Effect of human trophoblast cell-surface antigen 2 gene expression by RNA interference on proliferation and apoptosis of tongue squamous cell carcinoma and its mechanism

Abstract

Objective: To investigate the effect and its mechanism of human trophoblast cell-surface antigen 2 (Trop2) gene expression was inhibited in squamous cell carcinoma of tongue on the proliferation and apoptosis of cancer cells. Methods: A total of 46 patients from February 2014 to May 2016 received radical treatment of tongue cancer from oral and maxillofacial surgery of the First Affiliated Hospital of Zhengzhou University were enrolled in this study. Real time PCR and Western blotting were used to detect mRNA and protein expression of Trop2 in tongue squamous cell carcinoma and corresponding adjacent tissues; NC-siRNA and Trop2-siRNA were transfected into human tongue squamous cell carcinoma CAL-27 cells, a blank control group (control) was set, the expression of Trop2, Ki-67, cyclin D1, cleaved caspase3, Notch1, Hes1 protein after transfected for 48 h were detected by Western bloting; cell proliferation was detected by cell counting kit-8; cell cycle and apoptosis rate were detected by flow cytometry. Results: The mRNA (5.72±1.13) and protein expression (0.77±0.06) of Trop2 gene in tongue squamous cell carcinoma were significantly higher than those in adjacent tissues (0.92±0.15, 0.11±0.01, P<0.05); Trop2 protein expression after transfeced Trop2-siRNA (0.08±0.01) in CAL-27 cells decreased significantly (0.46±0.05); the survival rate (64.28±4.12)%, S cells (14.54±1.02)% and Ki-67 (0.12±0.01), cyclin D1 (0.04±0.01) protein expression in Trop2-siRNA group were significantly lower than those in control group [(100.00±1.02)%, (27.33±1.11)%, (0.24±0.02), (0.20±0.02)] and NC-siRNA group [(96.55±2.43)%, (26.67±1.23)%, (0.26±0.03), (0.21±0.024)], the apoptosis rate (23.55±1.45)%, G0/G1 cells (72.32±0.94)% and the expression of cleaved caspase 3 (0.16±0.02), Notch1 (0.62±0.06) and Hes1 (0.50±0.05) protein were significantly higher than control group and NC-siRNA group (P<0.05). Conclusions: The expression of Trop2 gene was inhibited in tongue squamous carcinoma cells can reduce the proliferation of cancer cells, block the cells in phase G1, and promote the apoptosis of cells. The mechanism is related to the up regulation of Notch1 signaling pathway.