Abstract
PurposeMutated KRAS oncogene in exhaled breath condensate (EBC) can be a genetic marker of non-small cell lung cancer (NSCLC). However, a possibility of inhomogeneous distribution in cancer tissue and intratumor heterogeneity of KRAS mutation may decrease its significance. We investigated a status of KRAS point mutation and its sequence at codon 12 in 51 NSCLC patients after tumor resection. The comparison of KRAS mutation status between EBC–DNA and cancer tissue was performed in 19 cases.MethodsFive cancer tissue samples from disparate tumor regions and one from normal lung were harvested at surgery. EBC was collected for DNA analysis the previous day. KRAS point mutations at codon 12 were detected using mutant-enriched PCR technique and pyrosequenced.ResultsForty-six cancers revealed concordance of KRAS mutation status: 27 contained mutated KRAS and 19 had only wild KRAS. Five NSCLCs revealed inhomogeneous distribution of KRAS mutation. Two different mutations were found in 14 NSCLCs and the most frequent one was G12D and G12V (n = 8). No mutated KRAS was found in normal lung. The concordance ratios of KRAS sequence in codon 12 between EBC–DNA and cancer were 18/19 for NSCLC patients and 11/12 for KRAS mutation positive NSCLC.ConclusionsIntratumor heterogeneity and inhomogeneous distribution of KRAS point mutation in codon 12 in cancer tissue can occur in NSCLCs. There was a high accordance between KRAS mutation status in EBC–DNA and cancer tissue in NSCLC patients what suggests usefulness of monitoring KRAS mutation in EBC–DNA as a biomarker of NSCLC.
Highlights
Exhaled breath condensate (EBC) composed of droplets of airway epithelial lining fluid (ELF) and condensed water vapor contains variety of biomolecules with potential for non-invasive monitoring of various pathological processes in the airways (Dent et al 2013; Liang et al 2012; Kwiatkowska et al 2012; Stolarek et al 2010)
For instance: (a) sequence analysis of p53 gene mutations revealed different point mutations in exhaled breath condensate (EBC) and corresponding tumor tissue in non-small cell lung cancer (NSCLC) patients (Gessner et al 2004), (b) the ratio of mutated to wild KRAS gene in EBC of NSCLC patients decreased after complete tumor resection, this parameter did not correlate with the corresponding ratios in blood and tumor tissue (Kordiak et al 2012) and (c) comparison of KRAS mutations in excised NSCLC and serum showed higher ratio of positive results in serum than in tumor and only one of 51 studied patients carried the same mutation in both specimens (Ramirez et al 2003)
We found that intratumor heterogeneity of KRAS point mutation at codon 12 and inhomogeneous distribution of this mutation over the cancer tissue can occur in NSCLCs
Summary
Exhaled breath condensate (EBC) composed of droplets of airway epithelial lining fluid (ELF) and condensed water vapor contains variety of biomolecules (e.g. proteolytic enzymes, lipid peroxidation products, reactive oxygen and nitrogen species) with potential for non-invasive monitoring of various pathological processes in the airways (Dent et al 2013; Liang et al 2012; Kwiatkowska et al 2012; Stolarek et al 2010). They can limit the usefulness of EBC as a diagnostic material for sensitive and specific monitoring of selected genetic biomarkers of pulmonary malignancy To solve this issue we decided to conduct a prospective study on plausible intratumor heterogeneity of KRAS oncogene point mutations at codon 12 in five different NSCLC samples from each cancer specimen, collected according to standardized protocol from 51 tumors after their complete surgical resection. To compare KRAS mutations in DNA extracted from pre-surgery EBC, blood samples and cancer tissue in 19 NSCLC patients were collected
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
