Amplification and sequence changes in epidermal growth factor receptor (EGFR) gene in glioblastomas

D Arjona BSc^a, ME Alonso BSc^a, P Gonz, Ã

^aLab. Oncogenética Molecular, Dpt. C. Experimental and, Pº Castellana 261, Madrid, ^bDpt. Anatomía Patológica, Hospital Universitario La Paz, Pº Castellana 261, Madrid, Spain, ^cDpto. Neurocirugía, Hospital del Río Hortega, Valladolid, Spain, ^dDpt. Neurocirugía, Hospital Puerta de Hierro, Madrid, Spain, ^eInstituto Investigaciones Biomédicas, CSIC, Madrid, Spain

AIM: The primary alteration of EGFR in glioblastomas appears to be gene amplification present in about 30-40% of tumours. Additional evidence is available suggesting that other EGFR mutations might contribute to an abnormal gene function. METHODS: To determine the frequency and diversity of EGFR alterations in glioblastomas we performed a PCR/SSCP analysis of the complete coding region of this gene in a series of 43 glioblastomas. In parallel, we also determined the presence of EGFR amplification by either Southern blot or Real-Time quantitative PCR. RESULTS: Gene amplification was evidenced in 13 cases (30%), and several sequence variations (mutations or polymorphisms) were identified, as follows: delG at E6+72 (intron 6) in one tumour; T>C at E18-109 position of intron 17 (one case); C>G at E22-14 of intron 21 (one case); changes C>T at nucleotide 2025 (exon 15) and A>G at 2547 (exon 20) with no changes of Ala 589 and Gln 263, respectively presented in three and two tumours; transversion A>C at nucleotide 2325 (exon 18) with change Lys689Asn (one tumour); insCCC at position 2498 (ins Pro 748) (exon 20) and the polimorphic change G>A at position 1748 (Arg>Lys) (frequencies: GA 16%; AA 56%; GG 28%);. CONCLUSIONS: Non-polymorphic sequence variations primarily occurred in tumours with EGFR amplification -in seven of the 13 cases (54%)-, suggesting such gene mutations are frequently associated to gene amplification.

Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 893 (Molecular pathology).