Neuroglobin and myoglobin in non-small cell lung cancer: expression, regulation and prognosis.

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

Neuroglobin and myoglobin in non-small cell lung cancer: expression, regulation and prognosis.

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

Cytoglobin has bimodal: tumour suppressor and oncogene functions in lung cancer cell lines.

Cytoglobin (CYGB) is frequently downregulated in many types of human malignancies, and its exogenous overexpression reduces proliferation of cancer cells. Despite its implied tumour suppressor (TSG) functions, its exact role in carcinogenesis remains unclear as CYGB upregulation is also associated with tumour hypoxia and aggressiveness. In this study, we explore the TSG role of CYGB, its influence on the phenotype of cancerous cells under stress conditions and the clinical significance of CYGB expression and promoter methylation in non-small cell lung cancer (NSCLC). DNA methylation-dependent expression silencing of CYGB is demonstrated in both clinical samples and cell lines. CYGB promoter was more frequently methylated in lung adenocarcinomas (P = 1.4 × 10(-4)). Demethylation by 5'-azadeoxycytidine partially restored CYGB expression in cell lines. Interestingly, trichostatin A triggered upregulation of CYGB expression in cancer cell lines and downregulation in non-tumourigenic ones. CYGB mRNA expression in NSCLC surgical specimens correlated with that of HIF1α and VEGFa (P < 1 × 10(-4)). Overexpression of CYGB in cancer cell lines reduced cell migration, invasion and anchorage-independent growth. Moreover, CYGB impaired cell proliferation, but only in the lung adenocarcinoma cell line (H358). Upon hydrogen peroxide treatment, CYGB protected cell viability, migratory potential and anchorage independence by attenuating oxidative injury. In hypoxia, CYGB overexpression decreased cell viability, augmented migration and anchorage independence in a cell-type-specific manner. In conclusion, CYGB revealed TSG properties in normoxia but promoted tumourigenic potential of the cells exposed to stress, suggesting a bimodal function in lung tumourigenesis, depending on cell type and microenvironmental conditions

TPL2 kinase is a suppressor of lung carcinogenesis

Lung cancer is a heterogeneous disease at both clinical and molecular levels, posing conceptual and practical bottlenecks in defining key pathways affecting its initiation and progression. Molecules with a central role in lung carcinogenesis are likely to be targeted by multiple deregulated pathways and may have prognostic, predictive, and/or therapeutic value. Here, we report that Tumor Progression Locus 2 (TPL2), a kinase implicated in the regulation of innate and adaptive immune responses, fulfils a role as a suppressor of lung carcinogenesis and is subject to diverse genetic and epigenetic aberrations in lung cancer patients. We show that allelic imbalance at the TPL2 locus, up-regulation of microRNA-370, which targets TPL2 transcripts, and activated RAS (rat sarcoma) signaling may result in down-regulation of TPL2 expression. Low TPL2 levels correlate with reduced lung cancer patient survival and accelerated onset and multiplicity of urethane-induced lung tumors in mice. Mechanistically, TPL2 was found to antagonize oncogene-induced cell transformation and survival through a pathway involving p53 downstream of cJun N-terminal kinase (JNK) and be required for optimal p53 response to genotoxic stress. These results identify multiple oncogenic pathways leading to TPL2 deregulation and highlight its major tumor-suppressing function in the lung