Embryo-chondrocyte expressed gene 1, downregulating hypoxia-inducible factor 1alpha, is another marker of lung tumor hypoxia.

Objective: To explore the mechanism of differentiated embryo-chondrocyte expressed gene 1 (DEC1) in the lung adenocarcinoma A549 cell line and its relationship with hypoxia-inducible factor 1alpha(HIF-1alpha).

Methods: DEC1 and HIF-1alpha protein levels were detected in lung adenocarcinoma tissues by immunohistochemistry. A549 cells were cultured at hypoxia. MTT assay was used to determine the effect of cell viability. The apoptotic analysis was determined by flow cytometry. RT-PCR and immunocytochemistry were carried out to observe the DEC1 and HIF-1alpha mRNA and protein expression. HIF-1alpha mRNA and protein levels were detected in the stably transfected pcDNA-DEC1+/- A549 cells by RT-PCR and Western blotting. DEC1 mRNA and protein levels were detected in the stably transfected pcDNA-DEC1+/- A549 cells with or without HIF-1alpha antisense oligonucleotide treatment by RT-PCR and Western blotting.

Results: DEC1 was specifically located in 40 (48.8%) lung adenocarcinoma tissues. The results of the MTT test showed the growth of the stably transfected pcDNA-DEC+ A549 cells was higher than those of A549 cells and the stably transfected pcDNA-DEC- A549 cells. Hypoxia also induced the apoptosis of A549 cells and the stably transfected pcDNA-DEC+/- A549 cells. Hypoxia increased the mRNA and protein levels of DEC1 and HIF-1alpha. Both HIF-1alpha mRNA and protein levels decreased in the stably transfected pcDNA-DEC+ cells, but HIF-1alpha antisense oligonucleotide had no effect on DEC1 in the stably transfected pcDNA-DEC+/- A549 cells.

Conclusions: DEC1 is a marker of tumor hypoxia. DEC1 downregulates the HIF-1alpha at both mRNA and protein levels at hypoxia in lung adenocarcinoma A549 cells.