Metastasis is dependent on both host and tumor cell characteristics (1-3). In order to study tumor cell properties associated with metastasis, a number of animal tumor models have been developed by sequential selection methods in vivo (4-9) and in vitro (10-13). Of particular interest are cell surface properties of these tumor models because in several systems the cell surface appears to be important in determining the degree and location of experimental metastasis (3,6,(12)(13)(14)(15)(16).A tumor model for lymphosarcoma metastasis has been developed from the murine RAW117 lymphosarcoma line which is capable of forming some solid tumor nodules in livers, lungs, and spleen of syngeneic BALB/c mice (5). By selecting 10 times for liver colonization, a more malignant lymphosarcoma subline RAW117-HlO was obtained which rapidly killed its host (5) and formed t200-250 times more gross liver tumor nodules than did the parental line RAW117-P after intravenous injection (5, 13). Utilizing the low-malignancy RAW117-P parental line, we selected in vitro for nonadherence to immobilized lectins such as concanavalin A (Con A) to obtain variant sublines that show increased potential for experimental metastasis in vivo (13,17). Similarly, selecting in vitro of the highly malignant subline RAW117-H1O on wheat germ agglutinin (WGA) yielded variant sublines with decreased metastatic potential (13). The cell surface properties of these lymphosarcoma sublines and several clones derived from them have been analyzed, and we find that there is an inverse relationship between the metastatic potentials of these sublines and clones and the expression of cell surface RNA tumor virus envelope glycoprotein gp7O. MATERIALS AND METHODSCell Lines. RAW117 lymphosarcoma cells were grown as described (5). The methods of sequential in vivo selection for malignant variant sublines (RAW117H1 through RAW117-H10) with enhanced ability to form solid tumor colonies in the livers of syngeneic BALB/c mice (5) and the methods for repeated in vitro selections for lectin-binding variant sublines (RAW117-P Con Aa10 and RAW117-H10 WGAal1) on lectincoated petri dishes have been reported (13,17).Cell Clones. Clones were obtained from the established parental cell line RAW117-P, from the in vivo-selected subline RAW117-H10, and from the in vitro-selected sublines RAW117-P Con Aa10 and RAW117-H10 WGAal1 by the limiting-dilution technique. Briefly, cells were diluted to one cell per ml in Dulbecco's modified Eagle's medium (GIBCO) containing 10% heat-inactivated (560C, 30 min) fetal bovine serum (Flow Laboratories, Inglewood, CA), and 0.2 ml was distributed to each of 96 wells in a Microtest II plate (Falcon). After 2 weeks, clones were visible as a small white spot on the bottom of the well; infrequent wells with two clones were discarded. Cloning efficiencies of the RAW117 lines and sublines were approximately 80%In Vivo Assays. RAW1 17 lines were assayed for organ colonization (experimental metastasis) after intravenous injection of 5000 viable lymphosarc...