Biological and Biochemical Characterization of a Somatostatin-producing Human Carcinoma Established by Heterotransplantation

A somatostatin-producing human carcinoma cell line was established by heterotransplantation into athymic nude mice. The original material, which was derived from a colon tumor of a patient who had previously had bilateral ovarian tumors contained 66 ng extractable somatostatin/g tissue. Somatostatin-producing cells could be identified by immunohistochemistry within the first tumor transplants. Although initially the somatostatin concentration was low (14 ng/g) a progressive increase was observed with each successive transplantation so that after 10 passages it reached a level of 127 ng/g tissue. Analysis of tumor extracts by gel filtration and high-performance liquid chromatography indicated that somatostatin-14 was the only molecular form produced by the original and by the transplanted tumor after multiple passages. This result demonstrates that the tumor has the ability to constitutively express the prosomatostatin gene and to process the primary translation product to somatostatin-14.