Fig. 4.
Cell surface binding and internalization of radiotracer [64Cu]CB-TE1A1P-Y3-TATE by SIV-transduced cells. (a) Cell surface binding and (b) internalization of radiotracer in HCT116 cells and HCT116 cells transduced with SIVmac239-GFP-T2A-SSTR2 or SIVmac239-GFP; n = 2 for each data point; bar, sd. Note that 9 % of cells were transduced with SIVmac239-GFP-T2A-SSTR2 and 57 % of cells were transduced with SIVmac239-GFP based on GFP expression by FACS. (c) Blocking of SSTR2 in HCT116 cells transduced with SIVmac239-GFP-T2A-SSTR2 by incubating with 2 μg octerotide for 2 h to demonstrate the uptake specificity of radiotracer was analysed on cell surface binding (surface) and internalization (cell lysate). (d) Western blotting of HCT116 and CEMx174 cells transduced with SIVmac239-GFP-T2A-SSTR2 and SIVmac239-GFP was performed using antibodies against SSTR2 and α-tubulin. HCT116 cells stably expressing SSTR2 previously established by transfection were used as a positive control (SSTR2) and non-expressing HCT116 were used as a negative control (NC).