Abstract:Objective To study the inhibitory effect of arsenic trioxide(As2O3) on the tumor growth of breast cancer cell line MCF7 implanted subcutaneously in nude mice and its mechanism.
Methods BALB/Cnu/nu nude mice were subcutaneously injected with MCF7 breast 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 of the implanted tumor was detected by flow cytometry. The expressions of bcl2 and Fas induced by As2O3 were examined by immunohistochemical method. Routine blood test and bone marrow test were used to observe the function of hematopoietic system after As2O3 treatment.
Results The growth of implanted tumor was markedly inhibited with 5FU, low dose and high dose As2O3, the inhibitory rates being 38.33%、51.42% and 62.43%,respectively. The inhibitory effect of As2O3 was significantly stronger than that of 5FU(P<0.01). The apoptosis rate of MCF7 cells treated with the 2 concentrations of As2O2 was significantly higher than that of 5FU treated group. Breast cancer cells in all the study groups showed G2/M stage arrest, while a marked apoptosis peak was observed before the G1 peak. The immunohistochemical staining showed that the number of bcl2 protein positive cells decreased, and the number of Fas protein positive cells increased. The function