Tumor angiogenic activity (TAA) production in vitro and growth in the nude mouse by human malignant melanoma.

The production of angiogenic activity by eleven human melanoma lines in vitro was compared with the extent of tumor growth in the nude mouse. Angiogenic activity was assayed by measuring the vascular response of the chick chorioallantoic membrane to serum-free supernatants. Growth in the nude mouse was determined after subcutaneous injection of cells 60 days later. Angiogenic activities ranged from negative to highly positive. In five lines angiogenic activity in vitro correlates with the extent of tumor growth in the nude mouse. In contrast, two lines did not show such a correlation, e.g. they produced large tumours without any detectable angiogenic activity. Histological examination of these two tumors revealed moderate degrees of vascularization and only low degrees of necrosis. It is concluded that the extent of tumor growth in the nude mouse is partly independent of the production of angiogenic activity by the tumor cells themselves.