Background Emphysema is an independent risk factor for the development of lung cancer in smokers. Activation of oncogenic signalling proteins AKT and ERK by phosphorylation has an established role in the development of lung cancer and has also been implicated in the pathogenesis of emphysema. The aim of this study was to compare the protein level and phosphorylation status of AKT and ERK in paired lung cancer and emphysema tissue using a highly sensitive phosphoprotein analysis approach.
Methods An antibody-based, nanocapillary isoelectric focusing (cIEF) assay was used to determine the relative quantities and phosphorylation status of AKT and ERK in tumour and matched lung tissue from patients, with or without evidence of emphysema, undergoing curative resection for non-small cell lung cancer.
Results 20 patients with adenocarcinoma (n=9) or squamous cell carcinoma (n=11) of the lung were included (mean age 67.3 years (SD 7.5, range 47–80 years)), 12 were men and all were current (n=10) or former smokers (n=10). Paired macroscopically normal lung tissue was either histologically normal (n=7) or showed emphysema (n=13). Total and phosphorylated AKT levels were fourfold (p=0.0001) and fivefold (p=0.001) higher in tumour compared with matched lung, respectively. There was no correlation with tumour histology, stage or differentiation; however, total AKT signal in tumour was significantly correlated with fluorodeoxyglucose avidity on positron emission tomography-CT scan (r=0.53, p=0.035). Total ERK was not differentially expressed, but doubly phosphorylated (activated) ERK was threefold higher in emphysema (23.5%, SD 9.2) than either matched tumour (8.8%, SD 8.6) or normal lung tissue (8.3%, SD 9.0) and correlated with the histological severity of emphysema (p=0.005).
Conclusions cIEF offers opportunities for quantifying subtle shifts in the phosphorylation status of oncoproteins in nanogram amounts of lung tissue. ERK activation is a feature of emphysema.
- Lung Cancer
- Non-Small Cell Lung Cancer
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Correction notice This article has been corrected since it published Online First. The Open Access licence has been updated to CC BY.
Contributors PAJC and ADW devised the study. PAJC, RB, RS ran the clinical aspects of the study. LJ analysed the pathological samples. PAJC, EJC, MA-O’D, AP developed the assays. PAJC, EJC, MA-O’D, MW, RH, MP performed the laboratory work. PAJC, EJC, MA-O’D, MP analysed the data. ADW supervised all aspects of the laboratory work and provided the cIEF platform. All authors contributed to the writing and review of the manuscript and agreed its contents.
Funding This work was supported by grants from Leukaemia Lymphoma Research and The North West Lung Centre Charity.
Competing interests None declared.
Ethics approval NRES Committee North West—Greater Manchester Central.
Provenance and peer review Not commissioned; externally peer reviewed.
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