Positive correlation between HOTAIR and HER2 expression and the relevance to miR-331-3p/miR-124 expression levels. (A) Bivariate correlation analysis of the relationship between HOTAIR expression and miR-331-3p, or miR-124 level. (B) BGC-823 cells were transfected with plasmids encoding miR-331-3p or miR-124, and qRT-PCR was used to detect the miRNA levels compared with controls (miR-NC). (C) MTT assay and colony-forming growth assay were performed to determine the proliferation of miR-331-3p or miR-124 transfected BGC-823 cells. (D) Left: immunostaining of HER2 protein in advanced gastric cancer tissue samples. Upper: immunostaining of HER2 was negative in gastric cancer tissues with relatively low HOTAIR expression. Lower: immunostaining of HER2 was positive in gastric cancer tissues with relatively high HOTAIR expression. Right: bivariate correlation analysis of the relationship between HOTAIR and HER2 expression level. *P < 0.05, **P < 0.01.