Abstract: Objective To investigate the effect of interference of CTPS gene on toosendanin-induced apoptosis of gastric cancer MKN-45 cells. Methods Bioinformatic analysis was used to analyze CTPS gene expression in human gastric cancer tissues and the overall survival of gastric cancer patients with high CTPS gene expression. Human gastric cancer MKN-45 cells were transfected with a short hairpin interfering RNA targeting CTPS gene, and 48 h later, qRT-PCR and Western blotting were used to detect cellular expression CTPS at both the mRNA and protein levels. MKN-45 cells with CTPS knockdown were treated with 80 nmol/L toosendanin for 48 h, and the cell viability was assessed with MTT assay; the cell morphology was observed using laser confocal microscope, and the expression of γH2AX was detected with immunofluorescence assay. Results Bioinformatic analysis suggested that CTPS was highly expressed in human gastric cancer tissues, and gastric cancer patients with high CTPS gene expression had a shorter overall survival. MKN-45 cells transfected with Sh-CTPS interference vector showed significantly lowered cell survival rate (P<0.01) with obvious cell shrinkage, irregular morphology, typical apoptotic changes, and increased cell apoptosis rate (P<0.05). Treatment of the transfected cells with 80 nmol/L toosendanin for 48 h resulted in further reduction of the cell survival rate (P<0.001), and the cells showed an increased apoptotic rate (P<0.05) with appearance of apoptotic bodies. Conclusion Interference of CTPS gene can promote TSN-induced apoptosis of gastric cancer MKN-45 cells.

Key words: CTPS gene; toosendanin; gastric cancer; MKN-45 cells