Characterization of Gelatin‐Degrading Metalloproteinase Activities of the Dunning Rat Prostate Tumor Grown in Nude Mice

Proteinase activities in the Dunning R‐3327 prostatic tumor grown in nude mice and the dorsal lobe of the normal Copenhagen rat prostate were characterized using gelatin‐containing SDS‐polyacrylamide gel electrophoresis. Calcium‐stimulated activities of approximately 33, 42, 64, 71, 76, 85, 98, 115, and 120 Kd as well as a 91 Kd calcium‐independent proteinase were detected in the tumor, whereas the dorsal prostate showed calcium‐dependent activities of approximately 62 and 80 Kd and a calcium‐independent activity >120 Kd. The zymographic calcium‐dependent proteinase patterns in the other rat prostatic lobes (a 62 Kd proteinase in the anterior lobe; 59, 62, and 67 Kd forms in the ventral lobe; and 52, 62, and 72 Kd activities in the lateral lobe) were distinctive from that of the tumor and of the dorsal lobe. The calcium‐dependent and ‐independent proteinases of the tumor were active over a broad range of pH values with optimal activity near pH 8.0–8.4. The calcium‐dependent activities were inhibited by EDTA and EGTA. Barium and strontium could partially substitute for calcium. The calcium‐independent activities were not affected by these chelators nor by the proteinase inhibitors benzamidine, ϵ‐aminocaproic acid, tranexamic acid, hydrocinnamic acid, or iodoacetate. Similarly, the metalloproteinase activities were not affected by the latter inhibitors. There was little change in the predominant molecular forms (64, 71, and 76 Kd) of proteinase following castration of tumor‐bearing nude mice; however, the 98 Kd calcium‐dependent activity decreased and the 91 Kd calcium‐independent activity increased as a result of this treatment.