Effect Of Rhodiola On Human Breast Cancer And Its Mechanism

Rhodiola can result in increase of new blood vessels and improve myocardial ischemia through inducing expression of angiogenetic factors such as VEGF, bFGF and FactorⅧ. On the other hand, Rhodiola can inhibit the proliferation of some kinds of cancer cells such as leukemia HL-60 cell and liver cancer cell. However there is no report on the effect of Rhodiola on human breast cancer and its angiogenesis.For the first time, this study explored the influence of Rhodiola on human breast cancer cells and human breast caner Xenografts in nude mice including proliferation, differentiation and angiogenesis, and speculated its molecular mechanisms.The study included two parts as follow.Part One Effect of Rhodiola on Human Breast Cancer Cell Line MDA-MB-435 and its MechanismObjective To investigate the influence of Rhodiola on proliferation of human breast cancer cell line MDA-MB-435 and expression of angiogenetic factors.Methods Human breast cancer cells MDA-MB-435 were treated with different concentration of Rhodiola extract. The WST (water-soluble tetrazolium salt) methods were used to analyze the cells proliferation. The mRNA expression of VEGF (vascular endothelial growth factor) and DARC (Duffy antigen receptor) in the treated MDA-MB-435 cells were detected by RT-PCR. Flow cytometry was used to examine the change of distribution of stages of the treated cells.Result (1) After treated by Rhodiola extract for 24hours, the morphological feature of MDA-MB-435 cells had changed signifi-cantly with the increase of drug concentration. (2)Rhodiola treatment groups showed S-stage arrest and the blocking was more significant with higher drug concentration. (3) Rhodiola extract clearly inhibited proliferation of human breast cancer cell line, MDA-MB-435, and inhibition was more significant with time and the dose increase. (4) After Rhodiola extract intervention given to human breast cancer cell MDA-MB-435 for 24h, there was not difference of VEGF expression among all groups; after 44h treatment, the VEGF mRNA levels were down-regulated in Rhodiola group, and there was obviously different between Rhodiola groups and control group. (5) After 24h Rhodiola extract treatment, expression of DARCmRNA were increased significantly, and the elevated degree by different drug dose was similar.Part Two Effect of Rhodiola on Human Breast Cancer Xenografts and its MechanismObjective To study the effect of Rhodiola on human breast cancer Xenografts and explore its mechanism.Methods Female BALB/c nude mice were implanted with human breast cancer MDA-MB-435 cells into nipple, and randomized into two groups: Rhodiola group and NS group. The treatment period was 4 Weeks. Comparing tumor volumes of two groups. It was detected by immunohistochemistry staining that the proliferation of cancer cells in human breast cancer Xenografts, the expression of proteolytic enzymes related to tumor metastasis and cellular level of angiogenetic factors, and microvascular density in human breast cancer Xenografts.Result (1) The mean tumor volume of Rhodiola group was99. 95mm3, less than NS control group (174.60mm~3) (P=0. 535) . (2), after Rhodiola was given to nude mice for 4 weeks, the proportion and intensity of cellular Ki-67 staining in Xenografts were decreased comparing with NS group, and average H-score was 86 ±34.4, lower than control group (152.8 ± 33.3) . Cellular PCNA staining in Xenografts of Rhodiola group was 210 ± 27.4, less than that of control group, but there was no statisticalsignificance (P=0.221) . (3) The level of Cathepsin in Xenografts in control group was higher than that of Rhodiola group(168 ±64.19 vs. 72 ± 50.70, P=0.03) , and expression of MMP2 between two groups was similar (176 + 65.80 vs. 90 + 29.15, P=0.04). (4) The proportion and intensity of VEGF staining in Xenografts of Rhodiola group was lower comparing with control group, and the difference in H-score between two groups (60 + 30.82 vs. 138 + 58.48) was statistically significant. Expression of DARC in Rhodiola group was up-regulated, and the difference in H-score between two groups(102 ± 31.14 vs. 60 ± 23.45) was also statistically significant. There were more newly formed vessels in NS control group than in Rhodiola-treatment group (48.13 ± 3.70/HP vs. 30.27 ± 7.71/HP, P=0.002).Conclusion In vitro and vivo studies, Rhodiola could inhibit the proliferation of human breast cancer MDA-MB-435 cells, reduce the expression of proteolytic enzymes and angiogenetic factors and microvascular density in human breast cancer Xenografts, and up-regulate the level of angiostatic factor DARC. It was not seen that Rhodiola accumulated tumor growth.