125I iodine uptake in murine T lymphoma cell line depending on thyroid status. Preliminary studies.

STERLE H; BARREIRO ARCOS M; TESÁN F; SALGUEIRO M; BORRE M; BOCCIO J; CREMASCHI G; ZUBILLAGA M

Porto de Galinhas, Pernambuco

Congreso; XXIII Congreso de Asociación Latinoamericana de Sociedades de Biología y Medicina Nuclear (ALASBIMN BRASIL 2011); 2011

ALASBIMN

Objective To study de 125I-iodine uptake of a murine T lymphoma growing as solid tumor in singeneic mice under different thyroid status. Materials and methods The in vivo study was performed on CF57Bl/6 mice bearing a murine El-4 T lymphoma as solid inguinal tumor. Before subcutaneous injection of El-4 cells mice were submitted to different treatment schemes to make them hypothyroid (hT, 0.5 mg/ml propylthiouracil given in the drinking water for 18 days) or hyperthyroid (HT, 0.6 μg/g body weight of T4 every day for 30 days). The group with no treatment was used as control (C). The in vivo uptake of Na125I in mice was performed as follows: 5 µCi Na125I in 0.1 mL of 0.9% sterile saline were injected i.v. to all mice. Four hours later, mice were sacrificed; their blood was collected, and thyroid glands, spleen and tumor were dissected and counted in a calibrated gamma counter. Radioiodine uptake was expressed as percentage of injected dose (%ID). The in vitro uptake of Na125I by El-4 cells was measured as follows: cells (1 x 105 cell / mL) were grown in RPMI 1640 medium supplemented with 10% fetal bovine serum plus antibiotics and glutamine. After aspirating the culture medium, cells were washed and resuspended in 1 mL of medium. 125I uptake was initiated by adding 0.5 mL 10 M NaI and Na125I (0.1 Ci/mL, to have around 100,000 cpm per well). Incubations proceeded for 35, 60, 120 and 240 minutes at 37 ºC, and were finished by aspirating the radioactive medium and washing with 1 mL of ice-cold medium twice. To determine the amount of Na125I associated with the cells, 1 mL of ice-cold absolute ethanol was added to each well and incubated for 3 hours at 4ºC. The supernatants containing alcohol extracts were transferred into vials for gamma counting. Radioiodine uptake was expressed as percentage of administered dose. Results 125I-iodine uptake in thyroids was lower for both treated groups (hT: 0.163 %ID, HT: 4.102%ID) than C (5.842%ID). Spleen shows low 25I-iodine uptake for all the groups (0.014%ID for hT, 0.422 %ID for HT and 0.606%ID for C). Tumor uptake was 0.158 %ID for hT, 5.990%ID for HT and 10.687%ID for C meanwhile %ID in blood samples were of 0.5 for hT, 4.6 for HT and 10.6 for C. In vitro studies demonstrated no uptake by the cell line originally injected. Conclusion The 125I-iodine uptake of the murine T lymphoma growing as solid tumor in singeneic mice is altered by the thyroid status of the animals. The values in tumor uptake were comparable to that of blood samples, suggesting that tumor cells may alter their metabolism or a possible tumor angiogenesis. More studies are being carried out to confirm these results.