CHARACTERIZATION OF A SMALL-CELL-LUNG-CARCINOMA CELL-LINE FROM A PATIENT WITH CANCER-ASSOCIATED RETINOPATHY

We examined the biologic properties of a small-cell-lung-carcinoma (SC LC) cell line (designated MN-1112) established from a patient with SCL C who showed paraneoplastic retinopathy syndrome. Morphologic and immu nocytochemical analyses showed that MN-1112 cells possess features of the classic type of SCLC. MN-1112 cells grew in suspension forming rel atively large clumps of cells with a doubling time of 72 hr. By light- microscope examination, the cells were relatively small and had scanty cytoplasm. The cells produced NSE, ACTH and CK (BE isozyme); they als o expressed recoverin, a novel photoreceptor protein, detected by Nort hern-blot and Western-immunoblot analysis using human-recoverin-specif ic DNA probe and anti-bovine-recoverin polyclonal antibody. This repor t shows that human recoverin is expressed in cultured SCLC cells. Our results support the hypothesis that, in cancer-associated retinopathy (CAR) patients, auto-immune antibody targeting for ectopic recoverin i n SCLC is initially produced and cross-reacts with the retinal protein , resulting in the retinal degeneration that occurs in CAR patients. ( C) 1996 Wiley-Liss, Inc.