Metastatic growth of v-fos-induced osteosarcoma, following in vitro cultivation

A tumour cell line was established from a non-metastatic osteosarcoma which had developed in the right femur after infection of a newborn mouse with FBR osteosarcoma virus (FBR MSV). After 20 cell culture passages and injection of the cells into newborn syngeneic mice, the animals developed fibrosarcomas on the site of injection. Metastatic lung tumours were detected in 50% of the mice. Metastatic tumour growth was preferentially observed in the walls of large blood vessels and in subpleural zones. Large areas of the metastatic tumours resembled mature connective tissue. This model of in vitro progression from a primary non-metastasizing osteosarcoma to a neoplasm with particular metastatic potency, though with a growth pattern similar to fibromatosis may serve as a useful system to study the different steps of metastatic progression, distinct tropism of invasive cells and fibrous maturation of metastatic tumours.