Arsenic trioxide inhibits the growth of human colon cancer cell subcutaneous implanted tumor and its mechanism

Objective To study the inhibitory effect of arsenic trioxide(As 2O 3) on the growth of SW480 cell subcutaneous implanted tumor in nude mice and its mechanism.Methods BALB/C-nu/nu nude mice were subcutaneously injected with SW480 colon cancer cell line,and treated with intraperitoneal injection of As 2O 3 and 5-FU in different concentrations.The implanted tumor was weighed,and the tumor inhibition rates were calculated .The apoptosis rates of SW480 cells were assessed by TUNEL method. The expressions of bcl-2 and Fas induced by As 2O 3 were examined by immunohistochemistry.Results The tumor-bearing mice were treated with 5-FU, low dose and high dose As 2O 3 .The growth of implanted tumor was markedly inhibited ,the inhibitory rates being 41.51% ,53.21% and 58.02%,separately.The inhibitory effect of As 2O 3 was significantly stronger than that of 5-FU(P0.01).The apoptosis rates of SW480 induced by As 2O 3 were significantly higher than those of 5-FU (P0.01) .The immunohistochemical staining showed that the number of bcl-2 protein positive cells decreased and the number of Fas protein positive cells increased.Conclusion As 2O 3 inhibits the growth of human colon cancer cell implanted tumor and induces apoptosis of SW480.The molecular mechanism of As 2O 3 on induction of apoptosis of colon cancer cells may be decrease of the expressions of bcl-2 and increase of the expressions of Fas.