Endothelium growth suppressing and
tumor-regressing activities were copurified from the
conditioned medium of P388D1 culture in the presence of 100 microg/ml carboxymethylated
curdlan by a procedure including
ammonium sulfate fractionation and six column chromatographies of Ceramic
hydroxyapatite, Q-
Sepharose, Sephacryl S-300 HR, Matrex PBA-30, PBE94, and anti-
bovine serum albumin (anti-BSA)
agarose. The
intravenous administration of the purified growth suppressing factor for endothelial cells to
sarcoma 180-bearing mouse caused a rapid decrease in the number of viable
tumor cells in
tumor lumps within 16 h. Immunohistochemical study showed that the
intravenous injection of the purified factor to
sarcoma 180-bearing mouse resulted in
hemorrhagic disorder all over the tissue in the
tumor lamp. Thus, the purified factor exhibited not only growth suppressing activity for endothelial cells but also
tumor regressing activity at a concentration as low as about 15 ng/mouse. The purified factor significantly inhibited in vitro tubulogenesis of bovine artery, human umbilical vein, and adult human darmal microvascular endothelial cells on
collagen gel at a concentration of about 5 ng/ml. After the tube formation of endothelial cells was completed on a
collagen gel, the purified factor disrupted the tubes at a concentration of about 5 ng/ml within 48 h. These findings demonstrate that endothelium growth suppressing factor is a potent inhibitor of angiogenesis as well as the growth of endothelial cells, and may bring about the regression of a solid
tumor by inhibiting angiogenesis.