are treatment-resistant, the recurrence can be very difficult to combat.”

Since a potential mechanism for recurrence has been explained, the researchers hope that a future treatment can be developed that safely keeps cannibalistic cells dormant for the rest of patients’ lives.

For now, the researchers are working to exploit the cannibalistic activity of cancer cells to potentially feed them toxic agents with MSCs as the delivery vehicle to target the cells.

“The biology of the process is intriguing,” Bartosh said. “It’s one mysterious phenomenon – cell cannibalism – that might help explain another mysterious phenomenon: tumor dormancy. If these findings do translate to humans, the implications for patients would be enormous.”