Efficient multicistronic co-expression of hNIS and hTPO in prostate cancer cells for nonthyroidal tumor radioiodine therapy.

Radioiodine therapy has proven to be a safe and effective approach in the treatment of differentiated thyroid cancer. Similar treatment strategies have been exploited in nonthyroidal malignancies by transfecting hNIS gene into tumor cells or xenografts. However, rapid radioiodine efflux is often observed after radioiodine uptake, limiting the overall antitumor effects. In this study, we aimed at constructing multicistronic co-expression of hNIS and hTPO genes in tumor cells to enhance the radioiodine uptake and prolong the radioiodine retention. Driven by the cytomegalovirus promoter, hNIS and hTPO were simultaneously inserted into the expression cassette of adenoviral vector. An Ad5 viral vector (Ad-CMV-hTPO-T2A-hNIS) was assembled as a gene therapy vehicle by Gateway technology and 2A method. The co-expression of hNIS and hTPO genes was confirmed by a double-label immunofluorescence assay. The radioiodine ((125)I) uptake and efflux effects induced by co-expression of hNIS and hTPO genes were determined in transfected and non-transfected PC-3 cells. Significantly higher uptake (6.58 ± 0.56 fold, at 1 h post-incubation) and prolonged retention (5.47 ± 0.36 fold, at 1 h of cell efflux) of radioiodine ((125)I) were observed in hNIS and hTPO co-expressed PC-3 cells as compared to non-transfected PC-3 cells. We concluded that the new virus vector displayed favorable radioiodine uptake and retention properties in hNIS-hTPO transfected PC-3 cells. Our study will provide valuable information on improving the efficacy of hNIS-hTPO co-mediated radioiodine gene therapy.