[In vitro uptake and release of 201Tl and 99mTc-MIBI in HeLa cell]

201Tl is useful in the diagnosis of tumor malignancy determined by the grade of washout rate to the normal tissue especially in lung tumors and thyroid tumors. 99mTc-MIBI, a tracer of myocardial blood flow is also a tumor tracer. We determined whether the growth of the tumor cell is related to the uptake and release of the these tracers in cultured cells (HeLa cell). Cultured HeLa cells were incubated for 1 hr with 10 kBq of either tracer for the kinetic study of cellular uptake and additionally incubated for 90 min with cold medium for the kinetic study of cellular release. These cells cultured with various concentrations of actinomycin D (ACD) were used to examine the correlation between cellular growth and kinetics of these tracers. The uptake in the cell reached a plateau at about 60 min and the uptake at 60 min correlated with the number of the cells and was identified for specific accumulation in the cell. The uptake of 201Tl and 99mTc-MIBI at 60 min was 5.17% and 1.32% respectively of the given dose. The release for 90 min showed almost the same tendency for these tracers. The cellular release of 201Tl with the addition of ACD was increased in association with the concentration of ACD. On the other hand, the cellular release of 99mTc-MIBI showed no change by the addition of ACD. In conclusion, 201Tl showed slower washout in high growth cells than in low growth cells, and could act as an indicator of tumor malignancy by assessment of its washout by the tumor.