| Objective:To research the difference of the radionuclide uptake of lung cancer cells A549/DDP mediated by the human sodium/iodide symporter (hNIS) gene and the rat sodium/iodide symporter (rNIS) gene, and to investigate the feasibility of radionuclide imaging and assess the therapy effect of A549/DDP cells and A549/DDP xenografts after doses of131I treatment mediated by NIS gene.Methods:Ad-eGFP-hNIS and Ad-eGFP-rNIS were transfected into A549/DDP respectively. The toxicity and the transfected efficiency were detected by MTT and flow cytometry respectively. The gene expression for hNIS and rNIS were examinated by reverse transctrption-polymerase chain reaction (RT-PCR). The function of the two genes was evaluated with radioactive technetium (99mTc) and radioactive iodine (131I) dynamic uptake experiments. Xenografted A549/DDP model were established in nude mice. Radioactive isotope99mTc imaging was peformed using SPECT and the radioactivity of the xenografted tumors and other organs of the mice were counted using gamma counter after tail vein injection.Apoptosis of the cells after treatment with131I in vitro were detected by Annexin V-FIFC/PI double-labled flow cytometry and Hochest33258fluorescence staining. When the xenograft tumor models were established, the tumors of the mice were injected with Ad-eGFP-rNIS in rNIS group, or PBS in the control group respectively. After intraperitoneal injection of31I, tumor growth of every mouse was monitored and immun ohistochemical staining was conducted to detect the apoptosis cell.Results:When MOI≤3000, the transfected cell viability was virtually unaffected as determined by MTT colorimetric assay (P=0.153; P=0.081). The eGFP-positive cells were visualized under the microscope after transfected by Ad-eGFP-hNIS and Ad-eGFP-rNIS. The transfected efficiency were89%and91%respectively when MOI was800. The levels of hNIS gene and rNIS gene expression in transfected cells were higher than those in untransfected cells. And the uptake value of99n’Tc in transfected cells with hNIS or rNIS were14times or18times higher than that in the non-transfected cells respectively, while131I was12times or16times higher than that in the non-transfected cells respectively. And the uptake of the transfected cells were both inhibited by KClO4, but the radionuclide was effluenced quickly from the tumor cells, the elimination half-time was not more than five minutes. After the A549/DDP xenograft nude mice model were successfully established,99mTcO4-imaging showed that the tumor of transfected group accumulated99mTcO4-. whereas no99mTcO4-uptake was found in control group. And the biodistribution in tumor-bearing mude mice model showed that the uptake capacity of99mTcO4-of tumor in hNIS and rNIS group was8.7and10.3times higher than the control group. After the cells intervened by doses of131I, the percentage of apoptosis cells transfected with hNIS and rNIS gene were35%and65%respectively, which were higher than that of the cells without transfection (hNIS:P=0.031; rNIS:P=0.008). And the apoptosis rates of the cells transfected with rNIS was higher than the hNIS (P=0.01). Compared with the untransfected cells, many nuclear cracked and shrinked cells were detected in transfected NIS cells by Hochest33258staining. When the xenogrfts were injected into I31I, the tumors of control group grew quickly, whereas the tumor’s growth was slow in the transfected group. The apoptosis cells were detected in the rNIS group, but those were not dectected in the control group.Conclusion:A549/DDP cells can uptake99mTc and131I effectively mediated by hNIS and rNIS gene, and can also be killed by131I. We can see NIS genge transfer combined with99mTcO4-scintigraphy and radioiodine therapy open the new way for the diagnosis and treatment of the nonthvroid tumors. |
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