Angiogenesis Factor Activates

Avascular tumours have the ability to establish a blood supply for themselves by secreting a humoral factor which s t i m u l a t e s the i r hos t ' s endo the l i a l ceils to proliferate and to migrate towards the tumour source. The mechanism of action of such a humoral anglogenesis factor is more than that of an endothelial-cell growth factor since it requires an oriented migration of c e l l s towards the tumour . We repor t here the activation of pure skin-fibroblast procollagenase by a l o w m o l e c u l a r w e i g h t angiogenesis factor capable of s t i m u l a t i n g endo the l i a l ce l l growth in vitro. The a c t i v a t i o n was observed when either Type I or III collagen was used as substrate. It is suggested that at least one function of angiogenesis factor is to promote l imi t ed degradation of the connective tissue through which it passes causing channeling in the matrix along which stimulated endothelial cells may migrate.