USF-1, USF-2, PTEN 및 갑상선 전사인자들이 갑상선 세포의 기능과 증식에 미치는 영향

Abstract

Background: Upstream stimulatory factors(USFs) and PTEN are known to be tumor suppressants. USFs and PAX-8 were reported to be the functional competitors in sodium iodide symporter(NIS) gene expression. We investigated the effects of USF-1, USF-2, PTEN, and thyroid-specific transcription factors(TTF-1, PAX-8) on the function and growth of thyrocytes of FRTL 5 rat thyroid cells. Methods: Complementary DNAs of the USF-1, USF-2, PTEN, TTF-1(homeodomain), and PAX-8 were synthesized from RNA extracted from FRTL-5using an RT-PCR kit. Each of them was transiently transfected to the FRTL-5 cells using the lipofectamine after being cloned into the pcDNA3.1 vectors. Stable cell lines, which were transfected by USF-1, PTEN, TTF-1, and PAX-8, were also obtained from the FRTL-5 cells, respectively. Extracellular cAMP concentrations were measured after 24 hours of incubation with varying concentrations of bTSH(0.1～100mIU/mL). After, [Methyl-3H] thymidine uptake or 5-bromo-2'-deoxyuridine(BrdU) assay was performed.Results: USF-1 and USF-2 significantly increased cAMP levels and decreased thymidine uptake in both transiently and stably transfected cells(p<0.01). PTEN had a tendency to increase both the cAMP levels and BrdU uptake in stable cells, but had a tendency to decrease thymidine uptake intransiently transfected cells. TTF-1 significantly increased the cAMP levels and either thymidine or BrdU uptake in both transiently and stably transfected cells(p<0.05). PAX-8 significantly increased both the cAMP levels and BrdU assay in stable cells, but in transiently transfected cells, it significantly decreased cAMP concentrations(p<0.01). Conclusions: These results suggested that both the USF-1 and USF-2 play a role in suppressing the growth of thyrocytes but at the same time, they kept the ability to produce cAMP after TSH stimulation. They had opposing effects on TTF-1 and PAX-8 in terms of the proliferation of thyrocytes