No abstract

Exhaled breath condensate (EBC) contains extracellular DNA that may originate from pathological lesions of the respiratory tract and can be a genetic marker of pulmonary malignancy. We tested whether complete surgical excision of lung cancer will decrease exhalation of mutated KRAS oncogene. Fifty seven patients with clinical diagnosis of lung cancer and detectable KRAS mutations in pre-surgery EBC-DNA were qualified for surgical treatment. Point mutations at codon 12 of KRAS oncogene were detected using mutant-enriched PCR technique in DNA from pre-surgery blood, EBC collected before, 7 and 30 days after surgery and from specimens of resected tumor and normal pulmonary parenchyma. The ratio of mutated to wild type KRAS DNA (R mut/wild KRAS) was calculated for each specimen after electrophoresis and densitometry of the final amplification and digestion product. In 46 patients non-small cell lung cancer (NSCLC) and in 11 benign lesion (BL) were confirmed. All blood and tumor specimens were positive for KRAS mutations, while 41 specimens of normal pulmonary parenchyma were negative. In NSCLC patients pre-surgery EBC R mut/wild KRAS of 0.20 ± 0.03 decreased by 1.3- and 3.7-times (p < 0.001) at 7th and 30th day and 10 EBC specimens at day 30th became negative. The highest R mut/wild KRAS was found in NSCLC specimens - 1.36 ± 0.29 while the lowest in pulmonary parenchyma - 0.02 ± 0.03 (p < 0.001). R mut/wild KRAS in EBC did not correlate with the blood and cancer ratios. Determination of mutated KRAS oncogene in EBC can be potentially helpful in the follow-up of surgical treatment of pulmonary malignancy.

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.

Despite therapeutic advances, lung cancer remains one of the most common causes of cancer-related death in the world. There is a need to develop biomarkers of diagnostic and/or prognostic value and to translate findings in basic science research to clinical application. Tumor suppressor genes (TSGs) represent potential useful markers for disease detection, progression and treatment target. We tried to elucidate the role of three 3p21.3 TSGs: DLEC1, ITGA9 and MLH1, in non-small cell lung cancer (NSCLC). We assessed their expression pattern by qPCR in 59 NSCLC tissues and in the matched macroscopically unchanged lung tissues. Additionally, we analyzed gene promoter methylation status by methylation-specific PCR in NSCLC samples. We did not find significant correlations between gene expression and methylation. In case of DLEC1 and ITGA9, expression levels were decreased in 71-78 % of tumor samples and significantly different between tumor and normal tissues (P = 0.0001). It could point to their diagnostic value. ITGA9 could also be regarded as a diagnostic marker differentiating NSCLC subtypes, as its expression level was significantly lower in squamous cell carcinoma (P = 0.001). The simultaneous down-regulation of DLEC1 and ITGA9 was observed in 52.5 % of NSCLCs. MSPs revealed high frequencies of gene promoter methylation in NSCLCs: 84 % for DLEC1 and MLH1 and 57 % for ITGA9. Methylation indexes reflected moderate gene methylation levels: 34 % for ITGA9, 27 % for MLH1 and 26 % for DLEC1. However, frequent simultaneous methylation of the studied genes in more than 50 % of NSCLCs suggests the possibility of consider them as a panel of epigenetic markers.

The knowledge of negative prognostic factors can appear to be a crucial tool enabling one to work out a better therapeutic strategy for high-risk patients with AM.