Increased NG2 and SOX2 expression is associated with high-grade choroid plexus tumors

The World Health Organization classification of choroid plexus tumors (CPT) includes three distinct grades: Choroid plexus papilloma (CPP), atypical choroid plexus papilloma (ACPP) and choroid plexus carcinoma (CPC). The molecular basis for these pathological distinctions may help to stratify tumors and provide an insight into the clinical behavior of CPTs. In the present study, the progenitor and stem cell markers neuron glia antigen-2 (NG2) and sex-determining region Y-box 2 (SOX2) were investigated as potential biomarkers that may distinguish between distinct CPT grades. Immunohistochemistry was used to determine the expression of NG2 and SOX2 in CPTs (n=34) from Chinese patients (21 males and 13 females) with a mean age of 31.1 years (range, 1-63 years). The proportion of cells stained were scored using a scale between 0 and 3+, where 0 represents no staining and 3+ represents strong staining, and mean scores for each marker were determined on the basis of tumor grade. Pathological diagnosis revealed a distribution of cases as follows: CPP, 25; ACPP, 5; and CPC, 4. NG2 and SOX2 were expressed in CPTs of all grades. The mean labeling indices for CPP, ACPP and CPC were 1.12, 1.80 and 2.75 for NG2, respectively, and 1.20, 2.00 and 3.00 for SOX2, respectively. Statistical analysis of the mean labeling indices revealed a significant association between the expression of NG2 and SOX2 and CPT grade (P=0.001 and <0.001 for CPP/ACPP and CPP/CPC, respectively). The results of the present study indicated that increased expression of NG2 and SOX2 was associated with higher-grade tumors and that these markers may be useful in determining CPT grade.