Bone resorption in osteogenic sarcoma--II. Resorption of the bone collagenous matrix by tumor cells, normal fibroblasts and macrophages.

Three osteogenic sarcoma cell lines of human and canine origin were compared to normal fibroblastic cells and peptone-induced murine peritoneal macrophages in terms of bone collagenous matrix (BCM) resorption capacity. The dissolution of the BCM was measured in an in vitro system consisting of the tested cells and live or killed [3H]-proline-labeled fetal mouse long bones. Experiments with osteogenic sarcoma cells revealed a paradoxical phenomenon indicating an inverse relationship between the number of tumor cells and the rate of collagen resorption from live bones. On the other hand, collagen matrix of devitalized bones, particularly those denatured by exposure to heat, is strongly resorbed by osteogenic sarcoma cells even in the presence of serum. Contrary to osteogenic sarcoma cells, normal fibroblasts do not resorb collagen from either live or killed bones, regardless of the devitalization method and culture conditions utilized. Macrophages resorb collagenous matrix from live bones, but their collagen resorption activity from devitalized bones depends greatly on choice of the incubation condition. Results have shown that osteogenic sarcoma tumor cells, when acting alone, may not have the capacity to destroy healthy bone. We suggest, therefore, that bone destruction seen in osteogenic sarcoma patients depends on the metabolic condition of the affected bone, and the interaction between the tumor and normal host cells and tissues.