CO-029 is overexpressed in gastric cancer and mediates the effects of EGF on gastric cancer cell proliferation and invasion.

Tetraspanins are cell-surface glycoproteins and have received attention recently as both suppressors and promoters of metastasis. CO-029 is a member of the tetraspanin family and is implicated to be a metastasis-promoting tetraspanin in some cancers. However, the role of CO-029 in gastric cancer remains unexplored. The present study aimed to investigate the expression of CO-029 in gastric cancer tissues and to determine whether CO-029 is involved in the effects of epidermal growth factor (EGF) on gastric cancer cell proliferation and invasion. We collected clinical samples and found that the expression of CO-029 was increased both at the mRNA level and protein level in gastric cancer tissues in comparison to normal and tumor-adjacent tissues, as demonstrated by RT-qPCR and western blot analysis, respectively. Furthermore, we performed an in vitro experiment using AGS cells and observed that EGF promoted AGS cell proliferation and enhanced the invasion ability of the AGS cells, as shown by MTT assay and cell invasion assay, respectively. To the best of our knowledge, our results reveal for the first time, that CO-029 expression was affected by EGF in a concentration- time-dependent manner. The knockdown of CO-029 attenuated the effects of EGF on gastric cancer cell proliferation and invasion. These findings suggest that CO-029 is an oncogene in human gastric cancer and that CO-029 at least partially mediates the effects of EGF on gastric cancer cell proliferation and invasion. Our data may provide a novel target for therapeutic intervention in human gastric cancer.