Semenogelins are ectopically expressed in small cell lung carcinoma

Two proteins recovered from cell surface adhesion complexes in a small cell lung carcinoma (SCLC) cell line were identified as fragments of the semina l plasma proteins semenogelin I and semenogelin II. Association of both pro teins with the adhesion complexes was induced by epidermal growth factor. E xpression of semenogelins was previously thought to be highly specific to s eminal vesicles, but Western blot analysis demonstrated that semenogelin II is widely expressed in SCLC cell lines and occasionally in other malignant cell lines. Although semenogelin expression is normally restricted to male s, two SCLC cell lines from female patients were also positive for semenoge lin ZI expression. Immunohistochemical analysis demonstrated diffuse expres sion of semenogelins in 12 of 13 SCLC tumors and focal expression in a mino rity of lung squamous and adenocarcinomas, Semenogelins were secreted into the medium by cultured SCLC cells, which suggested that these proteins mag. be useful markers for detecting residual tumor burden or recurrence of SCL C after treatment.