Identification of Astrocytoma Blood Serum Protein Profile

Abstract

High-grade astrocytomas are some of the most common and aggressive brain cancers, whose signs and symptoms are initially non-specific. Up to the present date, there are no diagnostic tools to observe the early onset of the disease. Here, we analyzed the combination of blood serum proteins, which may play key roles in the tumorigenesis and the progression of glial tumors. Fifty-nine astrocytoma patients and 43 control serums were analyzed using Custom Human Protein Antibody Arrays, including ten targets: ANGPT1, AREG, IGF1, IP10, MMP2, NCAM1, OPN, PAI1, TGFβ1, and TIMP1. The decision tree analysis indicates that serums ANGPT1, TIMP1, IP10, and TGFβ1 are promising combinations of targets for glioma diagnostic applications. The accuracy of the decision tree algorithm was 73.5% (75/102), which correctly classified 79.7% (47/59) astrocytomas and 65.1% (28/43) healthy controls. The analysis revealed that the relative value of osteopontin (OPN) protein level alone predicted the 12-month survival of glioblastoma (GBM) patients with the specificity of 84%, while the inclusion of the IP10 protein increased model predictability to 92.3%. In conclusion, the serum protein profiles of ANGPT1, TIMP1, IP10, and TGFβ1 were associated with the presence of astrocytoma independent of its malignancy grade, while OPN and IP10 were associated with GBM patient survival.

Keywords: Protein Antibody Array; astrocytoma; decision tree; glioblastoma; serum proteins; survival.

Figure 1

Proteomic analysis of ten proteins in preoperative blood serum in astrocytoma patients and controls. Box plots of relative expression measurements of proteins ANGPT1, AREG, IGF1, IP10, MMP2, NCAM1, OPN, PAI1, TGFβ1, and TIMP1 obtained by protein array analysis of different malignancy grade astrocytoma patients’ serum and normal controls. The line inside each box represents the median; the lower and upper edges of the boxes represent the 25th (first quartile) and 75th (third quartile) percentiles, respectively; the upper and lower edges of the boxes represent the Tukey’s whiskers.

Figure 2

Decision tree classification diagram of protein relative values from astrocytoma patients and controls, using protein microarrays. Potential diagnostic serum protein profile composed of ANGPT1, TIMP1, IP10, and TGFβ1. The numbers in the root node (top), descendant nodes (hexagons), and terminal nodes (rectangles) represent the classes (astrocytoma patients and controls, n represents the sum of astrocytoma patients and controls). The number below the root and descendant nodes indicate the relative values of protein.

Figure 3

Potential prognostic serum protein profile for glioblastoma patients composed of OPN and IP10. (A) Glioblastoma patient decision tree with the clinical feature of one-year post-surgery survival. The numbers in the root node (top), descendant nodes (hexagons), and terminal nodes (rectangles) represent the classes (glioblastoma patients who survived less than one year after surgery and glioblastoma patients who survived more than one year after surgery); n = sum of glioblastoma patients in a class. The numbers below the root and descendant nodes indicate the relative values of protein. (B–D) Kaplan–Meier survival curves. (B) Kaplan–Meier analysis of glioblastoma patient overall survival differences between combined OPN and IP10 protein expression groups. Low- vs. high-level protein patient group median survival 16 months versus 7.56 months (log-rank test, p = 0.0275). (C) Kaplan–Meier analysis of glioblastoma patient overall survival between OPN protein relative expression groups, were OPN low level means that relative OPN protein value is <0.01277, and OPN high level means that relative OPN protein value is ≥0.01277. Low- vs. high-level protein patient group median survival 20 months versus 7.71 months (log-rank test, p = 0.0104). (D) Kaplan–Meier analysis of glioblastoma patient overall survival in different IP10 protein relative expression groups, where IP10 low level means that relative IP10 protein value is <0.01897, and IP10 high level means the value is ≥0.01897. Low- vs. high-level protein patient group median survival 13 months versus 8.84 months (log-rank test, p = 0.735).