Analysis of PIK3CA mutations in tumours from patients with non-small cell lung cancer using pyrosequencing

Abstract: A subgroup of non-small cell lung cancer (NSCLC) cases harbour mutations in classical oncogenes, which can affect therapy response and prognosis. By therapeutically targeting the corresponding proteins with inhibitory drugs, the clinical outcome for these lung cancer patients may be improved. One of these oncogenes is the phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) which encodes the catalytic subunit of the phosphatidylinositol 3 kinase (PI3K). PIK3CA is a central regulator in the PI3K/Akt/mTOR pathway, which controls cell growth and apoptosis. Mutations in the PIK3CA gene are considered to up-regulate the kinase activity in tumour cells and through that dysregulate fundamental cellular processes. PI3K inhibitors are currently tested in clinical trials and present a promising therapy option in lung cancer patients. In this study, a pyrosequencing assay for detection of PIK3CA mutations in tumours from patients with NSCLC was established. The three "hot-spot" codons 542, 545 and 1047 of the PIK3CA gene were analysed. The sensitivity of this assay was determined to the presence of 5 % of mutant alleles. In agreement with previous reports, three of the 60 lung cancer cases revealed PIK3CA mutations (5 %). All mutations occurred in exon 9 codon 542 or 545. In line with previous reports, two of the three samples harboured concurrent mutation in the EGFR or KRAS gene. The established pyrosequencing analysis for PI3KCA mutations provides a reliable and cost-effective assay for clinical diagnostics. The determination of the PI3KCA mutation status may help to distinguish patients for treatment targeting the PI3K pathway.