Preparing PAMAM-NK4 nano complexes and examining their in vitro growth suppression effects in breast cancer

Background: This study sought to examine the suppression of the NK4 (which is a fragment that originates from the trypsin digestion of the hepatocyte growth factor) gene as mediated by new nano material polyamidoamine (PAMAM) dendrimers in the growth of breast cancer cells MDAMB-231 and MCF-7, and the therapeutic effects in a nude mice model of transplanted tumor cell MDA-MB-231. Methods: We built PAMAM-NK4 nano particles and detected the in vitro transfection rate. Nano complexes and blank plasmid PAMAM dendrimers were transfected to MDA-MB-231 and MCF-7 cells, respectively. The western-blotting method, MTT experiment method, and bead method were used to detect the effects of the nano complexes on NK4 protein expression, cell proliferation, and cell apoptosis. The nude mice model of transplanted tumor cell MDA-MB-231 comprised 40 nude female mice who were subject to injections. The mice were randomly divided into four groups, comprising 10 mice per group. The control, blank plasmid and treatment groups were subcutaneously injected with 0.2 mL of 0.9% NaCl (Sodium chloride) solution, 0.2 mL of plasmid solution (including 100 mu g PAMAM pcDNA3.1(-) blank plasmid nano complexes) and 0.2 mL of plasmid solution (including PAMAM-NK4 100 mu g) beside the tumor inoculation spot, respectively. The positive control group was intraperitoneally injected with 0.2 mL of doxorubicin solution, including 100 mu g doxorubicin. Western blotting was used to detect the NK4 protein expression of the transplanted tumor tissues of the various groups. Results: NK4 protein was successfully expressed in MDA-MB-231 and MCF-7 cells transfected with PAMAM-NK4 nano particles, and cell proliferation was suppressed and cell apoptosis was induced. The tumor volumes and masses of the treatment and positive control groups were obviously smaller than those of the control group. The differences were statistically significant (P