Angiogenesis is involved in the malignant transformation of cancers. Vascular endothelial growth factor (VEGF) is important in inducing angiogenesis. Cultured cells play an important role in analyzing the regulation of VEGF expression, and it is revealed that VEGF expression is induced under hypoxia. However, it has been shown that there are differences in the pathway for gene expression between two-dimensional (2D) cells and in vivo cells. Three-dimensional (3D) spheroids constructed in 3D culture with a gene expression pattern more similar to that of in vivo cells than 2D cells have been used to solve this problem. This study analyzed the VEGF gene expression pathway in 3D spheroids of human lung cancer cells, A549 and H1703. Hypoxia-inducible factor-1α (HIF-1α) and aryl hydrocarbon receptor nuclear translocator (ARNT) regulated VEGF gene expression in 3D spheroids. However, VEGF gene expression was not regulated by HIF-1α in 2D cells. To conclude, we found that the regulatory pathway of VEGF gene expression is different between 2D cells and 3D spheroids in human lung cancer cells. These results suggest the possibility of a new VEGF gene expression regulation pathway in vivo. In addition, they show useful knowledge for the analysis of angiogenesis induction mechanisms and also demonstrate the usefulness of 3D spheroids.
Keywords: aryl hydrocarbon receptor nuclear translocator; hypoxia-inducible factor-1α; lung cancer; three-dimensional spheroid; vascular endothelial growth factor.