Knockdown of long noncoding RNA CCAT1 inhibits cell growth, invasion and peritoneal metastasis via downregulation of Bmi-1 in gastric cancer

Abstract

Long noncoding RNA colon cancer-associated transcript 1 (lncRNA CCAT1) is highly expressed in gastric cancer (GC) tissues compared to normal counterparts and CCAT1 up-regulation promotes proliferation and migration of GC cells in vitro. B-cell specific moloney leukemia virus insertion site 1 (Bmi-1) expression positively correlates with tumor progression. This study investigates the biological functions of CCAT1 and the relationships between CCAT1 and Bmi-1 in GC progression. Herein, CCAT1 was knocked down by specific shRNA transfection in two human GC cell lines (MGC-803 and SGC-7901) and the effects of this knockdown on GC cell proliferation, cell cycle migration and invasion were investigated in vitro. The effect of CCAT1 knockdown on peritoneal metastasis was assessed in nude mice, and Bmi-1 expression levels were examined both in vitro and in vivo. The results showed that Bmi-1 down-regulation and CCAT1 knockdown markedly inhibit cell proliferation, migration and invasion, arrests the cell cycle in the G0/G1 phase in vitro and inhibit peritoneal metastasis in nude mice. The combined results establish that CCAT1 is functionally involved in growth and metastasis of GC cells and it is therefore a potential target for GC therapy.