Establishment of a prostatic small-cell carcinoma cell line (SO-MI)

BACKGROUND: Prostatic small-cell carcinoma is an extremely rare, highly aggressive disease. We established a cell line from this tumor. MATERIALS AND METHODS: Tumor tissue obtained from a 24-year-old Japanese man was used to establish the cell line. Cultured cells and tumors transplanted into nude mice were characterized by histologic, immunohistologic, immunocytologic, and molecular biologic methods. RESULTS: An immortal culture cell line (SO-MI) was successfully established. SO-MI cells adhered weakly to plastic surfaces in vitro, showing a 52- to 72-hr doubling time. SO-MI cells were heterotopically and orthotopically transplantable in nude mice. The cells were immunoreactive for NSE, chromogranin A, and NCAM, but not for ACTH, calcitonin, serotonin, gastrin, insulin, glucagons, LCA, EMA, PAP, PSA, androgen receptor, and p53. SO-MI cells secreted NSE in vitro and in vivo. SO-MI cells at passage 30 contained 50-59 chromosomes with a modal number of 55. PCR suggested that the p53 gene was deleted in SO-MI cells. RT-PCR detected no mRNA encoding androgen receptor in these cells. CONCLUSIONS: SO-MI cells retain the neuroendocrine nature of the original tumor, and should be useful in studying possible etiologies and new treatments.