PBX3 is overexpressed in gastric cancer and regulates cell proliferation

The pre-leukemia transcription factor 3 (PBX3) is a member of the PBX family of transcription factors, which is known to increase DNA-binding/transcriptional activity of HOX proteins and regulate genes involved in development. Recently, PBX3 was reported to be involved in a variety of cancers, while its implication in gastric cancer is unclear. This study aimed to investigate its clinical significance and biological function in gastric cancer. PBX3 expression was analyzed in 90 gastric cancer specimens using immunohistochemistry. PBX3 was overexpressed in 30 cases (33.33 %). Importantly, PBX3 overexpression positively correlated with advanced invasion depth (p = 0.0017), Clinical stage (p = 0.0127) and grade of tumor differentiation (p = 0.0158). PBX3 was also overexpressed in gastric cancer cell lines. Plasmid transfection was performed in AGS and SGC-7901 gastric cancer cell line with low endogenous PBX3 expression. MTT and colony formation assay were carried out to assess the role of PBX3 in proliferation. PBX3 overexpression in gastric cancer cell lines accelerated cell proliferation rate and colony formation ability, with upregulation of PCNA expression. In addition, matrigel invasion assay showed that PBX3 transfection also increased cell-invading ability. These results validate the role of PBX3 as a clinically relevant oncoprotein and establish PBX3 as a promising therapeutic target of gastric cancer.