HAX-1 overexpression in gastric cancer promotes cell proliferation

BACKGROUND: HAX-1 is involved in the regulation of cellular processes such as apoptosis, proliferation and migration and is closely related to tumorigenesis and tumor metastasis. However, expression of HAX-1 in gastric cancer and its role in tumor development and progression remain unclear. METHODS: Quantitative polymerase chain reaction was used to detect the expression of HAX-1 mRNA in gastric cancer tissues and adjacent non-tumorous tissues. Expression of HAX-1, caspase-3 and caspase-9 was detected by immunohistochemistry in gastric cancer. Small hairpin RNA (shRNA) plasmid was employed to establish SGC-7901 cell lines that expressed HAX-1 at low levels. The effect of HAX-1 expression on cell proliferation will be studied at the cell level. RESULTS: Quantitative polymerase chain reaction (qPCR) showed HAX-1 mRNA expression to be significantly upregulated in gastric cancer tissues. Based on immunohistochemical analysis, upregulation of HAX-1 protein expression correlates positively with the degree of tumor differentiation, vascular tumor thrombus, tumor-node-metastasis stage and lymph node metastatic status and negatively with expression of the apoptosis-related proteins caspase-3 and caspase-9. In addition, high HAX-1 protein expression indicates a poor prognosis. Serum starvation-release experiments revealed that HAX-1 promotes the proliferation of SGC-7901 gastric cancer cells; as cell proliferation increased, expression of HAX-1 also increased, whereas the expression levels of the apoptosis-related proteins caspase-3 and caspase-9 decreased. HAX-1 siRNA transfection experiments demonstrated that HAX-1 gene knockdown causes cell cycle arrest at the G0/G1 phase, inhibits proliferation, and downregulates HAX-1 expression while enhancing expression of apoptosis-related proteins. CONCLUSIONS: HAX-1 might exert its proliferation-promoting and anti-apoptotic effects by inhibiting expression of the apoptosis-related proteins caspase-3 and caspase-9.HAX-1 may be a potential target for the treatment of gastric cancer.