Scientists have discovered molecules that can determine whether cancer tumors will spread to other parts of the body. As this ScienCentral News video explains, the tiny molecules prevent tumors from spreading.
Why Do Some Tumors Spread?
Cathe Sheehan, an independent computer consultant, has battled breast cancer for two years. Her doctor told her that even after having the tumor removed, chances of recurrence were high.
“The whole thing is very overwhelming. It was so unexpected and so much of it just sort of kept reeling out of control in my head,” recalls Sheehan.
The cancer did recur in the same spot and Sheehan endured a double mastectomy last December, in order to stop its spread.
Memorial Sloan-Kettering Cancer Center researcher Sohail Tavazoie says that when a cancer cell develops the ability to spread to other organs, “it is the deadliest transformation that can occur.” Tavazoie, Joan Massague, and colleagues conducted a research study to find out why some cancer cells spread, or metastasize, and others do not.
Studying human breast cancer cells in mice, they looked for the differences between the most aggressive cancer cells, which spread to bone and lung, and the less aggressive ones. They found that the most aggressive tumor cells were missing three tiny pieces of genetic material called microRNA. They are called miR-335, miR-126 and miR-206. When the researchers replaced the microRNAs into the cells, the cancer cells lost their ability to spread.
The scientists wanted to find out if the same thing happens in people. So they studied breast cancer tumors that had been removed from women and looked at which women experienced a spread to other organs.
“We found that women who lacked these microRNAs [in their tumors] were much more likely to have their cancer spread than those who possessed these microRNAs,” says Tavazoie.
Tavazoie believes the microRNAs, which turn off specific genes in cells, act as brakes in normal cells. “When they are lost it’s sort of similar to the brake being gone so that a cell can both grow more rapidly and spread more effectively,” he says.
Indeed, his team found that one of the three microRNAs they studied, miR-335, blocked the activity of six genes and its loss led to greater ability of the cancer to spread.
“The activity of these six genes appear to be elevated in the aggressive breast cancers,” he explains. “So we believe that these six genes could be added to the list of other genes that researchers have identified as being important for the spread of cancers.”
“MicroRNAs have been of great interest to the scientific community over the last few years,” says Tavazoie. “People have shown an important role for microRNAs in cancers such as lymphoma and also testicular cancer, and they’ve shown that they’re important for controlling the growth of cancer cells. And our work shows that another aspect of cancer biology â€” in this case the spread of cancer â€” is also regulated by these microRNAs,”
Tavazoie, who is not only a researcher, but also treats cancer patients, hopes his findings will one day directly benefit people.
“We envision that these microRNAs that we’ve identified â€” and others that we believe will be identified in other cancers â€” could be used by clinicians in the future to identify patients at highest risk for the spread of cancer,” he says.
And he believes that identifying these patients will lead to development of new drugs that act against the molecules that promote the spread of breast cancer.
In the meantime, Cathe Sheehan is grateful that her cancer was detected early. And she is looking forward to March when she turns 50. She says that keeping up with the progress in cancer research reassures her.
Sheehan explains, “That’s the difference between ‘I’m not going to be looking forward to the future’ and, ‘Oh, I’m really glad they’re looking at this,’ okay? I am hopeful because I have this kind of information arsenal that’s helping back up my hopefulness. It gives me the foundation to be hopeful.”
PUBLICATION: Nature, January 10, 2008
Study Authors: Sohail F. Tavazoie, Claudio Alarcon, Thordur Oskarsson, David Padua, Qiongqing Wang, Paula D. Bos, William L. Gerald and Joan Massague
RESEARCH FUNDED BY: National Institutes of Health, Howard Hughes Medical Institute, Olson Foundation, Hearst Foundation, and Kleberg FoundationShare Post: | Stumble | Share on Facebook | Tweet This |