Role of a novel EGF-like domain-containing gene NGX6 in cell adhesion modulation in nasopharyngeal carcinoma cells

The epidermal growth factor (EGF)-like domain is involved in receptor-ligand interactions, extracellular matrix formation, cell adhesion and chemotaxis. Nasopharyngeal carcinoma associated gene 6 (NGX6) is a novel EGF-like domain-containing gene located at the high frequent loss of heterozygosity (LOH) region 9p21-22 associated with nasopharyngeal carcinoma (NPC). It is down-regulated in NPC and its over-expression can delay the cell cycle G₀-G₁ progression in NPC cells. In the present study, in situ hybridization analysis, using NPC tissue microarrays, showed that loss of NGX6 expression was associated with NPC lymph node metastasis. The Tet-on gene expression system and cDNA array techniques were used to profile the potential targets of NGX6. We found that NGX6 can influence the expression of some cell adhesion molecules in NPC cells. NGX6 can associate with ezrin, a linkage between the cell membrane and cytoskeleton. The NGX6 protein was expressed on the cell surface as a glycoprotein. Ectopic induction of NGX6 can impair NPC cell migration and invasive ability as well as improve cell adhesion and gap junctional intercellular communication, and can suppress tumor formation in vivo. The data revealed that NGX6 plays a role in cell adhesion modulation in NPC cells.