Objective To establish a recombinant plasmid expressing hNIS gene regulated by promoter Egr-1 and then transfected to human cervical cancer cell lines Hela, to evaluate the radiation-induced Egr-1 promoter of hNIS protein function. Methods Egr-1 promoter sequence was amplified by PCR from the template Egr-1/pMR18T and was sub-cloned into the vector FL * -hNIS/pcDNA3, to construct the recombinant plasmid Egr-1 -hNIS/pcDNA3, and then verified by restriction enzyme electropho-resis. The recombinant plasmid was used to transfect human cervical cancer Hela cell line with FuGENE HD. Single clone named Hela-Egr-1-hNIS was obtained by G418 screen and expanded in selection media. The expression of NIS gene was detected by flow cytometry (FCM) and RT-PCR, respectively. A 125 I dynamic uptake experiment using different doses of X-ray ionizing radiation was performed to evaluate the iodide uptake of Hela-Egr-1 -hNIS and Hela-NIS ( + ) cells, which was obtained from the previous study. The untransfected Hela cells were used as the control. Results The recombinant plasmid Egr-1- hNIS/pcDNA3 was established successfully and the cell lines stably expressing NIS gene were obtained after transfecting into Hela cells. The highest level of expression efficiency of NIS was 11. 2% with FCM, and the expression of NIS gene was proved by RT-PCR from Hela-Egr-1-hNIS cells. 125I dynamic uptake experiments showed that the iodine uptake capacity of Hela-Egr-1-hNIS cells was increased by 13 folds than the negative control. After X-ray ionizing radiation, the iodine uptake rate of Hela-Egr-1-hNIS cells was increased and have a positive correlation with the radiation dose from zero to six Gy( r =0. 960,P = 0.04) , while the uptake rate of Hela-NIS( + ) was decreased and had no correlation with the dose of X-ray( r= -0. 770,P >0. 05). Conclusion The Hela-Egr-1-hNIS cell lines stably expressing the Egr-1 promoter-driven hNIS protein were established successfully, showing a strong capability of iodide uptake and a certain effect of radiation inducement, and may achieve a better therapeutic effect in vivo.
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