Influence of thyroid-stimulating hormone on 18F-fluorodeoxyglucose and 99mTc-methoxyisobutylisonitrile uptake in human poorly differentiated thyroid cancer cells in vitro.
OBJECTIVE
In poorly differentiated thyroid cancer originating from thyroid follicular cells, the ability to concentrate iodine is lost. This makes recurrence undetectable by (131)I whole-body scan. In this situation, other radiopharmaceuticals, such as (18)F-fluorodeoxyglucose ((18)F-FDG) and technetium-99m-methoxyisobutylisonitrile ((99m)Tc-MIBI), are used to evaluate recurrence or metastasis. Some reports suggest that (18)F-FDG uptake is increased by thyroid-stimulating hormone (TSH) stimulation. This study aimed to determine the influence of TSH on (18)F-FDG and (99m)Tc-MIBI uptake in human poorly differentiated thyroid cancer cells in vitro.


METHODS
The cells were stimulated with 1000 muU/ml of recombinant human thyroid-stimulating hormone (rhTSH) for 1 day, 3 days, and 5 days. Each cell was incubated with 0.5 MBq/ml-1 MBq/ml of (18)F-FDG or 0.5 MBq/ml-1 MBq/ml of (99m)Tc-MIBI for 1 h at 37 degrees C. The uptake of each radiopharmaceutical in the cells was quantified as a percent of whole radioactivity per total viable cell number. The quantification of glucose transporter 1, 2, 3 and 4 mRNA expression was measured using RT-PCR.


RESULTS
TSH stimulation increased (18)F-FDG uptake in a time-dependent manner. Following 5 days of rhTSH stimulation, (18)F-FDG uptake was approximately 2.2 times that of the control. The increase in (18)F-FDG uptake following rhTSH stimulation was correlated to the increase in GLUT4 mRNA level. The GLUT1 mRNA level was unchanged. An increased uptake of (99m)Tc-MIBI was observed with a pattern similar to that of (18)F-FDG. The (99m)Tc-MIBI uptake was approximately 1.5 times that of the control 5 days later.


CONCLUSIONS
These results suggest that TSH stimulates (18)F-FDG and (99m)Tc-MIBI uptake in poorly differentiated papillary thyroid cancer, and therefore (18)F-FDG-PET or (99m)Tc-MIBI scans under TSH stimulation may be more accurate than under suppression.
Kim
Chung Ho
CH
Department of Radiology, College of Medicine, The Catholic University of Korea, Kangnam St. Mary's Hospital, 505 Banpodong, Seocho-Gu, Seoul 137-701, South Korea.
Yoo
Ie Ryung
IeR
Chung
Yong An
YA
Park
Young Ha
YH
Kim
Sung Hoon
SH
Sohn
Hyung Sun
HS
Chung
Soo Kyo
SK
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D002454:Cell Differentiation; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006801:Humans; D008657:Metabolic Clearance Rate / Q000187:drug effects; D011877:Radionuclide Imaging; D017256:Technetium Tc 99m Sestamibi / Q000493:pharmacokinetics*; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D013972:Thyrotropin / Q000008:administration & dosage*; D014407:Tumor Cells, Cultured
D019788:Fluorodeoxyglucose F18; D013972:Thyrotropin; D017256:Technetium Tc 99m Sestamibi