Table 4. Summary of the differentially expressed proteins in plasma validated by QTAP analysis.
| Protein | AUC (95%CI) | Threshold (fmol/μL plasma) | Sensitivity (%) | Specificity (%) | Odds ratio | p value | Effect size | Fold change in plasma | Cyst fluid | Fold change in tissue | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Up-regulated proteins | ||||||||||||||
| Leucine-rich alpha-2-glycoprotein | 0.883 (0.735–1) | 272 | 85.7 | 86.7 | 39.1 | 3.84×10−3 | 1.31 | 1.73 | ± | 0.85 | + | 3.04 | ||
| Complement component C9 | 0.886 (0.768–1) | 335 | 85.7 | 80.0 | 24.0 | 3.80×10−3 | 1.32 | 1.78 | ± | 0.91 | + | 5.18 | ||
| C-reactive protein | 0.833 (0.682–0.985) | 13.0 | 85.7 | 73.3 | 16.5 | 8.49×10−2 | 0.718 | 13.9 | ± | 31.0 | + | 0.299 | ||
| Alpha-1-antichymotrypsin | 0.695 (0.484–0.907) | 3293 | 57.1 | 86.7 | 8.68 | 4.76×10−2 | 0.839 | 1.47 | ± | 0.82 | + | 13.0 | ||
| Apolipoprotein B-100 | 0.586 (0.359–0.813) | 1068 | 57.1 | 80.0 | 5.32 | 2.86×10−1 | 0.416 | 1.09 | ± | 0.30 | + | 2.46 | ||
| Down-regulated proteins | ||||||||||||||
| Gelsolin | 0.986 (0.954–1) | 672 | 100 | 93.3 | ∞ | 1.54×10−7 | 2.61 | 0.601 | ± | 0.193 | + | 1.41 | ||
| Ig alpha-1 chain C region | 0.891 (0.769–1) | 16119 | 78.6 | 93.3 | 51.1 | 2.32×10−4 | 1.58 | 0.617 | ± | 0.282 | + | 4.22 | ||
| Apolipoprotein A-IV | 0.871 (0.737–1) | 9859 | 78.6 | 93.3 | 51.1 | 2.51×10−4 | 1.57 | 0.612 | ± | 0.316 | + | 14.3 | ||
Receiver operating characteristics (ROC) analysis and Student’s t-test were performed for the absolute protein concentrations obtained by quantitative targeted absolute proteomics (QTAP) analysis of healthy plasma (n = 15) and glioblastoma (GBM) plasma (n = 14). Thresholds were determined as the points with minimum distance from 100% sensitivity and 100% specificity in the ROC curve for GBM plasma (n = 14) and healthy plasma (n = 15). AUC is the area under the ROC curve, and the range of 95% confidence interval (CI) is shown. Odds ratio was calculated as %sensitivity × %specificity / (100−%sensitivity) × (100−%specificity). The fold changes of mean plasma concentrations between healthy controls (n = 15) and GBM patients (n = 14) were determined by QTAP analysis. In the cyst fluid column, + indicates any peptide(s) derived from the protein was identified in cyst fluid by data-dependent acquisition analysis. The fold changes of mean expression levels in cytosol fractions between GBM tissues (n = 14) and noncancerous brain tissues (n = 2) were determined by QTAP analysis.