Response of primary human lung carcinomas to autocrine growth factors produced by a lung carcinoma cell line.

Medium conditioned for 48 to 72 h by A549-1 lung carcinoma cells was used to culture primary solid lung tumors on feeder layers of inactivated Swiss 3T3 cells. Of 22 cases placed into culture, primary cultures of carcinoma cells were obtained in 20. Subcultures were obtained in 18 cases, and cell lines were established in nine cases. The neoplastic origin of the cultured cells was demonstrated by several criteria: tumorigenicity in athymic mice; anchorage-independent growth; expression of altered lactate dehydrogenase isoenzyme profiles; and expression of the lung tumor marker pregnancy-specific glycoprotein 1. The epithelial nature of cultured carcinoma cells was demonstrated by expression of keratin. These characteristics were compared to normal epithelial cells established in culture from bronchial explants from the same donors as tumor tissue, or other donors. The growth-stimulating effect of conditioned medium toward primary or newly cultured tumor cells was quantitated by clonal assays in soft agar and in monolayer culture. Growth response in clonal assays of newly cultured carcinoma cells to the purified growth factors transforming growth factor alpha and insulin-like growth factor 1, two known components of medium conditioned by A549-1 cells, was also demonstrated.