Aberration of Egfr1, Her2/neu, and K-ras in non-small cell lung cancers (NSCLC) treated with gefitinib in expanded access program

Egfr1 and Her2/neu are members of the EGFR (HER) family and play an important role in the pathogenesis of certain tumors. Indeed, overexpression of the Egfr1 was frequently detected in lung cancers. Enhanced gene expression may be due to amplification of the gene, and it is associated with constitutive activation of the EGFR1 signaling. Likewise, somatic mutations in the kinase domain of egfr1 (exons 18–21) result in ligand-independent transduction, particularly in NSCLCs. K-ras mutations contribute to the development of NSCLC independently on egfr1 mutations. Because K-ras is one of the downstream molecules in the EGFR signal transduction, and egfr1 and k-ras mutations are mutually exclusive, and this suggest different carcinogenesis pathways involved in NSCLC. Activating aberrations in egfr1 are associated with clinical responses to tyrosine kinase inhibitors gefitinib and erlotinib. In contrast, mutations in K-ras signify resistance to EGFR1 targeted therapy.
In our retrospective study we analyzed EGFR1 status in NSCLC patients treated with gefitinib within the Expanded Access Program in the Czech Republic. Genomic DNA was isolated from laser capture microdissected tumors cells in order to exclude non-malignant cells from the analysis. Extracted DNA was amplified by nested PCR for the most frequent egfr1 mutations in exon 19 and 21 and K-ras mutations in exon 1. DNA fragment length polymorphism analysis of the PCR product was used to screen samples for egfr1 exon 19 deletion mutations. Direct DNA sequencing was used to detect/confirm egfr1 (exons 19 and 21) and k-ras (exon 1) mutations. The expression of Egfr1 and Her2 proteins was assessed by immunohistochemical staining (IHC) and gene amplification was detected using fluorescence in situ hybridization(FISH).
Acknowledgement: Study was supported by projects MŠMT (6198959216), MPO 1H-PK/45 and by AstraZeneca, Czech Republic