Results showed a high frequency of NF2 gene mutations (40%), increased 22q LOH as aggressiveness increased, frequent losses and gains by MLPA in benign meningiomas, and gene expression silencing by hypermethylation.
The immunoprofile was similar to normal cap cells with one exception; whereas normal cells were uniformly negative forPR, nuclear positivity was seen in 64% of hyperplasias, a frequency similar to that of benign meningiomas.
The reported patient, in addition to glioma, had suffered from benign meningioma in the past but did not show any clinical signs of Cowden disease or other hereditary diseases typically associated with PTEN germline mutations.
We also compared the average change in expression level of the three genes (CCNB1, CDC2, and MKI67) in atypical/anaplastic versus benign meningiomas; the difference between the groups was highly significant (P<0.001).
One anaplastic meningioma, three atypical meningiomas, and one benign meningioma without a demonstrated homozygous deletion or mutation of CDKN2A, p14(ARF), or CDKN2B lacked detectable transcripts from at least one of these genes.
In order to investigate the disruption of the p53 function in a patient presenting this mutation and the TP53Arg72Pro polymorphism who had so far suffered five malignant tumors and a benign meningioma, we tested her fibroblasts in response to DNA damage by evaluating the proliferation rate, apoptosis, and disruption of the TP53 pathway.
All cases of atypical and anaplastic meningiomas were positive for c-myc protein and mRNA by immunohistochemistry and in situ hybridisation, respectively, while all 10 benign meningiomas were negative for c-myc immunostaining, with only one benign tumour positive for c-myc mRNA.