OBJECTIVETo investigate the suppressive effect and mechanism of action of Zilongjin (ZLJ, a composite Chinese drug) on the growth of human breast carcinoma cell line MCF-7 in vivo and in vivo.

METHODSThe cell survival rate and clone forming efficiency were observed by direct cell counting with trypan blue staining and double layers soft agar test; the p-ERK 1/2 expression was analyzed using Western blotting; 17-beta-estrogen pellet embedding was adopted to make the subcutaneous transplanted tumor MCF-7 cell in BALB/c nude mice for detecting the tumor growth suppressive effect of ZLJ (20 g crude drug/kg).

RESULTSThe survival rate of MCF-7 cell was obviously decreased by ZLJ in a time and dose-dependent manner; only few and small clones on soft agar could be found after treated with ZLJ, the inhibition rates of clone formation(%) for 0.75, 1.5, 3, 6 mg/mL of ZLJ were 12.66 +/- 1.54, 88.83 +/- 2.13, 100 and 100, respectively, as compared with that of non-treated. The expression of p-ERK 1/2 was suppressed and the ability of the tumorigenicity in nude mice was reduced effectively by ZLJ. The mean volumes and weights of tumor in the test group and the control group were (0.73 +/- 0.58) cm3 vs (1.36 +/- 0.64) cm3 and (1.02 +/- 0.25) g vs (1.66 +/- 0.09) g respectively, showing significant difference (P<0.05), and the tumor inhibition rate of ZLJ was 38.55%.

CONCLUSIONZLJ shows obviously suppressive actions on malignant proliferation, transformation and tumorigenicity of human breast carcinoma cell line MCF-7; the down-regulation of p-ERK 1/2 protein may involve in these effects.