Calcitonin as an Indicator of the Response of Human Small Cell Carcinoma of the Lung Cells to Drugs and Radiation1

A calcitonin (CT)-producing cell line (DMS53) established from human small cell carcinoma of the lung was grown as threedimensional multicellular spheroids in spinner culture or on agar in multiwells, and as tumors in nude (athymic) mice. CT release into the media was directly proportional to spheroid volume. The response of these cells following exposures to X-irradiation, Adriamycin, or diazoacetylcholine iodide was assessed by mon itoring levels of CT released into the media by individual sphe roids. Levels of CT in the blood of nude mice bearing DMS53 xenografts were directly proportional to tumor volume and de creased proportionally with tumor response to X-irradiation and cisplatin treatment. These results suggest that the DMS53 sphe roid and xenograft models may be useful systems to monitor responses to therapy utilizing CT as an indicator of tumor burden.