Cloned murine non-malignant, spontaneously transformed and chemical tumour-derived cell lines related to the type 2 pneumocyte.

NAL1A is a murine type 2 pneumocyte-related cell line cultured from normal BALB/c adult mouse lung. In vitro spontaneous transformation of 3 out of 7 clones of NAL1A has led to the isolation and establishment in continuous cell culture of sibling-related non-neoplastic (NAL1A) and spontaneously arising neoplastic (NAL1As) cell strains. NAL1As cells exhibited a similar phenotype to cloned NUL1 cells cultured from urethane-induced mouse lung adenomas. All NAL1As and NUL1 clones grew vigorously in 0.3% agar and formed invasive, poorly differentiated carcinomas following subcutaneous inoculation into immunesuppressed mice. Several subcutaneous nodules metastasised preferentially to the lung. All spontaneous and chemically-derived malignant clones were less differentiated than the non-malignant clones as assessed by staining with a type 2 pneumocyte-specific polyclonal antiserum. The clones described in this report form a useful model in the study of spontaneous and chemically-induced neoplastic transformation in mouse epithelial lung cells.