Ajuba dysregulation has been reported in several human
cancers. However, its expression patterns and biological roles in human
gastric cancers have not yet been characterized. In the current study, we found that Ajuba
protein was increased in
gastric cancer tissues and in cell lines. High Ajuba expression positively correlated with the
tumor-node-
metastasis (TNM) stage,
lymph node metastasis and poor prognosis. The
Cancer Genome Atlas (TCGA) and Oncomine microarray data mining also suggested that Ajuba
mRNA upregulation in
gastric cancer tissues. We used SGC-7901 and NCI-N87 cell lines for Ajuba overexpression and
siRNA knockdown respectively. MTT and colony formation assays indicated that Ajuba overexpression increased proliferation rate and colony formation ability while Ajuba
siRNA inhibited proliferation rate and colony formation ability. AnnexinV and JC1 staining showed that Ajuba downregulated
cisplatin induced apoptosis while it upregulated mitochondrial membrane potential. Ajuba overexpression also inhibited
caspase-3 and PARP cleavage, while Ajuba depletion showed the opposite effects. Notably, Ajuba enhanced
glucose metabolism by upregulating
glucose uptake,
glucose consumption,
lactate production and
ATP production. We further revealed that Ajuba positively regulated
cyclin D1, Bcl-xL and GLUT1 at both
mRNA and
protein levels. Analysis of TCGA dataset revealed that there were positive correlations between Ajuba and
cyclin D1, Bcl-xL, GLUT1 at the
mRNA levels. Further investigation demonstrated that Ajuba overexpression inhibited Hippo signaling by upregulating YAP
protein expression. Depletion of YAP by
siRNA abolished the effect of Ajuba on
cyclin D1, Bcl-xL and GLUT1. Together, our study showed that Ajuba was overexpressed in human
gastric cancers, where it increased cell growth and chemoresistance. Our data also identified novel roles of Ajuba in
gastric cancer progression involving regulating
glucose uptake and mitochondrial function through the YAP-GLUT1/Bcl-xL axis, making it a potential therapeutic target.