Tumoricidal cytokines enhance radioiodine uptake in cultured thyroid cancer cells.

Abstract

We explored whether the stimulation of iodine uptake by interferons seen in rat thyroid cell line is reproducible in human thyroid cancer and thus applicable to enhance the efficacy of radioiodine therapy. Surgical specimens from 12 papillary and 2 follicular adenocarcinomas were minced and seeded in culture trays. After 14-16 days in a medium supplemented with 5% calf serum, we measured cellular uptake of 125I during a 40-min incubation period. In 8 of 12 papillary and all 2 follicular carcinomas, interferon-gamma significantly stimulated iodine incorporation. The four nonresponder tumors had lower basal iodine uptake and relatively less differentiation of histologic features. The effect was dose dependent (0-100 U/ml), and the average maximum increase in responding cases was 35.1% over basal values. Tumor necrosis factor-alpha alone did not alter uptake, but at 300 U/ml it further enhanced the effect of interferon-gamma in the two follicular tumors. In addition to the pure cytokines, supernatant from lymphocyte culture conditioned with a bacterial immunostimulator also boosted radioiodine trapping in thyroid cancer cells. These in vitro results warrant animal experiments to test potential usefulness of tumoricidal cytokines in radioiodine therapy.