Human health and public safety are being threatened while chemicals bring convenience and comfortable to our life. How to reduce and avoid the hazard of chemicals via toxicity warning is becoming more and more important. Today it is necessary to estimate new chemicals conveniently, quickly and precisely. The warning model of chemicals in toxicology has a favorable prospect of application. The toxic effect and kinds of models of chemicals and the study of quantitative structure activity relationships (QSAR) in toxicity research were reviewed in this paper.

Objective To investigate the effects of salinomycin on the cell proliferation and epithelial-mesenchymal transition (EMT) of MCF-7 mammosphere (MCF-7 MS). Methods Breast cancer MCF-7 cells were cultured in suspension in serum-free medium to obtain MCF-7 MS. The cell viability of MCF-7 MS cells treated with serial concentrations of 0, 10, 30, 100, 300, 1 000, 3 000 and 10 000 nmol/L of salinomycin for 24 hours were detected by CCK-8 assay. The half maximal inhibitory concentration (IC50) was calculated. Western blot analysis was performed to detect the expression levels of E-cadherin and Snail in MCF-7 MS cells treated with 30 nmol/L and 60 nmol/L salinomycin. The same capacity of DMSO was added to MCF-7 MS as control group. The xenograft tumors from MCF-7 MS transplant mice were divided into control group (the same capacity of normal saline) and salinomycin group (5 mg/kg salinomycin), then the expressions of E-cadherin and Snail were dectected by immunohistochemical staining. Results With the increased concentration of salinomycin, the cell survival rate of MCF-7 MS cells decreased (P<0.05). The IC50 after 24 h-treatment was 989 nmol/L. Both 30 and 60 nmol/L of salinomycin increased the expression of E-cadherin and decreased the expression of Snail compared with control group. In addition, 60 nmol/L treatment group showed more significant effect (P<0.05). In xenograft tumors from MCF-7 MS transplant mice, the expression of Snail decreased, and E-cadherin increased in salinomycin treatment group compared with control group (P<0.01). Conclusion Salinomycin can inhibit the cell proliferation and EMT in MCF-7 MS cells, which is a potential drug to target cancer stem cells.