Excessive production of transforming growth-factor beta 1 can play an important role in the development of tumorigenesis by its action for angiogenesis: validity of neutralizing antibodies to block tumor growth.

Angiogenesis is an important part of tumor growth in vivo. We used the transfected Chinese hamster ovary (CHO) cells that overproduced recombinant transforming growth-factor beta 1 (TGF-beta 1) to examine the possible role of this factor in tumor growth and angiogenesis in a nude mouse model. The in-vitro proliferation of TGF-beta 1-transfected CHO cells was unaffected by the treatment of either recombinant TGF-beta 1 or an anti-TGF-beta 1 antibody. The TGF-beta 1-transfected cells grew more rapidly than the parental CHO cells when injected subcutaneously into nude mice. The tumors derived from the TGF-beta 1-transfected cells showed prominent tumor-associated angiogenesis, whereas the parental cells produced tumors without such angiogenesis. In addition, an anti-TGF-beta 1 neutralizing antibody was able to inhibit both growth and angiogenesis in the tumors derived from TGF-beta 1-transfected cells. These findings suggest that the overproduction of TGF-beta 1 by tumor cells can contribute to neovascularization and may help promote tumor development in vivo.