B109
Ectopic expression of Cytoglobin (CYGB) affects phenotypic characteristics and properties of lung cancer cells
Urszula Babiszkiewicz, Triantafillos Liloglou, John Field, George Xinarianos
Roy Castle Lung Cancer Research Programme, University of Liverpool, School of Cancer Studies, UK
Background
Cytoglobin (CYGB) is a recently discovered member of the globin family genes, whose molecular function remains poorly understood. It has been shown that CYGB is engaged in cellular response to hypoxic and oxidative stress conferring cytoprotective features. CYGB expression has been found to be reduced in human cancers due to promoter hypermethylation and loss of heterozygosity. Recent findings suggested that CYGB might act as a tumour suppressor gene (TSG). The aim of this study was to investigate in more detail the potential TSG properties of CYGB in lung cancer.
Method
A squamous cell lung cancer cell line (Calu1) was used to create stable transfectants overexpressing CYGB. These cells were further utilised in functional studies evaluating several cellular characteristics, including growth, cell death, migration and transformation abilities. Cell proliferation was measured with MTT and Apoglow assays. The quantification of ADP:ATP ratio was used to assess cell death. Transformation abilities were studied with the soft agar assay and migration was tested using the wound healing assay.
Results
Restoration of CYGB expression was found to diminish the proliferation rate of lung cancer cells. We found that the observed reduction in the growth is not caused by cell death, as neither apoptosis nor necrosis were detected with the Apoglow assay. CYGB positive cells showed minor decrease in their migration rates and markedly suppressed ability to form colonies in soft agar. Colony formation in soft agar was reduced up to 50% (p<1.5x10-4), revealing impaired transformation capacity upon CYGB overexpression.
Conclusion
Our findings demonstrate that ectopic expression of CYGB in lung cancer cells may lead to reduced proliferation, migration and transformation of the cells. These data provide further strong support of the hypothesis that CYGB may function as a tumour suppressor gene.
Acknowledgements
This study was supported by the Roy Castle Lung Cancer Foundation
