title: Comparison of Cerenkov luminescence imaging (CLI) and gamma camera imaging for visualization of let-7 expression in lung adenocarcinoma A549 Cells.
abstract: OBJECTIVE
  miRNA is an important factor for tumorigenesis which could act as a potential molecular target for tumor diagnosis. The goal of this study was to explore a new method for visualizing the expression of let-7 in lung adenocarcinoma A549 cells by Cerenkov luminescence imaging (CLI) and gamma camera imaging.
  
  
  METHODS
  The human sodium/iodine symporter (hNIS) and 3'-UTR sequence of the ras gene (RU) that complementarily binds to let-7 were cloned with hNIS serving as the reporter gene. The expression of hNIS regulated by let-7 in the fusion gene hNIS-RU was constructed; the let-7 primer (pri-let-7), which could specifically bind to RU and the mir-143 primer (pri-mir143) not binding with RU, was cloned. A549 cells were transfected with hNIS or hNIS-RU, and additional cells were cotransfected with hNIS-RU and different concentrations of pri-let-7 or pri-mir143. The cells were incubated with 740kBq (131)I-containing media for 1h, 24h after transfection. CLI, gamma camera imaging, and γ counting were subsequently conducted, and the correlation among CLI, gamma camera imaging, and γ counting was compared when cotransfected with pri-let-7.
  
  
  RESULTS
  CLI, gamma camera imaging, and radioactive counting showed that hNIS-transfected A549 cells had significantly higher uptake of (131)I compared to non-transfected cells. The uptake of (131)I in hNIS-RU transfected A549 cells decreased to approximately 70% compared to hNIS-transfected cells, since hNIS-RU expression was suppressed by intracellular let-7. After cotransfection with hNIS-RU and various concentrations of pri-let-7, (131)I uptake gradually decreased with increasing pri-let-7, while (131)I uptake remained roughly unchanged in the presence of hNIS-RU cotransfected with different amounts of pri-mir143. CLI was highly correlated with gamma camera imaging (r(2)=0.9893) and radioactivity counting (0.9779).
  
  
  CONCLUSIONS
  Based upon miRNA-regulated reporter genes which mediate the uptake of the radionuclide, both CLI and gamma camera imaging can noninvasively detect miRNA expression in cells, which may provide a new way for the visualization of miRNA expression.
authors: Department of Nuclear Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an, Shaanxi, 710032, China.
authors: Weidong
authors: W
authors: Yang
authors: Weiwei
authors: W
authors: Qin
authors: Zhenhua
authors: Z
authors: Hu
authors: Yaoyu
authors: Y
authors: Suo
authors: Rong
authors: R
authors: Zhao
authors: Xiaowei
authors: X
authors: Ma
authors: Wenhui
authors: W
authors: Ma
authors: Tao
authors: T
authors: Wang
authors: Jimin
authors: J
authors: Liang
authors: Jie
authors: J
authors: Tian
authors: Jing
authors: J
authors: Wang
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D000818:Animals; D001692:Biological Transport; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter / Q000235:genetics; D011905:Genes, ras / Q000235:genetics; D006801:Humans; D007457:Iodine Radioisotopes / Q000378:metabolism; D008163:Luminescent Measurements / Q000379:methods*; D008175:Lung Neoplasms / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics*; D011877:Radionuclide Imaging / Q000379:methods*; D027981:Symporters / Q000235:genetics; D000099209:Sodium-Iodide Symporters
chemical_list: D007457:Iodine Radioisotopes; D035683:MicroRNAs; D027981:Symporters; D000099209:Sodium-Iodide Symporters; C487931:mirnlet7 microRNA, human