title: Neuroglobin and myoglobin in non-small cell lung cancer: expression, regulation and prognosis.
abstract: Globins are respiratory proteins involved in oxygen metabolism, which is a critical factor in tumor growth and progression. The status of neuroglobin and myoglobin is largely unknown in human malignancies, including lung cancer. The aim of this study was to explore mRNA expression profiles, potential regulatory mechanisms and clinicopathological associations of neuroglobin and myoglobin in non-small cell lung cancer (NSCLC). We screened 208 surgically resected NSCLC specimens and a panel of lung normal and cancer cell lines. The mRNA expression of neuroglobin, myoglobin and hypoxia markers (HIF1α and VEGFa) was measured with qRTPCR, while neuroglobin promoter methylation was assessed with Pyrosequencing. Neuroglobin and myoglobin were upregulated in the tumor samples compared to normal tissue (p=1.3×10(-22) and p=1.9×10(-9), respectively). Neuroglobin was more frequently overexpressed in squamous cell carcinomas (SqCCL) than adenocarcinomas. Overexpression of myoglobin was more profound in adenocarcinomas, which correlated with poor survival (p=0.013). Neuroglobin promoter was hypermethylated in 30.8% of NSCLC cases, which correlated with neuroglobin mRNA downregulation. The epigenetic regulation of neuroglobin was confirmed by treating lung cell lines with 5'azadeoxycytidine and/or trichostatin A. Expression of both genes correlated with the expression of HIF1α (neuroglobin: p=3.8×10(-5), myoglobin: p=1.1×10(-11)). Myoglobin expression was also associated to that of VEGFa (p=2.1×10(-7)). Hypoxia-dependent upregulation of both globins was validated in vitro. In summary, neuroglobin and myoglobin overexpression in NSCLC is associated with histological subtype, hypoxia and, in case of neuroglobin - epigenetic regulation. Myoglobin expression may have potential significance in the prognostication of lung adenocarcinomas.
authors.affiliation: University of Liverpool Cancer Research Centre, Roy Castle Lung Cancer Research Programme, Liverpool L3 9TA, UK.
authors.forename: Urszula
authors.initials: U
authors.lastname: Oleksiewicz
authors.forename: Nikoleta
authors.initials: N
authors.lastname: Daskoulidou
authors.forename: Triantafillos
authors.initials: T
authors.lastname: Liloglou
authors.forename: Kelly
authors.initials: K
authors.lastname: Tasopoulou
authors.forename: Julie
authors.initials: J
authors.lastname: Bryan
authors.forename: John R
authors.initials: JR
authors.lastname: Gosney
authors.forename: John K
authors.initials: JK
authors.lastname: Field
authors.forename: George
authors.initials: G
authors.lastname: Xinarianos
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D045744:Cell Line, Tumor; D019175:DNA Methylation; D005260:Female; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009211:Myoglobin / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D000078787:Neuroglobin; D011379:Prognosis
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009211:Myoglobin; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D005914:Globins