NEW YORK, Sep 28 (Reuters Health) -- A substance produced by certain cancers that prevents the cancer from 'seeding' to other sites in the body may offer hope as a new cancer therapy, suggest researchers.
Certain tumors produce transforming growth factor-beta-1 (TGF-beta-1), which in turn prevents the growth of new blood vessels and inhibits the formation of secondary tumors (metastases).
Therapies that affect TGF-beta-1 levels could be effective in limiting the development of metastases as well as affect the growth of tumors, according to Dr. Rakesh Jain from the Massachusetts General Hospital and Harvard Medical School in Boston, and colleagues. Their report is published in the October issue of Nature Medicine.
In order to continue to grow and spread, tumors often produce factors that enhance new blood vessel formation, or angiogenesis, to provide nutrients to the expanding tumor. Inhibiting angiogenesis might reduce the tumor's chances of survival or spread to other locations. Knowing that some tumors also create an anti-angiogenic environment, the investigators sought factors that might be involved in preventing angiogenesis.
The research team reports that mice with tumors in their gallbladders produce amounts of TGF-beta-1 three times higher than in mice with no tumors or in mice with tumor cells implanted just beneath their skin. On the other hand, levels of other potential anti-angiogenesis factors did not differ among the mouse groups.
Additional studies demonstrated that TGF-beta-1 not only inhibited angiogenesis but also reduced tumor cell proliferation at sites distant from the main gallbladder tumor, according to the results.
Blocking TGF-beta-1 with antibody treatment reversed the anti-angiogenesis effect but did not alter the tumor growth suppression, the investigators note.
The researchers report that TGF-beta-1 released by gallbladder tumors could be involved in suppressing metastases and, possibly, in affecting the growth of the tumor that produces it.
These findings suggest that therapies that modify TGF-beta-1 levels might prove effective in controlling the growth and spread of tumors, Jain and colleagues conclude.
This is the first time that the effects of tumor-produced TGF-beta-1 on angiogenesis distant from the main tumor have been investigated, the authors note.
