Abstract: Objective: To observe the effect of TrKA to the growth of breast cancer cells,investigate the molecular mechanism and provide new target of medicine for the treatment of breast cancer.Methods: The expression of TrKA mRNA and protein was detected by Real Time-PCR and Western-blot before and after interference.The proliferated effect of nerve growth factorl(NGF) was tested by MTT and the protein expression of caspase-3 was detected by Western-blot after RNAi.Results: The levels of TrKA mRNA and protein were decreased by 74.7% and 80.5% respectively after RNAi(P< 0.01);NGF could stimulate the proliferation of MCF-7 cells.The OD₄₉₀ of the group of MCF-7+NGF was higher than that of the group of MCF-7 at each time point(P<0.01).The effect of NGF to the proliferation of cells was inhibited after RNAi.The absorption of the group TrKA-SiRNA and TrKA-SiRNA+NGF were lower than the group MCF-7 at each time(P<0.01);the protein of caspase-3 was activated in the group of TrKA-SiRNA and TrKA-SiRNA+NGF compared with MCF-7.The protein expression of cleaved caspase-3 was increased(P<0.01).Conclusions: Transfection of TrKA gene SiRNA can inhibit cellular proliferation and promote apoptosis.This suggests that the biologic axis of NGF-TrKA plays a siginificant role in the growth of breast cancer and the axis of interference may be a new target for the breast cancer treatment.