Culture of primary lung tumors using medium conditioned by a lung carcinoma cell line

Medium conditioned by the established lung tumor cell line A549 was used as a supplement to culture cells from primary solid lung tumors. Of 36 cases placed into culture, primary cells were obtained in 33 (91.7%). Of 29 cases in which subcultures were attempted, 18 (62.1%) were successful. Nine cell lines have been established by this technique to date. In growth assays, conditioned medium (CM) was found to stimulate both monolayer colony formation and growth in semi‐solid medium of cells cultured from primary solid tumors. CM has been found to contain factors with the properties of both transforming growth factorα (TGFα) and insulin‐like growth factor‐I (IGF‐I). The addition of a combination of these factors as purified peptides to basal medium at levels found in CM (0.1–0.5 ng/ml) stimulated colony formation of lung tumor cells by up to fourfold. These results indicate that secretion of growth factors may be important in tumor growth in vivo, and that use of CM may be a valuable tool for obtaining cultures from primary solid tumors.