Establishment and characterization of a human lung adenocarcinoma cell line (LC‐2/ad) producing α1‐antitrypsin in vitro

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Abstract
A new human cell line, LC-2/ad was established from pleural effusion of pulmonary adenocarcinoma of a 51 year old Japanese female. The LC-2/ad cells exhibit an epithelial appearance and a tendency to form small domes as observed with phase-contrast microscopy. The modal chromosome number was 53-56. Plating efficiency and doubling time were 6.8% and 58 h, respectively (32th passage). Immunocytochemically, the cells were strongly positive for CEA and cytokeratins including cytokeratin no. 18 which is present in simple epithelia. Ultrastructurally, the cultured cells were characterized by well-formed junctional complexes and microvilli. Subcutaneous injection of 5 x 10(6) cells into a nude mouse resulted in tumor formation classified histologically as a moderately differentiated adenocarcinoma. This cell line produced at least two functionally active trypsin inhibitors together with several proteinases in vitro. The main inhibitor was purified partially from the serum-free conditioned medium and confirmed immunologically as human alpha 1-antitrypsin (AAT). Immunohistochemically, the xenografted tumor was also positive for AAT. The cell line LC-2/ad is useful for the study of tumor-derived serine proteinase inhibitors, in particular AAT.