Metastasis is a major problem with cancer because it allows tumor cells to spread to other parts of the body (See Supporting Material: Cancer and Metastasis). While solid tumors can be removed surgically or treated with chemotherapy or radiation, metastatic cells that have already entered the circulation are capable of opening a passageway through blood vessels in order to spread to various organs throughout the body.
Once tumor cells leave their primary tumor, they enter the blood stream and ultimately must find an exit strategy in order to set up new "satellite" lesions in one or more distant organs. The potential treatment strategy targets this final step of the metastatic cascade--the exit of the metastatic cells from the bloodstream.
"We know that the normal blood vessel wall is one final barrier that metastatic tumor cells must overcome, which allows them to find their way out of the bloodstream and into a metastatic site," says Immunology Professor David A. Cheresh, who led the research with postdoctoral fellow Sara Weis at The Scripps Research Institute. To exit the blood stream, says Cheresh, the tumor cells stimulate the local blood vessels to briefly open their cell-cell junctions so that they can implant themselves into a new organ site.
In the latest issue of the Journal of Cell Biology, Cheresh, Weis, and their colleagues report the dramatic effect of using a class of compounds known as Src kinase inhibitors to treat metastatic cancer in mice. Rather than conventional chemotherapies, which target the tumor cells, Cheresh and colleagues suggest a new approach that would increase the protective barrier strength of the host blood vessels and prevent tumor cells from exiting the bloodstream.