Effect of forkhead/winged helix transcripition factor 3 on apoptosis of colorectal cancer cells

Abstract

Objective To investigate the expression of forkhead/winged helix transcripition factor 3 (Foxp3) in colorectal cancer and the effect of Foxp3 short hairpin RNA (shRNA) on apoptosis of colorectal cancer cells. Methods Western blotting was used to detect the expression level of Foxp3 in colorectal cancer tissues and corresponding paracancerous tissues. The expression of Foxp3 in human colorectal cancer cells HCT116, SW480, RKO and human intestinal mucosal cell line CCC-HIE-2 was detected by Western blotting. Transfected Foxp3 shRNA1, Foxp3 shRNA2 and shRNA control to human colorectal cancer cells, which were named as Foxp3 shRNA1group, Foxp3 shRNA2 group, shRNA control group. At the same time, the non transfection group was established and transfection reagent was added into the non transfection group. After culturing 48 h, the expression level of Foxp3 in the cells was detected by Western blotting and reverse transcriptase-polymerase chain reaction (RT-PCR), and the higher interference efficiency of shRNA was screened. Flow cytometry was used to detect the apoptosis of cells. Results The expression levels of Foxp3 in the adjacent tissues and colon cancer tissues were: 0.24±0.05, 0.78±0.08, and the difference was statistically significant (P=0.000, t=63.254). The expression level of Foxp3 in human colorectal cancer cells HCT116, SW480, RKO was higher than that of CCC-HIE-2, and the expression level of Foxp3 was from low to high: RKO, HCT116, SW480. Later selection SW480 continue to study. The expression level of Foxp3 protein in the transfected group, shRNA control group, Foxp3 shRNA1 group and Foxp3 shRNA2 group were: 0.92±0.05, 0.93±0.07, 0.21±0.04, 0.34±0.06. The expression level of mRNA was as follows: 1.00±0.07, 1.01±0.08, 0.53±0.06, 0.79±0.08. Subsequent Foxp3 shRNA2 interference Foxp3 expression. The apoptosis rates of the non transfection group, shRNA control group and Foxp3 shRNA2 group were as follows: (13.21±3.12)%, (12.98±3.54)%, (42.01±6.72)%. The expression level of B cell lymphoma/lewkmia-2 (bcl-2) in Foxp3 group shRNA2 was 0.86±0.05, 0.85±0.06, 0.26±0.05. The expression level of cleaved cysteinyl aspartate specific proteinase 3 (Cleaved Caspase-3) was: 0.38±0.09, 0.39±0.08, 0.88±0.06. The expression level of p-signal transducers and activators of transcription 3 (STAT3) was as follows: 0.40±0.06, 0.39±0.04, 0.22±0.05. Conclusion Foxp3 was up-regulated in colorectal cancer tissues and cells. Interference of Foxp3 expression could promote apoptosis of human colorectal cancer cells. The mechanism may be related to STAT3 signaling pathway. Key words: Colorectal cancer; Apoptosis; Forkhead/winged helix transcripition factor 3; Signal transducers and activators of transcription 3 signaling pathway