RT Journal Article
SR Electronic
T1 Monitoring radioiodine-induced apoptotic and autophagic cell death in mouse colon cancer model
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 1447
OP 1447
VO 57
IS supplement 2
A1 Kyung Oh Jung
A1 Hyewon Youn
A1 Seock-Jin Chung
A1 Keon Wook Kang
A1 June-Key Chung
YR 2016
UL http://jnm.snmjournals.org/content/57/supplement_2/1447.abstract
AB 1447Objectives Colorectal cancer (CRC) is one of the most prevalent cancers worldwide. There are many researches about cell death in colorectal cancer after chemotherapy and radiotherapy. However, cell death for internal radiation was not clarified. Because cell death induced by therapy is different according to colon cancer cell lines, evaluation of cell death such autophagy and apoptosis is important for more effective therapeutic strategies. Here, we confirmed apoptotic and autophagic cell death after radiotherapy in different colon cancers.Methods The HCT116 and HT29, human colorectal carcinoma cells, were transfected with NIS specific reporter (pCMV-NIS) which could uptake radioiodine. The NIS expression and 125I uptake were estimated in the transfected cells. After 131I therapy, the level of apoptosis and autophagy was confirmed by caspase 3 and LC3 antibody in western blot. For autophagic cell death in HT29 cells, HT29 cells were transfected with LC3 specific reporter (pCMV-LC3-GFP) which was designed to show LC3 located in autophagosome. TEM images and confocal microscopy were performed to visualize autophagic cells death. In tumor xenograft models, activation of caspase 3 was imaged by bioluminescence imaging for vivoglo and immouhistochemistry in ex-vivo tissues was performed for detecting caspase 3 and LC3.Results The HCT116 and HT29 cells, transfected with pCMV-NIS, showed higher I uptake and NIS expression than control cells. In HCT116 cells, expression of caspase 3 was increased in NIS expressing cells after 131I therapy. Whereas expression of caspase 3 in NIS expressing HT29 cells was not increased, LC3 was highly expressed after 131I therapy. In TEM images, HT29 cells with NIS expression also showed morphologic change such as autophagosome and autolysosome after 131I therapy. In confocal microscopy, NIS expressing HT29 cells, transfected with pCMV-LC3-GFP, has more green fluorescence dots than non-expressing HT29 cells after 131I therapy, indicating the presence of LC-3 proteins bound autophagosome. In xenografts, vivoglo images showed that there were no differences of caspase 3 activity between NIS expressing and non-expressing HT29 cells after 131I therapy. In ex-vivo tissues, whereas there was no difference of caspase 3 expressions, there were more green fluorescence dots and expression of LC3 in NIS expressing HT29.Conclusions Apoptotic and autophagic cell death induced by radioiodine therapy were successfully visualized in different colon cancer cells. These evaluation of cell death such autophagy and apoptosis could be useful information for more effective therapeutic strategies.