A Pulmonary Large Cell Carcinoma Cell Line Expressing Neuroendocrine Cell Markers and Human Chorionic Gonadotropin α‐Subunit

A cell line producing the neuroendocrine cell surface antigen and human chorionic gonadotropin (hCG) α‐subunit, designated as KTA7, was established from human large cell carcinoma using a serum‐free medium, ACL‐3. KTA7 continued to grow in the ACL‐3 medium, showing the morphological characteristics of large cell undifferentiated carcinoma. The KTA7 cells reacted with antibodies such as 6H7 and MOC1 directed against the cell surface antigens and PGF9.5 directed against a cytoplasmic protein of neuroendocrine cells but did not possess either most epithelial markers other than low‐molecular‐weight keratin (Cytokeratin) or neuron‐specific enolase. The KTA7 cells, by immunostaining with anti‐hCG subunit antibodies, were shown to produce hCG α‐ but not β‐subunit, Northern blot analysis showed KTA7 RNA to synthesize hCG α‐subunit mRNA but not that of the hCG β‐subunit. Thus, the hCG α‐subunit alone was independently expressed in KTA7. Chromosome analysis showed loss of alleles of chromosome 3p and 17 in KTA7 cells but not loss of 13q. KTA7 was considered to be derived from large cell undifferentiated carcinoma with neuroendocrine differentiation (large cell neuroendocrine tumor) and thus may fine use in studies on the pathobiology of large cell‐type neuroendocrine tumors since it expresses at the same time marker substances of neuroendocrine differentiation and the hCG α‐subunit.