Figure 6
Effect of recombinant pigment epithelium-derived factor (rPEDF) on the growth of endocrine-sensitive MCF-7 and endocrine-resistant MCF-7:5C breast cancer cells in vitro and in vivo. (a) MCF-7 and MCF-7:5C cells were treated with increasing concentrations of rPEDF, rPEDF + anti-PEDF antibody (anti-PEDF), or anti-PEDF antibody for 7 days, and cell proliferation was determined using a DNA quantitation kit as described in Materials and methods. Experiments were repeated three times, and data are shown as mean ± standard deviation (SD). *P < 0.001 compared with untreated controls. (b) MCF-7:5C cells were treated with rPEDF, anti-rPEDF, or rPEDF + anti-rPEDF for 72 hours and apoptosis was determined by TUNEL staining. Bar graph: summary of percentage of apoptotic cells counted in five fields from three experiments. Data presented as mean ± SD. (c) Effect of rPEDF on the growth of MCF-7:5C cells in vivo. MCF-7:5C cells were bilaterally injected into the mammary fat pad of ovariectomized nude mice, and when tumors reached an area of 0.1 cm2 the mice (n = 15/group) were randomized into two treatment groups: PBS or rPEDF. The mean cross-sectional tumor area was measured up to 30 days. Bar graph: mean cross-sectional tumor area in the control group and the PEDF-treated group. (d) Intratumoral microvessel density (MVD) in tumor tissues was determined by immunohistochemical staining by an endothelial-specific antibody CD34; PBS group (×200) and PEDF group (×200). Quantitative analysis of microvessel density is also shown. Data presented as mean ± SD.