Figure 1. Analysis of GEPIA2 outputs. (A) Comparisons of MUC18
expression levels between tumor and nontumor control tissues (the
expression levels were significantly different between tumor and normal
tissues); red, tumor expression levels; black, nontumor expression
levels; *, p < 0.05. (B) The prognostic impact of MUC18
expression based on the survival heatmap. The heatmap shows the hazard
ratios on a logarithmic scale (log10) for MUC18. The red and blue blocks
denote higher and lower risks, respectively. The rectangles with red
frames mean the significant unfavorable results in prognostic analyses.
3.2 Production and Characterization of89Zr-IP150
The MALDI-TOF-MS results showed that the molecular weight of the IP150
mAb was 148533.772 D (Figure 2B), the molecular weight of the DFO-IP150
mAb was 151917.775 D (Figure 2C), and about ~four DFO
were conjugated to each IP150 molecule. The EC50 values of the MUC18
protein for IP150 and DFO-IP150 were 2.2 nM (R2=0.87)
and 3.07 nM (R2=0.96), respectively (Figure 2E),
suggesting that the conjugation of DFO has no impact on the binding
activity of IP150. After 60 minutes of reaction at 37 °C, the
radiolabeling rate was 97.5% (Figure 2D), and the radiochemical purity
was determined with a TLC silica gel strip. 89Zr-IP150
has a high radiochemical yield (~ 99%) and high
specific activity (28.22 ± 8.53 GBq/µmol) (Supplementary Figure 1A and
Table 1). The 89Zr loss of the89Zr-IP150 probe was less than 5% after 120 hours
(incubation in PBS and 5% HSA at 37 °C), indicating that the probe has
good stability in vitro (Supplementary Figure 1B, 1C), which is
acceptable for preclinical studies.