Effect of arsenic trioxide and mechanism on growth of a heterologous graft model for human breast cancer in nude mice

Objective To study the inhibitory effect of arsenic trioxide ( As203 ) on the tumor growth of breast cancer line MDA - MB - 435s implanted subcutaneously in nude mice and its mechanism. Methods BALB/C -nu/nu nude mice were subcutaneously injected with MDA -MB -435s breast cancer cells that were ER - negative, and treated with intraperitoneal injection of As203 and DDP indifferent concentrations. The implanted tumor was weighed, and tumor inhibition rates were calculated.The expression of PTEN and Caspase - 7 induced by As203 were examined by immunohistochemical method. Results The growth of implanted tumor was markedly inhibited with DDP, low dose and high dose As203, and the inhibitory rates were 48.68%, 32.80% ,66.67% respectively. The immunohistochemical staining showed that the number of PTEN and Caspase -7 protein increased markedly ( P ＜0.05). Conclusions As203 inhabits the growth of human breast cancer cell implanted tumor. The molecular mechanism of As203 on induction of apoptosis of breast cancer ceils may be through increasing the expression of PTEN and Caspase - 7 ( P＜0.05 ). Key words: Breast cancer; Arsenic trioxide; Nude mice; PTE; Caspase-7