Expression of cell adhesion molecule 4 in gastric cancer tissues and its effect on apoptosis, autophagy, invasion and metastasis of human gastric cancer cell line BGC823

Abstract

Objective To investigate the expression of cell adhesion molecule 4 (CADM4) in gastric cancer tissues and cell lines as well as its effect on apoptosis, autophagy, invasion and metastasis of human gastric cancer cells BGC-823. Methods The expression of CADM4 in 60 cases of gastric cancer tissues and their adjacent tissues was detected by Real-time polymerase chain reaction (PCR). The relationship between CADM4 expression and clinicopathological features of gastric carcinoma was analyzed. The expression of CADM4 was detected in 7 strains of gastric cancer cells (HGC-27, BGC-823, MKN-45, MGC-803, SGC-7901, NCL-N87 and AGS) and the normal gastric mucosa cell line, GES-1, was used as the control. The gastric cancer cells with the lowest level of CADM4 were chosen for the transfection with lentivirus vector of overexpressing CADM4 (LV-CADM4). Real-time PCR was used to detect the expression of CADM4 mRNA in the transfected BGC-823 cells. Flow cytometry was used to detect the cell apoptosis ratio and mitochondrial trans-membrane potential. Transwell invasion assay and cell scratch assay were used to detect the migration and invasion of transfected BGC-823 cells. Western blotting was used to detect the expression of proteins associated with apoptosis, autophagy, invasion and metastasis. Results The relative expression of CADM4 in gastric carcinoma tissues was 0.29±0.03, lower than that (1.20±0.15) of the adjacent tissues (P=0.000). Its expression was related to TNM clinical stage, differentiation, depth of invasion and lymph node metastasis (all P=0.000). The expression level of CADM4 in BGC-823 cells was obviously lower than that in HGC-27, MKN-45, MGC-803, SGC-7901, NCL-N87, AGS and GES-1 cells (P=0.000). As compared with blank control group and negative virus control group, LV-CADM4 promoted the apoptosis of BGC-823 cells and greatly decreased the mitochondrial trans-membrane potential (all P=0.000); meanwhile the expression levels of B cell lymphoma/leukemia-2 (bcl-2), p62 and matrix metalloproteinase (MMP)-9 proteins were down-regulated, and the expression levels of bcl-2 associated X protein (bax), Caspase-9, microtubule-associated protein 1 light chain 3 (LC3) and Beclin1 proteins were up-regulated (all P=0.000). Conclusion The expression of CADM4 was down-regulated in gastric cancer tissues and cells, and up-regulation of CADM4 can induce apoptosis and autophagy via the mitochondrial pathway in BGC-823 cells, and inhibit the invasion and metastasis in BGC-823 cells. Key words: Gastric cancer; Apoptosis; Autophagy; Invasion; Metastasis