Modes of Growth and Spread of a Transplantable, Virus-Producing Murine (Moloney) Sarcoma: Karyotypic Analyses2

Abstract

Cloned cells of a virus-producing, transplantable murine (Moloney) sarcoma line (MSC) contained a set of stable, structurally rearranged, “marker” chromosomes. These identifying markers were not present in cells newly transformed by murine sarcoma virus (MSV). It was therefore possible, after MSC cell injection, to determine whether or not any causal relationship existed between MSV produced in vivo and subsequently developing primary and secondary neoplasms. Each adult and neonatal mouse given 10⁶ MSC cells developed a progressing primary sarcoma. Many exhibited secondary pulmonary neoplasms as well, and some neonates developed secondary tumors in their spleens and periosteal tissues. Of 879 metaphase spreads prepared from primary and pulmonary neoplasms, all contained MSC marker chromosomes. In contrast, cells explanted from a periosteal tumor of a neonatal mouse uniformly lacked such markers, even though the primary sarcoma of the same mouse consisted of MSC cells exclusively. Similarly, none of 180 metaphase spreads obtained from sarcoma virusinduced primary tumors contained MSC marker chromosomes. Primary sarcomas and secondary pulmonary neoplasms-the lesions most frequently encountered in this system-developed, respectively, by replication and metastasis of MSC cells. Virus recruitment of new tumor cells appeared to have only a minor role associated with the spread of sarcomas in neonatal mice.