LncRNA CASC9 Suppressed the Apoptosis of Gastric Cancer Cells through Regulating BMI1

Long noncoding RNAs (lncRNAs) play important roles in regulating the apoptosis of gastric cancer (GC) cells. This study aims to investigate the underlying mechanism of lncRNA CASC9 in regulating the apoptosis of GC cells. The expressions of lncRNA and protein in GC tissues and cell lines were detected by qRT-PCR and western blot. GC cell apoptosis was detected by flow cytometry analysis. RNA pull-down and RNA immunoprecipitation (RIP) assays were conducted to verify the interaction between CASC9 and BMI1. LncRNA CASC9 was upregulated in GC tissue and GC cells, and high CASC9 expression was positively correlated with TNM stage and lymph node metastasis. Silencing CASC9 promoted the apoptosis of GC cells. LncRNA CASC9 could interact with BMI1 and positively regulate BMI1 expression. Silencing CASC9 promoted the ubiquitination of BMI1. In addition, lncRNA CASC9 regulated the apoptosis of GC cells through BMI1. Furthermore, interfering CASC9 inhibited the tumor growth of GC. LncRNA CASC9 could interact with BMI1 to regulate the degradation of BMI1, thus to affect the apoptosis of GC cells and suppressed tumor growth.