Cell surface properties of spontaneously metastasizing rat mammary adenocarcinoma cell clones

Rat 13762NF mammary adenocarcinoma mimics human breast cancer in its pathology and pathogenesis. We selected and cloned spontaneously metastasizing variant tumor cell lines that spread from mammary fat pad subcutaneous sites to regional lymph nodes and lung. The biologic properties of these tumor clones changed during propagation in vitro. Examination of cell surface properties of the tumor clones indicated that the quantitative display of particular cell surface glycoproteins correlated with metastatic potential. One of these was a sialogalactoprotein (gp580), which bound 125I-PNA after desialyzation and was expressed in increased amounts on the more metastatic clones. Another was a major sialoglycoprotein (gp80) that was identified by chemical labeling of cell surface sialic acid residues and showed decreased amounts on the more metastatic clones. Comparison of the rat mammary tumor glycoproteins with similar components on metastatic human carcinoma cells indicated close similarities in the WGA-binding glycoproteins expressed on metastatic cells derived from metastases.