ANTITUMOR SUBSTANCES IN CARTILAGINOUS TISSUE

Anti-tumor substances were extracted from fetal bovine costal cartilag e with I M guanidine hydrochloride (GuHCl) and partially purified by u ltrafiltration through Amicon XM-300, YM-100 and YM-30 membranes, yiel ding four different molecular weight fractions (30 kD >, 30-100 kD, 10 0-300 kD, 300 kD <). Their anti-tumor activity was then assessed mainl y by in vivo assay with B16 melanoma cells inoculated into BDF1 mice. Inhibitory activity against tumor angiogenesis was determined by using chick embryo chorioallantoic membranes (CAMs) and inhibitory activity against production of plasminogen activators (PAs) by B16 melanoma ce lls was assayed by the microplate immunocapture assay in vitro, The 30 kD > fraction showed little inhibitory activity against either tumor growth or tumor metastasis, but displayed strong anti-angiogenic activ ity on CAMs, The 30 kD> fraction, however, did not exhibit any inhibit ory activity against PA production. In contrast, the 30-100 kD fractio n contained strong inhibitory activity against PA production as well, in particular urokinase-type PA (uPA) production and showed the strong est inhibitory activity against tumor growth and tumor metastasis of a ll fractions, but little anti-angiogenic activity on CAMs. The other f ractions did not show any inhibitory activity against tumor growth, tu mor metastasis, or PA production. These findings suggest that the 30-1 00 kD fraction contains a cartilage-derived plasminogen activator inhi bitor (CD-PAI) that appears to be the main anti-tumor substance in car tilaginous tissue and to play an important role in the anti-turner mec hanism of cartilaginous tissue.