They both share information through a system of social communication, according to a study published last week by a team of Israeli and American scientists. According to the researchers, cancer cells cooperate and correspond by directing each other to parts of the body where they can settle and metastasize. This method of communication is similar to that already proven to exist between bacteria.
The researchers, led by physicist and biocomplexity expert Professor Eshel Ben-Jacob of Tel Aviv University's School of Physics and Astronomy, cancer researcher Professor Donald Coffey of John Hopkins University, and Professor Herbert Levine of Rice University, published their findings in the “Trends in Microbiology” journal. In it, they describe the similarities between bacteria and cancer cells, and explain how a "social network" is created to speed up the cells' reproduction in the body.
Healthy human cells are considered "obedient": They function and evolve in accordance with chemical and physical cues. In contrast, bacteria and cancer cells sidestep these methods in order to reproduce while ignoring the body's immune system and sending misleading messages that affect its function. By communicating between themselves, cancer cells are able to share resources within the body, divide and "make decisions," as the researchers put it.
"Before cells are sent to settle in parts of the body or in human tissue, 'spying cells' are sent to scan the body, and help other cells navigate from the source of the tumor to the area where they will settle for the purpose of metastasizing," Ben-Jacob says.
Studies have shown that cancer cells do not settle in just any human tissue, but instead carefully choose where they will develop, and prepare that site by sending signals to one another. This is similar to the behavior displayed by bacteria, which are generally dispatched to scan an area before returning to the original colony to report on the information they accumulated.
In addition, in a similar fashion to bacteria, cancer cells also affect the environment around them, creating genetic changes in adjacent healthy cells that serve to protect them. Like bacteria, cancer cells are likely to become dormant when they sense danger – such as that posed by chemotherapy – and can reactivate once the threat has passed if they survive the treatment.
"For years scientists have ignored the complexity of the social relationships between bacteria, which is currently the third largest cause of death in hospitals in the Western world," says Ben-Jacob. "Since the '60s there has not been any significant change in the life expectancy of cancer patients. Perhaps it's time to change the way we approach the disease."
The researchers call future treatments against cancer to take into consideration the cancer cells' social behavior. "It will be possible to overcome the cancer cells by using their 'social intelligence,'" the researchers wrote.
According to Ben-Jacob, "Recognizing this new approach to cancer cells may inspire new directions for research, such as developing new drugs that would target the mechanisms cancer cells use to communicate with each other. This can be used to disrupt communications, and prevent the growth of the tumor."
In past studies Ben-Jacob conducted among bacteria colonies, he studied the "cannibalism" phenomenon, which causes bacteria to kill each other, and cracked the communication code that transmits messages that encourage this behavior. Taking a cue from this, the researchers suggest that cannibalism among cancer cells, manifested in their tendency to engulf adjacent cancerous cells when they run out of resources, also be studied. "It is possible to take advantage of the communications mechanism between cancerous cells to compel them to destroy each other in this way," says Ben-Jacob.
Future studies in the struggle against cancer are likely to take advantage of the similarities between cancer cells and bacteria. Past research has already shown that bacteria are able to stimulate the body's immune system to fight cancer. "It's possible that we're entering into a new age of 'biological cyber-warfare,' where scientists can enlist bacterial intelligence to defeat cancerous tumors and send cancerous cells misleading messages, to confuse them and disrupt communication, similar to the strategies used in war," concludes Ben-Jacob.
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