[Expression of HER2/neu in meningiomas: an immunohistochemistry and fluorescence in situ hybridization study]

To investigate the expression of HER2/neu, Ki-67 and TK1 protein in meningiomas in correlation with tumor grades and recurrence.

Twenty cases of each of the following types of meningiomas were selected for the study, namely: the benign non-recurrent, recurrent benign, atypical and malignant, according to the World Health Organization (WHO) histological classification of nervous system, 2007. Immunohistochemistry study for HER2/neu, Ki-67 and TK1 protein was performed. HER2/neu gene amplification was detected using FISH. Cases with HER2 protein overexpression were studied by immunohistochemistry staining. The results of the biomarker assays were also used to study the correlationship with the tumor grades and tumor recurrency.

Immunohistochemistry showed that the positive rates of HER2 expression in non-recurrence benign group, recurrence benign group, atypical group and malignant group were 3 cases (15%), 6 cases (30%), 7 cases (35%), and 10 cases (50%), respectively (P < 0.05). A higher tumor grade was correlated with a higher rate of HER2/neu expression. The Ki-67 and TK1 labeling index (LI) in non-recurrence group were lower than those in the atypical or malignant group (P < 0.05), whereas the atypical group had lower LI than that of the malignant group (P < 0.05). Higher levels of LI of Ki-67 and TK1 were correlated with higher tumor grades and recurrence of the benign meningiomas (P < 0.05). Expression of HER2 was positively correlated with Ki-67 and TK1 (r = 0.445, P < 0.01; r = 0.501, P < 0.01, respectively), and there was a positive correlation between Ki-67 and TK1 (r = 0.450, P < 0.01) as well. HER2/neu gene copy amplification in 7 of 26 cases (26.9%) of HER2 immunopositive meningiomas. The rates of HER2/neu gene amplification were 0 in tumors with 1+ immunopositivity, 4/6 in tumor with 2+ immunopositivity and 3/4 in tumor with 3+ immunopositivity. HER2/neu gene amplification in 3+ and 2+ immunopositive cases had no statistical significance (P > 0.05). Aneuploidy of chromosome 17 existed in 9 of 26 of HER2 immunopositive meningiomas (34.6%). However, the rates of chromosome 17 aneuploidy had no significant difference among tumors with variable HER2/neu imumopositivity (P > 0.05).

High levels of HER2 and Ki-67 or TK1 expression correlate with the increase of tumor grades and tumor recurrence. HER2/neu gene amplification is seen in a subset of meningiomas with the protein expression (26.9%). A combination of biomarker study including HER2/neu, Ki-67 and TK1 may be useful in predicting the biological behavior of meningiomas.