Sensitivity Assessment of Wilms tumor gene (WT1) expression in Glioblastoma Using qPCR and Immunohistochemistry and its association with IDH1 mutation, and recurrence interval
Background The Wilms tumor 1 (WT1) gene has recently been shown to play a role in gliomagenesis, making it a potential immunotherapy target in glioblastomas. We aimed to investigate the most sensitive method to detect WT1 expression in glioblastoma and explore relationship between WT1 expression and isocitrate dehydrogenase-1 (IDH1) mutation. Methods Clinical and biological data were collected from 44 patients with totally resected glioblastomas, treated with adjuvant therapies, in the period
... es, in the period between 2015 and 2019. WT1 protein expression was assessed in all cases using IHC while its gene expression was assessed in 13 clustered samples using quantitative polymerase chain reaction (qPCR). IDH1 mutation was assessed using immunohistochemistry (IHC). McNemar test was used to compare the sensitivity between IHC and RT-qPCR for WT1 gene expression detection. Kaplan Meier curves were used to compare the distribution of recurrence-free interval (RFI) between IDH1 and WT1 expression groups. Results The mean age was 54-years, with a male to female ratio 1.45. IDH1-wildtype was found in 26 cases (59.1%) and the remining 18 cases (40.9%) were IDH1-mutant. Through IHC, WT1 was overexpressed in 32 cases (72.7%), partially expressed in 9 cases (20.5%) and not expressed in only three cases (6.8%). For the 13 cases tested by qPCR, 6 cases showed WT1 gene up-regulation and 7 cases showed WT1 down-regulation. There was no significant difference in WT1 expression among cases with different RNA concentrations regardless the testing method (P-value < 0.05). However, the difference between IHC and qPCR revealed 83% sensitivity, 28.5% specificity and 53% accuracy. IDH1-mutant cases with WT1 overexpression showed significant difference in recurrence interval (P-value < 0.048). This significance was not seen among IDH1-mutant cases with WT1 partial or no expression (P-value = 0.56). There was also no significant difference in recurrence interval among IDH1-wildtype cases with WT1 partial or overexpression (P-value = 0.83). Conclusions Parallel testing for WT1 expression using IHC and qPCR is not reliable. However, IHC provides more accurate results than does qPCR, which runs on fragmented tissue with indeterminant RNA concentrations. Moreover, IDH1-mutant glioblastomas with WT1 overexpression are associated with slow recurrence interval particularly if temozolomide with additional chemotherapies are used.