TPX2 siRNA regulates growth and invasion of esophageal cancer cells.

PURPOSE: Observe how specific small RNA interference (siRNA) aimed at TPX2 gene suppresses TPX2 gene expression in esophageal cancer EC9706 cells and the effect on esophageal cancer cell growth and invasion ability.

METHODS: Transfect TPX2 siRNA into EC9706 cells via lipofectamin 2000. The experiments were divided into three groups, a negative control, a blank control and an siRNA interference group (24h, 48h, 72h, 96h). We examined RNA and protein level alteration of the TPX2 gene after TPX2 siRNA transfection by RT-PCR and Western blot analysis. Detection of how TPX2 siRNA influences EC9706 cell proliferation was done by MTT, cell apoptosis monitored through Tunel assay, in vitro invasion ability via Boyden chamber and cell cycle change by flow cytometry.

RESULTS: After effective siRNA transfection, TPX2 mRNA and protein expression level in siRNA interference group were (0.31±0.08, 0.39±0.12),72h after transfection, significantly lower than blank control group (1.00±0.01) and negative control group (0.98±0.11), (F=71.182, t1=8.17, t2=7.90, P<0.05); MTT results demonstrated that cell growth and proliferation were inhibited and the inhibition rate was up to 35.4% (P<0.05) compared with the control group. TUNEL results indicated that cell apoptosis index in siRNA interference group was 18.28±0.35, higher than that in blank control group (4.07±0.26)and negative control group (4.13±0.22), (F=244.5, t1=60.61, t2=53.32, P<0.01). Boyden chamber results showed that the transmembrane cell number was 45.30±8.08 in siRNA interference group, less than blank control group (121.90±7.83), (F=122.46, t1=11.81, t2=10.47, P<0.01); besides, in siRNA interference group cell invasion inhibition rate was 71.42±9.12, higher than negative control group (5.65±3.55), (t=14.256, P<0.01). Flow cytometry results illustrated that more EC9706 cells went into apoptosis and cell cycle arrested in S phase. Similar results were obtained by in vivo transplantation, as TPX2 siRNA transfection significantly reduced tumor growth of the xenograft in nude mice.

CONCLUSION: siRNA could effectively inhibit the invasion and metastasis of EC9706 cells, promote the apoptosis of tumor cells and may become a new approach for treatment of esophageal carcinoma.