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.