Scientists have now discovered how cancer cells are able to spread to distant parts of the body. It was previously though that these cells spread to the target site via the blood or the lymph and then started forming a new tumor there.
It has now emerged that certain chemicals secreted by the tumors do the job of preparing the potential "landing" site by altering the conditions to make them ideal for cancer growth. Researchers from the Cornell University's Weill Medical College in New York have published their findings in today's issue of the journal Nature. Their study demonstrates that cancer cells induce certain bone marrow cells to migrate to distant organs and prepare the site for further colonization by the tumor. If these bone marrow cells can be blocked by drugs, then the spread of cancer, which is what makes the disease so deadly can be easily contained, "These nests provide attachment factors for the tumor cells to implant and nurture them. It causes them not only to bind but to proliferate. Once that all takes place we have a fully formed metastatic site or secondary tumor," said Lead researcher Dr David Lyden. He added that for the first time the initial steps involved in metastasis were mapped out. "By blocking bone marrow cells using antibodies, we are capable of preventing tumor cells implanting and thus the spread of cancer," he observed.
The current study shows that the initial protein that is sent out as an emissary is fibronectin. Once it has entrenched into the area, a second growth factor arrives and thus bone marrow cells can easily colonize this area. Once this happens, malignant cells that arrive later have a foundation that can begin the formation of secondary cancer. These steps were shown in mice, whose bone marrow cells were killed by irradiation. The researchers then injected skin cancer and lung cancer cells into these mice after supplying bone marrow cells tagged with green fluorescent protein. This enabled them to track the progress of the cells in the body. The cancer cells were tagged with red fluorescent protein. The researchers found that green cells appeared in the lungs many days before the actual tumor cells arrived, thus signaling that they were preparing the site for invasion of the cancer cells.