RELIABILITY OF DIFFERENTIAL PCR FOR THE DETECTION OF EGFR AND MDM2 GENE AMPLIFICATION IN DNA EXTRACTED FROM FFPE GLIOMA TISSUE

A series of 43 human gliomas, consisting of 30 glioblastomas, 7 anapla stic astrocytomas, 3 low grade astrocytomas, 2 ependymomas, and 1 olig odendroglioma, was studied for amplification of the epidermal growth f actor receptor (EGFR) and mouse double minute 2 (MDM2) genes. DNA extr acted from formalin-fixed, paraffin-embedded tissue sections was analy zed by differential PCR and the results were compared with slot blot e xamination of DNA extracted from frozen tissue from the same neoplasms . Twelve glioblastomas (40%) showed amplification of the EGFR gene, an d overexpression of EGFR was evident in each of these tumors as indica ted by the immunoperoxidase technique. Two of the tumors with EGFR gen e amplification also revealed amplification of the MDM2 gene, while on e additional glioblastoma revealed MDM2 amplification only. A 100% con cordance in the detection of amplification was observed between differ ential PCR and slot blot analysis; consequently, these results indicat e that differential PCR using DNA extracted from archival tissue secti ons is a reliable method of demonstrating gene amplifications in glial tumors.